Circuit Topology Analysis of CMOS LNA in Mobile Communication Systems

1　Introduction　Now ,mostoftheLNAinRFreceiversarede signedwithGaAsorbipolartechnologies,whichhavealargepowerdissipationandunfavorableper formanceofintegration .CMOStechnologiestakeincreasinglyadvantagesoftechnologyadvances,whichhaveverylow powerconsumptionandmakepossibletheintegrationofcompletecommunicationsystems[1 ] .Forexample ,mobilecommunicationsystemreceiversemployextensivedigitalsignalpro cessingtoperformacquisition ,tracking ,anddecod ingfunctions.TheuseofCMOStechnologiesforimpl…     

一种阳极连接P型埋层的AlGaN/GaN肖特基二极管

在传统AlGaN/GaN肖特基二极管中,阳极漏电始终是制约器件耐压提高的一个重要因素。因此文中研究了在缓冲层中生长P型埋层并与阳极相连的AlGaN/GaN肖特基二极管结构 AC-PBL FPs SBD来抑制阳极的泄漏电流。同时,在二极管的两级均加上场板来调制该器件的表面电场分布。经过仿真验证可知,该结构的阳极关断泄漏电流得到了有效抑制,同时辅助耗尽沟道内的2DEG,扩大空间电荷区,进而提高了器件的耐压特性。该结构的击穿电压为733 V,与传统GET SBD器件相比,击穿电压提高了近3.4倍,Baliga优值提升了近11.6倍,说明该器件可以应用在电力电子线路中。     

An analysis of high-frequency noise in RF active CMOS mixers

An analysis of high-frequency noise in RF active CMOS mixers including single-balanced and double-balanced architectures is presented. The analysis investigates the contribution of non-white gate-induced noise to the output noise power as well as the spot noise figure (NF) of the RF CMOS mixer. It accounts for the non-zero correlation between the gate-induced noise and the channel’s thermal noise. The noise contribution of the RF transconductor and the switching pair to the output noise power is studied. Experimental results verify the accuracy of the analytical model. Payam Heydari (S’98–M’00) received the B.S. and M.S. degrees in electrical engineering from the Sharif University of Technology, in 1992, 1995, respectively. He received the Ph.D. degree in electrical engineering from the University of Southern California, in 2001. During the summer of 1997, he was with Bell-Labs, Lucent Technologies, where he worked on noise analysis in deep submicrometer very large-scale integrated (VLSI) circuits. During the summer of 1998, he was with IBM T. J. Watson Research Center, Yorktown Heights, NY, where he worked on gradient-based optimization and sensitivity analysis of custom-integrated circuits. Since August 2001, he has been an Assistant Professor of Electrical Engineering at the University of California, Irvine, where his research interest is the design of high-speed analog, RF, and mixed-signal integrated circuits. Dr. Heydari has received the 2005 National Science Foundation (NSF) CAREER Award, the 2005 IEEE Circuits and Systems Society Darlington Award, the 2005 Henry Samueli School of Engineering Teaching Excellence Award, the Best Paper Award at the 2000 IEEE International Conference on Computer Design (ICCD), the 2000 Honorable Mention Award from the Department of EE-Systems at the University of Southern California, and the 2001 Technical Excellence Award in the area of Electrical Engineering from the Association of Professors and Scholars of Iranian Heritage (APSIH). He was recognized as the 2004 Outstanding Faculty at the EECS Department of the University of California, Irvine. His name was included in the 2006 Who’s Who in America. Dr. Heydari Professor Heydari has been the Associate Editor of IEEE TRANS. ON CIRCUITS AND SYSTEMS, I, since 2006. He currently serves on the Technical Program Committees of International Symposium on Low-Power Electronics and Design (ISLPED), International Symposium on Quality Electronic Design (ISQED), and the Local Arrangement Chair of the ISLPED conference. He was the Student Design Contest Judge for the DAC/ISSCC Design Contest Award in 2003, the Technical Program Committee member of the IEEE Design and Test in Europe (DATE) from 2003 to 2004, and International Symposium on Physical Design (ISPD) in 2003.     

DVB-C系统中射频宽带低噪声放大器电路的设计研究

本文根据DVB系统对LNA的特殊要求,阐述了负反馈展宽放大器频带的原理,讨论了通过设计并联负反馈的手段来实现LNA宽频带稳定性,并在此基础上,设计出一种宽带LNA的拓补结构,并采用将负反馈解析计算与仿真优化相结合的LNA设计方法,给出了LNA最终设计的仿真及实测结果.实验结果和设计结果吻合较好.该LNA带宽为50 MHz～900 MHz,功率增益10.4 dB,带内增益波动0.6 dB,带内噪声系数2.7 dB～3.5 dB.     

改进的Hough变换圆检测算法

针对标准Hough变换在圆检测中对时间空间需求高的问题,提出一种改进的Hough变换圆检测算法。该算法将标准Hough变换检测圆时的三维空间转换为一维空间,利用圆为中心对称图形的几何特征计算圆心,然后通过一维Hough变换进行半径累积,得到圆半径。实验证明,该算法运行速度快,占用内存小,抗噪性能好,对单个圆和多个圆同样有效,具有较高的实用价值。     

直接耦合半导体光放大器的噪声特性

研究了直接耦合混合应变量子阱半导体光放大器(SOA)的噪声特性.实验中测定SOA在130 mA偏置电流下的噪声指数为7.7 dB,表明应变量子阱结构改善了SOA的噪声性能.理论分析指出,通过消除SOA的剩余反射,其噪声性能可以得到进一步改善.     

相控阵雷达接收系统噪声系数分析与测试验证

噪声系数是影响雷达接收机性能指标的主要参数之一,与雷达的作用距离紧密相关。文中采用将多端口网络转化为二端口网络的基本思想,对相控阵雷达接收系统的噪声特性以及增益进行了分析。首先,求出多端口网络的等效增益;再基于噪声系数的基本定义推出相控阵接收系统的噪声系数计算式;同时,基于等效的思想,提出了多端口网络噪声系数以及增益的直接测量方法;最后,用仿真以及实验验证了该计算及测量方法。     

接收机噪声系数分析

接收机的主要功能是将天线接收到的由目标反射回来的微弱射频信号进行放大、预选、变频、滤波等处理,使目标反射回来的微弱射频信号变成有足够幅度的视频信号或数字信号,以满足信号处理和数据处理的需要.灵敏度表示接收机接收微弱信号的能力,噪声是影响接收机灵敏度的主要因素.分析了接收机链路中主要器件的增益指标对接收机噪声系数的影响,给带宽宽、低噪声、高灵敏度接收机的设计提供借鉴和参考.     

基于脉冲样本图的雷达辐射源识别新技术

现代雷达信号体制越来越复杂,使得现有的雷达信号特征描述方式很难有效地对复杂体制辐射源进行描述分析。为解决复杂体制雷达辐射源的识别问题,文章提出了一种新的雷达信号描述方式——脉冲样本图,并设计了一种可以对其进行分类识别的BP(Back Propagation)网络。仿真实验表明该网络可以对脉冲样本图进行有效识别,为解决复杂体制雷达辐射源的识别提供了新思路。     

接收机射频前端噪声特性分析

噪声是影响接收机灵敏度的重要因素之一。接收机引入的噪声越小,接收机灵敏度就越高。分析了接收机噪声,给出了射频前端噪声系数与接收机灵敏度的关系,论述了几种改善射频前端噪声系数的方法。