Re: [SI-LIST] : Custom measurements in Specctraquest(Sigxp)

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From: Donald Telian (donaldt@cadence.com)
Date: Thu Sep 07 2000 - 10:18:09 PDT


Aloke,

Excellent questions. Please see answers below...

Donald T.

At 09:15 PM 9/7/00 +0530, Aloke Bhattacharya wrote:
>Hello all,
> For performing custom measurements for a source synchronous bus in
>sigxp, I need to extract
>the topologies of both the data line and the strobe line together in
>sigxp. I don't see any option of extracting multiple xnets together in
>sigxp. Currently I don't see any way of extracting the data and strobe
>together other than editing the netlist in Specctraquest and adding some
>very high value(say 1Meg ohm) resistor between the strobe and data. Is
>there any other way of extracting the data and strobe together in sigxp?

Today, SPECCTRAQuest does not extract multiple (or coupled) nets into
SigXp at once. Your 1MEG resistor idea is clever, and may get you what you
want.

>As I am having more than 7 or 8 groups of source synchronous buses in
>the design, editing the netlist for each of them is time consuming. I
>know that for simulating both the xnets together I need to add a high
>value resistor between them because sigxp will not simulate two
>disconnected circuits as it uses a SPICE type simulator. But what I
>would like to do is to add the high value resistor in Sigxp(after
>topology extraction), and not in Specctraquest because adding the
>resistor in sigxp is lot more easier.

I often simulate multiple nets in SigXp by combining them through a
coupled trace model. But the large resistor idea does work too. I'll
send you some source-sync examples files (associated strobes, custom
measurements, coupled nets...) in a separate email that should help.

>Hence, my problem will be solved if any one of the following is
>possible:
>(i)Extract two xnets simultaneously in Sigxp
>(ii)Extract two separate xnets in two separate sigxp windows and copy
>one into the other
>The second option is something normally available in a schematic editor,
>but I am not sure whether it is available in the topology editor Sigxp.
>

SigXp does not yet support cut and paste. However, topology files are
just text-based so it may be possible to extract them both separately
and then hack the text together. I haven't tried this yet, and it wouldn't
be for the faint-hearted, but it just might work for the short term. If it
turns out you need to draw them, the drawing tools and browsers should
make that simple enough. You could also record a script macro of the
drawing steps that might help you draw the next one even quicker.

>Finally, I would like to know whether it is possible to perform custom
>measurements directly in Specctraquest. In one of the source synchronous
>buses the strobe is a differential pair and I cannot extract that in
>sigxp because extraction of differential pair is not supported in sigxp.
>Hence, I can not perform a cutom measurement for this bus unless it is
>possible to do custom measurements directly in Specctraquest!!
>

Custom Measurements is a very powerful feature. We knew it was needed,
so in adding it into the tool we elected to add it to the pre-route solution
first because users primarily wanted to use it for solution space sweep
analysis. The same measurement architecture will be available at the board
level in SPECCTRAQuest in an upcoming release. In the mean time, I'll forward
you a script you can use to post process SQ waveform files to get the
measurement
you need. Note that today you CAN draw your differential net in SigXp and
take
advantage of the custom measurements functionality there.

>Thanks and regards,
>Aloke
>
>
>--
>**********************************************************************
>* Aloke Bhattacharya, *
>* Senior Engineer-VLSI/System Design,
>* *
>* Wipro Infotech, *
>* Global R&D, *
>* 88, M.G. Road, 5th Floor, *
>* S.B. Towers, *
>* Bangalore- 560 001 , *
>* INDIA *
>* Tel : 91-80-5588422(Ext. 520) *
>* email: aloke.bhattacharya@wipro.com
>* *
>**********************************************************************
>
>
>
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>
Donald Telian
Cadence Design Systems
phone: 408-944-7791
donaldt@cadence.com

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