大功率微波真空电子学技术进展

本文综述了近十年来微波真空电子技术进展,由于其在现代军事装备中的重要作用和近十年来技术上取得的进步,使微波真空电子器件在未来30年中仍然是国防装备的核心器件.大功率行波管、微波功率模块(MPM)、多注速调管、回旋管和微型真空电子器件等是正在发展中的重要器件;真空电子器件和半导体器件之间的相互结合与渗透,必将建立兼有两者优点的、性能更加优良的新一代大功率微波电子器件.     

微型真空电子器件和太赫兹辐射源技术进展

微加工技术为真空电子技术的发展提供了新的领域和新的应用.场致发射阵列阴极(FEA)是最突出的代表.本文综述了FEA近年来的发展,特别给出了我所在FEA研究方面的新进展.已经获得5 A/cm²左右的电流密度,为进一步的应用奠定了良好的基础.国际上正在开展微型真空电子器件研究,该项研究将导致微波管体积、重量、成本的降低和工作频率、可靠性的进一步提高.微型真空电子器件可为太赫兹频域提供1W的大功率发射源.     

Kinetic Energy Harvesting Using Piezoelectric and Electromagnetic Technologies—State of the Art

This paper presents the latest progress in kinetic energy harvesting for wide applications ranging from implanted devices and wearable electronic devices to mobile electronics and self-powered wireless network nodes. The advances in energy harvesters adopting piezoelectric and electromagnetic transduction mechanisms are presented. Piezoelectric generators convert mechanical strain on the active material to electric charge while electromagnetic generators make use of the relative motion between a conductor and a magnetic flux to induce charge in the conductor. The existent kinetic piezoelectric generators including human-powered and vibration-based devices are comprehensively addressed. In addition, the electromagnetic generators which include resonant, rotational, and “hybrid” devices are reviewed. In the conclusion part of this paper, a comparison between the transduction methods and future application trends is given.      

真空电子学和微波真空电子器件的发展和技术现状

真空电子学是研究真空中与电子相关的物理现象的学科,主要研究电子的产生和运动、电子与电磁波和物质的相互作用,是各类真空电子器件和粒子加速器等真空电子装置的基础。微波真空电子器件是最重要的真空电子器件,已广泛应用于国防、国民经济和科学研究领域,是军用和民用微波电子系统的核心器件,本文将介绍真空电子学和微波真空电子器件的发展历史,技术现状和应用情况,并对其发展趋势作简要的评述。     

微波真空电子器件的发展与应用

根据真空电子器件的工作原理,其百年发展史可分为三个阶段:以静电控制的普通电子管阶段、以动态控制原理工作的微波真空电子器件阶段、基于相对论效应的新型器件阶段,每个阶段的代表管型在各自的应用领域都发挥了重要的作用。随着电磁波谱的开发利用,微波真空电子器件的技术水平向高频率、高功率、高效率方向发展,推动着军用装备和工业应用的不断拓展,特别在航天领域有长足发展。本文综述微波真空电子器件在厘米波段、毫米波段和太赫兹波段技术发展和装备应用概况,探讨未来的发展方向。     

Introduction, Nov. 1970

After more than five years of intensive research and development, avalanche diodes and transferred electron devices are established as useful and reliable microwave power generators. They have recently been employed increasingly in both military and commercial systems. Many manufacturers now have production capabilities for these devices, and fabrication technology has reached a sophisticated level. Volume production at relatively low cost is now feasible. Avalanche diodes and transferred electron devices now compete favorably on a cost and performance basis with vacuum tubes and solid-state harmonic generators in a wide variety of power-generation applications.     

一种紧凑型大功率微波固态源

传统的微波源主要由行波管、磁控管、返波管等电真空器件实现,但因其工作电压高、功耗大、体积大,导致在使用安全性、利用效率和便携性等方面存在不足。而微波固态源由于具有效率高、谐波抑制性能好、稳定性高等优点,正逐步替代传统微波源,有着很好的发展空间。设计了一种紧凑型大功率微波固态源,采用锁相环作为信源,通过三级功放级联对微波信号进行逐级放大,最终输出频率为915 MHz、功率为300 W 的微波信号。测试结果表明该固态源的工作效率≥70%,二次谐波抑制≤-40 dBc,三次谐波抑制≤-50 dBc。该设计在微波加热和解冻等方面具有很好的应用前景。     

Simulation of a Miniature Coupled-Cavity Slow Wave Structure

Recent development of MEMS technologies has provided a set of methods for mass production of three-dimensional micro-scale structures and have opened the door to new and exciting possibilities in vacuum electronics devices. These micro-fabricated vacuum electronic devices are popular for the advantages of small volume, low cost, good performance, etc. In this article, Cold characteristics of a miniature coupled cavity slow-wave structure are simulated and discussed by using 3-D electromagnetic software MAFIA. The results show that this miniature structure can work at near 1.3 THz with high interaction impedance about 20 ohm and can be expected to be a promising THz radiation source.     

百年电子学--纪念真空电子管发明一百周年

电子学的崛起、发展和广泛应用是20世纪最伟大的科学技术领域之一.在电磁波理论和自由电子发展的基础上,1904年出现了第一只真空二极电子管,一般认为这标志着电子学的诞生.电磁波频谱资源的开发和利用是电子学发展的基础和动力.从电磁频谱统一的观点看,光已经象微波一样进入到电子学的领域,成为无线电电子学中不可分割的组成部分.电子学的基本任务是:研究带电粒子流与电磁场相互作用的物理概念和物理过程,以及利用相互作用的不同物理机制实现粒子与场之间能量有效转化的方法和条件.从电子器件的观点看,电子学可分为真空电子学与固态电子学;而从电子运动规律的观点看,现代电子学将处理自由电子,准自由电子和束缚电子的运动规律及其与电磁场的相互作用.1958年,电子学领域出现三个重要发现和发明:集成电路、激光和相对论自由电子的回旋辐射.相应的,半导体电子学(微电子学)、激光电子学和相对论电子学等现代电子学领域则发端于此.电子器件小型化、微型化、功能集成化将电磁频谱的开拓和占领推向光波和红外毫米波.     

Applications of advanced materials technologies to vacuumelectronic devices

The applications of advanced engineering materials in modern vacuum electronic devices are reviewed. Unique materials with desirable thermal, mechanical, electrical, and magnetic properties are playing a crucial role in raising the average power capability, bandwidth, and efficiency of microwave and millimeter wave amplifiers and oscillators. Five major materials-related topics and technologies are covered in this article: diamond electromagnetic windows and electrode supports; electromagnetically lossy composite ceramics for control of instabilities; methods of cooling metal structures; pyrolytic graphite beam collectors and electron-gun modulation grids; and rare-earth permanent magnets for confining electron beams. For each topic, this article reviews the background physics. describes the importance of the technology to vacuum electronics, presents illustrative examples of how such technologies perform, and reviews current results from the literature     

A Brief Review on Metamaterial-Based Vacuum Electronics for Terahertz and Microwave Science and Technology

Metamaterials, which enable us to realize novel physical effects that cannot be achieved using natural materials, have been extensively studied in recent years and significant progress has been made, especially in the field of optics. This game-changing concept has also initiated a rich variety of research activity in vacuum electronics. Here we review the recent development of metamaterial-based vacuum electronics for terahertz (THz) and microwave science and technology. The reversed Cherenkov radiation (RCR) in double-negative (DNG) metamaterials predicted by Veselago back in the 1960s has been experimentally verified in the microwave frequency range by utilizing specially designed DNG metamaterials. The interaction of an electron beam (e-beam) with DNG metamaterials may lead to the realization of novel applications such as microwave and THz radiation sources, accelerators, and even the visualization of invisibility cloaks. Smith–Purcell radiation (SPR) has recently received renewed interest owing to the development of metamaterials and the concept of spoof surface plasmon polaritons, as discussed in this review, and recent results on e-beam-induced directional and wide-band THz radiation with sharp multiple peaks from a graded grating, as well as directional and monochromatic special SPR and their possible application to THz orotron devices, are also reviewed.     

Investigation of signal spectrum multiplexing in nonlinear structures by means of a quasi-stationary method

The transmission of a complex signal through nonlinear structures (semiconductor diodes, high-power transistor amplifiers, microwave vacuum amplifiers, etc.) is investigated by means of a quasi-stationary method, and functional models of devices are applied. The models use the quasi-stationary method of analysis of multifrequency signal transformation. Certain properties and peculiarities that are exhibited by nonlinear devices and that induce so-called spectrum multiplexing, i.e., formation of combination components, including those observed within the basic spectrum, are considered. The possibilities of spectrum multiplexing in nonlinear elements with a polynomial quadratic, cubic, or more complicated characteristic are discussed.     

Advanced microwave modeling framework exploiting automatic model generation, knowledge neural networks, and space mapping

In this paper, we propose an efficient knowledge-based automatic model generation (KAMG) technique aimed at generating microwave neural models of the highest possible accuracy using the fewest accurate data. The technique is comprehensively derived to integrate three distinct powerful concepts, namely, automatic model generation, knowledge neural networks, and space mapping. For the first time, we simultaneously utilize two types of data generators, namely, coarse data generators that are approximate and fast (e.g., two-and-one-half-dimensional electromagnetic), and fine data generators that are accurate and slow (e.g., three-dimensional electromagnetic). Motivated by the space-mapping concept, the KAMG technique utilizes extensive coarse data, but fewest fine data to generate neural models that accurately match the fine data. Our formulation exploits a variety of knowledge neural-network architectures to facilitate reinforced neural-network learning from coarse and fine data. During neural model generation by KAMG, both coarse and fine data generators are automatically driven using adaptive sampling. The KAMG technique helps to increase the efficiency of neural model development by taking advantage of a microwave reality, i.e., availability of multiple sources of training data for most high-frequency components. The advantages of the proposed KAMG technique are demonstrated through practical microwave examples of MOSFET and embedded passive components used in multilayer printed circuit boards.     

High-power microwave LDMOS transistors for wireless data transmission technologies (Review)

The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10–15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceivers for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).     

High-reliability microwave silicon power transistor with stepped electrode structure and TiN diffusion barrier

A high-reliability microwave silicon power transistor is described that has a stepped electrode structure and TiN diffusion barrier. This structure, used for high-power and high-frequency devices, is discussed by comparing it to the conventional planar structure. The new structure permits microwave devices to achieve high levels of performance. For high-power dissipation devices having a beam lead metal system, however, the Au-Si reaction and localized Pt-silicide growth are major failure mechanisms. To improve these failures, the Ti layer must be thickened and further TiN applications in beam lead metal systems are discussed. Experimental results of high-temperature long-term operations proved that high-power microwave transistors with excellent reliability can be obtained by using a stepped electrode structure with TiN diffusion barrier.     

Microwave plasma devices—Promise and progress

Over the last few years, considerable effort has been devoted to employing the plasma state in applications as widely differing as microwave and optical frequency devices; power generation by thermonuclear fusion; magnetohydrodynamic (MHD) and thermionic energy conversion, and the propulsion of spacecraft. In some of these areas intense activity still continues, and encouraging progress is being made. In others the results have been disappointing, and after an initial period of enthusiasm interest has waned. This paper is restricted to such an area, and reviews microwave plasma device research. A few years ago it seemed that a new and useful range of components, including phase shifters, beam-plasma amplifiers, and harmonic generators, might be developed. After a great deal of work, there is still a dearth of serious commercial plasma competitors to existing vacuum tube and solid-state devices. The paper discusses some of the obstacles to microwave plasma device development that have been encountered along the way, and some of the paths that have been taken to circumvent them. It is concluded that the present disappointing situation is likely to persist unless a major breakthrough is made in production of a simple quiescent plasma source, or there is a departure from the present device concepts.     

SiC and GaN transistors - is there one winner for microwave power applications?

Wide bandgap semiconductors show promise for high-power microwave electronic devices. Primarily due to low breakdown voltage, it has not been possible to design and fabricate solid-state transistors that can yield radio-frequency (RF) output power on the order of hundreds to thousands of watts. This has severely limited their use in power applications. Recent improvements in the growth of wide bandgap semiconductor materials, such as SiC and the GaN-based alloys, provide the opportunity to now design and fabricate microwave transistors that demonstrate performance previously available only from microwave tubes. The most promising electronic devices for fabrication in wide bandgap semiconductors for these applications are metal-semiconductor field-effect transistors (MESFETs) fabricated from the 4H-SiC polytype and heterojunction field-effect transistors (HFETs) fabricated using the AlGaN/GaN heterojunction. These devices can provide RF output power on the order of 5-6 W/mm and 10-12 W/mm of gate periphery, respectively. 4H-SiC MESFETs should produce useful performance at least through X band and AlGaN/GaN HFETs should produce useful performance well into the millimeter-wave region, and potentially as high as 100 GHz.     

Impact of wide bandgap microwave devices on DoD systems

Radiofrequency (RF) semiconductor electronics enable military systems that operate in the microwave and millimeter wave frequency bands of 1-100 GHz. The performance of numerous electromagnetic systems could be enhanced by the inclusion of wide bandgap (WBG) microwave and millimeter wave devices, either as power amplifier or receiver elements. The demonstrated power performance has generally been six to ten times that of equivalent gallium arsenide or indium phosphide devices up through 20 GHz, with enhanced dynamic range and improved impedance matching. These characteristics provide an opportunity to significantly reduce the number of modules required for many active aperture antenna systems, hence, cost, while enabling new capabilities for shared apertures. Prior to realization of any WBG system deployment, however considerable development and maturation of WBG materials, devices, and circuits must yet ensue.     

大功率微波电子注器件及其发展

本文综述了大功率微波管最新进展,指出以电子注和场互作用为基础的大功率微波管,相对论高功率微波源,真空微电子器件是国防和信息系统的核心器件,其技术进展将为２１世纪军事电子装备的发展提供强有力的支持,也将对信息社会产生深远影响。     

Progress in silicon carbide semiconductor electronics technology

Silicon carbide’s demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions is expected to enable significant enhancements to a far-ranging variety of applications and systems. However, improvements in crystal growth and device fabrication processes are needed before SiC-based devices and circuits can be scaled-up and incorporated into electronic systems. This paper surveys the present status of SiC-based semiconductor electronics and identifies areas where technological maturation is needed. The prospects for resolving these obstacles are discussed. Recent achievements include the monolithic realization of SiC integrated circuit operational amplifiers and digital logic circuits, as well as significant improvements to epitaxial and bulk crystal growth processes that impact the viability of this rapidly emerging technology.