2. SYNERGIE CAD
Confidential
Page 2
Design Engineering
Simulation Overview - Tool Set
• ANSYS HFSS software is the industry-standard simulation tool for 3-D full-wave electromagnetic field
simulation and is essential for the design of high-frequency and high-speed circuit design.
– Provides accuracy for the design of high-speed circuits, test sockets, PCB interconnects, high-
frequency components and RF/microwave components.
– Evaluate signal quality, including transmission path losses, reflection losses due to impedance
mismatches, parasitic coupling and radiation.
– Visualize 3-D electromagnetic fields.
• ANSYS SIWave to analyse complete designs (includes multiple, arbitrarily shaped power/ground
layers, vias, signal traces and circuit elements).
– Perform complete signal-integrity and power-integrity analysis from DC to beyond 10 GHz.
• Extract matrix parameters (S,Y, Z parameters), of signal nets and power distribution networks directly
from EDA layout databases*.
• Aids in the identification of signal-integrity and power-integrity problems and is critical to first-pass
system success.
* ODB++ is used as a common transfer method. It must be verified if the ODB++ file created by a
particular package is compatible.
3. SYNERGIE CAD
Confidential
Page 3
Simulation
EDA Data Import
• ODB++ data files from the EDA Layout tool are directly imported.
– Synergie-Cad can also provide simulation as a separate service.
• Measurement ports are place at the required points on the layout
• Extraction of matrix parameters (S,Y, Z parameters) for analysis.
• Cut-out sections of the layout to perform detailed 3D full-wave simulation of
High-frequency and RF/microwave areas.
Verigy 93K 9.5”, Vertical Probe Card, 32 Layer
4. SYNERGIE CAD
Confidential
Page 4
Simulation - Signal Integrity
Matrix Data (S,Y,Z, Parameters) Analysis
Transmission and Return Loss Signal Isolation
RF, Inductance and
Capacitance Measurements
RF, Impedance, VSWR, Matching
5. SYNERGIE CAD
Confidential
Page 5
Simulation - Signal Integrity
TDR Analysis
Open circuit seen:
~7ns / 2 (return time of signal path) = ~3ns
Disturbance from Components
Tester pogo, t = 0ns
7. SYNERGIE CAD
Confidential
Page 7
Example Simulation - Signal Integrity
Optimised Tapered RF Transformation
Optimised RF tapered transmission line
impedance transformation, wideband, up to
30GHz.
8. SYNERGIE CAD
Confidential
Page 8
Simulation – Usage Scenario #1
• Simulate the performance of standard cantilever needle at
RF frequencies.
• The complete needle assembly, epoxy ring and PCB is
included in the model.
Port 1 (S1)
Needle Tip
Port 2 (S2)
PCB launch track
Simulation results.
Freq. sweep: 1GHz to 10Ghz.
9. SYNERGIE CAD
Confidential
Page 9
Simulation – Usage Scenario #2
• Model of the needle assembly used to understand the inductance of a
cantilever needle at ~920MHz.
• S-Parameters simulated for S11, S22.
10. SYNERGIE CAD
Confidential
Page 10
• BGA devices often require, micro vias to allow routing from pads on internal
rows.
• In the cases where high speed signal pads are located on internal rows of
the BGA, PCB traces must use a micro via to an internal layer.
• Simulation used to help optimise the via performance.
• Detailed simulation can be performed on the final design data, as shown on
previous slides.
Field strength
around the via.
Transmission and return loss performance
Laser via model.
Simulation – Usage Scenario #3
12. SYNERGIE CAD
Confidential
Page 12
Simulation – Usage Scenario #4
• Possible to simulate and include as part of a
larger simulation the performance of springs
pins from a socket body or vertical probe head.
0
1
2
3
4
5
0 1 2 3 4 5 6 7
Frequency (GHz)
Inductance(nH)
-3
-2
-1
0
0 1 2 3 4 5 6 7
Frequency (GHz)
InsertionLossS21(dB)
-60
-50
-40
-30
-20
-10
0
0 1 2 3 4 5 6 7
Frequency (GHz)
ReturnLossS11(dB)
Fig.1 Inductance
Fig.2 Insertion Loss Fig.3 Insertion Loss
13. SYNERGIE CAD
Confidential
Page 13
Simulation – Usage Scenario #5
• Multiple ports can be used (limited by physical RAM).
• A differential 4 port structure; Allows mutual coupling effects
to be included in the S-Parameter model.
Port 4
Port 2
Port 3
Port 1
14. SYNERGIE CAD
Confidential
Page 14
Simulation – Exported Data
• S-Parameter data file can be provided to customers, to allow in
circuit simulation of the PCB before it is manufactured.
• Allows for confidence in the PCB layout and design before
committing to the manufacture.
• Can save time and cost, if in the unlikely event a problem is found
on the PCB after manufacture during functional test.
! Touchstone file from project RF-probe
! Exported from HFSS 12.0.0
# GHZ S DB R 50.000000
! Modal data exported
! Port[1] = 1:1
! Port[2] = 2:1
1.000000000000000E+000 -1.591625431137832E+001 6.038651181469610E+001 -1.717771359540705E-001 1.574416881357343E+002 -1.717771359776334E-001 1.574416881357361E+002 -1.591195795430505E+001
7.239763240570214E+001
! Gamma ! 3.208151732005790E-001 3.325143588579720E+001 5.466199417260070E-001 2.153677718539890E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.020000000000000E+000 -1.576155621619889E+001 5.985904360802454E+001 -1.766716037997347E-001 1.570001641968290E+002 -1.766716038225167E-001 1.570001641968333E+002 -1.575655129063723E+001
7.207979692165326E+001
! Gamma ! 3.255003515711610E-001 3.391460264595060E+001 5.522104634251370E-001 2.196188115903890E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.040000000000000E+000 -1.561036871747129E+001 5.933085863626302E+001 -1.816183221631865E-001 1.565590161471024E+002 -1.816183221760694E-001 1.565590161471050E+002 -1.560465439970176E+001
7.176258651197038E+001
! Gamma ! 3.301673057542710E-001 3.457775255480910E+001 5.577466864496830E-001 2.238693032252120E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.060000000000000E+000 -1.546256739218918E+001 5.880199511398957E+001 -1.866161704299441E-001 1.561182461765168E+002 -1.866161704158439E-001 1.561182461765162E+002 -1.545614286407101E+001
7.144601059557014E+001
! Gamma ! 3.348165516777520E-001 3.524088620358890E+001 5.632302265895430E-001 2.281192631963770E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.080000000000000E+000 -1.531803494120466E+001 5.827248792205044E+001 -1.916640036873145E-001 1.556778563474119E+002 -1.916640036891304E-001 1.556778563474121E+002 -1.531089896310634E+001
7.113007977290391E+001
! Gamma ! 3.394485815203670E-001 3.590400416555220E+001 5.686625484260600E-001 2.323687063456820E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.100000000000000E+000 -1.517666038426494E+001 5.774236919951760E+001 -1.967606620369866E-001 1.552378485811792E+002 -1.967606620519684E-001 1.552378485811796E+002 -1.516881142000810E+001
7.081480431003746E+001
! Gamma ! 3.440638652636880E-001 3.656710698309110E+001 5.740450196510690E-001 2.366176480297920E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
1.120000000000000E+000 -1.503833869203307E+001 5.721166700504775E+001 -2.019049684669666E-001 1.547982247028583E+002 -2.019049684601701E-001 1.547982247028581E+002 -1.502977500566388E+001
7.050019583243576E+001
! Gamma ! 3.486628520458660E-001 3.723019517758280E+001 5.793790270819260E-001 2.408661001759890E+001
! Port Impedance 5.000000000000000E+001 0.000000000000000E+000 5.000000000000000E+001 0.000000000000000E+000
15. SYNERGIE CAD
Confidential
Page 15
Signal Integrity Applications using S-Parameters
– Single port
• Measure impedance
• Model interconnections
• Smith charts – measure complex impedance by frequency.
– Two port
• Return loss - losses due mismatches
• Transmission line impedance, electrical length, losses.
• Cross talk at any frequency.
– Four ports, multiple ports
• Complete coupled line characterisation, single ended, differential,
return losses, transmission losses, impedance, electrical length.
16. SYNERGIE CAD
Confidential
Page 16
Simulation - Power Integrity
Basic Requirement: Target Impedance
• The Impedance looking in the DPS from the device should be kept low over
a broad frequency range.
• The Desired Frequency Range and Impedance Value is referred to as the
Target Impedance.
DUTDPS
I
V Z
17. SYNERGIE CAD
Confidential
Page 17
Simulation - Power Integrity
• Selecting the correct capacitance values is critical.
• Capacitors selection from a library of capacitor models.
• S-Parameter models can also be used.
18. SYNERGIE CAD
Confidential
Page 18
Simulation - Power Integrity
• However.. calculation of values alone is not enough.
• The effects of the layout must be taken into account.
Calculated
Simulated
19. SYNERGIE CAD
Confidential
Page 19
Simulation - Power Integrity
Analysis of Complete PCB Model
• Library of S-Parameter models for capacitor and inductors.
• Passives are fitted and at the SMD pads
• Entire PCB layout including passive is simulated.
• Simulated Matrix Data (S,Y,Z, Parameters) output.
20. SYNERGIE CAD
Confidential
Page 20
Simulation - Power Integrity
Placement effect on Target Impedance
1KHz 1MHz 100MHz GHz
Bulk
Capacitors
Ceramic
Capacitors
Planes
• The effect of the placement and layout must be included in the overall
model.
• Optimisation of the placement of components is required to minimise plane
resonances.
• Optimisation of capacitor type / placement for the required performance
over the desired frequency range.
• Optimisation of the layout to improve performance.
– Inductance loops
– Via length
– Plane impedance
21. SYNERGIE CAD
Confidential
Page 21
Example Simulation - Power Integrity
Resultant Matrix Data (S,Y,Z, Parameters)
Impedance of power plane only with no decoupling
Power impedance with decoupling included
22. SYNERGIE CAD
Confidential
Page 22
Simulation - Power Integrity
Effect of Decoupling Network on Voltage Drop @
DUT
• Transient simulation to verify the effectives of the decoupling
network.
• Circuit simulation of power supply using extracted board S-
Parameters and decoupling.
• Cascade S-Parameter blocks to include any bulk decoupling of WPI
and PC, for example.
Power supply model
DUT current load
23. SYNERGIE CAD
Confidential
Page 23
Simulation - Power Integrity
Effect of Decoupling Network on Voltage Drop @ DUT (cont.)
• Transient simulation to verify the effectives of the decoupling
network.
• Power supply models of the tester hardware provided by the tester
manufacturer.
• Simulate and verify the effects of a current transient on the overall
network.