Testing Asynchronous Circuits: A Survey1

Asynchronous circuit design has been studied for decades, but it has only recently been feasible to construct large and eecient asynchronous systems. This paper surveys diierent techniques for checking whether an asynchronous circuit has fabrication defects. The inherent diierences between asynchronous and synchronous circuits, primarily that asynchronous circuits do not have a global clock, necessitate a review of the testing techniques used for synchronous circuits and a re-evaluation of the trade-oos involved. New methods that eeciently utilize the structure of asynchronous circuits are possible, most notably self-checking asynchronous circuits can be implemented with little or no circuit overhead.