Re: [SI-LIST] : Best type of models, edge rates & load

D. C. Sessions (dc.sessions@vlsi.com)
Mon, 26 Jul 1999 13:02:45 -0700

Roy Leventhal wrote:

> So, what's your point about the 30% - 80% "transition time" convention where you
> correctly point out that it's less than half the output swing? I can dig out the
> data sheet and manufactuer's name for you if you wish. And yes, I think it's
> pure specsmanship and quite misleading. If you just skim over the data sheet
> numbers well, Caveat Emptor.
>
> But, I would guess that the 20% to 80% IBIS convention was chosen to fit in a
> more linear range of the I/O characteristics. I'm not sure that the choice has
> been a good one.

Good thing, then, that it's irrelevant.
"Rise time" no longer plays a meaningful role in IBIS modeling.
Put another way, if your analyses are actually sensitive to the
definition of "rise time" then you need to get better tools,
better models, or both.

-- 
D. C. Sessions
dc.sessions@vlsi.com

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