[SI-LIST] Re: ibis limitations
- From: Scott McMorrow <scott@xxxxxxxxxxxxx>
- To: chris.cheng@xxxxxxxxxxxx
- Date: Fri, 26 Jul 2002 17:04:23 -0700
Chris,
Who would beleive that we would ever agree?
Yes, Hspice does have issues with modeling loss, especially with lossy
materials like FR4. These can sometimes be resolved with w-element
table models, but the root cause is generally non-causality caused by
modeling dielectric loss and dielectric constant as fixed quantities.
There is a great deal of research in the area of dielectric modeling at
this time and much may come out of it. But at this time, the best
solution is use precise s-parameter measurements of the structures and a
methodology to simulate them. One is ADS, as you have mentioned.
Another is Nspice by Apache, which will support n-port s-parameters.
Another is Broadband Spice by Sigrity, which will convert n-port
s-parameters into a Spice black box. All will give exceedingly good
results and are well beyond the capabilities of any IBIS board level
simulator.
Best regards,
Scott
--
Scott McMorrow
Teraspeed Consulting Group LLC
2926 SE Yamhill St.
Portland, OR 97214
(503) 239-5536
http://www.teraspeed.com
Chris Cheng wrote:
>Well said Scott. And no one would probably image this come from Chris' mouth
>but even HSPICE seems to have significant problem modeling advanced
>packaging and long lossy interconnect with dielectric loss. A more advanced
>simulator like Agilent ADS seems to do the job better.
>Chris
>
> -----Original Message-----
>From: Scott McMorrow [mailto:scott@xxxxxxxxxxxxx]
>Sent: Friday, July 26, 2002 4:05 PM
>To: kalgudo@xxxxxxxxx
>Cc: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: ibis limitations
>
>
>Kal,
>
>An IBIS model will model a the driver characteristics of a 3 gig
>differential pair driver, if that driver is modeled well by the model
>supplier, if that driver does not have preemphesis, and if that model
>does not have a package.
>
>IBIS cannot currently handle drivers with preemphesis and is very poor
>at modeling packages. You will have significant divergence from reality
>if you use an IBIS package model in a 3 gig differential simulation.
>
>The solutions is generally to use Spice to model your 3 Gig devices.
>
>Regards,
>
>Scott
>
>
>
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