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

About this list Date view Thread view Subject view Author view

From: Daniel, Erik S. ([email protected])
Date: Tue Nov 28 2000 - 04:57:23 PST

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: [email protected] Rochester, MN 55905

-----Original Message-----
From: Kai Keskinen [mailto:[email protected]]
Sent: Thursday, November 23, 2000 12:19 PM
To: [email protected]
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)
[email protected]

**** To unsubscribe from si-list or si-list-digest: send e-mail to
[email protected] In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at

About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Tue May 08 2001 - 14:30:16 PDT