How to generate high quality tests for digital systems

A uniform approach for modeling faults and structure of digital systems is presented. Physical defects are modelled as parameters in generic Boolean differential equations. Solutions of the equations give the conditions called functional fault model at which defects are locally activated. The functional fault model can be regarded as a uniform interface for mapping faults from one system level to another, helping to carry out hierarchical test generation. For representing the system decision diagrams (DD) are used. Binary DDs represent logic level whereas register level DDs represent higher-level structures. Experiments have shown the feasibility and efficiency of the hierarchical method compared to the classical one-level stuck-at fault based approaches.