超低功耗DDS芯片-AD9952及应用

介绍了AD公司最新的DDS芯片-AD9952的基本原理和主要性能,提出了由AD9952为主,构成宽频带、低相噪频率源的方案,使用CPLD作为控制电路。对如何提高DDS输出频谱纯度进行了探讨,并给出电路解决方案。     

基于DDS的跳频通信信号源的研制

首先介绍了DDS(直接数字频率合成器)的结构和工作原理,然后给出了一个基于AD公司的DDS芯片AD9952和TI公司的DSP芯片TMS320VC5402的跳频通信用信号源的方案,分析了部分组成.最后,给出了按该方案设计的频率范围为46 MHz～136 MHz的跳频信号源的测试结果和设计中的注意事项.测试结果表明,该方案满足设计要求.     

基于DDS的高精度信号发生器设计

DDS因具有较高的频率分辨率、较快的变频速度、变频相位连续、相噪较低、易于功能扩展和全数字化、便于集成等优点,在通信、雷达、遥控等许多电子领域显示出广泛的应用前景。文中介绍了DDS技术的基本原理及其芯片的工作原理、性能和利用AD9952设计出高稳定度的发生器,其频率稳定度可以达到10-10～10-11/s。     

DDS芯片及其在雷达回波生成系统中的应用

概述了DDS技术的一般原理，详细介绍了由美国AD公司生产的高性能完全正交DDS芯片AD9854的结构、性能及工作原理。最后给出了一个使用该芯片实现雷达回波信号生成系统的应用实例。     

高性能DDS芯片AD9854结构功能简介

本文介绍了ADI公司的高性能DDS芯片AD9854。AD9854是一款CMOS工艺的300MSPS正交完整DDS芯片,在现代波形发生与合成、通信领域有着广泛的应用。本文介绍了DDS技术的基本原理及AD9854内部结构级功能。     

ADI推出业界第一款多通道DDS器件轻松应对同步设计的挑战

美国模拟器件公司(A N A L O GDEVICES,INC.),近日发布业界唯一的多通道直接数字频率合成器(DDS)器件,从而为系统工程师在多种应用中面临的两种普遍存在的设计问题提供了解决方案。ADI公司新的DDS允许对多达4个内部同步输出通道独立编程,其中4通道AD9959和2通道AD9958能够对多通道信号之间的不平衡提供有效的校正控制,从而能使系统工程师用相当少的时间和精力去处理这个通常很复杂的系统设计部分。对于印制电路板(P C B)面积受限制的应用系统,AD9958和AD9959由于多个DDS通道集成在一颗芯片上简化了设计过程,而无需几颗单通…     

AD9851与AT89C51在信号源中的应用

本文介绍了美国模拟器件公司采用先进DDS直接数字频率合成技术生产的高集成度产品AD9851芯片的引脚功能、特性和工作原理，同时介绍了单片机芯片AT89C51的特性及这两个芯片在信号源中的应用。     

基于CPLD控制的声信号发射系统设计

介绍了一种声信号发射系统的设计方案,系统是基于CPLD产品XC2C128控制,并通过EPROM（M27C64A）实现了波形存储,信号经D／A转换器（AD5330）、功率放大器（MAX9703）和变压器输出。另外,可通过改变存储器内波形存储的编码方式或存储器的型号和容量。实现时分复用（TDM）、频分复用（FDM）和码分复用（CDM）。经多次实验验证了该系统的可行性和扩展性。     

基于CPLD控制的声信号发射系统设计

介绍了一种声信号发射系统的设计方案.系统是基于CPLD产品XC2C128控制,并通过EPROM(M27C64A)实现了波形存储,信号经D/A转换器(AD5330)、功率放大器(MAX9703)和变压器输出.另外,可通过改变存储器内波形存储的编码方式或存储器的型号和容量,实现时分复用(TDM)、频分复用(FDM)和码分复用(CDM).经多次实验验证了该系统的可行性和扩展性.     

DDS调制芯片AD7008的原理及应用

基于DDS(直接数字频率合成)专用芯片得到广泛应用,使得信号的产生与调制变得更为简单。介绍了DDS芯片AD7008的内部结构与工作原理,分析了采用AD7008实现正弦信号发生器、调幅、调频的方法,给出了基于89C51单片机与AD7008的软硬件设计方案。     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.