IDDQ testing of oscillating bridging faults in CMOS combinational circuits

I_DDQ testing has been shown to be an efficient way to test CMOS technology circuits when realistic failures, bridges among others, are considered. A particular group of bridging faults cause the circuit to oscillate because of unstable feedback. The authors focus on the evaluation of I_DDQ testability for these bridging faults. An electrical circuit model allows the analytic derivation of characteristics of the oscillating I_DD behaviour. it is shown that oscillating faults are testable by classical I_DDQ sensors. The knowledge of the ripple frequency and the maximum and minimum values of the oscillating I_DD current allows the characterisation of the I_DDQ levels, and it is useful in the design of choice of a current sensor in the general case