积分梳状滤波器的FPGA实现

为了解决软件无线电通信系统中频采样之后的极大数据量在基带处理部分对DSP计算的压力,常采用多速率处理技术。多速率处理过程中需要使用积分梳状滤波器、半带滤波器和高阶FIR滤波器。在分析了积分梳状滤波器的结构和特性的基础上,阐述了多级CIC滤波器一种高效的FPGA实现方法,该方法的正确性和可行性通过QuartusⅡ的时序仿真分析得以验证,实际中可以推广应用。     

多速率信号处理在通信系统中的应用

讨论了通信系统中多速率信号处理技术,即现应用于软件无线电中的抽样率转换 技术及其具体的实现方法。利用多速率信号处理的方法,降低接收端采样后的数据速率,以减 小后级处理的运算量。针对仿真中由滤波器引起的信号码间干扰失真,提出了两种补偿滤波 器的方案,并通过实例说明了该方案的可行性。     

软件无线接收数字前端的实现

基于软件无线电(SDR)基本思想,提出数字前端概念,对数字前端的组成、功能和基于CORDIC算法的数字下变频、多速率滤波等关键技术进行了介绍。设计了一种软件无线电接收系统,实验表明该设计方案扩展性和移植性好,技术性能达到要求。仿照GSM接收系统技术参数,设计了多速率滤波器,仿真表明,数字前端采用多速率滤波器,能节省成本。对SDR的发展进行了展望。     

基于FPGA的半并行FIR滤波器设计

为了提高FIR滤波器的运算速度和降低的资源消耗,提出了一种新颖的半并行FIR滤波器设计方法,该方法有同定的延时,可以根据滤波器抽头数的不同,得到不同的最高数据输入速率。仿真结果表明,该滤波器设计方法存高速数字下变频器的设计中有较好的性能,并且通过优化设计,可以任一个FPCA实现多个该滤波器模块。     

基于FPGA的半并行FIR滤波器设计

为了提高FIR滤波器的运算速度和降低资源消耗,本文提出了一种新颖的半并行FIR滤波器设计方法。该方法有固定的延时．可以根据滤波器抽头数的不同,得到不同的最高数据输入速率。仿真结果表明,该滤波器设计方法在高速数字下变频器的设计中有较好的性能．并且通过优化设计．可以在一个FPGA实现多个滤波器模块。     

一种新型UWB接收机的设计

利用窄带滤波器设计技术,提出了一种新型UWB接收机设计方法,并定量给出了滤波器中心频率和带宽设计的要求。该方法能够以脉冲重复速率对接收到的信号进行采样,从而有效地降低了系统对A/D器件采样速率的要求及低噪放大器(LNA)的带宽需求,同时其性能也得到了一定的改善。计算机仿真结果表明了该设计方法的有效性。     

高吞吐率任意倍内插滤波器设计

提出了一种高吞吐率用于任意倍内插的并行FARROW滤波器。在串行FARROW内插滤波器的基础上,通过数学推导得出了基于多相分解的并行FARROW内插滤波器。该滤波器由并行FIR滤波器、多输入多输出选择器、累加器和乘加器构成,详细讨论了这些模块在FPGA上的实现方法。仿真试验表明:该并行结构滤波器能够在低时钟速率下提供高吞吐率的任意小数或整数倍内插,实现灵活的采样率变换。     

一种新的CDMA扩展码设计方法

本文首先通过理论分析,给出基于两带镜像多速率滤波器组设计的多值CDMA扩展码的关于循环相关特性的理论性能限及达到此限的条件,说明了基于多速率酉滤波器组设计的扩展码达到了此界限;然后提出了一种基于熵最大化的优化准则来产生CDMA扩展码的设计方法.仿真表明了该方法设计的CDMA扩展码性能的优越性.     

多速率采样中的CIC滤波器设计与分析

CIC滤波器是常用于多速率采样抽取或内插过程中的高效滤波器,具有结构简单,易于工程实现的特点。以提高采样速率为例,首先介绍了内插理论和CIC滤波器原理,重点给出了CIC滤波器设计方法,并分析了CIC滤波器级联级数和滤波器阶数的选取对通带衰减和旁瓣抑制的影响,仿真结果验证了设计方法的有效性和可行性。     

基于多相滤波器组的信道化接收机的分析

该文应用多速率信号处理理论,对基于多相滤波器信道化接收机的数学模型进行了分析和讨论,并与传统的低通滤波法进行了比较,结果表明该方法能以较低的运算复杂度更好的实现信号的实时处理.文章最后用仿真实验结果验证了该方法的正确性.     

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.