Inhomogeneous cellular automata for weighted random pattern generation

Weighted random pattern testing methods produce higher fault coverage with shorter test lengths than random pattern testing methods. Here we present the weighted cellular automaton (WCA), an inhomogeneous cellular automaton that generates weighted random patterns on a test per clock basis. The WCA is a complete automaton that contains no external weighting logic and no multiplexers between flip-flop outputs and the circuit under test that add to critical path delays. Since the structure is based on cellular automata there are no complex routing problems. We also give a design algorithm, WCARGO, that automatically generates WCA from an ordered set of weights