一种高性能的功放控制器设计

CMOS控制器是射频功放模组的重要单元,它为射频功放提供稳定的偏置点和简单的逻辑控制。采用复用误差放大器和补偿电容的结构,设计出一种高性能的应用于WCDMA手机功放模组的功放控制器。电路采用TSMC 0.25μm标准CMOS工艺实现,芯片尺寸为840μm×440μm。模式切换时间小于1.5μs,1 GHz下的PSRR小于-10 d B。测试结果表明:输出电压均值为2.894 V,标准差为17 m V,温度系数为-370 ppm/℃,良率为94%。     

基于Multisim的功率放大电路仿真分析

采用Multisim软件仿真的方法,对乙类互补对称放大电路进行仿真分析,通过分析电路负载的输出波形观察功放中容易出现的交越失真,在两个三极管的基极串联了两个二极管后,提供了偏置电压把静态工作点设置得比截止点稍微高一些,使放大器工作在甲乙类放大状态,有效消除了交越失真。经过仿真和分析表明,乙类功率放大器是实现功放小型化、高效率、高功放的重要途径。     

收发机系统的制作

本文介绍了直接调频、高频功率放大器、小信号调谐放大器、TA7176斜率鉴频器所组成的收发系统结构,其接收距离大于2米。其中直接调频采用了变容二极管直接调频,高频功放采用8050作为功放管、基极零偏置、集电极并联偏置,小信号调谐放大采用了9018作为放大管、两级放大,TA7176作为中频鉴频器。     

欲穷千里目更上一层楼：介绍隆宇第六代功放模块电路及其它

我们去年在准乙类动态同步偏置功放模块电路基础上成功地运用了功放全信息反馈系统新技术,解决了传统功放固有的频响内阻难题(我们喻为水盆壁效应),令频响延伸到1MHz以上,还有0.7～1V输出幅度,得到意外的三维立体声场效果,我们将此命名为第五代模块。但与胆机比较,觉得低音速度快了些,下沉度虽好,但没有完全达到胆机低频那种绵软的弹性,这在崇尚胆味风格的顶级发烧友圈内还不能完全认同。现在我们又成功地研制出柔性动态反馈偏     

C波段高效率内匹配功率放大器设计

阐述了一款内匹配功率放大器的设计过程和测试结果。该放大器工作在5～5.8 GHz,采用氮化镓HEMT工艺,在28 V漏极供电电压下实现了48 dBm输出功率和55%功率附加效率。同时,该内匹配放大器将栅极和漏极偏置电路设计在芯片内部,无需在外部设计偏置电路,在保证功放性能的同时实现了小型化。该设计充分体现了GaN内匹配电路的高功率、高效率、小型化的优势。     

动态偏置射频宽带功放设计

射频宽带功率放大器是目前功率放大器的主要发展趋势。为了提高射频宽带功率放大器的增益平坦度与效率,采用推挽结构LDmos晶体管,使用ADS软件对动态偏置电路和匹配电路进行仿真设计。详细介绍了动态偏置功率放大器的工作原理及其实现方法。实现了多倍频程带宽、确保带内增益平坦、提高功率附加效率。仿真结果表明该功率放大器对于100MHz~400MHz的信号,在整个输入功率变化范围内,功率附加效率（PAE）与传统的功放相比提高了5~15%左右。     

基于C8051F的功放监测与显示系统设计

针对导航定位系统对功率放大器连续长时间工作的要求,提出了功率放大器监控与显示系统应具备的控制、检测和显示功能,以C8051F系列单片机作为主控器,设计了功率放大器的监测与显示系统.给出了系统硬件原理框图,阐述了系统软件的组成、相关程序流程、菜单式显示拓扑结构以及冗余系统主/备功放切换控制原理,实现了功放的本地与远程控制、功放工作状态和实时参数的中文菜单式显示以及功放的冗余切换功能,保证了功放在导航定位系统中长期不间断地可靠工作.     

基于AVR单片机的功放控保电路设计

针对引起功放失效的几种主要原因,提出并设计了一种基于单片机的功放控制保护电路。介绍了控制保护电路的组成和工作原理,确定了功放状态检测电路的形式。利用AVR单片机ATmega8和相应检测电路实现对功放的监测,并达到过压、过流、过温和过载保护的目的,同时给出了相应的电路原理图和主程序流程,并对设计中需要注意的问题进行了说明,总结了关键技术,最终对性能测试结果进行了分析。     

一种应用于LTE-A的双功率模式宽带功率放大器设计

针对LTE-A移动终端应用,采用双功率模式架构设计了一款宽带功率放大器,利用功放工作模式的切换,改善了功放回退区域的效率。该功放还采用了InGaP/GaAs HBT和AlGaAs/InGaAs pHEMT的一体化工艺,将功放电路与控制电路单片集成,实现模式控制的片上切换,能有效提高功放的集成度。该功放在工作电压为3.4 V,频率2.3~2.69 GHz范围内,使用10 MHz LTE调制信号输入,在输出功率为10 dBm时,测得LPM相对于HPM效率提高至少6%,有效提高了功放功率回退时的效率,功放的性能在全频带内满足3GPP协议要求。     

数控D类功放系统的设计与分析

介绍了一款基于DDX功率驱动技术、既具有USB数字音频接口又具有模拟音频接口的数控D类功放系统。采用AT89C2051作为主控芯片,通过事件扫描方式让控制更有效率,通过I2 C总线让TDA7449芯片具有16阶的音量控制、16阶的音调控制、声道选择、静音控制等功能;利用数学模型,分析了该数控D类功放具有高效率和很好的音调控制功能;通过LC二阶滤波电路的分析和设计,让功放的最大总谐波失真控制在0.5%以内。     

高灵敏度小型化红外光声气体传感系统

研制了一种高灵敏度小型化红外光声气体传感系统.该系统检测灵敏度高,对乙烯气体体积分数的检测限达到20×10-9以下.对光声信号和检测相位之间的关系进行了详细的研究,分析了光声信号中峰值相位变化的因素.结果表明:在固定相位延迟下利用锁相放大器检测光声信号可以获得比较高的灵敏度.同时根据对光声信号和相位延迟关系的研究,提出...     

嵌入基于案例记忆机制的个人辅助Agent

个人辅助agent是一种能够帮助用户解决工作环境中特定任务的认知agent。为个人辅助;agent设计了一种记忆机制,用于表示和组织个人辅助agent的记忆。受基于案例推理思想的启发,构建了一个记忆处理器,以对记忆进行更新和管理。在多agent平台—OMAS中实现了个人辅助agent原型系统。实验表明,具有记忆机制的个人辅助agent能更有效地执行用户任务。     

基于RBF神经网络的射频功放行为模型研究

为了设计和优化高线性功率放大器和通信子系统,在系统级仿真中,构建功率放大器精确的行为模型是极为重要的。应用实际功率放大器晶体管测试板,通过ADS（Advanced Design System）仿真得到大量功放输入输出数据,建立了一个基于RBF（Radial Basis Function）神经网络的行为模型,给出了RBF 神经网络的结构设计及K-均值聚类算法和共轭梯度优化算法,并进行了模型检验。结果表明,基于RBF神经网络的功放行为模型具有较高的精度,相对于BP 神经网络模型具有更高的逼近能力和速度。     

Does peer assessment in on-line learning environments work? A systematic review of the literature

There is an increase use of Peer Assessment (PA) approaches in On-line Learning Environments to support students and teachers on educational process. However, the community still lacks a comprehensive understanding of how Peer Assessment behaves within these educational environments, since there are no studies that make an analysis of the researches which has been conducted in this context, analysing the benefits and disadvantages of the use of Peer Assessment. Thus, the main goal of this work is to investigate and better understand how PA contributes in student learning as well as can bring benefits to the teachers involved. In order to meet our goal, we conducted a systematic literature review (SLR). In summary, the main findings are: (1) there are empirical evidences of the benefits of using PA in both industry and academy, and in several educational levels; (2) PA is most addressed to the correction of written activities on on-line courses; (3) About 60% of the articles showed PA improvement in student performance; (4) About 1/3 of the studies showed PA brings some benefits to teachers; (5) In some studies the use of the PA had difficulties, especially issues related to student motivation, which impairs the peer review process.     

Behavioral modeling for concurrent dual‐band power amplifiers using 2D hammerstein/wiener models

Behavioral modeling for the concurrent dual‐band power amplifier (PA) is a critical problem in practical applications. The nonlinear distortion in the concurrent dual‐band PA is quite different from that in the conventional single‐band PA. This article analyzes the nonlinearities in the concurrent dual‐band PA and reveals that both input signals in the dual bands are important for the behavioral modeling. The 2D Hammerstein model and 2D Wiener model are proposed for the first time for the concurrent dual‐band PA. They are extended versions of conventional Hammerstein and Wiener structures used in the single‐band PA by including the cross‐band intermodulation in the static nonlinearity block. The proposed 2D models require much less coefficients than the original work of the 2D‐DPD model. Experiments were carried out for an 880 MHz/1960 MHz concurrent dual‐band Doherty PA to demonstrate the effectiveness of the proposed models. The results clearly show that less than ?40 dB normalized mean square errors (NMSEs) are obtained in the dual bands in the behavioral modeling. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 646–654, 2013.     

Analysis and improvement of PSRR in an envelope‐tracking power amplifier using a common‐drain amplifier topology

A common‐drain power amplifier (PA) for envelope tracking systems is presented. In envelope tracking, the main PA operates mostly in compression and the power supply rejection ratio (PSRR) is not high. Furthermore, the output noise of the supply modulator can be mixed with the RF signal and generates out‐of‐band emissions. In this article, instead of using a common‐source topology, the PSRR of the envelope tracking PA is inherently improved by utilizing a common‐drain topology. A comprehensive analysis shows that the common‐drain topology is less sensitive to the supply noise, as compared to the conventional common‐source topology. The proposed common‐drain PA is implemented using a discrete LDMOS PD20010‐E RF transistor. Measurement results show that the PSRR of the proposed common‐drain PA is improved by up to 7 dB as compared to that of the common‐source PA. For a two‐tone input with 10 MHz bandwidth at the center frequency of 700 MHz, the power added efficiency (PAE) and IM3 of the envelope tracking common‐drain PA are 20% and ? 28 dBc, respectively, at an average output power of 33.4 dBm. The amplifier also shows a 12.4 dB power gain. Moreover, by utilizing the envelope tracking, the PAE is improved by more than 5%.     

The Programmer's Apprentice: Knowledge Based Program Editing

An initial implementation of an interactive programming assistant system called the programmer's apprentice (PA) is described. The PA is designed to be midway between an improved programming methodology and an automatic programming system. The intention is that the programmer will do the hard parts of design and implementation while the PA will assist him wherever possible. One of the major underpinnings of the PA is a representation (called a plan) for programs which abstracts away from the inessential features of a program, and represents the basic logical properties of the algorithm explicitly.     

Full-state perturbation analysis of discrete event dynamic systems

Discrete event dynamic systems are studied within the framework of perturbation analysis in this paper. Perturbation is extended from the event times only to both event times and queue lengths. An approximate technique, full-state perturbation analysis (PA), is developed as an extension of the PA approach. Full-state PA is able to deal with problems involving queue length perturbations which often defy existing PA methods, while it still retains all the advantages of existing PA. Full-state PA is used to calculate the throughput sensitivity to the number of customers in closed queueing networks and the throughput sensitivity to routing change. Numerical examples are given. Experimental results verify the validity and accuracy.This work is supported in part by the National High Technology Project and by Southeast University Research Funds for Young Teachers.     

宽带RF功率放大器的预失真线性化技术综述

随着无线需求和无线业务的不断增加,传输信号必将不断向高速率宽带宽发展。在宽带应用中,由于传输信号带宽增加,RF功率放大器不同于窄带输入下的无记忆特性,将表现出与频率有关的记忆非线性特性。针对宽带功率放大器线性化的记忆预失真技术成为当前研究的一个热点,综述了宽带RF功率放大器的预失真线性化技术的研究进展,详细介绍和分析了目前最主要的几种记忆预失真器的模型和对应的自适应预失真方案,最后给出了今后的研究方向。     

两亲性肽纳米纤维聚集的耗散粒子动力学模拟

根据PA分子基团的化学性质和粒子大小,将PA分子分成DPD粒子,将适当大小的水簇视为溶剂粒子,克服了模拟技巧的困难,首次用耗散粒子动力学(dissipative particle dynamics,DPD)方法模拟了两亲性肽分子PA的自组装相行为.模拟结果表明:在水溶剂的辅助下,在三维纤维状的圆柱聚合体中,这些分子能进行自组装.DPD的模拟结果受溶剂珠粒的大小、温度及PA与溶剂的比例等多种因素的影响.研究同时发现,在圆筒状纤维中,使用5～9个水簇的溶剂粒子可得到PA分子的聚合体.形成纳米纤维聚合体的条件是PA与水珠粒的比值大于1∶6,温度高于340 K.筒状聚合体直径的估计值符合实验测量值.