Multi-source energy harvesting for lightweight applications

Abstract

This thesis analyzes, designs and tests circuit topologies for simultaneous energy harvesting from solar and 915-MHz RF energy sources. An important design objective is to minimize system weight while maximizing output power and operating time for applications in the sub-170-mg and single-mW ranges. The resulting energy harvesting system uses a unique approach of categorizing the harvesters as primary and auxiliary harvesters due to the power levels of each in relation to the high load demand. This work results in a 162-mg supercapacitor-powered system capable of powering a 2-V load at up to approximately 2-3 mW and a 150-mg battery-powered system capable of powering a 2-V load at up to 6 mW. The auxiliary RF harvester uses a fully-integrated charge pump to impedance-match to a rectenna with greater than 94% matching. The parasitic models developed for the RF harvester show errors less than 1.4% in the measured system.