Re: BIRD42 Modeling Current Waveforms

Hi Scott, IBIS

At 07:16 PM 5/16/97 PDT, you wrote:
>It is not sufficient to model only the effects of output switching
>on package currents.
>....
>Anything less ain't even close, leading to gross underpredictions
>of the power transient currents on boards and devices.
>Scott McMorrow
>Stramond Corporation

  You make a valid point that IBIS can be improved to include internal
effects of devices
during switching intervals to better predict power transients. However to
say "that anything
else is not close" or that these effects "must be modeled" is at the very
least quite ridiculous.
There are numerous types of simulations using IBIS models e.g. analysis of
transmission line
effects in propagating signals which was the original goal of IBIS. To say
that IBIS is not
acceptable in general because it is not perfect for some devices at doing
power transient
analysis is simply not true. Additionally there are numerous classes of
components for which
modeling the output buffers does give a very good indication of the power
transients.
Obviously as the internal complexity increase relative to the current
switching magnitude of
the outputs the accuracy decreases as you correctly pointed out.

Perhaps I am taking your statement out of context. If so would you
consider being more
specific about the context you had in mind for your comments. For example
if you intended
your comments to reflect only modeling power transients I would prefer that
you preface
your opening with such.

Kellee

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Have a great day...
Kellee Crisafulli at HyperLynx Inc.
kellee@hyperlynx.com http://www.hyperlynx.com
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Received on Sun May 18 09:33:29 1997