Subject: Re: Initial Help

From: [email-masked]
Date: Mon, 13 Mar 2000 07:59:46 -0600

As an IBIS user and developer, I would strongly recommend

1) correlating IBIS-based behavioral simulations with HSPICE simulations
for a given set of test circuits, and
2) correlating HSPICE simulations with hardware.

There are some I/O circuit designs whose electrical behavior s2ibis2 will
miss.  Here's a list of things that you should watch out for:  multi-stage
drivers, dynamic clamping, dynamic impedance or edge rate control, any kind
of feedback, and stored charge effects.  Some of these things are covered
by IBIS 3.2, and some of them are not.  Sometimes you'll also find things
in hardware that aren't in your HSPICE model, for various reasons.

Item one above will be easier to accomplish than item two, which involves
adding some extra circuitry to your component characterization test bed.  A
few years ago a group of IBIS users got together and tried to spec some of
these things.  Have a look at the IBIS web page under "accuracy," and
you'll find a document that addresses the topic of correlation.  It's not
any official spec, but it does have some pretty helpful background
information.  I'd also strongly recommend documenting your correlation
results in a format that your users can quickly digest.

Speaking from experience, a behavioral model can seem simple at first
glance.  You may actually get IBIS code from s2ibis2 in less than a day.
However, there can be many little gotchas that you won't find until you do
the correlation work.

Greg Edlund
Advisory Engineer, Critical Net Analysis
IBM
3650 Hwy. 52 N, Dept. HDC
Rochester, MN 55901
[email-masked]

Gaurang Shah <[email-masked]> on 03/12/2000 02:32:15 PM

To:   [email-masked]
cc:   [email-masked]
Subject:  Initial Help

Hello,

I am currently initiating IBIS model development here and I need a couple
of clarifications.

1) Which version of model should I be developing?? Seems like Version 2.1
seems to be the most commonly used models. Are most people developing in
2.1 or customers demand version 3.1 and higher?

2) I plan to use the SPICE2IBIS utility, but it appears that shareware from
North Carolina State  University generate 2.1 models only. Are there free
tools available for higher version models or does one have to buy
commercial tools?? If latter is the case what is the cost of them and who
are the vendors??

Please help.

--Thanks

--Gaurang