Search Results (46)

A nonlinear state-space model for Schottky diode rectifiers is presented that incorporates junction dynamics, layout parasitic effects, and electromagnetic coupling effects. Unlike prior approaches, the model resolves conduction intervals under harmonic-rich excitation and integrates electromagnetic voltage–current feedback to capture field-induced perturbations at high frequencies. The framework was validated through the design of a 5.8 GHz rectifier, achieving 62% RF–DC efficiency at −10 dBm into a 500 Ω load, with close agreement between the simulation and measurement. The results confirm the model’s predictive accuracy and its utility for high-efficiency rectenna systems in microwave and terahertz applications. Full article

Diamond, renowned for its exceptional electrical, physical, and chemical properties, including ultra-wide bandgap, superior hardness, high thermal conductivity, and unparalleled stability, serves as an ideal candidate for next-generation high-power and high-temperature electronic devices. Among diamond-based devices, Schottky barrier diodes (SBDs) have garnered significant attention due to their simple architecture and superior rectifying characteristics. This review systematically summarizes recent advances in diamond SBDs, focusing on both metal–semiconductor (MS) and metal–interlayer–semiconductor (MIS) configurations. For MS structures, we critically analyze the roles of single-layer metals (including noble metals, transition metals, and other metals) and multilayer metals in modulating Schottky barrier height (SBH) and enhancing thermal stability. However, the presence of interface-related issues such as high densities of surface states and Fermi level pinning often leads to poor control of the SBH, limiting device performance and reliability. To address these challenges and achieve high-quality metal/diamond interfaces, researchers have proposed various interface engineering strategies. In particular, the introduction of interfacial layers in MIS structures has emerged as a promising approach. For MIS architectures, functional interlayers—including high-k materials (Al₂O₃, HfO₂, SnO₂) and low-work-function materials (LaB₆, CeB₆)—are evaluated for their efficacy in interface passivation, barrier modulation, and electric field control. Terminal engineering strategies, such as field-plate designs and surface termination treatments, are also highlighted for their role in improving breakdown voltage. Furthermore, we emphasize the limitations in current parameter extraction from current–voltage (I–V) properties and call for a unified new method to accurately determine SBH. This comprehensive analysis provides critical insights into interface engineering strategies and evaluation protocols for high-performance diamond SBDs, paving the way for their reliable deployment in extreme conditions. Full article

The advancement of microwave wireless power transfer technology has positioned low-power rectennas as a research hotspot. This paper systematically reviews core technological progress in low-power rectennas, focusing on innovations in rectifier circuit topologies, nonlinear device models, antenna array optimization, and efficiency enhancement strategies. Current technical bottlenecks and future application directions are analyzed, providing theoretical references for space solar power stations, IoTs, and related fields. Full article

This paper focuses on hybrid piezo–electromagnetic generators, which are assembled from a magnetic repulsion pad made of two disk magnets, a sliding cylindrical magnet placed inside a tube, a coil, and an assembly of piezoelectric elements connected with the magnetic pad, as well as an electronic system for rectification and voltage adjustment. Four piezo–electromagnetic generators have been developed. Two linear generators without magnetic cores were tested and optimized for low-frequency (0.2 Hz…5 Hz) and low-amplitude body movements. The other two generators were also designed to handle high-vibration amplitudes, to generate up to 2.2–2.5 W of power. An algorithm for the calculation and modeling of these hybrid generators is presented, as well as simulation models. In addition, an electronic hybrid voltage converter was realized. It was observed that the system harvesting efficiency was increased by adding a large capacitive buffer made of electrolytic capacitors after the Schottky diode rectifiers bridges. This capacitive buffer, together with the electronic pre-regulator, has the role of limiting the voltage to the desired input value and of being the first charging stage. Finally, in the second charging stage, an electronic converter is used to charge the supercapacitors. Full article

This paper presents a rectifying metasurface (RMS) that enables wide-angle, polarization-insensitive wireless energy harvesting in the Wi-Fi frequency range. The RMS consists of a metasurface integrated with rectifying diodes, a low-pass filter (LPF), and a resistive load. In the structural design, the RMS incorporates four Schottky diodes placed on the bottom structure and connected to the top structure through four metallized vias. This configuration facilitates impedance matching between the metasurface and the diodes, omitting the need for conventional rectifier circuits or external matching networks and removing the impact of soldering variations. A 3 × 3 RMS prototype was manufactured and subjected to experimental validation. The measurements confirm that the RMS achieves a peak RF-to-DC conversion efficiency of 68.3% at 5.8 GHz with a 12.5 dBm input power, while maintaining stable performance across a wide range of incident angles and polarization states. Full article

Radio-frequency (RF) microwave wireless power transfer (WPT) offers an efficient means of delivering energy to a wide array of devices over long distances. Previous RF WPT systems faced significant challenges, including complex hardware and control systems, software deficiencies, insufficient rectification power, lack of high-performance substrate materials, and electromagnetic radiation hazards. Addressing these issues, this paper proposes the world’s first watt-level RF WPT system capable of intelligent continuous tracking and occlusion judgment. Our 5.8 GHz band RF WPT system integrates several advanced technologies, such as millimeter-precision lidar, the multi-object image recognition algorithm, the accurate 6-bit continuous beamforming algorithm, a compact 16-channel 32 W high-power transmitting system, a pair of ultra-low axial ratio circularly polarized antenna arrays, ultra-low-loss high-strength ceramic substrates, and a 2.4 W high-power Schottky diode array rectifier achieving a rectification efficiency of $66.8\%$. Additionally, we construct a platform to demonstrate the application of the proposed RF WPT system in battery-free vehicles, achieving unprecedented ${360}^{\circ }$ uninterrupted power supply to the battery-free vehicle. In summary, this system represents the most functionally complete RF WPT system to date, serving as a milestone for several critical fields such as smart living, transportation electrification, and battery-less/free societies. Full article

This paper proposes a novel method for the design of arbitrary tri-band rectifiers. This method proposes a novel multiband impedance matching network (IMN) consisting of three Transmission Lines (TLINs), which can realise the matching of source and complex impedance matching in any three bands. For the first time, a network is proposed that realises the second harmonic suppression in three bands using only three TLINs. The Harmonic Suppression Network (HSN) is independent of other parts, which reduces the interaction between TLINs and simplifies the derivation process. For demonstration, the three bands are set to 2.45, 3.5 and 5.8 GHz in the theoretical analysis of closed-form equations. The measured results show that the maximum Power Conversion Efficiencies (PCEs) are 75.4%, 71.2%, and 80.9% at a load of 200 Ω, respectively. This approach to designing compact and efficient tri-band rectifiers has great potential for wireless power transfer applications. Full article

This work presents a numerical analysis of a 2.45 GHz full-wave bridge rectifier for RF (radio frequency) energy harvesting under low-power input conditions, and a guideline for developing a figure of merit (FOM) for RF energy harvester rectennas by relying on data science techniques, laying the foundation for a universally accepted FOM. The performance of the full-wave bridge rectifier, using two types of Schottky diodes, HSMS2850 and SMS7630, was evaluated at −5 and −15 dBm, with the diodes achieving maximum power conversion efficiencies (PCEs) of 57% and 33%, respectively, and reflection coefficient S11 values below −30 dB. A printed circuit board was designed to prepare for future laboratory measurements offering insights into real-world performance. Additionally, a double-voltage rectifier was simulated, achieving PCE values of 41% and 66% at similar input power levels; furthermore, various CMOS-based rectifier topologies reached PCE values of 69% at −5 dBm and 43.6% at −26 dBm. Full article

This paper proposes a terminal matching network (TMN) technology, which can realize wideband matching of microwave rectifiers in a wide input power range. At the same time, it is proposed to realize ultra-wideband microwave rectifiers by connecting two TMN branches of different frequencies in parallel. In order to verify this theory, two rectifiers using single TMN and dual TMN branches are designed and realized based on high-power GaN Schottky barrier diodes (SBDs). The single TMN GaN rectifier achieves a peak efficiency of 72.3% and a conversion efficiency of more than 70% in the frequency range of 1.8–2.7 GHz at 1 W of input power, while being more than 50% efficient in the input power range of 16–35 dBm. Benefitting from the power combination of different frequency TMNs, the dual TMNs GaN rectifier achieves 75.8% peak efficiency and over 70% conversion efficiency at 1.1–3.1 GHz frequency and 1 W input power with a relative bandwidth over 95.2% and maintains high efficiency of over 50% in the input power range of 15–35 dBm. The advantages of the ultra-wideband, wide input power range, high power, and high efficiency make the GaN rectifier with TMNs expected to play an important role in microwave power transmission (MPT). Full article

A novel 2.4 GHz high-efficiency rectifier circuit suitable for working under very-low-input electromagnetic (EM) power conditions (−20 to −10 dBm) is proposed for typical indoor power harvesting. The circuit features a SMS7630 Schottky diode in a series with a voltage booster circuit at the front end and a direct-current (DC)-pass filter at the back end. The voltage booster circuit consists of an asymmetric coupled transmission line (CTL) and a high-impedance microstrip line (of 100 Ω instead of 50 Ω) to significantly increase the potential at the diode’s input, thereby enabling the diode to operate effectively even in very-low-power environments. The experimental measurements show that the microwave direct-current (MW-DC) conversion efficiency of the rectifier circuit reaches 31.1% at a −20 dBm input power and 62.4% at a −10 dBm input power, representing a 7.4% improvement compared to that of the state of the art. Furthermore, the rectifier circuit successfully shifts the input power level corresponding to the peak rectification efficiency from 0 dBm down to −10 dBm. This design is a promising candidate for powering low-energy wireless sensors in typical indoor environments (e.g., the home or office) with low EM energy density. Full article

This paper presents innovations in green electronic and computing technologies. The importance and the status of the main subjects in green electronic and computing technologies are presented in this paper. In the last semicentennial, the planet suffered from rapid changes in climate. The planet is suffering from increasingly wild storms, hurricanes, typhoons, hard droughts, increases in seawater height, floods, seawater acidification, decreases in groundwater reserves, and increases in global temperatures. These climate changes may be irreversible if companies, organizations, governments, and individuals do not act daily and rapidly to save the planet. Unfortunately, the continuous growth in the number of computing devices, cellular devices, smartphones, and other smart devices over the last fifty years has resulted in a rapid increase in climate change. It is severely crucial to design energy-efficient “green” technologies and devices. Toxic waste from computing and cellular devices is rapidly filling up landfills and increasing air and water pollution. This electronic waste contains hazardous and toxic materials that pollute the environment and affect our health. Green computing and electronic engineering are employed to address this climate disaster. The development of green materials, green energy, waste, and recycling are the major objectives in innovation and research in green computing and electronics technologies. Energy-harvesting technologies can be used to produce and store green energy. Wearable active sensors and metamaterial antennas with circular split ring resonators (CSSRs) containing energy-harvesting units are presented in this paper. The measured bandwidth of the matched sensor is around 65% for VSWR, which is better than 3:1. The sensor gain is 14.1 dB at 2.62 GHz. A wideband 0.4 GHz to 6.4 GHz slot antenna with an RF energy-harvesting unit is presented in this paper. The Skyworks Schottky diode, SMS-7630, was used as the rectifier diode in the harvesting unit. If we transmit 20 dBm of RF power from a transmitting antenna that is located 0.2 m from the harvesting slot antenna at 2.4 GHz, the output voltage at the output port of the harvesting unit will be around 1 V. The power conversion efficiency of the metamaterial antenna dipole with metallic strips is around 75%. Wearable sensors with energy-harvesting units provide efficient, low-cost healthcare services that contribute to a green environment and minimize energy consumption. The measurement process and setups of wearable sensors are presented in this paper. Full article

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. Full article

With the escalating demand for Radio Frequency Identification (RFID) technology and the Internet of Things (IoT), there is a growing need for sustainable and autonomous power solutions to energize low-powered devices. Consequently, there is a critical imperative to mitigate dependency on batteries during passive operation. This paper proposes the conceptual framework of rectenna architecture-based radio frequency energy harvesters’ performance, specifically optimized for low-power device applications. The proposed prototype utilizes the surroundings’ Wi-Fi signals within the 2.4 GHz frequency band. The design integrates a seven-stage Cockroft-Walton rectifier featuring a Schottky diode HSMS286C and MA4E2054B1-1146T, a low-pass filter, and a fractal antenna. Preliminary simulations conducted using Advanced Design System (ADS) reveal that a voltage of 3.53 V can be harvested by employing a 1.57 mm thickness Rogers 5880 printed circuit board (PCB) substrate with an MA4E2054B1-1146T rectifier prototype, given a minimum power input of −10 dBm (0.1 mW). Integrating the fabricated rectifier and fractal antenna successfully yields a 1.5 V DC output from Wi-Fi signals, demonstrable by illuminating a red LED. These findings underscore the viability of deploying a fractal antenna-based radio frequency (RF) harvester for empowering small electronic devices. Full article

Energy harvesters provide excellent solutions for the power supply problem of wireless sensor nodes (WSNs), and energy harvesters with a wider bandwidth will clearly better serve WSNs and assist in the construction of Industry 4.0. However, the bearing of rectifiers on the load bandwidth of energy harvesters has rarely been investigated. This paper focuses on the impact of diverse rectifiers on the load electrical response of an electromagnetic energy harvester in the sweep mode of experiments, especially on the load bandwidth. The rectifiers were set as a half-wave rectifier and a full-bridge rectifier, respectively, and two different rectifier diodes were adopted in the experiment. The experimental results suggest that the half-wave rectifier exhibited certain advantages especially in the bandwidth field. If a full-bridge rectifier using high-speed switching diodes is replaced with a half-wave rectifier using Schottky diodes under the load resistance of 100 Ω, the load bandwidth will increase by almost 1.9 times. A preliminary analysis of the experimental results is provided at length. Full article

This review explores the performance and reliability of power semiconductor devices required to enable the electrification of heavy goods vehicles (HGVs). HGV electrification can be implemented using (i) batteries charged with ultra-rapid DC charging (350 kW and above); (ii) road electrification with overhead catenaries supplying power through a pantograph to the HGV powertrain; (iii) hydrogen supplying power to the powertrain through a fuel cell; (iv) any combination of the first three technologies. At the heart of the HGV powertrain is the power converter implemented through power semiconductor devices. Given that the HGV powertrain is rated typically between 500 kW and 1 MW, power devices with voltage ratings between 650 V and 1200 V are required for the off-board/on-board charger’s rectifier and DC-DC converter as well as the powertrain DC-AC traction inverter. The power devices available for HGV electrification at 650 V and 1.2 kV levels are SiC planar MOSFETs, SiC Trench MOSFETs, silicon super-junction MOSFETs, SiC Cascode JFETs, GaN HEMTs, GaN Cascode HEMTs and silicon IGBTs. The MOSFETs can be implemented with anti-parallel SiC Schottky diodes or can rely on their body diodes for third quadrant operation. This review examines the various power semiconductor technologies in terms of losses, electrothermal ruggedness under short circuits, avalanche ruggedness, body diode and conduction performance. Full article