Subject: s2ibis2 issues

From: Mike LaBonte <[email-masked]>
Date: Fri, 12 Jan 2001 18:55:26 -0500

Hello,

One would think I would know the answers by now, but...

1) Has anyone used s2ibis2 to convert 1.5V logic? I had to fix it
   because it was putting bogus points near the ends of thepullup
   and pulldown VI curves.

2) Why does s2ibis2 run waveform simulations with 100 points,
   then resample them down to 51 points for output to the IBIS
   file, when the IBIS spec allows 100 points? The resampled
   waveform even has a time lag with respect to the original.

Since s2ibis2 has been used to create many IBIS models since it
was last updated in August 1998, one would assume that it is
producing fairly good results, once one learns to use it. But I
find these issues and others, too. Has every working copy out
there been modified like mine?

Mike LaBonte

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From: Al Davis <[email-masked]>
Date: Fri, 12 Jan 2001 16:22:53 -0800

>    waveform even has a time lag with respect to the original.

Here's my guess:

They were planning to add an algorithm to do smart point selection, 
but the student graduated and no-one else picked up the work.

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From: Scott McMorrow <[email-masked]>
Date: Fri, 12 Jan 2001 19:29:25 -0800

Mike,

1) Yes, it puts in bogus points.  We just delete them.

2) Good question.  I modified the code to simulate
with 250 points.  This is available in s2ibis2fix.
We resample down to 100 points with an external
algorithm.

3) We also modified the code to run on Windows NT
and 2000 with HSpice, and increased the number of
significant digits being printed in the tables, also.

Welcome to the club.

regards,

scott

--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR  97062-3090
(503) 885-1231
http://www.siqual.com