【作者】 杨凯；

【导师】 王春华；

【作者基本信息】 湖南大学 ， 通信与信息系统， 2008， 硕士

【摘要】 近年来,超宽带技术(UWB)作为一种新兴的无线通信技术成为了研究的热点。低噪声放大器(LNA)是超宽带系统接收前端最重要的模块,其噪声性能直接影响整个系统的噪声性能,所以对于超宽带低噪声放大器的研究具有重要的意义。本文首先介绍了超宽带低噪声放大器的研究现状和意义,并引出了增益可调超宽带低噪声放大器研制的必要性;然后系统地概述了超宽带低噪声放大器的基本理论;最终设计出了性能比较优越的连续增益可调的超宽带低噪声放大器。本文所做的工作和创新如下:(1)总结和分析了当前超宽带低噪声放大器的各种结构,对其小信号模型,噪声模型作了分析并比较了它们的优缺点;(2)对现有的增益可调技术作了简要地介绍,比较了它们的优缺点;(3)设计出一种3-5GHz的具有大范围连续增益变化的CMOS可调增益低噪声放大器,采用两极的共源共栅电路结构,二阶切比雪夫滤波器作为输入,源极跟随器作为输出,在带内获得了良好的输入输出匹配和噪声性能。通过控制第二级的偏置电流,获得了36dB的连续增益可调,同时也不影响输入输出匹配.该电路在最高增益时输入和输出反射系数S11和S22分别小于-10.1dB和-15dB,最高增益达到23.8 dB,最小噪声系数只有1.5dB,三阶交调截点为-7dBm,在1.2V的供压下,功耗为6.8 mW。(4)提出应用于3-10GHz的连续增益可调的低噪声放大器,采用共栅输入,并利用一个简单的高通滤波器置于输入端和电感峰化来实现3-10GHz的宽带匹配。同样也是通过控制第二级的偏置电流来实现连续增益可调,同时也不影响输入输出匹配。其电路性能如下:连续增益可调范围是19dB,输入和输出反射系数S11和S22分别小于-10.3dB和-10.6dB,在12.4dB的最高增益时,最小噪声系数为3.28 dB,在1.5V的供压下直流为13.1mA.本文提出的电路由ADS软件仿真,采用TSMC 0.18μm CMOS工艺,并利用Candence软件画出版图和后仿真,前仿和后仿结果与当前发表过的UWB LNA相比,具有很大的优越性,并实现了超宽带低噪声的连续增益可调的功能。更多还原

【Abstract】 In recent years, the Ultra Wide-Band (UWB) technology as a novel wireless communication technology has become a hot research. A low noise amplifier (LNA) is one of the most critical blocks in the receiver front-end of UWB systems, which determines the performance of the whole receiver.So it is very significant to research on UWB LNA.The paper briefly introduces the research status and significance of UWB LNA, and illustrates that it is necessary to design a variable gain UWB LNA firstly.Then the basic theory of low noise amplifier (LNA) is summarized systematically. Finally,a CMOS continuous variable gain UWB LNA is presented.The main achievements of this work consist of following aspects:(1) The current various configurations of UWB LNA including their small-signal model and noise model are analyzed and summarized systematically.Also thier advantages and disadvantages are compared.(2) The existing variable gain methods are introduced and compared.(3) A tow-stage CMOS variable gain LNA (VG-LNA) with large and continuous gain variation for 3-5GHz is presented. A tow-section Chebyshev filter is exploited to achieve excellent input match in the band and to optimize the noise performance. An source-follower is designed specially to match output. By controlling the bias current of the second stage, a continuous gain tuning range of 36dB is achieved without influencing the input match and output match. The VG-LNA shows the following performance at the highest gain:S11and S22 are less than -10.1dB and -15dB respectively, and 23.8dB peak gain, only 1.5dB minimum noise figure,-7dBm input-referred third-order intercept point, while dissipates 6.8 mW from a 1.2V supply.(4)A new CMOS variable gain LNA (VG-LNA) with continuous gain variation for 3-10GHz is presented. With the common-gate configuration and a simple high-pass filter employed as the input stage, the broad-band input matching is obtained. By controlling the bias current of the second stage, a continuous gain tuning range of 19dB is achieved without influencing the input match and output match. Its performance at the highest gain mode is as follows: S11 and S22 are less than -10.3dB and -10.6dB respectively, and 12.4dB peak gain, 3.28dB minimum noise figure, while drawing13.1mA from a 1.5V supply.The proposed circuits are simulated in TSMC RF CMOS 0.18μm technology by ADS2006, and the layout and post-layout simulation are used by Candence. The pre-layout simulation and post-layout simulation results show that it is more excellent than recently published CMOS designs, and the function of continuous variable gain for UWB LNA is achieved.更多还原