一种简易微波VCO的设计*

描述了一种高性能简易微波VCO器件的设计和实验。该器件基于负阻原理设计,利用微波FET和变容二极管等分立元件制作,具有高性价比的特点。设计过程中利用ADS软件进行电路的匹配和优化,通过合适的外电路设计对变容二极管VCO的调频线性度进行改善,同时,降低了VCO的相位噪声。实际电路的测试结果表明,当该VCO的中心频率为4.3GHz时,其调谐范围大于200MHz,输出功率大于5.2dBm,相位噪声优于-112dBc/Hz@1MHz和-83dBc/Hz@100kHz。     

微波砷化镓超突变结电调管容压特性的研究及其在VCO的应用

本文叙述低-高-低n-GaAs多层有源层的扩散平面超突变结的容压特性及其控制,并给出容压特性与压控振荡器(VCO)频率特性的关系.在X波段FET VCO的应用获得大于1000MHz的线性电调带宽,在X波段体效应波导腔VCO的应用获得大于600MHz的线性电调带宽,最后评述X波段倍频程VCO的应用前景.     

具有数字化可编程中心频率的VCO

图1所示的电路为窄带电压控制振荡器(VCO),其数字化可编程中心频率比率大于2:1。利用这种中心频率比率(F_(HIGH)/F_(LOW))大于2:1的VCO,通过简单的二进制除法,就能得到任何输出频率。VCO具有极高的频谱纯度,当使用高性能ECL时,典型的性能可大于230MHz。并且几乎能够瞬时启动和瞬时停止振荡。     

数字可编程的VCO

图1的电路是一种窄频带的VCO(压控振荡器),它具有设定数字以决定中心频率的可编程功能,其中心频率比(高频/低频)大于2:1。若对VCO再二分频,就可获得多种的振荡频率。该VCO的工作频率可大于230MHz(采用ECL器件),所以该电路可为用户提供高速的选通和禁止功能。     

PLL调频立体声接收机制作

锁相环(PLL)电路PLL(锁相环)电路的基本组成如图1。压控振荡器(VCO)是一种用电压控制振荡频率的电路。假定基准振荡器的频率为100kHz,若要构成一个700MHz 的PLL 路,VCO 的输出需经过分频系数 N=700的分频器。也得到一个100kHz 的信号,若两者完全相同,比较器输出的 VCO 的控制电压不变,就能得到稳定的70MHz 的输出。由于某种原因使频率发生变化,经比较器和 LPF 输出的电压产生高低变化,对 VCO 的振荡频率起到补偿作用,使振荡稳定。若频率增高,加在 VCO 上的电     

基于LTCC技术的VCO研制

压控振荡器(VCO)在通信、雷达、测试仪器等领域中的应用非常广泛,但宽带调谐、小型化一直是VCO的设计瓶颈。文章描述了基于一种低温共烧陶瓷(LTCC)技术的微波振荡器的设计和制作,建立内埋式电感模型,并通过专用微波电路设计软件(AWR)对VCO电路进行分析,调整VCO匹配电路。测试结果表明,VCO输出频点为1.5～2.3GHz,输出相位噪声为-106dBc/Hz@100kHz,输出功率为13dBm。外形尺寸为6.9 mm×6.9 mm×1.2mm,远小于传统VCO体积,适应系统小型化的趋势。     

X波段微带集成FET的压控振荡器

本文叙述了一种利用FET振荡管和GaAs超突变结变容二极管构成的电压控制振荡器(VCO).通过合理的电抗补偿和阻抗匹配技术的应用,VCO在8GHz得到调谐带宽1200MHz,输出功率大于20mW.     

一种2.2～5.5G宽带低相位噪声LC VCO设计

论文基于BiCMOS工艺,采用了8个LC VCO并列的工作模式实现了2.2～5.5 GHz的带宽范围的LC VCO,每个LC VCO可以进行单独的调节.在LC VOC的核心电路中采用电阻代替电流镜方式以及在输出处增加了两个三极管限幅,以得到较低的相位噪声.在各个LC VCO的中心频率处其相位噪声优于-96 dBc@100 kHz.当电源电压为5 V时,各个LC VCO的工作电流为3.2 mA～4.2 mA.     

单片集成的高频宽带LC VCO设计

设计了一款1.9~4.3 GHz的单片集成宽带VCO。采用三个低相位噪声LC VCO在频率上互相重叠的架构实现高频宽带特性,VCO内部集成中间抽头的差分电感。电路制造采用0.35μm SiGe BiCMOS工艺技术,VCO的工作频率达1.9~4.3 GHz,单元功耗仅为4 mA。在工作频率为2.46 GHz处,经过÷2分频器输出的相位噪声实测值为-97 dBc/Hz(100 kHz频偏下)。     

变容管压控振荡器

本文介绍了一种主为容管压控振荡器,利用对变容管C－V曲线的修正,使得VCO的线性度有较大改善,VCO输出频率为14．5－15．5GHz,输出率大于40mW,线性度优于1．1：1。     

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.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.