MAX038高频程控函数发生器设计

文章详细介绍了一种采用单片机对高频函数发生器MAX0 38芯片进行程序控制的函数发生器的设计方法 ,该发生器的输出有正弦波、三角波和方波信号三种波形 ,输出信号的频率在 0 .1Hz～ 2 0MHz范围内通过程控的方法进行调节 ,输出波形稳定 ,失真度也很小     

基于DSP+CPLD的高精度信号发生器

介绍了基于直接数字式频率合成(DDS)原理的全数字信号发生器(DSP),利用DSP芯片快速、高精度的运算优势以及CPLD芯片灵活的编程逻辑、大容量存储功能的特点,采用通用可编程芯片以及数字波形合成技术,形成高稳定、高精度、高动态的数字合成信号.该信号发生器可产生0～25 kHz的正弦波、三角波和方波,输出电压峰峰值为0～5 V,频率步进1 Hz,幅度步进0.001 V.     

基于AD9851的正弦信号发生器设计

基于直接数字频率合成(DDS)原理,采用AD9851型DDS器件设计一个正弦信号发生器.实现50 Hz～15 MHz范围内的正弦波输出,同时通过对器件的控制编程与相关的简单外部电路切换产生各种调制信号.通过自动增益控制(AGC)和功率放大,在50 Ω负载的情况下,该正弦信号发生器在100 Hz～10 MHz范围内输出稳定正弦波,电压峰峰值为0～5 V±0.3 V.     

正弦信号发生器的设计与实现

为精确地输出正弦波、调幅波、调频波、PSK,ASK等信号及保证信号的高可靠性,设计出一种新型的正弦信号发生器.该正弦信号发生器以可编程逻辑器件CPLD和单片机AT89S52为基础,采用数字频率合成DDS技术实现频率合成功能,结合高速D/A器件AD9713使得输出频率维持在1k～10MHz范围内,步进为100Hz,且通过对CPLD采用相应的数字控制算法实现调频FM,调幅AM和健控PSK,ASK数字调制功能.测试结果表明,设计的正弦信号发生器输出信号稳定度优于10~-4,在频率范围内50Ω的负载上输出正弦波电压幅度稳定在6±0.6V,波形无明显失真,系统的整体性能良好.     

基于AD9850的信号发生器的设计

直接数字合成(DDS)是一种重要的频率合成技术,具有分辨率高、频率变换快等优点,在雷达及通信等领域有着广泛的应用前景.系统采用AD9850(DDS)与AT89S52单片机相结合的方法,以AD9850为频率合成器,以单片机为进程控制和任务调度的核心,设计了一个信号发生器.实现了输出频率在10Hz～1MHz范围可调,输出信号频率稳定度优于10-3的正弦波、方波和三角波信号.正弦波信号的电压峰峰值Vopp能在0～5V范围内步进调节,步进间隔达到0.1V,所有输出信号无明显失真,且带负载能力强.     

基于MSP430和DDS的信号发生器设计

本设计是基于MSP430和DDS的信号发生器。系统采用MSP430单片机为控制核心,利用DDS产生正弦波,并通过按键来选择输出的波形以及调节频率和相位,频率调节范围为0~10000Hz,可在液晶屏上显示。系统主要由信号发生模块、显示模块和控制模块组成,可输出正弦波、方波、三角波、锯齿波等各种不同的波形。此设计可产生比较稳定的波形信号,方便移植到实际应用中。     

基于AD9850的多功能信号源设计

AD9850以芯片为多功能信号源频率合成核心,以单片机(89C52)为控制和数据处理核心,实现了正弦波、方波及AM、FM、ASK、FSK、PSK等调制波形的产生和输出。结合键盘和显示部分,实现了任意频率值的选择和显示,构成了一个完整实用的信号发生器。该信号发生器可在10 Hz～40 MHz范围内实现任意频率的输出,步进值和输出幅值可调。经过对系统的最终测试与实验数据分析表明,该系统具有稳定性好、精度高、且范围宽等优点。     

基于AD9851的多功能信号发生器设计

信号发生器在导航、通信、雷达等领域有着广泛的应用。文中给出了采用DDS技术,并以AD9851芯片为核心来设计一种结构简单、性能优良的多功能信号发生器的具体方法。该信号发生器是以STC516RD＋单片机为控制核心,能够产生正弦波和方波,输出频率范围为1Hz-20MHz,频率分辨率0．1Hz,可实现定频、扫频、2PSK、ASK和FSK,并具有步进值大约6dB的输出幅度调节功能。     

一种基于DDS的幅值可调信号发生器的设计

提出了一种基于DDS(Direct Digital Synthesize)AD9850的频率、相位、幅值均可调节的正弦信号发生器.该正弦信号发生器采用AT89S52单片机为控制器,D/A转换器TLC5615与乘法器AD534相结合,实现输出正弦信号幅值可控,采用AD811控制输出正弦信号电压幅值,产生50 Hz～3 kHz频段的正弦波,步进频率为50 Hz.该信号发生器可应用在交变磁场测量仪和试验仪器、工程设计的函数发生器中.     

基于AD9851信号发生器的设计

基于直接数字频率合成（DDS）原理,采用AD9851型DDS器件设计一个信号发生器,实现50Hz～60MHz范围内的正弦波输出。通过功率放大,在50Ω负载的情况下,该信号发生器在50Hz～10MHz范围内输出稳定正弦波,电压峰峰值为0—5V±0．3V。     

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.