CMOS Indoor Light Energy Harvesting System for Wireless Sensing Applications: An Overview

Abstract : This paper presents an overview of the PhD thesis “CMOS indoor light energy harvesting system for wireless sensing applications”, whose main goal was designing a micro-power light energy harvesting system for indoor scenarios, addressing the challenges associated with this kind of environment. Light energy was taken in by using an amorphous silicon (a-Si) photovoltaic (PV) cell and conditioned using a switched-capacitor (SC) voltage converter, along with a maximum power point tracking (MPPT) capability. The MPPT method was the Fractional VOC, put into practice by using an asynchronous state machine (ASM) which automatically establishes and controls the clock signals’ frequency, thus controlling the switches of the voltage converter. To minimize the area of the SC section, MOSFET capacitors were used. A charge reusing scheme was proposed, so as to decrease the loss through the parasitic capacitance of their bottom plate. Laboratorial results, taken from a CMOS solid-state prototype, show that the proposed system can achieve better results than those in the present state of the art.