Design of an MTJ/CMOS-based Asynchronous System for Ultra-Low Power Energy Autonomous Applications

Most of today’s IoT-based computing systems offer an opportunity to build smarter systems for application areas such as healthcare monitoring and wireless sensor nodes. Since these systems are energy limited and remain idle for most of the time, they suffer from large leakage power dissipation. Another problem faced by such computing systems is sporadic power failures when employed with energy harvesters where the system loses its current state and needs long reinitialization time. To address these problems, this work combines asynchronous design techniques with nonvolatility to achieve ultra-low power operation during active mode and data retention during power failure. This paper first presents a detailed analysis of different implementations of volatile c-element and compares their performance in terms of power and delay. Then one of the implementations is selected for nonvolatile design of a hybrid c-element using emerging spin transfer torque–magnetic tunnel junction (STT–MTJ) technology which allows energy-efficient data retention during idle mode/power-off mode and during sudden power failures. Using this hybrid c-element, we design a novel nonvolatile weak conditioned half-buffer. The extensive analysis of these designs with different design metrics is performed at the circuit level using Synopsys HSPICE circuit simulator.