一种高性能的CMOS四象限模拟乘法器

本文介绍了一种带预处理电路的ＣＭＯＳ四象限模拟乘法器，对其预处理电路（有源衰减器及电平位移电路）和乘法器核心电路的非线性误差作了详细的讨论．设计采用３微米Ｎ阱硅栅ＣＭＯＳ工艺，并给出了电路的ＳＰＩＣＥ模拟结果．当电源电压为±５Ｖ时，功耗小于６．５ｍＷ，线性输入电压范围约为±４Ｖ；当输入电压范围限于±３Ｖ内时，总谐波失真和非线性误差均小于０．３３％，－３ｄＢ带宽为１３．０ＭＨｚ和２．２ＭＨｚ；当输入电压范围限于±２Ｖ内时，总谐波失真小于０．１８％，具有良好的性能．     

真空开关多次重燃的模拟

本文介绍了真空开关合闸时电极触头弹跳所引起的多次重燃现象的模拟研究。用“Ｍａｙｅｒ”型电弧方程式模拟多次重燃的电流和电压，模拟结果与实验结果相吻合。     

适于半导体器件模拟的改进Gummel算法

本文采用Ｓｌｏｔｂｏｏｍ变量把半导体器件模型归一化为奇异摄动问题．然后对该模型提出一种适于ｍ维（１≤ｍ≤３）数值计算的Ｇｕｍｍｅｌ算法，当外加偏压或器件测度（二维时如有效沟道长度，三维时如器件的有效体积等）足够小时，该算法是收敛的．数值例子表明，改进的Ｇｕｍｍｅｌ算法编程方便，收敛速度快．     

一种基于亚阈值区特性的CMOS四象限模拟乘法器

讨论了基于ＭＯＳ晶体管亚阈值区特性的ＣＭＯＳ四象限模拟乘法器的设计。分析了四种乘法器核的直流传输特性，给出的ＰＳＰＩＣＥ模拟结果验证了理论分析。模拟结果表明，对于电源电压为１．５Ｖ（或±１．５Ｖ），当输入电压范围限于±０．０８Ｖ时，非线性误差小于１％；－３ｄＢ带宽约为３４０ｋＨｚ，静态功耗小于１μＷ。给出的乘法器核可应用在便携式电子系统模拟信号处理电路中，特别适于在神经网络系统中的应用。     

电视机的抗干扰设计

简要介绍了干扰的理论，分析了模拟电视机内部干扰的主要特性，提出了设计时行之有效的解决方法，产简介了两个设计事例。     

模拟分量录像机AU—65E的维修

［例1］机型：AU-65E故障现象：重放磁带上信号时，在监视器上观察发现其图像上部杂波较大或不稳定。分析：图像上部信号不好，首先怀疑是磁迹跟踪不好，但调整录像机前面板上的磁迹跟踪电位器，发现并不能改善图像。于是判断是磁鼓入口侧的磁带运行异常，而引起的故障。检修：首先将录像机置于重放状态，用张力表（已校准）测量导柱PI和PZ之间的张力，为259，在正常范围内。然后，将示波器接至录像机调制／解调（W3）板的TP3OI，观察重放时其亮度磁头输出的YRF信号，很明显RF包络显示入口处的磁带通路不好，此时对导柱PI、PZ、P4…     

为数字世界提供高速模拟解决方案

在目前强调高速数字信号处理的领域中，大家可能会认为模拟线路已经成为过去。其实并不然，相反的，当数字化世界越来越蓬勃发展时，我们对更高性能模拟集成线路的需求反而越来越高。事实上在我们每天所接触到东西里面，许多被认为是数字化的产品当中包含了大量的模拟线路，如ADSL Modem，电脑，CD/DVD播放机，移动电话以及数字相机等。虽然这些都是相当高性能的数字化产品，但其中却包含了相当多的模拟处理电路。     

激光热处理的模拟及其应用

采用无量钢参数，导出了匀强矩形激光光斑相变硬化处理钢铁材料时表面以下各部分材料所经历的最高温度与其距表面距离的关系曲线族。仅由此曲线族，即可根据要求的淬火层深度以及单位时间处理的表面积，计算确定激光热处理的参数。     

坐磁悬浮列车,玩转磁悬浮LP模拟唱机Amari LP-100磁悬浮式唱机登场

上海龙阳路到浦东机场有一条磁悬浮列车，是世界上第一条商业用磁悬浮列车。有一次出差，去浦东机场时我特地选择体验了一回，果然不一样。虽然仅15分钟的路程。但以时速350公里以上的速度行驶时够刺激并且相当地平稳，与平时坐的铁轨列车感受完全不同。由于磁性作用，行驶时列车被悬空浮了起来，在启动和靠站时有略微的上升和下浮感觉。     

混合模式设计与深亚微米面临的挑战

１引言在２１世纪信息化时代的今天，人们已进入了数字时代。计算机内部核心以０与１格式的运算速度伴随着半导体技术的进步，现已达到每秒千兆位以上。相比之下，相对于数字的模拟技术，甚至会有“模拟技术迟早会被数字技术取代”的认识，这和模拟技术实际的发展存在很大距离。事实上，在全球以CPU、DRAM为主的半导体产业一度陷入低谷时，模拟器件产业却表现出稳健增长的态势。自１９９９年起保持以每年１９．１％的增长率上扬，市场规模逐年增加。尤其近年来随着信息家电、手机、PDA、网络、LCD显示器等新兴信息产品市场的兴起，为…     

Generative probabilistic models for multimedia retrieval: query generation against document generation

This paper presents the use of generative probabilistic models for multimedia retrieval. Gaussian mixture models are estimated to describe the visual content of images (or video) and are explored in different ways of using them for retrieval. So-called query generation (how likely is the query given the document model) and document generation (how likely is the document given the query model) approaches are considered and how both fit in a common probabilistic framework is explained. Query generation is shown to be theoretically superior, and confirmed experimentally on the Trecvid search task. However, it is found that in some cases a document generation approach gives better results. Especially in the cases where queries are narrow and visual results are combined with textual results, the document generation approach seems to be better at setting a visual context than the query generation variant.     

Least-squares moment matching reduction methods

It is shown how the two apparently different approaches to modelling reduction by least-squares time moment matching give identical results. This property also enables a clear understanding of how the method actually approximates the system. Computational savings are seen to be made by adopting the two-stage approach     

高速PCB 信号完整性仿真与分析

针对如何能缩短电路设计开发流程和提高设计人员工作效率,本文主要提出了如何有效解决信号完整性问题。 介绍了一种信号完整性分析的方法,使用IBIS 模型进行信号完整性分析,通过加载芯片的IBIS 模型对高速PCB 板进行 仿真,并对仿真结果进行优化分析,达到验证设计的目的。     

InGaAs/InP DHBT technology and design methodology for over 40 Gb/soptical communication circuits

High-performance technologies and adequate design methodologies are required to address the needs of very high-speed ICs (VHSICs) for over 40 Gb/s optical communications. We describe improvements we have introduced in our InP DHBT technology, and how our design methodology has evolved, we show how it results in improved circuit designs, and present some recent results, with some considerations on measurement limitations     

The brits are calling

This paper discusses the results of a comprehensive annual report prepared by the UK regulator, Ofcom, that examined how consumers are using electronic communications and media technology in Britain in 2006, and how these consumption patterns are shaping the next generation of services     

Stability of multivariable control systems designed using reduced-order models: further results

Further new results regarding stability of the original model designed using reduced-order models are derived. The new stability conditions given are independent of how the reduced-order models are obtained, and the results could be adapted to any general multivariable frequency design methods.     

Parametric Characteristic Analysis for Generalized Frequency Response Functions of Nonlinear Systems

In order to explicitly reveal the relationship between system frequency response functions and model parameters which define system nonlinearities, and consequently unveil a direct connection from model parameters to system frequency response characteristics, a parametric characteristic analysis approach is proposed for Volterra systems described by a nonlinear differential equation (NDE). The parametric characteristics of the generalized frequency response functions (GFRFs) for the NDE model are established, and some important properties are discussed, which can explicitly reveal what model parameters contribute and how these parameters affect the GFRFs. Based on the parametric characteristic analysis, it is demonstrated how the system frequency domain characteristics are related to the system time domain model parameters and how the output frequency response function can now be determined explicitly with a detailed polynomial structure. These new results provide a significant and novel insight into the analysis and design of nonlinear systems in the frequency domain. Several examples are included to illustrate the results.     

The general sources of noise in vacuum tubes

This paper discusses the genesis of noise in vacuum tubes. Simple if not rigorous derivations for various kinds of noise are given, and it is shown how the noise on an electron beam can be characterized. A few simple examples show how particular results can be obtained but nothing involving laborious mathematics is included. The effect of transverse velocities is discussed briefly, but no results are given.     

英语基本名词短语识别技术研究

基本名词短语识别是自然语言处理领域的非常重要的子任务。文中总结了英语名词短语识别的一些代表性的方法并对识别结果进行了比较和对照，介绍了识别名词短语所需的知识、结果的表示和评价标准；最后指出了目前名词短语识别的发展趋势。该研究对相关领域研究起到借鉴作用。     

Scan-plane reduction techniques for planar near-field antenna measurements

In this work, two planar near-field scan-plane reduction techniques are considered and results are presented. It is shown how truncation based on field-intensity contours, instead of simple geometric truncation, can in some cases improve the efficiency of the truncation process. Both techniques are applied to measured data sets, and it is shown how these methods can be used to reduce data-acquisition times, while also assessing the impact of the total acquisition surface reduction on the far-field radiation-pattern integrity.