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Murat H. Eskiyerli

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Transient simulation results are not plotted after 18.45ms
Oct 07^th, 2009, 6:21am

I am trying to simulate a simple integrate and dump circuit. Because the integration time is quite long (around 40ms), I need to simulate the circuit for a long time, maybe half a second. When I simulate using Spectre 7.0.1.076 version, the simulator runs fine, but it cannot display transient results for more than first 18.45ms. I checked it with a couple of circuits, even with a simple CMOS inverter and it still has the same problem. What could be going wrong?

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Riad KACED

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Posts: 93
Swindon, UK

Re: Transient simulation results are not plotted after 18.45ms
Reply #1 - Oct 7^th, 2009, 2:12pm

Hi Murat,

My first thought was that your results are saved in SST2 format (deafult in your MMSIM version) and when your file gets over 2G size then the display would stop is using wavescan. Well, assuming 18.5ms would dump a big enough file to reach the 2G limit, I was going to propose switching back to psf and use the chunk option.

But since this behaviour occurs for even an inverter, then I would advise checking your data integrity. i have seen similar problems with people loosing data when running over a load sharing system.

Well, I still believe there is something wrong and you need to check your Unix files.

Going back to the first big file, give it a look at the following:
http://www.designers-guide.org/Forum/YaBB.pl?num=1238006736/1#1

Would you mind posting your Cadence versiuon as well ? i.e. icfb -W
and tell us which viewer you are using: awd, wavescan ... etc

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Riad KACED
PDK, EDA Support Engineer.

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Murat H. Eskiyerli

Ex Member

Re: Transient simulation results are not plotted after 18.45ms
Reply #2 - Oct 10^th, 2009, 1:28pm

Hi Riad,

This is the output of icfb -W command:
sub-version 5.10.41.500.5.122

I don't think it is a file size issue as I am simulating a circuit with ideal elements and thus the file file size very small: tran.tran file in the psf directory is only 32.1kB. I tried the workaround described in the post you gave a link to and it worked. I am not sure I understand the difference between file formats, but it seems quite strange.

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pirate

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Posts: 7

Re: Transient simulation results are not plotted after 18.45ms
Reply #3 - Oct 14^th, 2009, 10:05am

Hi Murat,
we had the same issue with 5141 USR5, try 5141 USR6, latest sub is 139 I believe.

bug # might be:
"00617461 � icms wavescan calculator does not plot expression (v("net10" ?results "./ampsim.raw" ?result "tran-tran")"

"00597358 � Problem with wavescan while browsing the sst2 database"

You can also try plotting the result in stand-alone w/o the icfb+ADE overhead.
Type
>wavescan -expr MDL
in your simulation directory, then load your transient results.

P

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Riad KACED

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Posts: 93
Swindon, UK

Re: Transient simulation results are not plotted after 18.45ms
Reply #4 - Oct 15^th, 2009, 2:58pm

Hi Murat,

Well, given the size of you files, both PSF and SST2 would correctly read the files unless a bug as mentioned by Pirate.

You definitely need to upgrade your Cadence version though, ask your EDA guy to update your settings with the latest IC5141 versions.

As for the PSF versus SST2 difference then I would say in summary that SST2 is better in terms of performance and is reading the data faster than PSF as it loads only what needs to display. Also SST2 is the format used in AMS Designer (simvision) and Ultrasim. STT2 has no size limitation limit as PSF. STT2 files can virtually go up to very high, what limits you is your hardware !

The take away message here is to get you IC5141 upgraded !

Cheers,
Riad.

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Riad KACED
PDK, EDA Support Engineer.

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