Re: Quest for IBIS models

Greg,

IBIS is *information* not a model. If there is such a thing as an IBIS model I
would guess that it is a SPICE behavioral model that uses IBIS data in Piece-Wise
Linear voltage or current sources.

I have seen a document describing a methodology for converting IBIS data into a
SPICE behavioral model. It was generated by Intel and the copy I saw was marked
confidential. Maybe Will or someone at Intel can tell you how to get a copy.
Frankly, I'm surprised that it is not in pub/ibis/documents on vhdl.org.

The IBIS/SPICE behavioral model has the same advantages that any SPICE behavioral
model has over a transistor-level SPICE model, ie. it is faster and gives you
fewer convergence problems.

I've seen IBIS data from Intel, and Motorola. TriQuint has data in their databook
that looks like IBIS data to me.

Almost everyone will give you SPICE models if you keep after them. TI, LSI, and
IDT are great about providing SPICE models. DRAM companies like Micron, Motorola,
and Hitachi will give you SPICE models, but unfortunately, they don't provide the
all important clamp (protection) diodes in their models. I'm sure I've left out
some very important companies who provide SPICE models and I apologize for my
lapse of memory.

With the SPICE model, you can create your own IBIS data and from that, create your
own SPICE behavioral model.

I think maybe you are looking for a simulation tool that ingests IBIS data and can
be used for simulation and analysis. I'm sure you will hear from many of them. I
understand that Quad Design (XTK/TLC) and MetaSoftware (HSPICE) are planning to
release something like that. I would bet that every EDA company on the IBIS roster
has similar plans.

Until the EDA IBIS tools are all available I would suggest that you try using IBIS
SPICE models generated from SPICE models. This should not be a threat to the EDA
companies. In fact, I believe it is a healthy exercise to create SPICE IBIS
behavioral models. It will give you a better understanding of the entire process
and maybe some of the advantages and pitfalls of IBIS data. I am sure that it will
also give you a great appreciation of the various tools that use IBIS data when
they are available.

If you have a question about a specific SPICE or IBIS model that you are looking
for let me know what it is off-line, and I'll see if I can help you with it.

Regards,
Fred
FirePower Systems, Inc.

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Date: Thu, 9 Feb 95 12:50:16 -0600
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To: ibis@vhdl.org
From: gre@scintl.com (Greg Edlund)
Subject: Quest for IBIS models

I took a peek into /pub/ibis/models the other day and found only
a small collection of models for Intel's CPUs and chip sets.
Am I correct in assuming that in order to procure IBIS models
for the parts on my board design, I will either have to

a. go to the mfgr's rep, or
b. buy a library from someone like Zeelan?

Have any of you found manufacturers yet who know what IBIS models
are? I'm having a hard time trying to explain what SPICE models
are, much less get them in my greedy hands. And SPICE has been
around a LONG time. I'm just wondering how far we are along the
road toward creating an information exchange which is beneficial
to the engineer and does not give the manufacturer a migraine
and/or keep their lawyers up at night.

Thanks in advance.

--
Greg Edlund                +----+----+    "Years ago my mother would say to me,
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