Use of Passive Redundancy in Electronic Systems

Circuit design predicated solely upon the premise of providing circuits with greater and greater immunity against component tolerances at some point results in an increase in catastrophic failure rates. Thus, circuits which are overdesigned to provide maximum protection against drift failures may actually contribute to a lower system reliability than do those circuits which are designed to operate with tighter component tolerances. These considerations lead to the conclusion that as systems grow in complexity or as reliability requirements are significantly increased for current equipment, a point is reached where further improvement in design procedures will not necessarily lead to further increases in system reliability. A way out of this dilemma appears to be the introduction of some form of redundancy on the component or circuit level in order to overcome the effects of the inevitable occurrence of catastrophic component failures. This paper discusses the application of redundancy techniques, of a nonadaptive and passive nature, to electronic circuits and systems.