基于功率合成器的20 GHz CMOS功率放大器设计

设计了一个工作频率高达20 GHz、最高输出功率23.4 dBm的CMOS功率放大器(PA),该PA由两级放大器组成,采用全差分Cascode电路结构。PA的输入、级间、输出匹配网络均采用片上变压器实现,实现单端输入、单端输出,功率合成器用来提高PA的输出信号摆幅。该PA基于TSMC 0.18μm CMOS工艺模型进行设计,采用Agilent ADS软件进行PA性能仿真和片上变压器的设计,版图仿真结果表明:在20 GHz频段内,PA的输入、输出完全匹配(S11=-13.85 dB、S22=-10.94 d B),小信号增益S21达到21.5 dB,芯片面积仅为0.56 mm~2。     

应用于移动手机的SOI线性射频功率放大器的设计

主要研究采用IBM公司SOI 0.18μm CMOS工艺设计应用于1.95 GHz WCDMA发射机的全集成线性功率放大器的设计方法。电路采用三级AB类放大器级联结构,模拟结果显示,在工作电压为2.5 V的情况下,CMOS射频功率放大器工作稳定,1 d B压缩点输出功率约为30 d Bm,增益约为28 d B,最大功率增加效率(PAE)约为42%。     

基于模拟预失真的2.4 GHz CMOS功率放大器设计

基于65 nm互补金属氧化物半导体(CMOS)工艺,设计一种2. 4 GHz的两级全差分功率放大器。通过采用片上变压器实现单端信号和差分信号之间的转换和输入输出阻抗匹配和将驱动级作为预失真器的模拟预失真技术提高线性度,从而实现高增益、高集成度和高线性度的功率放大器芯片。芯片面积为1. 08 mm×1. 37 mm。仿真结果表明:在2. 4 GHz的工作频点,功率放大器的-1 d B输出功率为22. 9 d Bm,功率附加效率为23. 5%,小信号增益为27. 2 d B,三阶交调失真为-35. 6 d Bc。     

基于GaN HEMT F类功率放大电路设计

本文基于一款商用GaN HEMT功率器件设计了一款工作在2.45GHz的高效F类功率放大器。该电路的设计利用负载牵引—源牵引仿真技术的方法,确定基波的最佳功率和最佳效率阻抗区域。输出匹配网络在功率器件电流源面对二次谐波短路,对三次谐波开路。另外,为该放大器设计了一款时序保护电路,可提供栅极电压-2.7V,漏极电压28V。仿真结果显示,在2.45GHz时,饱和输出功率为44.17dBm,功率附加效率为73.1%,增益14.1dB。可以应用于微波无线能量传输、微波加热等领域。     

E类射频功率放大器设计

基于0.18μm CMOS工艺,采用包含增益驱动级在内的两级电路结构,设计了一个工作频率为2.4GHz的E类开关模式功率放大器,并实现了全片集成.电路通过负载牵引技术获得最佳输出负载,在2V电源电压下经ADS2005A仿真,当输入信号功率为-10dBm时,获得约21.5dBm的输出功率,功率增益为31dB,功率附加效率达到57.69%的较好结果.     

一种高线性度的2.4 GHz CMOS功率放大器设计

为了满足目前物联网低成本、低功耗与较高线性度的市场应用需求,提出了一种高线性度的2.4 GHz功率放大器(PA)。该功率放大器为两级结构,为了提高增益的同时保持较低的静态功耗其驱动级采用了电流复用两级共源放大结构,并且使用了两级失真抵消的方法减小了晶体管跨导非线性的影响,同时采用二极管线性化偏置来补偿寄生电容非线性导致的增益压缩现象。该功率放大器采用0.18μm CMOS工艺,后仿真结果表明,在2.4 GHz工作频率下,该PA小信号增益为30 dB,输出1 dB压缩点为22 dBm,静态功耗为53 mW,功率附加效率峰值为31%。     

一种用于固态功率放大器的ALC电路

设计了一种用于X波段固态功放的ALC电路,根据输出信号功率控制可变衰减器的衰减量,对放大器的增益和输出功率进行调节。放大器工作频率范围为8.0 GHz～8.5 GHz。在室温条件下,当输入功率在-5 dBm～+5 dBm范围变化时,在ALC电路控制下放大器输出功率稳定在13.2 dBm～13.7 dBm之间,增益波动小于0.5 dB。     

基于SiGe HBT的38GHz功率放大器设计

功率放大器(Power Amplifier,PA)是射频前端关键的模块,基于0.13μm SiGe HBT工艺,设计了一款38 GHz功率放大器。提出了HBT集电极寄生电容和传输线谐振的方法减小芯片面积,针对毫米波频段下,晶体管可获得最大增益较低,采用堆叠晶体管提高了功率放大器的增益,同时通过优化有源器件参数,提高了功率放大器的输出功率和效率。仿真结果显示,在4 V的供电电压下,工作在38 GHz的功率放大器1 dB压缩点输出功率为17.8 d Bm,功率增益为19.0 dB,功率附加效率为32.3%,功耗为252 mW。     

一种12GHz的高增益低噪声放大器

通过分析GaAs pHEMT器件特性设计了一款两级高增益、低功耗的低噪声放大器.采用两级结构提高低噪声放大器的增益,设计了一种共用电流结构,降低了放大器的功耗,同时降低电路噪声.输入、输出匹配均采用LC阶梯匹配网络,具有良好的匹配性,并使用CAD软件对电路进行设计优化.电路仿真结果表明,在中心频率12 GHz下实现了增...     

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。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.