Re: [SI-LIST] : IBIS Subcommittee Formed to Review Spice to IBIS

Bob Ross (bob_ross@mentorg.com)
Tue, 08 Jun 1999 11:44:06 -0700

To All:

We the 100 point VT limit up at the last IBIS Meeting based on the fact
that several people felt that accuracy could be compromised. The general
consensus was to consider a conservative 1000(1) point limit for a future
Version of IBIS. An expanded discussion is in the minutes stored at

http://www.eda.org/pub/ibis/minutes/min1999/m052899.txt

I think we should consider more flexability regarding the number of
points (including going beyond the limit) in the upgraded s2ibis2/3
utility.

Bob Ross
Mentor Graphics

jonp@pacbell.net wrote:
>
> I agree with Weston.
>
> Either that or remove the quite artificial limit of number of points in an IBIS
> file.
> I have actually been faced with the problem that even with software to remove
> extra points I cannot
> create IBIS models to the accuracy that I desire with the 100 point limitation.
>
> jon powell
> Viewlogic Consulting Services
>
> Beal, Weston wrote:
>
> > Kellee,
> >
> > You're disagreeing a mute point. Your point was the same point I was trying
> > to state by saying, "the IBIS creator tool should have an algorithm to
> > remove points in linear regions." We should delete all these extra data
> > points. The problem that s2ibis has now is that all points are equal
> > difference. They should be closer in knee points and very sparse is linear
> > regions. The IBIS creator tool should have an algorithm to clean out extra
> > data.
> >
> > So, I agree with you and now you can agree with me.
> >
> > Later,
> > Weston Beal
> > Signal Integrity Engineer
> > Compaq Computer Corp.
> >
> > -----Original Message-----
> > From: Kellee Crisafulli [mailto:kellee@hyperlynx.com]
> > Sent: Monday, 07 June, 1999 2:19 PM
> > To: Beal, Weston; ibis@eda.org
> > Subject: RE: [SI-LIST] : IBIS Subcommittee Formed to
> > Review Spice to IBIS
> >
> > Hi
> >
> > I have a comment on Weston's comment on the number of data
> > points.
> > I disagree on one point. Instead of increasing the number
> > of points generated
> > in the IBIS file the spice to IBIS tool should improve the
> > quality of the
> > points
> > choosen.
> >
> > I can hand build files with 50 points that out perform files
> > with 400 points.
> > The big gain is that the FILE SIZE is reduced with higher
> > accuracy.
> > Large IBIS files will take up many megabytes on 1000's of
> > hard drives.
> > The V/I and V/T tables are the largest part of IBIS files.
> > Increasing them 4 x will generally increase the file size 3
> > x or more.
> >
> > >The third thing that I changed was the number of points in
> > the time
> > >waveforms from 50 to 101. I have to remove one point to
> > comply with the
> > >golden parser, but I get better detail. On the issue of
> > number of points in
> > >a curve or waveform, I think the user should be able to
> > define any degree of
> > >granularity and the IBIS creator tool should have an
> > algorithm to remove
> > >points in linear regions. If the resulting curve still has
> > too many points,
> > >then increase the linearity tolerance and try it again.
> >
> > Best wishes...
> > Kellee