Re: [SI-LIST] : Noise Margin Vs XTK simulation

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From: Mike LaBonte (mike@labonte.com)
Date: Thu May 31 2001 - 08:32:19 PDT


Senthil,

In my experience the sum of peaks is too often extremely
pessimistic, especially for dense designs. The RSS estimate
is usually pretty close to the actual crosstalk for a typical
data pattern, as determined by AllNeighbors simulation in
SPECCTRAQuest. Usually the RSS value is greater than or equal
to the single aggressor peak, but I would look for a way to
take the greater of RSS and single aggressor peak just in case.
I think some people take the RSS and increase it a bit with
some fudge factor.

Crosstalk is not the only noise source, so hopefully you
are also weighing other noise sources against your noise
margins. The simplest method is to sum all noise sources
before comparing against noise margin.

Mike LaBonte

Senthil.Selvam@smartm.com wrote:
>
> Hi Si gurus,
> I am working with SI group on Pentium AGTL+ simulation. I worked out the Noise
> margin for
> Low and High level separately. For a victim net, XTK(Innoveda Tool) gives a
> text report of cross talk from each aggressor net.
> It gives a). Peak values(in mV) due to each aggressor, b). Sum of peaks and c).
> Root Square Sum(rss) of peaks.
>
> Now which of the above figure should be less than Noise margin value I computed
> ?.
> Also how XTK result values to be compared with High or Low level Noise magin ?.
> If my question is wrong how to use the results of XTK to ensure that the Noise
> margin is met ?
>
> Please someone shed more light on this issue.
> Thanks
> Senthil, Design Manager, FORCE Computers India Pvt Ltd, Bangalore-20.
>
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