机载雷达伺服系统设计

介绍了某机载雷达伺服系统，对其工作原理、基本结构、控制方案、驱动技术等进行了分析探讨。设计了无刷直流电动机PWM控制器、角位置检测等硬件电路以及位置、速度、电流三环控制系统。实验结果表明，该系统通过硬件和软件的合理设计，具有较好的动、静态性能。     

小容量直流电动机的单片机数字直接控制

采用计算机实现电气传动系统的数字直接控制(DDC)是当今的发展方向.本文作者研制了一种小容量直流电动机的单片机DDC系统.在系统中,单片机完成了晶闸管触发、控制运算以及故障诊断等功能,并设计了新型隔离器对主电路的直流电压进行隔离,以获取反馈电压.实践结果表明,本系统具有优良的技术性能:调速范围D=10,静差率S≤2％.     

浅谈数字化直流驱动器在焊管轧机速度控制中的应用

引进的Φ２１９直缝焊管机组中，主轧机驱动部分使用了４台２００ＨＰ直流电动机，采用数字化直流驱动装置，利用编码器反馈的速度控制方式，对电机运转速度进行调整和控制，使得各电机之间的同步调整十分方便，焊管机组运行稳定可靠。     

热轧带钢精轧主机电控系统改造

宣钢一轧厂热带车间先后于１９９６年和１９９７年对六台精轧直流主电机Ｆ１至Ｆ６之中的三台Ｆ４、Ｆ５、Ｆ６的电控系统进行了数字化改造。经过一年多的运行，在热带车间中已经体现出了明显的效果，并产生了一定的经济效益。     

大型直流电机换向器的维护

直流电机换向器的维护是直流电机维护工作的核心部分。大容量直流电机是轧钢车间的主体设备,对其换向器的维护工作更显得重要。本文着重介绍了冶金企业轧钢车间大型直流电机换向器的现场维护工作和体会。     

Low-Cost Testing of 5 GHz Low Noise Amplifiers Using New RF BIST Circuit

This paper presents a new low-cost RF BIST (Built-In Self-Test) scheme that is capable of measuring input impedance, gain, noise figure and input return loss for a low noise amplifier (LNA) in RF systems. The RF BIST technique requires an additional RF amplifier and two peak detectors, and its output is a DC voltage level. The BIST circuit is designed using 0.18 μm SiGe technology. The test technique utilizes output DC voltage measurements and these measured values are translated into the LNA specifications such as input impedance and gain using the developed mathematical equations. Simulation results are presented for an LNA working at 5 GHz. Measurement data are compared with simulation results to validate the developed mathematical equations. The technique is simple and inexpensive. Jee-Youl Ryu received the BS and MS degrees in 1993 and 1997 from Pukyong National University in Electronic Engineering, Pusan, South Korea respectively. He also received the PhD degree in 2004 from Arizona State University in Electrical Engineering, Arizona, USA. He is currently with Samsung SDI Co., Ltd. His current research interests include RF IC design and testing, MMIC design and testing, analog IC design and testing, passives modeling, testing and analysis, and MEMS technology. Dr. Bruce Kim received the B.S.E.E. degree from the University of California, Irvine in 1981, the M.S. degree in electrical engineering from the University of Arizona in 1985, and the Ph.D. degree in electrical engineering from Georgia Institute of Technology in 1996. He was an Associate Professor at Arizona State University until 2005. Currently, he is an Associate Professor at The University of Alabama. His current research interests include RF IC testing, MEMS integration and VLSI circuits. He has been working on SiP testing technologies, package electrical modeling, and measurements of RF IC packages. Dr. Kim is a 1997 recipient of the National Science Foundation's CAREER Award and received the Meritorious Award from IEEE. He serves as the Chair of the IEEE CPMT Society TC-Electrical Test, associate editor of the IEEE Transactions on Advanced Packaging, associate editor of Design and Test of Computers, and program committee member of Electronic Components and Technology Conference. He is a senior member of IEEE.     

Comparative Assessment of Adaptive Body-Bias SOI Pass-Transistor Logic

A very low voltage transconductor for video frequency range applications and compatible with standard CMOS technology is described. In the proposed transconductor, except the DC level shifter circuit (DCLS), the whole transconductor uses the main supply voltage [which can be as low as 1.5 V in a standard 0.6 μm CMOS technology] while the DCLS uses a simple charge-pump circuit as its supply voltage and has a very low current consumption. In addition, proper common-mode sense and charge-pump circuits are developed for this low-voltage application. Meanwhile, some techniques to improve the frequency response, linearity, and noise performance of the proposed transconductor are described. In a standard 0.6 μm CMOS technology and single 1.5 V supply, simulations show that the proposed transconductor futures a THD of −50 dB for 1.4 V_pp and 10 MHz input signal and −60 dB for 1.4 V_pp and 1 MHz signal where the threshold voltage of MOS transistors could be as high as 1 V. Based on the proposed transconductor, a lowpass filter with 700 kHz to 8 MHz programmable cutoff frequency and a bandpass 10.7 MHz second order filter were implemented. Armin Tajalli received the B.Sc. from Sharif University of Technology (SUT), Tehran, Iran, in 1997, and M.Sc. from Tehran Polytechnic University, Tehran, Iran, in 1999. From 1998 he has joint Emad Co. as a senior design engineer were he has worked on several industrial and R&D projects on analog and mixed-mode ICs. He received the award of the Best Design Engineer from Emad Co., 2001, the Kharazmi Award of Industrial Research and Development, Iran, 2002, and Presidential Award of the Best Iranian Researchers, in 2003. He is now working toward his PhD degree at SUT. His current interests are design of high speed circuits for telecommunication systems. Mojtaba Atarodi received the B.S.E.E. from Amir Kabir University of Technology (Tehran Polytechnic) in 1985, and M.Sc. degree in electrical engineering from the University of California, Irvine, in 1987. He received the Ph.D. degree from the University of Southern California (USC) on the subject of analog IC design in 1993. From 1993 to 1996 he worked with Linear Technology Corporation as a senior analog design engineer. Since then, he has been consulting with different IC companies. He is currently a visiting professor at Sharif University of Technology. He has published more than 30 technical papers in the area of analog and mixed-signal integrated circuit design as well as analog CAD tools.     

Dielectric Properties of Niobium and Lanthanum Doped Lead Barium Zirconate Titanate Relaxor Ferroelectrics

The lead barium zirconate titanate (PBZT) relaxor ferroelectrics are ideal for high voltage capacitor applications due to their high dielectric constant, stability under DC bias, and temperature stability. In this study the composition (Pb_0.65Ba_0.35)(Zr_0.70Ti_0.30)O₃ was selected as the base composition. It exhibited typical relaxor characteristics such as frequency dispersion and diffuse phase transition. The dielectric constant is 6000 at room temperature and remains almost constant under electric field as high as 20 kV/cm. To further enhance the dielectric properties, various amounts of niobium oxide and lanthanum oxide dopants were added to the base PBZT to alter the defect structure and hence the dielectric properties. It was found that the dielectric constant of 1% Nb-doped samples was increased by 20–25% while maintaining similar voltage stability. This increase was attributed to the abnormal grain growth in the Nb-doped sample, and the correlation between microstructure and dielectric constant was drawn through a grain size study. The La addition only caused a monotonic decrease of dielectric constant and slightly improved voltage stability.