Fault simulation and testing of an OTA biquadratic filter

We examine the testing and fault simulation of an analog operational transconductance amplifier (OTA) biquadratic filter. Catastrophic as well as parametric deviation faults are considered. We determine if the simulated faults are detectable by comparing the output voltage from the fault-free case with each of the faulty cases. We also compare the fault coverage obtained with this voltage verification test versus the faults detectable with supply current monitoring tests. A simple bound is found for the detection of catastrophic faults in the presence of parametric variations. This bound is based on selecting the minimum comparator threshold for comparing the CUT output with the reference signal. As this threshold approaches the peak output deviation due solely to parametric variations, no additional catastrophic faults can be detected using the voltage checking and supply current tests