一种新型负反馈超宽带低噪声放大器的设计与实现

随着超宽带技术的发展,系统设计对低噪声放大器的性能提出了越来越高的要求。针对宽带放大器增益平坦度低。匹配性差等问题,本文从负反馈理论着手,改进了负反馈网络。通过ADS软件的辅助设计,实现了30MH—1．35GHz频段下的低噪声放大器的设计。通过对各项电路参数的优化,实现了增益为17．7dB,增益平坦度小于dB,输入输出电压驻波比小于1．5,噪声系数小于2．6的技术指标。     

基于ADS的低噪音放大器的仿真设计

通过分析低噪声放大器的性能指标要求,设计工具应用NEC公司的开发平台ADS Design Kit for NEC Electronics,设计单级及两级级联的低噪放大器,并对其进行优化。经模拟仿真,发现两者都能满足设计要求,而两级级联的低噪声放大器性能更优,其在2.1G到2.4G的频段上,增益达到了20dB,噪声系数小于0.5dB,稳定系数为4.399,输入输出驻波比小于-10dB。     

3～5GHz超宽带可变增益CMOS低噪声放大器的设计

基于TSMC 0.18μm RF CMOS工艺,设计了一款工作在3 GHz～5 GHz的增益连续可调CMOS低噪声放大器。采用RC电阻负反馈式结构以获得良好的输入匹配和噪声性能。通过改变第二级MOS管的偏流,在工作频段内获得了36.5 dB的连续增益可调。     

应用于北斗卫星通信系统的低噪声放大器设计

北斗卫星导航系统由我国自主研发,其研制目的是为了在日益严峻的世界环境下巩固我国的军事实力。北斗射频接收芯片是北斗卫星导航系统中整个地面端设备的核心,因此,关于射频接收机芯片的研发工作具有十分重要且实际的意义。文中在基于窄带低噪声放大器理论的基础上,采用TSMC0．18μmCMOS工艺设计了一种应用于北斗通信系统中的低噪声放大器。放大器采用改进的单转双电路结构,并通过缓冲级电路对差分信号的幅度和相位偏差进行了有效的校正。实验结果表明该电路在2．45GHz-2．55GHz频带内输入回波损耗小于-28dB,噪声系数小于1．1dB,功率增益大于15dB,电压增益高于32dB。     

低温L波段低噪声放大器设计调试方法

低噪声放大器是微波通讯系统中非常重要的功能器件.本文研究了使用在高温超导滤波器后级的低温低噪声放大器的设计和调试方法.总结了综合功率匹配,驻波匹配和噪声匹配的设计思路.同时针时低温下(70K)由于晶体管S参数的变化导致放大器性能和常温相比有很大改变的情况.利用Smith圆图和可调微带电容帮助调试.并研制了频带为1.9GHz-2GHz的低温低噪声放大器.其增益大于18dB,输入输出反射损耗小于-20dB,噪声低于0.5dB.     

基于切比雪夫网络修正的噪声优化超宽带LNA设计

基于TSMC 0.18μm CMOS工艺的研究,设计了一个应用于3~10 GHz超宽带无线通信系统接收前端的低噪声放大器。以经典的共源共栅的结构作为放大主架构,结合切比雪夫滤波器,实现超宽带输入匹配,并采用噪声消除技术优化LNA噪声性能。电路结构具有工作带宽大、输入匹配简单并且噪声性能优异的优点。仿真结果表明:在3~10 GHz频段内,S11和S22均小于-10 d B,S21为15 d B~10 d B,噪声系数NF为1.5 d B~2.3 d B,在1.8 V供电电压下电路功耗为14.5 m W。     

采用新型电流舵结构的增益可调UWBLNA

基于TSMC 0.18μm CMOS工艺,设计了一款工作在3 GHz⁵ GHz频段的增益可调超宽带低噪声放大器(LNA)。LNA输入级采用局部反馈的共栅结构,实现了超宽带输入匹配和良好的噪声性能;放大电路级采用提出的新型电流舵结构,实现了放大器增益连续可调;输出级采用源极跟随器,获得了良好的输出匹配。利用ADS2009进行仿真验证,结果表明,在3 GHz5 GHz频段的增益可调超宽带低噪声放大器(LNA)。LNA输入级采用局部反馈的共栅结构,实现了超宽带输入匹配和良好的噪声性能;放大电路级采用提出的新型电流舵结构,实现了放大器增益连续可调;输出级采用源极跟随器,获得了良好的输出匹配。利用ADS2009进行仿真验证,结果表明,在3 GHz⁵ GHz工作频段内,LNA获得了25 dB的增益可调范围,最高增益达到24 dB,输入端口反射系数小于-11 dB,输出端口反射系数小于-14 dB,最小噪声系数为2.3 dB,三阶交调点(IIP3)为4 dBm,在1.2 V电压下,电路功耗仅为8.8 mW。     

基于功耗限制的CMOS低噪声放大器最优化设计

分析了进行功耗限制条件下怎样得到低噪声放大器的最优噪声,并就阻抗匹配及小信号电压增益进行了详细讨论。介绍了采用0.25μmCMOS工艺设计的工作在2.4GHz频率下的全集成低噪声放大器。模拟结果表明,在2.4GHz工作频率下,低噪声放大器的功耗为16mW,正向增益S21可达15dB,反射参数S11、S22分别小于-23dB和-20dB,噪声系数NF为2.7dB,三阶互调点ⅡP3为-0.5dB。     

一种L波段低噪声放大器的设计与仿真

研究射频电路前端的天线信号放大和抑制噪声,进行了加快低噪声放大器的设计,提出了一种利用史密斯圆图和ADS软件快速设计和仿真LNA的方法.设计时输入端采用最佳噪声匹配,以获得较小的噪声系数;输出端采用输出共扼匹配,以获得较高的功率增益和较好的输出驻波比.通过对一个L波段低噪声放大器的噪声系数、功率增益、输入输出驻波比等参数进行仿真,结果验证了上述的方法.经反复调整后放大器在L波段内噪声系数小于1dB,增益达30dB,输出驻波比小于1.5,满足了设计要求,对从事LNA的设计来说有着重要的参考价值.     

一种卫星导航接收机低噪放的设计与实现

介绍了一种工作在1.1GHz～1.6GHz的多模卫星导航接收机低噪声放大器的设计与实现.为使低噪声放大器在较宽频带内的增益平坦度达标,采用的是源极串联负反馈方式.对低噪声放大器进行了设计和仿真,确定了其能够稳定工作、并且噪声特性和增益满足要求的电路形式.对实际电路的调试、测试结果证明了设计的正确性.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.