Radio Frequency Rectifier Research Articles

Evolutionary algorithm for minimizing the temperature influence of low power RF Energy Harvesting circuits

The aim of this work is to analyze and optimize the design of low-power Radio Frequency (RF) Energy Harvesting rectifiers by using an Evolutionary Algorithm. Although, generally neglected in the literature, the RF rectifier operation strongly depends on the operation temperature. When it varies, the input impedance can change significantly, affecting the circuit matching and its power conversion efficiency. In this work, an evolutionary algorithm is used to identify which parameters of an RF diode are responsible for the performance degradation as a function of temperature and to optimize the rectifier circuit in order to reduce the temperature influence. This work demonstrates that the saturation current, the zero-bias junction capacitance, the load and the series resistance have an important impact in designing an optimized circuit. Results indicate that the applied algorithm can be used aiming the project of a circuit more robust to temperature variations. The obtained results have also been compared to experimental ones, corroborating the analysis.

Advancing IoT wireless sensor nodes with a low profile multiband RF rectifier based on multi-stub J-Inverter network

In this paper, a unique RF rectifier design is introduced, employing a multi-stub J−Inverter impedance matching network (IMN). The structure of the IMN comprises a series of three sections with multiple stub tuning elements interconnected via a meandered line (MDL) to form multi-frequency susceptance blocks. The rectifier has been developed to work at frequency bands: 1.84, 2.10, and 2.45 GHz. These frequencies align with the designated bands for GSM/1800, UMTS/2100, and Wi-Fi, respectively. By implementing a complete ground architecture, the rectifier utilizes a minimal space of 0.57λg×0.3λg on the RT/Duroid 5880 PCB board. The experiment’s outcomes show the proposed RF rectifier’s effectiveness in converting radio frequency (RF) signals into direct current (DC) power (RF-to-DC). The results indicate PCE values of 32.70%, 27.60%, and 24.50%, corresponding to input powers of -20 dBm at the targeted operational frequencies. Additionally, the rectifier design proposed within this study achieves its peak RF-to-DC PCE of 75.30% when energized by an input power of 3 dBm. Moreover, notable stability is demonstrated by the rectifier, sustaining an RF-to-DC PCE surpassing 50% throughout the frequency range spanning 1.7 to 2.4 GHz. This robust performance remains consistent even at lower input power levels, such as -10 dBm Furthermore, the rectifier can produce a direct current (DC) voltage output ((VDC)), measured at 0.411 V in an ambient context. The integration of the rectifier with the power management module (PMM), facilitated through the utilization of the bq25504-674 evaluation module (EVM), successfully established a connection within the PMM system. This integration yielded a (VDC) of 1.270 V. Hence, through proficient management of the proposed RF rectifier, it becomes feasible to utilize ambient RF signals to energize a range of low-energy devices effectively.

Additively Manufactured and Liquid Metal-Sprayed Rectenna for Energy-Harvesting Application

This research demonstrates the additively manufactured dual-band radio-frequency (RF) energy harvester for green Internet of Things (IoT) applications. The proposed energy-harvesting system consists of a dual-band circular monopole antenna (CMA) array, an impedance transformer, and a RF rectifier. The CMA array is printed on the circular substrate having a radius of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.007\lambda _{g}^{2}$ </tex-math></inline-formula> to achieve a compact size. The single-stage Villard rectifier converts the RF signal to dc voltage and the impedance transformer matches the impedance between the antenna and the rectifier. The proposed rectenna is 3-D printed on a biodegradable polylactic acid (PLA) substrate using fused deposition modeling (FDM) of 3-D printing. The experimental verification is carried out in RF ambient environment using a horn antenna and RF signal generator. The fabricated configuration offers conversion efficiencies of 72.2% and 51.21% at 2.4 and 5.2 GHz, respectively. The simulation and test results of the proposed configurations are in good agreement. The designed energy harvester would be a suitable source for low-power wireless sensor network-based green IoT applications.

RF enerji hasatlama için 915 MHz taşıyıcı frekansında mikroşerit anten tasarımı ve uygulaması

Nowadays, Radio Frequency (RF) energy harvesting systems are called an alternative energy source and target to use the electromagnetic energy available in the environment. One of the purposes of these energy harvesting systems is to extend battery life by being used with communication systems with low power consumption. RF energy harvesting system consists of antenna, impedance matching, RF rectifier circuit, DC filter circuit and load. In this study, a microstrip antenna model with a carrier frequency of 915 MHz and a bandwidth of 200 MHz was designed with the help of HFSS program that solves electromagnetic structures by finite element method. The proposed antenna size of 79x100x1.6 mm3 has been optimized using parametric analysis. Later, designed antenna is fabricated on a low profile FR4 substrate. In the last step, the measurements of the antenna were taken by the vector network analyzer device and the characteristics such as return loss, VSWR and radiation pattern were evaluated. The designed antenna gain is calculated as 2.38 dB. In addition, it has been observed that the measurement and simulation results of the antenna are compatible. Finally, considering the results of this study, it has been determined that the proposed antenna is suitable for RF energy harvesting systems operating at 915 MHz carrier frequency.

Energized IOT Sensor through RF Harvesting Energy

Wireless Power Collecting (WPC) present the future in powering and energizing intelligent Internet of Things (IoT) electronics devices. This chapter studies and utilizes a circuit to powering wirelessly IoT devices. The WPC offer a best technique to help researchers and engineers of modern societies to build cell blocks. The concept is to energy any IoT devices and sensors wirelessly from Radio Frequency (RF) power strength in the same areas that may be hard to achieve or potentially hazardous. We implemented the RF harvesting technology with IoT devices to increase the efficiency of sensors. The idea of this system is to power up and self-energize any IoT sensors wirelessly. This work studies two different topologies of a rectangular patch antenna and different RF harvesting circuit voltage multiplier configurations using a microwave power station as the input RF source. This work aims to utilize the wireless power transmission technique in the smart house solution. The proposed prototype gets all technical parameters to generate enough electricity to power up the bulbs 5 W wirelessly at a gap distance around a five meters. Finally, we test the RF rectifier circuit coupled with a twin patch antenna that can self-energize the bulb, eventually devices work without batteries.

RF Rectifiers With Wide Incident Angle of Incoming Waves Based on Rat-Race Couplers

This article presents a radio frequency (RF) rectifier with a wide incident angle of incoming waves, based on a rat-race coupler (RRC). Two identical sub-rectifiers replace the two load circuits of the conventional RRC. When compared with the previous Wilkinson power combiner (WPC)-based rectifier, the proposed topology advances with a smaller variation in power conversion efficiency (PCE) over the incident angle. In addition, it simplifies the matching network (MN) design and enables a lower input return loss due to the fully symmetric circuitry between 0&#x00B0; and 180&#x00B0;. Furthermore, it allows a higher design flexibility on the rectifier topology. For validation, we designed and fabricated two wide-angle rectifiers, one working at single band (2.45 GHz) and the other at dual band (0.9 and 2.4 GHz). The single-band rectifier achieved a 67.3&#x0025; peak PCE and 7.9&#x0025; efficiency variation within the 0&#x00B0;&#x2013;360&#x00B0; incident angle range. For the dual-band rectifier, the peak PCE is 78.4&#x0025; and 70.2&#x0025;, while the variation is 4&#x0025; and 8.8&#x0025;, for 0.9 and 2.4 GHz, respectively. The PCE variation is the smallest among previous works.

14GHz Schottky Diodes Using a p-Doped Organic Polymer.

The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes hinder their deployment in emerging radio frequency (RF) electronics. Here, these limitations are overcome by combining self-aligned asymmetric nanogap electrodes (≈25nm) produced by adhesion lithography, with a high mobility organic semiconductor, and RF Schottky diodes able to operate in the 5G frequency spectrum are demonstrated. C16 IDT-BT is used, as the high hole mobility polymer, and the impact of p-doping on the diode performance is studied. Pristine C16 IDT-BT-based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (fC ) of >100and 6GHz, respectively. This extraordinary performance is attributed to the planar nature of the nanogap channel and the diode's small junction capacitance (<2pF). Doping of C16 IDT-BT with the molecular p-dopant C60 F48 improves the diode's performance further by reducing the series resistance resulting to intrinsic and extrinsic fC of >100and ≈14GHz respectively, while the DC output voltage of an RF rectifier circuit increases by a tenfold. Ourwork highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large-area RF electronics of the future.

Compact dual-band RF rectifier for wireless energy harvesting using CRLH technique

&lt;p&gt;In this paper, a new dual-band radio frequency (RF) rectifier was designed. The proposed design is a low-profile structure with dimensions of &lt;br /&gt; 5×5.5 mm&lt;sup&gt;2&lt;/sup&gt; owing to the use of lumped elements rather than the conventional transmission lines which occupy large footprints. This property can be potentially exploited to use the proposed rectifier in high dense rectenna arrays to generate high output direct current (DC) voltages. Furthermore, the proposed design adopts the composite right/left-handed composite right left-handed (CRLH) technique to realize the dual-band structure at frequencies of 1.8 and 2.4 GHz. Afterward, the matching circuit was optimized to make sure that it offers good matching. The frequency response shows good matching at both bands which are about -22 and -25 dB respectively. Eventually, the simulated circuit has a conversion efficiency of 52% and output voltages of 0.5 V at -5 dBm for the two bands.&lt;/p&gt;

Broadband High-Efficiency RF Rectifier With a Cross-Shaped Match Stub of Two One-Eighth-Wavelength Transmission Lines

This letter presents a broadband rectifier that can be applied to harvest ambient radio frequency (RF) energy. The matching network consists of three-stage transmission lines. A cross-shaped match stub of two one-eighth-wavelength transmission lines is proposed to realize efficient and broadband impedance compression. The proposed circuit has been optimized and manufactured, and the measured results show that the rectifier can achieve high RF-to-dc conversion efficiency and broadband characteristics. The simulation and measured results were basically consistent. When the input power is 8 dBm and the terminal load is 1.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> , a bandwidth of 81% (1–2.35 GHz) with an efficiency above 50% and a bandwidth 69% (1–2.05 GHz) with an efficiency above 60% are achieved. The highest conversion efficiency of the test circuit is up to 73.2% at an input power of 8 dBm. Moreover, when the input power changes from 1 to 11 dBm, the efficiency of the rectifier circuit is always above 50%.

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.

Harmonic Suppression RF Rectifier Design With a New Experimental Analysis Based on Voltage and Efficiency Level Curves

This letter describes the design, simulation, and measurement process of a series radio frequency (RF) rectifier at the 2.4 GHz ISM band, composed of a distributed filter with radial stub elements. The proposal is to reduce the first- and second-order harmonic components that are generated by the diode nonlinearities at the rectifier output. The efficiency and output voltage are presented according to load values ranging from 1 to 10 kQ. These figures of merits are obtained with a new methodology, using an automatized measuring setup, which describes in detail the behavior and nuances of the circuit according to the frequency and input power through experimental level curves. The proposed RF rectifier prototype reaches over 20% efficiency for input power levels over -20 dBm for the lower load values, showing a satisfactory performance in comparison with other proposals for low-power applications.

Design of Compact Dual-Band RF Rectifiers for Wireless Power Transfer and Energy Harvesting

In this paper, we propose a compact dual-band impedance matching network (DBIMN) for radio frequency (RF) rectifiers. The DBIMN is achieved with a single-stage T-type network, with only three segments of the transmission line. We investigate the closed-form design equations, as a design guideline of the DBIMN. In addition, we propose the design methodology of the rectifier using the DBIMN. For validation, we design two dual-band rectifiers (0.915 and 2.45 GHz), for different input power levels. The rectifier with high input power level, is designed for a wireless power transmission (WPT) system. With a 12 dBm input power, the measured power conversion efficiencies (PCEs) are 81.7 and 73.1% at the working frequencies. The PCEs becomes 69.2 and 64.1% (at −1 dBm input power) for the low-power input rectifier that can be used in an RF energy harvesting (RF-EH) system. The simulated and measured results match each other well. Compared with previous designs, the proposed designs have advantages in compactness and high efficiency.

A 30mV input battery-less power management system

This paper presents a fully-integrated on chip battery-less power management system through energy harvesting circuit developed in a 130nm CMOS process. A 30mV input voltage from a TEG is able to be boosted by the proposed Complementary Metal-Oxide-Semiconductor (CMOS) voltage booster and a dynamic closed loop power management to a regulated 1.2V. Waste body heat is harvested through Thermoelectric energy harvesting to power up low power devices such as Wireless Body Area Network. A significant finding where 1 Degree Celsius thermal difference produces a minimum 30mV is able to be boosted to 1.2V. Discontinuous Conduction Mode (DCM) digital control oscillator is the key component for the gate control of the proposed voltage booster. Radio Frequency (RF) rectifier is utilized to act as a start-up mechanism for voltage booster and power up the low voltage closed loop power management circuit. The digitally control oscillator and comparator are able to operate at low voltage 600mV which are powered up by a RF rectifier, and thus to kick-start the voltage booster.

A survey on low power RF rectifiers efficiency for low cost energy harvesting applications

In this paper the analysis, simulation and prototyping of radio frequency rectifier topologies for ambient energy harvesting applications are evaluated, highlighting the effects of input power levels below −10 dBm. The equivalent diode impedance model is taken into consideration for better interpreting its effects when attached to each rectifier topology. Furthermore, the output capacitance modeling and its effects over the rectifier efficiency are discussed for different capacitance types, including a radial stub. A prototype of the most prominent topology was built on a low cost FR-4 substrate for RF harvesting in the range of −10 to −20 dBm, resulting in an approximate efficiency between 40% and 25%, respectively.

Self-switching diodes as RF rectifiers: evaluation methods and current progress

In the advancement of the Internet of Things (IoT) applications, widespread uses and applications of devices require higher frequency connectivity to be explored and exploited. Furthermore, the size, weight, power and cost demands for the IoT ecosystems also creates a new paradigm for the hardware where improved power efficiency and efficient wireless transmission needed to be investigated and made feasible. As such, functional microwave detectors to detect and rectify the signals transmitted in higher frequency regions are crucial. This paper reviewed the practicability of self switching diodes as Radio Frequency (RF) rectifiers. The existing methods used in the evaluation of the rectification performance and cut-off frequency are reviewed, and current achievements are then concluded. The works reviewed in this paper highlights the functionality of SSD as a RF rectifier with design simplicity, which may offer cheaper alternatives in current high frequency rectifying devices for application in low-power devices.

CMOS rectifier design for RFID chip with high sensitivity at low input power to be combined with an ultrasmall antenna

AbstractThis paper presents CMOS radio frequency (RF) rectifier circuit design for radio frequency identification (RFID) tag with integrated on‐chip antenna. The proposed design focuses on high sensitivity and high efficiency at low input power. The rectifier circuit was designed using Advanced Design System (ADS) software tool with the UMC130 process as a single‐ended rectifier structure in different topologies where sensitivity and efficiency enhancement techniques are applied. This work presents the performance of the proposed CMOS RF rectifier circuit in comparison with previously published works for 915 MHz and 5.8 GHz operating frequencies. For the 915 MHz band, the highest sensitivity of −19.8 dBm is provided by the adaptive threshold voltage compensation circuit with a power conversion efficiency of 9.843%. The 5.8 GHz band uses the adaptive threshold voltage compensation and dynamic bulk bias techniques providing the highest sensitivity of −16.8 dBm. Compared with other works in the literature, the proposed circuits offer greater sensitivity and can easily be matched with ultrasmall on‐chip antennas because of appropriate values of the input impedance.

Enhanced radio frequency rectifier with a power splitting/combining topology for wireless energy transfer and harvesting

Power splitting of the input radio frequency (RF) signal is used to improve the efficient power range of a RF rectifier. Direct current (dc) power at the output of every rectifying branch is then combined over a resistive load and thus resulting in a single dc output. The enhancement in efficient power range, over which the power conversion efficiency (PCE) remains ≥ 50%, is determined to be 2.8 dB. The article starts by a theoretical analysis that addresses the negative effects of the diode's breakdown voltage, formulates an equation that predicts the maximum output dc voltage at saturation, and introduces a method that can improve the PCE of a typical shunt-type diode rectifier at low power levels. As a result, a rectifying system is designed and tested as a proof of concept. The proposed circuit, with the enhanced power range, is designed to operate within the power span from -10 dBm up until 10 dBm. Such system is suitable for operation in RF wireless energy transfer and energy harvesting applications.

Single- and Dual-Band RF Rectifiers with Extended Input Power Range Using Automatic Impedance Transforming

This paper presents an automatic impedance transforming technique to extend the radio frequency rectifier input power range with high conversion efficiency. The rectifier employs two branches of subrectifier, each achieving impedance matching at high and low input power ranges. Then, the two branches are connected by a $\lambda/4 $ T-junction power divider. With such configuration, the input impedance of the two subrectifiers are transformed automatically, allowing the impedance matching over a wide input power range. In this way, the injected power can be optimally delivered to the subrectifiers, achieving a high efficiency over this wide input power range. This scheme manages to eliminate the power detetor for branch selection and can be applied to both single- and dual-band rectifiers with a reduced design difficulty. For validation, a single-band rectifier working at 915 MHz and a dual-band rectifier at 915/2450 MHz are implemented. Design analysis on the single- and dual-band rectifiers is carried out. The measurement results show that 68% maximum efficiency is achieved for the single-band (915 MHz) rectifier, and the input power range for the efficiency >70% of the peak efficiency is from −5 to 31 dBm. Besides, the dual-band rectifier shows 66% and 58% peak efficiencies at 915 and 2450 MHz, respectively. The input power range is from −6 to 33 dBm for the efficiency >70% of its peak value at 915 MHz, while from 10 to 32 dBm at 2450 MHz. These indicate that the input power range with high efficiency is extended.

An Ultra-Low-Power Integrated RF Energy Harvesting System in 65-nm CMOS Process

In recent years, radio frequency (RF) energy harvesting systems have gained significant interest as inexhaustible replacements for traditional batteries in RF identification and wireless sensor network nodes. This paper presents an ultra-low-power integrated RF energy harvesting circuit in a SMIC 65-nm standard CMOS process. The presented circuit mainly consists of an impedance-matching network, a 10-stage rectifier with order-2 threshold compensation and an ultra-low-power power manager unit (PMU). The PMU consists of a voltage sensor, a voltage limiter and a capacitor-less low-dropout regulator. In the charge mode, the power consumption of the proposed energy harvesting circuit is only 97 nA, and the RF input power can be as low as $$-$$-21.4 dBm $$(7.24\,\upmu \hbox {W})$$(7.24μW). In the burst mode, the device can supply a 1.0-V DC output voltage with a maximum 10-mA load current. The simulated results demonstrate that the modified RF rectifier can obtain a maximum efficiency of 12 % with a 915-MHz RF input. The circuit can operate over a temperature range from $$-40\hbox { to }125\,^{\circ }\hbox {C}$$-40to125?C which exceeds the achievable temperature performance of previous RF energy harvesters in standard CMOS process.

RF rectifiers for EM power harvesting in a Deep Brain Stimulating device.

A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 kΩ. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device.