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run() & monteRun()

imagesensor123

 Hi all,

     for the same simulation, i have two process. the first, i set my model to the mc section, and i launched a simulation by clicking the "netlist and run" icon, we can get the result1(output curves). the second i also started a simulation from tools->monte Carlo, after configure the form, i triggered the "run" from the analog statistical analysis menus. we will get another result2. in special case, if i set the startIter "1" and numIter "1", can we espect that the result2 is the same with the result1? in another word, we choose "mc" section , not "tm" section in a classic simulation( from ADE window directly), is it a monte carlo analysis (just for one time)? one more question, could we change distribution method during monte carlo analysis? i didn't find any entrance in the analog statistical form.

 welcome to any discussion!

regards,

zfeng

Parents

  • Without seeing your models, I can't really say what is different between the two sections. Typically though some design kits have the statistics block only enabled when you pick a section specifically for monte carlo, and also sometimes they then use subckt wrappers around the models which is needed to allow mismatch. In normal cases maybe they have a direct instantiation of the model, but for mismatch in monte carlo, you must have a parameterized model within a subckt. Doing that normally shouldn't cause a problem either, but it can cause a simulation penalty with other (non-Cadence) simulators, so sometimes foundries organise their models two ways to cope with that (even though it probably doesn't matter with spectre).

    Sometimes it's also because the typical, fast, slow models have hard values of all the model parameters, whereas the models used in the monte carlo sections are parameterized instead.

    All depends on how it's been organised by the model creators.

    Regards,

    Andrew.

Reply

  • Without seeing your models, I can't really say what is different between the two sections. Typically though some design kits have the statistics block only enabled when you pick a section specifically for monte carlo, and also sometimes they then use subckt wrappers around the models which is needed to allow mismatch. In normal cases maybe they have a direct instantiation of the model, but for mismatch in monte carlo, you must have a parameterized model within a subckt. Doing that normally shouldn't cause a problem either, but it can cause a simulation penalty with other (non-Cadence) simulators, so sometimes foundries organise their models two ways to cope with that (even though it probably doesn't matter with spectre).

    Sometimes it's also because the typical, fast, slow models have hard values of all the model parameters, whereas the models used in the monte carlo sections are parameterized instead.

    All depends on how it's been organised by the model creators.

    Regards,

    Andrew.

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