Generation of Mixed Test Sets for Transition Faults

Test sets that contain both broadside and skewed-load tests are important for achieving the highest possible delay fault coverage for standard-scan circuits. Both types of tests can be represented as 〈s₁, v₁, s₂, v₂ 〉, where s₁ and s₂ are states, and v₁ and v₂ are primary input vectors. To facilitate the generation of a mixed test set that contains both broadside and skewed-load tests, this paper associates with s₂ a property that can be used for estimating whether a skewed-load or a broadside test is more likely to exist with s₂ in its second pattern. This paper uses this property for guiding a test generation procedure to consider only one of the two test types for most of the target faults.