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IR drop analysis

spach

hi

i want to know why we do power analysis at worst prarasitics, worst temperature, worst library, at high vdd

and we use the instance based power report form above conditions to run the ir drop at  worst prarasitics,

worst temperature, worst library, at worst or low  vdd ?

why can not we do the power analysis and IR analysis at low(worst) vdd?

thanks & regards

spach 

 

 

 

 

 

 

 

Parents

  • Hi Spach

    I am not sue what you are suggesting is correct. Power analysis and IR drop analysis need to be run at the same PVT conditions. What you really care about is impact of IR drop on timing, and for that you need to run two runs at different PVT conditions.

    Setup violation could happen when data signal is late. That happens at high temp, low voltage (see in table below) as both slow down devices. Hold violation could happen when data signal is early, that happens at low temp, high voltage where devices are at their fastest. So you run libgen, powerMeter and VoltageStorm at FF corner and feed the result into STA for Hold analysis. You also run libgen, powerMeter and VoltageStorm at SS and feed the results to STA for Setup anslysis.


                                  Low Voltage                     Typical Voltage            High Voltage
     ----------------------------------------------------------------------------------------------------------------------------------
    Low Temp                                                                                     FF: IR drop-hold
                                 
    Typical Temp                                                      Typical

    High Temp              SS: IRdrop-setup                                                


    I also found this posting which you might find interesting:
    http://www.cadence.com/Community/forums/p/1018/1021.aspx

    Thanks
    Mohammad

Reply

  • Hi Spach

    I am not sue what you are suggesting is correct. Power analysis and IR drop analysis need to be run at the same PVT conditions. What you really care about is impact of IR drop on timing, and for that you need to run two runs at different PVT conditions.

    Setup violation could happen when data signal is late. That happens at high temp, low voltage (see in table below) as both slow down devices. Hold violation could happen when data signal is early, that happens at low temp, high voltage where devices are at their fastest. So you run libgen, powerMeter and VoltageStorm at FF corner and feed the result into STA for Hold analysis. You also run libgen, powerMeter and VoltageStorm at SS and feed the results to STA for Setup anslysis.


                                  Low Voltage                     Typical Voltage            High Voltage
     ----------------------------------------------------------------------------------------------------------------------------------
    Low Temp                                                                                     FF: IR drop-hold
                                 
    Typical Temp                                                      Typical

    High Temp              SS: IRdrop-setup                                                


    I also found this posting which you might find interesting:
    http://www.cadence.com/Community/forums/p/1018/1021.aspx

    Thanks
    Mohammad

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