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Spectre TRAN noise analysis ends with memory fault after warning: (SPECTRE-16780): LTE tolerance was temporarily relaxed to step over a discontinuity in the signal:

vivkr

I am trying to simulate a very simple circuit (no AHDL, VerilogA) with the TRAN noise analysis using Spectre TRAN noise analysis (MMSIM versions 12.10.347 and 12.10.402 tried).

During the course of the simulation, I get a warning message:

 WARNING (SPECTRE-16780): LTE tolerance was temporarily relaxed to step over a discontinuity in the signal

After this point, nothing further happens and I can see that the spectre job is dead. Investigating further with a trace program tells me that a memory fault has occurred, e.g.

  /tools/cds/MMSIM/12.10.402/tools/bin/spectre[533]: wait: 18468: Memory fault

Interestingly, this cannot be due to insufficient memory as:

1) That one usually elicits an explicit "memory exhausted" error from Spectre, and

2) The trace program tells me that Spectre was using upto 1 GB RAM but I had allocated 10 GB for it (and later even 40 GB in order to figure out if there might be peak memory usage at much higher levels that my trace program missed as I strobe only every few seconds).

Any useful suggestions to solve the problem would be most welcome. I do not wish to use PSS/PNOISE analysis as that usually takes longer and I can only look at one output at a time there.

Thanks,

Vivek

Parents
  • vivkr

     Andrew,

    1) Thanks! I am running the 64-bit version of Spectre but I suspect just like you that this is not a typical out-of-memory error. 

    2) There are no inductors in the circuit.

    3) I have got cmin turned on but not set = 1fF but 1aF. I can try to increase it to 10aF but 1f would be too much for me.

    4) I don't see the option for measuring noise at multiple places with the version of ADE-L I am using, but anyway, I did try using multiple pnoise statements. It works that way but seems just an enormous waste of CPU time given that it is much slower than TRAN noise. I suppose I'll just have to live with that.

    5) I will try to send out a test case via our rep. I doubt if I am allowed to directly send over data outside the company.

    Regards,

    Vivek

     

Reply
  • vivkr

     Andrew,

    1) Thanks! I am running the 64-bit version of Spectre but I suspect just like you that this is not a typical out-of-memory error. 

    2) There are no inductors in the circuit.

    3) I have got cmin turned on but not set = 1fF but 1aF. I can try to increase it to 10aF but 1f would be too much for me.

    4) I don't see the option for measuring noise at multiple places with the version of ADE-L I am using, but anyway, I did try using multiple pnoise statements. It works that way but seems just an enormous waste of CPU time given that it is much slower than TRAN noise. I suppose I'll just have to live with that.

    5) I will try to send out a test case via our rep. I doubt if I am allowed to directly send over data outside the company.

    Regards,

    Vivek

     

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