Circuit lines for guiding the generation of random test sequences for synchronous sequential circuits

A procedure proposed earlier for improving the fault coverage of a random primary input sequence modifies the input sequence so as to avoid repeated synchronization of state variables. We show that in addition to the values of state variables, it is also important to consider repeated setting of other lines to the same values. A procedure and experimental results are presented to demonstrate the improvements in fault coverage of random primary input sequences when the values of selected lines are considered.