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Liberate: Characterize integrated clock gating cell

djupdal

Hi.

I have just made a clock gating cell and would like to characterize it with liberate.  However, liberate does not seem to understand it is a clock gater (resulting .lib does not include "clock_gating_integrated_cell" anywhere).  Is there anything extra I need to do to characterize a clock gating cell, or should it work just like for any other cell?  Other cells, like NAND, NOR, FF etc are all correctly identified automatically when I characterize them.

Are there any examples I can look at which include clock gating cells?

Best regards, Asbjørn

Parents

  • Hi Asbjørn,

    'clock_gating_integrated_cell' attribute can be added using set_attribute command or defined in a user_data file. Since it does not affect the characterization or is not simulation-related, Liberate does not automatically add such attributes.

    Regards,

    Guangjun

  • in reply to Guangjun Cao

    Thanks, that was helpful. 

    I don't get any function specified for the output pin either.  Is that also something I should specify myself?

    I will do another characterization of my library now and see if I can get genus to recognize the clock gating cell when I specify the attribute manually.

    Regards,

    Asbjørn

  • in reply to djupdal

    Hi,

    clock-gating cells have a list of attributes at cell and pin levels. All need to be defined by users.

    Function of such cells is described by a statetable at cell level and state_function for output pins. 

    Please refer to Liberty User Guide that has some examples. if you already have a reference library, write out the user data file will the simplest way.

    Regards,

    Guangjun

Reply
  • in reply to djupdal

    Hi,

    clock-gating cells have a list of attributes at cell and pin levels. All need to be defined by users.

    Function of such cells is described by a statetable at cell level and state_function for output pins. 

    Please refer to Liberty User Guide that has some examples. if you already have a reference library, write out the user data file will the simplest way.

    Regards,

    Guangjun

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