Agilent EEsof EDA. Implementation of Touchstone Version 2.0 in ADS New Features for Solving HSD Challenges with ADS 2013

Transcription

1 New Features for Solving HSD Challenges with ADS 2013 Implementation of Touchstone Version 2.0 in ADS Agilent EEsof EDA Radek Biernacki June 17/18/20, 2013 Copyright 2013 Agilent Technologies 1

2 Outline Why Touchstone 2.0 ADS Implementation Touchstone 2.0 Format Notes on differential ports Notes on mixed-mode n-port parameters Some hints for using Touchstone data Copyright 2013 Agilent Technologies 2

3 Historical Note S-parameters have been used for many decades to characterize linear sub-circuits, passive and active devices, interconnects, EM co-simulation, etc. Growing interest in S-parameter representation of linear sub-circuits among the SI/PI engineers. PI engineers observed improved accuracy when different reference impedances were used for power than those for signal ports. The legacy Touchstone format accommodated only the same reference impedance for all ports. Copyright 2013 Agilent Technologies 3

4 The Role of the IBIS Open Forum IBIS Open Forum is a standardization organization that supports I/O buffer modeling (I/O Buffer Information Specification) with the focus on signal and power integrity. The IBIS organization took the initiative to standardize on the Agilent s Touchstone format. With Agilent s permission the official Touchstone File Format Specification Version 2.0 has been developed, and ratified in Copyright 2013 Agilent Technologies 4

5 Notes on Per-Port Reference Impedances ADS has always allowed different per-port reference impedances CITI files datasets This included complex reference impedances, useful for power match In view of several ways to deal with complex impedances, IBIS decided to it was sufficient to allow real impedances only. Copyright 2013 Agilent Technologies 5

6 Version 1.0 Format The original Touchstone File Format had never been officially standardized, though it was a de-facto standard. A few of the original rules have been slightly relaxed with time, including three character file name extension as needed for more than 9-port data (e.g., *.s12p) reliance on the file name extension limited number of data items per line The IBIS standardization initiative included also the legacy Touchstone files. They are now referred to as Version 1.0 files. This has effectively put an end to somewhat uncontrolled attempts to extend the original format by various vendors. Copyright 2013 Agilent Technologies 6

7 A Typical Version 1.0 File! Created Fri Nov 21 11:25: # Hz S MA R 50! freq mags11 angs11 mags21 angs21 mags12 angs12 mags22 angs22 1e e e e e ! 2 Port Noise Data 1e+009 3e+009 5e+009 Copyright 2013 Agilent Technologies 7

8 Example of an Illegal Extension in a Legacy Touchstone File! Four port data with different per-port reference impedances # Hz S MA R ! freq mags11 angs11 mags12 angs12 mags13 angs13 mags14 angs14! freq mags21 angs21 mags22 angs22 mags23 angs23 mags24 angs24! freq mags31 angs31 mags32 angs32 mags33 angs33 mags34 angs34! freq mags41 angs41 mags42 angs42 mags43 angs43 mags44 angs44 1e We have no plans to support such non-standard extensions. A file like this can be easily converted to a Version 2.0 file. Copyright 2013 Agilent Technologies 8

9 Touchstone 2.0 Implementation in ADS Release Import (read) yes complete features all SnP, SnP_Diff and De_Embed components no for the DAC component (use SnP directly) Export (write) yes Touchstone 1.0 (as before) no Touchstone 2.0 (for now) SPOutput, Data File Tool, TouchstoneCombiner Copyright 2013 Agilent Technologies 9

10 Touchstone 2.0 Implementation in ADS Release cont d Familiar SnP components User does not have to identify the file version or act upon it! Copyright 2013 Agilent Technologies 10

11 Touchstone 2.0 Implementation in ADS Release cont d All existing features of the SnP components are preserved: interpolation techniques linear, cubic cubic splines a few others interpolation domain real/imaginary magnitude/angle db/angle extrapolation options passivity checking/enforcement causality enforcement Copyright 2013 Agilent Technologies 11

12 Touchstone 2.0 Distinct Features different reference impedances allowed for different ports mixed-mode n-port parameters includes the S, Y or Z matrix types format (IBIS style keywords) precise rules and specification Copyright 2013 Agilent Technologies 12

13 Touchstone Version 2.0 vs. Version 1.0 Minor Differences Z, Y, G, H matrices and Noise Resistance are no longer normalized. Two-port data special order (S11, S21, S12, S22) is not required. It is allowed to specify either the full matrix or the lower/upper half matrix. Copyright 2013 Agilent Technologies 13

14 Touchstone 2.0 Version Keyword and Option Line [Version] 2.0 the first keyword in the file required in Version 2.0 files prohibited in Version 1.0 files The Option line is the same as in legacy files and it determines the units, data type, data format and the reference impedance, for example # GHz S MA R 50 required in all Touchstone files Copyright 2013 Agilent Technologies 14

15 Touchstone 2.0 Number of Ports and Number of Frequencies Keywords [Number of Ports] 6 required in Version 2.0 files prohibited in Version 1.0 files [Number of Frequencies] 501 required in Version 2.0 files prohibited in Version 1.0 files Copyright 2013 Agilent Technologies 15

16 Handling Different Reference Impedances in Touchstone 2.0 Files [Reference] optional in Version 2.0 files prohibited in Version 1.0 files overrides the reference impedance setting in the Option line The order of the entries must follow the port ordering (the same as the row/column ordering in the data matrices). The number of entries must equal the number of ports. Complex reference impedances are not allowed. Copyright 2013 Agilent Technologies 16

17 Network Data in Touchstone Files The actual n-port data is similar for both versions, but the [Network Data] keyword is required in Version 2.0 files prohibited in Version 1.0 files There are no limitations regarding the number of data items in a single line. Copyright 2013 Agilent Technologies 17

18 Some Other Keywords in Touchstone 2.0 Files [Two-Port Data Order] 12_21 required in Version 2.0 files for 2-port data, otherwise prohibited the order is pre-defined as 21_12 in Version 1.0 files [Matrix Format] Lower optional in Version 2.0 files for specifying Full, Lower, or Upper the order is pre-defined as 21_12 in Version 1.0 files [Number of Noise Frequencies] 151 [Noise Data] [End] Copyright 2013 Agilent Technologies 18

19 Example of Version 2.0 File [Version] 2.0 # Hz S MA R 50 [Number of Ports] 2 [Two-Port Data Order] 12_21 prohibited! Required for 2-port data; otherwise [Number of Frequencies] 5 [Reference] impedance is used [Matrix Format] Full! Optional if the same reference! Optional Full is the default [Network Data]! freq mags11 angs11 mags12 angs12 mags21 angs21 mags22 angs22 1e [Number of Noise Frequencies] 3 [Noise Data] [End] 1e+009 Copyright 2013 Agilent Technologies 19

20 Extensions in Version 2.0 Files [Version] 2.0 # Hz S MA R [Reference] 50 1 [Matrix Format] Lower!or Upper [Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1 [Begin Information] Any useful information for the user, but no action by EDA platforms [End Information] [End] Copyright 2013 Agilent Technologies 20

21 Notes on Differential Circuit Ports I1 P1+ one differential port consists of two normal singleended ports. + V1 P1- The - node is common for the two single-ended ports. Therefore, differential ports are 3-terminal objects; however, as we prefer to have just one (common) reference terminal for all the ports they may be perceived as 2-terminal objects beware! Vdiff I1 The mixed mode currents and voltages are linear combinations of the respective single-ended currents and voltages. - I2 P2+ V2 P2- In Touchstone 2.0 it is required that the reference impedances for the two ports that form one differential port are identical. Icommon I2 Copyright 2013 Agilent Technologies 21

22 Mixed-Mode Quantities common mode voltage differential mode voltage common mode current differential mode current, /2,,, /2 common mode incident wave differential mode incident wave common mode reflected wave differential mode reflected wave,,,, / 2, ),,,, / 2, ),,,, / 2, ),,,, / 2, ) Copyright 2013 Agilent Technologies 22

23 Mixed-Mode n-port Parameters in Touchstone Version 2.0 Files Whether the file contains single-ended or mixed-mode n-port data (under the [Network Data] keyword) is determined by the presence of the following keyword. [Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1 optional in Version 2.0 files; indicates that the mixed-mode data rather than the singleended data is given prohibited in Version 1.0 files the order of the entries follows the row/column ordering in the data matrices indices correspond to single-ended port ordering, consistent with the port ordering in the SnP symbol in the UI D indicates a differential quantity, C indicates a common mode quantity and S indicates the single-ended quantity for ports that are not a part of any differential port Copyright 2013 Agilent Technologies 23

24 Interpretation of [Mixed-Mode Order] [Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1 Copyright 2013 Agilent Technologies 24

25 Hints Using Datasets Parsing may be time consuming for large number of ports create and use datasets. binary files using ADS internal data structure faster to read no need for interpretation easily viewable in Data Display Simply run S-Parameter simulation. Copyright 2013 Agilent Technologies 25

26 Hints Verify Data Quality View S-Parameter simulation results in Data Display. Bad data may significantly affect the simulation results! Copyright 2013 Agilent Technologies 26

27 Hints Impact of Bad Data Example of what incorrect DC extrapolation may lead to. Copyright 2013 Agilent Technologies 27

28 Hints Eliminate Unused Ports Two techniques. 1. load unused ports run S-Parameter simulation on a subset of original ports subsequently use an n-port with fewer ports pay attention to the frequency plan and coverage 2. use the following unique ADS feature Copyright 2013 Agilent Technologies 28

29 Hints Large SnP Reduction OPTIONS Options Options1 Temp=25 Tnom=25 V_RelTol= V_AbsTol= I_RelTol= I_AbsTol= GiveAllWarnings=yes MaxWarnings=10 Copyright 2013 Agilent Technologies 29

30 Summary ADS has always allowed the use of different per-port reference impedances for S-parameter data, yet the Touchstone files required the same value for all ports. Touchstone Version 2.0 relaxes those limitations and unambiguously defines the allowable format. Touchstone 2.0 provides the means to handle mixed-mode n-port data. In ADS the new format is adapted in a completely transparent fashion. The user can use the new files exactly the same way the old files were used. Copyright 2013 Agilent Technologies 30