[SI-LIST] Re: Problem in converting IBIS2XTK
- From: "Grigoras, Adrian C" <adrian.c.grigoras@xxxxxxxxx>
- To: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>, Si-list@xxxxxxxxxxxxx
- Date: Thu, 18 Oct 2001 11:36:45 -0700
Which begs the question .. how good is "good" in terms of visually comparing
these waveforms ? ...
I know Greg Edklund of IBM had an utility out there performing a numerical
correlation between 2 waveforms, but I had hard time getting results...
Adrian Grigoras
Intel Corp.
-----Original Message-----
From: Muranyi, Arpad [mailto:arpad.muranyi@xxxxxxxxx]
Sent: Thursday, October 18, 2001 9:20 AM
To: Si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Problem in converting IBIS2XTK
Mike, Ramesh,
I found that we have to be very careful about removing points from
the IV curves. Reason: Reflection coefficients are determined by
the slope of the IV curve (AC impedance), not the actual R=V/I at
a given point. Depending on how the simulator handles the
discontinuity that arises at each of these points when using
simple linear interpolation, one could get interesting results.
Assuming that this is done properly with good interpolation
techniques, the accuracy of the slope at a given point may still
be more sensitive to the spacing between points than R calculated
from V/I. So we can't just say that we got a good correlation
between the reduced points curve and the original curve by looking
at how close the two curves overlap. We would need to make a
judgment using the overlay of their derivatives.
Arpad Muranyi
Intel Corporation
====================================================================
-----Original Message-----
From: Mike LaBonte [mailto:mike@xxxxxxxxxxx]
Sent: Thursday, October 18, 2001 8:54 AM
To: Ramesh.Reddy@xxxxxxxxxx
Cc: Si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Problem in converting IBIS2XTK
Ramesh,
When two IBIS simulators show significant differences for the same
IBIS data, I suspect a mismatch between the V/I curves and the
Rising and Falling waveforms first. If ibischk3 gives you warnings
about this, that probably explains the difference.
Mike Mayer is right about ibis2xtk removing points. It does a
good job of this, in that the filtered curve overlays the original
almost perfectly, to the human eye. The simulated waveforms will
also look good visually. The effects of this filtering only show
up in the high end of the frequency spectrum, where the smaller
V swings are now seeing smaller dI/dV changes with the filtered
data. Unless you look at the FFT, or are doing crosstalk analysis,
you will not see the difference. But you don't really know if the
original V/I data had those small perturbations characterized
correctly anyway.
Mike LaBonte
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