一种新颖的1.5 V CMOS 4FSK解调电路

为了减小 4进制频移键控信号 ( 4FSK )解调电路的复杂性 ,提高解调输出的准确性 ,文中提出了一种可以在 1.5V下工作 ,标准 CMOS工艺实现的 4 FSK解调电路。该解调电路采用一个基准电压 ,利用绝对值比较的特性解调出 4 FSK频移键控数字信号     

一种FSK信号调制解调电路的设计

介绍了一种FSK信号调制解调电路的设计思想,发送端采用锁相环芯片CD4046实现了基带信号的FSK调制,接收端采用普通鉴频法进行解调,将FSK信号转换为ASK信号,并采用检波和低通滤波电路恢复出其基带信号。该电路具有结构简单、成本低廉、工作可靠等优点,可适用于低速电力线载波通信中。     

RFID芯片T5557及其FSK读写器电路设计

T5557是兼容e555x的RFID芯片，但又具有与e555x系列芯片不同的新性能。文章着重介绍了T5557的新特点及工作原理，并对其FSK工作模式下读写器的电路设计作了分析，最后给出了D类功放和FSK解调的应用电路。     

433/868/915MHz FSK/ASK/OOK无线收发器RF2945

RF2945是RFMicroDevices公司生产的一种单片射频收发芯片,利用该芯片可在433/868/915MHzISM频段进行FSK/ASK/OOK调制和解调。由于RF2945射频收发芯片内含射频发射、射频接收、PLL合成和FSK调制/解调等电路,因而可用于接收和发送数字信号。文中介绍了RF2945的结构原理和主要特性 ,同时给出了RF2945收发器的典型应用电路和使用注意事项     

一种能满足通抗侦察要求的2FSK解调电路

由于2FSK信号在信息传输效率与抗噪声性能方面的优势,在军事通信和国际电报通信中大量被采用。对2FSK信号的分析与识别是通抗侦察的重要内容,而常规的2FSK信号解调电路无法满足通抗侦察的需求,本文介绍的解调电路克服了常规解调器的问题,适应对未知2FSK信号进行侦察的要求。     

移频键控信号的取样判决解调法

移频键控信号(简称FSK信号),可以用任何一种连续频调波解调器进行解调.但由于FSK信号只在两个固定的频率上跳来跳去,所以它的解调可以简化,从而FSK信号的解调还有一些特殊的方法如滤波法、计数法、…等.这里介绍一种用取样判决的方法解调FSK信号.这种方法具有电路简单、对不同频率的信号调整比较方便,便于做成集成电路.     

基于FPGA的FSK调制解调器设计

数字通信系统中的数字调制与解调技术包括幅度键控(ASK)、频移键控(FSK)和相移键控(PSK),而FSK是应用较广的一种调制与解调方式。利用VHDL语言设计了2FSK调制解调器,并通过QuartusⅡ仿真平台进行仿真验证,最后下载到FPGA芯片EP1K30QC208-2实现了2FSK调制解调电路。仿真及实验结果表明采用此设计方案是可行的,并具有速度快、可靠性高及易于大规模集成的优点。     

DSTFT在应答器信号解调方面的应用研究

应答器2FSK信号的解调大多数采用时域解调的方式。文章将离散短时傅立叶变换（DSTST）应用到对应答器2FSK信号的解调,并且提供出一种简单可行的同步方法．对系统的硬件电路进行设计,包括A／D转换模块、RAM模块、算法模块、地址调整模块、判决模块．     

基于软件无线电的2FSK相干解调

为检验软件无线电平台的优越性,提出基于软件无线电的采用相干解调法解调2FSK信号的方法.根据2FSK的调制解调原理,学习Matlab/Simulink软件中的模块,并利用模块搭建模型,对各模块的参数进行设计,在软件中仿真通过,并将模型通过协同仿真生成源代码下载到软件无线电平台上.相干解调法需要载波同步,从而使解调设备相对复杂.所设计的电路经过软件仿真的信号与发送信号一致,硬件验证协同仿真后的信号与发送信号一致,证明电路工作准确可靠,达到了预期效果.     

FSK制式来电显示的几种解码方式比较

主要探讨基于FSK制式的主叫号码来电显示的几种解码方式,详细介绍专用电路解调、锁相环解调和数字信号处理器(DSP)软件解调的识别方式,给出相应理论依据和实验数据,最后分析各种解码方式的优缺点.     

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.