Design of self-testing and on-line fault detection combinational circuits with weakly independent outputs

In this article we propose a structure dependent method for the systematic design of combinational selftesting fault detection circuits that is well adapted to the arbitrarily chosen technical fault model. According to the fault model considered the outputs of the circuit are partitioned into different generally nondisjoint groups of weakly independent outputs. The parities of these groups of weakly independent outputs are compared in test mode as well as in normal operation mode with the corresponding predicted parities by use of a self-checking checker. For on-line detection, the hardware is in normal operation mode, and for testing, it is in test mode. In the test mode, these fault detection circuits guarantee a 100% fault coverage for single stuck-at-0/1 faults and a high fault coverage for arbitrary faults. In normal operation mode all technical faults considered will be detected possibly, with some degree of latency.