An RF energy harvester with 35.7% PCE at PIN of −15 dBm

A 900-MHz system is designed to harvest ambient RF energy and generate 2-V output voltage. An efficient power path structure with adaptive control is proposed to maintain close-to-optimal power conversion efficiency. The control circuit consumes low power by adopting a novel open-loop asynchronous control scheme and duty-cycled operation. A startup circuit is also presented. Measurement results show minimum P_IN for startup of -17 dBm, end-to-end PCE of 35.7% at P_IN of -15 dBm, and quiescent current of 1.56 μA at VOUT of 2 V.