PSOP decomposition for EXOR-based synthesis

In the classical CMOS technology, EXOR gates are considered expensive and impractical. Recently, the growing relevance of cryptography-related applications and emerging technologies has revived the interest in EXOR gates. In this contexts, it is therefore important to consider network representations that assume EXOR gates explicitly, since the non-EXOR gates have, in general, a higher cost than EXOR ones. As a result, the widely adopted And-Inverter Graph (AIG) logic networks, have recently evolved into the new XOR-AND Graph (XAG) multi-level logic representation, and the logic synthesis on XAGs mainly aims at reducing the number of AND nodes. In general, we call EXOR-based synthesis the synthesis methods that minimize the non-EXOR gates in a Boolean circuit. Projected Sum Of Product, PSOP, decomposition is an EXOR based technique that can be applied to any Boolean function as a very fast pre-processing step for further minimizing the circuit area in standard logic synthesis. In this paper, we exploit PSOP decomposition in EXOR-based synthesis. The experimental results validate the proposed pre-processing method in EXOR-based synthesis, showing an interesting gain in area, within the same time limit.