Behavior of a radiation-immune CMOS logic family under resistive shorts

Previous researchers had developed a special family of CMOS logic circuits which uses additional feedback transistors to provide immunity to radiation-induced errors for space-borne electronics. It was originally speculated that these transistors, representing a form of redundancy, might provide additional benefits, such as greater tolerance of manufacturing defects. Instead, the authors work shows that the redundant transistors, because of the way in which they are used, increase the sensitivity of the circuitry to manufacturing defects which manifest themselves as resistive transistor shorts, such faults cause: (1) logic errors at the affected gate output; and (2) an increase in the signal transition delay. Furthermore, these transistors lead to higher levels of quiescent supply current, making the circuits more difficult to test using quiescent current (I/sub DDQ/) testing.