RE: [SI-LIST] : Looking Inside IBIS Model

Abe Riazi (ariazi@anigma.com)
Wed, 19 May 1999 11:23:45 -0700

Mark Nass Wrote:

>> One thing I have always hated about IBIS models, at least the ones I have
>>received, that nobody has mentioned is that they usually do not contain
>>enough
>>of the Waveforms to generate a good QUAD model. I always get the message,
>>REVERTING
>>TO RAMPS. This gives a terrible QUAD model, and of no use.
>
>>Mark
>
>
Hi Mark:

I have converted some IBIS models using IBIS2XTK and have seen the
message:

REVERTING TO RAMPS, as you had mentioned.

There have been also some IBIS models that have yielded XTK models with
DEF_RISE and DEF_FALL curves. It depends on the type of test fixture
used by the model developer. Some test jigs are rejected by IBIS2XTK,
and hence the rise and fall waveforms of the IBIS model are considered
useless. When the test fixture (R_fixture, V_fixture, C_fixture, etc.)
parameters meet certain criteria acceptable by IBIS2XTK , then it
generates superior models with DEF_RISE and DEF_FALL sections.

Regards,

>Abe Riazi

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