用于微弱信号检测的锁定放大器设计  

Design of a lock-in amplifier for weak signal detection

作　　者：孙倩[1] 付虹[1] 杨本全[2] 

机构地区：[1]长春工业大学电气与电子学院,吉林长春130012 [2]台州学院,浙江台州318000

出　　处：《传感器世界》2015年第6期31-36,共6页Sensor World

摘　　要：以嵌入式微处理器C8051F020为控制核心,结合锁相放大原理完成微弱信号检测,系统主要由纯电阻分压网络、加法器、带通滤波器、相敏检波、移相器及ADC采集和单片机控制显示等电路组成。系统以相敏检波器为基础,其中加法器和纯电阻分压网络生成微小信号,将微小信号经过交流放大电路和带通滤波器进行选频放大,输出给相敏检波器的一端;将参考信号经过移相器移相,再经过比较器产生方波,相敏检波器比较两路信号后产生直流信号,最后经低通滤波器和放大器输出直流信号并检测出微弱信号,将直流信号经AD7705采样送入单片机处理后,通过液晶显示。经测试,本系统能较好地完成微弱信号的检测。Embedded the microcontroller processor C8051F020 as the core, and combined with the principle of phase- locked amplifier, the system completes weak signal detection. The system is mainly composed of pure- resistance potential divider network, adder, band-pass filter, phase sensitive detector, phase shifter, ADC collecting circuit and single-chip microcomputer control circuit, etc. The system is based on phase sensitive detector. The adder and the pure-resistance potential divider network generate a tiny signal, which is transferred to the phase-sensitive detector after frequency selection and signal amplification through AC amplifying circuit and a band-pass filter. The reference signal is to the other input end of the phase- sensitive detector after being phase shifted through the phase shifter, converted into square wave through thecomparator .The phase-sensitive detector compares two signals and generates a DC signal, and completes detection of weak signal through the low-pass filter and amplifier After sampled by AD7705 the DC signal is sent into the microcontroller and displayed on the LCD. The tests show that this system can complete the weak signal detection

关 键 词：锁相放大器 带通滤波器 相敏检波 

分 类 号：TN722[电子电信—电路与系统] TN911.23