Direct synthesis of timed asynchronous circuits

Abstract

This paper presents a new method to synthesize timed asynchronous circuits directly from the specification without generating a state graph. The synthesis procedure begins with a deterministic graph specification with timing constraints. A timing analysis extracts the timed concurrency and timed causality relations between any two signal transitions. Then, a hazard-free implementation of the specification is synthesized by analyzing precedence graphs which are constructed by using the timed concurrency and timed causality relations. The major result of this work is that the method does not suffer from the state explosion problem, achieves significant reductions in synthesis time, and generates synthesized circuits that have nearly the same area as compared to previous timed circuit methods. In particular, this paper shows that a timed circuit-not containing circuit hazards under given timing constraints-can be found by using the relations between signal transitions of the specification. Moreover, the relations can be efficiently found using a heuristic timing analysis algorithm. By allowing significantly larger designs to be synthesized, this work is a step towards the development of high-level synthesis tools for system level asynchronous circuits.