A Switched Capacitor Multiple Input Single Output Energy Harvester (Solar + Piezo) Achieving 74.6% Efficiency With Simultaneous MPPT

摘要

This paper presents an inductor-less switched capacitor based energy harvester, which can simultaneously harvest from 2 energy sources (Solar + Piezo). The proposed harvester employs maximum power point tracking algorithm, by changing the conversion ratios of the charge pumps for piezo and solar sources, and output voltage control by varying the switching frequency. The proposed MPPT algorithm can match the input impedance of two sources simultaneously. Implemented in 65nm CMOS, the proposed harvester can generate a fixed output between 1.8 and 2.5 V output while delivering 35 mu W to 70 mu W power with a peak power conversion efficiency of 74.6%.