功放预失真中自适应算法研究

数字基带预失真技术是补偿功放非线性的最有效方法之一,而自适应算法的选择很大程度上影响着系统的预失真性能。其中,最小均方误差(LMS)算法和递归最小二乘法(RLS)是最常用的自适应收敛算法,LMS算法计算复杂度较低,但LMS算法收敛速度慢,易陷入局部最优且精度不高,RLS收敛性能较好,但计算复杂度高。在综合分析2种算法优缺点的基础上,提出了一种LMS和RLS算法的组合算法,仿真结果表明,组合算法的预失真性能很好,而且算法复杂度较低。     

数字预失真器模型参数辨识算法研究

数字基带预失真技术是补偿功放非线性的最有效方法之一,而自适应算法的选择很大程度上影响着系统的预失真性能。其中,最小均方误差(LMS)算法和递归最小二乘法(RLS)是最常用的自适应收敛算法,在综合分析两种算法优缺点的基础上,提出了一种基于正弦函数的归一化LMS(NLMS)算法和RLS算法的组合算法。仿真结果表明,该组合算法在达到与RLS同样预失真精度的前提下,可大大减小计算量。     

紫外目标探测弱信号处理方法研究

为了提高紫外探测系统性能,研究具有高灵敏性紫外目标探测弱信号处理方法是关键问题之一。首先,在阐述紫外目标探测原理的基础上,分析紫外目标辐射特性。其次,研究自适应噪声抵消信号处理的一般方法,以及基于最小均方误差LMS准则、递推最小二乘RLS准则和线性神经网络ADALINE的三种具体的自适应噪声抵消算法。再次,提出采用功率信噪比来衡量滤波算法的性能。最后,通过仿真计算比较分析这三种算法的滤波效果。结果表明:采用LMS和RLS算法信噪比提高约12.5 dB,且LMS算法比RLS算法略优,而采用ADALINE算法信噪比至少改善26.6 dB,可实现高性能滤波。对于紫外目标探测弱信号处理方法的发展与深入研究具有一定的作用和意义。     

快速启动自适应均衡算法的研究

研究一种快速启动自适应均衡算法,提出并证明了一个命题。计算机模拟结果表明:快速启动均衡算法总是优于LMS算法,固定信道中,性能甚至优于RLS算法;时变信道中,性能接近RLS算法。文中的快速启运自适应均衡算法,具有训练时间较短(与LMS算法比较)、运算简单、容易实现的特点,是一种比较实用的均衡算法。     

自适应滤波算法LMS和RLS及其在应用中的性能

本文介绍了最小均方误差(LMS)算法和递推最小二乘(RLS)两种自适应滤波理论,并在自适应均衡和信道估计两个应用领域中进行了MATLAB仿真结果.     

横向滤波器的自适应算法研究

横向滤波器是数字信号处理中常用的滤波器结构,求解横向滤波器抽头系数的自适应算法主要有最陡梯度(Steepest Gradient)算法、最小均方(LMS)算法、递归最小均方(RLS)算法,前者只具有理论分析意义,后两种是实用的算法。本文比较了上述三种算法的优缺点,并给出了性能分析。     

基于PI迟滞模型的压电陶瓷复合控制算法研究

为减小压电陶瓷的迟滞非线性对系统跟踪精度的影响,该文采用经典的存在逆解析的PI迟滞模型对压电陶瓷的迟滞特性进行建模,将PI模型的逆模型用于压电陶瓷的前馈控制算法中,然后设计了神经元比例、积分、微分(PID)反馈控制算法,将前馈控制算法与神经元PID反馈控制算法结合得到了压电陶瓷的复合控制算法。将仅含前馈的控制算法和复合控制算法在压电陶瓷的控制器上执行,实验结果表明,仅含前馈的控制算法的跟踪误差为1.256 μm,而复合控制算法的跟踪误差仅为0.092 μm,该复合控制算法使跟踪精度提高了1.164 μm。     

基于PI迟滞模型的压电陶瓷复合控制算法研究

为减小压电陶瓷的迟滞非线性对系统跟踪精度的影响,该文采用经典的存在逆解析的PI迟滞模型对压电陶瓷的迟滞特性进行建模,将PI模型的逆模型用于压电陶瓷的前馈控制算法中,然后设计了神经元比例、积分、微分(PID)反馈控制算法,将前馈控制算法与神经元PID反馈控制算法结合得到了压电陶瓷的复合控制算法。将仅含前馈的控制算法和复合控制算法在压电陶瓷的控制器上执行,实验结果表明,仅含前馈的控制算法的跟踪误差为1.256μm,而复合控制算法的跟踪误差仅为0.092μm,该复合控制算法使跟踪精度提高了1.164μm。     

MIMO系统的自适应均衡技术研究

研究了用于MIMO系统的自适应均衡的几种算法，比较了最小均方算法(LMS)、递归最小二乘算法(RLS)、判决反馈算法(DFE)、格型梯度自适应均衡算法(GALE)和格型最小二乘自适应均衡算法(LSALE)。文章的最后给出了仿真结果及结论。     

应用于卫星多波束天线的自适应波束形成算法比较

射频干扰会严重影响卫星通信链路性能,而自适应调零天线是一种有效的卫星抗干扰措施.本文对应用于多波束天线的各种自适应波束形成算法进行对比分析,理论分析与仿真结果皆表明,DMI和RLS算法相对经典的LMS算法而言,在收敛速率和输出信噪干扰比上皆有相当的优越性.这些快速算法适合卫星通信的干扰抑制应用.     

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.