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。     

一种10GHz高增益低噪声放大器设计

提出了一种带有输入匹配网络优化方法的窄带10GHzLNA电路。通过插入全新的输入匹配网络,不仅满足LNA低噪声的要求,同时更使增益有所提高。提出的LNA采用0．181μmSiGeBiCMOS工艺,工作频率为10GHz。结果表明,提出的窄带HBT10GHzLNA电路,在10GHz频段测试增益大于lldB,噪声3．6dB,功耗9mw,达到了较好的匹配效果,有较好的稳定性,满足了收发机对LNA的指标要求。     

CMOS有源反馈跨阻放大器

高性能接收端前置放大器的实现在光纤通信系统中起着至关重要的作用,前置放大器的性能指标,如,噪声、带宽、增益等,在很大程度上影响着光纤通信系统的性能。在分析了各种结构前置放大器性能的基础上,给出了一个基于CMOS工艺的、RGC结构的,应用于2.5Gbit/s光纤通信系统的低噪声跨阻放大器的实现方式。为了减小输入等效噪声电流和提高带宽,采用了有源反馈代替电阻反馈。采用SMIC的0.18μmCMOS工艺仿真结果表明该电路具有60.18dB的跨阻增益,2.13GHz的带宽,输入等效噪声电流为8.9pA/Hz,电路功耗仅为15.3mW。     

采用噪声抵消技术的高增益CMOS宽带LNA设计

设计了一种面向多频段应用的CMOS宽带低噪声放大器。采用噪声抵消技术以及局部负反馈结构,引入栅极电感补偿高频的增益损失,电路具有高增益、低噪声的特点,并且具有平坦的通带增益。设计采用UMC 0.18μm工艺,后仿真显示:在1.8 V供电电压下,LNA的直流功耗约为9.45 mW,电路的最大增益约为23 dB,3 dB频带范围为0.1 GHz¹.35 GHz,3 dB带宽内的噪声约为1.7 dB1.35 GHz,3 dB带宽内的噪声约为1.7 dB⁵ dB;在1 V供电电压下,电路依然能够保持较高的性能。     

0.5umCMOS新型电流反馈放大器的分析与设计

设计了一种CMOS电流反馈运算放大器,通过在输出端采用电阻反馈,增强带负载能力,利用MOS管实现串联电阻以消除补偿电容带来的低频零点,通过高输出阻抗镜像电流镜增大了电路的增益,并用共源共栅电流源为电路提供偏置电流以减小电源电压的变化对偏置电流影响.使用BSM3 0.5um CMOS工艺参数,PSPICE模拟结果获得了与增益关系不大的带宽,电路参数为:84.2dB增益,447MHz的单位增益带宽,62度的相位裕度,138dB共模抑制比以及在Ⅳ电源电压仅产生0.7mw的功耗.     

一种高线性度宽带可编程增益放大器

设计了一种应用于超宽带无线接收机的高线性度宽带可编程增益放大器(PGA),该PGA采用线性度增强型源简并结构的放大器加电阻衰减网络的结构,增益的调节分两步完成,PGA Core实现6dB增益调节步长,电阻衰减网络实现1dB增益调节步长,PGA Core电路采用线性度增强型源简并结构放大器,提高PGA的线性度。PGA采用SMIC 0.18μm混合信号CMOS工艺,1.8 V电源电压供电,仿真结果表明,该PGA增益范围-4~28dB,1dB步进,3dB带宽大于280 MHz,最大增益时输出三阶交调点(OIP3)25.7dBm,噪声系数(NF)22.24dB,总体电路消耗10.4 m A电流,芯片有效面积0.2 mm~2。     

带温度补偿和AGC功能的10Gb/s跨阻放大器设计

基于0.18μm BiCMOS工艺设计了一个工作速率为10Gb/s的跨阻放大器。为了解决温度变化对放大器性能的影响,引入了与温度变化有关联的电流(温度电流),从而锁存成与温度有关联的电压给跨阻放大器供电,使得放大器增益在频带内平坦和带宽变化减小。为了扩大输入信号的动态范围,引入了可变MOS电阻来实现AGC功能,使得放大器可以工作在较大的输入功率。为了提高增益,引入了两级差分放大电路,同时采用电容简并的方法来进一步扩展带宽。版图后仿真结果表明,跨阻放大器电路差分跨阻增益为9 kΩ,-3dB带宽为8.7GHz,等效输入电流噪声为17 pA/√Hz,灵敏度为-20 dBm,输入饱和光电流为2 mA,功耗为66 mW,电源噪声抑制比为-16 dB,放大器核心电路版图面积为94 mm×63 mm,整体版图面积为937 mm×828 mm,满足商业应用的要求。     

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。     

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。     

LM1875用于驱动精密直流伺服电机

一、电路结构与特点精密直流伺服电机驱动电路如附图所示。其中,放大电路采用同相放大器接法,反馈采用直流反馈形式。反馈电压从输出电压经电阻R1和R2分压取得,引至A反相端,与输入信号串接,故电路的放大倍数表示为R2/R1。由于单片功率运放LM1875的开环放大倍数高达90分贝,加之负载为电感性,很容易引起自激振荡。为此在电阻R2上并联电容C5,即进行超前补偿。同时,还配合采用C4去抑制因电机感性引起的寄生振荡。C2、C3则用于滤除电源噪声。     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate