iEDCL: Streamlined, False-Error-Free Error Detection and Correction Scheme in a Near-Threshold Enabled 32-bit Processor

This article presents internal error detection, correction, and latching (iEDCL), a designer-friendly, fully functional error detection and correction (EDAC) approach tailored for energy-efficient near-threshold systems capable of tolerating variations. It embeds error detection (ED), correction, and latching circuits within a flip-flop (FF) with an additional 15 transistors to monitor critical paths. Notably, iEDCL’s error-aware capability remains stable despite clock latency and parasitic effects, relieving designers of extensive involvement and eliminating false errors. iEDCL is automatedly implemented in an ARM Cortex-M0 processor at 55 nm without extra architecture modifications, incurring only a 6.78% area overhead. An adaptive voltage scaling (AVS) loop enables automatic operation, achieving high energy efficiency beyond the point of the first failure while maintaining a predefined error rate. Measurement results obtained from different dies at various temperatures demonstrate significant energy savings achieved by the iEDCL processor, with up to 16.9% and 49.1% reductions compared to critical baseline and signoff designs, respectively, while maintaining a 5% error rate at a 16 MHz frequency. To the best of our knowledge, this article presents one of the first FF EDAC implementations fully operational without potential false errors at near-threshold voltages while enhancing energy efficiency.

I. Introduction

The increasing need for energy-efficient digital circuits, driven by the widespread use of the Internet of Things (IoT) devices and wearables, has introduced challenges stemming from the inherent trade-off between limited on-chip energy resources and essential speed [1], [2]. Near-threshold operation has been proposed to mitigate this, offering a balance between performance and energy consumption. However, this approach introduces increased path delays due to variability in process, voltage, temperature, and aging effects, alongside design margins instituted for reliability [3]. Although these margins ensure reliable low-voltage operation, they negate some of the energy savings achieved in this regime.