Testing hyperactive faults in asynchronous circuits

Testing asynchronous circuits is a difficult task, because of two main reasons; first, the absence of a global clock does not allow the use of traditional test generation techniques used for synchronous circuits. Second, correct (i.e, hazard-free) operations of asynchronous circuits an usually obtained by introducing redundancies, that is, sacrificing the testability. The authors present an efficient test generator for asynchronous circuits which is based on a concurrent fault simulator. They also present an extension of the simulator which provides higher fault coverage by taking into consideration the detection of a special class of faults called hyperactive faults. Experimental results on a set of benchmarks has shown the effectiveness of the test generator, and proved that real circuits actually contain instances of such faults.