Reliable State Retention-Based Embedded Processors Through Monitoring and Recovery

State retention power gating and voltage-scaled state retention are two effective design techniques, commonly employed in embedded processors, for reducing idle circuit leakage power. This paper presents a methodology for improving the reliability of embedded processors in the presence of power supply noise and soft errors. A key feature of the method is low cost, which is achieved through reuse of the scan chain for state monitoring, and it is effective because it can correct single and multiple bit errors through hardware and software, respectively. To validate the methodology, ARM^® Cortex™-M0 embedded microprocessor (provided by our industrial project partner) is implemented in field-programmable gate array and further synthesized using 65-nm technology to quantify the cost in terms of area, latency, and energy. It is shown that the proposed methodology has a small area overhead (8.6%) with less than 4% worst-case increase in critical path and is capable of detecting and correcting both single bit and multibit errors for a wide range of fault rates.