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 How to get the loading capacitance of a certain instance by encounter? 

Last post Wed, May 22 2013 1:34 PM by BobD. 3 replies.
Started by qijianfei 22 May 2013 01:09 PM. Topic has 3 replies and 711 views
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  • Wed, May 22 2013 1:09 PM

    • qijianfei
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    • Joined on Wed, May 22 2013
    • Posts 3
    • Points 45
    How to get the loading capacitance of a certain instance by encounter? Reply

     Dear All,

     If I know the instant name and its output pin's name. How can I use encounter to get the loading capacitance of that pin? Which command should I use? 

     

    Thanks

    qijianfei

    • Post Points: 20
  • Wed, May 22 2013 1:24 PM

    • BobD
    • Top 25 Contributor
    • Joined on Fri, Jul 11 2008
    • Chelmsford, MA
    • Posts 247
    • Points 9,325
    Re: How to get the loading capacitance of a certain instance by encounter? Reply

    Here's an example: 

    report_property [get_nets [get_property [get_pins DTMF_INST/TDSP_CORE_INST/TDSP_CORE_GLUE_INST/i_962/Y] net_name]]

    total_capacitance_max_fall          | 0.006
    total_capacitance_max_rise          | 0.006
    total_capacitance_min_fall          | 0.006
    total_capacitance_min_rise          | 0.006
    wire_capacitance_max                | 0.002
    wire_capacitance_max_fall           | 0.002
    wire_capacitance_max_rise           | 0.002
    wire_capacitance_min                | 0.002
    wire_capacitance_min_fall           | 0.002
    wire_capacitance_min_rise           | 0.002 

    You can query individual values with get_property which should also accept specification of a -view:

    get_property -view default_analysis_view_hold [get_nets [get_property [get_pins DTMF_INST/TDSP_CORE_INST/TDSP_CORE_GLUE_INST/i_962/Y] net_name]] wire_capacitance_max 

    Hope this helps,
    Bob 

    • Post Points: 20
  • Wed, May 22 2013 1:33 PM

    • qijianfei
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    • Joined on Wed, May 22 2013
    • Posts 3
    • Points 45
    Re: How to get the loading capacitance of a certain instance by encounter? Reply

    Does this net capacitance include the input capacitances (gate capacitances) of the input pins connected with this output pin? 

    Thank you so much Bob.

    • Post Points: 20
  • Wed, May 22 2013 1:34 PM

    • BobD
    • Top 25 Contributor
    • Joined on Fri, Jul 11 2008
    • Chelmsford, MA
    • Posts 247
    • Points 9,325
    Re: How to get the loading capacitance of a certain instance by encounter? Reply
    I believe total_capacitance does include input pin cap(s), wire capacitance does not.
    • Post Points: 5
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Started by qijianfei at 22 May 2013 01:09 PM. Topic has 3 replies.