Wide bandgap semiconductor transistors for microwave poweramplifiers

Explores the RF power performance of microwave amplifiers fabricated from wide bandgap semiconductor transistors and demonstrates that microwave power amplifiers fabricated from 4H-SiC and AlGaN/GaN transistors offer superior RF power performance, particularly at elevated temperatures. Theoretical models predict room temperature RF output power on the order of 4-6 W/mm and 10-12 W/mm, with power-added efficiency (PAE) approaching the ideal values for class A and B operation, available from 4H-SiC MESFETs and AlGaN/GaN HFETs, respectively. All calculations were thoroughly calibrated against dc and RF experimental data. The simulations indicate operation at elevated temperature at least up to 5000°C is possible. The RF output power capability of these devices compares very favorably with the 1 W/mm available from GaAs MESFETs. The wide bandgap semiconductor devices will find application in power amplifiers for base station transmitters for wireless telephone systems, HDTV transmitters, power modules for phased-array radars, and other applications. The devices are particularly attractive for applications that require operation at elevated temperature     

Power converters and amplifiers (review of "Pulse-Width Modulated DC-DC Power Converters" by Kazimierczuk, M.K.; 2008) [Book news]

This book is a comprehensive textbook in the areas of electrical, electronics, and telecommunications engineering. It consists of 17 chapters and two appendices. Some of the topics covered include: buck PWM DC-DC converters; boost PWM DC-DC converters; buck-boost-PWM DC-DC converters; half-bridge and full-bridge converters; push-pull PWM DC-DC converters; open-loop small-signal characteristics of boost converters for CCM; current-mode control of boost converters; silicon and silicon carbide power diodes; and soft-switching DC-DC converters. Appendix A is an introduction to SPICE and Appendix B provides an introduction to MATLAB. Answers to problems and the index are also included at the end of the book. The book is recommended for senior undergraduate and graduate students but also for practicing engineers working with switch-mode power supplies, within applications such as computers, telecommunications, industrial electronic systems, automobile electronics, medical equipment, radars, and aerospace power technology.     

Feedback Analysis and Design of RF Power Links for Low-Power Bionic Systems

This paper presents a feedback-loop technique for analyzing and designing RF power links for transcutaneous bionic systems, i.e., between an external RF coil and an internal RF coil implanted inside the body. The feedback techniques shed geometric insight into link design and minimize algebraic manipulations. We demonstrate that when the loop transmission of the link's feedback loop is -1, the link is critically coupled, i.e., the magnitude of the voltage transfer function across the link is maximal. We also derive an optimal loading condition that maximizes the energy efficiency of the link and use it as a basis for our link design. We present an example of a bionic implant system designed for load power consumptions in the 1-10-mW range, a low-power regime not significantly explored in prior designs. Such low power levels add to the challenge of link efficiency, because the overhead associated with switching losses in power amplifiers at the link input and with rectifiers at the link output significantly degrade link efficiency. We describe a novel integrated Class-E power amplifier design that uses a simple control strategy to minimize such losses. At 10-mW load power consumption, we measure overall link efficiencies of 74% and 54% at 1- and 10-mm coil separations, respectively, in good agreement with our theoretical predictions of the link's efficiency. At 1-mW load power consumption, we measure link efficiencies of 67% and 51% at 1- and 10-mm coil separations, respectively, also in good accord with our theoretical predictions. In both cases, the link's rectified output dc voltage varied by less than 16% over link distances that ranged from 2 to 10 mm     

改进的高精度功率放大器校准方法

针对当前无线通信系统中,功率放大器的校准效果是衡量一个系统好坏程度的重要指标,因而对功率放大器的校准具有重要作用。本文首先分析了射频模块的系统构成和控制机制,并对系统进行数理建模,将传统射频功率校准的问题转变成参数估值的问题。接着提出了精度和复杂度可控的基于能量守恒的最小均方(LMS)算法,该方法将变量的代数运算限制在一定的范围,而且不需要严格的限制输入数据的分布情况,这对于校准射频信号是极为有利的。仿真结果说明了所提出的算法能有效的将发射功率抑制在0.5dB范围内。     

CDMA基站RF功率放大器的工艺改进研究

介绍了CDMA基站RF功率放大器的基本组成以及预失真技术在放大器中的应用,通过重新分布连接器的位置,改变延迟线的长度从而消除相位偏差.对改善前后的测试数据进行对比,证明了提出改善工艺的方案是有效的,为提高基站RF功率放大器良品率奠定了基础.     

可重构宽带功率放大器设计

随着未来无线通信需求的增长,通信系统需适用更多的频带和标准。 针对可重构功率放大器各模式下工作带宽窄的缺 点,本文基于简化实频技术和可重构理论,提出了一种拓展可重构功率放大器工作带宽的设计方法。 通过在可重构理论中融入 简化实频法的宽带设计方法,在设计过程中加入新的误差函数,对可变模式下的可重构电路结构进行判别,进而实现可重构宽 带功率放大器设计。 为了验证该方法的有效性,并满足实际设计指标,采用中国科学院微电子研究所自主研发的 LDMOS 晶体 管设计并制作了适用于 GSM 网络和 LTE 网络的一个频率可切换的宽频可重构功率放大器。 测试结果表明,该可重构功率放大 器在不同模式下可分别工作在 0. 6~ 1. 1 GHz 和 1. 1~ 1. 6 GHz 频段,饱和输出功率超过 40 dBm,漏极效率(DE)在 50% ~ 60%之 间。 因此,本文提出的设计方法可以降低可重构宽带功率放大器的设计难度,较好的发挥晶体管性能,降低成本,在实际基站射 频电路设计中具有很好的应用意义。     

电能表无线射频集抄系统的研究及前景分析

介绍了远程自动抄表系统及其3种技术方案：RS-485集抄系统、电力载波集抄系统和无线射频（radio frequency,RF）集抄系统,分析了前两种系统分别存在的问题,认为RF集抄系统可作为前两种集抄系统的有效补充,适用于电能表安装比较分散和铺设线路不方便的小区。详细介绍了RF集抄系统在国内外研究、使用的现状及其优缺点,并对其在设计、应用、推广及试验检测等方面存在的相关问题进行了说明。     

开关功率放大器交错并联控制技术的研究

交错链接(Interleaving)控制技术是一种将工作频率相同的多个开关功率变换器单元交错链接的控制策略.能够在不增加功率开关器件应力和损耗的前提下.得到更高的输出功率、更好的输出电压频谱和更小的输出电流纹波.分析了Interleaving控制技术在开关功率放大器中的应用,提出一种较为简便的低成本控制方案,并通过实验进行了验证.     

Power converter design optimization

This article present GA-based design approach to optimization of power electronics circuits is shown to be a very effective and powerful tool for obtaining improved solutions compared to traditional design procedures. In the GA procedure, each design is represented using a "gene string" for the converter design problem, each gene string is used to represent the set of electrical components that define one possible converter design. The design of power electronics systems involves a large number of design variables and the application of knowledge from several different engineering fields.     

Bright idea, radio-frequency light sources

The idea of radio frequency (RF) lighting, as well as the first RF lamp patent, appeared long before the first fluorescent and high-pressure lamps came onto the market. It took over a century for the first commercial RF lamp to appear, introducing a new era in the production of light. Progress in semiconductor power switching electronics, along with a more thorough understanding of fundamental processes in RF plasmas, have resulted in commercially viable RF light sources. RF light sources follow the same basic principles of converting electrical power into visible radiation as conventional gas discharge lamps. The fundamental difference between RF lamps and conventional lamps is that RF lamps operate without electrodes (anode and cathode). This has profound consequences on RF lamp characteristics and features. We consider different kinds of RF discharges and their advantages and restrictions for lighting applications. We also describe examples of successful realizations of different kinds of RF lamps     

Microwave AlGaN/GaN HFETs

This article presents the operating physics, performance potential, and status of device development of microwave AlGaN/GaN heterostructure field-effect transistors. AlGaN/GaN HFETs show potential for use in improved RF performance microwave amplifier applications. Development progress has been rapid, and prototype devices have demonstrated RF output power density as high as 30 W/mm. Microwave amplifier output power is rapidly approaching 100 W for single-chip operation, and these devices may soon find application for cellular base station transmitter applications. Devices are being developed for use in X-band radars, and RF performance is rapidly improving. The HFET devices experience several physical effects that can limit performance. These effects consist of nonlinearities introduced during the high-current and high-voltage portions of the RF cycle. High-current phenomena involve the operation of the conducting channel above the critical current density for initiation of space-charge effects. The source resistance is modulated in magnitude by the channel current, and high source resistance results. High voltage effects include reverse leakage of the gate electrode and subsequent charge trapping effects on the semiconductor surface, and RF breakdown in the conducting channel. These effects can produce premature saturation effects. Also, under certain conditions, high voltage operation of the device can initiate an IMPATT mode of operation. When this occurs, the channel current increases and RF gain is increased. This phenomenon enhances the RF output power of the device. The physical limiting effects can be controlled with proper design, and the outlook for use of these devices in practical applications is excellent.     

软开关功率放大电路及其在高频电刀中的应用

介绍一种采用软开关技术的功率放大电路.该电路能有效地降低功率放大电路中的开关功率损耗,并在相同电源电压的情况下达到更大的输出功率.推导了该电路输出功率的近似解,给出了电路参数的设计公式,并介绍了它在高频电刀中的应用.仿真实验表明,该电路能输出较大的功率和达到较高的效率,非常适合高频电刀的应用.     

Design considerations for photonically integrated antennas [Application Notes]

It is generally well accepted that photonic technology, along with the low-loss, electromagnetic interference (EMI)-free and wide bandwidth signal transport of optical fiber, offers the potential for providing new capabilities, significant performance improvements, as well as design flexibility to analog radio frequency (RF) and microwave systems [1], [2]. The growing spectral demands of current defense systems and new technology opportunities such as high data rate wireless communications offer the possibility of photonics seeing significant technology insertion opportunities in the near as well as the far future.     

Thyristor Controlled, 4300-kW Power Supply System for a Mixed Melter Glass Furnace

An earlier paper described the use of high power thyristors in booster power supplies for glass melting. Since that time, the availability of even larger thyristors has allowed the economical design of larger power supply systems. This paper describes the design features of a 4.3-MW thyristor-controlled power-regulated glass melting power system. The system is installed on a 115-ton mixed melter furnace with bottom electrodes used in the production of opal borosilicate glass. It includes high-voltage switchgear, dual secondary power transformers, and water-cooled power cables along with the thyristor (SCR) equipment. Some information is also presented on electrode peripheral equipment, startup procedures, and a method of computing approximate circuit resistance for use in determining controller and transformer voltage and current ratings.     

Radio waves of progress - [electronics RF]

The development of processes for radio-frequency (RF) operations is heading in two distinct directions. At the same time that process technologies originally proposed for RF are looking more promising as a successor to digital CMOS, so RF designers are expecting to use silicon CMO S even for power amplifiers.     

超高频RFID读写器射频前端的设计

在现行RFID读写器解决方案中,由于直接将A／D变换置于天线端的理想解决方案目前还不可行,天线射频前端的设计是软件无线电实现的关键技术。通过研究射频前端的基本原理,采用基于零中频的软件无线电架构方案。根据EPC协议设计了超高频RFID读写器的射频前端,并给出了使用通用芯片的设计方法,最后进行了测试。测试结果表明：该射频前端的发射功率可达29dBm,系统工作稳定、数据传输准确,达到了预期目标。     

超宽带射频技术对变压器多局部放电源的定位

电力变压器局部放电故障大多是在很短时间间隔内相继出现多个放电源,因此对于多放电源的有效定位是定位技术成功的关键,为解决多点局部放电源的定位问题,采用基于最短光程原理的超宽带射频定位技术,用4阵元传感器阵列检测局部放电源激发的电磁辐射波,获取3个相对时延作为计算参量,利用时间差算法实现对局部放电源空间几何位置进行搜索定位,在实验室环境下进行了空间多点模拟局部放电源的定位试验,多放电源的定位误差控制在10cm以内。此外,还介绍了最近在现场真实设备上进行局部放电定位的探索研究,为该技术向实用化方向的发展做出了有益的尝试。     

Design and analysis of non-uniform shaped RF MEMS switch

In this paper, we present a novel non-uniform shaped cantilever based DC contact radio frequency microelectromechanical systems (RF MEMS) switch. This switch can be employed for various wireless mobile applications in frequency range of DC-10 GHz as it shows excellent RF characteristics with low actuation voltage. The design is optimized in the terms of electrostatic actuation mechanism, which included switch beam thickness, beam gap, spring shape and materials. Also, it’s optimized shape and size of contact geometry and material ensures the high reliability, high isolation and very low insertion loss. The main features of this switch are simplicity of structure, reliability of contact, excellent RF characteristics, low actuation voltage and excellent figure of merit. We investigate the proposed design with Coventorware software for electromechanical and electromagnetic analysis and, get very promising results. The paper briefly outlines the design of RF MEMS switch and also focuses on the analysis of various switching parameters.     

射频电源研究综述

射频电源是可以产生固定频率的正弦波、具有一定频率的高频电源,主要由射频信号源、射频功率放大器及阻抗匹配器组成,射频电源作为等离子体配套电源,广泛应用于半导体工艺设备、LED与太阳能光伏行业、科学实验中的等离子体发生、射频感应加热、医疗美容及常压等离子体消毒清洗等领域.本文梳理了国内外射频电源发展现状,重点分析电子管射频电源及晶体管射频电源的发展历程及主要技术区别,并详述国内外射频信号源、射频功率放大器及阻抗匹配器技术发展.在此基础上,对我国射频电源的发展提出合理性的建议.     

Symbolic Twilight

This article presents the effect of the input nonlinearity in the operation of RF power amplifiers.