基于Matlab的IIR数字滤波器设计方法比较及应用

滤波是信号处理的基础,滤波运算是信号处理中的基本运算,滤波器的设计也就相应成为数字信号处理的最基本问题之一。这里着重IIR数字滤波器的设计研究,应用Butterworth滤波器,ChebysheveⅠ型滤波器,ChebysheveⅡ型滤波器以及椭圆滤波器分别对低通、高通、带通和带阻四种滤波器形式进行比较仿真,通过不同设计方法的对比,将各种滤波器的设计特点很好地呈现出来。应用了Butterworth滤波器实现了混合信号频谱的分离,取得了良好的仿真效果。     

MAX262滤波器在地下金属管线探测仪中的应用

基于可程控的开关电容有源滤波器MAX262,设计一种切比雪夫型多频点带通滤波器.通过对系统时钟分频和自定义时钟,实现对其在地下金属管线探测仪中所有工作频率的覆盖,并结合其四阶传输函数和编程辅助软件,给出了各个频点的滤波器编程参数.实测结果表明,该多频点带通滤波器能有效处理不同频率的信号,且滤波效果令人满意.     

电流模式N阶CDBA-RC通用滤波器的系统设计

该文提出了利用电流差分缓冲放大器CDBA(the Current Differencing Buffered Amplifier)实现n阶电流模式滤波器的方法。基于信号流图给出了系统的设计公式,并举例设计了5阶Butterworth低通、高通及4阶Butterworth带通滤波器。PSPICE仿真表明,结果与理论分析完全吻合。该滤波器不仅电路结构简单,而且用的元件数目很少。     

基于MAX274的音频滤波器设计

介绍MAX274有源滤波器的特性及计算电路参数的原理和数学推导过程.并介绍了MAXIM公司专用滤波器设计芯片配套开发软件的使用方法.给出了简洁、有效的滤波器设计解决方法,设计了通带范围为300Hz～3400Hz的音频有源切比雪夫型带通滤波器.实际滤波效果良好.     

基于Delphi的IIR数字滤波器的设计与实现

滤波是数字信号处理的基础,数据采集过程中经常会引入高频干扰,文章利用巴特沃斯(Butterworth)滤波器设计方法,设计了一种IIR低通数字滤波器,并基于Delphi环境应用软件设计的方法实现了IIR滤波器。通过滤波,信号里面的干扰信号基本上被滤除,有用信号未受到影响,滤波效果尚可,具有一定的实用价值。     

基于MAX267的自适应带通滤波器的设计

叙述了用开关电容滤波器MAX267构成二阶自适应带通滤波器的设计.根据驱动信号的频率,运用锁相倍频原理为MAX267提供时钟信号,使其带通滤波中心频率将跟随特征信号频率变化,克服了传统滤波器带通中心频率不易改变的缺点,解决了大功率超声应用中基波信息的提取问题,为频率跟踪和功率控制提供了可靠的信息.实验结果表明,该滤波器较好地实现了自适应带通滤波的功能,能应用于大功率超声设备中.     

基于MAX274的音频滤波器设计

介绍了MAX274有源滤波器的特性及计算电路参数的原理和数学推导过程。说明了MAXIM公司专用滤波器设计芯片配套开发软件的使用方法。给出了简洁、有效的滤波器设计方法,设计了通带范围为300～3400Hz的音频有源切比雪夫型带通滤波器。实际滤波效果良好。     

MAX262滤波器在多通道声发射监测仪中的应用

为了实现多通道声发射监测仪中对从传感器接收到的声发射信号进行低通三档和高通三档的程控滤波,基于可程控开关电容有源滤波器MAX262,设计出了一种由低通滤波器和高通滤波器级联而成的切比雪夫型带通滤波器,并通过单片机控制两个时钟产生器DS1099的使能端,选择不同的时钟频率,实现了信号处理模块中所有截止频率的覆盖.结合MAXIM公司提供的滤波器编程辅助软件,给出了各个频点的滤波器编程参教及软件设计主程序流程图,为多频段可程控滤波器的设计提供了新的思路与方法.实测结果表明,该滤波器的滤波效果良好.     

基于MAX267的程控滤波器的实现

分析了双二阶开关电容有源带通滤波器MAX267的中心频率f0和品质因数Q,同时运用AD637真有效值转换,ADC0809模／数转换和单片机AT89C51对模拟信号进行处理。介绍了线性调频连续波（LFMCW）雷达系统中基于MAX267的程控滤波器的设计原理及流程,给出了具体电路及程序,并提供了在滤波频率从5～10kHz自适应四阶带通滤波器的应用实例。     

基于对数域无损积分器的高阶滤波器设计

提出利用双极型晶体管构成的对数域无损积分器以及对数压缩和指数扩展电路实现高阶滤波器.基于无源网络模拟,该设计不仅方法简单,而且使用元件种类很少,易于集成给出一个6阶Butterworth带通滤波器设计实例.PSpice仿真结果表明,该对数域滤波器能在低电压条件下工作,并具有高频、宽调谐范围和低失真等特性.     

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-