Re: [SI-LIST] : SI analysis: IBIS vs. HSpice

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From: Scott McMorrow (scott@vasthorizons.com)
Date: Fri Jan 19 2001 - 09:24:16 PST


Pat,

Version 3.2 is actually a fairly old and mature spec. There are
a number of simulator vendors that comply with most of the spec. I agree
with you that the package specification does not cover all modeling
issues adequately. However, there is an IBIS connector model
specification in committee that should resolve most issues which you
have. Although it was designed for connectors, the same principles
apply for packages, also.

Information on the work of the committee can be found here:

 http://www.eda.org/pub/ibis/connector

The most recent revision of the proposed specification can be found here:

 http://www.eda.org/pub/ibis/connector/IbisConnectorSpecV0955.doc

There will also be a presentation at the IBIS Forum on Monday
of DesignCon at the end of the month.

regards,

scott

"Zabinski, Patrick J." wrote:

> Jim,
>
> Until now, I had not seen IBIS 3.2. I gave it a quick scan (particularly
> section 7), and it looks like the standard (at least) has made
> some significant improvements in the package description of
> the model. Not sure who out there is responsible, but THANKS for
> upgrading/updating the spec, and sorry if I offended anyone out there.
>
> Now that the standard has been improved, have you seen
> any evidence that the vendors/suppliers have been utilizing
> this feature? If so, again THANKS to them.
>
> All that said, the package model portion is still only a "portion"
> of what I consider to be several shortcomings in the IBIS model
> content, and as such, I much prefer to use transistor-level models
> whenever possible.
>
> Pat
>
> >
> > Hi Pat,
> >
> > I agree with many, if not all, at least to some degree, of your points
> > regarding IBIS.
> >
> > However, in particular I wanted to address your concern about package
> > parasitics. This is a timely topic as I was going through,
> > in excruciating
> > detail, the "Package Modeling" section of the IBIS 3.2 spec
> > yesterday. I'm
> > wondering if you've had the opportunity to review this
> > addition to IBIS.
> >
> > It seems to me that it may address at least some of your
> > concerns. It seems
> > to provide an implementation somewhat along the lines of a
> > TOPSPEC type
> > model in XTK (if your familiar with that). It provides the
> > capability to
> > specify transmission line length, coupling between pins,
> > forking sections,
> > etc.
> >
> > You can provide RLC matrices in full, banded, or sparse formats.
> >
> > This is a somewhat new area for me, so I'm by no means
> > proclaiming this a
> > panacea for the issues you describe, but if you have an opportunity to
> > review that portion of the IBIS 3.2 spec (the package model
> > stuff is in
> > Section 7) I'd be curious to get your thoughts on how well this might
> > address your concerns on the package parasitic issues.
> >
> > Now, of course assuming this is an improvement, the challenge
> > still lies in
> > getting semiconductor folks to provide that level of detail (perhaps
> > non-trivial for a 300, 400 or greater pin part?) and then
> > getting all the
> > various simulators to use the data in an intelligent manner.
> >
> > Again, I agree with your concerns on IBIS shortcomings
> > (especially with
> > respect to SSO phenomena). However, I guess I have an
> > interest in hoping
> > that it continues to improve because in many cases HSPICE (or
> > any transistor
> > level data) is simply not an option provided to us by many
> > (actually, most)
> > vendors.
> >
> > I'd be curious to get anybody's feedback on the shortcomings
> > or strengths of
> > the IBIS 3.2 package modeling capabilities.
> >
> > Regards,
> >
> > Jim P.
> >
>
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--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR  97062-3090
(503) 885-1231
http://www.siqual.com

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