Test generation for SI asynchronous circuits with undetectable faults from signal transition graph specification
In this paper, we propose an approach to test pattern generation for Speed-Independent (SI) asynchronous control circuits. Test patterns are generated based on a specified sequence, which is derived from the specification of a target circuit in the form of a Signal Transition Graph (STG). Since the sequence represents the behavior of a circuit only with stable states, the state space of the circuit can be represented as reduced one. A product machine, which consists of a fault-free circuit and a faulty circuit, is constructed and then the specified sequence is applied sequentially to the product machine. A fault is detected when the product machine produces inconsistency, i.e., output values of a fault-free circuit and a faulty circuit are different, and the sequentially applied part of the sequence becomes a test pattern to detect the fault. We also propose a test generation method using an undetectable fault identification as well as the specified sequence. Since the reduced state space is a subset of that of a gate level implementation, test patterns based on a specification cannot detect some faults. The proposed method identifies those faults with a circuit topology in advance. BDD is used to implement the proposed methods efficiently, since the proposed methods have a lot of state sets and set operations. Experimental results show that the test generation using a specification achieves high fault coverage over single stuck-at fault model for several synthesized SI circuits. The proposed test generation using a circuit topology as well as a specification decreases execution time for test generation with negligible cost retaining high fault coverage.
testing si asynchronous circuits signal transition graph atpg