Fault-tolerant analogue filtering based on triplication

Tolerance to a single fault can be achieved by triplicating the system, including the sensor if desired, and including at the output a decision-circuit that is the analogue-circuit equivalent of the majority voting function in digital fault-tolerant systems. This paper shows that a median operation can be used to give fault tolerance. The ability of the system to correct for a single catastrophic fault is established. Also it is demonstrated that the effects of component tolerances on nonfaulty channels can be mitigated. An effect of this method is that small switching nonlinearities can be introduced into the output waveform due to the real time action of the median decision circuit.<>