Test Wrapper Design and Optimization Under Power Constraints for Embedded Cores with Multiple Clock Domains

Even though many embedded cores contain several clock domains, most published methods for wrapper design have been limited to single-frequency cores. Cumbersome and invasive design techniques, such as insertion of test points, are needed to make these methods applicable to current-generation embedded cores. This paper presents a new method for designing test wrappers for embedded cores with multiple clock domains. The proposed 1500-compliant wrapper prevents clock skew and allows scan chains in different clock domains to shift test data at distinct clock frequencies, which enables a better control of power dissipation during test. We present an integer linear programming (ILP) model that can be used to minimize the core testing time under power constraints for small problem instances, and which can be combined with LP-relaxation to obtain lower bounds on the testing time for larger instances. We also present an efficient heuristic method that is applicable to large problem instances, and which yields the same (optimal) testing time as ILP for small problem instances.