Iterative-based minimization of unary 4-valued functions for current-mode CMOS realization

In this paper, we introduce an iterative-based algorithm for synthesis of near-minimal cost 4-valued unary functions realized using current-mode CMOS circuits. The cost of a circuit is measured in terms of the chip area needed. The introduced algorithm is used to construct a universal table that contains all 256 4-valued unary functions, their realizations, and their realized costs. Starting with a cost-table consisting of 2400 functions with their known published costs (seed costs), the algorithm generates new functions at reduced costs by using the P-mirror, N-mirror, SUM, P-switch or the N-switch as output operators. Experimental results indicate that there has been cost improvement in 227 of the 256 functions.