Re: [SI-LIST] : IBIS Model Verification

Stephen Peters (sjpeters@ichips.intel.com)
Wed, 09 Sep 1998 18:48:29 -0700

Hello Weston, others:

I might mention that the IBIS open forum has recognized this problem
of incomplete/messy models and has established an informal model review
program. It's basic purpose is to provide feedback to
the model creators on what they did or didn't do correctly. If you receive
an IBIS model that you think is in error and want to have it checked out
send it to Matthew Flora at mbflora@hyperlynx.com. Several EDA vendors that
support IBIS have volunteered to give submitted models the once over --
including running them with their simulators. (Obviously, if your model is
unreleased or otherwise confidential you will need to obtain the proper
NDAs...see Matthew for details).

I hope this helps.

Regards,
Stephen Peters
Intel Corp.
Vice Chair EIA-IBIS Open Forum

> Abe,
>
> Valid point! I am an IBIS consumer too. And I'm getting tired of
> messy, incomplete, and blatantly wrong IBIS files. I do the same as
> you. I run ibis_chk and then look at each VI and VT curve with
> ibisplot. About 90% of the files I receive require some fixing on my
> side. It appears that many people are creating IBIS files with very
> little understanding of the specification. Just because s2ibis ran
> without errors does not guarantee a good IBIS file! I think the best
> we can do right now is to tell the suppliers about the errors that we
> find in their files. Most of them want to learn how to do it right,
> and will gladly accept suggestions when presented tactfully.
>
> Here are some of the flags I look for:
> s2ibis 0.91BETA (!!! WARNING !!!)
> no Vmeas, Cref, Rref, or Vref
> clamp curves left in pullup and pulldown (s2ibis)
> pullup and pulldown curves not crossing 0,0
> 2 significant digits (s2ibis) causing stairstep curves
>
> I don't want to take away from the massive amount of work done in
> developing s2ibis. It can be a great tool if you know how to use it.
> Don't just run it without understanding what it does. I changed some
> things I didn't like in the code and use it internally when I have
> spice models.
>
> I was saying just yesterday that we need an ibis_fix program to look
> for the common errors and try to fix them. EDUCATION is the only real
> answer.
>
> Regards,
> Weston Beal
>
> > Thank you in advance for your response.
> >
> > Best Regards,
> >
> > Abe Riazi
> > SI Engineer
> > Anigma, Inc.

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