Stats

  • Locked Locked
  • Replies 5
  • Subscribers 124
  • Views 6467
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Convergence error working with compMacro model from the functional library

FormerMember
FormerMember

I was trying to simulate a circuit using "compMacro" instance in a simple test-bench using spectre (sub-version  IC6.1.8-64b.500.3 ").

However, in any simple configuration, also as mentioned in the user guide, I receive "Convergence error" 

I have included the functional library properly (it works for other instances from the library), but a simple DC or Transient analysis will not converge. The model has the default values but yet It is not working.

 

ERROR (SPECTRE-16385): There were 7 attempts to find the DC solution. In some of those attempts, a signal exceeded the blowup limit of its quantity. The last signal that failed is V(X0.2) = -3.01172 GV, for which the quantity is `V' and the blowup limit is (1 GV). It is possible that the circuit has no DC solution. If you really want signals this large, set the `blowup' parameter of this quantity to a larger value.
ERROR (SPECTRE-16080): No DC solution found (no convergence). 

Parents
  • Andrew Beckett

    Perhaps you can show the configuration you're using, or better still provide the input.scs so that I can take a look?

    Otherwise I'd have to guess what you're doing.

    Also, which version of spectre are you using (probably not critical for the issue - you've mentioned the IC version, not the spectre version - that will appear at the top of the spectre log file)?

    Thanks,

    Andrew.

  • FormerMember
    FormerMember in reply to Andrew Beckett

    Hi Andrew,

    I wonder how can I attached my scs file as a file? Via Insert icon I can see the code appears completely. Is it fine?

    Imabn

Reply
  • FormerMember
    FormerMember in reply to Andrew Beckett

    Hi Andrew,

    I wonder how can I attached my scs file as a file? Via Insert icon I can see the code appears completely. Is it fine?

    Imabn

Children
  • Andrew Beckett
    in reply to FormerMember

    If you insert image/media/file then it does attach it as a link and then for convenience shows the text in a scrollable window in the forum. I have downloaded the file you provided (before you deleted the post) and so am playing with that right now.

    Andrew 

  • Andrew Beckett
    in reply to Andrew Beckett

    Looking in the model, it seems that the resistor RX ends up being very large inside the macro model, and if you start off with a voltage of 3.3V at the negative input at time 0, you'll hit this blow-up voltage as it generates current into a very large resistor. If you start with the 0V at the first time point on your PWL source, then it converges and behaves - it does not have this blow up issue.

    The functional library is very old and has not been actively maintained. I would discourage you from using it - it would be better to use a comparator from (say) ahdlLib which is a VerilogA component library instead. Macro models are the way things used to be done 25 years ago before analog behavioural models became more commonplace.

    Regards,

    Andrew.

  • FormerMember
    FormerMember in reply to Andrew Beckett

    Hi Andrew,

    Thank you.

    I am now working with the comparator from ahdLib library, (however it has less parameters modeling the comparator), and it works properly.

    Regards,

    Iman

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.