LVDS技术在数码音响中的运用

LVDS(Low Voltage Diffrential Signaling)低压差分信号技术,是目前数字化进程中的热门技术。数字视频、数字通信等许多领域都争着引用这一技术。LVDS开初主要用于笔记本电脑图形控制IC和LCD接线版的连接,或用于连接外部LCD的图形接口等高频数码流的传输。 图形数码流显然属于高频范畴。我们知道,随着传输信号频率的增高,传送信号的导线将向空间辐射电磁波,这种“类天线”的辐射效应就是EM1电磁干扰源。反过来,外部干扰信号也会因这种“类天线”效应窜入导线,这种电磁干扰,频率越高越严重。使用LVDS就可避免这类干扰,提高数码流的传输质量。     

电力系统中的光纤通信

光纤通信具有不受电磁干扰,不用高压,不用接地、安余等特点,特别适用于电力系统。因为电力系统传输电话或控制信号是在特殊环境中进行的。一种是从高电化区将测量信号传输到地面。例如电网冲击负载测量信号。在高电位区测得的信号,通过光电转换(用测量信号     

卫星传输空间电磁干扰问题研究

卫星通信技术已经成为广播电视重要的传输手段,是国家舆论战线的主阵地,对卫星通信信号的质量有极高的要求。而卫星信号传输距离远,在传播过程中容易受到传输空间的各种干扰,严重影响信号质量,其中传输空间电磁干扰是对卫星传输信号影响较大的一种,本文主要就卫星传输空间电磁干扰问题进行分析,探讨抗干扰措施,提高卫星通信信号质量。     

燃料电池车用大功率DC／DC变换器电磁兼容性研究

本文对燃料电池电动汽车用大功率DC/DC变换器的电磁干扰源及传输途径进行深入分析,从抑制大功率DC/DC变换器的电磁干扰、控制电路PCB板信号隔离以及软件程序抗干扰三个方面进行大功率DC/DC变换器的电磁兼容性研究,给出抑制燃料电池电动汽车用大功率DC/DC变换器电磁干扰以及提高控制电路板及软件程序抗干扰能力的具体措施,为整车的可靠运行提供了保障.     

直流高压电源束流调节保护电路研究

本文介绍了一种用于直流高压电源的束流调节保护电路。该电路具有多重保护措施,包括电容对强干扰的抑制、压敏电阻的电压钳位以及二极管限幅电路等。束流检测信号经保护电路连接到束流调节器,通过对束流信号进行运算放大,并与保护阈值电压进行比较,确定输出过流信号,触发单向可控硅,控制继电器的吸合,从而实现电源电路保护的目的。仿真和实验结果表明,该电路结构合理、灵敏可靠,为电源电路系统的安全运行提供了有效的保障。     

束流聚焦影响因素的束矩阵法计算分析

利用束矩阵的数值计算方法，研究了束流在聚焦系统中的传输行为和系统磁场位形的关系，重点探讨了入射束流不同初始参数对打靶聚焦的影响。计算结果表明，对于不同初始参数(尤其是在相空间的不同初始状态)的束流，要分别聚焦在靶上需要选择不同的磁场位形；主磁透镜的场强及其位置是调试束流聚焦的关键因素。同时还计算给出了几种能使束流聚焦焦斑半径在1．5mm以下的磁场位形。     

射电天文台站准实时电波环境测量方法

随着频率使用率的提高,瞬态信号对射电天文观测影响越来越大,有效的电波环境测量及频谱分析可为现有射电天文台址干扰缓解策略提供依据.基于现有射电望远镜台站电波环境特征,结合信号分析仪原理,深入分析了仪器设备关键参数配置方法及测量时间计算方法;结合实际测量需求,确定了测试时间规划策略,提出一种准实时电波环境测量方法.运用此方法对新疆天文台南山台站电波环境进行测量,分析了频谱、频率占用度随时间变化特点,结果表明,该方法能够有效分析电磁干扰随时间的变化趋势.     

电磁干扰测量与诊断

电磁干扰是一种不希望存在的信号,它对电子设备或系统的正常工作会造成有害影响。同时,每一种电子产品都会产生电磁干扰信号,这些信号可能以电磁辐射的形式发射出去。也可能通过电缆或电源线传播。电磁干扰的产生应具备三个条件:传播和辐射电磁波的源,电磁波借以传播的媒介,因接收到了信号而受到干扰的干扰器。三者只要消除一个,就不会产生电磁干扰。所以,诊断和消除电磁干扰是我们必须解决的问题,要解决电磁干扰问题,首先要能够"看"到电磁干扰,了解电磁干扰的幅度和发生源。本文要介绍有关电磁干扰测量和判断干扰发生源的方法。     

离子注入机的辐射剂量

一、引言随着器件工艺的不断发展,对离子注入机提出了更高的要求,70年代初的离子注入机只能获得几十微安的束流,称为弱流离子注入机。近年来,广泛采用的是中束流离子注入机,束流可达几百微安,能量一般在200kev以下。同时束流达毫安级的大束流离子注入机,能量在100kev以下,也得到迅速的发展。随着束流的提高,注入剂量的增大,离子注入机的辐射剂量也随之增大。测量结果表明,离子注入机的辐射线主要是X—γ射线,为了减少辐射线对工作人员的危害,并为设计离子注入机提供一些参数,我们对我所生产的LC_2和LC_3型离子注入机,以及国内现有部分离子注入机的辐射剂量进行了较全面的调查和测量.本文简要介绍我们的调查和测量结果。     

一种新型最佳接收机设计方法

提出了一种提高接收机性能的新方法。该方法通过对信道传输信号波形的特征参数测量,分析传输信号的成形方式,根据成形参数设计最佳接收滤波器,有效降低码间串扰和信道噪声对接收机性能的影响,并在噪声信道环境下进行了仿真研究,使用了采样统计方差、信噪比和眼图3种方法对接收机性能进行分析,结果表明,该方法能够有效提高接收机的性能。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.