An Efficient Fault Simulator for QDI 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 are usually obtained by introducing redundancies, that is, sacrificing the testability. So test frameworks such as fault simulator for synchronous circuits are not applicable for asynchronous circuits. In this paper we present an efficient fault simulator for template-based asynchronous circuits which is based on checking sequence of signals in templates. Our proposed fault simulator provides higher fault coverage by taking into consideration the detection of a special class of faults called premature firing faults without introducing any hardware redundancy in the designed circuit. Experimental results on a set of circuits have shown the effectiveness of the fault simulator.