IR drop analysis

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

Thanks Mohammad

so for IR drop based STA for setup analysis i need to use the worst PVT conditions for power analysis and low vdd rail for IR drop analysis but power analysis at low VDD does not give the worst power consumption hence is it correct to run power analysis and IR analysis at worst PVT and low vdd rail. 

can any one explain how ir drop varies with power consumption and recommanded PVT conditions for power analysis and rail volltage for IR analysis?

thanks & regards

spach 

Yes, that is correct. If you are running IR drop to feed STA you do not need to run the worst power corner. Typically worst power is used to identify grid problems. For IR-drop aware timing you need to run according to the table I listed above.

 Thanks