On interconnecting circuits with multiple scan chains for improved test data compression

We show that when a scan design consists of interconnected circuits, test data volume reductions can be achieved by connecting the scan chains of adjacent circuits appropriately. We formulate this problem as a problem of finding a permutation of the scan chains of one circuit with respect to another so as to minimize the number of different scan vectors required for testing both circuits. We propose a procedure for solving this problem, and present experimental results.