A high-efficiency optimized bias-flip energy harvesting system for IoT applications

Abstract

This paper presents a high-efficiency optimized bias-flip energy harvesting system for Internet of Things (IoT) applications. The harvester consists of a piezoelectric transducer and an interface circuit. Unlike previous bias-flip harvesters, a piezoelectric transducer uses an optimized electrode structure instead of a monolithic electrode to reduce the internal capacitance of the piezoelectric transducer and increase the voltage flip efficiency and maximum output power. The optimized bias-flip harvester does not increase the inductor value or aspect ratio of flip switches to increase efficiency and does save chip area and system volume. While the interface circuit uses a switched-capacitor controller to control the gate-overdrive of the flip switches, employing the adiabatic technique reduces the power consumption of the switching in the control circuit by about 10%. Theoretical analysis of the electrode length effect on the voltage flip efficiency and output power has been performed. Theoretical analysis is confirmed by COMSOL and HSPICE simulations. The maximum output power of the proposed harvester is about 7.4 times the FBR and has superior performance compared to previously reported interface circuits.