Comparison of two approaches to improve functional BIST fault coverage

Two approaches to improve the fault coverage of functional logic BIST in digital circuits are proposed and investigated. The first approach is based on introducing of additional test points. An experimental tool set is developed for fast evaluation of the number of control points that is needed to achieve 100% fault coverage for the given functional test sequence. A novel algorithm is proposed to minimize the number of control points. The second approach is based on complementing the functional test with additional deterministic test patterns. The pros and cons of both approaches are highlighted and discussed.