低噪声放大器仿真及优化毕业设计论文.doc

低噪声放大器设计仿真及优化 摘 要 快速发展的无线通信对微波射频电路如低噪声放大器提出更高的性能。低噪声放大器(LNA)广泛应用于微波接收系统中，是重要器件之一，它作为射频接收机前端的主要部分，其主要作用是放大天线从空中接收到的微弱信号，降低噪声干扰，以供系统解调出所需的信息数据。它的噪声性能直接决定着整机的性能，进而决定接收机的灵敏度和动态工作范围。而近年来由于无线通信的迅猛发展也对其提出了新的要求，主要为：低噪声、低功耗、低成本、高性能和高集成度。所以本论文针对这一需求，完成了一个2.45GHz无线射频前端接收电路的低功耗低噪声放大器的设计。 本文从偏置电路、噪声优化、线性增益及输入阻抗匹配等角度分析了电路的设计方法，借助 ADS 仿真软件的强大功能对晶体管进行建模仿真，在这个基础上对晶体管的稳定性进行了分析，结合 Smith 圆图，对输入输出阻抗匹配电路进行了仿真优化设计，设计了一个中心频率为、带宽为、输入输出驻波比小于、和增益的放大器。 微波仿真ABSTRACT Rapid growth of wireless data communications has increased the demand for high performance RFMicrowave circuits, Such as Microwave Low Noise Amplifiers. The LNA is one of the most important and broad components in Microwave communication system receiver, as the main part of the RF front-end receiver, the function of the low noise amplifier is amplifying the faint signal which incepted from air by the antenna. It can reduce the noise jamming, so as to demodulate right information for the system. The noise performance of the LNA will affect the performance of the whole system directly, and then deciding the sensitivity and dynamic working scope of the receiver. From the aspect of bias circuit, noise optimization, linear gain, impedance match, and the design methodology for LNA is analyzed, This article carries on the modelling simulation with the aid of the ADS simulation softwares powerful function to the transistor, has carried on the analysis in this foundation to transistors stability, has used the Smith circle diagram, to input the output impedance match circuit to carry on the simulation optimization design. a radio frequency power amplifier is designed, which has a centre frequency2.45GHz, bandwidth 100MHz, I/O VSWR less than 1.5, Noise coefficient less than 2dB and Wattandgain 15dB. Key Words：microwave low-noise amplifier; noise figure; matching circuit; ADS simulation 目 录 1 引 言 1 1.1 课题研究背景 1 1.2 低噪声放大器简介 2 1.3 低噪声放大器的发展现状 2 1.4 本课题的研究方法及主要工作 3 2 低噪声放大器理论综述 5 2.1 史密斯圆图 5 2.2 S参数 6 2.3 长线的阻抗匹配 7 2.3.1 微波源的共轭匹配 7 2.3.2 负