Redundancy identification and removal based on implicit state enumeration

The knowledge of the state transition graph (STG) of a sequential circuit helps in generating test sequences and identifying redundancies. The application of algorithms to the identification and removal of redundancies is reported. This strategy is based on traversing the STG of the given circuit and then performing redundancy identification using the reachability information calculated by the traversal. This method considers one candidate redundancy at a time, in an order that tries to minimize the total processing time. Substantial area and delay reductions are achieved. Experiments show that for many circuits 100% of the sequentially redundant faults can be eliminated in very reasonable amounts of time