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Convergence Problems with spectre

eppo

Hello,

I have a Verilog-A model which works very well in dc analysis, by cons when I try to work with transient analysis I have the  following error message:

ERROR (SPECTRE - 11005) : Matrix is singular (detected at 'net09').

ERROR (SPECTRE - 16080) : No DC solution found (no convergence). 

How can I solve this problem. 

 

Thanks, 

 

  • Hi eppo

    First step to solving convergenece issue is to try with the latest version of spectre. If you think that there is no problem with the verilogA model, install and try the latest MMSIM package. : )  If it is possible, it would also be good for you to provide more details about the model.

    Best regards
    Quek

  • Thank you Quek for your answer. Indeed, in DC simulation I have 3 same warning but it simulates : Line 160 : Warning: dependencies passed throught array arguments ignored. can cause potential convergence problems. I think that is the problem of convergence (warning) that creates a problem in transient simulation. Line 160 ==> I(Vdrain,Vsource)
  • Thank you Quek for your answer. Indeed, in DC simulation I have 3 same warning but it simulates : Line 160 : Warning: dependencies passed throught array arguments ignored. can cause potential convergence problems. I think that is the problem of convergence (warning) that creates a problem in transient simulation. Line 160 ==> I(Vdrain,Vsource)
  • Thank you Quek for your answer. Indeed, in DC simulation I have 3 same warning but it simulates : Line 160 : Warning: dependencies passed throught array arguments ignored. can cause potential convergence problems. I think that is the problem of convergence (warning) that creates a problem in transient simulation. Line 160 ==> I(Vdrain,Vsource)

  • Eppo,

    None of your last three (repeated) appends to this post make any sense!

    Regards,

    Andew.

  • Hi, I enclose a verilog-A code with the last post code, but it does not appear. // Function that calculates current analog function real Icourant1; input P,Gamaid,Gamadi; real P[-20:20],Gamaid[-20:20],Gamadi[-20:20]; real Ptotal; integer n; begin Ptotal=0; for(n=-20;n
  • I do not know why when I post the message does not appear completely

  • Perhaps you should just file a service request with customer support. Even with just the Verilog A model alone, it is unlikely to be enough to debug the problem - usually would need to see how it is being used in the circuit. Often convergence issues are due to interactions between the models and the rest of the circuit.

    Regards,

    Andrew.

  •  Hi Andrew,

    In fact it is a Verilog-A transistor model . The circuit I'm trying to simulate is two transistors in series. Indeed I haven't problem with the DC simulation (Id-Vds) of a single transistor, but I have a warning on one line of code that say''dependencies on thought Passed array arguments ignored. Cdn cause potential convergence problems ".

    I (Vdrain, Vsource) <+ I (P, Gama1, Gama2) // knowing that P,Gama1, Gama2 are tables reported before.

     

    Regards, 

  • Eppo,

    As I've said before, this is insufficient information to be able to debug anything (try imagining yourself on the receiving end - even with expertise, do you think what you've described so far would be enough for anyone to be able to pinpoint the problem?). A message such as you describe seems rather unlikely - whilst our messages aren't always grammatically correct, this just doesn't look like the kind of thing the simulator produces - so maybe you've paraphrased it? Or misread it?

    The best thing to do is to provide the model, the netlist you're using to simulate it, and the output log file. As I said earlier, please do this via customer support.

    Regards,

    Andrew.

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