Self-powered micro-watt level piezoelectric energy harvesting system with wide input voltage range

Abstract

This paper presents a micro-watt level energy harvesting system for piezoelectric transducers with a wide input voltage range. Many such applications utilizing vibration energy harvesting have a widely varying input voltage and need an interface that can accommodate both low and high input voltages in order to harvest as much energy as possible. The proposed system consists of two rectifiers, both implemented as negative voltage converters followed by active-diodes, and three switched-capacitor DC-DC converters to either step-up or step-down and regulate to the target voltage. The system has been implemented in a 0.18m CMOS process and the chip measures 3mm(2). Measurements show a low voltage drop across the rectifiers and high peak power efficiency of the DC-DC converters (68.7-82.2%) with an input voltage range of 0.45-5.5V for the complete system. Used standalone, the DC-DC converters support input voltages between 0.5 and 11V while maintaining an output voltage of 1.8V at an output power of 16.2W. The ratio of each converter is selectable to be either 1:2, 1:3, or 1:4.