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Liberate Characterization - Errors with encrypted PDK Model file

manpmanp

Hi 

I am trying to perform power and timing characterization on my custom cell designed and implemented in STM 28nm latest PDK. (Cadence Liberate version 16.1)

The problem is that the tool gets error when reading PDK model file due to having many lines encrypted in the lvt.scs file (as an include file in corner.scs) and the characterization flow stops!

The errors start appearing when I issue char_library after reading the spice nellists and model files

Any experience with this? Should it have any tool related solution??

  • Guangjun Cao

    Hi,

    First, 16.1 is way too old a version.

    Liberate relies on Spectre to parse the netlist. If all the files are correctly included, and the encrypted model can be successfully used by Spectre, you should have issues with Liberate.

    So, please check with your PDK team about the settings for models. Also, you may try to use set_var tmpdir <full_path> to same the decks. When Liberate fails, go into one of the sub-directory, open the sim.sp to check if all models have been called.  Then, run spectre on this sim.sp to debug what are missing.

    Regards,

    Guangjun

  • manpmanp
    in reply to Guangjun Cao

    Thanks for your reply!

    I solved it by a trick. almost in every material provided bu cadence (RAK and liberate user guide), the model file is read along the cell netlist.

    Although this provides a global model for the characterizer, not reading the model is not dangerous at all.

    So, what I did was these steps:

    1- set_var extsim_model_include ${MODEL_FILE}

    2- read ONLY cell netlist

    3- char_library -extsim spectre -cells ${cells} -thread ${THREAD} 

    => it results in: "*Info* No global model has been read in. Will expect model defined inside instance."

    but it is not dangerous and works as it should.

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