High Efficiency Microwave Power Amplifiers Research Articles

A large-signal scaling model of high-power GaN microwave device

With the rapid development of wireless communications, GaN HEMT, which has various advantages of high power density, high electron mobility, and high breakdown threshold, receiving increasing attention. Microwave power amplifiers based on GaN HEMTs are widely used in many fields, such as communication, medical, and detection instruments. In the accurate design of GaN microwave power amplifiers, reliable RF large signal model is vitally important. In this paper, a scalable large-signal model based on EEHEMT model is proposed to describe the properties of multifinger AlGaN/GaN high electron mobility transistor (HEMT) accurately. A series of scaling rules is established for the intrinsic parameters of the device, including drain-source current <i>I</i><sub>ds</sub>, input capacitance <i>C</i><sub>gs</sub> and <i>C</i><sub>gd</sub>, which take into account both the gate width of a single finger and the number of gate fingers. With the proposed scalable large-signal model, the performance of the L-band GaN high-efficiency power amplifier with a gate length of 14.4 mm is analyzed. This amplifier demonstrates outstanding performance, with the output power reaching to 46.5 dBm and the drain efficiency arriving at over 70% of the frequency range from 1120 MHz to 1340 MHz. Good agreement between the simulations and experiments is achieved, demonstrating the excellent accuracy of the proposed model. Moreover, the proposed model can further predict the performance of high-order harmonics, providing an effective tool for designing advanced high-power and high-efficiency microwave power amplifiers. Certainly, the EEHEMT model fails to characterize the dynamical behavior induced by trapping and self-heating effects. Thus, for further consideration, scaling models for the thermal resistance and heat capacity need further investigating to broaden the application scope of the proposed model in the case of continuous waves.

Design Theory and Techniques for High Efficiency Microwave Power Amplifiers Used in SSPS

Design Theory and Techniques for High Efficiency Microwave Power Amplifiers Used in SSPS

Medición de las formas de onda en la caracterización de dispositivos de microondas: impacto en el diseño de amplificadores de potencia

Este artículo describe un ejemplo de setup, para la medición de las formas de onda durante la caracterización load-pull de un dispositivo de microondas con alta capacidad de potencia. La significancia de está característica de la medición, se resalta al estudiar la forma en la cual puede ser utilizada, en el diseño de amplificadores de microndas con altas potencias de salida y alta eficiencia.

Experimental Design Method for High-Efficiency Microwave Power Amplifiers Based on a Low-Frequency Active Harmonic Load-Pull Technique

Experimental Design Method for High-Efficiency Microwave Power Amplifiers Based on a Low-Frequency Active Harmonic Load-Pull Technique

Optimum design of very high-efficiency microwave power amplifiers based on time-domain harmonic load-pull measurements

Due to the large expansion of wireless communications, the need for high-efficiency power amplifiers has emerged. In mobile communication systems, power amplifiers are the most critical elements for the power-dissipation budget. Thus, the operating conditions of active devices have to be optimized using accurate and complementary computer-aided design (CAD) and experimental tools. This paper reports two design methods of high-efficiency power amplifiers. The first one is CAD oriented and based on the substitute generator technique using the nonlinear model of transistors. The second one is based on a specific measurement system of time-domain waveforms using a modified vector network analyzer, coupled with harmonic active load-pull techniques (three active loops). This new setup enables the measurement and optimization of time-domain waveforms at both ports of transistors driven by constant-wave test signals. These two design methodologies are applied to the optimization of an S-band 1-W class-F GaInP/GaAs heterojunction-bipolar-transistor power amplifier.

Measurement and control of current/voltage waveforms of microwave transistors using a harmonic load-pull system for the optimum design of high efficiency power amplifiers

One of the most important requirements that RF and microwave power amplifiers designed for radiocommunication systems must meet is an optimum power added efficiency (PAE) or an optimal combination of PAE and linearity. A harmonic active load-pull system which allows the control of the first three harmonic frequencies of the signal coming out of the transistor under test is a very useful tool to aid in designing optimized power amplifiers. In this paper, we present an active load-pull system coupled to a vectorial "nonlinear network" analyzer. For the first time, optimized current/voltage waveforms for maximum PAE of microwave field effect transistors (FET's) have been measured. They confirm the theory on high efficiency microwave power amplifiers. The proposed load-pull setup is based on the use of three separated active loops to synthesize load impedances at harmonics. The measurement of absolute complex power waves is performed with a broadband data acquisition unit. A specific phase calibration of the set-up allows the determination of the phase relationships between harmonic components. Therefore, voltage and current waveforms can be extracted. The measurement results of a 600 gate periphery GaAs FET (Thomson Foundry) exhibiting a PAE of 84% at 1.8 GHz are given. Such results were obtained by optimizing the load impedances at the first three harmonic components of the signal coming out of the transistor. Optimum conditions correspond to a class F operation mode of the FET (i.e., square wave output voltage and pulse shaped output current). A comparison between measured and simulated current/voltage waveforms is also presented.

AlInAs/GaInAs on InP HEMTs for low power supply voltage operation of high power-added efficiency microwave amplifiers

High power-added efficiency microwave power amplifier results are reported for AlInAs/GaInAs on InP HEMTs operated at relatively low power supply voltages (2.5–3 V). C-band power amplifiers are reported with power-added efficiencies as high as 67%, and output powers between 200 and 300 mW. This excellent performance at low power supply voltages is attributed to the high gain and low access resistances of the devices, which leads to a high drain efficiency despite the low power supply voltage.