基于锁相放大原理的微弱信号检测电路

Weak signal detection circuit based on lock-in amplifier

针对目前成品锁相放大器价格昂贵且体积大,传统窄带滤波法性能和灵活性差的特点,设计了基于锁相放大器原理的微弱信号检测电路。本电路采用单片机作为激励信号和参考信号的发生器,利用带关断引脚的运放实现相敏检波器,整个电路仅使用了5个运算放大器和一些阻容元件。实验表明,本电路能实现了从信噪比为0.1的被测信号中提取有用信号幅值的功能,测量误差控制在5%以内。由于本电路有实现简单和成本低的特点,稍加修改后可作为模块电路用到其他测量系统当中。

In view of that the present lock-in amplifier is expensive and its volume is large, and the performance and flexibility of the traditional narrow-band filtering method is bad, design a weak signal detection circuit based on the principle of lock-in amplifier.This circuit use a MCU as drive signal and reference signal generator, and use op-amp with shutdown pin to realize phase sensitive detector. Experiments show that this circuit can achieved the purpose of extracting useful signal from a signal with SNR of 0.1, the total measuring error is within 5%. Because the circuit is simple and low cost, it＇s easy to be use in other measurement system with slight modification.