Multi-output functional decomposition with exploitation of don't cares

Abstract

Functional decomposition is an important technique in logic synthesis, especially for the design of lookup table based FPGA architectures. We present a method for functional decomposition with a novel concept for the exploitation of don't cares thereby combining two essential goals. The minimization of the number of decomposition functions in the current decomposition step and the extraction of common subfunctions for multi-output Boolean functions. The exploitation of symmetries of Boolean functions plays an important role in our algorithm as a means to minimize the number of decomposition functions not only for the current decomposition step but also for the (recursive) decomposition algorithm as a whole. Experimental results prove the effectiveness of our approach.