Low-Cost Scan-Chain-Based Technique to Recover Multiple Errors in TMR Systems

In this paper, we present a scan-chain-based multiple error recovery technique for triple modular redundancy (TMR) systems (SMERTMR). The proposed technique reuses scan-chain flip-flops fabricated for testability purposes to detect and correct faulty modules in the presence of single or multiple transient faults. In the proposed technique, the manifested errors are detected at the modules´ outputs, while the latent faults are detected by comparing the internal states of the TMR modules. Upon detection of any mismatch, the faulty modules are located and the state of a fault-free module is copied into the faulty modules. In case of detecting a permanent fault, the system is degraded to a master/checker configuration by disregarding the faulty module. FPGA-based fault injection experiments reveal that SMERTMR has the error detection and recovery coverage of 100% and 99.7% in the presence of single and two faulty modules, respectively, while imposing negligible area and performance overheads on the traditional TMR systems.