RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines

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From: David Kaiser (david.kaiser@mcdata.com)
Date: Tue Nov 28 2000 - 08:26:49 PST


I was referring to the accuracy of "PETL", the internal HSPICE field solver
seeming to be limited above 1GHz.
 
David Kaiser
McDATA Corp.
310 Interlocken Pkwy.
Broomfield, CO 80021
(303) 460-4431
davidk@mcdata.com

-----Original Message-----
From: Daniel, Erik S. [mailto:Daniel.Erik@mayo.edu]
Sent: Tuesday, November 28, 2000 5:57 AM
To: keskinen@nortelnetworks.com
Cc: si-list@silab.eng.sun.com
Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines

Kai-
 
Are you referring to the accuracy of the internal HSPICE field solver that
can compute the RLCG elements for certain geometries, or the transient
simulation framework that takes the RLCG matrices and acts as the "element"
in the circuit? Or both?
 
We use external tools to compute RLCG matrices, then using these as input to
the W-element "framework" mentioned above. Generally we have had good luck
(e.g., reasonable simulated results with reasonable match to experiment),
but we have found a few regions of input phase space that lead to erroneous
(and sometimes even laughable) results. We have been unable to pin Avant!
down as to exactly what range of inputs yields acceptable output -- it could
be that they don't really know. The worst problems we have seen are when
the losses (e.g., R components) become large.
 
Also, we have noticed that the default dispersion relations for R, L, C, and
G are somewhat limiting (although I have not tried the new version which
presumably supports arbitrary frequency dependent R, L, C, and G).
 
                    - Erik

==================================================================
Erik Daniel, Ph.D. Mayo Foundation
Voice: (507) 284-1634 Guggenheim 1011B
Fax: (507) 284-9171 200 First Street SW
E-mail: daniel.erik@mayo.edu Rochester, MN 55905
==================================================================

-----Original Message-----
From: Kai Keskinen [mailto:keskinen@nortelnetworks.com]
Sent: Thursday, November 23, 2000 12:19 PM
To: si-list@silab.eng.sun.com
Subject: [SI-LIST] : Accuracy of HSPICE W-element transmission lines

Hello SI-People:

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
W-element model?

Thanks in advance,

Kai Keskinen
Equipment and Network Interconnect
Nortel Subsystems and Performance Networks (NSPaN)
(613)-765-3506 (ESN 395)
keskinen@nortelnetworks.com

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