[SI-LIST] Re: Ringback measuremenr with HSPICE
- From: "hreidmarkailen" <hreidmarkailen@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Sat, 20 Aug 2005 16:15:11 -0400
The Short Answer: very unreliably with just .measure statments.
You could just display the eye in avanwaves but maybe you need numbers and
want to automate it.
If so... watch out what you ask for...
CosmoScope and/or Verilog-A from Synopsys may work better, and either are
perhaps adaptable to the method below in last 2 paragraphs. I don't have
the time to expand further. My info here may not be the last word, just my
2 cents worth. Caveat emptor.
I remember a company where they addressed this with C programs to
postprocess *.lis output, actually doing dv/dt to reliably find the
amplitudes per bit period. But that complexity is not necessary and it
also didn't, as implemented, determine the noise margin in the critical
timing windows, for clocked data in that case. We only "care" about the
noise margin in the timing windows, whether UI based or setup/hold based.
Separately, one might be concerned about max. ringback in terms of stress on
the silicon, w/o regard to rcvr timing, but I assume you want the ringback
info only in terms of timing violations.
My solution, for only ringback's timing impact, is to implement the
following postprocessing in a spreadsheet (or Perl if you're a fanatic).
StarOffice [?] has a good spreadsheet for Unix I believe. Determine the
timing budget and flight times and parametrize eye-mask boundaries in the
tool of choice, then postprocess *.lis, finding the ringback that violates
the mask. This involves finding simple voltage differences between signal
and mask. Time sample-points of your mask and *.lis won't match, so
interpolation is required.
It's not simple and a bit of tedium, parametrization and trial may be
required, but it's extensible and reusable for all changes to the layout and
interconnect, and adaptable for future problems of other kinds. However,
each problem class will require its own version. The method is simple
subtractions but the total effort is inversely proportional to the
simplicity of method I guess.
...... Postscript .......
Alas, the simple things are made difficult by the CAD tool vendors. I
believe it's a form of revenge or something, by some inscrutable logic.
They don't have to actually use their tools to make money, just like our
Congress isn't subject to what we are.... The ancients, seeking refuge from
the volcanoes, must've felt something similar ... and a bit more severe.
They placed their faith in the high priests who, as it turned out, were
simply.... high. And nothing else. But I digress. Gotta run. Good luck
in your quest.
-Agathon
----- Original Message -----
From: "Khan, Mohammad I" <mohammad.i.khan@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Thursday, August 18, 2005 9:59 PM
Subject: [SI-LIST] Ringback measuremenr with HSPICE
> Hi Guys:
> How do we measure the maximum Ringback (from VCC to ViH and from VSS to
> ViL) using HSPICE.
>
> Thanks
>
> Ibrahim
>
>
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----- Original Message -----
From: "Khan, Mohammad I" <mohammad.i.khan@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Thursday, August 18, 2005 9:59 PM
Subject: [SI-LIST] Ringback measuremenr with HSPICE
> Hi Guys:
> How do we measure the maximum Ringback (from VCC to ViH and from VSS to
> ViL) using HSPICE.
>
> Thanks
>
> Ibrahim
>
>
> ------------------------------------------------------------------
> 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
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>
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> or at our remote archives:
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