VHF 600 W GaN功率模块研制

设计了一种基于GaN HEMT的功率放大模块.该模块采用高增益的GaAs单片、GaN小功率管和GaN大功率管三级级联形式.测试结果表明,模块在约220～270 MHz、工作电压46 V、工作脉宽3 ms、工作比30％的条件下,全带内600 W输出,附加效率大于75％,增益大于52 dB.     

C波段500 kW宽带速调管

在管子输出腔应用重叠模技术,开发了一种C波段宽带速调管,在输出峰值功率500 kW下,瞬时带宽大于4.7%,效率30%,增益43 dB。本文简要介绍了该管的设计研制思想、技术特点、计算模拟和测试结果。     

低压低功耗CMOS电流运算放大器的设计

设计了一种新型CMOS电流反馈运算放大器结构,通过在输出端采用电阻反馈,增强负载能力,利用MOS管实现串联电阻以消除补偿电容带来的低频零点.使用0.5 μm CMOS工艺参数,PSPICE模拟结果获得了与增益关系不大的带宽.电路参数为:80.7 dB的开环增益,266 MHz的单位增益带宽,62°的相位裕度,149 dB共模抑制比以及在1.2 V电源电压仅产生0.82 mW的功耗.     

用于数字电视调谐芯片的高线性CMOS VGA

设计了一种适于DVB-C标准的中频可变增益放大器。该放大器由三部分构成:电流调节型可变增益单元、基于差分对管传输特性的指数控制电压产生电路以及一高线性输出级。采用Chartered0.25μm RFCMOS工艺库下流片。测试结果表明,4～49dB的连续增益范围,100MHz的3dB带宽,50Ω负载下的OIP3为16.8dBm。     

C波段单注宽带速调管的研制

介绍了一种C波段单注速调管的研制工作,包括电子光学、永磁聚焦系统、高频互作用段、输能系统和收集极的设计,并给出了实际测试数据。测试结果显示该管输出带宽达到5.2%,峰值功率达到300 kW,增益大于40 dB,效率大于30%。     

宽频带高增益微带天线元研究

本文提出了一种微带天线元的新结构,它具有宽频带和高增益特性。用谱域法推导了特征方程。用等效电路观点得到输入驻波比的频率特性公式、数值计算设计了一个C波段微带天线元。实测驻波比带宽达16％(VSWR1.5)或25％(VSWR2),增益在10.2～11.3 dB范围。这表明其带宽和增益都比普通微带天线元的带宽(5～6)％和增益(6～7)dB大得多。     

S波段2.5MW宽频带大功率速调管的研制

本文讨论了大功率、高增益、宽频带大功率速调管的设计和制造,还采用小信号增益和大信号效率计算程序,对宽频带速调管的群聚段进行了设计。当小信号增益大于50dB时,7腔速调管的群聚频宽宽于10％,8腔速调管的群聚频宽可达1015％ 给出了两类宽频带输出电路,即滤波器型输出电路和重叠模双间隙腔输出电路的设计方法和测试结果,结果表明:前一种输出电路的频宽可达7.510％,后一种输出电路的频宽可达1015％。 研制了两种类型速调管,采用滤波器型输出段的速调管的性能达到:1dB等激励频宽为7.5％,效率为38％,饱和增益大于43dB,输出功率大于2.5MW。采用双间隙腔输出段的速调管的1dB等激励频宽迟10％,工作稳定。     

一种30 MHz～3 GHz宽带高增益功率放大器

基于0.25 μm GaAs PHEMT 工艺,设计了一种可应用于甚高频和超高频的宽带高增益功率放大器。该功率放大器采用两级级联结构来克服功率增益的不足,采用堆栈结构来实现平坦的增益和输出功率。仿真结果表明,该功率放大器的工作带宽为30 MHz~3 GHz,小信号增益为(38.2±1.6)dB,输入输出回路损耗在-10 dB以下。在连续波测量模式下,输出1 dB压缩点为(35.3±1.0)dBm,功率附加效率为16.8%~11.0%。     

一种-16 dB ~12 dB增益范围的高线性度PGA设计

可编程增益放大器广泛应用于射频接收通道,起中频放大、驱动模数转换器的功能.基于电阻反馈运放设计的可编程增益放大器具有动态范围大、线性度高的特点.文中采用互补金属氧化物半导体工艺设计实现了一种基于全差分运放和衰减器的宽范围、高线性度可编程增益放大器.测试结果表明增益变化范围为-16dB～12dB,步进为1 dB,输出1 dB压缩点大于10 dBm@60 MHz,输出三阶交调点大于26 dBm@60 MHz.     

耦合腔行波管

几年来,贵州凯里国营宇光电工厂对耦合腔行波管的研制和试用方面作了大量工作。他们从理论计算、制管工艺,抑制自激振荡方面进行探讨,找到了有效的抑制方法,取得了较满意的结果。成功地研制出了X波段水冷式周期永磁聚焦耦合腔行波管(见图1),其输出功率大于25kW,瞬时带宽达12％,增益大于32dB、工作比为0.5％。后又根据用户要求、研制出更高频率的风冷式耦合腔行波管系列(见图2),其输出功率分别为10kW和15kW,瞬时带宽为10％、增益大于33dB、工作比为1％。     

GEMNET: a generalized, shuffle-exchange-based, regular, scalable,modular, multihop, WDM lightwave network

GEMNET is a generalization of shuffle-exchange networks and it can represent a family of network structures (including ShuffleNet and de Bruijn graph) for an arbitrary number of nodes. GEMNET employs a regular interconnection graph with highly desirable properties such as small nodal degree, simple routing, small diameter, and growth capability (viz. scalability). GEMNET can serve as a logical (virtual), packet-switched, multihop topology which can be employed for constructing the next generation of lightwave networks using wavelength-division multiplexing (WDM). Various properties of GEMNET are studied     

Thermodynamics of copper matte converting: Part III. Steady-state volatilization of Au,Ag, Pb,Zn, Ni,Se, Te,Bi, Sb,and As from slag,matte, and metallic copper

A comprehensive compilation of various thermodynamic data required for a complete analysis of copper matte converting reactions is presented. The data comprise estimated free energies of formation for such gases as SeO, SeS, TeO, TeS, BiO, BiS, SbO, SbS, AsO, and AsS, as well as activity coefficients in dilute copper alloys and vapor pressures of various elements and compounds. The volatilization of minor elements in steady-state reactors comprising gas and several condensed phases is mathematically formulated, and a parameter which governs the volatilization in such reactors is defined and named volatilization constant. The vapor pressures of various volatile species are calculated thermodynamically for the Noranda Process reactor by assuming equilibrium conditions. The volatilization constants of various minor elements are expressed explicitly as functions of oxygen and sulfur activities. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT     

Bits, symbols, bauds, and bandwidth

The use of clear, concise, and unambiguous language in telecommunications engineering is vital to communicate a desired meaning and understanding. Terminology should be based on rigorous engineering principles and traceable to well known and dependable sources. This article deals with four everyday terms commonly encountered in the popular semi-technical press as well as in serious engineering periodicals. The misuse of these and other terms can lead to low-balled cost proposals, court litigation, and patent infringement cases. Imagine how an engineering student can be confused when she/he typically encounters bandwidth measured in bits per second     

Novel planar, square-shaped, dielectric-waveguide, single-, and dual-mode filters

This paper presents a novel concept of a square-shaped dielectric-waveguide resonator, which can easily realize a dielectric-waveguide cross-coupled filter or a dielectric-waveguide dual-mode filter, using the conventional printed circuit board (PCB) process. This planar dielectric-waveguide resonator has a higher Q value than a microstrip resonator. The physical mechanisms of both single- and dual-mode filters are elucidated. Some new coupling structures are developed for undergoing the PCB process. Filter design procedures are detailed. Design curves for the coupling coefficients of internal- and external-coupling structures are determined by full-wave finite-element-method electromagnetic calculations. Measurement results are highly consistent with theory for all trial filters. This study offers an effective means of producing low-cost high-performance planar circuit filters.     

PBX技术.市态.营销.选购

本文介绍了ＰＢＸ交换机的技术及市场需求态势。并提出ＰＢＸ产品的营销要素及其用户在选购时应遵循的原则。     

Dilemmas,uncertainty, risks,and board performance

This paper traces the origins of the words risk, uncertainty, governance and development and argues that a deeper understanding of each allows more effective decision taking in the boardroom. It argues that the role of the board of directors is to balance and rebalance continuously their irresolvable dilemma — ‘how do we drive our enterprise forward while keeping it under prudent control?’ It argues that it is the board’s role to focus on uncertainty, rather than risk, and this requires a different set of intellectual skills from board members to be able to cope with monitoring a range of diverse scenarios. This is crucial for a board to develop stronger ways of both leading their organisation and of ensuring the connectedness of the learning within and between the board and the operational unit’s risk taking. It advocates that to achieve this a board must develop new ways of learning — especially of thinking strategically and becoming more sensitised to the dynamics of their changing external environments. This will take them well beyond the comforts of their specialist managerial disciplines and into the true world of directing. The paper demonstrates the importance of continuous learning in reducing organisational uncertainty and risk. It uses the ‘Learning Board’ process and model as the central processor of both strategic and operational learning to create an annual rhythm for the board’s year.