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AC analysis in spectre (Read 489 times)
Gp
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AC analysis in spectre
May 16th, 2017, 4:24am
 
Hi All,

I want to run AC analysis of Low pass filter with cadence spectre. With transient analysis, it's working fine But during AC analysis following error generated:

******************************************************
AC Analysis `frequencySweep': freq = (1 Hz -> 100 MHz)
******************************************************
DC simulation time: CPU = 11.999 ms, elapsed = 42.51 ms.

Opening the PSF file /home_ei/pdubey_ei/Desktop/gp_test/VAMS_examples/LPF/amscf.raw/frequencySweep.ac
...
ncsim: *F,INTERR: INTERNAL EXCEPTION
Observed simulation time : 0 FS + 2
-----------------------------------------------------------------



My spectre.scs file is following:

simulator lang=spice

.AC DEC 5 1 100e6


simulator lang=spectre

myopts options duplicate_subckt=warning
myinfo info what=oppoint where=rawfile
spectre options diagnose=detailed debugstepdrop=yes simstat=detailed debug=yes duplicateinstance=warning duplicatemodel=warning


So, Kindly give the solution.

Thank you


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Ken Kundert
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Re: AC analysis in spectre
Reply #1 - May 16th, 2017, 9:32am
 
You should contact Cadence when you have an internal error.

An internal error is a reaction to some unusual or unexpected condition. To work around it, you should try to identify anything you are doing that is unusual and then get rid of that thing to see if the error goes away.

-Ken
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Geoffrey_Coram
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Re: AC analysis in spectre
Reply #2 - May 16th, 2017, 1:32pm
 
I'd get rid of the two options statements and the info, to start (I'm particularly curious about "spectre" as a possible keyword and the name of your second options statement).

And I'd re-write your .ac line in Spectre syntax.

Not that Spectre shouldn't be able to handle it, but along the lines of Ken's suggestion, eliminate anything weird.
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AMS_ei
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Re: AC analysis in spectre
Reply #3 - May 19th, 2017, 11:42pm
 
spectre doesn't normally use ".ac" since that is the archaic SPICE syntax rather than spectre's own more regular syntax
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Andrew Beckett
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Re: AC analysis in spectre
Reply #4 - May 28th, 2017, 9:53am
 
It's also a good idea to mention which version of the simulator you're using, in case this is a known problem. In this specific case there's not enough information to be going on (it's pretty unlikely that all ac simulations fail because that would be picked up prior to the software being released).

However, if you're running an old version of spectre, I'd always suggest trying a recent version just in case the specific issue you're hitting has been solved subsequently.

I was able to run an AC simulation using a simple circuit together with  your other statements in SPECTRE161 with no problem at all.

Regards,

Andrew.
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