[SI-LIST] Re: Problem in converting IBIS2XTK
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: Si-list@xxxxxxxxxxxxx
- Date: Fri, 19 Oct 2001 10:45:06 -0700
Good point, Al. I just wonder whether that is really the
reason XTK (or other tools) does it.
Arpad
===========================================================
-----Original Message-----
From: Al Davis [mailto:aldavis@xxxxxxxx]
Sent: Thursday, October 18, 2001 9:21 PM
To: arpad.muranyi@xxxxxxxxx; Si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: Problem in converting IBIS2XTK
On Thursday 18 October 2001 10:19 am, Muranyi, Arpad wrote:
> 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.
But the point removal is not to reduce the point count. One reason
for it is to clean up the derivative. Too often, the tables provided
are contaminated by noise. Removing some points reduces the noise.
This noise sometimes causes wild excursions of the derivative, when
the measurement precision does not justify it.
This noise in the derivative also causes problems in waveform
generation.
Why is it that no ibis-view tools or simulators show the derivative?
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