锁定放大器的微弱信号检测装置设计

Design of the Weak Signal Detection Device for Lock-in Amplifiers

由于被测信号弱、电路中噪声大等缘故,需要对信号进行放大处理,同时动态范围也要扩大。文章针对信号检测中呈现的信号弱、信噪比低等问题,探索研制一种锁定放大器的微弱信号检测装置,并基于锁定放大器相敏检波原理进行总体方案的硬件电路设计和软件设计,给出MSP430单片机程序,通过单元测试和联合调试,表明对于1 kHz的100μV微弱正弦波信号,在有效值信噪比1∶10情况下,LCD显示结果与实际值误差小于10%,达到预期研究目标。

Due to the weak signal under test and high noise in the circuit,the signal needs to be amplified and the dynamic range needs to be expanded.In view of the problems of weak signal and low signal-to-noise ratio presented in signal detection,a weak signal detection device for the lock-in amplifier,is explored and developed.Besides,the overall design of the hardware circuit and software is carried out based on the phase-sensitive detection principle of the lock-in amplifier,and the MSP430 MCU program is given.Through unit testing and joint debugging,it is shown that for a 100μV weak sine wave signal at 1KHz,the error between the LCD display and the actual value is less than 10%when the effective signal-to-noise ratio is 1∶10,which achieves the expected research goal.