Post on 27-Apr-2020
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
High Speed and High Power
Connector Design Taiwan User Conference 2014
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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
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Typical Connector Design Workflow
Measurement Manufacture
Virtual Prototype Analysis
Optimization
Design
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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
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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
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Material Definition – Copper Alloy
* Data taken from First Copper Technology Co., LTD.
International Annealed Copper Standard (IACS)
Copper reference conductivity 58M S/m as 100%
27% IACS conductivity 15.66M S/m
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Material Definition - Substrate
* Data taken from VECTRA LCP material (E130i)
Dispersive material with Eps_r(f)
The dielectric dissipation factor or tangent of the loss
angle describes the losses
Higher order dispersion model
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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
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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
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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
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• Impedance profile in time
TDR (Time Domain
Reflectometry)
• Frequency domain
• IL and X-Talks
• SPICE Extraction S-Parameter
Connector Design Tools
What matter in connector design is “impedance”
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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
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TDR Response from Different Environment
Impedance overshoot Series L discontinuity
Impedance undershoot Shunt C discontinuity
Impedance overshoot & undershoot Combination L & C
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Excitation Signal
TDR
response
Step
function Gauss signal
Wideband spectrum
S-parameter results
Spectrum contains zero
amplitude
No meaningful s-parameter
)(
)()(
toi
toiZotZ
dttodtti
dttodttiZotZ
)()(
)()()(
Recommended excitation signal: Gauss signal
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TDR Resolution and Rise Time
Faster rise time includes higher frequency content
Higher frequency means smaller wavelength
Smaller wavelength leads to a better resolution of discontinuities
max
%90~10
876.0
ft rise
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TDR Response Different Rise Time
TDR response of 50–39–50 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
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Effect of Loss on TDR Response
Lossy medium:
attenuates the “spikes” and “dip” in TDR response
decreases the rise time degrades the TDR resolution
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TDR Cross Probing Z
(t)
Locating the discontinuity using the TDR Cross probing
Only available in time domain solver
Requires 3D time domain power flow result monitor
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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
Reconstruction of TDR response from return
loss (reflection coefficient)
S-Parameter
DUT 1 2
3 4
S21 S11
S31 S41
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S-Parameter Result
Typical S-Parameter results TDR response from the return
loss
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Connector Examples
DisplayPort
USB 3.0
High Speed Backplane Connector
Power Connector
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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
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PCB Test Fixture and Excitation Port
Waveguide port with differential
signal definition
Line impedance and differential
mode pattern are automatically
calculated
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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
Simulation Setting
Hexahedral mesh view in x-normal plane
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TDR Result (Open End)
h1>h2 higher parasitic inductance at
data line 1
h2
h1
Data line 1
Data line 2
Z(t
)
Time / ps
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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
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Z(t
)
Time / ps
TDR Result – Design Modification
Adding simplified plastic cover
at launcher
Add plastic cover at launcher helps to compensate the parasitic inductance
Introduces higher parasitic capacitance
Improve the TDR at the launcher (200ps-400ps)
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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
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Eye Diagram PRBS N=7
5Gbs data rate with trise=130ps
Good insertion loss and low cross talk level results in proper eye opening
eye width= 190ps
eye height= 0.94
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Example 2
USB 3.0 Standard A-Connector
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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 2.0
Differential
Signal Pair
(UTP)
GND
Power
GND
USB 3.0
Differential
Signal Pair (STP) USB 3.0
Differential
Signal Pair
(STP)
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3D Simulation Settings Differential mode
with 90ohm impedance
Simplified 3D
Cable Cross
section
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
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Cable Construction
Model of USB3.0 cable cross
section using CST CABLE STUDIO®
Low insertion loss at 2.5GHz for 3m long
USB 3.0 cable
3.3dB loss @ 2.5GHz
* Data taken from Universal Serial Bus 3.0 Specification
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Differential TDR mated connector
Z(t
)
Time / ns
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Differential insertion loss -7.5dB @2.5GHz for mated
cable assembly
Differential Insertion Loss
5.3dB loss @2.5GHz
Frequency / GHz
Mated connector
Output
Mated connector
Input
USB 3.0 cable
Circuit simulator CST DESIGN STUDIO™
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Differential NEXT Crosstalk between the USB 3.0
differential pairs
Differential Crosstalk
-45dB Xtalk @2.5GHz
Frequency / GHz
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Eye Diagram
minimum eye
height
minimum eye width
UI = 200ps 5Gbs data rate
Eye width and height are calculated from the center UI
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Example 3
High Speed Backplane Connector
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Backplane Connector
Up to 20Gbs data rate for each differential pair
Staggered pin configuration and edge-coupled design to achieve low loss and
low cross talk
Differential pair pin
assignments
Backplane side
Daughte
r card
sid
e
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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)
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Differential TDR TDR with 50ps (10%-90%) A
B
C D
E F
G H
I J
Modification of interior design to meet the TDR specification
Time/ns
Z(t
)
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Interior Modification
Time/ns
Z(t
)
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Differential Insertion Loss A
B
C D
E F
G H
I J
Losses for the selected pairs are within the limit <1dB for 6Gbs (3GHz) <2dB for 20Gbs (10GHz)
Frequency / GHz
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Crosstalk measurement always on daughter card side:
NEXT measurement: Signal injected on daughter card
side. NEXT <3.25% with 50ps (10%-90%)
Differential Crosstalk (NEXT)
NEXT 1
in NEXT 2
NE
XT
(%
)
Time/ns
Peak – Peak NEXT: 1.2%
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Differential Crosstalk (FEXT) in
FEXT 1
FEXT 2
FE
XT
(%
)
Time/ns
FEXT measurement: Signal injected on backplane side
FEXT <5.75% with 50ps (10%-90%)
Peak – Peak FEXT: 1%
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Worst Case Crosstalk
Cro
ssta
lk (
%)
Time/ns
Multi-pair-active crosstalk when the signal is injected from all
adjacent pairs. One victim pair and six aggressor pairs
Peak – Peak NEXT: 2.7%
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Eye Diagram PRBS N=7
eye width= 90ps
eye height= 0.9
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
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Example 4
Power Connector
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Multidisciplinary Approach Losses in material introduced
from HF EM-field
Losses in material introduced
from stationary or LF EM-field
Temperature increment as the result of losses
Increasing of temperature
leads to structure deformation
Structure deformation
detunes the HF-performance
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Simulation Setup 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
Input
6x 7.5A Output
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Simulation Workflow
Stationary current solver
Current distribution
Export thermal loss
Stationary thermal solver
Source: thermal loss
Temp. distribution
Heat flow
Structural mechanic solver
Source: temp. distr.
Deformation
original structure
deformed structure Automatic update all tasks!
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
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
Conclusions
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