Functional and partially-functional skewed-load tests

Abstract

Functional broadside tests were defined to address overtesting that may occur with unrestricted scan-based tests. However, the fault coverage achievable by functional broadside tests is lower than the fault coverage achievable by unrestricted scan-based tests. It was observed that skewed-load tests can improve the fault coverage achievable by unrestricted broadside tests. Motivated by these observations, we define functional (and partially-functional) skewed-load tests to improve the fault coverage of functional broadside tests while attempting to curb overtesting. We present experimental results to demonstrate the ability of functional skewed-load tests to improve the fault coverage without exceeding the maximum switching activity of functional broadside tests (which is one indication of potential overtesting).