Subject: Re: BIRD #61

From: "Matthew Flora" <[email-masked]>
Date: Thu, 2 Sep 1999 09:02:29 -0700

Arpad,

> If we go with functions to characterize input behavior, the model maker
> will have to generate the coefficients, or even the function itself.  In
> this case the simulator may turn into a dumb number cruncher.

Personally, I have no problem with turning the simulator into a dumb number
cruncher.  There would still be plenty of ways to differentiate tools (speed,
price, usability, completeness, platform support, etc., etc.)

I assume that the model maker is the most informed of anyone on the actual
behavior of the component.  Therefore, I would further assume that an equation
generated by the model maker would be more accurate than a generic equation
fitted by an EDA tool.

I realize this increases the burden on the model maker, but hopefully the same
equation would be applicable to a whole family of parts (with perhaps minor
modifications for each part).  If this were true then the "cost" of developing
the base equation could be amortized across the whole part family.

(I also realize that adding support for equations to IBIS could be a large
undertaking.)

I myself have no experience with equation based models, so I don't have a feel
for their impact on simulation times relative to table driven simulation, nor
do I have a feel for the odds of equations being incorrect or incomplete.
However, I am optimistic that adding equations to IBIS might stem the growth
of IBIS into an ever more complicated standard that only an "expert" can use.

Regards,
Matthew Flora
IBIS Open Forum Postmaster
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