At Sonnet, we've been developing 3D planar high frequency EM software since 1983, and our software has earned a solid reputation as the world's most

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1 14.52 Rev 1.0

2 At Sonnet, we've been developing 3D planar high frequency EM software since 1983, and our software has earned a solid reputation as the world's most accurate commercial planar EM analysis package for single and multi-layer planar circuits, packages and antennas. Sonnet Software Inc., founded by Dr. James C. Rautio, is a private company, entirely dedicated to the development of commercial EM software. We take great pride in providing quality technical support for our products with timely response--which we believe to be very important for high-end technical software products. Sonnet is based in Syracuse, NY, USA with representatives across the globe.

3 SONNET S KEYSIGHT ADS INTERFACE Published: November 2015 Release 16 Sonnet Software, Inc. 100 Elwood Davis Road North Syracuse, NY Phone: (315) Fax: (315) Copyright 1989,1991,1993, Sonnet Software, Inc. All Rights Reserved Registration numbers: TX , TX

4 Copyright Notice Reproduction of this document in whole or in part, without the prior express written authorization of Sonnet Software, Inc. is prohibited. Documentation and all authorized copies of documentation must remain solely in the possession of the customer at all times, and must remain at the software designated site. The customer shall not, under any circumstances, provide the documentation to any third party without prior written approval from Sonnet Software, Inc. This publication is subject to change at any time and without notice. Any suggestions for improvements in this publication or in the software it describes are welcome. Trademarks The program names, xgeom, emstatus, emvu, patvu, dxfgeo, ebridge, emgraph, gds, cvbridge, emserver, emclient, sonntcds, and sonntawr, Blink, Co-calibrated, Lite, LitePlus, Level2 Basic, Level2 Silver, and Level3 Gold are trademarks of Sonnet Software, Inc. Sonnet, em, and emcluster are registered trademarks of Sonnet Software, Inc. Windows XP, Windows Vista, Windows 7, Windows 8 and Internet Explorer are U.S. registered trademarks of Microsoft Corporation. AutoCAD and Drawing Interchange file (DXF) are trademarks of Auto Desk, Inc. Cadence and Virtuoso are trademarks of Cadence Design Systems, Inc. Agilent, ADS, and Touchstone are trademarks of Keysight Technologies. NI AWR and Microwave Office are registered trademarks and EM Socket is a trademark of National Instruments, Inc. HSPICE is a registered trademark of Synopsys, Inc. GDSII is a trademark of Calma Company. Flexera Software, Flexlm, FlexNet, InstallShield, are trademarks of Flexera Software, Inc. and/or InstallShield Co.Inc. in the United States of America and/or other countries. OSF/Motif is a trademark of the Open Software Foundation. X Window System is a trademark of The Open Group Linux is a registered trademark of Linus Torvalds. Red Hat is a registered trademark of Red Hat, Inc. SUSE, opensuse and SLES are registered trademarks of SUSE LLC. OpenGL is a registered trademark owned by Silicon Graphics, Inc. MATLAB is a registered trademark of The MathWorks, Inc. in the United States and/or other countries. Acrobat is a registered trademark of Adobe Systems Incorporated. Xpeedic and IRIS are registered trademarks of Xpeedic Technology. ODB++ is a registered trademark of Mentor Graphics Corporation. Modelithics is a registered trademark of Modelithics, Inc.

5 Table of Contents TABLE OF CONTENTS TABLE OF CONTENTS THE ANALYSIS BOX Coupling to the Box KEYSIGHT ADS INTERFACE TUTORIAL Introduction Installing the Keysight ADS Interface Copying the Examples Adding the Sonnet Design Kit to your Workspace Generating the Layout Importing Setup from the Schematic Substrate Analysis Box Ports Analysis Frequencies Subsectioning and Analysis Options Connectivity Checker Simulation Viewing Results in Sonnet Adding a Marker Viewing the Model Using the Model KEYSIGHT ADS INTERFACE System Requirements Licensing Changes in ADS Project Organization Projects versus Workspaces Installation for ADS Manual Installation Using Sonnet Manual Installation Using ADS Automatic Uninstall Manual Uninstall Using Sonnet

6 Agilent ADS Interface Manual Uninstall Using ADS Installation for ADS 2011 and Higher Manual Installation Using Sonnet Manual Installation Using ADS Adding the Sonnet Design Kit Automatic Uninstall Manual Uninstall Using Sonnet Manual Uninstall Using ADS Accessing Sonnet s Keysight ADS Interface Defining the Substrate Sonnet Materials Sonnet Dielectrics Mapping from ADS to Sonnet Viewing the Stackup Saving a Substrate File Using an Existing Sonnet Substrate Viewing the Stackup Defining the Box Sizes Top Metal, Bottom Metal Margins Displaying the Box Sonnet Custom Box Viewing the Box Estimating Sonnet Processing Time Ports Sonnet s Component Feature Options Simulation Program Subsectioning Adaptive Sweep Settings Project Options Translation Options (ADS to Sonnet) Model Options Create Dataset Analysis Frequencies

7 Table of Contents Adding/Editing Frequency Sweeps Editing a Frequency Type Deleting a Frequency Type Loading Frequency Sweeps Connectivity Checker States and Properties of the Interface Saving a State Loading a State Loading the Analysis Setup from the Schematic Loading the Analysis Setup from Momentum Summary of the Interface Running the Simulation Analysis Viewing the Subsectioning Estimating Box Resonances Cleaning Analysis Data Viewing the Results in Sonnet Sonnet s Response Viewer Current Density Viewer Far Field Viewer Auto Documentation Viewing the Results in ADS Creating a Dataset Deleting a Dataset Opening a New Data Display Opening an Existing Data Display Using the Models Creating an S-Parameter Model Deleting the Model Translating the Layout to a Sonnet Project Sonnet Features Not Available in ADS Using Sonnet s Project Editor Sonnet Task Bar Utilities in the Keysight ADS Interface Import Mdif File Open Translated Design

8 Agilent ADS Interface Default Settings for Sonnet States Preferences Analysis Box Preferences Substrate Preferences Frequencies Preferences Ports Preferences ABS Options Model Options Project Options Simulation Program Options Subsectioning Options Translation Options Other Preferences Keysight ADS License Check Unlocking Sonnet Keysight ADS Interface APPENDIX I VIA SIMPLIFICATION Introduction Via Array Simplification Via Array Criteria Additional Simplify Via Array Options Simplify Via Array Options Number of New Via Metals Created Simplified Via Array Loss Bar Via Group Simplification New Via Metals and Bar Via Loss INDEX

9 Chapter 1 The Analysis Box Chapter 1 The Analysis Box Metal Box Top The Sonnet six-sided shielding box. The metal walls of the box are transparent to allow you to see the interior of the circuit. Metal Side Walls The Sonnet EM analysis is performed inside a six-sided metal box as shown above. This box contains any number of dielectric layers which are parallel to the bottom of the box. Metal polygons may be placed on levels between any or all of the dielectric layers, and vias may be used to connect the metal polygons on one level to another. The four sidewalls of the box are lossless metal, which provide several benefits for accurate and efficient high frequency EM analysis: The box walls provide a perfect ground reference for the ports. Good ground reference is very important when you need S- 9

10 Keysight ADS Interface parameter data with dynamic ranges that might exceed 50 or 60 db, and Sonnet s sidewall ground references make it possible for us to provide S-parameter dynamic range that routinely exceeds 100 db. Because of the underlying EM analysis technique, the box walls and the uniform grid allow us to use fast-fourier transforms (FFTs) to compute all circuit cross-coupling. FFTs are fast, numerically robust, and map very efficiently to computer processing. There are many circuits that are placed inside of housings, and the box walls give us a natural way to consider enclosure effects on circuit behavior. As an example, a microstrip circuit can be modeled in Sonnet by creating two dielectric layers: one which represents your substrate, and one for the air above the substrate. The metal polygons for the microstrip would be placed on the metal level between these two dielectric layers. The bottom of the box is used as the ground plane for the microstrip circuit. The top and bottom of the box may have any loss, allowing you to model ground plane loss. Coupling to the Box Since the four sidewalls of the box are lossless metal, any circuit metal which is close to these walls can couple to the walls - just like what would happen if you fabricated and measured a real circuit with the same box. If you do not want to model this coupling (for example, your real circuit does not have sidewalls), then you must keep the circuit metal far away from the box sidewalls. A good rule to use is at least three to five substrate thicknesses as shown below. This circuit has a substrate of 25 mils. The spiral should be kept at least mils from the box walls. 10

11 Chapter 1 The Analysis Box All Sonnet geometry projects are composed of two or more dielectric layers. There is no limit to the number of dielectric layers in a Sonnet geometry project, but each layer must be composed of a single dielectric material. Metal polygons are placed at the interface between any two dielectric layers and are usually modeled as zero-thickness, but can also be modeled using Sonnet s thick metal model. Vias may also be used to connect metal polygons on one level to metal on another level. You will use the Dielectrics dialog box (Circuit Dielectric Layers), as shown below, to add dielectrics to your circuit. Each time a new dielectric layer is added, a corresponding metal level is also added to the bottom of the new dielectric layer. You may also add dielectric layers in the Stackup Manager. This example shows a 3-D drawing of a circuit (with the z-axis exaggerated). Please note that the pictured circuit is not realistic and is used only for purposes of illustrating the box setup. Note that the number of the metal level appears in between the dielectric layers. Dielectric Layer 0 1 Metal Level 2 Metal Bottom (Ground Plane). This is not shown in the Dielectric Layer dialog box Below is a glossary of some commonly used terms in Sonnet which relate to the box model. 11

12 Keysight ADS Interface Dielectric Layer: This refers only to dielectrics, NOT metals. In the example above, there are four dielectric layers. There is an entry for each dielectric layer in the Dielectric Layers dialog box (Circuit Dielectric Layers). Metal Level: Metal levels are modeled as zero thickness and are attached to the dielectric layer ABOVE them. In the example above, there are three metal levels in addition to the box top and bottom. Since no metal may be placed on the top of the box, it may not be accessed by the user or viewed in the project editor. The bottom of the box is referred to as the GND level and may be accessed in the project editor. It is not labeled in the dielectric window. The top and bottom of the box are lossless metal by default, but can be changed in the Box Settings dialog box (Circuit Box Settings). You can use as many different metal types as you wish on a single metal level; for instance, you may use a silver polygon and copper polygon on the same metal level. NOTE: A layer refers to a dielectric layer while level refers to the metal level which is sandwiched between the two dielectric layers. So, technically, there is no such thing as a metal layer in Sonnet. GND Level: You can place polygons on the GND level, but they have no effect because this level is already completely metalized. However, cases do exist in which you may want to place a polygon on the GND level in order to place a via or a dielectric brick there. Viewing Levels: When you view your circuit in the normal 2D view in the project editor, you are always on a particular level, as shown by the level drop list in the Project Editor tool bar as shown below. The top level is always 0 and increases as you move downward through the box. You can switch levels by using 12

13 Chapter 1 The Analysis Box your arrow keys, or using the level drop list. By default, all polygons on your present level are shown in Fill, and all polygons on all other levels are shown as dashed outlines. Level 0 is displayed in the level drop list in the project editor. The dotted outline indicates metal on the level below this one. Level 0 You may also change the view to other metal levels by using the Up One Level and Down One Level button on the project editor tool bar. The dotted polygon seen above is shown on Level 1 which is below Level 0. Level 1 As mentioned above, the metal level is associated with the dielectric layer above, such that when you delete a dielectric layer, the metal level directly below the layer is deleted. The total height of the box is determined by the sum of the thicknesses of the dielectric layers since metal is either modeled as zero-thickness or protrudes into the dielectric layer above. If you wish to model microstrip circuits, you will need to place a thick layer of air above your circuit; i.e., the topmost dielectric layer should be at least three to five times the substrate thickness. 13

14 Keysight ADS Interface 14

15 Chapter 2 Keysight ADS Interface Tutorial Chapter 2 Keysight ADS Interface Tutorial Introduction The Keysight ADS Interface allows you to use Sonnet s analysis engine, em, from within the Keysight ADS environment. This tutorial provides you with an example of a basic translation and analysis of a layout in Blink. The whole process from creating a layout to using the Sonnet model in a Keysight ADS simulation is covered. The following topics are covered: Installing Sonnet s Keysight Interface Adding the Sonnet design kit to ADS Creating the initial layout from your schematic Editing the substrate file (.matl) Analysis Box setup Setting up analysis frequencies and run options Producing a Touchstone output model Running a simulation Viewing simulation results Using your model in the Keysight ADS environment 15

16 Keysight ADS Interface This tutorial assumes that you are already familiar with using Keysight ADS. The Keysight ADS Interface is available for installation after you perform your Blink Installation. Please refer to the installation manual for your operating fsystem or instructions on installing Sonnet software NOTE: This tutorial was written for ADS 2011 or higher. If you are using ADS 2009, there is an example file, Keysight_2009, available which provides an ADS 2009 project. Instructions for ADS in the tutorial about opening files in the workspace will differ from using a project, but the Sonnet interface should function in a very similar manner, allowing you to perform the tutorial. Installing the Keysight ADS Interface 1 Open the Sonnet task bar. For Linux: Open a terminal and enter Sonnet at the prompt. For Windows: Select All Programs Sonnet Sonnet from the Windows desktop Start menu. Admin menu 16

17 Chapter 2 Keysight ADS Interface Tutorial 2 Select Admin Keysight ADS Interface Configuration from the main menu of the Sonnet task bar. The Keysight Interface Configuration dialog box appears on your display. 3 If it is not already selected, click on the Advanced Design System entry to select it. The entry is highlighted. 4 Click on the Install button to install the interface. A query box appears asking if you wish to install the interface, click on the Yes button. When the installation is complete a message is displayed Sonnet 16.xx was installed successfully for Advanced Design System xx. 5 Click on the Close button to close the Configuration dialog box. Copying the Examples 6 Copy the archived workspace Sonnet _Tutorial_wrk.7ads to your working directory. You need to copy the example Keysight_Interface using the Sonnet Example Browser to obtain the archive workspace. You may access the Sonnet Example Browser by selecting Help Browse Examples from the menu of any Sonnet application. For instructions on using the Example Browser, please click on the Help button in the Example Browser window. Save the example, which is an archived workspace, to your working directory. 17

18 Keysight ADS Interface NOTE: ADS 2009 users should use the example, Keysight_2009, which contains a project instead of a workplace. 7 Open ADS. If you do not know how to start the Keysight ADS program, please refer to your documentation. The main ADS window appears on your display. 8 Select File Unarchive from the main menu of the Advance Design System main window. A browse window appears on your display; select the archive you copied in the previous step from your working directory. The ADS Unarchive wizard appears on your display. 18

19 Chapter 2 Keysight ADS Interface Tutorial 9 Enter your working directory in the Destination Path text entry box. You may also click on the Browse button to open a Browse window in order to select the desired directory. Destination Path 10 Click on the Finish button in the Unarchive Wizard. The rest of the values in the Wizard are set correctly. When the process is complete a message telling you the file was successfully unarchived appears. The ADS main window displays the Sonnet_Tutorial_wrk workspace. 19

20 Keysight ADS Interface Adding the Sonnet Design Kit to your Workspace The Sonnet Design Kit is installed in ADS when you install the interface, but you must add the design kit to your workspace. 11 Select Design Kits Manage Favorite Design Kits from the main menu of the ADS main window. The Manage Favorite Design Kits dialog box appears on your display. In current Workspace checkbox 12 Select the In Current Workspace checkbox. Selecting this checkbox adds the identified Library Definition File to your workspace. When you select the checkbox, a query box appears asking if you wish to add the design kit sonnet_ads_dk to the workspace. 13 Click on the Yes button. The query box is closed and the checkbox shows the design kit as in your workspace. Adding the Sonnet design kit to your workspace, ensures that the Sonnet menu appears in your layout windows so you can access the Sonnet interface. Note that this process must be repeated for every workspace. 20

21 Chapter 2 Keysight ADS Interface Tutorial 14 Click on the Close button to close the Manage Favorite Design Kits window. Generating the Layout Next, we will generate a layout using the schematic view as the basis. 15 Open the schematic view of the Coupled_line_filter_basic cell from your workspace. You may need to click on the triangle in front of Coupled_line_filter_basic to expand the directory, so that you may double-click on the schematic entry to open it. The schematic appears on your display. 16 Select Layout Generate/Update Layout from the main menu of the schematic window. This command generates a layout view of your schematic. The Generate/Update Layout dialog box appears on your display. 21

22 Keysight ADS Interface 17 Click on the OK button of the dialog box. The default values are appropriate so there is no need to take any action in this dialog box. Once the dialog box is closed, a layout window is opened with the Coupled_line_filter_basic circuit displayed. Importing Setup from the Schematic If you have already defined such things as your substrate and analysis frequencies in your schematic, you can save setup time by importing these parameters into your Sonnet layout. For this example, importing from the schematic loads the properties and settings related to the substrate, component layers, and frequencies that are defined in the schematic. TIP You may also import from Momentum, although the tutorial demonstrates the import from the schematic. Importing from Momentum would import the parameters and settings used in the Momentum analysis. 22

23 Chapter 2 Keysight ADS Interface Tutorial 18 Select Sonnet Session Update from Schematic from the main menu of the layout window. A query box may appear telling you that the layout needs to be saved before importing the information. If so, click on the Yes button to continue. The information is imported and the Status dialog window appears with a report of what was imported. In this case, the import from Schematic includes the substrate, and ports (you may have to scroll to see the complete message). Status message Don t show me this again checkbox The status dialog appears in response to commands in the Sonnet Keysight ADS Interface. If you do not wish to see the Status dialog, you may select the Don t show me this again checkbox before closing the Status dialog window. Substrate The substrate settings were imported from the schematic. It s usually a good idea to check the stackup after an import to see if the settings are suitable for the Sonnet environment. 19 Select Sonnet Setup Substrate View Stackup from the main menu in the layout window. The Stackup Viewer appears on your display with the stackup for your circuit. The stackup consists of two dielectric layers with one metal level (0) in between. There are two different metal types, cond and cond2 on the metal level and a via to 23

24 Keysight ADS Interface ground. Sonnet analyzes in a six-sided metal box, the bottom of which is a metal level used as ground. The side walls are always lossless. For more information about the analysis box, please see Chapter 1: The Analysis Box Dielectric Properties If you hover over the Air dielectric layer, a pop-up, shown above, appears displaying the parameters of the dielectric layer. As you can see the thickness of the layer is 1e36 microns. This is to simulate an open environment, but since Sonnet analyzes in a six-sided box, the layer thickness should be set to a lower value to reduce the memory and processing requirements of the simulation. Also, the thickness of this layer defines the distance to the box top from metal level 0, so the thickness needs to be enough to prevent coupling between the box top and metal level. A thickness of 1000 microns should be sufficient. The definition of the stackup and materials, as well as the layer mapping from ADS to Sonnet, are defined in the Sonnet interface by the Sonnet substrate file (.matl). The stackup from the schematic or momentum is converted to a Sonnet substrate file. To change the thickness of the dielectric, you use the Substrate File setup dialog box to edit the substrate file. 24

25 Chapter 2 Keysight ADS Interface Tutorial 20 Select Sonnet Setup Substrate Edit from the main menu of the layout window. The Substrate File Setup dialog box appears on your display. Display ADS Layers by Mapped drop list ADS Layer to Sonnet Metal level mapping 21 Select Show Mapped ADS Layers from the Display ADS Layers by Mapped drop list. The appearance of the dialog box is updated and the mapping list now displays only the three ADS layers which are mapped to Sonnet. To change the mapping settings of an ADS layer, you would select it in the mapping list, then use the Edit Layer Mapping section of the dialog box. Note that these controls change 25

26 Keysight ADS Interface depending on the Drawing Type setting. For a detailed explanation of all of the controls in the Substrate File setup dialog box, please see Defining the Substrate, page 77. View Stackup button Edit Layer Mapping Mapping Checkbox Selected ADS Layer Sonnet Settings Dielectrics button Update button NOTE: After making changes to the layer mapping, dielectrics or materials, you must press the Update button so that the interface reflects those changes. 26

27 Chapter 2 Keysight ADS Interface Tutorial 22 Click on the Dielectrics button in the Substrate File Setup dialog box. The Dielectric Setup dialog box appears on your display. The Dielectrics Setup dialog box allows you to create new dielectric layers, edit the properties of existing layers and to delete dielectric layers. For a detailed explanation of the controls in this dialog box, please see Sonnet Dielectrics, page If it is not already selected, click on the first dielectric in the list to select it. This is the top dielectric of air. 27

28 Keysight ADS Interface 24 Enter a value of 1000 in the Thickness text entry box in the Edit/Define section of Dielectric Setup dialog box. This changes the thickness of the air dielectric layer to 1000 microns. Thickness text entry box 25 Click on the Update button to apply the change in thickness. If you do not click on the Update button, any changes in the dialog box are lost when you close it. Note that the entry for air in the list is updated with the new thickness. 26 Click on the OK button to close the Dielectric Setup dialog box. The dialog box is closed. No other changes need to be made in the Substrate File Setup dialog box since the other desired properties were input from the schematic. 28

29 Chapter 2 Keysight ADS Interface Tutorial 27 Click on the View Stackup button in the Substrate File Setup dialog box. The Stackup Viewer appears on your display again with the stackup for your circuit. If you hover over the Air dielectric, you see that the thickness is now 1000 microns. When you are done close the Stackup Viewer. Thickness 28 Click on the OK button in the Substrate File Setup dialog box to close the dialog box. There is no need to push the update button in the Substrate File Setup dialog box since no changes were made to the layer mapping. However, by changing the dielectric thickness, you have made changes to the substrate file; therefore, a query box appears on your display. 29 Click on the Yes button in the query window to save the changes and update the substrate file. Analysis Box As mentioned earlier in the tutorial, the analysis is performed in a shielded enclosure, a six-sided metal box, and uses a fixed grid based on a cell size which forms the basis for the rectangular meshing. You will be changing the cell size used for this tutorial. 29

30 Keysight ADS Interface In order to prevent coupling with the box walls, we set a margin to increase the box size. The margin is also used to set the reference plane lengths for any ports. Blink s Accurate solver has an automatic de-embedding capability. When invoked, the solver removes the port discontinuity and a desired length of transmission line. The reference planes instruct the Accurate solver as to the desired length of the transmission line to be removed. One reference plane length per box side may be specified but a single reference plane can be used for multiple parallel lines on the same box side. Cell Size You may also control the resolution of the meshing used by the Accurate solver for your analysis by setting the cell size. The smaller the cell size in Sonnet, the finer the resolution and more accurate the results. However, there is a trade-off in that smaller cell sizes increase the amount of memory and processing time for your analysis. Your cell size should be set to the largest size that still provides a sufficiently accurate answer. The optimal cell size should be based on the critical parameters of your circuit. In the case of this filter, the critical parameters in the x direction are 300 and 700 microns, so we use the value of 10 microns for the dimension of the cell size. In the Y direction, the width of the lines is 73 microns and the spacing between is 15 microns. The spacing is more critical and a value of 3 microns gives an exact match for the spacing, while introducing an error in the width of less than 1.5% (72 microns versus 73 microns). 30

31 Chapter 2 Keysight ADS Interface Tutorial 30 Select Sonnet Setup Analysis Box Edit from the main menu of the layout window. The Analysis Box dialog box appears on your display. The initial settings in this dialog box will depend on the settings in the Analysis Box tab of the Preferences dialog box. (Sonnet Preferences). The default margins are sufficient for this analysis, so no change needs to be made in the margins. Cell Size radio button Cell Size text entry boxes Margins For a detailed explanation of all of the control fields in the Analysis Box dialog box, please see Defining the Box, page 93. For a detailed explanation of the preferences, please see Analysis Box Preferences, page Click on the Cell Size radio button in the Analysis Box dialog box. This allows you to change the cell size; the cell size text entry boxes are enabled and the Num Cells text entry boxes are disabled. The relationship between box size, cell size and number of cells is (Cell Size) x (Num of Cells) = Box Size 31

32 Keysight ADS Interface The box size may not be directly changed unless you use the Set Custom Box feature. Changing the Cell Size or Num of Cells will change the box size while the Margins remain the same value. Calculate button 32 Enter 10 in the X Cell Size text entry box and 3 in the Y Cell Size entry box. This defines the cell size as 10 microns x 3 microns. 33 Click on the Calculate button to input the new cell size. The changes are not applied until you click on the Calculate button. Note that the Cell Size, Box Size and Num Cells entries are all updated while the Margins are unchanged. During the translation, the margins are rounded to the nearest cell size so the value entered here is not the exact distance used in your analysis. 34 Click on the OK button to close the Analysis Box dialog box. Ports ADS pins are automatically converted to Sonnet ports. A feedline the same length as the Margin is added from the box wall port to the original location of the ADS pin in the layout. 32

33 Chapter 2 Keysight ADS Interface Tutorial 35 Select Sonnet Setup Ports from the main menu in the layout window. The Ports dialog box appears on your display. Note that ADS pin 1 has been converted to Sonnet Port 1 and ADS pin 2 has been converted to Sonnet Port 2. As mentioned earlier, the reference plane length is set to the same value as the margin on that box wall. Sonnet s em has an automatic de-embedding capability. When invoked, em removes the port discontinuity and a desired length of transmission line. The reference planes instruct em as to the desired length of the transmission line to be removed. Pin 1 was on the left side of the layout, so Port 1 is placed on the left box wall. So the reference plane for Pin1 is set to the length of the Left margin. Sonnet Port Number Reference Plane Length for Port 1 No changes need to be made to the Ports. For detailed information on all of the controls in the Ports dialog box, please see Ports, page Click on the OK button to close the Ports dialog box. Analysis Frequencies In our example, there were no analysis frequencies defined in the schematic from which we generated our layout so you need to enter the analysis frequencies. For this circuit, we will do a broadband sweep by performing an Adaptive Sweep from 0.0 GHz to 50 GHz. 33

34 Keysight ADS Interface An adaptive sweep provides a fine resolution frequency sweep by performing an EM simulation at a few discrete points, and then using a rational fitting algorithm to calculate the fine resolution frequency data. You enter the desired frequency band by entering a beginning and ending frequency. Specifying an Adaptive Sweep starting at 0.0 GHz also automatically produces the data at a DC Point. The analysis engine takes the results at low frequency and extrapolates to calculate data for the DC Point. 37 Select Sonnet Setup Frequencies from the main menu in the layout window. The Frequency Plan dialog box appears on your display. There are presently no frequencies specified for the simulation. It is possible to define other types of frequency sweeps and you may have multiple entries in your frequency plan. For a detailed discussion of all of the controls in the Frequency Plan dialog box, please see Analysis Frequencies, page 123. Enabled checkbox Sweep Type droplist Entry boxes 38 If it is not already selected, select Adaptive Sweep (ABS) from the Sweep Type drop list. When you select a sweep type, the area below the drop list is configured to input the parameters for that sweep type. In this case, there are two text entry boxes to enter the beginning and ending frequency of the adaptive sweep. The Enabled check box is selected by default when adding a new sweep. This checkbox allows you to leave a sweep in the list, but not use it in a simulation, by selecting the sweep in the list and clearing this checkbox. 34

35 Chapter 2 Keysight ADS Interface Tutorial 39 Enter 0.0 in the Start text entry box and 50.0 in the Stop text entry box. This defines an adaptive sweep from 0.0 GHz to 50.0 GHz. 40 Click on the Add button, to add the sweep to the Enabled Type Range list. The list is updated with the adaptive sweep as shown below. As mentioned earlier, specifying a start frequency of 0.0 GHz also produces results for a DC Point. Adaptive Sweep 41 Click on the OK button to close the Frequency Plan dialog box. Subsectioning and Analysis Options As mentioned earlier in the tutorial, the Sonnet subsectioning is based on a uniform grid made up of cells. One or more cells are automatically combined together to create subsections. Since multiple cells are combined together into a single subsection, the number of subsections is usually considerably smaller than the number of cells. This is important because the analysis solves an N X N matrix where N is the number of subsections. A small reduction in the value of N results in a large reduction in analysis time and memory. Em automatically places small subsections in critical areas where current density is changing rapidly, but allows larger subsections in the less critical areas, where current density is smooth or changing slowly. There are settings which allow you to modify the automatic algorithm which we use for this tutorial. Before making any changes to the automatic algorithm, you will view the subsectioning of the circuit. The analysis engine, em, allows you to subsection your circuit without running an analysis to get an estimate of memory use. Viewing the subsectioning can also be used as a pre-simulation check to ensure that the analysis will run in an acceptable amount of time. 35

36 Keysight ADS Interface 42 Select Sonnet Tools View Subsections from the main menu in the layout window. Because you have made changes to your circuit, a query window appears to ask if you wish to translate the layout into a Sonnet project and continue. 43 Click on the Yes button to translate the design and continue. The circuit is subsectioned and when that is complete, the Estimate Memory Results window and the Sonnet Subsection viewer appear on your display. The Estimate Memory Results window supplies you with the information generated by subsectioning the circuit. For this circuit, the Estimated memory required for the analysis is 72 MB and the subsections required are 4,091. The Sonnet Subsection viewer displays the subsectioning which will be used for the analysis, as shown below. As you can see, the subsections are concentrated in the areas, such as the diagonal traces, where the current is changing rapidly. 36

37 Chapter 2 Keysight ADS Interface Tutorial Larger subsections are used on the interior of the horizontal traces since the current is steady or changing slowly. When you are done, close the Estimate Memory Results window and the Subsection Viewer. 37

38 Keysight ADS Interface 44 Select Sonnet Setup Options All Options from the main menu in the layout window. The Options dialog box appears on your display. This dialog box allows you to control all of your analysis options. For details on all of the controls in this dialog box, please refer to Options, page 106. Analysis Speed/Memory Control 45 Select Coarse/Edge Meshing from the Analysis Speed/Memory Control drop list. The Speed/Memory Control allows you to control the memory usage for an analysis by controlling the subsectioning of your circuit. The high memory settings produce a more accurate answer and usually increase processing time. This is the default setting. Conversely, a low memory setting runs faster but does not yield as accurate an answer. You will use the middle setting, Coarse/Edge Meshing. This setting is often a good compromise between speed and accuracy. The edges of the polygons have small subsections, but the inner portions of the polygons have very large subsections. Since model creation is selected by default, you do not need to make any other changes in this dialog box. 38

39 Chapter 2 Keysight ADS Interface Tutorial 46 Click on the OK button to close the dialog box and apply the changes. 47 Select Sonnet Tools View Subsections from the main menu in the layout window. This time, with the Coarse/Edge Meshing setting being used, the Estimate Memory results shows 31 MB and 2,355 subsections. Both requirements have been reduced by approximately 50%. The subsectioning shows the concentration of smaller subsections on the edges and larger subsections on the interior of polygons. 48 Close the Estimate Memory Results window and the subsection viewer. Connectivity Checker Blink has a tool, the Connectivity Checker, available in the project viewer which allows you to visually check for opens or shorts in your circuit. You may invoke the tool directly from the Keysight ADS Interface window. This tool is especially useful after translating to make sure that the metal placement has not created any opens or shorts. 39

40 Keysight ADS Interface 49 Select Sonnet Tools Check Connectivity from the main menu of the Sonnet Cadence Virtuoso Interface window. Sonnet s project viewer appears on your display with the Connectivity Checker on. 50 Click on any polygon in the middle trace of the circuit. The polygon you selected in the middle trace is highlighted in red, as well as any metal to which it is electrically connected. In our case, no other metal should be highlighted. If another part of the circuit was highlighted this would indicate there was a short between the coupled lines. Clicking on the top and bottom traces will show that all of the polygons are electrically connected and touching the box wall on the ends. 40

41 Chapter 2 Keysight ADS Interface Tutorial 51 Press the Escape key to exit the Connectivity Checker. The view is updated to show the 2D view. Note that you are looking directly down from the top of the box in this view. The size of the box is shown by the black outline. You can also see the feedlines and reference planes (indicated by the black arrows extending from the ports) added automatically to your circuit. The original layout from ADS is highlighted in the graphic with a red outline. Feedline for Port 1 Original Layout from ADS TIP You may also see the 2D view by selecting Sonnet Tools Project Editor/ Viewer View 2D from the main menu of the ADS layout window. Another useful tool is the 3D viewer which allows you to see all the metal levels in your circuit at once from any angle. To see the 3D view, select Sonnet Tools Project Editor/Viewer View 3D from the main menu of the ADS layout window. 52 Select File Exit from the main menu of the Sonnet project viewer. The project viewer is closed. Now that setup is complete and you have checked your translated circuit, you are ready to run the simulation. 41

42 Keysight ADS Interface Simulation When you run a simulation, your circuit is translated into a Sonnet project and em is evoked. For an ABS sweep, the Accurate solver analyzes the circuit at the beginning and end frequencies. Using an iterative process, the solver then analyzes at other discrete frequencies and determines a rational polynomial fit to the S-parameter data within the frequency band. Once a rational polynomial fit is achieved with an acceptable error, the frequency response across the specified bandwidth is calculated. The output data consists of the discrete data points, frequencies at which the solver performs a full electromagnetic analysis, and the adaptive data, which is data calculated using the rational polynomial. Since our frequency band begins at 0.0 GHz, once the adaptive data is calculated, the solver then extrapolates from the results to produce data for a DC point. TIP For longer analysis runs, you may want to make the license for the Sonnet Keysight ADS interface available in order to work on another project or to allow another user access to the interface. See Simulate and Release, page

43 Chapter 2 Keysight ADS Interface Tutorial 53 Select Sonnet Analysis Simulate from the main menu of the Sonnet Cadence Virtuoso Interface window. The Sonnet analysis is launched and the Progress of Sonnet Simulation window appears on your display to indicate the progress of the simulation. When the simulation is complete, the model and dataset are created. The hpeesofsim window appears to report on the creation of the dataset. 43

44 Keysight ADS Interface Once the dataset has been created, the Keysight ADS plot window is opened. If a plot has been specified, the data is shown. The plot of DB[S11] and DB[S21] for the analysis is shown below. Viewing Results in Sonnet You may also examine the results of your simulation in the native environment s response viewer. 44

45 Chapter 2 Keysight ADS Interface Tutorial 54 Select Sonnet Results View Response from the main menu of the Sonnet Cadence Virtuoso Interface window. Sonnet s response viewer appears on your display with the default plot of DB[S11] displayed. Curve Group 45

46 Keysight ADS Interface 55 Double-click on the curve group in the Left Axis section of the legend. The Edit Curve Group dialog box is opened for the Sonnet_Tutorial_lib_Coupled_line_filter_basic_SonnetEM curve group. DB[S21] 56 Double-click on the DB[S21] entry in the Unselected list. This moves DB[S21] to the selected list. DB[S21] 46

47 Chapter 2 Keysight ADS Interface Tutorial 57 Click on the OK button in the Edit Curve Group dialog box to apply the changes and close the dialog box. The plot in the response viewer is updated to display both DB[S11] and DB[S21] As you can see, the plot matches the hpessof plot shown earlier. DB[S11] Adding a Marker Sonnet s response viewer allows you to place a marker to label important data points in your plot. In this section, you will add a marker to identify the minimum point of DB[S11] and the frequency at which it occurs. 58 Select Graph Marker Add Data Marker from the main menu of the response viewer. The appearance of your cursor changes: TIP Note that when you are over a data point in your plot, the box that is part of the cursor appears in reverse video (black with a white A. ) 47

48 Keysight ADS Interface 59 Click on the lowest point of the DB[S11] curve. When you select the data point, a label M1 appears as well as a another label which displays the value of the data point and the frequency at which it occurs. Note that once you add the marker, you may drag the data display box to any location on your plot. The minimum of DB[S11] whose value is occurs at 36.8 GHz. Data Marker 60 Select File Exit from the main menu of the response viewer. The response viewer is closed. For more information on the response viewer s features, please refer to Sonnet Help by selecting Help Sonnet Help from the main menu of the response viewer or click on the Help button in any dialog box. Viewing the Model The S-Parameter Model is in Touchstone format and is created at the end of a Sonnet simulation when you use the Simulate command. Once you have successfully analyzed your project in Sonnet, you create an S-parameter model which you can use as a component in your ADS project. The name of the model is the basename of your design with SonnetEM_SParamModel. So the cell of the model name for this tutorial is: Coupled_line_filter_basic_SonnetEM_SParamModel 48

49 Chapter 2 Keysight ADS Interface Tutorial This design contains schematic, layout and symbol views. You may access these views through the Sonnet menu in the layout window. The layout view is identical to the layout from which the model was generated. 61 Select Sonnet Models View S-Parameter Model Schematic from the main menu of the layout window. The schematic view of the model is opened on your display. Note that the schematic view lists the raw data file for the model. Model Data File 49

50 Keysight ADS Interface 62 Select Sonnet Models View S-Parameter Model Symbol from the main menu of the layout window. The symbol view of the model is opened on your display. This symbol is a layout look alike. You use this symbol to represent the model created by the analysis in your ADS designs. Using the Model The last part of the tutorial demonstrates how to use the model in an ADS simulation and verifies the results. 50

51 Chapter 2 Keysight ADS Interface Tutorial 63 In the main ADS window, open the schematic view in the Comparison_tb in your workspace. This cell was provided as part of the example files for the tutorial. Schematic cell in Comparsion_tb cell The schematic appears on your display. The two circuits in the schematic, top and bottom, are identical, except that the top schematic uses the original coupled_line_filter_son schematic while the bottom circuit uses the Sonnet model produced by your Sonnet analysis. X1 Sonnet model symbol 51

52 Keysight ADS Interface 64 Click on the X1 component in the top circuit to select it. The X1 substrate is highlighted with a gray square. Push into hierarchy button X1 Component I_1 Component 52

53 Chapter 2 Keysight ADS Interface Tutorial 65 Click on the Push into Hierarchy button in the tool bar of the schematic window. This opens the X1 component in the window; as you can see it is identical to the original Coupled_line_filter_basic schematic. Pop Out button 66 Click on the Pop Out button in the tool bar of the schematic window. The view returns to the original schematic showing the two circuits. 53

54 Keysight ADS Interface 67 Click on the I_1 component in the bottom circuit, then click on the Push into Hierarchy button. The schematic view of the Sonnet model created by your analysis is displayed in the window. 68 Click on the Pop Out button to return to the full schematic view. The analysis has already been set up in the schematic and an output plot defined. The frequency band is from 0.0 GHz to 50 GHz. 54

55 Chapter 2 Keysight ADS Interface Tutorial 69 Select Simulate Simulate from the main menu in the schematic window. The simulation is launched and when it is complete, a plot appears on your display. This plot compares the results of the two circuits. The Sonnet model is shown in red and the original schematic is shown in blue. As you can see there is a reasonable match. This completes the Keysight ADS Interface tutorial. 55

56 Keysight ADS Interface 56

57 Chapter 3 Keysight ADS Interface Chapter 3 Keysight ADS Interface Sonnet s plug-in for Keysight s Advanced Design System (ADS) enables the designer to configure and run the EM analysis from a layout, and extract accurate electrical models. The Keysight ADS Interface provides a seamless translation capability between Sonnet and Keysight s ADS. From within the ADS Layout, you can directly create Sonnet geometry files. Em simulations can be invoked and the results incorporated into your design without leaving the ADS environment. This manual assumes that you are familiar with the basics of using both Sonnet and ADS. If this is not true, we recommend referring to the appropriate documentation for whichever program you need to learn. If you are new to Sonnet, we suggest performing the tutorials in the Getting Started with the Native Environment manual, available in PDF format through the Sonnet task bar. NOTE: The Keysight ADS Interface only supports geometry projects. It is not possible to translate a netlist project from Sonnet. 57

58 Keysight ADS Interface The illustration below shows how the Keysight ADS Interface relates to the Sonnet suite. Keysight ADS Sonnet Native Environment Keysight ADS structure Instance Models AI Keysight ADS Interface Project Editor Circuit Geometry Analysis Electromagnetic Simulation System Requirements For up to date requirements and testing status, please refer to: Licensing The Keysight ADS Interface is only available if you have purchased an Keysight ADS Interface License from Sonnet. The Keysight ADS Interface is included in your Blink package. Changes in ADS Project Organization Keysight enacted major organizational changes in the upgrade from ADS 2009 to ADS In ADS 2009, a user worked with a project while in ADS 2011 and higher, the user has a workspace. The project contained various designs, while a workspace is made up of cells that can have multiple views and are part of a library. Very little has changed in the Sonnet Keysight ADS Interface but there are several details of which you should be aware. 58

59 Chapter 3 Keysight ADS Interface Projects versus Workspaces Shown below is a comparison of an ADS 2009 file directory for a project versus the file directory for a 2011, or higher, workspace along with a schematic of an output model from a Sonnet simulation. Projects contained designs and design representations while workspaces contain cells and cell views that are part of a library. When working with ADS 2009, the Sonnet Keysight ADS interface is used to create the types of design representations: layout, schematic and symbol. When ADS 2011 is used, the Sonnet interface creates a new cell with layout, schematic and symbol views. ADS 2009 Project Design Model Schematic of Sonnet output 59

60 Keysight ADS Interface Filename Model Schematic of Sonnet Output - ADS

61 Chapter 3 Keysight ADS Interface ADS 2011 or higher Workspace Cell Cell Views Cell created by a Sonnet simulation Schematic view of Sonnet cell 61

62 Keysight ADS Interface Schematic Cell View of Sonnet output - ADS 2011 or higher Filename Installation for ADS 2009 The manual installation of Sonnet s Keysight ADS Interface using ADS 2009 is different from the procedures when using the interface with ADS 2011 or higher. If you are using ADS 2011 or higher, please refer to Installation for ADS 2011 and Higher, page 69. If you are using ADS 2009, please refer to the Installation instructions below. If Keysight s ADS is already installed on your system, then the Keysight ADS Interface is automatically installed when you install your Sonnet Software. If you need to install the Keysight ADS Interface after Sonnet is installed, you may do so from either the Sonnet or ADS environment. Directions for both are below. Manual Installation Using Sonnet To install the Keysight ADS Interface from the Sonnet environment, do the following: 62

63 Chapter 3 Keysight ADS Interface 1 Select Admin Keysight ADS Interface Configuration from the main menu on the Sonnet task bar after you have installed Keysight s ADS. The Keysight ADS Interface Configuration window appears on your display and lists all the versions of ADS which are available. This example shows only one instance of ADS. If there is more than one version of ADS available, click on the desired version to enable the Install button. 2 Click on the Install button at the bottom of the window. A query appears on your display asking if you wish to proceed. 63

64 Keysight ADS Interface 3 Click on the Yes button. The Keysight ADS Interface is installed. A success message is displayed, and the window is updated to show that it is installed as shown below. Manual Installation Using ADS To install the Keysight ADS Interface from the ADS environment, follow the instructions below. 64

65 Chapter 3 Keysight ADS Interface 1 Invoke ADS. The ADS main window appears on your display. DesignKit menu 2 Select DesignKit Install DesignKits from the menu. The Install ADS DesignKit dialog box appears on your display. Browse button for the Path Path text entry box 3 Click on the Browse button to the right of the Path text entry box and select the Sonnet Design Kit directory in the Sonnet installation. The Sonnet Design Kit directory is found at < Sonnet Directory >\sonnet_ads_dk where < Sonnet Directory > is the directory in which Sonnet software was installed. 65

66 Keysight ADS Interface 4 Click on OK in the Browse window. The Install ADS Design Kit dialog box is updated and should appear as shown below: 5 Click on OK in the Install ADS Design Kit dialog box to close the dialog box and install the Design Kit. 6 To check the installation, select DesignKit List Design Kit. The List ADS Design Kits dialog box appears; check to ensure that the design kit SONNET_ADS_DK appears in the list. This completes the installation of Sonnet s Keysight ADS Interface. Automatic Uninstall The Keysight ADS Interface is not automatically uninstalled when you uninstall Sonnet Software. To uninstall only the Keysight ADS Interface you may do so manually from either the Sonnet environment or the ADS environment. 66

67 Chapter 3 Keysight ADS Interface Manual Uninstall Using Sonnet To uninstall the Keysight ADS Interface in the Sonnet environment, do the following: 1 Select Admin Keysight ADS Interface Configuration from the main menu on the Sonnet task bar. The Keysight ADS Interface Configuration window appears on your display. 2 Click on the version of ADS in the list which you wish to uninstall. The entry is highlighted and the Uninstall button is enabled. 3 Click on the Uninstall button. The installed column for that entry is updated to say <not installed>. Manual Uninstall Using ADS If you need to uninstall the Keysight ADS Interface but do not have access to the Sonnet task bar, you may do so manually by following the instructions below. 1 Invoke ADS. The ADS main window appears on your display. DesignKit menu 67

68 Keysight ADS Interface 2 Select DesignKit Setup DesignKits from the menu. The Setup ADS DesignKit dialog box appears on your display. Sonnet DesignKit Cut Button 3 Click on the SONNET_ADS_DK entry in the Overview list. The entry is highlighted to indicate that it is selected. The Design Kit information on the right side of the dialog box is updated with the information pertaining to the Sonnet DesignKit. 4 Click on the Cut button to remove the Sonnet DesignKit. The Sonnet entry is removed from the Overview list. 5 Click on the OK button to close the Setup ADS Design Kits dialog box and apply the change. You should exit ADS, and restart the program to complete the uninstall. 68

69 Chapter 3 Keysight ADS Interface Installation for ADS 2011 and Higher The manual installation of Sonnet s Keysight ADS Interface using ADS 2011 or higher is different from the procedures when using the interface with ADS If you are using ADS 2009, please refer to Installation for ADS 2009, page 62. If you are using ADS 2011 or higher, please refer to the Installation instructions below. If Keysight s ADS is already installed on your system, then the Keysight ADS Interface is automatically installed when you install your Sonnet Software. If you need to install the Keysight ADS Interface at a later time, you may do so from the Sonnet environment. Directions are below. Manual Installation Using Sonnet To install the Keysight ADS Interface from the Sonnet environment, do the following: 1 Select Admin Keysight ADS Interface Configuration from the main menu on the Sonnet task bar after you have installed Keysight s ADS. The Keysight ADS Interface Configuration window appears on your display and lists all the versions of ADS which are available. This example shows only one instance of ADS. If there is more than one version of ADS available, click on the desired version to enable the Install button. 69

70 Keysight ADS Interface 2 Click on the Install button at the bottom of the window. A query appears on your display asking if you wish to proceed. 3 Click on the Yes button. The Keysight ADS Interface is installed. A success message is displayed, and the window is updated to show that it is installed as shown below. Manual Installation Using ADS When manually installing a Design Kit in the ADS 2011 environment, there is an issue with pathnames that contain spaces that causes the installation of a Design Kit to fail. Since the default location for a Sonnet installation contains spaces in the pathname, installing the Sonnet Design Kit in the ADS environment normally 70

71 Chapter 3 Keysight ADS Interface fails. We strongly suggest installing Sonnet s Keysight ADS Interface in the Sonnet environment as documented in "Manual Installation Using Sonnet" on page 69 to ensure that the Sonnet Design Kit is properly installed. Adding the Sonnet Design Kit When using ADS 2009, once you installed the Sonnet Keysight ADS Interface as a Design Kit, the interface was automatically available for any new project. In ADS 2011 and higher, the Sonnet Design Kit must be added to each desired workspace in order to use the Sonnet Keysight ADS Interface in that workspace. For detailed installation instructions, please see Installation for ADS 2011 and Higher, page 69. You may choose to add the Sonnet Design Kit to a workspace when creating the workspace or you may add it to the workspace later. Instructions for both methods are provided below. Adding the Sonnet Design Kit when Creating a Workspace To add the Sonnet Design Kit to a workspace when you create the workspace, do the following: 1 In the main ADS window, select File New Workspace from the menu. The New Workspace Wizard appears on your display. If it opens on the Introduction page, please click on the Next button. 71

72 Keysight ADS Interface 2 In the Workspace Name page of the Wizard, enter the desired workspace name and location. Workspace Name Workspace Location 3 Once you have finished specifying these fields, click on the Next button. The Add Libraries page of the wizard appears on your display. 4 Click on the SONNET_ADS_DK checkbox on the Add Libraries page. 72

73 Chapter 3 Keysight ADS Interface Selecting the SONNET_ADS_DK checkbox automatically selects the User Favorite Libraries and PDKs checkbox. Selecting this checkbox installs the Sonnet Keysight ADS Interface in this workspace. Sonnet Design Kit checkbox 5 Click on the Finish button. This closes the Wizard and creates the new workspace with the Sonnet Interface installed. Please note that you could have also chosen to click on the Next button to manage the libraries for the new workspace, but that step is not necessary to include the design kit, so it was not shown. Adding the Sonnet Design Kit to an existing Workspace To add the Sonnet Design Kit to an existing workspace, do the following: 1 Select the workspace in the ADS main window. 73

74 Keysight ADS Interface 2 Select Design Kits Manage Favorite Design Kits from the menu of the main window. The Manage Favorite Design Kits dialog box appears on your display as shown below. Note that if you have multiple design kits installed, they will also be listed in this dialog box; our example shows only the Sonnet design kit. Current Workspace checkbox 3 Click on the Current Workspace checkbox in the SONNET_ADS_DK entry line to select the Sonnet design kit. A query window appears on your display. 4 Click on the Yes button in the query window. The window closes and this completes adding the design kit. 5 Click on the Close button in the Manage Favorite Design Kits dialog box to close it. 74

75 Chapter 3 Keysight ADS Interface Automatic Uninstall The Keysight ADS Interface is not automatically uninstalled when you uninstall Sonnet Software. To uninstall only the Keysight ADS Interface you may do so manually from either the Sonnet environment or the ADS environment. Manual Uninstall Using Sonnet To uninstall the Keysight ADS Interface in the Sonnet environment, do the following: 1 Select Admin Keysight ADS Interface Configuration from the main menu on the Sonnet task bar. The Keysight ADS Interface Configuration window appears on your display. 2 Click on the version of ADS in the list which you wish to uninstall. The entry is highlighted and the Uninstall button is enabled. 3 Click on the Uninstall button. The installed column for that entry is updated to say <not installed>. Manual Uninstall Using ADS If you need to uninstall the Keysight ADS Interface but do not have access to the Sonnet task bar, you may do so manually by following the instructions below. 1 Invoke ADS. The ADS main window appears on your display. DesignKit menu 75

76 Keysight ADS Interface 2 Select DesignKits Manage Favorite DesignKits from the menu. The Manage Favorite Design Kits dialog box appears on your display. Sonnet Design Kit Remove from List button 3 Click on the SONNET_ADS_DK entry in the Design Kits list. The entry is highlighted to indicate that it is selected. 4 Click on the Remove from List button to remove the Sonnet Design Kit. A window appears with the message Are you sure you want to remove the selected kits? 5 Click on the Yes button in the query window. The Sonnet entry is removed from the Design Kit list. 6 Click on the Close button to close the Manage Favorite Design Kits dialog box. You should restart ADS to complete the installation. 76

77 Chapter 3 Keysight ADS Interface Accessing Sonnet s Keysight ADS Interface In order to use Sonnet as your electromagnetic analysis engine, you must create a layout view of the design or a part of a design that you wish to simulate in Sonnet. Once you open the layout view, you may use the Sonnet menu in the layout view window to set up and simulate the circuit in Sonnet. The layout window with the Sonnet menu open is shown below. Defining the Substrate Once you have opened the layout view, you need to define the mapping from ADS to Sonnet and the materials and dielectric layers to be used in your Sonnet em analysis. All of these elements make up the definition of the substrate. You use the Substrate File Setup dialog box, shown below, to control these settings. You open the dialog box by selecting Sonnet Setup Substrate Edit from the Sonnet menu in the layout window. The main window allows you to define the mapping from ADS to Sonnet. Before you set up the mapping, you 77

78 Keysight ADS Interface should first set up the Sonnet environment to which you will map your ADS layers This consists of setting up the Sonnet Materials (Metal Types) and the Sonnet Layers. Mapping Parameters List of ADS Layers Dielectrics button Materials button Sonnet Materials The Sonnet Material Setup dialog box allows you to define metal types for your Sonnet project. Once these materials are defined, they may be used to map ADS 78

79 Chapter 3 Keysight ADS Interface objects when translating. The Sonnet Material Setup dialog box, shown below, is opened when you click on the Materials button in the Substrate File Setup dialog box. List of defined materials. Enter the parameters for new materials in this part of the dialog box. The defined materials (planar and via metal types in Sonnet) are listed in the dialog box. Lossless is the default metal used in all Sonnet projects and may not be deleted. To add a new metal type, fill in the fields on the right side of the dialog box and then click on the Add button. The new material will appear in the list. A detailed discussion of the entries is below. For a detailed discussion of metal types and metal loss, please see Chapter 3 "Metalization and Dielectric Layer Loss" on page 41 in the Native Environment User s Guide. TIP Selecting any material in the list will update the entry section of the dialog box, allowing you to edit the materials parameters if necessary. 79

80 Keysight ADS Interface Name: Enter the desired name for this metal type in this text entry box. This name must be unique to the metal type (either planar or via); no duplicate names are allowed. A via metal type and planar metal type may have the same name. Type: Sonnet has two different metal types: planar for metal polygons and via for via polygons. Select Planar or Via from this drop list to identify which type of metal you are creating. Model: Select the metal definition you wish to use for this metal type. The choices in this drop list are different, depending on what is selected in the Type drop list. Both sets of choices are explained below. Planar metal: The appearance of the dialog box will change based on which definition Type you choose. You may select one of the following: Normal, ThickMetalModel, Resistor, R dc /R rf, General, RoughMetal, or SenseMetal. Enter the parameters that define the metal in the text entry boxes below. For a detailed explanation of the planar metal type loss models and their parameters, please see "Planar Metalization Loss" on page 42 of the Native Environment User s Guide. Via metal: The appearance of the dialog box will change based on which definition Type you choose. You may select one of the following: Volume, Surface or Array. Enter the parameters that define the metal in the text entry boxes below. For a detailed explanation of the via metal type loss models and their parameters, please see "Via Metalization Loss" on page 52 of the Native Environment User s Guide. Pattern: Enter an index number to identify the pattern used to represent this metal type in Sonnet s project editor. Each planar metal type should be assigned a different metal pattern from other planar metal types. Each via metal type should be assigned a different metal pattern from other via metal types. You may assign the same pattern number to a planar metal type and a via metal type if they are the same type of metal, Gold for example.the patterns will be shown as reverse video of each other. When you click on the Add button the entry for this metal type is updated in the Sonnet Material Setup dialog box. If you wish to edit the parameters of a metal type, click on its entry in the list, then edit the values. When you are done, click on the Update button. To delete a metal type, click on the desired metal type, then click on the Delete button. To delete all the metal types, click on the Clear All button. This deletes all metal types, except for Lossless planar metal and Lossless via metal. For a list of all metal types and 80

81 Chapter 3 Keysight ADS Interface their properties, click on the Summary button. This will open a window containing details about all the metal types defined. If you need to keep a hardcopy of the list, you may click on the Print button. Sonnet Dielectrics The Sonnet Dielectric Setup dialog box allows you to define the dielectric layers and metal levels for your Sonnet project. Once these dielectrics are defined, they may be used as a destination for layers being mapped from ADS. The Sonnet Dielectric Setup dialog box, shown below, is opened when you click on the Dielectrics button in the Substrate File Setup dialog box. List of defined dielectrics Enter the parameters for new dielectrics in this part of the dialog box. 81

82 Keysight ADS Interface The dielectric layers are listed in the dialog box. Sonnet circuit geometry consists of alternate dielectric layers and metal levels enclosed in a six-sided metal box. Each time you add a dielectric layer you add a metal level. It is important to note that the metal level is associated with the dielectric layer ABOVE it. If that dielectric layer is deleted from the circuit, then the metalization below it is also deleted and this will change the ADS to Sonnet mapping. The default for a Sonnet project is a two layer circuit with two metal levels GND and Level 0. Sonnet Level Numbering in a 3 layer circuit. To add a dielectric layer, click on an existing dielectric layer in the list, then enter the parameters for the layer you wish to add. The type of dielectric is specified for each dielectric layer by entering the dielectric constant and loss parameters in this dialog box. For details about these parameters, see Dielectric Layers in online Help in Sonnet. Online help may be accessed by selecting Help Sonnet Help from the Sonnet task bar or any Sonnet application. Once you have entered the desired parameters, click on the Add button to add a dielectric layer. The new layer will be added BELOW the layer presently selected in the layer list. If you wish to move the location of the layer, select the layer in the list, then click on the Move Up or Move Down button in the Layer Setup dialog box to change this layer s position in the circuit. #: This is the number of the dielectric layer. You may not edit this value. The positions of layers must be changed using the Move Up or Move Down buttons. 82

83 Chapter 3 Keysight ADS Interface Name: Enter the desired name for the dielectric material to be used in the layer here. Conductivity: Dielectric conductivity, σ, where σ is the conductivity of the dielectric. The default unit is S/m. You may define your dielectric loss using conductivity or resistivity. To use conductivity, you should select Conductivity from the Specify Using drop list. Resistivity: Resistivity = 1.0 / conductivity. Resistivity has a default unit of Ohm-cm.You may define your dielectric loss using conductivity or resistivity. To use resistivity, you should select Resistivity from the Specify Using drop list. Thickness: Enter the desired thickness of the dielectric layer here. Erel: Enter the relative dielectric constant here. DLoss: Enter the dielectric loss tangent here. Cond (S/M): Enter the dielectric conductivity here. Mrel: Enter the relative magnetic permeability here. MLoss: Enter the magnetic loss tangent here. When you click on the Add button, the entry for this dielectric layer is updated in the Sonnet Dielectric Setup dialog box. If you wish to edit the parameters of a dielectric layer, click on its entry in the list, then edit the values in the right hand side of the dialog box. When you are done, click on the Update button. To delete a dielectric, click on the desired dielectric, then click on the Delete button. To delete all the dielectrics, click on the Clear All button. This deletes all the dielectrics except GND and zero, which will be set to the default values. For a list of all dielectric layers and their properties, click on the Summary button. This will open a window containing details about all the dielectrics. If you need to keep a hardcopy of the list, you may click on the Print button. When you have completed adding or changing dielectric layers, click on the OK button to apply the changes and close the dialog box. 83

84 Keysight ADS Interface Mapping from ADS to Sonnet This section of the Substrate File setup window controls how the drawing layers from ADS are mapped into Sonnet metal levels. The ADS layers listed are those associated with the layout in which you are presently working. You may control what ADS layers are displayed by using the drop down lists in the Display ADS Layers section of the window. To change the mapping of an ADS layer, select the entry in the Mapping list. Note that the ADS layer name has no relationship to Sonnet s dielectric layer number or metallization level number. You may not edit this entry. To map the ADS layer, you use the Edit Layer mapping section of the Substrate File Setup window as shown below. Edit Layer Mapping Mapping Checkbox Selected ADS Layer Sonnet Settings TIP Mapping from ADS to Sonnet should be done after the Materials and Dielectrics in Sonnet have been defined. See Sonnet Materials, page 78 and Sonnet Dielectrics, page

85 Chapter 3 Keysight ADS Interface Displaying ADS Layers There are two drop down lists that control what ADS layers appear in the list. The left-hand drop list controls whether you list visible ADS layers, invisible ADS layers, or both. The right-hand list controls whether you display mapped layers, unmapped layers, or both. Choosing a different selection in either of these drop lists will update the list of ADS layers below. TIP You may map two ADS layers to the same Sonnet level. Selecting an ADS layer to Map to Sonnet If you wish to map an ADS layer to Sonnet, click on the desired ADS layer in the list. The number and name of the layer will appear in the Edit Layer Mapping section of the Substrate Setup File window as shown below. Click on the map checkbox to map the displayed ADS layer to Sonnet. The next section discusses the Sonnet Settings. The number and name of the ADS layer presently selected in the ADS layer list. You may not edit these values. To map another layer, select it in the list and these fields will be updated. Map Checkbox Sonnet Settings Sonnet Settings These controls affect how the layer is mapped to the Sonnet project. 85

86 Keysight ADS Interface Drawing Type: This will map objects on the ADS layer identified above to the Sonnet project. This drop list allows you to select what type of object should be input to the Sonnet project. Select Metal for metalization, or Via for a via polygon from the drop list. If you select Via, then the To Drawing Level drop list appears (see following). XMin, XMax, YMin, YMax: Sonnet allows you to control how cells are combined into subsections for each polygon. This is done using the parameters X min, Y min, X max and Y max. These fields are applied as a global setting for all polygons on the selected mapped layer. For a detailed discussion of these parameters and how they affect subsectioning in Sonnet, please refer to "Changing the Subsectioning of a Polygon" on page 29 of the Native Environment User s Guide. Use Edge Mesh: This checkbox only appears when the Drawing Type (see above) is set to Metal. Select this checkbox to turn on edge meshing for all polygons on the level being mapped. When using the Edge Mesh option, all Manhattan polygons (no diagonal edges) are treated as if they were non- Manhattan polygons. In other words, the edge subsections are always one cell wide regardless of X Min or Y Min. When used in conjunction with large X Min or Y Min values, this option can be very useful in reducing the number of subsections but still maintaining the edge singularity. This is very often a good compromise between accuracy and speed. This control is not applicable if the fill type is Conformal. Add Via Pads: This checkbox only appears when the Drawing Type (see above) is set to Via. Selecting this option adds a metal polygon of the same size and shape as the via to the bottom and top of the via. Drawing Level: This specifies the level in the Sonnet project where you wish to place the object being input from ADS. The top level is number 0. To put metal on the ground plane, for via placement, set the level to GND. If the object is a via, this defines the origin of the via. The number of levels are defined using the Sonnet Dielectrics Setup dialog box. For details, see Sonnet Dielectrics, page 81. To Drawing Level: This drop list is only enabled if the Drawing Type is a Via. Select the level to which you wish the via to extend. The origin of the via is selected in the Drawing Level drop list. Values range from GND for ground up to TOP for the box top. 86

87 Chapter 3 Keysight ADS Interface Metal Material: Select the metal material type you wish to use for the object in the Sonnet project translated from the ADS layer. This drop list only appears if your Drawing type is Metal. The choices available depend on what materials have been defined. Materials are defined using the Sonnet Materials dialog box. For more information, see "Sonnet Materials" on page 78. Metal Fill Type (Mesh): This drop list only appears if the Drawing Type is Metal. This drop list controls the fill type in Sonnet for any metalization that is present on the ADS layer. The fill type of a polygon is defined as subsectioning used by em to model the polygon. The four options in the drop list are defined as follows: Fill Type Default Staircase Diagonal Conformal Description The metalization will use the fill type selected in the Keysight Interface Options. See "Options" on page 106 for details. Provides the best rectangular fit to the metalization edge. Staircase subsections are used in the middle of a polygon for all choices. Sonnet defaults to staircase edge fill for all new metal structures. Allows triangular as well as rectangular subsections. This provides a better fit to diagonal edges but requires more analysis time. This applies conformal meshing to the selected polygon(s). This allows for larger conformal sections which model curved edges more efficiently. 87

88 Keysight ADS Interface Via Fill Type (Mesh): This drop list only appears if the Drawing Type is Via. This drop list controls the fill type in Sonnet for any vias that are present on the ADS layer. The fill type of a polygon is defined as subsectioning used by em to model the polygon. The four options in the drop list are defined as follows: Fill Type Ring Vertices Center Full Description This is the recommended meshing fill type for modeling both solid and hollow vias. The via is modeled as a one cell wide wall of via subsections and is hollow in the middle, containing no metal. Note that when used in conjunction with the Volume loss model, both the DC and RF affects are accurately taken into account. Models the via by placing a single cell wide via subsection at each vertex of the polygon. Notice that if you use this model, the current may need to travel a longer path (i.e., longer than the real circuit) before it reaches the via. Therefore, you should use this setting if you are not concerned about the accuracy of the via but want a reasonable approximate model. A single cell wide via subsection is placed in the center of the via polygon. Notice that if you use this model, the current may need to travel a longer path (i.e., longer than the real circuit) before it reaches the via. Therefore, you should use this option when you are not concerned about accuracy of the via but just want to provide a connection from one level to another. This meshing fill models the via as solid metal. All subsections in the interior of the via are filled with metal extending the length of the via. This type of meshing fill is the most costly in terms of processing time and memory. This model should only be used if the via you are modeling is actually solid and you require a high level of accuracy. Via Material: Select the via material type you wish to use for the object in the Sonnet project translated from the ADS layer. This drop list only appears if your Drawing type is Via. The choices available depend on what materials have been defined. Materials are defined using the Sonnet Materials dialog box. For more information, see "Sonnet Materials" on page 78. Once you have completed entering the parameters, click on the Update button. The entry for the ADS layer in the list will be updated. 88

89 Chapter 3 Keysight ADS Interface Sorting the ADS Layer List The sorting controls allow you to control in what order the ADS layers are displayed in the Substrate File Setup window. Select by which field you wish to sort the list from the Sort By drop list. You may choose from the following options: Sort By ADS# ADSLayer Map SonType SonLevel SonMaterial SonFillType SonOther Definition Puts them in order according to the ADS layer number. Puts them in alphabetical order according to the name of the ADS layer. Groups the mapped layers together and groups nonmapped layers together. Groups the metals by the SonType assigned to them in the mapping. Groups the metals by the SonLevel assigned to them in the mapping. Groups the metals by the SonMaterial assigned to them in the mapping. Groups the metals by the SonFillType assigned to them in the mapping. Groups the metals by the AddViaPads setting for Via metal types and by the XMin, XMax, YMin, YMax settings for planar metal types. Clearing If you wish to clear all the mapping applied to the ADS layers, click on the Clear Mapping button in the Substrate Setup File window. This will reset all ADS layers to No for mapping. If you wish to clear all substrate settings - mapping, materials, and layers - click on the Clear All button. 89

90 Keysight ADS Interface Map Used Clicking on the Map Used button will map all of the ADS layers used in the design presently in the layout window to Sonnet. Highlight Non-Hierarchical Items in Layout Select the Highlight checkbox in this section of the dialog box so that the items on the presently selected ADS layer are selected in the layout window. The number of objects that are presently highlighted in the view is displayed to the right of the checkbox. If you wish to see a full view of the layout window, click on the View All button. Summary of Mapping To see a summary of all the mapping in an easy to read format, click on the Summary button. A window listing all ADS layers and mapping information appears on your display. To print out the summary, click on the Print button. Viewing the Stackup You may open Sonnet s Stackup Viewer, which allows you to view your stackup, including materials, dielectric layers, and technology layers (if present) which show the mapping of drawing layers to metal levels in the translated Sonnet project by clicking on the View Stackup button in the Substrate File Setup dialog box. For more information on the Stackup Viewer, please click on the? in the Stackup Viewer window. An example is shown below: 90

91 Chapter 3 Keysight ADS Interface Saving a Substrate File If you wish to save the Substrate File Settings for use in other designs that you will be simulating using Sonnet, you may do so in a.matl file. To do so, select Sonnet Setup Substrate Export from the menu of the Layout window. A browse window appears which allows you to save the present settings to a file. The default name is the design name with the.matl extension. You may use another name if you wish. Using an Existing Sonnet Substrate To use an existing Sonnet Substrate File for your design which you will be simulating using Sonnet, select Sonnet Setup Substrate Import from the menu of the Layout window. A browse window appears which allows you to select the desired.matl file. These settings are loaded into your design. For information on creating a Sonnet substrate file, see "Saving a Substrate File" on page 91. You may also use an existing Sonnet Substrate file or ADS Substrate by clicking on the buttons at the top of the Setup Substrate File window as shown below. The function of the buttons is shown in the table following. After every button entry is the equivalent menu command. Note, however, that clicking on a Load button will load the parameters from the source, but does not save the substrate information. Using any of the update commands, loads the parameters and saves them in a.matl file. ADS sources Sonnet sources 91

92 Keysight ADS Interface Button Load from Schematic Function Clicking on this button will import the substrate file being used by the ADS schematic. Menu Command: Sonnet Setup Substrate Update from Schematic Load from Momentum Clicking on this button will import the substrate file being used by the Momentum design. Menu Command: Sonnet Setup Substrate Update from Momentum Load from.slm Clicking on this button allows you to import an existing Momentum substrate file. Menu Command: Sonnet Setup Substrate Update from.slm Load from.matl Clicking on this button allows you to import an existing Sonnet substrate file. Menu Command: Sonnet Setup Substrate Import Load from Design Clicking on this button allows you to import a Sonnet substrate file from another design in your project. Menu Command: Sonnet Setup Substrate Update from Other Design Load from.son Clicking on this button allows you to import a Sonnet substrate file from another Sonnet project. Menu Command: Sonnet Setup Substrate Update from Sonnet.son file Viewing the Stackup You may open Sonnet s Stackup Viewer, which allows you to view your stackup, including materials, dielectric layers, and technology layers which show the mapping of drawing layers to Sonnet metal levels in the translated Sonnet project by clicking on the View Stackup button in the Substrate File Setup dialog box. You may also open the Stackup Viewer by selecting Sonnet Setup Substrate 92

93 Chapter 3 Keysight ADS Interface View Stackup from the main menu in the ADS Layout window. For more information on the Stackup Viewer, please click on the? in the Stackup Viewer window. An example is shown below: Defining the Box Once you have defined the substrate and the mapping, you need to specify the box used in Sonnet. Sonnet analyzes planar structures inside a six-sided metal shielding box. Port connections are usually made at the box sidewalls. The substrate is on the metal bottom of the box and represents the ground plane. Above the substrate are stacked the dielectric layers and metal levels. The side walls of the box are modeled as lossless metal. The top and bottom of the box may be assigned any metal type defined in the geometry project. 93

94 Keysight ADS Interface You use the Sonnet Analysis Box dialog box, shown below, to control these settings. You open the dialog box by selecting Sonnet Setup Analysis Box Edit from the menu in the interface. The first time you open this dialog box for a design, the box size is determined by the bounding box of the circuit elements translated to Sonnet and the default Margins set in the Preferences dialog box. You define the box and cell size in this dialog box in a very similar manner to how this is done in the Sonnet project editor. Sizes The entries in this section define the area of the box, and include Cell Size, Box Size and Num Cells. The Box Size remains fixed, but you may change either the Cell Size or the Number of Cells. You choose which you wish to change by selecting the Cell Size or Num Cells radio button. After changing one of the entries, click on the Calculate button or hit the Enter key to update the other factor. These three values are related in the following manner: Num Cells * Cell Size = Box Size 94

95 Chapter 3 Keysight ADS Interface where Num Cells must be an integer. Cell Size: This entry row defines the size of a single cell of the box area. The Sonnet electromagnetic analysis starts by automatically subdividing your circuit into small rectangular subsections. Em uses variable size subsections. Small subsections are used where needed and larger subsections are used where the analysis does not need small subsections. A Sonnet cell is the basic building block of all subsections, and each subsection is built from one or more cells. Thus the dimensions of a cell determine the minimum subsection size. You enter an X dimension (width) and a Y dimension (height). If you wish to change the cell size, click on the Cell Size radio button just above the entry boxes. Selecting cell size is important. The EM analysis automatically subsections the circuit based on the cell size. Small cells result in slower but more accurate analyses. For a detailed discussion of subsectioning, see Chapter 2 "Subsectioning" on page 21 of the Native Environment User s Guide. Box Size: Num Cells: This entry row displays the size of the box area. Initially, this box area is defined by the bounding box of the circuit elements being translated to Sonnet. The size is displayed in this dialog box but you may not directly edit the dimensions. If you need to increase the size of your box, use the margins to increase box size. For more details, see "Margins" on page 96. You may also specify a Sonnet custom box, for details, see "Sonnet Custom Box" on page 99. If you change the box size, the presently selected dimension, cells or num. of cells, stays the same and the other value is updated. This entry row defines the number of cells in the box area. You enter an X dimension (width) and a Y dimension (height). If you wish to change the number of cells, click on the Num Cells radio button just above the entry boxes. The number of cells must be an integer number in both dimensions. Note that the cell size is updated to the closest allowed cell size which allows for an integer number of cells to fit in the box area. Top Metal, Bottom Metal These drop lists allow you to select the metal type for the box top and box bottom. You can choose either a predefined metal type or user defined Sonnet material. You may not use a material that is defined using the thick metal model for a box top or bottom. For details on defining a new material and their parameters, see Sonnet Dielectrics, page

96 Keysight ADS Interface There are three predefined metal types available in Sonnet: Lossless, models a perfect conductor WG Load, models a perfect matched waveguide load. Free Space, which removes the top or bottom cover. WG Load is useful for modeling infinite arrays. The top or bottom cover is terminated with a perfectly matched waveguide load. Note this is not the same as an open environment. To model an open environment select Free Space, which sets the impedance of the cover to 377 ohms/sq, the impedance of free space. Note that the sidewalls are always modeled as perfect conductors. Margins This section of the dialog box may be used to increase the box size in Sonnet and to set the reference planes. Sonnet s em has an automatic de-embedding capability. When invoked, em removes the port discontinuity and a desired length of transmission line. The reference planes instruct em as to the desired length of the transmission line to be removed. One reference plane length per box side may be specified. Adding a margin moves the box wall out that distance from the bounding box for the circuit being translated. A feedline from the ADS port is added to the circuit and a reference plane is set for the length of the feedline if the port is defined as a box wall port. You may see the box in the Layout window while you are changing the margin if Show Box is selected. The outline appears in blue. Default Margins When you initially open the Analysis Box dialog box for a layout, the margins are set to the default value entered in the Sonnet Preferences dialog box (Sonnet Preferences). If you have changed the margins and wish to restore the default values, click on the Default Margins button in the Analysis Box dialog box. Changing the Margins To change the margins of your box, do the following: 96

97 Chapter 3 Keysight ADS Interface 1 If the Sonnet box is not presently visible, click on the Show Box button in the Sonnet Analysis Box dialog box to show an outline of the box in your layout view. The boundaries of the box appears as a blue line in your layout view. If all the margins are set to zero, the box outline coincides with the bounding box of the ADS layout as shown below. Note that some of the colors in the ADS pictures have been changed to provide more clarity in this documentation. 2 Enter a value of 25 in each of the Margin text entry boxes. The Analysis Box dialog box should appear similar to the illustration below The outline of the box in the layout has not changed because the margin values entered have not yet been applied to the layout. Length Units Margins Calculate button 97

98 Keysight ADS Interface 3 Click on the Calculate button or the Enter key to update the layout view. This will move the box wall 25 mils on the right, left, top and bottom wall. Since mils are presently the length unit, a value of 25 causes the box wall to move 25 mils. Notice that the box outline in the layout view has moved 25 mils in each direction. Shown below is the same circuit translated into Sonnet s project editor. Notice that the reference planes are 25 mils long and the feedline was automatically added when the margins were enlarged. Reference Planes Displaying the Box NOTE: Displaying the box or creating a custom box will change the date on the layout view and it will become out of sync with Sonnet. You must save the layout and translate the layout in order to sync up the two views. If you wish an outline of the analysis box to appear in your layout, click on the Show Box button in the Analysis Box dialog box. The outline appears in blue. Note that this button is only enabled when you are NOT using a custom box. To remove the box outline from your layout view, click on the Hide Box button. 98

99 Chapter 3 Keysight ADS Interface Sonnet Custom Box If you wish to set a specific box size in order to make the Sonnet Box bigger than the bounding box without having to use the margin settings, you can use a Sonnet Custom Box. Creating a Custom Box To create a custom box, do the following: Open the design layout and select Sonnet Setup Analysis Box Create Custom Sonnet Box in the main menu. A question about using a custom box appears on your display. 4 Click Yes to close the question box. The cross-hair cursor appears in your layout window. 5 Click in the layout on one corner of the desired custom box. 6 Drag the cursor to the desired box size. A rubber-band will follow your cursor showing you the box size. 7 When you have the desired box size, click in the window again. The outline of the custom box appears in your layout. A green outline indicates a custom box. Turning a Custom Box on and off If you have added a Sonnet custom box to your circuit, but do not wish to use it for a simulation, you can switch back to your default box size by clicking on the Delete Custom Box button at the bottom of the Analysis Box dialog box. If you want to use the Custom Box again, click on the Set Custom Box button. The previously entered custom box will appear in your layout in green. 99

100 Keysight ADS Interface Changing a Custom Box To change the size of a custom box after it has been defined, you delete the existing custom box, then add a new one. 1 Select Sonnet Setup Analysis Box Delete Custom Sonnet Box from the layout menu. A question about using a custom box appears on your display. 2 Click Yes to close the question box. The custom box no longer appears in your layout. 3 Open the design layout and select Sonnet Setup Analysis Box Create Custom Sonnet Box from the layout menu and follow the directions for adding a Sonnet Custom box. Viewing the Box If you wish to center the box in your layout, click on the View All button in the Analysis Box dialog box. Estimating Sonnet Processing Time Knowing the amount of memory needed to analyze a circuit and the subsectioning will help you to estimate the processing time for your simulation. Your ability to predict this will improve with experience. Clicking on the Estimate Memory button in the Analysis Box dialog box opens the Estimate Memory dialog box and translates and subsections your project. A simple status popup appears to indicate that the circuit is being subsectioned. When the subsectioning is complete, the memory use estimate and the subsectioning information, listed by level and total amounts, appears in the dialog box. You may click on the View Subsections button to open a viewer which displays the subsectioning of your circuit. You may view all metalization levels and their subsectioning. 100

101 Chapter 3 Keysight ADS Interface TIP You may also use the command Sonnet Analysis Estimate Memory from the main menu of the layout window to obtain an estimate of the memory required to analyze your circuit. Ports Once you have defined the substrate and analysis box, you need to specify the parameters for the ports to be used in Sonnet and the use of reference planes. ADS ports are converted to Sonnet ports. Ports can be converted to standard box-wall ports, co-calibrated ports, auto-grounded ports, via ports and internal ports in Sonnet. Diagonal ports in ADS are supported but by default are converted to cocalibrated ports. The type of Sonnet port to which the ADS port is converted is based on the layer the port is on and its placement in the circuit. For more information on Sonnet ports, see Chapter 4 "Ports" on page 65 in the Native Environment User s Guide. 101

102 Keysight ADS Interface You use the Sonnet Ports dialog box, shown below, to control these settings. You open the dialog box by selecting Sonnet Setup Ports from the menu in the interface. This dialog box lists all the ports in your ADS layout and the Sonnet parameters to be used to represent them. To change the port parameters, select the port in the list on the left, then enter the desired parameters in the right side of the dialog box, shown below. Once you have finished entering the desired parameters, click on the Update button to apply the changes. The list of ports on the left side of the dialog box is updated. If you wish to print a summary, click on the Summary 102

103 Chapter 3 Keysight ADS Interface button. The entries in the Edit Port section of the dialog box changes depending on the type of Sonnet port that is selected in the Type drop list as shown below. Entries in the Edit Port section of the dialog box are described below. Boxwall Port Co-Calibrated Port ADS Port #: This is the ADS Port # assigned in ADS. You may not edit this value, it is shown here to identify which port you are editing. To change the number of the port, you must edit the layout in ADS. Name: This is the name of the pin in the ADS layout. You may not change the name here. To change the name of the port, you must edit the layout in ADS. Son Port #: This is the port number of the Sonnet port which corresponds with the ADS port identified above. You may enter any port number as long as it is an integer value. For example, you can have port 1 and port -1 in your circuit which in Sonnet would create a push-pull port. You may also use the number zero to identify a port used for a ground connection.for more detailed information about port numbering in the Accurate solver, please see "Special Port Numbering" on page 69 of the Native Environment User s Guide. Type: This field identifies the type of Sonnet port which will be used in your EM simulation. If the ADS port is on the box wall, then it is converted to a Sonnet box wall port. If the ADS port is located inside the analysis box, the position and layer of the ADS port are analyzed and an appropriate Sonnet port is used. In all cases though, the drop list is enabled and you may choose a Box-wall port, Internal port, 103

104 Keysight ADS Interface Autogrounded port, or Co-Calibrated port. In the case of a probe port, the ADS port is converted to a via-port which extends from the present level to GND. For a detailed discussion of Sonnet port types, see Chapter 4 "Ports" on page 65 in the Native Environment User s Guide. Add Ref. Plane: If you wish to extend a reference plane from the equivalent box wall port, enter the length of the reference plane here. Sonnet s em has an automatic de-embedding capability. When invoked, em removes the port discontinuity and a desired length of transmission line. The reference planes instruct em as to the desired length of the transmission line to be removed. One reference plane length per box side may be specified. This field appears for a Box wall or Internal port. If the port type is Internal, these fields may not be changed. Total Ref. Plane: This entry displays the total length of the reference plane. If you are using a standard box, this value is the margin plus any additional length entered in the Add. Ref Plane text entry box. You may not edit this value; to change it you must change your analysis box setup. This field appears for a Box wall or Internal port. If the port type is Internal, these fields may not be changed. Cal. Length: This entry is the calibration length you wish to use with the Cocalibrated or Autogrounded port and corresponds to the same field in the Port Properties dialog box (Modify Port Properties) in Sonnet s project editor. For a detailed discussion of calibration lengths, please "Rules for Reference Planes" on page 103 of the Native Environment User s Guide. Ref. Plane: This entry is the reference plane length you wish to use with the Cocalibrated or Autogrounded port and corresponds to the same field in the Port Properties dialog box (Modify Port Properties) in Sonnet s project editor. For a detailed discussion of reference planes, please see "Rules for Reference Planes" on page 103 of the Native Environment User s Guide. Port Impedance: Enter the four impedance values in the text entry boxes: Resistance (in ohms), Reactance (in ohms), Inductance (in nanohenries), and Capacitance (in picofarads). Shown below is the circuit equivalent of a Sonnet port using the impedance values. The default values for a port are R= 50 ohms and all other impedance values are zero. R + jx L C V 104

105 Chapter 3 Keysight ADS Interface If while editing a port s parameters, you wish to delete any changes you ve made so far, click on the Load from Layout button. This loads in the port settings from the layout which essentially acts as a Revert to Saved command for the Sonnet Ports dialog box. When you click on OK to close the Edit Port dialog box, the entries in the Sonnet Ports dialog box are updated to reflect any changes that you made. Sonnet s Component Feature You may use all Component types from Sonnet in the interface, but if you wish to connect your ADS Models inside the ADS environment with your Sonnet simulated results, we would recommend using the Ports Only type of Component. For a detailed discussion of Components as used in Sonnet, please refer to Chapter 6 "Components" on page 131 in the Native Environment User s Guide. 105

106 Keysight ADS Interface Options The Options dialog box, shown below, allows you to choose your simulation program, control your subsectioning options, control your adaptive sweep settings, set analysis run options, control your translations options, choose what type of model you wish to calculate, and control the creation of datasets. Select Sonnet Setup Options All Options to open the dialog box. Simulation Program Project Options Translation Options Subsectioning Options Model Options Adaptive Sweep Settings Dataset Options The following sections explain each section of the Options dialog box. Simulation Program Sonnet allows a user to run simulations on their own computer using a local copy of Accurate solver, or to submit the job to an solver running on another computer (Remote em). You can use settings in the Options dialog box to determine which processor runs the analysis. 106

107 Chapter 3 Keysight ADS Interface Auto Detect Program: Selecting this option allows the software to determine the processor settings for Sonnet on your computer and submit the job to your default processing choice. If you wish to specify the processor, clear this checkbox. Local em: Selecting this option runs your simulation on a locally installed copy of the solver. Note that if a local copy is not available, this option is disabled. If you wish to have a progress bar displayed during the simulation, select the Progress Bar checkbox. RemoteEm/Cluster: Selecting this option runs your simulation on a remotely installed copy of the solver. To configure a remote server, click on the Configure button to open Sonnet s analysis monitor in which you can configure a Remote em processor. For more information on configuring and using Remote em, please refer to the Remote em Computing manual. Subsectioning This section of the Options dialog box allows you to control your subsectioning. You control your subsectioning through use of the Analysis Speed/Memory Control. The three options are detailed below: Default Metal Fill Type Analysis Speed/ Memory Control Default Via Fill Type Advanced Subsectioning button Default Metal Fill Type: This field allows you to set the default fill type for metal polygons in the translated project. Choose from Staircase, Diagonal or Conformal. For more information on fill types in Sonnet, please see Default Subsectioning of a Polygon, page 29 in the Native Environment User s Guide. Default Via Fill Type: This field allows you to set the default fill method for vias in your translated project. Choose from Full, Ring, Vertices or Center. For more information on via fill methods, please see "Meshing Fill for Vias" on page 284 of the Native Environment User s Guide. 107

108 Keysight ADS Interface Fine/Edge Meshing: Em uses the XMIN and YMIN settings of each individual polygon, and the edge meshing settings of each individual polygon. This is the default setting. It uses the most memory and returns the most accurate answer. Coarse/Edge Meshing: Em checks the XMin value of each individual polygon. If the value is less than 50, em uses 50. Otherwise, em uses the XMin value of that polygon. Same for YMin. Em uses the edge meshing settings of each individual polygon. Coarse/No Edge Meshing: XMin and YMin are treated the same as cited for the option above, but em disables edge meshing for all polygons. This setting uses the least amount of memory and runs the fastest but at the cost of some accuracy. Advanced Subsectioning Options Clicking on the Advanced button in the Subsectioning Options section of the Sonnet window (as shown above) opens the Sonnet Advanced Subsectioning Options, as pictured below. You may also access this dialog box by selecting Sonnet Setup Options Advanced Subsectioning Options. This dialog box allows you to control several subsectioning options as well as the subsectioning frequency. The options are discussed below: 108

109 Chapter 3 Keysight ADS Interface Since subsectioning has a direct effect on processing time and accuracy, this allows the experienced user a measure of control over the trade off between them.! WARNING Be aware that these are advanced options and should not be changed from their default values except by an experienced user who understands the effects of these options. Maximum Subsection Size: Sonnet s Accurate solver, em, uses a variable subsection size. Small subsections are used where needed, such as around corners, and larger subsections are used elsewhere. This reduces the size of the matrix which must be inverted, often providing a dramatic increase in the speed of an analysis. In no case are the subsections smaller than a single cell. This field allows you to limit the maximum size of the subsection, generated by the Accurate solver, in terms of subsections per wavelength. The default of 20, used when this option is not on, is fine for most work and means that the maximum size of a subsection is 18 degrees at the highest frequency of analysis. Increasing this number decreases the maximum subsection size until the limit of 1 subsection = 1 cell is reached. Estimated Epsilon Effective: Normally, em has an algorithm which estimates the effective dielectric constant used to determine the wavelength used for maximum subsection size. If this option is selected you may override the automatic algorithm and force em to use your dielectric constant to calculate the wavelength which is used in setting the Maximum Subsection size. If this option is not on, Auto appears in the text entry box to indicate that em is using its algorithm to determine the subsectioning frequency. Polygon Edge Checking: Normally em considers one adjacent metal level in either direction from the present level when computing the subsectioning. This is an important consideration when thin dielectric layers are used. Polygon Edge Checking allows you to override the automatic algorithm and specify how many adjacent levels should be considered when calculating subsections. This entry should be an integer value. Note that entering a value of zero causes em to only look at the present metal level. You select the type of edge checking you wish to use, Level or Technology Layer, from the drop list which is enabled when you select this checkbox. Note that entering a value of zero causes em to only look at the present metal level. 109

110 Keysight ADS Interface If you select level, then the number of levels you enter are checked in either direction. For example, as shown below, if polygon edge checking is set to 2, then using level 6 as the reference level, levels 6-4 would interact in the upward direction and levels 6-8 in the downward direction. Polygon Edge Checking Metal Levels - Number of Levels=2 Metal Levels 6-4 Interact Reference Level Metal Levels 6-8 Interact If you select Tech. Layers, then the number of adjacent Technology Layers you enter is checked in either direction. Metal levels which do not use Technology Layers are not included in the count but if a metal level is in between levels with Technology Layers, then polygon edge checking is done on that metal level as well. For example, as shown below, polygon edge checking is set to 2. Using Level 6 as the reference level, Technology Layer C and Technology Layer A (metal levels 6-1) interact and Technology Layer C and Technology Layer E (metal levels 6-9) interact. Polygon Edge Checking Technology Layers - Number of Tech Layers =2 Metal Levels 6-1 Interact Reference Level Metal Levels 6-9 Interact 110

111 Chapter 3 Keysight ADS Interface Auto Height Vias:Normally vias extend from the specified starting metal level to the specified ending metal level. If the auto height vias option is selected, then a via will terminate if its path, starting from the upper metal level and extending downward, contacts planar metal. For example, if you define a via from metal level 3 to metal level 0 and there is a planar polygon in its path on level 2, then the via is terminated on level 2 and therefore extends from level 0 to level 2. Note that the via is depicted in both the 2D and 3D view as the actual metal which will be analyzed. However, the associated Via Technology Layer still appears unchanged in the stackup since other vias associated with the Technology Layer may still extend the fully defined length as shown below. Only polygons which completely cover the cross sectional area of the via are guarenteed to affect the height of the via. Note that planar metal that is on an intervening metal level but does not intersect the path of the via does not affect the height of the via. Choose Subsection Frequency based on: The Accurate solver, em, uses the subsectioning frequency to calculate the wavelength which is used in setting the Maximum subsection size. The subsectioning frequency is determined by the radio buttons described below: Present and Previous Analyses: This is the default setting for the subsectioning frequency. Select this option if you wish to analyze your project at the highest frequency used in this or any previous run of the project. Present Analysis Only: In this case, the highest frequency at which the project is analyzed for this run is used to subsection the circuit. Previous Analyses Only: Select this option if you wish to analyze your project in a different frequency range than a previous run but 111

112 Keysight ADS Interface wish to use the same subsectioning on your circuit. The maximum frequency from all previous runs on this project will be used as the subsectioning frequency. Use Fixed Frequency: Select this option to enter the frequency you wish to use for the subsectioning frequency. Enter the desired frequency in the text entry box to the right which is enabled when this option is selected. This frequency will be used as the subsectioning frequency for all analyses of this project. All Polygon Meshing (ADS to Sonnet) XMin, XMax, YMin, YMax: Sonnet allows you to control how cells are combined into subsections for each polygon. This is done using the parameters X min, Y min, X max and Y max. These fields are applied as a global setting for all polygons. For a detailed discussion of these parameters and how they affect subsectioning in Sonnet, please refer to "Changing the Subsectioning of a Polygon" on page 29 of the Native Environment User s Guide. Use Edge Mesh: When using the Edge Mesh option, all Manhattan polygons (no diagonal edges) are treated as if they were non-manhattan polygons. In other words, the edge subsections are always one cell wide regardless of X Min or Y Min. This field is applied as a global setting for all polygons.when used in conjunction with large X Min or Y Min values, this option can be very useful in reducing the number of subsections but still maintaining the edge singularity. This is very often a good compromise between accuracy and speed. Conformal Mesh Subsection Length: You may set a maximum length for a conformal section by selecting this checkbox and entering the desired length in the text entry box below. This is useful in reducing the size of your conformal sections to ensure higher accuracy. The default length of a conformal section is 1/20 of the wavelength of the subsectioning frequency. All Metal Fill Type: This field allows you to set the fill type for all metal polygons in the translated project. If you do not wish to set a global fill type, select <off> from the drop list. If you wish to set a fill type, choose from Staircase, Diagonal or Conformal. For more information on fill types in Sonnet, please see Default Subsectioning of a Polygon, page 29 in the Native Environment User s Guide. All Via Fill: This field allows you to set the fill method for all vias in your translated project. If you do not wish to set a global fill method, select <off> from the drop list. If you wish to set a fill method, choose from Full, Ring, Vertices or Center. For more information on via fill methods, please see "Meshing Fill for Vias" on page 284 of the Native Environment User s Guide. 112

113 Chapter 3 Keysight ADS Interface Adaptive Sweep Settings You can set up an adaptive sweep for your analysis in the Frequency Plan dialog box (for more information see "Analysis Frequencies" on page 123). One of the frequency sweeps you may chose for your simulation is an Adaptive Band Sweep (ABS). There are advanced options available to control Adaptive Sweeps in the Sonnet Advanced ABS Options dialog box which you open by clicking on the Advanced button in the Adaptive Sweep Settings section of the Options dialog box. You may also open this dialog box by selecting Sonnet Setup Options Advanced Subsectioning Options. Advanced button Advanced ABS Settings The Sonnet Advanced Options dialog box, pictured below, allows you to control the ABS Caching Level and the ABS Frequency Resolution. The controls are explained below. ABS Caching Level: The ABS caching level determines if and how much of the ABS caching data is stored in your project. The levels are detailed below. None: Select this option if you do not wish to store any ABS cache data in your project. If this option is selected and you stop an ABS analysis before completion, the only data available is the data calculated for the discrete data points. When you resubmit the ABS job, the cache data will need to be recalculated. Thus, the analysis must start all over again. 113

114 Keysight ADS Interface Stop/Restart: Select this option to store the ABS cache data while an ABS analysis is running. This allows you to stop an ABS analysis and restart it at a later time without losing the data from the processing done before the stop. This option deletes the cache data when convergence is reached and the ABS analysis is completed. This is the default setting. Multi-Sweep plus Stop/Restart: Selecting this cache level saves the ABS cache data for every analysis performed on the project. This saves you processing time on any subsequent ABS analyses but be aware that the cache data will be calculated for any analysis of the project including non-abs types of analysis, increasing the project size. This option should be used when you think you might want to re-analyze the project, using different ABS ranges or settings. It is important when using this option that all your analyses use the same subsectioning frequency. This ensures that any pre-existing ABS cache data can be used in the present analysis The default setting used to determine the subsectioning frequency is to use the highest frequency from the present analysis job. If you perform multiple sweeps over different frequency bands then the cache data from one run will be invalid for the next, since the subsectioning frequency would be different. In order to avoid this you should use the controls for the subsectioning frequency found in Sonnet s Advanced Subsectioning dialog box to ensure that the same frequency is used for all analyses. For more details about setting the subsectioning frequency, please see "Advanced Subsectioning Options" on page 108. ABS Frequency Resolution per Sweep: The resolution provides the minimum value of the gap between data points in an ABS sweep. This can be calculated automatically by em or input by the user. Automatic: The resolution of the frequency band used in an ABS analysis is determined by the Accurate solver, em. This is the default setting. The automatic setting provides approximately 300 frequency points in the band. Manual: If you wish to set the resolution for an ABS analysis, select this radio button and enter the desired resolution in the adjacent text entry box. The units for this value are the presently selected frequency units for the project. There are several things to be aware of when using the manual setting for the ABS resolution. Coarse resolution does not speed things up. Once a rational polynomial is found to ''fit'' the solution, calculating the adaptive data uses very little processing time. A really coarse resolution could produce bad results by not allowing the ABS algorithm to analyze at the needed discrete frequencies. Fine resolution does not slow down the analysis unless the number of frequency points in the band is above approximately points. A step size resulting in at least 50 points and less than 2000 points is recommended. 114

115 Chapter 3 Keysight ADS Interface Enhanced Resonance Detection: This feature is useful when the circuit response includes one or more extremely narrowband resonances as is typical for superconductor applications. When enabled, ABS searches for and resolves such resonances in detail by adding adaptive frequencies with very fine resolution in the vicinity of each resonance. ABS then performs a full-wave discrete simulation at each detected resonance to obtain the highest level of accuracy possible in terms of magnitude and frequency. Project Options This section of the Options dialog box allows you to select the Compute Currents and Q-Factor accuracy run options and access the Advanced Run Options dialog box. Computing Current Density Select the Compute Currents checkbox in the Options dialog box to compute current density data during your analysis. This run option outputs current density information for the entire circuit which can be viewed using Sonnet s Current Density Viewer. Be aware that for an adaptive sweep, current density data is only calculated for discrete data points and this option is not available for a DC Point sweep. For instructions on how to open the current density viewer, see "Current Density Viewer" on page 136. Q-Factor Accuracy When performing an ABS sweep, there is an option to increase the accuracy of the Q-Factor. The Q-Factor is the quality factor of the project and is calculated using this formula: Q Factor = imagy nn ( realy nn ) Selecting this option increases the accuracy of the Q-factor when ABS is used. Normally ABS uses S-parameters to determine convergence. When this option is used, ABS uses both the S-parameters and Q-factor for convergence criteria. This option should be used whenever you plan on viewing/calculating Q-factor, but could require more discrete frequencies. 115

116 Keysight ADS Interface Advanced Project Options There are a number of advanced run options available in the Sonnet Advanced Project Options dialog box. This dialog box is accessed by selecting the Advanced button in the Project Options section of the Options dialog box. You may also open this dialog box by selecting Sonnet Setup Options Advanced Project Options. The Sonnet Advanced Project Options dialog box allows you to select additional run options. By default, the De-Embed option is on, and all other options are off. To turn on an option, click on the appropriate checkbox. For information on any of the available options, please refer to Sonnet s help which may be accessed by selecting Help Sonnet Help from any Sonnet application menu. You may locate the desired information by searching in the index under the run option name. Comments If you wish to add any notes or comments to your design, you may enter them in the Sonnet Project Comments entry box. The comments are saved in your project by the Keysight ADS Interface. Translation Options (ADS to Sonnet) You are able to control how many of the circuit elements are translated when moving from the ADS environment and creating a Sonnet project. 116

117 Chapter 3 Keysight ADS Interface There are two options available in the Options dialog box: Simplify Single Vias and Simplify Array Vias. Convert Single Vias:This option places a bounding box on vias being imported and creates a rectangular via the size of the bounding box in place of the imported via. Simplify Via Arrays: This option locates via arrays and perform simplification to create one equivalent via in Sonnet to represent the via array in order to increase analysis efficiency by reducing the memory and processing requirements for the circuit. This feature automatically performs this simplification during the translation process using controls set by the user. For a detailed discussion of Via Array Simplification, please see Appendix I "Via Simplification" on page 165. The options which control simplification are available in the advanced translation options. Identify Bar Vias: This option is enabled when the Simplify Via Arrays option is enabled. This option will identify bar vias when the L/W ratio requirement is met. Each via identified as a bar via will have its via fill type set to Bar via fill type during translation. Enter the desired minimum length to width ratio a via polygon must possess to be considered a bar via. The default value is 2.5. For a detailed discussion of Bar Via Simplification, please see Appendix I "Via Simplification" on page

118 Keysight ADS Interface Advanced Translation Options To access the advanced translation options, click on the Advanced button in the Options dialog box. You may also access this dialog box by selecting Sonnet Setup Options Advanced Translation Options. Please note that the options in this dialog box are global settings which will override all other settings; hence, these options should only be used by an experienced user. The various options are detailed below: Process Stackup and Geometry Options All Thick Metal: Converts all metals which use a conductivity and thickness setting in your EM structure to the Thick Metal metal type in the destination Sonnet project. Thin film resistors are not converted. For more information about Sonnet s metal types, please refer to "Creating Planar Metal Types" on page 44 of the Native Environment User s Guide. All Lossless Metal: Converts all metal in your EM structure to the Lossless metal type in the destination Sonnet project. For more information about Sonnet s metal types, please refer to "Creating Planar Metal Types" on page 44 of the Native Environment User s Guide. All Lossless Dielectrics: Converts all dielectrics in your EM structure into lossless dielectrics in the destination Sonnet project. For more information on Sonnet s modeling of dielectric loss, please refer to "Dielectric Layer Loss" on page 60 of the Native Environment User s Guide. 118

119 Chapter 3 Keysight ADS Interface Remove Unused Materials: Removes any defined materials such as planar metal types, via metal types or dielectrics that are not used in the translated Sonnet project. The only materials defined in the resulting Sonnet project are materials used in the Sonnet project. Selected by default. If this option is turned off, all materials defined in the ADS layout are translated. Mom. Thick Metal Expansion: When thick metal is modeled in Momentum, an extra dielectric is put into the stackup to generate the new dielectric into which the thick metal will extend. The height of this new dielectric is the same height as the thickness of the metal. This option is selected by default so that when the translation is performed, Sonnet behaves in the same manner as Momentum and adds an extra dielectric layer to the Sonnet project. If this option is cleared, then Sonnet does not add this extra layer during the translation. Mom. Keep Free Space:When converting from a Momentum substrate to a Sonnet substrate file, the top of the Sonnet box will be set to Free Space, instead of lossless metal. The Free Space setting removes the box top. Union Geometry: Merges any adjacent metal polygons with the same metal properties. If a polygon has another geometry element attached, such as a port, it will not be merged. This option is probably best used for the flow of a layout that has been generated from a schematic with MLIN, MCURVE, etc. Add Via Pads: Adds a Fill metal pad to the top and bottom of any via which does not already have a pad at the bottom or top in the geometry being input. The pad is created using the same metal type as the via. Note that the via pad is added by the Sonnet Accurate solver prior to analyzing and is not shown in the Sonnet s project editor 2D view. It is, however, visible in the 3D view in the project editor. Lossless Extensions: Transmission lines are added in your translated Sonnet project which extend from the box wall to your circuit. If this option is selected, Lossless metal is used for the extensions. If this option is not selected, the extensions inherit their metal properties from the polygon to which the ports are attached. Model Vias as Solid: Via metal types are created in the Sonnet project to model via polygons. The loss model used for these via metal types is the Volume loss model for which you can choose to model your vias as hollow or solid. Selecting this check box will model all of your vias as solid. For more information on the Volume Loss model and the solid setting, please refer to "Volume Loss Model" on page 53 of the Native Environment User s Guide. 119

120 Keysight ADS Interface Via Array Translation Options This section of the dialog box contains the options which control how the via array simplification is performed when a circuit is translated into Sonnet. For a detailed discussion of these controls, please refer to Simplify Via Array Options, page 166. Model Options This section of the Options dialog box allows you to select the type of model you wish to produce, whether you wish to create a dataset, and the Advanced Model options. You select the type of model you wish to produce when you run your Sonnet EM analysis. There is only one model type available at this time, the Touchstone S- Parameter Model. S-Parameter Model Selecting the S-Parameter Model instructs the solver to produce an optional output file of S-parameters in the Touchstone format. The file has the extension.snp where n is the number of ports. The S-parameter file is placed in your ADS design along with a schematic view and layout view of the model and a model symbol. When you open the model schematic for viewing, the file information is displayed. For details on viewing your model, see "Using the Models" on page 141. You may elect to save the Y or Z-parameter data also, see the Advanced Model options below. 120

121 Chapter 3 Keysight ADS Interface Advanced Model Options Clicking on the Advanced button opens the Advanced Model Options dialog box which allows you to determine what is included with the model created by the simulation. You may also access this dialog box by selecting Sonnet Setup Options Advanced Model Options. Model Symbol You may specify the type of symbol you wish to use for the model: layout lookalike or black box. A layout look-alike uses a small graphic of your layout as the component symbol. The black box uses a small box with the I/O connections. Both types of symbol display the model name. Both types are shown below. Note that some color changes have been done for clarity. Layout look-alike Black Box If you select the layout look-alike as your symbol type, then the controls below, which control the size and appearance of your layout, are enabled. You define the size in terms of a schematic unit. You may use either a layout unit or the minimum pin distance as the size and then enter the equivalent in schematic units. If you 121

122 Keysight ADS Interface wish to add a ground reference to your symbol, select the Add Ref. Pin checkbox. If you wish to display the pin labels shown in the design from which this model was generated, select the Add Pin Text checkbox. The Sonnet project is re-imported into ADS. This allows you to update your design in ADS. Your layout view will appear similar to the geometry in your Sonnet project. If the project displayed in the text entry block below is not the one you wish to use, then click on the browse button to select another. Touchstone S-Parameters Options This section of the Advanced Model options dialog box allows you to select the type of data you wish to include in your optional output file. High Precision: Clicking on this checkbox outputs high precision (16 figures) data for the response file. Include Adaptive Data: Clicking on this checkbox includes all the discrete and adaptive data from an ABS analysis. If you wish to only export the discrete data points, disable this checkbox. The checkbox is set by default. Data Type: You select De-embedded or Non-De-embedded from this drop list. Each port in a circuit analyzed by Sonnet s Accurate solver, em, introduces a discontinuity into the analysis results. In addition, any transmission lines that might be present introduce phase shift, and possibly, impedance mismatch and loss. Depending upon the nature of your analysis, this may or may not be desirable. De-embedding is the process by which the port discontinuity and transmission line effects are removed from the analysis results. For more details about de-embedding, please see Chapter 5 "De-embedding" on page 97 in the Native Environment User s Guide. Parameter: Select which type of parameter: S-, Y- or Z-parameter you wish to output from the drop list. Complex: The response is a complex number composed of two parts. You may select what those two parts represent by selecting a choice from the drop list. The choices are:. DB - Angle Magnitude - Angle Real - Imaginary 122

123 Chapter 3 Keysight ADS Interface Create Dataset Select this checkbox if you wish to create a dataset for your model that may be displayed in the Data Display window in ADS. Once the Sonnet analysis is complete, the dataset will be created and opened in the Data Display window in ADS. This will allow you to compare the Sonnet data to response data obtained from another source. You may also create a dataset from the Sonnet menu in your layout window by using the Sonnet Datasets Create Dataset command. For more details on datasets, see "Viewing the Results in ADS" on page 139. Analysis Frequencies You are able to set up multiple frequency sweeps for your Sonnet analysis using the Frequency Plan dialog box. Select Sonnet Setup Frequencies from the main menu of the layout window to access this dialog box. Each frequency range (sweep) that you add is displayed in the Sonnet Frequencies list in the interface. If 123

124 Keysight ADS Interface you wish to print out the list of analysis frequencies, click on the Summary button to open a new window with all the frequency sweep information and click on the Print button. Units Frequencies List Sweep Entry/Edit Adding/Editing Frequency Sweeps You add new analysis frequencies by setting up a sweep in the right hand side of the dialog box, then clicking on the Add button. The new sweep appears in the Frequencies List to the left. Enabled: This checkbox determines whether this frequency range is used in the Sonnet analysis. When the frequency range is enabled, the simulation includes the frequency points defined here. If the range is disabled, then the range still appears in the list but is not used as an analysis control for the Sonnet simulation. The list of frequency ranges indicates if a particular range is enabled or not. Sweep Type drop list: You select the type of frequency sweep you desire from this drop list. The choices include Adaptive Sweep (ABS), DC Point, Linear Sweep, Single Frequency, Exponential Sweep, and Linear Sweep (# points). The entry boxes below the drop list are updated to correspond to whichever type of sweep is selected. The sweep types and their parameters are explained below. 124

125 Chapter 3 Keysight ADS Interface Adaptive Sweep (ABS) An Adaptive Sweep uses the Adaptive Band Synthesis (ABS) technique to perform a fine resolution analysis of a specified frequency band. You enter the desired frequency band by entering the beginning frequency in the Start text entry box and the ending frequency in the Stop text entry box. Em analyzes the circuit at the beginning and end frequencies. Using an iterative process, em then analyzes at other discrete frequencies and determines a rational polynomial fit to the S- parameter data within the frequency band. Once a rational polynomial fit is achieved with an acceptable error, the frequency response across the specified bandwidth is calculated. The output data consists of the discrete data points, frequencies at which the Accurate solver, em, performs an electromagnetic analysis, and the adaptive data, which is data calculated using the rational polynomial. Please note that when the value of the S-parameters is close to 1 (0 db) over the entire band you may have small ripples or oscillations in the S-parameter values. This is due to the rational fitting model having too many degrees of freedom when trying to fit a straight line. If this is a problem, it is recommended that you analyze the frequency band in which this occurs with another type of sweep. If you only input a Start frequency or if the Start and Stop frequency are the same value, em will perform an analysis at that discrete point. If you enter a value of zero as the starting frequency for an ABS sweep, the data for a DC Point is automatically calculated. Once the ABS sweep is complete and has produced the adaptive data, em extrapolates the adaptive data to DC. For a detailed discussion of Adaptive Band Synthesis, see Chapter 7 "Adaptive Band Synthesis (ABS)" on page 149 in the Native Environment User s Guide. DCPoint The DCPoint sweep analyzes your circuit at a low, non-zero frequency to supply response data at a DC point. This type of response data is necessary for some circuit analysis tools. You can choose to have the DC analysis frequency calculated automatically by em (default) or enter a frequency manually. The low, non-zero frequency must be chosen carefully. If the frequency is too high, then the analysis is done at a point where the response of the circuit is already changing. If the frequency is too low, then precision errors occur which produce faulty data. An algorithm is provided with your software to automatically calculate this frequency which has a 95% success rate. As mentioned above, analyzing at such a low frequency may lead to precision errors which corrupt the output data, so results of this analysis option should be scrutinized carefully. 125

126 Keysight ADS Interface You may not calculate current density data when using this type of sweep. Linear Sweep A Linear Sweep is used to execute an analysis using only one or multiple frequencies evenly spaced in an ascending order. Enter the Start, Stop and Step values in the appropriate text entry boxes. If you wish to analyze at only one frequency, enter that frequency in the Start text entry box. Otherwise, Start provides the beginning frequency, Stop the ending frequency and Step the spacing. For instance if the Frequency Units were set to GHz, then the values of 2, 10, 2 would start an analysis at 2 GHz and end at 10 GHz with steps of 2 GHz (e.g., 2, 4, 6, 8 and 10 GHz). If you omit the step value in a linear sweep, the circuit is analyzed at two frequencies, the start and stop values. Single Frequency Exponential Sweep Linear Sweep (# points) Single Frequency analyzes your circuit at only one frequency entered in the Start text entry box. An Exponential Sweep specifies an exponential frequency sweep from the starting frequency to the end frequency with a common ratio between the desired number of frequency points. The text entry boxes are Start, Stop and # of Points. The # of Points is the number of frequency points used for the analysis. A Linear Sweep (# points) uses only one or multiple frequencies evenly spaced in an ascending order. You specify the starting frequency and the ending frequency by editing the Start, and Stop text entry boxes, respectively. The frequency range is divided by the number of points to provide a constant interval between analysis frequencies. When you have completed entering the parameters for the type of sweep you have chosen, click on the OK button to apply the changes and close the dialog box. Editing a Frequency Type If you need to modify a frequency type, click on it in the list to select it, then edit the parameters which appear in the Sweep Entry/Edit section of the dialog box. When you have completed making the desired changes, click on the Update button. The entry in the list is updated with the new information. 126

127 Chapter 3 Keysight ADS Interface Deleting a Frequency Type To delete a frequency type, click on its entry in the Frequencies List to select it, then click on the Delete button. If you wish to delete all existing frequency entries, click on the Clear All button. Loading Frequency Sweeps If you have set up analysis frequencies in your ADS design, you may import them from the schematic of your design by clicking on the Load from Schematic button or from Momentum by clicking on the Load from Momentum button. If the Append to List checkbox is not set, then the imported frequencies will replace all those presently in the list. If the Append checkbox is selected, the imported sweeps will be added to the end of the list. If you have created an external frequency file in Sonnet (.eff) you may import it by clicking on the Load.eff file button. For details on the syntax of the External Frequency File, please see Help in Sonnet by searching for External Frequency File in the Index. Connectivity Checker Once you have completed the setup of your Sonnet simulation environment, but before you run your analysis, you may wish to check your circuit to ensure that no opens or shorts are created during the translation. You may do so by invoking Sonnet s Connectivity Checker from the Keysight ADS Interface. Select Sonnet Tools Check Connectivity from the main menu of the interface. Your layout is translated and the Sonnet project editor is opened with the Connectivity Checker turned on. For details on using the Connectivity Checker, please see "Creating the Models and Model Views" on page 17 of the Blink User s Guide. 127

128 Keysight ADS Interface States and Properties of the Interface Saving a State Once you have completed the setup of your Sonnet simulation environment, specified your analysis frequencies and specified which types of models you wish to create, you may wish to save all these settings, stored in the present state, for use in another design. In order to save all the settings, you select Sonnet Session Save State from the main menu in the layout window. The Save State dialog box appears on your display as shown below. You may enter the name under which you wish to save the state and select which components you wish to include in the state. You may also enter a description of the state in the Description area to help identify the state. This would allow you to save different components such as the Substrate File and Analysis Box to one state and the Frequencies, Options and Calculations in another state. Any existing states are listed in the dialog box. When you click on the OK button, the components you selected are saved to the state name you entered. You may later load this state in another ADS design for which you want to use the same analysis setup. If you wish to save all of the components, you may click on the Select All button. To clear all the checkboxes, click on the Clear All checkbox. See the next section for a discussion of loading a state. 128

129 Chapter 3 Keysight ADS Interface Loading a State Whenever you start a session in the Keysight ADS Interface, all the settings in the interface are set to the present state which is automatically created by the Interface. To use the analysis setup from another ADS design, you must use the Load State command. To load a state, you select Sonnet Session Load State from the main menu in the interface. The Load State dialog box appears on your display. Similar to the Save State dialog box, this dialog box allows you to select a saved state and which components of that state you wish to load. You can select another project in ADS by entering the path in the Project text entry box, or using the Browse button to the right to select a Project on your computer. You can use the Design drop list to select a design in the specified project. Clicking on the Update button will list all the states available in that design. Select the desired state from the list of State Names. If you wish to delete a state, click on it in the list to select it, then click on the Delete State button. When you click on the OK button, the components of the state you selected are loaded into the interface. Please note that these values only affect this session and do not affect the default values. A status window appears on your display to report the progress of the load. 129

130 Keysight ADS Interface Loading the Analysis Setup from the Schematic If you wish to load the analysis setup from the schematic, select Sonnet Session Update All from Schematic. All of the settings will be updated with those from the schematic. Loading the Analysis Setup from Momentum If you wish to load the Analysis Setup from Momentum, select Sonnet Session Update All from Momentum. All of the settings will be updated with those from Momentum. Summary of the Interface You may view a summary of all the settings being used in the Sonnet interface by selecting Sonnet Setup Options Summary of Options. The Sonnet Summary of Options dialog box is opened on your display as shown below. By default all possible options are displayed. If you wish to display only used options, select the Hide Unused checkbox at the top of the dialog box. A Yes or No appears before each option to indicate if the option is being used (this is useful if you are 130

131 Chapter 3 Keysight ADS Interface displaying unused options). If you do not wish this text to appear in the dialog box, select the Hide Yes/No checkbox. You may also click on the View to Print button at the bottom of the dialog box if you wish to print the summary, Hide Unused checkbox Hide Yes/No checkbox Hide Yes/No checkbox View to Print button Running the Simulation Once you have completed the setup of your Sonnet simulation environment, specified your analysis frequencies and specified which type of model you wish to create, you are ready to run the Sonnet EM analysis. Analysis To start the analysis, select Sonnet Analysis Simulate from the layout menu. When you select this command, the software checks the sync date between the ADS layout and the Sonnet project and the stored properties are compared against the actual values in the interface. If these are not in sync, a query window appears. Select yes if you wish to translate and continue with the simulation. 131

132 Keysight ADS Interface TIP You may use the command Sonnet Tools Sync Dates to synchronize the ADS design and layout and the Sonnet project before you run a simulation. This ensures that the Sonnet project is correct before you run the analysis. The ADS layout is translated to a Sonnet project and the Sonnet analysis is started. A status window appears which allows you to track the progress of the simulation. When the Sonnet analysis is invoked, the Sonnet Status dialog and progress bar window, shown below, appear on your display and shows the progress of the simulation. These windows provide you with information about the simulation as it progresses. Simulate and Release For longer analysis runs, you may want to make the license for the Sonnet Keysight ADS interface available in order to work on another project or to allow another user access to the interface. In those cases, you can use the command Sonnet Analysis Simulate Release to run your analysis without locking up 132

133 Chapter 3 Keysight ADS Interface the interface for the whole time. In this case, when you execute the command, the analysis is launched and the license for the Keysight ADS Interface is checked in. Sonnet s analysis monitor appears on your display so you can monitor the progress of the analysis, as shown below. Once the analysis is complete, the interface license is checked back out so you can continue working in the project that was just analyzed. NOTE: When using this option, post-processing is disabled and you must use the utilities provided to generate the model (Sonnet Model Create S-Parameter Model) and dataset (Sonnet Datasets Create Dataset). If you use the simulate and release command to run your analysis, you may stop the simulation in the analysis monitor and use the ABS preview in Sonnet's response viewer. For more information on the ABS preview, please see ABS Preview, page 162 in the Native Environment Guide. Viewing the Subsectioning Once you have completed the setup of your analysis, you may view the subsectioning that will be used by em before you run the analysis. To do this, select Sonnet Tools View Subsection from the main menu in the layout 133

134 Keysight ADS Interface window. The Create Subsections window appears and the subsections are calculated. Once that is complete, the Estimate Memory Results are displayed and Sonnet s subsection viewer is opened showing the subsectioning of your circuit. If calculating the subsections is taking too long, you may select the command Sonnet Tools Abort View Subsections. Estimating Box Resonances Once you have completed the setup of your analysis, you may check for potential box resonances before you run the analysis. To do this, select Sonnet Analysis Estimate Box Resonances from the main menu in the layout window. When you select this command, Sonnet checks your circuit for possible box resonances and outputs the frequencies at which they would occur to the Estimate Box Resonances Results window. If no box resonances are found the message ''None found at or below highest analysis frequency.'' is output to the dialog box. For a detailed discussion of package resonances, see the Chapter 19 "Box Resonances" on page 355 in the Native Environment User s Guide. 134

135 Chapter 3 Keysight ADS Interface Cleaning Analysis Data If you wish to delete all of the analysis data in your translated Sonnet project, you may do so by selecting Sonnet Analysis Clean Data from the main menu in the ADS layout window. Viewing the Results in Sonnet Once the analysis is complete, you may wish to view the response data to evaluate its accuracy before you use the model you created. Both Sonnet s response viewer and current density viewer are available from the Keysight ADS Interface. Sonnet s Response Viewer The response viewer is used to display the results from an em analysis as either a Cartesian graph or Smith chart. S-, Y- and Z-Parameters can be displayed alone or simultaneously as well as transmission line parameters. You can also display multiple curves from multiple projects on a single plot or choose to open multiple plots at the same time. In addition, the response viewer allows you to display the result of equations. There is a set of default equations or the user may define their own. To open the response viewer, select Sonnet Results View Response from the main menu of the layout window. The response viewer appears on your display with the S-parameter DBS11 from your translated Sonnet project displayed as shown below. Examples of using the response viewer are available in the Getting 135

136 Keysight ADS Interface Started with the Native Environment manual. You may also access online help by selecting Help Sonnet Help from the main menu or clicking on the Help button of any dialog box. Curve Name Parameter For an ABS sweep, only discrete data points are shown with symbols. Current Density Viewer If you elect to produce current density data, then you may use the Sonnet Results View Currents command in the layout menu to open Sonnet s current density viewer. The current density viewer is a visualization tool which acts as a post-processor to em providing you with an immediate qualitative view of the electromagnetic interactions occurring within your circuit. To create the current density data, select the Compute Currents option in the Sonnet Options dialog box. For more information, see "Options" on page

137 Chapter 3 Keysight ADS Interface The current density viewer is used to view results from an em analysis as a color shaded plot. The colors can represent either the magnitude of current density or charge. By displaying a sequence of current or charge density plots, each one at a slightly different frequency or phase, the current density viewer can achieve real time animation. The plots shown with the current density viewer give you new insight into the workings of your circuit by showing you the hot spots and cold spots of your circuit. You may then use this information to improve your design and your design skills. The current density viewer can display circuits with any number of ports, dielectric layers, and metal types. You have the ability to change port characteristics and immediately see the effect on your circuit. You may view your circuits using a custom scale determined by you, or take advantage of the current density viewer's auto scaling features. You may also use the current density viewer to see the variable size subsectioning used by em. For detailed information about using the current density viewer, please refer to Help in the current density viewer accessed by selecting Help Sonnet Help from the main menu or the Help button in any dialog box. There is also a short section on using the current density viewer in the first tutorial in the Getting Started with the Native Environment manual. 137

138 Keysight ADS Interface Far Field Viewer If you elect to produce current density data, then you may use the Sonnet Results View Far Field command in the layout menu to open Sonnet s far field viewer. The far field viewer is a radiation pattern computation and display program. It computes the far-field radiation pattern of radiating structures (such as patch antennas) using the current density information from em and displays the far-field radiation patterns in one of three formats: Cartesian plot, polar plot or surface plot. A polar plot is shown below. To create the current density data, select the Compute Currents option in the Sonnet Options dialog box. For more information, see "Options" on page 106. Auto Documentation Sonnet s project editor automatically provides a detailed report on each Sonnet project. Selecting Sonnet => Results Auto Documentation opens a series of HTML pages which contain documentation on your project. This documentation may be printed out or copied for use in other reports or documentation. For detailed information about the Auto Documentation, please refer to Help in the project editor accessed by selecting Help Sonnet Help from the main menu. 138

139 Chapter 3 Keysight ADS Interface Viewing the Results in ADS Once you have successfully analyzed your project in Sonnet, you may manually create a data set in order to plot your results in the ADS Data Display window. This allows you to compare the simulation results from Sonnet to other sources. The name of the dataset is the basename of your design with SonnetEM_Dataset.ds. For example, if your design is named coupled_line then the dataset would be named coupled_line_sonnetem_dataset.ds. Once you have configured a plot in the Data Display, you can save the contents of the plot in ADS as a.dds file. You can also create a dataset automatically at the end of your Sonnet analysis by selecting the Create Dataset checkbox in the Options dialog box (Sonnet Setup Options). Once the analysis is complete in Sonnet, the dataset is created and loaded into the Data Display window in ADS. For more information about analysis options, see "Options" on page 106. Creating a Dataset If you wish to create a dataset from your Sonnet analysis data and view the response in the Data Display window in ADS, you use the Sonnet Datasets Create Dataset command in the Sonnet menu in the ADS layout window. When you select this command, a window appears on your display identifying the response file for which the dataset will be created. An example is pictured below. 139

140 Keysight ADS Interface Click on the OK button in this window to create the dataset. The Data Display window in ADS appears on your display. Use the controls in the Data Display window to create a plot of your response data. An example is illustrated below. Deleting a Dataset The Keysight ADS Interface only allows one dataset per design. If you wish to create a new dataset for the design due to a change in the response data, you must first delete the existing dataset. To delete a dataset, select Sonnet Datasets 140

141 Chapter 3 Keysight ADS Interface Delete Dataset from the Sonnet menu in the layout window in ADS. A browse window appears which allows you to select the desired dataset. Once you have deleted the dataset, this menu item is not enabled until another dataset has been created for this design. Opening a New Data Display If you wish to make multiple plots of the same dataset, you may open a new Display Data window in ADS which uses the Sonnet dataset. To do so, you select Sonnet Datasets New Data Display. An empty Data Display window appears on your display with the Sonnet dataset loaded. Opening an Existing Data Display If you wish to open a previously created data display, select Sonnet Datasets Open Data Display. A browse window appears to allow you to select the desired Data Display file (.dds). Using the Models Creating an S-Parameter Model The S-Parameter Model is in Touchstone format and is created at the end of a Sonnet simulation. Once you have successfully analyzed your project in Sonnet, you create an S-parameter model which you can use as a component in your ADS project. The name of the model is the basename of your design with SonnetEM_SParamModel.dsn. For example, if your design is named coupled_line then the model would be named coupled_line_sonnetem_sparammodel.dsn. This design contains both schematic and layout views. 141

142 Keysight ADS Interface If you wish to create a model from your Sonnet analysis data, you use the Sonnet Models Create S-Parameter Model command in the Sonnet menu in the ADS layout window. When you select this command, the Create S-Parameter Model dialog box appears on your display. When you select this command, the Touchstone S-Parameter File text entry box is automatically filled in with the S-parameter file for the design which is presently open in the ADS Layout window. If you wish to create a model for another design, click on the browse button to the right of the text entry box and select a different S-Parameter file. Model Symbol You may also specify the type of symbol you wish to use for the model: layout look-alike or black box. A layout look-alike uses a small graphic of your layout as the component symbol. The black box uses a small box with the I/O connections. Both types of symbol display the model name. Both types are shown below. Note that some color changes have been done for clarity. Layout look-alike Black Box If you select the layout look-alike as your symbol type, then the controls below, which control the size and appearance of your layout, are enabled. You define the size in terms of a schematic unit. You may use either a layout unit or the minimum pin distance as the size and then enter the equivalent in schematic units. If you 142

143 Chapter 3 Keysight ADS Interface wish to add a ground reference to your symbol, select the Add Ref. Pin checkbox. If you wish to display the pin labels shown in the design from which this model was generated, select the Add Pin Text checkbox. If you wish to generate a layout view of your model using the Sonnet project, select the Generate Layout from Sonnet Project checkbox. When this option is selected, the geometry is re-imported from Sonnet. This allows you to make changes in your Sonnet geometry and update the design in ADS without using the GDSII or DXF translator. The Sonnet project is re-imported into ADS. This allows you to update your design in ADS. Your layout view will appear similar to the geometry in your Sonnet project. If the project displayed in the text entry block below is not the one you wish to use, then click on the browse button to select another. You can also create an S-Parameter model automatically at the end of your Sonnet analysis by setting up the model controls in the Options dialog box (Sonnet Setup Options). Once the analysis is complete in Sonnet, the model and its symbol are created and are available for use in your ADS project. For more information about analysis options, see "Options" on page 106. Viewing the Model To view the model, you may open the schematic, layout or symbol view of the design from the main ADS window or from the Sonnet menu in the layout window from which you generated the model. 143

144 Keysight ADS Interface To view the schematic view of your model, select Sonnet Models View S- Parameter Model Schematic. The schematic view of the model appears on your display and will resemble the schematic shown below. Model Name Model Schematic The response data file on which the model is based. 144

145 Chapter 3 Keysight ADS Interface To view the layout view of your model, select Sonnet Models View S- Parameter Model Layout. The layout view of the model appears on your display and will resemble the illustration shown below. Note that colors are changed in the graphic to increase clarity. Model Name Model Layout 145

146 Keysight ADS Interface To view the symbol view of your model, select Sonnet Models View S- Parameter Model Symbol. The schematic view of the model appears on your display and will resemble the schematic shown below. Model Name Model Symbol Deleting the Model If you wish to delete the Sonnet generated model of a design, open the design in the layout window, then select Sonnet Models Clear S-Parameter Model. 146

147 Chapter 3 Keysight ADS Interface Viewing the S-Parameters You may view the S-parameter output file by selecting Sonnet Models View S-Parameter File. A window appears on your display showing the contents of the S-Parameter file. Translating the Layout to a Sonnet Project If you wish to translate your ADS design layout into a Sonnet project but not execute a simulation, you may use the Sonnet Tools Translate Only command, available in the main menu of the layout window. When you select the command, the Save As Sonnet dialog box appears whose purpose is to display the project to which the translation will be written. You may select any location and project name. When you click on the OK button the ADS design is translated and written to the specified Sonnet project. Sonnet Features Not Available in ADS If you edit the project in Sonnet be aware that there are Sonnet features which may not be used in the ADS Environment. Major features that do not translate are listed below: Parameterization and Optimization: Geometry parameters are available in Sonnet, but may not be used in an ADS design. Therefore, parameterization or optimization of a circuit may not be done from within the ADS environment. 147

148 Keysight ADS Interface However, it is possible to translate the ADS design to Sonnet and run a parameterization or optimization in the Sonnet environment, then use the results to change the geometry in ADS to the optimal values. Reference Planes: You may set a fixed reference plane in the Keysight ADS Interface, but you may not use a linked reference plane where the length of the reference plane is linked to a vertex of a polygon. The following Sonnet features are not available in ADS: dimensions, subdividers, dielectric bricks, calibration lengths, parallel subsections, and symmetry. Using Sonnet s Project Editor If you have access to Sonnet s project editor from the same computer on which you are running ADS, it is possible to open the ADS layout in the project editor. This allows you to tweak the settings or take advantage of features not available in the Keysight ADS Interface. If you do use features not available, it is important to run your simulation and create models which may then be imported into ADS before you translate the layout from ADS again. Translating the circuit from ADS either by using the Translate Only command or the Simulate command will overwrite any features not available in the Keysight ADS Interface. To open Sonnet s project editor, select Sonnet Tools Project Editor 2D View. The Sonnet project translated from your ADS layout is opened in the project editor. If you wish to see a three-dimensional view of your circuit, select Sonnet 148

149 Chapter 3 Keysight ADS Interface Tools Project Editor 3D View. An example of all three views is shown below. The colors in the ADS Layout window view have been changed for clarity in the document. ADS Layout window 2D View 3D View Sonnet s Project Editor 149

150 Keysight ADS Interface Sonnet Task Bar You may also open the Sonnet task bar from the Keysight ADS Interface by selecting Sonnet Tools Task Bar. The Sonnet task bar allows you to access all the modules in Sonnet Software, manage your project files, access the online manuals and Sonnet example files and access various administrative tasks. Utilities in the Keysight ADS Interface Import Mdif File To import an ADS.mdf file, select Sonnet Utilities Import Mdif File from the layout menu. A browse window appears on your display that allows you to locate the Mdif file you wish to import. You may import a file with up to 20 ports. Open Translated Design This utility allows you to quickly switch between your designs in ADS which have been translated to Sonnet. Select Sonnet Utilities Open Translated Design from the main menu of the ADS layout window. A browse window appears which allows you to select the desired design. The selected design is opened in the layout window. 150

151 Chapter 3 Keysight ADS Interface Default Settings for Sonnet You can set up default settings for Sonnet in the Preferences dialog box which are used whenever you open a new layout. The Preferences dialog box, shown below, is opened when you select Sonnet Preferences from the main menu in the layout window. The Preferences dialog box has seven tabs, each covering part of the Sonnet settings. Each tab and its controls is described below. NOTE: Note that for some tab illustrations, the picture differs from what you will see on the display. Unselected options, which are grayed out in the software, have been converted to black typeface to provide clarity for the documentation. 151

152 Keysight ADS Interface States Preferences The first tab in the Preferences dialog box is States, as shown below. This tab determines the Sonnet settings default state and what items you wish to use from the default state in a new design. Enter the desired default state in the Default State Name text entry box. If you wish a setting from the state to be included, select its checkbox. If you do not wish to use the value as the default, clear the corresponding checkbox. 152

153 Chapter 3 Keysight ADS Interface Analysis Box Preferences The second tab in the Preferences dialog box is Analysis Box, as shown below. This tab determines the default box settings for a new design. Use momentum box if it exists:the default values for the analysis box are imported from Momentum if Momentum has been set up for this layout. Automatic update of margins from default below: If you wish to update your box margins in your Sonnet project whenever a change is made in the source used as the default, select this checkbox. Anytime that the Sonnet project is opened, the initial location is checked and any changes made there are updated in the Sonnet project. For an explanation of the controls on the left of the Analysis tab, please see "Defining the Box" on page 93. The Margins section of the Analysis box allows you to set up default margins; the options are described below. 153

154 Keysight ADS Interface Percent (%) of Box Size: Select this choice to set the margins to a length which is a percentage of the box size. When this option is selected, the Value text entry box to the right is enabled; enter the desired percentage here. For example, if the box side is 20 mils on a side and you entered 40%, then the margin for that side of the box would be set to 8 mils. Factor of Substrate Height: Select this choice to set the margins based on the substrate height. The margin will be set to the substrate height multiplied by the value you enter in the Value text entry box. Customized: Select this option to enter a set default value for each of the margins. Whatever value you enter in the four Margin text entry boxes is used as the default margin length on the corresponding box size. None: If you do not want any margins entered by default, select this option. 154

155 Chapter 3 Keysight ADS Interface Substrate Preferences The third tab in the Preferences dialog box is Substrate, as shown below. This tab determines what substrate file is used for a new design. You have six choices of substrates to use for your default settings. For details on the contents of the substrate file, please see "Defining the Substrate" on page 77. Automatic update of substrate from initial location: If you wish to update the substrate definition in your Sonnet project whenever a change is made in the source (selected below the checkbox), select this checkbox. Anytime that the Sonnet project is opened, the initial location is checked and any changes made there are updated in the Sonnet project. Sonnet.matl file: This is a file which contains all the substrate settings. You create a Sonnet.matl file when you use the Sonnet Setup Substrate Export command in the layout view menu. For details, see "Saving a Substrate File" on page

156 Keysight ADS Interface Sonnet.son file: This is another Sonnet project. All of the substrate parameters are taken from the chosen Sonnet project. For details, see "Using an Existing Sonnet Substrate" on page 91. Keysight ADS.slm File: Clicking on this button allows you to use an existing Momentum substrate file as your default. Schematic SUB Statement: This uses a statement from the ADS schematic. If there is more than one, you may select the desired statement from the drop down list. This is equivalent to using the Sonnet Setup Substrate Update from Schematic command. Momentum.slm File: Clicking on this button allows you to use an existing.slm file from Momentum if one is available for the project. None: This option always starts with a blank substrate. 156

157 Chapter 3 Keysight ADS Interface Frequencies Preferences The fourth tab in the Preferences dialog box is Frequencies, as shown below. This tab determines the default analysis frequencies for a new design. Default Frequency Units: Select the default frequency units for new designs from this drop list. Convert schematic linear sweeps to Sonnet ABS sweeps: If you import a frequency plan from an ADS source, then linear sweeps are converted to Sonnet ABS sweeps. This will predictably provide more response data in a shorter analysis time. For a detailed discussion of Adaptive Band Synthesis, see Chapter 7 "Adaptive Band Synthesis (ABS)" on page 149 in the Native Environment User s Guide. Automatic update of frequencies from initial location: If you wish to update your Sonnet project frequencies whenever a change is made in the initial source, select this checkbox. Anytime that the Sonnet project is opened, the initial location is checked and any changes made there are updated in the Sonnet project. 157

158 Keysight ADS Interface Append Frequencies to list on Load: Any new frequencies in the loaded state are added to the existing list of frequency controls. Location to Find Frequency Information: Schematic Frequencies, Momentum Frequencies, both Schematic and Momentum Frequencies, and None. Selecting Schematic Frequencies will load any frequency controls set up in the schematic of the design. Momentum Frequencies loads any frequencies set up for the design in Momentum. Schematic and Momentum Frequencies will combine the two sets of frequency controls and None will not load in any default frequencies. Ports Preferences The fifth tab in the Preferences dialog box is Ports as pictured below. This tab determines the initial source from which the ports for the Sonnet project are taken. 158

159 Chapter 3 Keysight ADS Interface Automatically update of ports from initial location: If you wish to update your Sonnet project ports whenever a change is made in the source, select this checkbox. Anytime that the Sonnet project is opened, the initial location is checked and any changes made there are updated in the Sonnet project. Initial Location to Find Port Information: This identifies the source from which the Sonnet project obtains the initial port definitions. You may select Layout Ports which will translate any ports which appear in the layout view to the Sonnet project. The other source is Momentum ports, which uses any ports defined in the Momentum design which is being translated into Sonnet. ABS Options The sixth tab in the Preferences dialog box is ABS Options. This tab contains the Advanced ABS Options you wish to use by default. For an explanation of the ABS options, please see "Advanced ABS Settings" on page 113. Model Options The seventh tab in the Preferences dialog box is Model Options. This tab contains the default settings you wish to use for creating your model and data set. For an explanation of the Model options, please see "Model Options" on page 120. Project Options The eighth tab in the Preferences dialog box is Project Options. This tab contains the default settings you wish to use your analysis run options. For an explanation of the Project options, please see "Project Options" on page 115. Simulation Program Options The ninth tab in the Preference dialog box is Simulation Program Options. This tab allows you to select the default server upon which you will execute your Sonnet simulations. For an explanation of the Simulation Program Options, see "Simulation Program" on page

160 Keysight ADS Interface Subsectioning Options The tenth tab in the Preference dialog box is Subsectioning Options. This tab allows you to select the default settings to control how your Sonnet project is subsectioned for the analysis. For an explanation of the Subsectioning Options, see "Subsectioning" on page 107. Translation Options The eleventh tab in the Preferences dialog box is Translation Options. This tab allows you control the default translation options that control how your ADS layout is translated to a Sonnet project. For an explanation of the Translation Options, see "Translation Options (ADS to Sonnet)" on page

161 Chapter 3 Keysight ADS Interface Other Preferences The twelfth, and last, tab in the Preferences dialog box is Other, as shown below. The controls are detailed below. Show warning of sub designs: Setting this checkbox causes a warning to be issued if there are sub-designs (the layout has not been flattened). Show status dialog: Setting this checkbox displays the status dialog box. Hide Unused in Summary Options: Setting this checkbox causes the Summary page to default to displaying only used options. See Summary of the Interface, page 130 for more information. 161

162 Keysight ADS Interface Hide Yes/No in Summary Options: Setting this checkbox causes the Summary page to not display the Yes/No field which indicates an option is being used. See Summary of the Interface, page 130 for more information. Customized Sonnet Box Drawing Layer: It is possible to create a custom sized box for your Sonnet analysis by drawing the box size in your layout view. See "Sonnet Custom Box" on page 99 for details on how to do this. In order to input this box size, ADS requires a drawing layer upon which an object is drawn which represents the box size. This object is not translated into the Sonnet project, but the interface uses this object to set the Sonnet box size in the translated Sonnet project. This option allows you to enter the name of the drawing layer that is used to define the custom Sonnet box. The default value is sonnet_box. If the default value is used, then a drawing layer named sonnet_box should be added to the design in ADS. You may also input another drawing layer name from your design that you wish to use.! WARNING Do not place any additional objects on the Sonnet Box Drawing Layer as they are not translated. Also, if another option is used to define the box size, the Sonnet Box Drawing Layer is deleted from the layout which would include any additional objects placed on this layer. Temporary Sonnet Box Drawing Layer: There is an option in the Analysis Box dialog box (Sonnet Setup Analysis Box Edit) that when selected causes an outline to appear in the layout window which represents the box size defined in the Analysis Box dialog box. This outline only appears when the Analysis Box dialog box is opened. A drawing layer is required on which this outline may be placed in order for it to appear in the layout. This option allows you to enter the name of the temporary drawing layer. The default name is temp_sonnet_box. If the default value is used, then a drawing layer named temp_sonnet_box should be added to the design in ADS. You may also input another drawing layer name from your design that you wish to use. 162

163 Chapter 3 Keysight ADS Interface NOTE: The Sonnet Box is only displayed when the Analysis Box dialog box is opened in the interface and the Show Box option is selected in that dialog box as well. This means that the Sonnet Box Temporary Drawing Layer is not always visible so that any additional objects placed on this layer will not always appear in the layout window. Priority Momentum emsetup Cell View: Momentum can now have multiple states for a cell view which includes such information as the layout, substrate, ports, analysis freqs, etc. When a layout is translated into Sonnet, if Momentum has multiple states, then the Priority Momentum emsetup Cell View option defines which state is given priority and used for the translation into a Sonnet project. The default entry for this option is emsetup. Any name may be used for this cell view as long as the state using that name has been created in Momentum. That state should contain the information that you wish to use for your Sonnet simulation. Keysight ADS License Check You may check to see if you have a valid Keysight ADS license for Sonnet and your ability to both check a license out and check the license back in. To check for license availability, select Sonnet Help Support Check License from the main menu of the layout window in ADS. The Status Dialog window appears and provides status on the license. Pictured below is a successful license check. 163

164 Keysight ADS Interface Unlocking Sonnet Keysight ADS Interface When you are running a simulation using the Analysis Simulate command, the Keysight ADS Interface is locked until the analysis is complete. You may not make any changes or execute any commands in the interface until it is unlocked when Sonnet is closed. If for some reason the Sonnet program is interrupted in such a way as to prevent a graceful shutdown, such as a hung program or a program crash, then the Keysight ADS interface is not unlocked. In this case, you may manually unlock it by selecting Sonnet Analysis Unlock Project from the main menu of the ADS layout window. 164

165 Appendix I Via Simplification Appendix I Via Simplification Introduction Several manufacturing processes used to produce RF circuits utilize via arrays or bar via groups to provide the trace metal layer to layer connections. Both of these types of vias present an analysis challenge which drives the Sonnet model memory and analysis time requirements beyond what is practical to analyze. Via simplification provides an approach to via arrays and bar vias that reduce the time and memory requirements without sacrificing accuracy. These two processes are discussed in this appendix. Via Array Simplification For via arrays, the small size of the individual vias and the large number in the array usually drive Sonnet model memory and analysis time requirements beyond what is practical to analyze. This often requires that you simplify the via geometry detail before performing your EM simulation. In the past, via array simplification would need to be done manually by deleting vias and replacing with a single, larger via polygon. 165

166 Keysight ADS Interface The Simplify Via Array feature automatically performs this simplification during the translation process. It can be invoked inside the Cadence Virtuoso Interface. It may also be invoked in Sonnet s project editor when performing an import using the GDSII Translator or DXF Translator. NOTE: Via array simplification is only used when running an EM simulation using the Accurate Solver. Via Array Criteria There are six criteria, all of which must be met, before a group of vias in the original geometry is considered an array and therefore simplified by the software. Number of Vias: There must be a minimum number of vias in order for them to be considered an array. Via Size: The vias must be the same size or nearly the same size. Via Spacing: The vias must be within a certain distance of one another. Layer Pass Through: The vias must pass through the same layer(s). Metal Polygons Pads: The vias must be contained within the same metal polygon at either the top or the bottom of the vias. Material: The vias must be set to the same material, whose conductivity is the same. Additional Simplify Via Array Options This text entry box should only be used at the direction of a Sonnet representative. Simplify Via Array Options There are six control options for the simplify via array feature which are discussed in detail in the following sections. We will use a simple example circuit to illustrate how the options affect the via simplification. 166

167 Appendix I Via Simplification TIP The default values were determined based on extensive testing, and in the majority of cases will provide reasonable via simplification behavior. However, Sonnet handles a wide range of layouts and processes, so these controls were provided so that a user can customize the translation if it proves necessary. The example structure consists of three metal layers and two interconnecting via arrays, as shown below. Since the vias pass through different dielectric layers and use different metal types, the 1 X 2 array and the 5 X 5 array would never be grouped together. Either reason would be sufficient on its own to prevent these two arrays being grouped together. The 1 X 2 via array extends from metal level 0 to metal level 1 through the upper dielectric layer. The 5 X 5 via array extends from metal level 1 to metal level 2 through the lower dielectric layer. 1 X 2 via array. Each via is 1 μm square and the assigned metal type is Via1. 3D View of circuit 5 X 5 via array. Each via is 4 μm square and the assigned metal type is Via2. 2D View of Metal Level 1 167

168 Keysight ADS Interface Minimum Vias in Array This control defines the minimum number of vias which can be considered part of the same array. The default value for this setting is 5, so that only arrays with 5 or more vias will be considered for simplification. Therefore, in our example the 1 x 2 via array would not be simplified, but the 5 X 5 would be analyzed to see if this array meets the rest of the simplification criteria. You may enter any integer value to set the minimum number required. 1 X 2 Via array Will not be simplified 5 X 5 Via Array Will be simplified Max Distance to Size Ratio This control defines the maximum spacing between vias which can be considered part of the same array. While the distance between vias is measured from the center lines of the individual vias, the control is a ratio of distance to via size. This distance cannot exceed the value of this ratio multiplied by the via size. The default setting is 4.0 and the larger the value, the more widespread the vias can be and still be grouped in the same array. Since individual via cross-sections can be of any shape, the square root of the via area is used as the via size. 168

169 Appendix I Via Simplification For our example the size of the vias is 2.0 μm and the center to center spacing is 4.0 μm, as pictured below. This results in a Distance to Size ratio of 4.0/2.0 = 2.0 so that this array meets the via spacing criteria. The center to center spacing is 4 μm. The size of an individual via is 2μm. Maximum Size to Size Ratio This control defines the maximum allowable difference in via size to be considered part of the same array. The default value of this ratio is 1.5 and the larger the value, the greater the difference of via size is allowed within an array. Since individual via cross-sections can be of any shape, the square root of the via area is used as the via size. For this example, the via cross-section is a 2.0 X 2.0 μm square. The area is 4 μm 2 and taking the square root, yields a via size value of 2 μm. Since all of the vias are the same size in this array (2.0 μm) the Size to Size ratio is 1.0, so that this array meets the via size criteria. TIP If you wish to limit your arrays to vias of the same size, set this control to 1.0. Max Expansion Coefficient This control helps define the size of the resulting simplified via by allowing it to be larger than the original via array perimeter (also referred to as the bounding box). The default value is 7.0, which allows the simplified via to expand outward by a factor of 7 times the largest via size in the array. The advantage in expanding 169

170 Keysight ADS Interface the simplified via is that it can often be sized to match the polygons to which the via attaches. Having the via polygon edge and pad polygon edge in alignment can significantly reduce the subsection density in the region and thereby reduce the memory requirement of the model. An example is shown below. The algorithm looks outward from an imaginary rectangle (bounding box) drawn around the perimeter of the array (green rectangle). The distance checked out from the perimeter is the Max Expansion Distance (shown in red arrows). It is equal to the Max Expansion Coefficient times the largest sized existing via in the array. If a vertex from a pad polygon is encountered within this window (red rectangle), the expansion stops and this sets the simplified polygon edge. If no vertices are found in a particular direction, the edge of the simplified via rolls back to the existing via array perimeter. Please note that all metal levels are examined when looking for vertices within the maximum expansion distance. The Max Expansion Distance is denoted by the red dashed box and is 7.0 times (default value) the largest via size (2.0 μm) = 14.0 μm. The blue stars are vertices within the max expansion distance on this metal level. The yellow star indicates a vertex found on another metal level. The via array perimeter is indicated by the dashed green box. If no vertices are found in that direction, then the perimeter defines the edge of the simplified via in that direction. The dashed blue box above shows the final size of the simplified via. On the top, bottom and right hand side the via extends to the vertices and on the left side it conforms to the array bounding box (dashed green box) since no vertices were found within the maximum expansion distance in that direction. 170

171 Appendix I Via Simplification TIP The default setting for Max Expansion Coefficient is 7.0. If you wish the simplified via to be the bounding box around the array, set the Max Expansion Coefficient to 0, which allows no expansion. Merge Planar Polygons During Simplification In order to be considered an array, a group of vias must connect to a single polygon on the top and bottom of the group. This control allows the user to merge the polygon pads or traces prior to simplifying the vias. This results in larger arrays being recognized leading to the least number of simplified vias, thereby producing the most efficient model. This option is enabled by default. The option is illustrated below using the example circuit. The trace is divided into two parts (black outlines show the two polygons). If the Merge Planar Polygon option is not selected, then the array is treated as two via arrays (indicated by the dashed red boxes) and two simplified vias are created. If the option is on, however, the two parts of the trace are merged into one polygon and the whole array is simplified into one via. NOTE: The polygons are only temporarily merged for via simplification and will not be merged in the resulting Sonnet project. 171

172 Keysight ADS Interface Number of New Via Metals Created Via metal types using the Array loss model are created to model your simplified vias in Sonnet. This setting controls how many via metal types are created in your translated project in order to model your simplified array. The fill factor is used to determine how many metal types are created. For more information on the fill factor and the Array loss model, please see Array Loss Model in the Native Environment User s Guide. There are three choices: Minimum: Creates the least number of via metal types but may be less accurate as a wider range of fill factors will be grouped together. Automatic: Creates the via metal types based on an algorithm that balances the trade off between accuracy and the number of via metal types produced. This is the default setting. Maximum: Creates the highest number of via metal types providing the most accurate answer since a via metal type is created for each unique fill factor. Simplified Via Array Loss When an array is converted to a simplified via, a via metal type using the Array Loss model is created, if it does not yet exist. For example, you are translating an array which uses ViaMetal1 for an array. During the translation a via metal type ViaMetal1 is created that uses the Array Loss model. During translation, one source metal may be translated into two metal types if there is a significant difference in individual via size in different arrays using the same metal. For more information about via metal types and defining their loss, please see Array Loss Model, in the Native Environment User s Guide. The simplified via is modeled using the same meshing fill as the vias in the original via array. For a detailed discussion of meshing fill for via polygons, please see Meshing Fill for Vias in the Native Environment User s Guide. 172

173 Appendix I Via Simplification Bar Via Group Simplification Bar vias are vias whose length is significantly longer than their width. They are typically used in stacked multi-level conductors where vias carry horizontal currents. An example is shown below, with one of the bar vias highlighted in black. For vias whose aspect ratio is smaller, such as 1:1, the Sonnet model assumes that there is little to no horizontal current in the via. The assumption is that current flows in the vertical or z-direction. For bar vias, whose aspect ratio is larger, the current flow in the horizontal direction is more significant. Bar via groups placed on metal traces also drive a very fine resolution in the meshing that can require an inordinate amount of processing resources. The Identify Bar Vias feature identifies bar vias in the translated circuit based on length to width ratio entered by the user. These vias are assigned the Bar via meshing fill, then during the analysis multiple adjacent bar vias are identified as a bar via group and merged into one wider via during the subsectioning by the analysis engine, em. Since via arrays are simplified during translation, their appearance in the project editor is that of the simplified via polygon into which the via array was converted. However, in the case of bar vias, the actual via polygon input by the user is displayed in the project editor, because no simplification has yet been done. If you wish to see the actual metal for the simplified bar vias that are used in the simulation, you should view the subsections for the circuit. For a detailed 173