Use of circuit redundancy to increase system reliability

FOR A GIVEN CLASS OF DEVICES, a given mode of packaging and a given operational environment, it can be shown that there exists an optimum circuit design, which corresponds to a maximum attainable reliability1. To obtain greater reliability beyond this optimum point, redundancy can be applied at the information, system, sub-system, circuit or component level2. This paper will be concerned with redundancy applied at the circuit and component levels wherein the reserve element are connected in such a way that failure of a component does not affect the operation of the system.