Runtime variability sources, such as bias temperature instability (BTI) and supply voltage fluctuation affect both timing and functionality of the flip-flops inside a VLSI circuit. In this paper, we propose… Click to show full abstract
Runtime variability sources, such as bias temperature instability (BTI) and supply voltage fluctuation affect both timing and functionality of the flip-flops inside a VLSI circuit. In this paper, we propose a method to improve the timing and reliability of the VLSI circuits by optimizing the flip-flops for resiliency against aging and supply voltage fluctuation. In the proposed selective reliability optimization method, we first extend the standard cell libraries by adding optimized versions of the flip-flops designed for better resiliency against severe BTI impact and/or supply voltage fluctuation. Then, we optimize the VLSI circuit by replacing the aging-critical and voltage-drop-critical flip-flops (VC) of the circuit with the reliability-optimized versions to improve the timing and the reliability of the entire circuit in a cost-effective way. The simulation results show that incorporating the optimized flip-flops in a processor can prolong the lifetime of the processor by 36.9% compared to the original design, which translates into better reliability. This is achieved with negligible leakage overhead (less than 0.1% on the processor) and no area overhead which facilitates the integration of the proposed method in the standard VLSI design flow.
               
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