Static Test Compaction for Functional Test Sequences With Restoration of Functional Switching Activity

Test vector omission allows the length of a functional test sequence to be reduced without reducing its fault coverage. When a circuit is embedded in a design, the omission of test vectors from a functional test sequence for the circuit may result in a sequence that does not satisfy the functional constraints imposed by the design. This paper addresses this issue by developing a procedure that restores omitted test vectors in order to satisfy functional constraints. For the discussion in this paper, functional constraints are captured by the switching activity of the sequence before any test vectors are omitted from it. This is referred to as its functional switching activity profile. Experimental results demonstrate that the length of a sequence can be reduced even after restoration of omitted test vectors based on its functional switching activity profile.