iRazor: Current-Based Error Detection and Correction Scheme for PVT Variation in 40-nm ARM Cortex-R4 Processor

This paper presents iRazor, a lightweight error detection and correction approach, to suppress the cycle time margin that is traditionally added to very large scale integration systems to tolerate process, voltage, and temperature variations. iRazor is based on a novel current-based detector, which is embedded in flip-flops on potentially critical paths. The proposed iRazor flip-flop requires only three additional transistors, yielding only 4.3% area penalty over a standard D flip-flop. The proposed scheme is implemented in an ARM Cortex-R4 microprocessor in 40 nm through an automated iRazor flip-flop insertion flow. To gain an insight into the effectiveness of the proposed scheme, iRazor is compared to other popular techniques that mitigate the impact of variations, through the analysis of the worst case margin in 40 silicon dies. To the best of the authors' knowledge, this is the first paper that compares the measured cycle time margin and the power efficiency improvements offered by frequency binning and various canary approaches. Results show that iRazor achieves 26%-34% performance gain and 33%-41% energy reduction compared to a baseline design across the 0.6- to 1-V voltage range, at the cost of 13.6% area overhead.