A Versatile RF Energy Harvester for IoT Sensors in 5G Network With Extended Input Power Range

Abstract

The widespread adoption of fifth-generation (5G) wireless technology in Internet of Things (IoT) networks introduces a battery replacement challenge for countless IoT sensors. To address this issue, researchers are exploring energy harvesting techniques that involve extracting energy from radio frequency (RF) signals. The dense deployment of antennas in 5G networks, compared to prior technologies, ensures that an RF energy source is available in close proximity to IoT sensors which can be utilized as reliable power sources for these sensors. This study focuses on the design of an efficient energy harvester for low-power IoT sensors. Specifically, the investigation centers around a scenario where dedicated directional transmitters emit continuous waves to power up IoT sensors. An optimized high-efficiency Dickson rectifier circuit is designed to convert the RF signal to DC at a high-frequency band over a wide dynamic range. The Dickson rectifier is superior for low-power, high-frequency scenarios due to its voltage multiplication and reduced losses. To minimize the effect of parasitic capacitance associated with conventional capacitors, interdigital capacitors (IDC) are designed on an FR-4 substrate with a thickness of 1.57 mm. An impedance-matching circuit utilized as a passive voltage amplifier was also employed to enhance the RF-to-DC conversion efficiency. A prototype was built and tested at the 5.2 GHz frequency band. The measurement results demonstrate the peak efficiency of the proposed energy harvesting circuit which was determined to be 73.46% when subjected to an input power of -5 dBm at 500~Ω load and 49.12% with -10 dBm input at 1 MΩ. The proposed energy harvesting solution can operate efficiently across a broad dynamic range, outperforming the solutions reported in the literature.