Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
To meet the high standard requirements for broadband high-efficiency power amplifiers in modern communication technology, a 6–18 GHz high-efficiency monolithic microwave integrated circuit (MMIC) power amplifier was developed using a 0.25 μm gallium nitride high-electron mobility transistor (GaN HEMT) process. A multistage Chebyshev-filterbased matching approach is utilized to provide the requisite bandwidth while concurrently managing second-harmonic terminations for enhanced PAE. In the final power stage, a multi-cell combining architecture is employed to achieve high saturated output power. The designed GaN amplifier achieves a saturated power of above 43.5 dBm and a PAE of over 30%. The area of the proposed GaN amplifier is 4 × 3.2 mm2. This chip, with its high efficiency and compact size, is promising for high-performance wideband systems....
Power amplifiers are one of the most important microwave components and key equipment in satellite transponder subsystems. It plays a significant role in enhancing the overall capabilities of satellite systems, optimizing thermal design, and ensuring reliability. The rapid development of High Throughput Satellites (HTS) and global mobile communication satellites imposes challenges to power amplifier design. This paper presents a dual-band Doherty power amplifier (DPA) with a hybrid GaN HEMT device and a commercial transistor that can operate simultaneously at 0.9 GHz and 2.14 GHz. At 6 dB output power back-off (OBO), the proposed amplifier achieves drain efficiencies of 42% and 37% at the two frequency bands respectively. When excited by a 20 MHz 16 QAM signal, it exhibits adjacent channel power ratios (ACPR) of −45.4 dBc and −48.6 dBc at output power levels of 34.8 dBm and 34.9 dBm respectively. A novel dual-band offset line structure was employed to achieve the required dual-band load modulation. The proposed DPA is well-suited for application in dual-band wireless communication systems....
The exhaustion of fossil fuels, environmental concerns, and difficulties in deploying smart grids have expedited the development of renewable energy distributed generators (REDGs) and electric vehicles (EVs). In recent decades, there has been a notable rise in the production and marketing of EVs. Previous research has proposed reactive power control solutions, including the use of power electronic converters associated with distributed generators (DGs) to alleviate voltage fluctuations. This research presents a strategy for the best integration of electric vehicles through bidirectional charging and renewable energy distributed generators inside power systems, with the objective of efficiently managing voltage, active power, and reactive power flows at interconnection points. Furthermore, it entails determining appropriate locations and dimensions for electric car charging stations through a comparative examination of computing time and iterations between the Hybrid Genetic Algorithm Improved Particle Swarm Optimization (HGAIPSO) and several other optimization methods, including Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Improved Particle Swarm Optimization (IPSO). This analysis was performed on the IEEE-118 bus system, incorporating Vehicle-to-Grid (V2G), Grid-to-Vehicle (G2V), and REDG allocations. The simulation results indicated that the suggested HGAIPSO approach is more rapid and effective regarding calculation time for complex networks, attaining optimal solutions with greater efficiency....
Transformerless inverters are increasingly becoming essential in renewable energy generation, particularly for grid-connected photovoltaic (PV) and other sustainable and alternative energy resources. The transformerless designs offer higher efficiency, compact size, and reduced cost compared to traditional inverters with bulky transformers. These inverters minimize energy losses and enable direct connection to the grid by removing the low-frequency transformer. This paper investigates a highly reliable single-phase commonground inverter for solar panels and other alternative energy generation. The proposed PV inverter has the benefits of existing non-isolated common-ground PV inverters, including direct connection of an input source’s negative terminal to the AC neutral terminal, eliminating leakage ground currents. The inverter is an enhancement of the dual-buck inverter, incorporating one additional diode and a flying capacitor. The dual-buck structure with the inductor inserted between the inverter phase leg prevents short-circuiting. This increases the reliability of the entire power electronics system. Moreover, using external diodes to freewheel the current, the configuration has no reverse recovery issues, allowing power MOSFETs to be employed with safe commutation at higher DC-link voltage and achieve higher efficiency. Summarily, this design prevents short-circuit issues, enhancing reliability and efficiency, and relaxing pulse-width-modulation dead times. The derivation of the PV inverter is carefully analyzed. A 700W prototype of power converter hardware has been built. The comparative study validates the operational performance, and the grid-connected experiment confirms its theoretical analysis. Experimental results of the hardware prototype are discussed to prove the feasibility and effectiveness of the proposed PV inverter....
The increasing penetration of renewable technologies, particularly photovoltaic (PV) and fuel cell (FC) systems, into microgrid networks has created new challenges in maintaining voltage stability, harmonic performance, and overall power quality. This study presents a comparative evaluation of two modulation and control strategies, which are a Simple Boost Control (SBC) and Space Vector Modulation (SVM). The system is modeled and simulated under standard test conditions (STC) as well as dynamic fluctuations in irradiance to evaluate the inverter performance, total harmonic distortion (THD), and DC-link voltage stability. Simulation findings indicate that although SBC provides structural simplicity and dependable voltage enhancement, the SVM approach delivers greater harmonic mitigation, more seamless inverter performance, and improved voltage utilisation in variable conditions. The results enhance the optimisation of power electronic control systems for renewable energy microgrids, facilitating steady and efficient operation in accordance with South Africa’s green energy goals....
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