The Advancement of Radio Frequency Energy Harvesters (RFEHs) as a Revolutionary Approach for Solving Energy Crisis in Wireless Communication Devices: A Review

Abstract

In this paper, the evolution and milestones of RFEH and related breakthroughs over the years are reviewed and presented. The review begins with an overview of the surging energy crisis due to the increasing demand for wireless communication devices. Furthermore, the RFEH mechanism that discusses the frequency bands utilized, the near field, and the far field propagation are also presented. Various rectification techniques in CMOS RFEH, from the fundamental rectification method to cross-coupleddifferential-drive (CCDD), are also examined and discussed. The performance is gauged through harvested output DC voltage and the power conversion efficiency (PCE) as well as the RF input power sensitivity. An assessment on the non-CMOS RFEH that includes the Schottky diode and Rectenna is also concisely described to analyze their contribution to RFEH's performances enhancement. Finally, a special highlight of the 5G RFEH in mmWave is provided in the presentation of this work as an ongoing future solution to reduce the electronic circuit's battery dependency. The pros and cons of all the presented RFEHs are summarized and discussed as well. Continuous research and development activities are extensively being executed in developing a system that could ultimately solve the world's energy crisis and RFEH seems to be a revolutionary approach.

High-Performance Multiband Ambient RF Energy Harvesting Front-End System for Sustainable IoT Applications—A Review

“…where n is the number of cascaded stages. Dickson-type rectifier produces a high voltage at the cost of poor sensitivity and lowers PCE [8], [9], [77]. As observed from (10), the output voltage of the Dickson-type rectifier suffers from the inevitable drop of V TH .…”

“…CCDD-type rectifier achieves high peak PCE but narrow PDR [8], [9], [77]. This transpires as the CCDD-type rectifier suffers from unwanted reverse leakage current at high RF input [17].…”

Link Budget Analysis for Backscatter-Based Passive IoT

“…Reducing the rectifier's energy consumption to improve the RF-DC conversion [91], [92]. With RF EH design based on CMOS, we can achieve a high RF EH activation threshold (more than −20 dBm) and self-startup power consumption as low as hundreds of nA.…”

“…However, this setup requires a long design, production time, and expensive chip manufacturing costs [84]. A good summary of the RF EH circuit design based on CMOS and Schottky diodes and their performance is provided in [91], [99], [100].…”

“…Ambient RF signals such as TV, FM, UMTS, GSM, Wi-Fi, Long Term Evolution (LTE), and 5G-NR, have the lowest power density compared to other ambient sources like solar, thermal, and vibrational [116]. Hence, ambient RF sources are variant along with their power level [91], [100]. RF energy harvester thus should accommodate various input power levels and maintain the optimal efficiency [117].…”