On Reducing Circuit Malfunctions Caused by Soft Errors

Soft errors due to radiation are expected to increase in nanoelectronic circuits. Methods to reduce system failures due to soft errors include use of redundancy and making circuit elements robust such that soft errors do not upset signal values. Recent works have noted that electronic circuits have partial intrinsic immunity to soft errors since single event upsets on a large percentage of signal lines do not cause errors on circuit outputs. Using ISCAS-89 benchmark circuits we present experimental evidence that the partial immunity to single event upsets is in most cases due to redundancy in the circuits and thus immunity to soft errors may not be available in irredundant circuits. Thus goals on immunity to soft errors may not be achievable in highly optimized circuits without adding circuit redundancy and/or relaxing the requirements on system failures due to soft errors.