摘要低噪声放大器（LNA）对微波接收系统的接收灵敏度和噪声性能起决定性作用。用PHEMT制作的多级 LNA已经广泛用于卫星接收系统、雷达系统等各种电子系统之中。

本论文分析了LNA工作原理，并对C波段LNA电路进行了研究与设计。放大器电路采用三级设计，选用晶体管ATF36077和微波单片放大器MGA86576设计。通过一系列的综合仿真与分析，逐步完成偏置电路、匹配网络的设计。将反馈微带线加在源极，提高了电路的稳定性，在晶体管的栅源之间加入负反馈网络提高了电路的增益平坦度，减小输入输出驻波比。使用ADS的优化功能进行全部电路的优化。仿真结果表明，设计的LNA电路工作在3.7GHz-4.2GHz波段，增益大于 41.5dB，噪声系数小于 0.5dB，通带内增益起伏小于1.5dB，输入输出驻波比小于1.5，达到了设计指标的要求。63686

毕业论文关键词  微波  低噪声放大器  PHEMT  C波段

毕业设计说明书（论文）外文摘要

Title  Design and Simulation of C-band Low Noise Amplifier 

Abstract Low Noise Amplifier (LNA) plays adecisive role on the entire system receiving sensitivity and noise performance. Multistage low noise amplifiers with HEMT are widely used in satellite receiving systems, electronicsystems and radar systems.

This paper analyzes the LNA works based on the C-band low noise amplifier circuit design research. The circuit is made up of three stages with ATF-36077 and MMIC amplifier MGA86576. Matching circuits of Bias circuit, input stage, middle stage and output stage have been implemented through simulation analysis. Feedback microstrips are added to source electrode to improve stability of the circuit，negative feedback network is added to the transistor between gate and source in the third stage to improve the circuit's gain flatness and input-output VSWR. The whole circuit is simulated and optimized by ADS. Simulation results show that the low-noise amplifier operating at 3.7GHz-4.2GHz, the gain is greater than 41.5dB, noise figure less than 0.5dB, gain variation within the passband is less than 1.5dB, input and output VSWR less than 1.5, which meets the design specification requirements .

Keywords  Microwave  LNA  HEMT  C-band 目   次

1 绪论..3

1.1关于C波段 3

1.2 低噪声放大器的应用与分类 3

1.3 低噪声放大器的研究意义与发展现状 4

1.4 论文内容安排 4

2 放大器电路的基本理论 6

2.1 二端口网络 6

2.2 判定放大器稳定性 7

2.3 放大器增益 8

2.4 微波放大电路中的噪声 10

2.5 端口驻波比VSWR 10

2.6 工作频段与带宽 11

2.7 增益平坦度 11

2.8 匹配理论 11

2.9 微波传输线与微带线 12

2.10 小结 14

3 方案选择 ..15

3.1 微波双极晶体管 15

3.2 异质结双极晶体管 15

3.3 场效应器件 15

3.4 器件的选择 16

3.5 方案确定 16

3.6 小结