Switching activity calculation of VLSI adders

Using exact switching activity rates at all internal nodes when calculating energy of digital circuits is believed to result in improved accuracy over to the use of average switching activity.We compare the two approaches in the case of the Kogge-Stone adder implemented with Weinberger and Ling addition recurrences. The difference between the two is less than 4%.Further we examined the accuracy of the energy/delay estimation technique when using exact and average switching activities in 65 nm, 45 nm, 32 nm and 22 nm technology nodes. Even then the worse case error in estimating energy is under 15% at 22 nm technology node for 64-bit Kogge-Stone adder. The error in delay estimation is less than 6% for all the nodes. Our finding is that using average switching activity does not yield large errors while simplifying the estimation process greatly.