一种0.8GHz～6GHz CMOS超宽带低噪声放大器设计

给出了一个针对0.8GHz～6GHz 的超宽带低噪声放大器 UWB LNA(ultra-wideband low noiseamplifier)设计。设计采用0.18μm RF CMOS 工艺完成。在0.8GHz～6GHz 的频段内,放大器增益 S21达到了17.6dB～13.6dB。输入、输出均实现良好的阻抗匹配,S11、S22均低于-10dB。噪声系数(NF)为2.7dB～4.6dB。在1.8V 工作电压下放大器的直流功耗约为12mW。     

3GHz～5GHz超宽带噪声系数稳定的低噪声放大器

采用共源共栅级结构和源极负反馈电路设计了一款应用于超宽带系统的低噪声放大器电路。结合巴特沃斯滤波器的特性,实现放大器的输入、输出匹配网络,并详细分析了电路的噪声系数。基于TSMC 0.18μm CMOS工艺,在3 GHz～5 GHz频带范围内对电路进行ADS软件仿真。仿真结果表明,在1.8 V供电电压下,功耗为13.2 mW,最大增益达到15 dB且增益平坦,最大噪声系数仅为1.647 dB,输入反射系数S11<-10 dB,输出反射系数S22<-14 dB。     

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ADS的低噪声放大器设计

高性能的放大器对设计一个好的射频通信系统具有重要意义。本文分析了低噪声放大器设计的基本理论,并完成了一个中心频率为2.4GHz的低噪声放大器的设计。该设计选用了P-HEMT ATF54143器件.Agilent Advanced Design System（ADS）仿真结果表明该放大器的增益达到15 dB,噪声系数小于0.7 dB,输入输出驻波比均小于1.5,满足放大器预定的设计目标。     

DC到2.6GHz硅基MMIC放大器

本文采用基于硅基的：BiCMOS工艺设计制作了一款带宽为DC到2．6GHZ的低噪声、高增益MMIC放大器。该放大器为了实现从DC到2．6GHz的带宽，保证有足够的增益和理想的增益平坦度，采用了负反馈结构，两级级联，并选用了一种结构新颖的微波晶体管。该放大器具有功率增益高、频带较宽、噪声系数较小的特点。在仿真过程中其3dB带宽约3GHz，增益为26．6dB(1．5GHz时)，1dB压缩点输出功率约为1dBm；样品的实测结果为3dB带宽约2．6GHz，增益为26dB(1．5GHz时)，1dB压缩点输出功率约为1dBm。     

基于噪声消除技术的超宽带低噪声放大器设计

基于TSMC 0.18μm工艺研究3 GHz~5 GHz CMOS超宽带无线通信系统接收信号前端的低噪声放大器设计。采用单端转差分电路实现对低噪声放大器噪声消除的目的,利用串联电感作为负载提供宽带匹配。仿真结果表明,所设计的电路正向电压增益S21为17.8 dB~19.6 dB,输入、输出端口反射系数均小于-11 dB,噪声系数NF为2.02 dB~2.4 dB。在1.8 V供电电压下电路功耗为12.5 mW。     

3 GHz CMOS低噪声放大器的优化设计

基于0.18 μm CMOS工艺,采用共源共栅源极负反馈结构,设计了一种3 GHz低噪声放大器电路.从阻抗匹配及噪声优化的角度分析了电路的性能,提出了相应的优化设计方法.仿真结果表明,该放大器具有良好的性能指标,功率增益为23.4dB,反向传输系数为-25.9 dB,噪声系数为1.1 dB,1dB压缩点为-13.05 dBm.     

基于ADS的ku波段线性低噪声放大器的设计

主要介绍了宽带低噪声放大器的设计理论及用安捷伦公司的ADS仿真软件进行Ku波段（10.8~12.7 GHz）放大器的设计和仿真。在设计的过程中选择了Hittite Microwave公司的HMC564LC4芯片和安华高的AMMP-6408芯片,其噪声系数更低,增益和工作频率更高。使用微带线进行电路匹配,最终仿真结果：增益平坦度小于1 dB,增益大于30 dB,噪声系数小于2 dB。     

一种L波段宽带、平坦高增益低噪声放大器研究

为了实现放大器集宽带、平坦高增益、低噪声系数、且具有单电源控制等优异性能的统一,分析低噪放参数性能受器件选取、负反馈、匹配网络等方面的影响情况。采用AVAGO公司的ATF531P8和ATF35143晶体管,通过三级拓扑结构,介绍了一款L波段高性能放大器的实现过程。其工作频率覆盖1.3GHz~2.4GHz,相对带宽接近60%,远大于一般窄带放大器。带内增益大于34dB,增益平坦度仅±0.2dB,噪声系数小于1.2dB,最小仅0.6dB,端口驻波小于1.6:1。采用+5V单电源加电。     

宽带低噪声放大器的设计

探讨了使用S参数设计低噪声放大器(LNA)的方法。设计采用了PHEMT晶体管(ATF-35143)。设计过程首先从等效集总元件电路模型设计入手,然后对如何提高电路稳定性,降低噪声系数等方面进行了探讨,最后给出了工作带宽为1650M~2350M,增益G>29dB,增益平坦度GF±1dB,噪声系数NF<0.8dB的两级低噪声放大器的电路仿真结果。     

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.     

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.     

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     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

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。