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

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From: Kai Keskinen (keskinen@nortelnetworks.com)
Date: Tue Nov 28 2000 - 05:05:46 PST


Hi Erik:

I had been referring to both the field solver and the W-element model. The
response from Ted Mido of Avant! has answered most of my questions.

Thanks for all of the valuable responses.

Regards,

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

> -----Original Message-----
> From: Daniel, Erik S. [SMTP:Daniel.Erik@mayo.edu]
> Sent: Tuesday, November 28, 2000 7:57 AM
> To: Keskinen, Kai [KAN:0G15:EXCH]
> 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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