POSET timing and its application to the synthesis and verification of gate-level timed circuits


This paper presents a new algorithm for timed state-space exploration, POSET timing, POSET timing improves upon geometric methods by utilizing concurrency and causality information to dramatically reduce the number of geometric regions needed to represent the timed state space. The utility of POSET timing is illustrated by its application to the automatic synthesis and verification of gate-level timed circuits. Timed circuits are a class of asynchronous circuits that incorporate explicit timing information in the specification which is used throughout the synthesis procedure to optimize the design. Using POSET timing, our synthesis procedure derives a timed circuit that is hazard-free. The circuit uses only basic gates to facilitate the mapping to semi-custom components, such as standard-cells and gate-arrays. The resulting gate-level timed circuit implementations are 30%-40% smaller and 30%-50% faster than those produced using other asynchronous design methodologies. This paper also demonstrates that timed designs can be smaller and faster than their synchronous counterparts. The POSET timing algorithm cannot only efficiently verify our synthesized circuits but also a wide collection of large, highly concurrent timed circuits and systems that could not previously be verified using traditional techniques.