摘要：对于弹载红外探测器，要求具有高灵敏度，低噪声性能等特性，以利于提高探测距离，增加探测概率。除选择低噪声高灵敏红外探测器件以外，其探测器的微弱信号检测电路的设计尤显重要。本文重点讨论红外信号检测电路中前置放大器的低噪声设计方法。鉴于放大器本身会引入新的噪声，经多级放大再加上后级放大电路新引入的噪声，会对信号处理造成很大的困难，很难达到设计的探测距离。信号源的噪声也会经放大器被放大，本文结合实际项目着重考虑并以某个实际电路为例，详细说明如何通过噪声匹配尽可能的减小放大器本身引入的噪声；通过研究外围元件引入的热噪声对整个放大电路的噪声贡献，提出改善实际电路元件误差引起的噪声恶化的方法，以降低整个电路的噪声，从而提高探测距离。在具体生产实践中，在达到要求的探测距离的同时，也要尽可能的选用性能相对较差的低噪声运算放大器以及精度较低的电路元件，以降低成本和生产难度。我们也通过此电路研究在特定的情况下，放大电路各个元件的误差对放大器噪声性能的影响。60123

毕业论文关键词：红外探测器  低噪声运算放大器   噪声匹配  最佳源阻抗

毕业设计说明书（论文）外文摘要

Title    The Design of Signal Detection Circuit for Infrared Detector 

Abstract For infrared detector on missiles, high sensitivity and low noise are needed, so that range and ratio of detection can be increased. Aside from high sensitive and low-noise infrared detectors, it is much more important to design the feeble signal detection circuit. In this paper, we mainly discuss low-noise design method of designing the forward amplifier in infrared signal detection circuit. The amplifier will bring in additional noise, and this noise will then be amplified, so it is hard to deal with the signal mixed with noise and detection of the target will be impossible. Associated with real circuit design, we will discuss how to reduce the noise using noise matching method and analyse the white noise caused by different components, to propose a method of improving circuit performance, reducing noise, so that the range of detection can be increased. When it comes to manufacture, low-accuracy components should be used to reduce the cost while some high-accuracy components still used in specific points.

Keywords infrared detector; low-noise operational amplifier; noise matching; optimal source impedance

1引言 1

2  红外信号特点 2

2.1  目标红外辐射特征 3

2.2  红外测温电路 3

2.3  红外探测器 3

2.4  探测器输出信号 4

2.5  方案设计 4

3  放大电路 5

3.1  集成运算放大器 6

3.1.1  符号及理想化参数 6

3.1.2  集成运放的线性应用 6

3.2  运算放大器的噪声 8

3.2.1  电压噪声 8

3.2.2  电流噪声 9

3.2.3  实际电阻噪声 10

3.3  低噪声运算放大器（LNA）的主要指标 11

3.3.1  LNA的噪声系数和噪声温度