On the Computation of Common Test Data for Broadside and Skewed-Load Tests

Skewed-load and broadside tests complement each other and allow higher delay fault coverage to be achieved for a standard-scan circuit that supports both types of tests. The difference between the two types of tests is mainly in the test application process. The input test data required for both of them are similar. This similarity is used in this work to compute compact input test data that can be used as a basis for forming both types of tests. It results in improved fault coverage compared to the use of broadside (or skewed-load) tests alone, and in reduced test data volume compared to the case where broadside and skewed-load tests are stored separately. Experimental results are presented using a procedure that accepts a test set of any type, and computes input test data suitable for the application of both types of tests. The procedure modifies the test data so as to compact it as well as increase the fault coverage. The procedure is applied to a broadside test set and to mixed test sets that consist of both types of tests.