Comparison of test pattern decompression techniques

Test pattern decompression techniques are bounded with the algorithm of test pattern ordering and test data flow controlling. Some of the methods could have a more sophisticated sorting algorithm, some of the methods may be supported by fault simulation and some can work without any information about the quality of previously generated lest patterns. The differences between the decompression techniques cause that the efficiency of the automata is not comparable and the published results do not give us any idea of the best choice of decompressing automaton. We have performed experiments, in which we have studied the degradation of random input stimuli by the decompression automata (DA) used by different authors. We have found that a medium percentage of the (n, r) exhaustive test set created on the DA outputs after stimulating the DA inputs with a given number of random pattern is correlated with the DA efficiency. This statement has been verified by experiments with ISCAS circuits.