[SI-LIST] Re: Algorithm to interpolate ramp data in IBIS
- From: "BHAGWATH,NITIN (HP-Roseville,ex1)" <nitin.bhagwath@xxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 21 Nov 2003 13:47:21 -0500
Thanks for the response, Andy.
We are going the IBIS route because the spice model is quite large and
simulation times take upto half a day. For first run estimates and
hypothetical situtations, IBIS should be sufficient.
That said, I'd still like to get the maximum I can out of the IBIS model.
There are regions in the rampup/down curve which are non-linear, and I'd
like to capture the maximum information from the given data. Afterall, it's
only a little more work to make a script to optimise data gathering. I just
didn't want to end up distorting the data by gathering the wrong points.
Once again, Thanks
-Nitin
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Ingraham, Andrew
Sent: Friday, November 21, 2003 6:07 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Algorithm to interpolate ramp data in IBIS
Nitin,
I would not assume anything whatsoever about how points are either
interpolated or extrapolated. IBIS does not specify.
Some simulators might extrapolate using the slope of the last two points at
the beginning and end ... but I would expect that this is a Really Bad Idea.
Linearly extending the ends using any non-zero slope is guaranteed to give
unreasonable values if you extend far enough. If the waveforms are from
measured data, then the slope won't be zero.
The IBIS checker (Golden Parser) assumes a zero slope ... that the ONE point
on each end represents the steady-state value.
For interpolation, I would guess that you might find either linear
interpolation or a spline curve interpolation being used.
Does removing points really make that much of a difference? As long as you
have enough points in areas with large curvature (change in slope), can you
really see a difference in your simulation results if you remove points
where the slope isn't changing? After all, it's only IBIS. Were you
expecting extreme accuracy?
There is nothing wrong about non-uniform time points. IBIS does not expect
them to be uniform.
(If you have a SPICE model, why not keep it in SPICE? Why convert it to
IBIS? Who are your model users?)
Regards,
Andy
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
