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Can run simulation with MMSIM72 but cannot run with MMSIM62

abyan

 Hi,

in my lab we use two linux server (5.2) for cedence (5.10.41....).

For running ADE simulator, one machine use MMSIM72, and the other one uses MMSIM62.

Edit: For a certain PDK,

I can run simulation successfully with MMSIM72, but running it with MMSIM62 always gives convergence errors, like this:

~~~~~~~~~~~~~

Error found by spectre during IC analysis, during transient analysis `tran'.
    ERROR (SPECTRE-16080): No DC solution found (no convergence). 

The values for those nodes that did not converge on the last Newton iteration are given below.  The manner in which the convergence criteria were not satisfied is also given.
            Failed test: | Value | > RelTol*Ref + AbsTol

    V(CLK) = 0 V
        residue too large: | -12 uA | > 60.0001 nA + 1 pA

 

******************
DC Analysis `dcOp'
******************

Error found by spectre during DC analysis `dcOp'.
    ERROR (SPECTRE-16041): Analysis was skipped due to inability to compute operating point.
Warning from spectre during DC analysis `dcOp'.
    WARNING (SPECTRE-16518): Arithmetic exception in analysis `dcOp' .

~~~~~~~~~~~~~ 

My question: is using MMSIM72 the only thing I can do to solve this problem?

 

best regards,

sigit

  •  Hi Sigit,

    without knowign the circuit and the models I can't say why 6.2 is failing and 7.2 not. Maybe a bug, maybe some enhancements in 7.2.
    The question is, why do you want to run 6.2 if you have 7.2? 6.2 is nor supported anymore and is not tested for Red Hat 5 anyway ( only RHEL3 and RHEL4).  Any specific reason you need to run 6.2?

    Kind regards,

    Marc

  • hi marc,

    the machine with mmsim62  is actually a backup; it is rather slow but has bigger HDD space for my simulation since not many people use it.

    I am also wondering why only one particular PDK cannot be simulated.There are about eight PDK installed; all can be simulated with MMSIM62, except this one.

    sigit

  • As Mark quite rightly pointed out, it's probably specific to the actual circuit and models being used - maybe some improvement has been made. Not sure why you have software releases tied to specific machines - normally you'd have the software accessed over the network, which makes things much more flexible.

    So it's not really possible to diagnose the cause of the convergence failure without the circuit and the PDK; since it's solved using a later version of MMSIM, I'd suggest you use that rather than waste energy trying to understand why this old version struggles with that specific case.

    Regards,

    Andrew.

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