Code disjoint self-parity combinational circuits for self-testing, concurrent fault detection and parity scan design

In this paper it is shown how an arbitrary n-tupel of m-ary Boolean functions can be systematically implemented as a code-disjoint self-testing combinational circuit. This is achieved by the use of a parity bit of the inputs and a parity bit of the outputs, a second additional output and of one or more replicates of a selected part of the monitored circuit. The parity bit of the outputs and the functional bits are thus jointly designed rather than in separation. The circuit can be used in test mode, in scan-test mode if it is the combinational part of a sequential circuit, and in normal operation mode for concurrent fault detection. In normal on-line operation, faults may be detected with some degree of latency