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  3. How to preserve parasitic nodes in extracted spice netlist...

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How to preserve parasitic nodes in extracted spice netlist with APS++/parasitic reduction

twen
twen over 9 years ago

I am using APS++ and parasitic reduction to speed up the simulation so the simulation can run to completion within hours.  Some cells in the config are bound to the extracted spice netlists. I manually save the node voltages inside the extracted spice netlists which are located on selected points on certain metal layers when I run the simulation by including the save statements. When I enabled the parasitic reduction, most saved nodes are blown away so I can not probe the internal parasitic nodes. There is an "instance preservation" option and I have used it with limited success. I say "limited success" because I have thousands or more nodes to save and I have to go into the netlist and find the instance names corresponding to the node names. This is not practical unless I build my own parser which reads in the saved nodes and outputs the preserved instances. Here is the version information "@(#)$CDS: virtuoso version 6.1.6-64b 12/07/2015 20:18 (sjfbm186) $."

My question now: is there an option or trick to force the parasitic reduction algorithm to mark and preserve the nodes and instances if these nodes or instances are in the save statement or match the save wild card patterns? Unmarked parasitic nodes and instances can still be trimmed to speed up the simulation.

Thank you in advance,

TJ

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  • Andrew Beckett
    Andrew Beckett over 9 years ago

    TJ,

    It's more important to know which spectre version you're using (the IC version is irrelevant in this case). You'll see that at the top of the spectre.out log file.

    From some quick searching, this should work from an MMSIM14.1 ISR (not sure which version), but I see there were some fixes added in MMSIM15.1 (that was actually related to the save statements turning off reduction altogether in some cases which it shouldn't have done). 

    The advice is to ensure that you put sigtype=node on the save statement with the wildcard, but I'd first make sure you're using a recent enough MMSIM version.

    Kind Regards,

    Andrew.

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  • Andrew Beckett
    Andrew Beckett over 9 years ago

    TJ,

    It's more important to know which spectre version you're using (the IC version is irrelevant in this case). You'll see that at the top of the spectre.out log file.

    From some quick searching, this should work from an MMSIM14.1 ISR (not sure which version), but I see there were some fixes added in MMSIM15.1 (that was actually related to the save statements turning off reduction altogether in some cases which it shouldn't have done). 

    The advice is to ensure that you put sigtype=node on the save statement with the wildcard, but I'd first make sure you're using a recent enough MMSIM version.

    Kind Regards,

    Andrew.

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