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 〈s
₁
, v
₁
, s
₂
, v
₂
〉, where s
₁
and s
₂
are states, and v
₁
and v
₂
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 s
₂
a property that can be used for estimating whether a skewed-load or a broadside test is more likely to exist with s
₂
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.