Generation of tenacious tests for small gate delay faults in combinational circuits

In this paper, we present a test for small gate delay faults in combinational circuits, called a tenacious test and describe a method for generating tenacious tests. We consider a single gate delay fault in a circuit on the assumption of that each gate has some appropriate gate delay. First, we introduce a tenacious test ⟨V1, V2⟩ for a small gate delay fault on line L. The tenacious test ⟨V1, V2⟩ can propagate the effect of a small gate delay fault at line L to primary outputs by the delay effect. Next, we present a method for generating tenacious tests by using a timed seven-valued calculus with consideration of delay of each gate in a circuit under test. Finally, experimental results are demonstrated for gate delay faults on ISCAS´85 benchmark circuits. Experimental results show that we can obtain tenacious tests for small gate delay faults with high fault coverage