A 915 MHz Closed-Loop Self-Regulated RF Energy Harvesting System for Batteryless Devices

Abstract

Batteryless devices are essential for hard-to-reach applications such as implantable biomedical devices.Powering such devices is a difficult task, and energy harvesting from the environment is mandatory. Among the power sources available in urban areas, RF signals stand out. However, the RF power at the receiving antenna is not constant, and energy-harvesting circuits should provide a stable DC output voltage. In this paper, we present an RF energy harvestingbased power management system that provides a stable 0.4-V DC supply voltage to power low-voltage systems. A closed-loop impedance matching tuning system is used to automatically regulate the system DC output voltage by tuning the input impedance matching network. The proposed circuit is implemented at schematic level in a 65-nm standard CMOS process.The entire system power efficiency (PCE) is 48.28% at the input power level of -14.92 dBm. The proposed solution is demonstrated for powering low-voltage devices with a regulated output voltage of 0.4 V and 16 uW resistive load.