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Purpose: Owing to the severity of variation in mechanical excitations of piezoelectric energy harvester, the output energy generated by the system is highly distorted. Hence to maximize the output power a Maximum Power Point Tracking (MPPT) methods are used, which suffers from high output impedance instead of large mechanical impedance. This results in a very low current relative to the high voltages Methods: Hence to state this here a perturb and observe (P& O) based MPPT controller is used with piezoelectric energy harvester. To ensure optimal power generation under diverse operating situations, the maximum power point tracking algorithm (MPPT) was developed. The energy valley optimized perturb and observe algorithm (EV-PO) based MPPT is proposed in this work. The optimum duty cycle is selected with EV and fed to PO as the initial duty cycle to optimize the MPP. Additionally, this work includes a hybrid flyback zeta converter to regulate the rectified output voltage. EV-PO based MPPT algorithm provides the optimal pulses for a DC voltage regulation converter. Results: By this method, voltage is regulated optimally, and the efficiency is increased to 97.63%. This converter is compared with boost, buck-boost, and DC-to-DC converters to show its effectiveness. Along with that the proposed method has resulted in maximum output voltage comparatively with other methods. Conclusion: Overall, the proposed method has improved the efficacy to 7.81% with a DC-DC full bridge converter, 20.1% with buck boost converter, and 21.13% with a boost converter. Thus the adopted method is superior than other existing methods. [ABSTRACT FROM AUTHOR]

A hybrid solar and RF energy harvester is proposed for applications in self-powered wireless sensor nodes. A planar slot antenna array backed by substrate integrated waveguide (SIW) cavity is produced for RF energy harvesting. A designed rectifier connected to the antenna array converts the received RF energy into DC energy. Solar cells are placed on the rest of the antenna array except slots, fully utilizing the array's surface. The solar cell coverage ratio reaches 87%. The measurement results indicate that under solar simulator illumination, the solar energy harvester has a short-circuit current of 15.7 A, an open-circuit voltage of 0.542 V, and a maximum output power of 5.81 W. Under the RF power density of 85.5 μW/cm2, the RF energy harvester reaches its peak power conversion efficiency (PCE) of 69%. All simulated and measured results are in good agreement, verifying the capabilities of the designed hybrid harvester. [ABSTRACT FROM AUTHOR]

This work presents the two port ultra-wide band MIMO antenna with novel isolation structure and dual band RF Rectifier for 3.3 GHz and 4.65 GHz frequencies for RF energy harvesting applications. The anticipated antenna is systematically examined within the ultra-wideband (UWB) range from 3.1 GHz to 10.6 GHz design frequency with four different steps: Antenna 1, Antenna 2, Antenna 3 and Antenna 4 (optimal design) are chosen for comprehensive study. A unique isolation structure was developed between two identical elements separated by 10 mm, resulting in an enhanced isolation of −23.5 dB at 3.15 GHz, −27 dB at 5.8 GHz, −28 dB at 9.26 GHz and greater than −34 dB at 7.5 GHz. The suggested antenna resonates at UWB band and have fractional bandwidth of 118.66 % and a peak gain of 4.1 dB at 3.15 GHz, 3.68 dB at 5.8 GHz, 6.4 dB at 7.5 GHz and 3.2 dB at 9.26 GHz has been obtained. Radiation efficiencies of 92.5 %, 95 %, 90 % and 84.5 % at 3.15 GHz, 5.8 GHz, 7.5 GHz and 9.26 GHz were obtained respectively. The recommended MIMO performance is simulated using HFSS in terms of ECC, DG, MEG and CCL. The results adhere to specified requirements and confirmed by experimentation. An HFSS simulated dataset of reflection coefficient is used as input for the various ML algorithms namely, Support Vector Machine (SVM), Ensemble, k-nearest neighbors' algorithm (KNN) and Gaussian Process Regression (GPR) models are trained with 80 % of the data and testing with 20 % of the data. The test results are compared and corresponding performance values of MAE, RMSE, MSE & R2 are 0.00029, 0.00197, 3.87e−6 and 1.0 validation results and corresponding test results are 0.00031, 0.00229, 5.20e−6 and 0.999. Finally, the proposed dual band rectifier with a shorted stub is tested for harvesting applications at 3.3 GHz and 4.65 GHz frequency and it attained RF to DC conversion efficiencies of 69 % and 55.40 % respectively. [ABSTRACT FROM AUTHOR]

Wireless Power Transfer (WPT) can effectively solve the problem of autonomous power supply for low-power devices. Rectifier is the key component in WPT technology. In this paper, a novel impedance matching network for the broadband rectifier is proposed. This impedance matching network compensates for the diode impedance and reduces its impedance change when the frequency or input power changes. The passive boosting mechanism utilizing coupled transmission lines (CTLs) improves the power conversion efficiency (PCE) of the diode in the low power region. The structure is especially optimized for low-power device applications. For validation, a broadband rectifier operating at 1.9–3 GHz is fabricated and measured. The structure fabricated on the Rogers 4003 substrate with a thickness of 1.508 mm and the diode is HSMS2860. The DC voltage V o u t on the load ( R L = 1300 Ω) was measured. The results show that at 0 dBm, the PCE keeps more than 60% at 1.98–3 GHz. The peak PCE of 79.6% is obtained at 4 dBm. The compact size of the broadband rectifier is 19 mm × 21 mm. This broadband rectifier for low input power ranges can be applied to WPT technology. [ABSTRACT FROM AUTHOR]

In this paper, a complete analysis of an LLC resonant converter with a customized rectifier structure is presented. The converter is intended for wide, low-input, high-output voltage DC bus applications. The performance of the converter is assessed using comprehensive time-domain and fundamental harmonic approximation (FHA), which demonstrates its capacity to operate across an ample range of voltages by precisely adjusting the rectifier structure. The converter's capability is illustrated by deriving and discussing detailed mode operation, steady-state analysis, and DC gain equations. In order to verify the theoretical analysis, a prototype with a power output of 250 watts is constructed and subjected to testing. The results of the testing demonstrate that the converter is both feasible and effective. The experimental findings illustrate its capacity to manage vast voltage ranges while upholding high efficiency. In addition, the converter utilizes a frequency switching modulation (FSM) to connect with a photovoltaic (PV) panel and control the high output voltage. This demonstrates its adaptability in renewable energy applications. The validation is in accordance with theoretical predictions, demonstrating the converter's high-efficiency performance and versatility. [ABSTRACT FROM AUTHOR]

In this work, a novel quad-band rectifier circuit is introduced for RF energy harvesting and Internet of Things (IoT) applications. The proposed rectifier operates in the Wi-Fi frequency band and can supply low-power sensors and systems used in IoT services. The circuit operates at 2.4 , 3.5 , 5, and 5.8 GHz. The proposed RF-to-DC rectifier is designed based on Delon theory and Greinacher topology on an RT/Duroid 5880 substrate. The results show that our proposed circuit can harvest RF energy from the environment, providing maximum power conversion efficiency (PCE) greater than 81% when the output load is 0.511 kΩ and the input power is 12 dBm. In this work, we provide a comprehensive design framework for an affordable RF-to-DC rectifier. Our circuit performs better than similar designs in the literature. This rectifier could be integrated into an IoT node to harvest RF energy, thereby proving a green energy source. The IoT node can operate at various frequencies. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of the characteristics and operating modes of a brushless magneto-electric tachogenerator, which is implemented on the basis of a traditional radial electric machine with a slotless stator and permanent magnets on the rotor. Options for generating an DC output signal using diode and transistor rectifiers have been studied. The dependences of the average value of the output signal, the slope of the output signal, the coefficient of deviation of the characteristic from the specified value and the pulsation coefficient were obtained depending on the rotation speed of the rotor shaft. The influence of the capacitance of the filter capacitor on the magnitude of the output signal ripple amplitude has been studied. Ref. 13, fig. 9, table.

The design of industrial rectifier transformers for use in the field of aluminum production requires the evaluation of the effects of current harmonics in the waveforms, in terms of electromagnetic fields interacting with the transformer's constituent materials. The waveforms of the currents flowing through the windings and high-current output connections of transformers are highly distorted waveforms due to a high presence of harmonics that contribute significantly to the overall losses developed within the system causing overstress of the insulation materials. The evaluation of the electromagnetic effects of these harmonics cannot be approached by means of a time-harmonic steady-state study of the problem, but a time transient must be simulated for a more accurate evaluation. [ABSTRACT FROM AUTHOR]

This article presents three efficient rectifiers for radio frequency energy harvesting (RFEH) systems operating at the fifth generation (5G) band (3.5 GHz). Each rectifier operates at various input power levels (high, low, and across a wide power range). The high and low-power rectifiers feature a single serial topology using HSMS-2860 and SMS-7630 Schottky diodes, respectively, along with microstrip lines to implement the input and output filters and the impedance matching network. At an radio frequency (RF) power level of 15 dBm, the high-power rectifier harvests 67.4% to direct current (DC) power with a 300 Ω load resistor and an output voltage of 2.5 V. The low-power rectifier achieves its maximum power conversion efficiency (PCE) at -2 dBm, reaching 45% efficiency with a 1,200 Ω load. The rectifier with a extended input power range comprises two branches of subrectifiers functioning at both high and low power levels. Depending on the power level, the considered subrectifier harvests radio frequency power into DC power, while the other subrectifier is deactivated. Across a power span of 32.5 dB (ranging from -13 to 19.5 dBm), the rectifier maintains an efficiency above 30%. The proposed rectifiers are efficient and suitable for implementation in 5G-enabled RFEH systems. [ABSTRACT FROM AUTHOR]

This study introduces a novel uninterruptible power supply (UPS) configuration that integrates active power filter (APF) capabilities within a single-phase matrix converter (SPMC) framework. Power disruptions, particularly affecting critical loads, can lead to substantial economic damages. Historically, conventional UPS systems utilized dual separate converters to function as a rectifier and an inverter, without incorporating any power factor correction (PFC) mechanisms. Such configurations suffered from diminished power density, compromised reliability, and spatial limitations. To address these issues, this research proposes an enhanced UPS design that incorporates APF features into the SPMC. The focus of this investigation is on the efficiency of alternating current (AC) to direct current (DC) conversion and the reverse process utilizing this advanced UPS model. The SPMC is selected to supplant the rectifier and inverter units traditionally employed in UPS architectures. A novel integrated switching strategy is formulated to facilitate the operation of the UPS in either rectifier (charging) or inverter (discharging) modes, contingent upon the operational state. The performance and efficacy of the devised circuit design and switching technique are substantiated through simulations conducted in MATLAB/Simulink 2019 and empirical evaluations using a test rig. The findings demonstrate that the voltage generated is sinusoidal and synchronized with the supply current, thereby minimizing the total harmonic distortion (THD) and enhancing both the power factor and the transition efficiency of the UPS system between its charging and discharging states. [ABSTRACT FROM AUTHOR]

In this paper, a CGH40010F GaN-based wideband RF rectifier with high rectification efficiency is presented. A novel continuous class-EFJ-mode rectifier is constructed by combining a continuous class-J-mode rectifier and class-EF-mode rectifier under specific impedance conditions. This novel continuous class-EFJ-mode rectifier has high rectification efficiency and wide bandwidth at the same time. For validation, a wideband high-efficiency class-EFJ-mode rectifier functioning within the 2.0–3.0 GHz range is designed, fabricated, and measured. The measurements indicate that, with an input power of 40 dBm and a resistance of 72 Ω on the dc load, the implemented rectifier sustains a rectification efficiency exceeding 60% across its entire operational frequency band. Meanwhile, the dimensions of the circuits are only 3 cm × 3.1 cm. [ABSTRACT FROM AUTHOR]

A watt‐scale dual‐band rectifier with excellent efficiency and a wide input power range is proposed in this letter. The rectifier is composed of two stages. In the first stage, a novel impedance‐matching network with four transmission lines (TLINs) is proposed, which can independently change the input impedance of each band over a large input power range. This approach by deriving closed‐form analytical equations to obtain an exact solution. To test the parameters of the first part of the TLINs in validation and to guarantee excellent efficiency, two TLINs are used in the second stage to control the harmonics. At 0 dBm, the power conversion efficiency (PCE) is 51.2% and 56.7% at 2.4 and 5.8 GHz, respectively, at a load of 1.2 kΩ. At 2.4 GHz, PCE reaches a peak of 68% at 13 dBm. At 5.8 GHz, PCE enhances up to 89% at 17 dBm. At 2.4 and 5.8 GHz, the PCE exceeds 70% of the peak over a wide input power range of −3 to 18 and 1.5–18 dBm, respectively. For verification, the proposed rectifier is fabricated. The simulation results are consistent with the measurements. The proposed rectifier performs well in terms of compactness and rectification effectiveness. It provides a solution for powering low‐power devices. [ABSTRACT FROM AUTHOR]

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm. [ABSTRACT FROM AUTHOR]

This brief proposes an innovational method to design a broadband high‐efficiency transistor‐based rectifier with high rectification efficiency. The theory of the class‐F−1 rectifier with the input second harmonic component is explored. Moreover, the mathematical variations of rectification efficiency and load/source impedances versus several crucial design parameters are established. The variation relationships indicate that the rectification efficiency can roughly maintain constant across a large input second harmonic range, resulting in more available design impedances. Thus, this provides the possibility to design wideband rectifiers. For validation, a broadband high‐efficiency class‐F−1 rectifier (operating in 1.6–2.6 GHz) using a GaN transistor is designed, assembled, and measured. Measurements indicate a rectification efficiency of between 72.1% and 82.4% under the condition of Rdc = 67 Ω and Pin = 40 dBm. The realized rectifier exhibits the largest relative bandwidth compared with transistor‐based rectifiers reported before. The methodology presented in this brief provides a promising approach for broadband high‐efficiency GaN HEMT‐based rectifiers. [ABSTRACT FROM AUTHOR]

Rectifier plays a pivotal role in wireless power transfer systems. While numerous studies have concentrated on enhancing efficiency and bandwidth at specific high-power levels, practical scenarios often involve unpredictable power inputs. Consequently, a distinct need arises for a rectifier that demonstrates superior efficiency across a broad range of input power levels. This paper introduces a high-power RF-to-DC rectifier designed for WPT applications, featuring an ultrawide dynamic range of input power. The rectification process leverages a GaN (gallium nitride) high electron mobility transistor (HEMT) to efficiently handle high power levels up to 12.6 W. The matching circuit was designed to ensure that the rectifier will operate in class-F mode. A Schottky diode is incorporated into the design for relatively lower-power rectification. Seamless switching between the rectification modes of the two circuits is accomplished through the integration of a circulator. The proposed rectifier exhibits a 27.5 dB dynamic range, achieving an efficiency exceeding 55% at 2.4 GHz. Substantial improvement in power handling and dynamic range over traditional rectifiers is demonstrated. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices. [ABSTRACT FROM AUTHOR]

This article introduces an isolated three-phase six-pulse rectifier using a solid-state transformer. The line frequency utility grid voltage is modulated by a frequency boost converter. This converter exists two parts. The first part is the rectifier section, and the second one is the inverter section. Then after, three-phase diode rectifier is powered by the medium frequency transformer 2 kHz to shrink the transformer size upto 20% or even 10% depensing to the frequency operating range for silicon steel core materials. The aim of this study is to shrink the occupied size of the rectifier using a higher frequency transformer. The study realizes that the grid line current has the same frequency contents as a regular three phase rectifier. In other words, the presented idea results in smaller weight and size while sustaining the performance of input current total harmonic distortion THD=31%. High power density power electronics converter would be extremely valuable for applications such as electric vehicle railways and aircraft. The proposed approach is reliable and easy to use. The solid-state transformer contributes to isolating and improving the overall converter's power density. Simulation results for the 16 kW converter were verified using MATLAB Simulink. [ABSTRACT FROM AUTHOR]

This paper presents a novel adaptive reconfigurable rectifier architecture for radio frequency energy harvesting (RFEH); in addition, a new metric for high-efficiency dynamic range (DR) is proposed. The presented rectifier architecture is based on a double-sided diode-feedback cross-coupled differential-drive rectifier (CCDR) structure incorporating self-body bias for reconfigurable operation. An adaptive structure based on a Schmitt trigger is proposed to adaptively switch the rectifier connection without auxiliary voltage (Vaux), with two rectifier stages in parallel at low power and in series at high power. The system is simulated at a 180 nm CMOS process and the results show more than 17 dB DR at 900 MHz, with efficiency higher than 50% at a 100 kΩ load. [ABSTRACT FROM AUTHOR]

A new type of single–conversion–step wide–input–range versatile step–up/down three–voltage–level power–factor correction stage is presented in this manuscript. The rectifier can operate both in continuous–conduction mode and discontinuous–conduction mode. First, the rectifier's principle of operation is described, and then the innovative rectifier is analyzed in continuous and discontinuous–conduction modes. After, an average model for the innovative rectifier is developed. Lastly, the proposed theory is experimentally validated using a multiplier–less dual–control–loop mode at discontinuous–conduction modes. It is shown that although no multiplier is used in the control circuitry, the power factor is near unity. It is revealed that the rectifier can swing the output voltage from 50 V to 900 V while the input voltage is 230 Vrms. Although the rectifier output has a split DC bus with three voltage levels, the required control effort is low, and the output voltage is balanced. The innovative topology suits any standard power–factor correction rectifier application, dual–stage low–voltage power supply, and three–level voltage supplement for low–harmonic inverters. Since the rectifier's output–voltage swing is extremely wide, energy storage systems and electric vehicle batteries are suitable applications. [ABSTRACT FROM AUTHOR]

The Internet of Things has transformed modern technology relying on sensors powered by batteries. However, the environmental impact of batteries is a significant concern. This paper explores wireless power transfer as a viable solution to this problem. This study focuses on improving the antenna impedance to maximize the performance of the diode on the WPT receiver. The study was made with a numerical and theoretical analysis, simulations, and experimental validations. Moreover, it was demonstrated that the optimum input impedance is high impedance, approaching an open circuit. The paper concludes that designing RF-DC converters with high source impedance leads to an improvement on the rectifying efficiency.

This paper aims to study the effects of impedance mismatch in low-power Radio Frequency Energy Harvesting (RFEH) systems caused by the dependence of Schottky diode input impedance on temperature and propose solutions to mitigate them. Thus, the effects of temperature variation on impedance matching and Radio Frequency (RF) to Direct Current (DC) Power Conversion Efficiency (PCE) will be analyzed through the design, simulation and measurement of an RF rectifier to operate at low input power levels in the 2.4 GHz Industrial, Scientific and Medical (ISM) band in two specific temperature ranges, one around the 300 K (reference ambient temperature) and other around the 325 K (higher temperatures). In order to solve the problem of impedance mismatch due to the temperature dependence of the Schottky diode, the RF rectifier is designed with an Input Matching Network (IMN) with trimming of the stubs in parallel that can be enabled or disabled to set up the desired network and operate according to the temperature of the location. Considering an input power ( $P_{in}$ ) of −20 dBm, the PCE obtained with the prototype configured for room temperature ( $P_{300}$ ) and for high temperature ( $P_{325}$ ) are of 14.73% and 10.53% at 283 K, 16.72% and 16.15% at 303 K, 12.74% and 15.39% at 323 K and 5.82% and 11.67% at 343 K, respectively. As possibly expected by this proposal, the results indicate a higher and more stabler PCE at high temperatures in the prototype configured for 325 K while at room temperature the PCE is higher and more stabler in the prototype configured for 300 K.

Multiple parameter environment monitoring via wireless Internet of Thing sensors is growing rapidly, thanks to low power techniques of the node. More importantly, the ever more complex and highly efficient energy harvesting systems enable long-term continuous monitoring in inaccessible environments without needing to change the battery. This paper reviews existing energy harvesting modalities, including photovoltaic, piezoelectric, pyroelectric, electromagnetic, and vibration, together with circuit techniques of interfacing power management circuits for energy harvesters. Moreover, techniques used to interface with multiple mode energy harvesters to obtain a stable output power with optimal power efficiency are discussed as an emerging direction. The state-of-the-art energy harvesting systems together with future development trends are provided.

In this work, a 2.4 GHz fully woven textile-integrated circularly polarized rectenna intended for wireless power transfer applications is presented. A rectangular patch with truncated corners is used as the radiating element. It is fed through a T-match structure, which allows the control of the input impedance without requiring any additional impedance-matching network. A single-diode rectifier topology was considered to simplify the entire structure and to facilitate its integration with the antenna. The rectifier and the antenna are optimized together through a co-simulation strategy, in which the input impedance of the antenna is adjusted to match the input impedance of the rectifier, ensuring maximum power transfer between them. At the implementation stage, the rectifier is first mounted on a carrier thread, which is then incorporated into the woven structure. This approach, in combination with the chosen antenna feeding technique, which requires no additional elements for impedance matching purposes, provides a high degree of integration between the antenna and the rectifier. The rectenna was experimentally characterized, providing a 45% overall efficiency under realistic working conditions.

This review explores the various strategies used to widen the input power (P $_{\mathrm {IN}}$ ) dynamic range of an RF-DC rectifier and analyzes the recent developments reported in the literature. This development is insightful as the PIN dynamic range is crucial for systems adopting wireless power transfer (WPT) or wireless energy harvesting (EH) for both near- and far-field applications to mitigate the reliance on the battery as its primary power source. However, the RF-DC rectifier exhibits non-linear characteristics, resulting in a narrow PIN band for reasonable power conversion efficiency (PCE). The different strategies reported in the literature are discussed and classified into three main concepts: reconfigurable, multi-path, and self-biased rectifiers. Despite having different design constraints and considerations during the inception of the reported work in the literature, this article analyzes and provides the general development trend, merits, and demerits.

This study introduces a highly efficient harmonic reflection (HR) rectenna designed for precise wireless power transfer (WPT) antenna alignment. The proposed HR rectenna not only converts RF signals to DC power but also transmits a second-harmonic signal to determine the beam alignment between the device and transmitter in diverse environments, including free space and within a medium such as the human body. The proposed rectenna integrates a dual-band slot patch antenna and a HR rectifier. The HR rectifier is configured using a matched voltage doubler and independent second-harmonic impedance control network (ISHICN). To reduce the complexity of the dual-band matching network and mitigate the coupling between the fundamental and harmonic impedances of the HR rectifier, an independent matching technique is applied to a matched voltage doubler and ISHICN, to ensure matching at both the fundamental and harmonic frequencies. Measurement results of the proposed HR rectifier demonstrate impressive performance metrics, including a peak power conversion efficiency (PCE) of 71.6 % at 28 dBm of input power, as well as a peak conversion gain (CG) of -10.4 dB at 8.4 dBm of input power. Notably, the frequency range for PCE >50 % and CG $\gt -22$ dB spans over 0.8 GHz. The antenna adopts a microstrip-fed slot patch design for wide beamwidth at 2.45 GHz and 4.9 GHz, achieving peak gains of 4.9 dBi and 3.8 dBi, respectively. The HR rectenna is integrated with a dual-band microstrip-fed slot patch antenna with sized 60 mm $\times 72.5$ mm. The implemented rectenna is verified to be an efficient WPT receiver through an antenna beam alignment experiment in free space and minced-pork environment.

This paper presents a wireless power conversion system designed for biomedical implants, with integrated automatic resonance tuning. The automatic tuning mechanism improves power transfer efficiency (PTE) by finely tuning the resonant frequency of the power link and maximizing the rectified voltage. This adjustment ensures robust and reliable remote powering, even in the face of environmental changes and process variations, while also minimizing tissue exposure to power. On-chip switched array capacitors are connected in parallel with the resonant capacitor, and the system identifies the optimal switched capacitor combination for the highest rectified voltage by iterating over each of them. The proposed system is implemented and fabricated in standard 180nm CMOS technology, with a total area of 0.339 mm2, and its operation is verified. The measurement results demonstrate that this system provides tolerance up to mismatches equivalent to 75 pF capacitance variation in LC tank, ±15% LC variation in this design. The system offers a PTE enhancement from 9.1% to 30.2% in case of high LC variation, and the tuning control consumes 154.7 $\mu \text{W}$ of power during resonance tuning. Moreover, the power conversion chain delivers an optimized rectified voltage along with a regulated voltage of 1.8 V.

The use of RF harvesting as a power source for low-power systems, such as wearables, wireless sensor nodes, and Internet of Things, has gained attention. The primary obstacle to develop an effective RF-DC system has been the RF rectifier. The method most frequently employed in the design of RF-DC converters is called Cross-Coupled Differential Drive (CCDD). To enhance the DC output voltage, multistage systems are typically employed. In these designs, DC output will reach saturation as the number of stages rises. This is because the NMOS threshold voltage will rise if the bulk of the NMOS is connected to the lowest potential. An alternative is to employ the twin-well CMOS process, which is more expensive than the regular n-well process. A novel CMOS RF-DC converter is presented in this brief. The design is hybrid in the sense the first stage is designed using a standard CCDD, while the second and subsequent stages are designed exclusively with PMOS transistors. This allows the use of the n-well process during fabrication. With CADENCE Virtuoso in $0.18~\mu \text{m}$ TSMC CMOS technology, the suggested design’s functionality is verified. The design is functional and achieves 45% efficiency and a power dynamic range of 23dB for power conversion efficiency (PCE) >20%, according to simulation findings.

In this work, a novel quad-band rectifier circuit is introduced for RF energy harvesting and Internet of Things (IoT) applications. The proposed rectifier operates in the Wi-Fi frequency band and can supply low-power sensors and systems used in IoT services. The circuit operates at 2.4, 3.5, 5, and 5.8 GHz. The proposed RF-to-DC rectifier is designed based on Delon theory and Greinacher topology on an RT/Duroid 5880 substrate. The results show that our proposed circuit can harvest RF energy from the environment, providing maximum power conversion efficiency (PCE) greater than 81% when the output load is 0.511 kΩ and the input power is 12 dBm. In this work, we provide a comprehensive design framework for an affordable RF-to-DC rectifier. Our circuit performs better than similar designs in the literature. This rectifier could be integrated into an IoT node to harvest RF energy, thereby proving a green energy source. The IoT node can operate at various frequencies.

A wide-speed, ultra-light power generation system is a critical power generation unit structure, often because of its high efficiency and power density. Lightness and reliability are two key design indicators within the system, albeit they could lead to contradictory problems, particularly in systems containing prime movers, batteries, generators, rectifiers, and inverters. Ultra-light generator sets are facing more severe problems and contradictions in designing in terms of matching, coordinating, and stabilizing the components in the systems. This paper describes the system design of a low-cost and high-reliability microgenerator set: a gasoline engine, three-phase permanent magnet synchronous generator, rectifier, and inverter. Moreover, the matching relationship between the four parts and the design effect of each part of the power generation system was analyzed, simulated, and tested to verify the effectiveness and feasibility of the so-designed system. [ABSTRACT FROM AUTHOR]

A three-stage rectifier containing three diodes is proposed in this paper. These diodes with different threshold voltages are located in three branches to achieve high conversion efficiency for different input power levels. By combining the three branches, the proposed rectifier is enabled to achieve high conversion efficiency over a wide dynamic input power range. A prototype of a 2.4 GHz rectifier is designed, simulated and measured. The efficiency of the three branches remains above 30% in the power range of-10-11 dBm, 11-24 dBm and 24-35 dBm, respectively. The measured results show that the conversion efficiency maintains over 40% within the input power range of -6-25 dBm, with the maximum conversion efficiency reaching up to 71. 2%. It indicates that the proposed rectifier can achieve low sensitivity to input power variation and high conversion efficiency over an ultra-wide input power range, which can be used in energy harvesting or dynamic wireless power transmission systems. [ABSTRACT FROM AUTHOR]

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In this study, a high-efficiency, high-power synchronous rectifier based on transistors was designed. The widely used diode-based rectifiers have a relatively simple structure but are unsuitable for high-power applications, such as unmanned aerial vehicle and electric vehicle charging. In contrast, transistor-based rectifiers operate by reversing the power flow of a switch-mode power amplifier from the load to the DC supply based on time-reversal duality and can rectify efficiently, even at a high power of 30 dBm or more. The proposed transistor-based synchronous rectifier was designed to have a high rectification efficiency by controlling the harmonics to operate in the inverse Class-F mode and achieved a peak efficiency of 73.2% at an input power of 37 dBm. [ABSTRACT FROM AUTHOR]

Heterostructures of two‐dimensional materials realise novel and enhanced physical phenomena, making them attractive research targets. Compared to inorganic materials, coordination nanosheets have virtually infinite combinations, leading to tunability of physical properties and are promising candidates for heterostructure fabrication. Although stacking of coordination materials into vertical heterostructures is widely reported, reports of lateral coordination material heterostructures are few. Here we show the successful fabrication of a seamless lateral heterojunction showing diode behaviour, by sequential and spatially limited immersion of a new metalladithiolene coordination nanosheet, Zn3BHT, into aqueous Cu(II) and Fe(II) solutions. Upon immersion, the Zn centres in insulating Zn3BHT are replaced by Cu or Fe ions, resulting in conductivity. The transmetallation is spatially confined, occurring only within the immersed area. We anticipate that our results will be a starting point towards exploring transmetallation of various two‐dimensional materials to produce lateral heterojunctions, by providing a new and facile synthetic route. [ABSTRACT FROM AUTHOR]

In this paper, photonic generation of arbitrary shape radio-frequency (RF) waveforms like triangular, square and fullwave rectifier types are demonstrated based on a dual-parallel Mach–Zehnder modulator (DP-MZM) driven by a single sinusoidal RF signal. In the proposed technique, one of the sub-MZM (MZM-2) has no driven signal, while other the sub-MZMs (MZM-1) of the DP-MZM is driven by the sinusoidal RF signal. The powers of even and odd-order sidebands are separately controlled by proper adjustment of modulation index through modulating the bias of the MZM-1. An RF signal with controllable harmonics are generated, after detecting the modulated signal by a photodetector. Thus, by separately modulating its harmonics a desired RF waveform is generated. The proposed method is theoretically analysed followed by experimental validation. [ABSTRACT FROM AUTHOR]

The microwave energy-harvesting (MEH) and microwave power transfer (MPT) technologies have become the most emerging areas of research nowadays. The microwave rectifier circuit is the bottleneck of both the MEH and MPT systems. The efficiency of the system depends on the power conversion efficiency (PCE) of the rectifier. Due to the recent advancement of the fifth-generation communication system, it is desirable to propose an efficient rectifier operating at sub-6 GHz 5G bands. A dual-band rectifier circuit is designed and demonstrated for MEH/MPT purposes, specifically at sub-6 GHz 5G frequency bands. The dual-band matching is achieved by using a stepped impedance transmission line. The rectifier covers N78 (3.3–3.6 GHz) and N79 (4.8–5.0 GHz) bands. Peak PCE of 67.6% @ 3.5 GHz and 56.8% @ 4.9 GHz are achieved. For validation purpose, the rectifier is fabricated and characterized and measured results show good agreement with simulated results. [ABSTRACT FROM AUTHOR]

The paper introduces a new circuit structure of precision full-wave rectifier, without the requirement of any diode(s) and passive component(s), which operates in current mode. The proposed structure of the rectifier employs a single current follower differential input transconductance amplifier and two MOS transistors only. The use of the least number of active components makes the circuit structure simple and favorable to the contemporary integration technology. The proposed rectifier has wider input current dynamic range (±1.6 mA), lower current offset (84 pA), and can operate up to 30 MHz frequency. Additionally, the circuit is easily cascadable, temperature insensitive, and less affected by process variation, MOS transistors mismatch, and supply voltage variation. The rectifier circuit is verified through 0.18 µm gpdk technology-based post-layout simulation results using the cadence Virtuoso tool. The rectification accuracy is examined through the parameters, such as average value ratio and root mean square error. The proposed rectifier's layout measures 31.95 µm × 31.35 µm in size. [ABSTRACT FROM AUTHOR]

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm.

This study introduces a novel uninterruptible power supply (UPS) configuration that integrates active power filter (APF) capabilities within a single-phase matrix converter (SPMC) framework. Power disruptions, particularly affecting critical loads, can lead to substantial economic damages. Historically, conventional UPS systems utilized dual separate converters to function as a rectifier and an inverter, without incorporating any power factor correction (PFC) mechanisms. Such configurations suffered from diminished power density, compromised reliability, and spatial limitations. To address these issues, this research proposes an enhanced UPS design that incorporates APF features into the SPMC. The focus of this investigation is on the efficiency of alternating current (AC) to direct current (DC) conversion and the reverse process utilizing this advanced UPS model. The SPMC is selected to supplant the rectifier and inverter units traditionally employed in UPS architectures. A novel integrated switching strategy is formulated to facilitate the operation of the UPS in either rectifier (charging) or inverter (discharging) modes, contingent upon the operational state. The performance and efficacy of the devised circuit design and switching technique are substantiated through simulations conducted in MATLAB/Simulink 2019 and empirical evaluations using a test rig. The findings demonstrate that the voltage generated is sinusoidal and synchronized with the supply current, thereby minimizing the total harmonic distortion (THD) and enhancing both the power factor and the transition efficiency of the UPS system between its charging and discharging states.