An RF-EH Employing Controlled-Impedance Matching for Ultra-Low Voltage Batteryless Devices

Harvesting energy from the existing RF signals present in the environment is a key strategy to power ultra-low voltage (ULV) devices. Such harvesters should present high power conversion efficiency and it is directly affected by the antenna-harvester impedance matching. This paper introduces an RF-EH system with an adapted and digitally-controlled impedance matching approach for batteryless devices. The proposed circuit is designed on a 180-nm CMOS process and is capable of generating a stable supply voltage of 0.4- V from a frequency of 915 MHz while achieving a sensitivity of -19.l6-dBm and 66% power efficiency.