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本文设计了一种基于相敏检波的锁定放大器,用来检测被噪声淹没的微弱信号。本设计主要由信号通道、参考通道、相敏检波器及低通滤波器组成。信号通道主要包括分压电路、交流放大器和带通滤波器。参考通道主要包括触发整形电路、移相器,生成可以驱动相敏检波器的方波信号。信号经过相敏检波器、低通滤波器后变成直流信号,将输出的直流信号放大后进行AD采样,经过简单的幅度换算后将微弱信号的幅度显示在液晶屏上。
In this paper, a lock-in amplifier based on phase-sensitive detection is designed to detect weak signals submerged by noise. The design of the main signal channel, reference channel, phase sensitive detector and low-pass filter. Signal channels include voltage divider circuit, AC amplifier and band-pass filter. The reference channel mainly includes trigger shaping circuit, phase shifter, generate square wave signal that can drive phase sensitive detector. Signal through the phase-sensitive detector, low-pass filter into a DC signal, the output of the DC signal amplified after AD sampling, after a simple amplitude conversion will weak signal amplitude displayed on the LCD screen.