Qualifying Relative Timing Constraints for Asynchronous Circuits

Abstract

Relative Timing uses path based timing constraints to guarantee that a circuit conforms to its behavioral specification. Timing constraints are used to order signal transitions or events in a circuit through corresponding minimum and maximum delay timing constraints. A circuit may have multiple sets of constraints, each of which, when satisfied, can individually ensure functional correctness. This paper presents a framework to evaluate and rank relative timing constraint sets for a given circuit. The constraint sets are evaluated on the basis of robustness of the constraints and conflicts between constraints in the same set. The analysis is automated by building a tool. The paper applies the methodology and tool to optimize the extraction of relative timing constraints for delay insensitive timing models of asynchronous circuits. This is demonstrated using a burst-mode controller. The optimization leads to an average tool runtime reduction of 94%.