数字线性调频源设计

简要介绍了线性调频信号产生技术的现状,详细介绍了直接数字频率合成(DDS)的基本原理。给出了高性能DDS芯片AD9858的主要特点和配置方法,同时以图形方式给出了基于AD9858芯片硬件结构及互连方法,以及控制DDS芯片的VHDL语言工作波形图,描述了输出线性调频信号的控制流程。     

基于DDS芯片AD9858的雷达宽带调频源的设计

本文介绍了高性能DDS芯片AD9858的主要特点和配置方法，论述了方案的原理和可行性，以图形的方式说明了硬件结构的设计方法．详细描述了输出线性调频信号的控制流程。     

基于AD9858的线性调频信号源设计

AD9858是一款高性能DDS芯片,它集成了10位高速D／A转换器,能够输出频率高达450MHz的正弦波信号。本文详细介绍了AD9858的工作流程及时序关系、寄存器的配置方法,以及基于AD9858的调频信号源硬件设计实现。     

AD9858在捷变频频率合成器设计中的应用

系统地介绍了一种低杂散、低相位噪声、快速捷变频频率合成器的实现途径,用TMS320VC5409控制AD9858得到宽带、低相噪、高SFDR(无杂散动态范围)的输出信号.文中详细阐述了高性能DDS芯片AD9858的主要性能及其应用方法,着重说明了AD9858时钟电路的设计、调试方法,并给出了用PN9000相位噪声仪测试的结果.该数字频率合成器通过编程可方便地实现单点频、线性调频和调相功能, 经过实际应用达到了比较满意的效果.     

时钟3.2GHz直接数字频率合成器的研制

阐述了时钟频率高达3.2 GHz的新型直接数字频率合成器的设计方案,由该方案设计的直接数字频率合成器最高输出频率可达1 500 MHz,并且可以产生线性调频、脉冲步进、调频步进等多种调制信号.通过对该直接数字频率合成器与DDS芯片AD9858进行相位噪声以及杂散进行对比分析,时钟为3.2 GHz的直接数字频率合成器不仅输出带宽得以扩展,其相位噪声在所测试点比AD9858要优10 dB,窄带杂散也较AD9858有很大提高.     

基于AD9858的宽带线性调频源设计

作为高性能DDS单片集成电路,AD9858可方便快速地产生线性调频、单频脉冲信号。现代雷达技术的发展对信号源的性能提出了更高的要求,越来越多的雷达采取宽频带的线性调频信号体制。高性能的AD9858为简化频率源电路设计、提高电路性能提供了一条新的途径。从某频率源的要求出发,介绍了一种宽带线性扫频信号的实现方案,阐述了DDS时钟产生电路、耦合滤波电路、上位机软件功能等方面的设计,进行了必要的仿真,并给出了最终设计的信号源的测试结果。表明AD9858在通信设备、军事以及航空雷达的设计当中是很有应用前景的。     

基于AD9858的线性调频源设计

本文介绍了使用AT89C51作为控制器件,编程控制AD9858,来产生线性调频信号。     

一种基于AD9858的线形调频源设计

介绍了DDS的基本原理、DDS芯片AD9858性能与功能特点,并采用FPGA控制AD9858,实现了线形调频源设计.     

一种高性能DDS芯片的原理与应用

介绍了DDS的基本原理、DDS芯片AD9858功能特点以及芯片的系统结构特点，并采用CPLD控制AD9858，实现了频率合成及宽带信号产生。     

基于DSP控制的直接数字频率合成器的实现

系统地介绍了一种低杂散、低相位噪声、快速捷变频频率合成器的实现途径。提出了使用TMS320VC5409高速DSP作为控制电路，由DDS芯片AD9858构成宽带、低相噪、低功耗数字频率合成器的方案。详细阐述了AD公司最新的内部时钟可达1GHz的高性能DDS芯片AD9858的主要性能及其在快速捷变频频率合成器设计中的应用方法。给出了具体的超宽带应用电路和最终的测试结果，并对如何提高DDS频谱纯度进行了探讨。该数字频率合成器通过编程可方便地实现单点频、线性调频和调相功能，经过实际应用达到了比较满意的效果。     

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.     

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.     

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.     

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.     

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.     

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.