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摘要本论文介绍了K波段低噪声放大器的原理电路设计的方法，给出了仿真优化的结果。本论文设计的K波段低噪声放大器(LNA)选择三菱公司的HEMT管芯，由于增益的要求，本文的LNA设计采用了三级放大的拓扑结构，各级管芯都设计了相应的偏置电路。匹配网络采用了微带线进行设计，输入输出均匹配到50欧姆。
为了保证电路有合适的静态工作点，在对电路的工作状态，频率响应，稳定性进行分析之后，我设计了一个无缘偏置网络，在带内是让直流电源与传输线信号隔离，形成滤波网络，滤除RF信号，尽量只让直流通过。这样，一方面无论何种电源都不会对放大器的带内特性产生影响，同时也可以保证晶体管的匹配电路不受影响；另一方面偏置电路内有耗元件产生的噪声不会给放大器引入太多额外的噪声。64185
由于各级电路均设计有输入输出匹配，因此在进行各级放大器级联时，采用了直接相连的方法。此外为了提高电路性能，我还在第二第三级电路的源级添加了负反馈网络。这一网络在保证电路噪声基本不变的前提下，改善了电路的整体性能。最后我对布局进行了再优化，以得到最佳的仿真结果。
最后实现的该K波段低噪声放大器工作在19．5~21．5GHz，在工作频带内噪声系数低于2.5dB、增益超过30dB、达到了设计指标的要求。
毕业设计说明书（论文）外文摘要
Title A Design Of k-Band Low Noise Amplifier Circuit
Abstract This paper introduces the principle of k-band LNA circuit design and layout design method, gives the result of simulation.
Due to requirements of gain, the k-band LNA chooses HEMT of mitsubishi in this paper, the LNA design uses the three-stage amplifier topologies with bias circuit . Matching network use microstrip line design, input and output are matched to 50 ohm.
In order to guarantee the circuit has the appropriate static work, the frequency response of the circuit operating conditions, stability, after analysis, I design a no bias network, in the zone is to make the DC power transmission line and signal isolation, forming a filter network, filter the RF signal, try to just let the DC through. In this way, on one hand no matter what kind of power supply has no influence on the band characteristics of the amplifier, but also can ensure the matching circuit of transistor is not affected; on the other hand, the bias circuit noise does not produce oxygen element to the amplifier noise is introduced too much extra.
Because various circuit are designed with input and output matching, so in all levels of amplifier cascade, using the method of directly connected. In addition, in order to improve the circuit performance, I design a negative feedback network in second and third grade circuit. This network is used to guarantee the circuit noise basically unchanged and improve the overall performance of the circuit. Finally I optimize the layout of the circuit, in order to obtain the best simulation results.
The K band LNA work finally realized in 19.5~21.5GHz, in the working frequency band noise coefficient is lower than 2.5dB, gain of more than 30dB, meet the design requirements.
Key words: K band, high electron mobility transistor, low noise amplifier
目 次
1 绪论 1
1.1低噪声放大器的研究意义 1
1.2低噪声放大器的发展状况 1
1.3本课题研究内容及工作安排 2
2 低噪声放大器的基本原理