开关电源噪声的形成及抑制方法

开关电源产生的噪声比常规线性电源产生的噪声大得多。介绍了开关电源噪声的类型,分析了开关电源噪声的产生原因,讨论了开关电源中噪声的抑制方法,介绍了几种抑制开关电源中噪声的实用电路。     

高频开关电源的EMC设计

阐述高频开关电源主电路的组成,针对高频开关电源的工作特点,从开关电源中的各组成部分出发,探讨开关电源电路、印制电路板的EMC设计及屏蔽等电磁干扰抑制的方法.通过这些方法的实施,确保高频开关电源满足电磁兼容标准的要求.     

实用电源（3）

常用开关电源还需要分离元件、IC、功率开关元件和专用整流二极管等器件。其中如常用开关电源控制IC,它的出现大大简化了开关电源的设计制作程序。本文主要介绍常用开关电源需要的如常用开关电源控制IC、     

基于DSP控制的数字开关电源综述

简要分析了开关电源的模拟控制方式的特点。为了将数字控制的优点引入开关电源,进一步提高开关电源的性能,文章介绍了一种基于DSP芯片TMS320LF2407控制的数字开关电源。分析比较表明了基于DSP控制的开关电源具有稳定快、失真小、负载对系统影响小的特点,数字控制技术可以在开关电源中推广应用。     

开关电源电磁干扰研究

开关电源应用越来越广泛,但产生的电磁干扰严重影响开关电源效率及其使用。本文分析了开关电源产生电磁干扰的主要原因,并重点给出了相应的抑制措施,以提高开关电源的电磁兼容性。     

高频控制节能型开关电源电路设计与探究

研究的是基于高频控制节能型开关电源电路设计,该设计以开关电源电路为基础,利用芯片控制电路,将开关电源的工作频率提高到相当高的水平,从而满足开关电源在计算机、通信及家用电器等方面日益增长的需求。     

直流开关电源的新技术应用与发展

随着电子技术和通信业的快速发展,高频开关电源的应用越来越广,开关频率的持续提高使开关电源的性能也得以进一步优化,集成度更高,功耗更低,电路更加简单,工作更加可靠,是开关电源发展的方向。目前,高频开关电源在我省广播电视各微波站得到了广泛的应用,基于此结合实际将传统电源与现代高频开关电源对比来介绍高频开关电源的新技术及其优点。     

高压动态测量下数字式LED开关电源设计

由于LED开关电源设计中激光调节过程具有动态性,导致传统设计方法可靠性差。针对该问题,提出一种高压动态测量下的数字式LED开关电源设计方法。利用二阶格型陷波器组建数字式LED驱动的供电信号解析模型,从而得出开关电源的最佳发射功率,根据电源的动态载波值,拟合失真补偿方程,提取开关电源的特征参量,融合LLC原理设计出LED开关电源的主要磁芯元件,给出LED开关电源电路所需的最大增益,得到LED开关电源变压器实际匝比,并计算出变压器电感电量各绕组的线径,以此为依据完成高压动态测量下的数字式LED开关电源的设计。实验仿真证明,该方法的设计精度较高,可以有效地延长LED开关电源的使用寿命。     

一种基于LC振荡器的高效隔离式DC-DC开关电源

设计了一种基于片上变压器的隔离式DC-DC开关电源。通过分析影响开关电源能量转换效率的因素,设计了一种应用于隔离式DC-DC开关电源的LC振荡器,提高了隔离式开关电源的整体效率。采用CSMC 0.35 μm BCD工艺进行设计,并将该振荡器应用于隔离式开关电源。隔离式开关电源的输入电压为3.3 V,输出电压为5 V。仿真结果表明,时钟振荡频率为180 MHz,应用该振荡器的DC-DC开关电源最大输出电流达到62 mA,转换效率提高到35.6%。     

开关电源中特殊保护电路的设计

开关电源工作在高电压下,较大功率的开关电源同时也工作在大电流状态下,并且受到浪涌电流和高压脉冲的威胁,加之开关电源电路复杂,各种不定因素的干扰会影响开关电路的正常工作,因此,开关电源除了一般电子线路的保护电路外,还要设置多种特殊保护电路,以此保证开关电源稳定工作。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

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.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.