The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> Circuit Simulators >> AC analysis in spectre
https://designers-guide.org/forum/YaBB.pl?num=1494933873

Message started by Gp on May 16^th, 2017, 4:24am

Title: AC analysis in spectre
Post by Gp on May 16^th, 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

Title: Re: AC analysis in spectre
Post by Ken Kundert on May 16^th, 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

Title: Re: AC analysis in spectre
Post by Geoffrey_Coram on May 16^th, 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.

Title: Re: AC analysis in spectre
Post by AMS_ei on May 19^th, 2017, 11:42pm

spectre doesn't normally use ".ac" since that is the archaic SPICE syntax rather than spectre's own more regular syntax

Title: Re: AC analysis in spectre
Post by Andrew Beckett on May 28^th, 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.