A generalized modular redundancy scheme for enhancing fault tolerance of combinational circuits

• A generalized modular redundancy (GMR) scheme is proposed.
• GMR is a generalization of the well known triple modular redundancy (TMR) scheme.
• Some output combinations from a single or multiple outputs are protected.
• Protected output combinations cover a given threshold (e.g. 90% of combinations).
• Remarkable area overhead savings in addition to improved reliability are achieved.

Nano-scale devices are continuously shrinking, operating at lower voltages and higher frequencies. This makes them more susceptible to environmental perturbations and distinguished by their high dynamic fault rates. Redundancy techniques are widely used to increase the reliability of combinational logic circuits. In this work, soft error reliability is improved by using such techniques, and based on probability of occurrence for combinations at the outputs of circuits. A generalized modular redundancy scheme to enhance the reliability of combinational circuits is proposed. Additionally, several aspects regarding the application of this scheme are explored. This comprises types of redundant modules, complexity of voters and single versus multiple outputs protection. Also, a methodology for applying the generalized modular redundancy scheme is developed. Reliability analysis for various benchmarks from the LGSynth91 suite shows that the proposed methodology can achieve reliability figures higher than that of triple modular redundancy. In general, significant overhead savings are accomplished in addition to that superior reliability.