A Stage–Stage Dead-Band Compensated Multiband RF Energy Harvester for Sensor Nodes

This article presents a dead-band compensated multiband stacked electromagnetic energy harvester for powering sensor nodes. It is adaptive for typical ambient radio frequency (RF) power levels found within the environment. A stage–stage feedforward technique is adopted in the proposed harvester to enhance the output voltage, in turn, harvested power and sensitivity. Moreover, a compensation circuit is included in the design for bypassing the inactive bands to avoid unexcited band rectifier diodes. A prototype is designed to cover four frequency bands GSM (900 and 1800 MHz), 4G-LTE (2.3 GHz), and Wi-Fi (2.4 GHz) and further integrated with a TI BQ25570 power converter. The analytical, simulated, and measured results show the increment in the output voltage with the frequency bands. The measured efficiency of the RF-to-dc converter is 44.2% at −20-dBm input power and 89% at 0 dBm. The efficiency is improved by 13% on average under dead-band compensation. With the multiband stacking, the harvester achieves a start-up voltage of 320 mV at −24 dBm and is found to be efficient to drive a temperature sensor STLM20 at −12-dBm input power.