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在红外系统中,探测器把来自目标的弱辐射信号转换成微弱的电信号.为了不恶化探测器输出的信噪比,前置放大器的噪声必须很低,使红外系统的灵敏度主要由探测器输出的信噪比决定.本文在分析电阻性信号源晶体管放大器噪声特性的基础上,把探测器、偏置电路和前置放大器作为整体,导出偏置电路元件的选择原则和对第一级晶体管噪声特性的要求.介绍了几个用于实际红外系统中锑化铟(InSb)、碲镉汞(HgCdTe)、硫化铅(PbS)和钽酸锂(LiTa?3)等探测器的前置放大器电路.
In the infrared system, the detector converts the weak radiation signal from the target into a weak electrical signal.In order not to deteriorate the signal to noise ratio of the detector output, the noise of the preamplifier must be very low so that the sensitivity of the infrared system is mainly determined by the detector Output signal to noise ratio decision.In this paper, based on the analysis of the noise characteristics of the resistive signal source transistor amplifier, the detector, the bias circuit and the preamplifier as a whole, the principle of deriving the bias circuit components and the first stage transistor Noise characteristics.Presents several preamplifiers used in the detectors of InSb, HgCdTe, PbS and LiTa? 3 in real infrared systems. Circuit.