RE: [SI-LIST] : Ibis models

Abe Riazi (ariazi@anigma.com)
Sat, 25 Sep 1999 15:01:28 -0700

Jim Freeman Wrote:

>> 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.
>
>
Hi Jim:

Based on experience with IBIS and XTK models, I agree with above
statements. The I-V sections of an IBIS model include:

pullup
pulldown
GND_clamp
POWER_ clamp

The corresponding I-V curves of XTK models consist of:

HIGH
LOW
SHUNT
SHUNTP

The IBIS format does not require monotonicity for the I-V tables.
However, the XTK simulator demands that the I-V curves of the Quad
models to be monotonic. When translating an IBIS model having
non-monotonic I-V data, IBIS2XTK shifts the currents between the LOW/
HIGH state curves and SHUNT/ SHUNTP curves (or deletes some points if
necessary) towards generating monotonic curves.

While I have seen numerous IBIS models having non-monotonic I-V data,
I have not noticed any XTK models with non-monotonic I-V curves.

Regards,

Abe
ariazi@anigma.com
>
>

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