Timing Path-Driven Cycle Cutting for Sequential Controllers

Power and performance optimization of integrated circuits is performed by timing-driven algorithms that operate on directed acyclic graphs. Sequential circuits and circuits with topological feedback contain cycles. Cyclic circuits must be represented as directed acyclic graphs to be optimized and evaluated using static timing analysis. Algorithms in commercial electronic design automation tools generate the required acyclic graphs by cutting cycles without considering timing paths. This work reports on a method for generating directed acyclic circuit graphs that do not cut the specified timing paths. The algorithm is applied to over 125 benchmark designs and asynchronous handshake controllers. The runtime is less than 1 second, even for even the largest published controllers. Circuit timing graphs generated using this method retain the necessary timing paths, which enables circuit validation and optimization employing the commercial tools. Additional benefits show these designs are on an average a third in size, operate 33.3% faster, and consume one-fourth the energy.