High Speed and High Power Connector Design

Transcription

1 High Speed and High Power Connector Design Taiwan User Conference 2014

2 Introduction High speed connector: Electrically small Using differential signaling Data rate >100Mbps High power connector: Static to low frequency Carrying high current Consideration of thermal and mechanical effects

3 Typical Connector Design Workflow Design Virtual Prototype Analysis Measurement Manufacture Optimization

4 Connector Simulation Workflow Pre- Processing 3D CAD import Material definition PCB test fixture Solver Choice T-Solver F-Solver Post Processing TDR TDR cross probing S-parameter Eye diagram SPICE / Touchstone

5 Connector Simulation Workflow Pre- Processing 3D CAD import Material definition PCB test fixture Solver Choice T-Solver F-Solver Post Processing TDR TDR cross probing S-parameter Eye diagram SPICE / Touchstone

6 Material Definition Copper Alloy International Annealed Copper Standard (IACS) Copper reference conductivity 58M S/m as 100% 27% IACS conductivity 15.66M S/m * Data taken from First Copper Technology Co., LTD.

7 Material Definition - Substrate Dispersive material with Eps_r(f) The dielectric dissipation factor or tangent of the loss angle describes the losses Higher order dispersion model * Data taken from VECTRA LCP material (E130i)

8 Connector Simulation Workflow Pre- Processing 3D CAD import Material definition PCB test fixture Solver Choice T-Solver F-Solver Post Processing TDR TDR cross probing S-parameter Eye diagram SPICE / Touchstone

9 Solver Choice High geometrical complexity Broadband results Memory efficient Online TDR True transient co-simulation Electrically small structures Narrow band frequency range Many ports (direct solver) Conformal mesh (curved elements) Automatic energy based mesh adaptation

10 Connector Simulation Workflow Pre- Processing 3D CAD import Material definition PCB test fixture Solver Choice T-Solver F-Solver Post Processing TDR TDR cross probing S-parameter Eye diagram SPICE / Touchstone

11 Connector Design Tools What matter in connector design is impedance TDR (Time Domain Reflectometry) Impedance profile in time S-Parameter Frequency domain IL and X-Talks SPICE Extraction

12 TDR Response from Different Termination Zo ohm termination Short Open End time of TDR response shows the defined termination impedance TDR response up to 0.5ns remains the same independent from open or short termination

13 TDR Response from Different Environment Impedance overshoot Series L discontinuity Impedance undershoot Shunt C discontinuity Impedance overshoot & undershoot Combination L & C

14 Excitation Signal Step function Spectrum contains zero amplitude No meaningful s-parameter Gauss signal Wideband spectrum S-parameter results Z( t) i Zo i o( t) o( t) TDR response Z( t) Zo i( t) dt i( t) dt o( t) dt o( t) dt Recommended excitation signal: Gauss signal

15 TDR Resolution and Rise Time Faster rise time includes higher frequency content t 10~90% rise f max Higher frequency means smaller wavelength Smaller wavelength leads to a better resolution of discontinuities

16 TDR Response Different Rise Time TDR response of ohm loss free MS line Rise time in ns Pick the correct rise time based on the high-speed digital standard technologies and not by minimum distance of the discontinuities

17 Effect of Loss on TDR Response Lossy medium: attenuates the spikes and dip in TDR response decreases the rise time degrades the TDR resolution

18 Z(t) TDR Cross Probing Locating the discontinuity using the TDR Cross probing Only available in time domain solver Requires 3D time domain power flow result monitor

19 S-Parameter Scattering parameter describes the DUT performance Insertion loss, e.g. S21 Return loss, e.g. S11 X-talks: Near end x-talk, e.g. S31 Far end x-talk, e.g. S41 S11 Reconstruction of TDR response from return loss (reflection coefficient) S DUT 3 4 S31 S41

20 S-Parameter Result Typical S-Parameter results TDR response from the return loss

21 Connector Examples DisplayPort USB 3.0 High Speed Backplane Connector Power Connector

22 DisplayPort Connector Consists 1,2 or 4 differential data pairs 5.4Gbps raw data rate for each lane DisplayPort plug model DisplayPort receptacle model Joint model with activated cutting plane view

23 PCB Test Fixture and Excitation Port Waveguide port with differential signal definition Line impedance and differential mode pattern are automatically calculated

24 Simulation Setting Copper 100% IACS Plastic housing with Eps_r=4 and TanD=0.02 Fmax 6GHz ~ Trise=146ps T-solver with hexahedral mesh Energy decay -40dB Open boundary in all direction Hexahedral mesh view in x-normal plane

25 Z(t) TDR Result (Open End) Data line 1 Data line 2 h1 Time / ps h1>h2 higher parasitic inductance at data line 1 h2

26 Z(t) TDR Result Interior Design Modification w1 h1 Compensate the parasitic capacitance Increase the width space w1 100um Increase the height space h1 50um

27 Z(t) TDR Result Design Modification Adding simplified plastic cover at launcher Time / ps Add plastic cover at launcher helps to compensate the parasitic inductance Introduces higher parasitic capacitance Improve the TDR at the launcher (200ps-400ps)

28 S-Parameter Results Original Connector Modified Connector Return loss has been improved Staggered signal pin assignment helps to keep X-talk low - + G G G

29 Eye Diagram PRBS N=7 eye height= 0.94 eye width= 190ps 5Gbs data rate with trise=130ps Good insertion loss and low cross talk level results in proper eye opening

30 Example 2 USB 3.0 Standard A-Connector

31 USB 3.0 Standard A-Connector Same interface as USB 2.0 standard A-connector, but with added Superspeed USB Signal which offers 5 Gbps signal rate, 10x faster than Hi-Speed USB 2.0 Compatible with the USB 2.0 standard A-connector STP (Shielded Twisted Pair) used for USB 3.0 and Unshielded Twisted Pair (UTP) for USB 2.0 USB 3.0 Differential Signal Pair (STP) GND USB 3.0 Differential Signal Pair (STP) GND USB 2.0 Differential Signal Pair (UTP) Power

32 3D Simulation Settings Differential mode with 90ohm impedance Mated connector Fmax=11.52GHz for 50ps Trise (20%-80%) T-solver hexahedral mesh (22M mesh) Energy decay -40dB Open boundary in all directions Copper 100% IACS and LCP for plastic component Simplified 3D Cable Cross section

33 Cable Construction 3.3dB 2.5GHz Model of USB3.0 cable cross section using CST CABLE STUDIO Low insertion loss at 2.5GHz for 3m long USB 3.0 cable * Data taken from Universal Serial Bus 3.0 Specification

34 Z(t) Differential TDR mated connector Time / ns

35 Differential Insertion Loss Differential insertion loss for mated cable assembly Mated connector Input Mated connector Output USB 3.0 cable Circuit simulator CST DESIGN STUDIO Frequency / GHz 5.3dB

36 Differential Crosstalk Differential NEXT Crosstalk between the USB 3.0 differential pairs Frequency / GHz -45dB

37 Eye Diagram UI = 200ps 5Gbs data rate Eye width and height are calculated from the center UI minimum eye width minimum eye height

38 Example 3 High Speed Backplane Connector

39 Daughter card side Backplane Connector Backplane side Differential pair pin assignments Up to 20Gbs data rate for each differential pair Staggered pin configuration and edge-coupled design to achieve low loss and low cross talk

40 Simulation Settings Mated connector Fmax=30GHz T-solver with hexahedral mesh (17M mesh) Open boundary in all directions -40dB energy decay Conducting material: Brass (28% IACS) Non-conducting material: LCP Simplified PCB test fixture (output) Simplified PCB test fixture (input)

41 Z(t) Differential TDR TDR with 50ps (10%-90%) Modification of interior design to meet the TDR specification A B C D E F G H I J Time/ns

42 Z(t) Interior Modification Time/ns

43 Differential Insertion Loss A B C D E F G H I J Frequency / GHz Losses for the selected pairs are within the limit <1dB for 6Gbs (3GHz) <2dB for 20Gbs (10GHz)

44 NEXT (%) Differential Crosstalk (NEXT) Crosstalk measurement always on daughter card side: NEXT measurement: Signal injected on daughter card side. NEXT <3.25% with 50ps (10%-90%) NEXT 1 Peak Peak NEXT: 1.2% Time/ns in NEXT 2

45 FEXT (%) Differential Crosstalk (FEXT) FEXT measurement: Signal injected on backplane side FEXT <5.75% with 50ps (10%-90%) in Peak Peak FEXT: 1% FEXT 1 Time/ns FEXT 2

46 Crosstalk (%) Worst Case Crosstalk Peak Peak NEXT: 2.7% Time/ns Multi-pair-active crosstalk when the signal is injected from all adjacent pairs. One victim pair and six aggressor pairs

47 Eye Diagram PRBS N=7 eye height= 0.9 eye width= 90ps Eye diagram from the center output port at daughter card side with UI=100ps (20Gbs) Circuit simulation time using 40x40 s-matrix SPICE equivalent network extraction: 12m Transient simulation: 40s

48 Example 4 Power Connector

49 Multidisciplinary Approach Losses in material introduced from HF EM-field Structure deformation detunes the HF-performance Temperature increment as the result of losses Losses in material introduced from stationary or LF EM-field Increasing of temperature leads to structure deformation

50 Simulation Setup Input 6x 7.5A Simulation of mated connector DC current for each cable 7.5A Brass material for pin and socket Nylon material for housing Additional material parameter definitions: Thermal conductivity Thermal expansion coefficient Young s modulus Output

51 Simulation Workflow Stationary current solver Current distribution Export thermal loss Stationary thermal solver Source: thermal loss Temp. distribution Heat flow Automatic update all tasks! original structure Structural mechanic solver Source: temp. distr. Deformation deformed structure

52 Conclusions Pre-processing: Supports various formats of 3D CAD import (CATIA, Pro-E, STEP, etc.) and various formats of PCB layout (ODB++, Zuken, Cadence, etc.) Realistic material parameter modeling for HF and Multiphysic simulation Realistic cable modeling using CST CABLE STUDIO Complete technology T! and F! offer flexibility to choose most efficient solver HPC computing supported from both solvers Post processing: Automatic line impedance calculation, TDR, s-parameter and eye diagram Fast and accurate circuit simulation using CST DESIGN STUDIO Seamless simulation workflow for system simulation