低噪声高增益锁相放大的微弱信号检测系统  

Weak signal detection system based on phase-locked amplification with low noise and high gain

作　　者：王琦[1] 蒋川东[2] 杜海龙[1] 

机构地区：[1]吉林大学通信工程学院,吉林长春130000 [2]吉林大学仪器科学与电气工程学院,吉林长春130000

出　　处：《实验技术与管理》2018年第3期84-86,100,共4页Experimental Technology and Management

基　　金：国家自然科学基金青年项目(41604083;41704103)

摘　　要：设计了基于低噪声高增益发大技术、锁相放大技术和高速高精度采集技术相结合的微弱信号检测系统,该系统采用ARM和FPGA为控制核心,由程控放大模块对待测信号进行宽带滤波和高增益放大,通过双锁相放大器将信号分解成2个正交分量,由24位模数转换器进行高速率采集,实现微弱信号的高精度检测,并通过网口与上位机实时通信和波形显示。测试表明,该系统可将被测信号放大10~8×10~6倍,输入短路噪声低至2nV·Hz^(-1/2),最大可调带宽为10kHz,时间常数3~30 ms,采样速率为52.734kHz,成功检测到239.60nV随时间衰减的核磁共振信号,可用于电子类专业本科实验教学。In order to realize the detection of the narrow band weak signal,a weak signal detection system based on the combination of the low noise and high gain amplification technology,phase-locked amplification technology and high speed and high precision acquisition technology is designed.The ARM and FPGA are used as the control core.Firstly,the wide-band filtering and high gain magnification of the signal to be measured are performed by the program control amplification module.Secondly,the signal is decomposed into two orthogonal components through a dual phase locked amplifier.Finally,the high-speed rate acquisition is carried out by 24 bit analog/digital converter to realize the high precision detection of the weak signal,and the real-time communication and waveform display are performed through the network port and the upper computer.After the laboratory test,the system can amplify the signal to be measured by 10—8×10~6,reduce the input short circuit noise to as low as 2 nV·Hz^(-1/2),adjust the maximum bandwidth to 10 kHz,keep the time constant between 3—30 ms,and make the sampling rate at 52.734 kHz.The 239.60 nV nuclear magnetic resonance signal with time attenuation is successfully detected,which can be used for the undergraduate experimental teaching of the electronics majors.

关 键 词：微弱信号 高增益 低噪声 锁相放大 

分 类 号：TN722[电子电信—电路与系统]