A Sub-nW Fully Integrated Switched-Capacitor Energy Harvester for Implantable Applications

Abstract

A sub-nW fully integrated switched-capacitor energy harvester for implantable applications is presented in this paper. Unlike conventional cascaded scheme where harvested current flows through all stages, with recursive current injection topology, harvested current is directly injected to each stage of recursive voltage booster, significantly enhancing harvesting efficiency. An automated conversion ratio and switching frequency control scheme are also proposed to enable maximum power point tracking with minimal overhead. The proposed harvester achieves >50.4% efficiency while harvesting >0.126 nW from 100mV source.