From: Haller, Robert ([email protected])
Date: Tue Nov 28 2000 - 14:12:16 PST
A while ago I did simulation versus measurement comparisons using AVANT!
and a TDR with high bandwidth FET probes.
(But I used RLGC matrixes generated by Digital's/Compaq's internal Field
solver - SIMPEST) .
I utilized various edge rates 50->500 ps edge rate, a 12 inch transmission
line, and Hspice 99.x
I also acquired and digitized the source and destination waveforms of the
was careful to model the probes in my simulation and use the actual
digitized waveform (PWL)
with the correct output impedance as the input stimulus to SPICE.
A few Key items was to digitize the input waveform going into the W-line and
to Cross-section the
actual Transmission Line you measured.
I was successful in getting W-line simulations to virtually overlay measured
results (far end
of the Transmission line using the W-LINE).
At higher edge rates (< 100ps) we began to see discrepancies. I think these
were limitations in the
Dielectric losses not modeled over frequency, Michael Tsuk, Could answer
I also found the the simulations were surprising affected be HSPICE OPTIONS;
Very Long Lines (> 3 Meters had issues - I think this has been fixed)
T-lines were surprising good if you don't care about high frequency effects
and U-Lines were horrible.
From: Larry Miller [mailto:[email protected]]
Sent: Monday, November 27, 2000 1:53 PM
To: David Kaiser; Kai Keskinen; [email protected]
Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines
Yes, but have you compared your results (either) with real hardware?
Inquiring minds want to know....
From: David Kaiser [SMTP:[email protected]]
Sent: Monday, November 27, 2000 10:17 AM
To: Keskinen, Kai [KAN:0G15:EXCH]; [email protected]
Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
I have compared the W-element with the RLGC matrix from running
APSIM on 100 Ohm diff'l pairs). With a 30ps pulse and 10ps rise times, the
reflected pulse was very symetrical for the W-element, but showed and RC
roll off with APSIM. The APSIM seemed to shown a more realistic reflection
310 Interlocken Pkwy.
Broomfield, CO 80021
From: Kai Keskinen [ mailto:[email protected]
<mailto:[email protected]> ]
Sent: Thursday, November 23, 2000 11:19 AM
To: [email protected]
Subject: [SI-LIST] : Accuracy of HSPICE W-element transmission lines
We have now several times encountered differences in results from
other modelling packages and results from HSPICE w-element models for
applications involving fairly long striplines > 30cm on FR4 and GETEK with
2.5Gbps signals with ~100ps edge rates. The W-element model appears to give
lower loss than the other techniques. Typical track widths are 6-8 mils with
100Ohm loosely coupled differential pairs.
Avant! claims the W-element method is accurate without providing a
paper showing how it was validated.
How does the rest of the SI community feel about the accuracy of the
Thanks in advance,
Equipment and Network Interconnect
Nortel Subsystems and Performance Networks (NSPaN)
(613)-765-3506 (ESN 395)
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