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 [Spectre] Extracting model parameters for each Monte-Carlo iteration 

Last post Wed, Feb 5 2014 8:33 AM by gilsoriano. 2 replies.
Started by gilsoriano 29 Jan 2014 02:55 AM. Topic has 2 replies and 3308 views
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  • Wed, Jan 29 2014 2:55 AM

    • gilsoriano
    • Not Ranked
    • Joined on Wed, Jan 29 2014
    • Madrid, Madrid
    • Posts 2
    • Points 25
    [Spectre] Extracting model parameters for each Monte-Carlo iteration Reply

    Dear wizards,

     

    I need help to extract information about model parameters for each Monte-Carlo iteration in a Spectre simulation.

     The scenario is as follows:

    • Several Monte-Carlo iterations of a transient. 
    • The netlist contains bsim4-based models.
    • Mismatch parameters are extracted to a file via montecarlo parameters: savemismatchparams, mismatchscalarfile and mismatchparamfile.
    • I'm using Cadence-Spectre 5.1.4.

    For now, I have circumvented the issue by adding a line just before the transient analysis:

       paramInfo info what=all where=file file="MC_MODEL_PARAM" save=all

    it does what I want but it has two drawbacks:

    1. It slows down simulations A LOT.
    2. It appends all the model parameters one after the next one, for each MC iteration, in the same file.

    Basically, I got the problem solved, but I would be interested in knowing whether it can be done in a similar way as mismatch parameters (which results in different files for each MC iteration)

     

     Thanks for your help!

     

    Cheers,

    Carlos

    • Post Points: 20
  • Thu, Jan 30 2014 5:59 AM

    Re: [Spectre] Extracting model parameters for each Monte-Carlo iteration Reply

    Carlos,

    If you use what=models  it will save less information. Secondly, by using where=rawfile, it would save into the psf directory - and that way the data is organized by iteration number. It's binary, but easily processed using OCEAN functions.

    Regards,

    Andrew.

    • Post Points: 20
  • Wed, Feb 5 2014 8:33 AM

    • gilsoriano
    • Not Ranked
    • Joined on Wed, Jan 29 2014
    • Madrid, Madrid
    • Posts 2
    • Points 25
    Re: [Spectre] Extracting model parameters for each Monte-Carlo iteration Reply

    Andrew,

     thanks a lot for your help. I have used what=models and what=inst to relax the amount of information to be saved, as well as where=rawfile. I tinkered around with data but I'm still experiencing problems.

    I would like to process the MC data into MATLAB and then stumbled upon Spectre/RF MATLAB library, which looks great. I'm able to run the cds_srr command, however I'm not getting the results expected.

    The picture of my simulation structure is as follows:

    .
    `-- monteCarlo
        |-- MC3_separate
        |   |-- MC3-001
        |   |-- MC3-002
        |   |-- MC3-003
        |   |-- MC3-004
        |   |-- MC3-005
        |   `-- MC3-006
        `-- params
     
    • In the first level (.) I have the netlist *.scs files of both the testbench and the top design.
    • ./montecarlo Contains the results of the simulation of the testbench. At this level I can find both latest transient analysis and parameters (inst, in this particular case): TRAN1.tran and paramInfo.info. Then, two more files appear: MC3_TRAN1.montecarlo and MC3_paramInfo.montecarlo. I guess they are the files that point to the rest of MC simulations which are in the MC3_separate subfolders. Finally, logFile (attached, as well) is the file which MATLAB reads to know which files to evaluate.
    • ./params I have all the MC parameters specified in testbench file (which is attached in this post). 
    • ./MC3_separate contains all the MC runs specified. Inside the subfolder I can find both transient and paramaters information for each run.

    The problem arises whenever I try to load my data in MATLAB. cds_srr(dirname) is unable to find the MC simulations, even though they appear in logFile (to whom folder I point to via dirname). I can only access to the latest transient and parameter info files: TRAN1.tran and paramInfo.info. I have noticed that changing from psfbin to sst2 exporting options makes montecarlo simulations appear when calling cds_srr. However I'm bogged down again when trying to access this simulation: it is empty.

    To summarize everything up, whenever I run cds_srr I'm not able to load MC simulations. 

     In case you need further information do not hesitate to ask.

     Thanks a lot for your help.

     Regards,

    Carlos 

    • Post Points: 5
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Started by gilsoriano at 29 Jan 2014 02:55 AM. Topic has 2 replies.