RE: [IBIS] Subtracting "Lead-in" Offset from V-t curves

You have to strip the same amount of time from all waveforms. The purpose
of the multiple VT waveforms is to show how one device turns on and the
other device turns off. If you start moving the waveforms around then you
could have situations where both the pullup and pulldown device are on at
the same time or neither device is on during the transition. Some
simulators flag this kind of condition and generate errors for the model.
The IBIS parser does not check for this conditions

Tom Dagostino
Teraspeed Consulting Group LLC
503-430-1065
tom@teraspeed.com
www.teraspeed.com

-----Original Message-----
From: owner-ibis@eda.org [mailto:owner-ibis@eda.org]On Behalf Of David
Mahashin
Sent: Wednesday, December 22, 2004 9:36 AM
To: ibis@eda.org
Subject: [IBIS] Subtracting "Lead-in" Offset from V-t curves

Hi,

I have a question concerning the offset on V-t curves. I realize that most
simulators (e.g. Hyperlynx) have the option of automatically stripping the
"lead-in" offset.

However, if I do want to subtract the offset manually, is it necessary to
subtract the same offset amount to all of the rising/falling waveform
tables?

What is the effect of subtracting different offset amounts such that all the
waveforms rise/fall at the same point in time? Will this incorrectly model
the input to output delay of the buffer?

Thanks,

David

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Received on Wed Dec 22 10:22:40 2004