[SI-LIST] : Ibis models

Jim Freeman ([email protected])
Fri, 24 Sep 1999 10:53:11 -0700

Hi all,
I have been working on generating IBIS models from the Hspice
description of an output buffer. I have the NCSU freeware and have used
it to generate the Hspice runs and the resultant IBIS model. when I run
the models thru the ibis check utility, it finds non-monotonic results
in the Pulldown,Pullup,and clamp curves. The rising and Falling waveform
have no problem. The IBIS check utility only issues a warning which
indicates to me that IBIS 2.1 models are not required to be exactly
monotonic. These ibis models as so generated are taken by both the
ibis2xtk utility and the ibis2signoise utility and generate acceptable
models to both of these simulators. In the Cadence info for the 2.1 GUI
that they provide, it is stated that most simulators perform smoothing
functions on the IBIS models before they use them.
question: Are IBIS models usable and/or acceptable with these
non-monotonic values which are occurring at about a diode drop below the
gnd rail and a diode drop above the power rail.

Jim Freeman

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