DFT for improving the testability of parametric resistor faults in a strain gauge measurement circuit

This paper describes how equivalent fault analysis is used to formulate a DFT scheme for a strain gauge measurement circuit, consisting of a Wheatstone bridge and amplifier. The derivation of fault equivalence relationships benefit from the simplification of analyzing each subcircuit in isolation from the system. The error introduced by ignoring loading and coupling effects is shown to be small for the fault ranges considered. The DFT solution developed combined individual solutions to subcircuit fault equivalence. Experimental results obtained demonstrate the effectiveness and validity of the approach.