removing non-monotonic points?!


Subject: removing non-monotonic points?!
From: Mohan, Prabhu (Prabhu.Mohan@actel.com)
Date: Wed Feb 06 2002 - 18:59:26 PST


Hi all,

I have a few questions regarding a paper that was presented at the last IBIS
Summit, that suggested various methods to remove non-monotonic points from
the IBIS model file.

http://www.eda.org/pub/ibis/summits/jan02/bell2.pdf

For example, on page11, the pulldown curve is just extrapolated in the -ve
region to remove non-monotonic behavior.

Question#1: Won't we double count the clamp current by doing this (since
simulation tools add the Pulldown/up curves with the clamp curves)?

Question#2: What do we do if the silicon really does behave like this? (true
in my case. i do get a similar -ve bump when i subtract the 'tristate' curve
from the 'ouput low' curve)

Question#3: Is it advisable to remove the non-monotonic points completely,
since they almost always seem to occur outside the normal operating range?
ie. flatten the -ve/+ve bumps?

There might not be a simple solution. But I'd really like to know what the
possibilities are.

Thanks in advance,
Prabhu/~



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