PLA-based regular structures and their synthesis

Two regular circuit structures based on the programmable logic array (PLA) are proposed. They provide alternatives to the widely used standard-cell structure and have better predictability and simpler design methodologies. A whirlpool PLA is a cyclic four-level structure, which has a compact layout. Doppio-ESPRESSO, a four-level logic minimization algorithm, is developed for the synthesis of Whirlpool PLAs. A river PLA is a stack of multiple output PLAs, which uses river routing for the interconnections of the adjacent PLAs. A synthesis algorithm for river PLAs uses multilevel logic synthesis, simulated-annealing, and ESPRESSO targeting a combination of minimal area and delay.