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Peak and average IR drop analysis mode

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Hello,

I am not sure about what means peak and average IR drop mode analysis in Encounter. What of these two analysis modes should be considered for power plan optimization?

I have a small block design (5K gates) operating at very low frequency (640 KHz) and there is a big difference between the results of these two analysis modes:

  • worst IR drop average analysis: 9.8035e-05 v

  • worst IR drop peak analysis: 4.3088e-01 v

Is average analysis frequency dependent? But voltage drop is not event dependent and so can cause timing problems also at low frequencies?

Thanks in advance.

 


Originally posted in cdnusers.org by clsantos
Parents

  • Hi Clsantos,

    Coming back to the discussion earlier, power and IR drop are not the same. In your case, the average power is very low because of very long period. However, very low average power means very low "average IR drop", but it does not imply anyting on peak IR.

    I think it is like this. Your design has to pass average IR drop by a margin or else your dynamic IR drop will fail. Average IR drop is still useful as it is fast to run, and is the only information you have when you do power planning.

    Regards,
    Eng Han


    Originally posted in cdnusers.org by EngHan
Reply

  • Hi Clsantos,

    Coming back to the discussion earlier, power and IR drop are not the same. In your case, the average power is very low because of very long period. However, very low average power means very low "average IR drop", but it does not imply anyting on peak IR.

    I think it is like this. Your design has to pass average IR drop by a margin or else your dynamic IR drop will fail. Average IR drop is still useful as it is fast to run, and is the only information you have when you do power planning.

    Regards,
    Eng Han


    Originally posted in cdnusers.org by EngHan
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