RF Energy Harvesting System Research Articles

Analysis and Design Methodology of RF Energy Harvesting Rectifier Circuit for Ultra-Low Power Applications.

This paper reviews and analyses the design of popular radio frequency energy harvesting systems and proposes a method to qualitatively and quantitatively analyze their circuit architectures using new square-wave approximation method. This approach helps in simplifying design analysis. Using this analysis, we can establish no load output voltage characteristics, upper limit on rectifier efficiency, and maximum power characteristics of a rectifier. This paper will help guide the design of RF energy harvesting rectifier circuits for radio frequency identification (RFIDs), the Internet of Things (IoTs), wearable, and implantable medical device applications. Different application scenarios are explained in the context of design challenges, and corresponding design considerations are discussed in order to evaluate their performance. The pros and cons of different rectifier topologies are also investigated. In addition to presenting the popular rectifier topologies, new measurement results of these energy harvester topologies, fabricated in 65nm, 130nm and 180nm CMOS technologies are also presented.

Design and simulation of a voltage mode controlled boost converter for low power RF energy harvesting system

Design and simulation of a voltage mode controlled boost converter for low power RF energy harvesting system

Design and simulation of a voltage mode controlled boost converter for low power RF energy harvesting system

Design and simulation of a voltage mode controlled boost converter for low power RF energy harvesting system

A Novel Dual-band Ambient RF Energy Harvesting System for Autonomous Wireless Sensor Node Application

This paper presents a novel dual-band ambient Wi-Fi energy harvesting system for an autonomous wireless sensor node (AWSN) which operates independently without other external power source. While conventional wireless sensor nodes employing batteries with limited lifespans, an AWSN is supplied by harvested energy and does not require frequent battery replacement. Due to that reason, research on the energy harvesting aspect of AWSNs has been carried out intensively in recent years. By optimizing the matching network, the proposed ambient Wi-Fi energy harvesting system achieves a relatively good efficiency in dual-band at 2.45 GHz and 5.8 GHz. The efficiency reaches a peak at 47.45 % and 42 % at 2.45 GHz and 5.8 GHz, respectively. The proposed idea is numerically and experimentally demonstrated with the Wi-Fi source in building.

CP Antenna with 2 × 4 Hybrid Coupler for Wireless Sensing and Hybrid RF Solar Energy Harvesting.

The main challenge faced by RF energy harvesting systems is to supply relatively small electrical power to wireless sensor devices using microwaves. The solution is to implement a new device in a circularly polarized rectenna with circular polarization sensitivity integrated with a thin-film solar cell. Its dual-feed antennas are connected to a 2 × 4 asymmetric hybrid coupler and a multi-stage voltage doubler rectifier circuit. This configuration has a 2 × 4 asymmetric hybrid coupler used to produce 4 outputs with a 90-degree waveform phase difference. The two ports can independently be connected to the wireless sensor circuit: radiofrequency harvesting of hybrid energy solar and information equipment can be carried out with these two antennas. The Dual-Feed circular patch antenna has a two-port bandwidth of 137 MHz below −15 dB and an axial ratio of less than 3 dB, with a center frequency of 2.4 GHz with directional radiation and a high gain of 8.23 dB. It can be sensitive to arbitrary polarization of the input voltage multiplier waveform to overcome uncertainty in empirical communication environments. A parallel structure is arranged with a thin film solar cell integration from the transmitter with an output voltage of 1.3297 V with a compact composition and RF energy. The importance of adopting a wireless sensor strategy with circular polarization sensitivity and integrated RF solar energy harvesting rather than a single source method makes this research a significant novelty by optimizing the analysis of multiple wireless sensor signal access.

Remote‐controlled reconfigurable hexa‐band antenna for radio frequency energy harvesting systems

SummaryIn this paper, a compact (15.5 × 32 mm2) reconfigurable microstrip antenna with hexa‐band operation for radio frequency (RF) energy harvesting applications is presented. Three PIN diodes (D3, D2, and D1) for switching action and internet of things (IoT) controlled unit for controlling the resonating frequency of the proposed antenna are used. The antenna resonates at 2.1 and 3.4 GHz (010 state), 3.3 GHz (100 state), 3.2 GHz (101 state), 3 GHz (110 state), and 2.8 GHz (111 state). The proposed antenna exhibits −10 dB simulated and measured impedance bandwidth of 150, 400, 480, 570, 370, and 400 MHz and 120, 410, 400, 470, 320, and 356 MHz in states‐010, 100, 101, 110, and 111, respectively. A maximum peak gain of 3.3 dBi and maximum bandwidth of 570 MHz at 3.2 GHz (101 state) is observed. The proposed antenna is further tested for harvested power, and maximum harvested voltage of 3.9 V, maximum harvested power of 3.013 mW, and 55.07% power conversion efficiency at 20‐dBm power source are recorded. The simulated results have been validated with experimental results.

A Self Threshold Voltage Compensated Rectifier for RF Energy Harvesting using 45nm CMOS Technology

A high frequency rectifier is the core of a RF energy harvesting system. It should offer a very good efficiency at low input power levels and to obtain that compensation of threshold voltage is a very important aspect. A threshold compensation scheme for MOSFETS for RF rectifier applicable in RF energy harvesting system is presented in this paper. The switching of the MOSFET is improved with overall enhancement of output rise time of the system. The design emphasis is to have a simplified circuit without the requirement of any external source so as to achieve self-sustainability in the true sense. The rectifier circuit is derived from the basic Dickson charge pump model and is evaluated using 45nm CMOS process. The design has utilized Metal Oxide Semiconductor Field Effect Transistor instead of basic diodes which ensures low power along with fabrication feasibility. The maximum measured PCE of the design is obtained to be 33% at 4dBm input power level at 500Mhz frequency with 1 Kilo Ohm load resistance. The output transient response rise time has been measured to be 85ns at 500MHz and 50.10ns at 1Ghz.

High-Efficiency Triple-Band RF-to-DC Rectifier Primary Design for RF Energy-Harvesting Systems

Radio Frequency (RF) energy harvesting has been emerged as a potentially reliable method to replace the costly and difficult to maintain source of low-power wireless sensor networks. A plethora of dual-band rectifier designs has been proposed in the literature operating in various frequency bands. In this paper, a triple-band RF-to-DC rectifier that operates in the frequency bands of LoRaWAN, GSM-900, and WiFi 2.4 GHz is presented. The system is composed of an impedance-matching circuit, an RF-to-DC rectifier, that converts the ambient RF energy into DC voltage able to feed low-power devices, and an output load. The proposed system resonates at three different frequencies of 866 MHz, 948 MHz and 2423 MHz, which fall within the aforementioned frequency bands of interest. The feasible solution of the proposed system was based on a dual-band rectifier operating in the frequency bands of LoRaWAN and GSM-900. A series of shunt stubs was utilized in the initial design to form the feasible solution of the proposed system. The proposed triple-band rectifier was optimized using a powerful optimization algorithm, i.e., the genetic algorithm. The overall system exhibited improved characteristics compared to the initial design in terms of its resonance. Numerical results demonstrated that the overall system exhibited an efficiency of 81% with 3.23 V of the output voltage, for an input power of 0 dBm and a load of 13 kOhm.

Differential multiresonator stacked microstrip antenna for wireless energy harvesting

In this communication, various planar multiple resonators stacked microstrip antennas with differential inputs/outputs for wireless energy harvesting are presented. The antennas are designed for GSM 900 band using thick substrate on low-dielectric constant. The developed antennas are fabricated on two different substrates to study and compare the efficiency of complete differential RF energy harvesting system. Gain of 9.03, 10.5, 10.62, and 12.05 is achieved for a broad bandwidth of 12, 17.5, 17.9, and 20.2% respectively for various antenna prototypes. Measured results show a peak efficiency of 70.85, 72.49, 75.68, and 86.33% for a load of 2, 1.2, 0.98, and 0.52 kΩ respectively. Finally, wireless power transmission is estimated using link budget analysis.

A single-branch impedance compression network (icn) optimized by particle swarm optimization algorithm for rf energy harvesting system

Most previous works regarding the impedance compression network ICNs reported in the literature consist of dual branches to carry out the compression functionalities. Although this type of circuits are efficient, they are complex and have large sizes. This work proposes a complex impedance compression network with only a single branch for wireless power transfer (WPT) circuits, operating at 2.4GHz under a wide input power range and a variable load. The design size is about 4x4.2mm2 which thereby, produces a simple, and small design. The simulation results demonstrate that the improvement in efficiency is by 10%, as compared to a design without ICN. The improvement can increased by utilizing the particle swarm optimization PSO algorithm where the best dimensions of the ICN components will be selected relying on the suitable fitness function in the PSO algorithm to the given desired goals. The impedance matching is also enhanced in which it stands behind the conversion efficiency increment. The circuit size is very slightly increased and it becomes 4.2x4.3mm2. The final design has a conversion efficiency about 76%, with more than 15% improvement to a design with only a matching circuit or without using the automation techniques. Eventually, results show that the enhancement is obtained not only the designated input power but also along a range of the input power.

A Survey of RF Energy Harvesting Circuits

The aim of this work is, on one hand, to review the state of the art of the architectures and diodes used in radio-frequency energy harvesting systems, the idea here is to review the most recent works, as well as their characteristics, which include frequency, type of diode used, topology, maximum efficiency and corresponding power, and on the other hand to carry out simulations to determine the most appropriate case for any further work in the field. After having determined the most common topologies, we used the main known radio-frequency diodes to characterize them in a first step, clearly a process of comparing the results of the simulations of the different topologies is done by initially considering an identical frequency. and afterward determine the effect of frequency band on their conversion efficiency.

A Long-Range and Self-Powered Intelligent Food Monitoring System Based on Far-Field Energy Harvesting and Pressure Measurement

Introduction In recent decades, food safety is becoming a top concern in the world because it is directly related to human health. According to World Health Organization statistics, about 550 million people are poisoned each year because of unsafe food consumption. One of the leading causes of foodborne illnesses is the consumption of rotten and expired foods. Therefore, the development of a food monitoring system is essential. Indeed, many studies have focused on developing battery-free food monitoring systems based on radio frequency energy harvesting (RFEH) technology due to its benefits such as durability, low cost, and safety for stored food [1]-[2]. The major disadvantage of these studies is that they estimated food quality using gas sensors, which require large energy consumption (typically over 10mW). Moreover, the gas sensors need a long time to heat up to obtain accurate sensor data. These drawbacks reduce the feasibility of implementing these systems in practice.This paper aims to develop a self-powered battery-free food monitoring system based on far-field RFEH technique and pressure measurement, which can overcome the problems with the conventional methods. Methods and Experiments The overview architecture of our proposed system is depicted in Fig.1. The self-powering capability of the sensor tag is provided by converting the radio wave transmitted from an RF generator into electrical signals. The antenna is the first component and plays a vital role in an energy harvesting system. To improve the received power and enhance the distance of power transfer, we have developed a printed Yagi-Uda Three element (driver, director, and reflector) because of its simplicity in design, high gain, compact size, and low cost [3]. The operating frequency of the antenna is chosen at the unlicensed Industrial Scientific Medical (ISM) band of 915MHz. Besides, in this study, we focus on monitoring the gradual increase of the air pressure inside the food container due to gas emission during food degradation. The air pressure sensor has ultra-low energy consumption and high precision, suitable for the limited energy condition of far-field RFEH system. Finally, we conduct a set of experiments with different sorts of food, such as pork, fish, and chicken, to demonstrate the feasibility of the proposed method. Results and Conclusions As a result, the designed Yagi antenna has a high gain of 6.54dBi in the direction of the maximum radiation, better than the isotropic antenna in some conventional systems that usually achieve about 1.7 dBi [1]. The reflection coefficient of the Yagi-Uda antenna achieved -26.8dB and voltage standing wave ratio (VSWR) better than 1.3 in approximately 60 band (890-950 MHz). At a distance of 6 meters, the harvested RF power reach -10.9dBm , and the rectifying voltage was obtained at 380mV , which is high enough for the tag to launch its functions. The sensor unit is designed with ultra-low power components and consumes only 300μW on average. The air pressure, temperature, and humidity data obtained from the sensor tag are used to evaluate and estimate the food quality, demonstrating the proposed method's effectiveness.

Metamaterial Impedance Matching Network for Ambient RF-Energy Harvesting Operating at 2.4 GHz and 5 GHz

This paper points out the viability of the utilization of metamaterial transmission lines as a multifrequency impedance matching network, improving RF-Energy Harvesting systems operating around 2.4 GHz and 5 GHz. Metamaterial transmission lines introduce additional degrees of freedom in the transmission line design, providing the possibility to match the impedance in multiple bands. The impedance matching structure has been designed and optimized using ADS simulator to match the input impedance of a four-diode-bridge rectifier connected to an energy management system. The proposed Metamaterial Impedance Matching Network (MIMN) has been fabricated using standard PCB technologies and tested in a full operative ambient RF-Energy Harvesting System obtaining a DC output voltage of 1.8 V in a 6.8 mF supercapacitor.

Power Conversion Using Analytical Model of Cockcroft–Walton Voltage Multiplier Rectenna

A voltage multiplier rectenna is a combination of a voltage multiplier rectifier and an antenna used for the conversion of AC to DC. It is an essential part of the system of RF energy harvesting. Conventional rectennas are characterized by low conversion efficiency. This study presents an analytical novel mode designed for RF energy harvesting systems to study the voltage and current output of rectifier stages for efficiency optimization. The design contains a voltage multiplier rectification circuit with seven stages. The Schottky diode HSMS 285-C was selected for the circuit modeling voltage multiplier circuit. Advanced Design System (ADS) simulation was used to validate the equations of the theoretical model solved with MATLAB code. The fabricated system was tested for an input power range of 10 μW to 100 mW; the maximum output power is 0.2577 mW with maximum efficiency of 29.85%.

A dual-input extended-dynamic-PCE rectifier for dedicated far-field RF energy harvesting systems

This paper presents a dual-input extended-dynamic-range, high-PCE rectifier for dedicated far-field RF energy harvesting systems. Two identical input RF energy supply source are applied into two individual rectifier. The rectifier with the highest PCE is selected to deliver dc power to a single-load element. A logic control circuit senses Pin from the rectified dc voltage and toggles between the rectifiers by generating two control voltage to attain high-PCE across Pin. Simulated in a 65nm CMOS process, the proposed system achieves an extended DR of 26 dB for an output load, RL = 100 kΩ. Furthermore, a peak PCE of 54.85% and 47.87% was achieved for RL = 100 kΩ and RL = 150 kΩ, respectively. The sensitivity for an output voltage of 1 V with RL = 100 kΩ is -20.6 dBm.

이중 편파 RF 에너지 하베스팅 시스템을 위한 최적 정류 회로 설계

이중 편파 RF 에너지 하베스팅 시스템을 위한 최적 정류 회로 설계

Digital Evaluation Algorithm for Upper Limb Motor Function Rehabilitation Based on Micro Sensor

The electroencephalogram (EEG) of the cerebral cortex reflects the upper limb motion control information of the human body. The electro myographic signal (EMG) of the body muscle tissue reflects the response of the upper limb muscle to the brain control. The intersection of two physiological electrical signals has become a new hot field in artificial intelligence, medical rehabilitation and neuroscience. Firstly, starting with the analysis of the power consumption characteristics of the micro-sensor system, by studying the working principle and design scheme of the energy self-capture technology, various energy supply methods of the combined vibration energy harvesting system, the thermoelectric energy harvesting system and the RF energy harvesting system are proposed. Combined upper limb exercise rehabilitation energy is self-capture program. Secondly, the upper limb motor EEG and EMG signal acquisition experiments were designed to preprocess the acquired signals. Based on the wavelet threshold denoising method, an improved threshold algorithm is proposed to remove the noise in the EEG signal and improve the signal-to-noise ratio of the EEG signal. On the basis of the wavelet analysis method, the stratified threshold denoising method is applied to the collected EMG signals for denoising processing and digital evaluation of upper limb motor function rehabilitation. Finally, a digital evaluation method for upper limb motor function rehabilitation combined with wavelet low-frequency coefficients and significant information is proposed. The algorithm combines wavelet transform, motion estimation, and significant information to design a video quality evaluation algorithm. It can be seen from the experimental results that the performance of this algorithm is superior and maintains high consistency with the human motion system.

A High-Efficiency Dual-Antenna RF Energy Harvesting System Using Full-Energy Extraction With Improved Input Power Response

This paper presents a dual-antenna energy harvesting (EH) system using full-energy extraction (FEE) to reduce the buffer capacitor requirement and improve the input power response speed. Instead of using large buffer capacitors (in the order of μF) at the rectifier output, the proposed FEE technique can efficiently harvest the incoming 915MHz radio-frequency (RF) energy using only a 1-nF capacitor per channel, while reducing the operating frequency of the subsequent DC-DC converter for power loss minimization. The two most popular RF rectifiers are investigated to relax the energy extraction degradation due to impedance mismatch. The boost DC-DC converter combines the harvested energy from the dual-inputs through the FEE controller. Fabricated in standard 0.18-μm CMOS and wire-bonded on an FR4 PCB, the dual-antenna EH system with the DC-DC converter operating typically at 6.25kHz demonstrates a measured peak system efficiency of 75.2% at an output power of 22.6 μW using only two 1-nF buffer capacitors at 1-μF load. With a significant buffer size reduction than prior art at similar efficiency/power level, a short startup time of ~45ms is achieved when the output rises from 0 to 1 V at 15.5 μW total rectifier output power, corresponding to 90% startup time reduction over the conventional approach.

Design and simulation of medium wave-based RF energy harvesting system with feedforward controlled DC to DC boost converter

Design and simulation of medium wave-based RF energy harvesting system with feedforward controlled DC to DC boost converter

Impact of Varying Radio Power Density on Wireless Communications of RF Energy Harvesting Systems

Through field experiments, we observed a varying instantaneous charging capacity of the energy buffer with respect to the dynamic intensity of the incident RF signal in the RF energy harvesting system (RF-EHS). The dependency of charging capacity on the incident power of RF signal challenges existing RF energy harvesting models that assume constant charging capacity. In order to accurately describe the energy harvesting process in the real system, we propose a new energy clamp model. The new model reveals that RF intensity higher than the sensitivity of the harvester circuit cannot always guarantee successful energy reception, especially when the energy level of energy buffer is high while the intensity of the incident power is relatively weak. In order to improve the efficiencies of energy harvest and energy utilization in an RF-EHS, we develop new offline (i.e., non-causal) optimal and online (i.e., causal) suboptimal data transmission strategies based on the energy clamp model. Simulation results show that the new strategy can considerably improve the throughput after taking into account the varying instantaneous charging capacity caused by the dynamic RF power density in the air.