TiWi—SL：2．4GHz WLAN解决方案

LS Research公司的TiWi—SL是高性能2．4GHz802．11bigWLAN模块,包括了必需的PHY,MAC和支持WLAN应用的网络层。模块和IEEE 802．11big兼容,WLAN发送功率＋19．0dBm或＋15dBm,WLAN灵敏度为．85dBm或．70dBm,工作电压2．9V-3．6V。主要用在HVAC控制、智能电网、传感器网络、医疗、家庭自动化和监测。     

OPNET Modeler下搭建IEEE802．15．3进程模型研究

分析IEEE802.15.3MAC协议下进程模型以及进程模型在实现IEEE802.15.3规范中的MAC接入机制。给出了的FSM图以及仿真结果。验证了IEEE802.15.3MAC协议对节点间的公平性。建立的IEEE802.15.3模型采用了标准的接口,能被直接移植到以后的相关研究模型中,对于后续的研究很有实用价值。     

一种适用于IEEE802．15．4（ZigBee）标准的2．4GHz CMOS射频收发机设计

本文提出了一种适用于IEEE 802．15．4标准的2.4GHz免认证ISM频段的全集成CMOS射频收发机．接收机采用低中频结构以降低功耗、提高灵敏度,发射机则采用直接上变频结构以降低设计复杂度和功耗．芯片采用0.18μm 1P4M CMOS工艺以及MIM电容制造,供电电压1.8V ．测试结果显示,在误包率为1％时,接收机灵敏度达到了-97dBm ,发射机输出至100Ω差分天线端口的最大输出功率为＋3dBm ．接收模式和发射模式下的电流功耗分别为17mA和19mA ,芯片面积3.3mm ×2.8mm ．     

基于2.4GHz的无线传感网络通信平台的设计

文章首先在平台的硬件架构上,采用了支持IEEE 802.15.4协议的CC2420芯片作为射频收发控制芯片,然后通过功率放大器来提高系统的发射功率和接收灵敏度,最后进行了实物平台测试,发射功率达到23dBm以上,平台通信距离达到2.2km以上,完全满足设计要求。     

全新2．4GHz射频高功率放大器

SST12CP21是2．4GHz 256-QAM射频高功率放大器，为256-QAM和IEEE 802．11n系统提供极低的EVM与电流消耗。其可在5V电压、MCS9 HT40MHz的带宽调制下1．75％的动态EVM提供高达23dBm的高线性输出功率，而电流消耗仅为320mA。此外，SST12CP21还可在3％EVM下为802．11g／n应用提供25dBm的线性输出功率，消耗电流仅为350mA。     

IEEE802．11网络VoIP容量估算方法

传统的IEEE802．11无线局域网环境下承栽VolP（Voice over IP）语音业务时,QoS和接入容量都严重受损,成为制约VoWLAN发展的瓶颈。文章以XG729编码的语音包在IEEE802．11b长PPDU模式传输的帧为例,通过分析VoIP包成帧效率、IEEE802．11b成帧效率和DCF协议效率,得到饱和条件下归一化系统吞吐率;同时计算出IEEE802．11a／b协议下VoIP语音理论传输容量,为进一步提升IEEE802．11无线局域网环境下语音传输能力研究提供基础。     

用于IEEE802．11b／g WLAN直接下变频接收机的射频前端设计

介绍了一种应用于IEEE802．11b／g无线局域网接收机射频前端的设计。基于直接下变频的系统架构。接收机集成了低噪声放大器、I／Q下变频器、去直流偏移滤波器、基带放大器和信道选择滤波器。电路采用TSMC0．18μm CMOS工艺设计,工作在2．4GHz ISM（工业、科学和医疗）频段,实现的低噪声放大器噪声系数为0．84dB,增益为16dB,S11低于-15dB,功耗为13mW;I／Q下变频器电压增益为2dB,输入1dB压缩点为-1 dBm,噪声系数为13dB,功耗低于10mw。整个接收机射频前端仿真得到的噪声系数为3．5dB,IIP3为-8dBm,IP2大于30dBm,电压增益为31dB,功耗为32mW。     

IEEE802．11g协议中一些问题的分析与研究

本文简要介绍了IEEE802．11协议族标准的发展过程，重点分析了IEEE802．11g协议标准。对IEEE802．11g协议中可能出现的一些问题进行分析和研究，并针对这些问题给出了相应的解决方法。     

IEEE802．11g协议关键技术及性能分析

一、IEEE 802.11g协议背景 自从1997年IEEE802.11标准制定以来,基于IEEE802.11的无线局域网标准发展迅速,已成为无线局域网的主要标准,广泛应用于办公、家庭、公共场所、学校和热点地区(如飞机场、码头仓库、超市)。IEEE802.11规定无线局域网工作在ISM频段,这一频段为免许可证波段。IEEE802.11是由大量的局域网以及计算机专家审定通过的标准,定义了一致的媒体接入层(MAC)和多样的物理层(PHY)。     

基于移动数字电视应用的宽带可变增益LNA设计

提出了0.13 μm CMOS工艺下可兼容多标准DVB-H/DAB/CMMB的移动数字电视调谐器射频前端双通道LNA设计。在UHF频段和L波段下,设计分别采用片上balun电路、双交叉耦合技术、开关转换电路、伪差分电路等技术以达到LNA宽带匹配、可变增益、低NF及高线性度的指标要求。版图后仿真结果显示:在UHF频段,仿真频率范围为470~860MHz,LNA增益范围为14.7~38.8dB,NF<2.4dB,IIP3=1.979dBm;在L波段,仿真频率范围为1.4~1.8 GHz,LNA增益范围为13~38.5 dB,NF<2.7 dB,IIP3=3.605 dBm。该设计较好地实现了多标准下LNA宽带可变增益性能。     

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.     

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.     

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.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-