Functional enhancements of TMR for power efficient and error resilient ASIC designs

Progressive technology scaling raises the need for efficient VLSI design methods facing the increasing vulnerability to permanent physical defects, while considering power efficiency of resulting circuit implementations at the same time. Triple Modular Redundancy (TMR) represents a common method to encounter reliability problems, but has the drawback of increased area and power consumption. This work introduces a Low Power Redundant (LPR) design solution that targets the power penalty of TMR implementations. This is done by enhanced and new functional runtime capabilities for error detection and operation control. By exploiting the inherent modularity and parallelism of TMR, the LPR solution applies additional control logic to switch dynamically between compare phases (to indicate faults and their locations) and parallel operation (with reduced operation frequency). This allows power optimized circuit operation with full support for the treatment of permanent faults. Simulation results on different ALU implementations show a decrease of power consumption of up to 60 % compared to conventional TMR. Furthermore, different strategies for the switching between operation modes are introduced that enable power efficient system operation in the presence of permanent physical defects. Moreover, significant reliability improvements are also achieved due to the adaptive use of the redundant modules.