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ic_engr

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Output Paramaters in pss
Jan 10^th, 2006, 9:31am

I am running pss-pnoise simulation for my circuit. Due to the long simulation time I have, and lmitation in memory I would like to print the outputs of interest only after some time e.g 1.25msec. How can I do the setting in PSS to get outputs after a time delay. I know in transient analysis we can use the "outputstart" to specify the time afterwhich we can printout the outputs. Is there similar option for PSS. I tried "skipstart" but that did not work.

I appreciate feedbacks.

Tx

ic_engr

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Geoffrey_Coram Senior Fellow Offline Posts: 1999 Massachusetts, USA	Re: Output Paramaters in pss Reply #1 - Jan 10^th, 2006, 10:52am What about the tstart and tstab parameters? Are you interested in skipping the initial transient, or skipping some portion of the PSS period?
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ic_engr Senior Member Offline Posts: 135	Re: Output Paramaters in pss Reply #2 - Jan 10^th, 2006, 12:52pm I am interested to skip the initial transient and not the PSS period. ic_engr
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Geoffrey_Coram

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Re: Output Paramaters in pss
Reply #3 - Jan 12^th, 2006, 6:01am

Maybe I'd better let Andrew answer this one. I looked up skipstart in "spectre -help pss" and saw:

21 skipstart=starttime s
The time to start skipping output data.
22 skipstop=stoptime s
The time to stop skipping output data.

but starttime and stoptime aren't parameters. But I would expect some combination of these parameters with tstart and tstab would get you what you wanted.

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Andrew Beckett

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Re: Output Paramaters in pss
Reply #4 - Jan 12^th, 2006, 10:44am

Well, I don't think skipping points during the initial transient will save you anything significant in terms of memory - might in terms of disk space though...

You can of course just not save the initial transient at all (this is controlled by the saveinit parameter, which defaults to no). If you do want to save it, but not output (much) data until a specified time, you could always do:

skipcount=10000 (or some large number)
skipstop=1.25m

skipstart defaults to tstart (usually 0), and skipstop will default to the end of the tstab (i.e. onset of periodicity+tstab+1 period).

What the above will do is only output every 10000th time point, until you reach 1.25ms, and then it will output all of them.

Why have you got such a long initial transient? Do you really need it to be so long?

Regards,

Andrew.

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ic_engr

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Re: Output Paramaters in pss
Reply #5 - Jan 12^th, 2006, 3:38pm

Andrew,

I have an oscillator running at 16MHz. It takes about 1.25msec for the dutycycle as well as the shapes of the sinusoidal outputs to settle. I am using the tstab=1.28msec. However, I do not want to PLOT any data output until tstab=1.28msec. So what will be the setting I should use in pss OPTIONS.

After tstab I ofcourse want to see the periodic result and then pnoise.

I appreciate your response.

Tx

ic_engr.

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Ken Kundert Global Moderator Offline Posts: 2386 Silicon Valley	Re: Output Paramaters in pss Reply #6 - Jan 13^th, 2006, 8:45am saveinit=no tells Spectre to not save waveforms for the tstab interval. -Ken
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ic_engr Senior Member Offline Posts: 135	Re: Output Paramaters in pss Reply #7 - Jan 16^th, 2006, 8:16am Thanks Ken, It worked. ic_engr
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