Systematic Approach for Design of Broadband, High Efficiency, High Power RF Amplifiers

Abstract

This paper demonstrates a systematic approach for the design of broadband, high efficiency, high power, Class-AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design. As a result, the use of a computer-aided simulation is most often the best way to achieve these goals; however, an appropriate initial value and a systematic approach are necessary for the simulation results to rapidly converge. These objectives can be accomplished with a minimum of trial and error through the following techniques. First, signal gain variations are reduced over a wide bandwidth using a proper pre-matching network. Then, the source and load impedances are satisfactorily obtained from small-signal and load-pull simulations, respectively. Finally, two highorder Chebyshev low-pass filters are employed to provide optimum input and output impedance matching networks over a bandwidth of 100 MHz-500 MHz. By using an EM simulation for the substrate, the simulation results were observed to be in close agreement with the measured results.Keywords: Broadband, Class-AB, Matching network, Power amplifier. Manuscript received June 28, 2016; revised Oct. 7, 2016; accepted Oct. 17, 2016. Seyed Alireza Mohadeskasaei (corresponding author, alireza.kasaee@gmail.com), Jianwei An (ajw626@126.com), Yueyun Chen (chenyy@ustb.edu.cn), Zhi Li (lizhi870218@gmail. com), Sani Umar Abdullahi (umarsani@gmail.com), and Tie Sun (suntie1605@163.com) are with the Department of Communication, School of Computer and Communication, University of Science and Technology Beijing, China. This is an Open Access article distributed under the term of Korea Open Government License (KOGL) Type 4: Source Indiction + Commercial Use Prohibition + Change Prohibition (http://www.kogl.or.kr/news/dataFileDown.do?dataIdx=71&dataFileIdx=2). I. IntroductionPower amplifiers (PAs) are one of the most significant ingredients of many communication systems. Four important requirements, namely, the efficiency, linearity, low noise, and broadband frequency response, must be considered when designing PAs [1]- [3]. For broadband power amplifiers, one of the most difficult challenges lies in determining how to achieve a high signal gain and high power level while maintaining a low power dissipation. In other words, how to achieve high efficiency. At the same time, gain variation throughout the band causes more challenges for modern signal modulation techniques, such as quadrature amplitude modulation.In wideband applications, linear classes, such as Class-A, Class-B, and Class-AB, are widely employed because they provide appropriate bandwidths and acceptable signal gains [4]- [5], but their efficiency is not as high as that of harmonictuned classes, such as Class-E and Class-F [6]- [7]. Various aspects resulting from recent research on broadband PAs are summarized in Table 1. According to this table, a Class-F PA exhibits a high power-added efficiency (P...

Design of a 2.5‐kW L‐band solid‐state pulsed power amplifier for radar applications

“…To achieve the aforementioned required metrics, classic PA classes such as Class‐AB and Class‐C are proper options, while modern classes such as Class‐E, Class‐F, and Class‐J would increase design complexity since they require active devices without embedded pre‐matching networks and a load network with specific impedance even at higher harmonics. Recently, GaN devices are more attractive than other technologies [1], while laterally diffused metal–oxide semiconductor (LDMOS) transistors are still under research and development and capable of providing many advantages such as high stability, high reliability, and low cost [2]. In this Letter, the design and fabrication of a compact, planar, and modular 2.5‐kW high PA (HPA) based on 330‐W LDMOS transistors from NXP Company over 1.2–1.4 GHz is explained.…”