Adaptive subthreshold timing-error detection 8 bit microcontroller in 65 nm CMOS

Abstract

Subthreshold voltage operation enables digital systems to operate at ultra-low energy levels. However, as the voltage is reduced into subthreshold, the required safety margins become unrealistically large due to exponential dependencies. These margins can be addressed in a system by sensors, replica-path circuits, or timing error detection (TED). Each of these methods require additional energy overhead. TED is the only method that accounts for both global and local variations. This paper presents the first TED 8 bit microcontroller that is able to operate in subthreshold. The microcontroller uses adaptable EDS circuits to adjust to system-level constraints. It is built in 65 nm CMOS, uses 10.42 pJ/instruction, occupies an area of 50,200 µm2, and operates down to 300 mV.