The influence of No Fault Found in analogue CMOS circuits

The most difficult fault category in electronic systems is the “No Fault Found” (NFF). It is considered to be the most costly fault category in, for instance, avionics. The relatively few papers in this area rarely deal with analogue integrated systems. In this paper a simple simulation model has been developed for a particular type of NFF, the intermittent resistive fault resulting from bad interconnections. Simulations have been carried out with respect to a CMOS operational amplifier under influence of NFFs, and the resulting behaviour under different fault conditions has been examined.