Automatic Time-Redundancy Transformation for Fault-Tolerant Circuits

We present a novel logic-level circuit transformation technique for automatic insertion of fault-tolerance properties. Our transformation uses double-time redundancy coupled with micro-checkpointing, rollback and a speedup mode. To the best of our knowledge, our solution is the only technologically independent scheme capable to correct the multiple bit-flips caused by a Single-Event Transient (SET) with double-time redundancy. The approach allows soft-error masking (within the considered fault-model) and keeps the same input/output behavior regardless error occurrences. Our technique trades-off the circuit throughput for a small hardware overhead. Experimental results on the ITC'99 benchmark suite indicate that the benefits of our methods grow with the combinational size of the circuit. The hardware overhead is 2.7 to 6.1 times smaller than full Triple Modular Redundancy (TMR) with double loss in throughput. We do not consider configuration memory corruption and our approach is readily applicable to Flash-based FPGAs. Our method does not require any specific hardware support and is an interesting alternative to TMR for logic-intensive designs.