DARA: A Low-Cost Reliable Architecture Based on Unhardened Devices and Its Case Study of Radiation Stress Test

A microprocessor with an architectural redundancy to achieve high dependability is designed and manufactured to explore the effectiveness of tolerating soft errors without circuit hardening. The processor architecture is based on a modularized pipeline which contains several functionalities to facilitate a real-time error detection and a fast roll-back recovery. As a further extension for a possible increase of hard errors in the future technology, an energy-effective coverage of hard errors by dynamically adapting the redundancy between a dual and a triple module is also included in the processor. A radiation stress test result indicates that the designed redundant but unhardened processor can successfully achieve the same dependability as a hardened processor. Our synthesis and layout results show that radiation hardened circuits increase processor hardware area by 71% and power by 28%, respectively. It is thus possible to use the architectural redundancy instead of circuit hardening to achieve a cost-effective reliability, as suggested by these factors.