PROTEST: A Tool for Probabilistic Testability Analysis

The CAD-tool PROTEST (Probabilistic Testability Analysis) is presented. PROTEST estimates for each fault of a combinational circuit its detection probability which can be used as a testability measure. Moreover it calculates the number of random test patterns which must be generated in order to achieve the required fault coverage. It is also demonstrated that the fault coverage will increase and the necessary number of random patterns will drastically decrease, if each primary input is stimulated by test patterns having specific probabilities of being logical “1”. PROTEST uses this fact and determines for each input the optimal signal probability for a randomly generated pattern.