Integrated logic synthesis using simulated annealing

Conventional logic synthesis flows are composed of three separate phases: technology independent optimization, technology mapping, and technology dependent optimization. A fundamental problem with such a three-phased approach is that the global logic structure is decided during the first phase without any knowledge of the actual technology parameters considered during later phases. Although technology dependent optimization algorithms perform some limited logic restructuring, they cannot recover from fundamental mistakes made during the first phase, which often results in non-satisfiable solutions. In this paper, we present a method for integrating the three synthesis phases using an annealing algorithm as optimization framework. The annealing-based search is driven by a complex objective function, combining both technology independent as well as technology dependent optimization criteria. Our experimental results shown that, on average, the presented approach can improve the area and delay of circuits optimized with script rugged of SIS by 11.2% and 32.5% respectively.