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Measurements >> Other Measurements >> internal power in .lib files
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Message started by Evgenii on Jun 16^th, 2008, 7:51am

Title: internal power in .lib files
Post by Evgenii on Jun 16^th, 2008, 7:51am

Hi!
I simulate internal power ("rise_power", "fall_power", internal power group in .lib format synopsys) for digital library cells. But i do it manually, w/o special tools like nanochar . In particular, i use internal function of spice simulator. In simplest cells (invs, buffs) the following assumption works:
Internal power = total power –C_load*VDD*VDD/2, where
total power = integral i_vdd(t) during rise/fall time for output signal* VDD
In some cases, fall_power is negative.
Results looks good as in an available sample file. But in complex cells (flip-flops for example), in sample .lib file internal power poorly depends from C_load, does not depend almost. I have different results, for big load capacitances (I use same templates) internal power exceeds ten times power, which presented in sample file.
?????
Thanks for help!