Exploration of switching activity behavior of addition algorithms

Total energy consumption of a micro-architecture directly depends on the switching factors of the internal nodes. Weinberger and Ling are the most widely used binary addition algorithms that are used in microprocessor adders. In this paper, the switching activity behaviors of those well known addition recurrence structures are explored. The formulae for estimation of switching activity rates of signals given the probabilities of input signals are derived. The results reveal that the preference of one addition algorithm to other one in terms of switching factors depends on the statistical properties of the input signals as well. The addition algorithms are examined on Kogge-Stone structure and it is possible to save energy up to 20% by selection of the proper addition algorithm in 64-bit adders.