automotive simulation congressregister.ansys.com.cn/ansyschina/20151117aswc/molex... ·...

June 2-3 . Detroit , USA

Automotive Connector Simulation vs Measurement

A Case Study

Sungjong Yoo, Ph.D, Electrical Design Engineer, Molex Inc.

David Dunham, Director Electrical Engineering, Molex Inc.


Overview

�What this presentation will cover

– Typical Automotive Cable & Connector Assembly

– HFSS Simulation Setup

– Correlated results of a Typical Automotive Connector

– Simulation Conclusions

– Summary• What data speeds would this simulation apply to.

• Who should be using this analytical/empirical approach.

Thursday, May 28, 2015 2015 Automotive Simulation World Congress 2


Automotive Cable & Connector Assembly

• Typical Structure of automotive Cable & Connector Assembly

– Twisted cable is connected to connector plug.

– R/A header pins connected to PCB.

– PCB designed for matched channel impedance.


Twisted cable

Plug

Crimp

Terminal

Pin

Header

PCB


HFSS Simulation for Automotive

Cable/Connector Assembly

Thursday, May 28, 2015

• Insertion loss (IL) is used to verify connector loss

budget.

• Return Loss (RL) is used to verify worst case reflection

as a function of frequency

• Sdc mode conversion quadrant defines possible EMI

issues, as a function of frequency.

• TDR defines worst case impedance changes in the

structure, (directly related to RL).

2015 Automotive Simulation World Congress 4


Typical mated connector model with integrated

PCB launch.

16.25mm

7.5mm

14.5mm


Typical Automotive terminal


Measurement vs Model Setup


Measured Setup Simulation Setup


HFSS Connector Setup/Simulation Results

Frequency Domain



HFSS simulation setup

• Typical setup

– Solution Frequency: typically 20GHz

– Max delta s: 0.01, to full convergence

– First order direct solver

– Interpolating sweep from 10 MHz to 20 GHz

– HFSS TDR – Rise time is based on highest sweep freq.

– 50 ohm wave ports used

– Boundary condition – air box



Insertion Loss: Simulation vs. Measurement


Insertion loss plots show reasonable correlation.

Red: Measurement

Brown: Simulation


Return Loss: Simulation vs. Measurement


Return loss plots show good correlation up to 1 GHz

Red: Measurement

Brown: Simulation


Mode Conversion (Sdc11)

Simulation vs. Measurement


Simulation and measurement plots have reasonable correlation

from 10 MHz to 1 GHz.

Dotted Red: 1Gbps MDI Limit

Red: Measurement

Brown: Simulation





Simulation and measurement results have 20 dB difference at 10 MHz,

gap reduces as frequency gets higher .


Red: Measurement

Brown: Simulation





Simulation and measurement have 15 dB difference at 10

MHz, the gap is reduced as frequency is getting higher.


Red: Measurement

Brown: Simulation





Simulation and measurement have 20 dB difference at 10 MHz, the gap is

reduced as frequency is getting higher.


Red: Measurement

Brown: Simulation


HFSS Connector Setup/Simulation Results

Time Domain



TDR (25 ps)



1. Capacitance between

antipad and via.

2. Inductance around the

connection pin in the

waterfall region.

3. Capacitance between

two crimps of terminals.

1

2

3

TDR with 25 ps filter is used to observe the impedance variation

of geometry.


Conclusions

• HFSS simulation results of high speed connector

shows good correlation in TDR, return loss, and

insertion loss.

• VNA mode conversion noise floor causes some

mismatch of mode conversion at frequencies below

10 MHz.



Summary

• This simulation can apply to data rates above 1GB/s with the following notations:

– Mode conversion correlation methodology needs further investigation

– Adding twisted wire for channel simulations will need further evaluation as to the correct modeling methodology

• This methodology is good to define:

– Connector design before production tooling

– PCB tuning and effects on the connector design



Thank You!


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