SEU and SET fault injection models for fault tolerant circuits

In this paper we describe the fault injection models for the systems tolerant to the single event upsets (SEU) and single event transients (SET). The presented fault modelling approach is based on the random generated SEU faults in sequential logic and SET faults in combinational logic. The fault injection models for triple modular redundant (TMR) and dual modular redundant (DMR) circuits are developed in order to simulate the fault-tolerant systems. The analytical models for calculation of the probability of failure-free TMR and DMR circuits are defined too. To justify the reduced redundancy concept, the simulated and calculated probabilities of failure-free TMR and DMR circuits are presented and discussed. The obtained results show a better trade-off between hardware overhead and circuit failure-free probability of the DMR concept.