Diagnosis of multiple stuck-at type faults and bridge faults in combinational circuits with redundant wires

Abstract

Behavior of a combinational circuit under the presence of a multiple stuck-at type fault and/or bridge faults, is analyzed. The circuit is assumed to be made up of AND, NAND, OR, NOR, and NOT gates, for simplicity of presentation of this paper. There are no other restrictions on the circuit structure. An algorithm is developed to enumerate different types of paths in the circuit, to determine a set of the primary input combinations to sensitize each path according to a well defined path sensitizing criterion, and finally to obtain a set of test patterns with a diagnostic resolution to locate all detectable components of the multiple fault and/or the bridge-faults present in the circuit. The last part of the algorithm builds a fault dictionary for the circuit under test. A theory is presented to prove the completeness of the diagnostic resolution of the obtained test-set. The theory is extended to show how a larger test-set obtained from the same algorithm can diagnose all multiple faults and/or bridge-faults in the circuits that contain undetectable faults and redundant wires.