一种适用于微弱传感信号检测的锁相放大电路

针对复杂噪声环境中有效提取出微弱传感信号的问题，设计了一种实用的锁相放大器电路。该设计通过产生两路正交的矢量参考信号与经低噪声放大和带通滤波后的被测信号相乘实现信号相位差检测，经过低通滤波和均方根计算等实现对微弱信号的提取。该设计采用了一种基于变换的方波乘法器，实现了动态范围宽、直流漂移小、线性度高的乘法运算，进一步提高提取信号的精度。测试结果表明，该设计不但提取的信号精度高，而且电路结构简单，对元件一致性要求低，克服了普通放大器需要被预知被测信号和参考信号相差的问题。

Design of lock-in amplifier circuit and developed for weak signal detection

In order to extract weak sensing signal, a practical lock-in amplifier circuit is designed. By generating two orthogonal vector reference signals multiplied by the measured signal after lowing noise amplifier and band pass filter, then through the low pass filter and mean square root calculation for weak signal extraction. A kind of square wave multiplier based on changes is also applied to achieving multiply operation of wide dynamic range, DC drift of small and high linearity and making the extraction of signal with higher accuracy. The test results indicate that the design not only improves the accuracy of the signal and makes the circuit structure simple, but also reduces the requirements of element consistency and the problems of the general amplifier which needs to be predictive that measured signal and the reference signals are different have been overcome.