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regarding simultion convergence issues

fazul

Hi everybody!

i have a question regarding  simulation convergence.. I am running a Transient Noise Analysis

with errpreset = conservative. Initially it was having difficultly in converging so i tried the usual techniques

like relaxing abstol, reltol, increasing maxiter, method=gear2only as it was mentioned in the manuals.

Now the simulation seems to run to completion without errors but with a large number of warnings and notices from spectre.

----------------------------------------------------------------------------------------------

WARNING : The bulk-source junction current exceeds `imelt'. The results computed by Virtuoso(R) Spectre are now incorrect because the junction current model has been linearized

WARNING :Vgd has exceeded the oxide breakdown voltage of `vbox'

WARNING : Minimum time step used.  Solution might be in error.

.....

spectre completes with 0 errors, 4672 warnings, and 2409 notices

----------------------------------------------------------------------------------------------

my question is how reliable is the simulation result in this case. At a glance the result seems to be correct but can i really ignore all these warnings and trust the result?

what is the general approach that a CAD engineer takes when he is faced with these kind of warning?

Forgive me if my question is not clear, i am quite new to simulation and havent completely understood  how  spectre/spice simulators work . So any pointers will be very helpful...

Thanks a lot, have a nice day.

Fazul 

 

Parents

  • I will defer your questions to others and instead ask two of my own.  1) Are you running 64-bit Spectre?  I've seen issues with convergence and 32-bit.  2) It sounds like you have an IBM PDK.  Are you running the supported version of Spectre? 

Reply

  • I will defer your questions to others and instead ask two of my own.  1) Are you running 64-bit Spectre?  I've seen issues with convergence and 32-bit.  2) It sounds like you have an IBM PDK.  Are you running the supported version of Spectre? 

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