超声探伤自动扫描平台微弱信号放大电路设计  

Circuit design of weak signal amplification for ultrasonic testing automatic scanning platform

作　　者：马卫卫[1] 贺洪斌[1] 江灿 温家炜 陈浩[1,2] 翟勇 MA Weiwei;HE Hongbin;JIANG Can;WEN Jiawei;CHEN Hao;ZHAI Yong(Institute of Acoustics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shengli Well Logging Company,Sinopec Matrix Corporation,Dongying 257061,China)

机构地区：[1]中国科学院声学研究所,北京100190 [2]中国科学院大学,北京100049 [3]中石化经纬有限公司胜利测井公司,东营257096

出　　处：《应用声学》2025年第2期480-488,共9页Journal of Applied Acoustics

基　　金：国家自然科学基金项目(42304142)。

摘　　要：超声探伤自动扫描平台在工作中,空气耦合超声探头输出信号小,且受电机噪声及外界噪声的干扰,因此对检测系统的噪声要求高。为有效地检测并提取微弱信号,该文设计一种具有抗干扰的超低噪声、高增益且增益连续可调的宽带放大电路。放大电路由一级低噪声前置放大电路和由低噪声、可变增益放大器组成的两级级联电路构成。第一级放大器采用具有超低噪声、高输入阻抗、高共模抑制比的前置放大器,根据噪声系数设计合适的反馈电路,达到最佳的噪声匹配。后两级电路可实现增益080dB连续可调。测量结果表明,电路整体增益在20100dB连续可调,能够检测到空气耦合探头微伏级信号,可广泛应用于弱信号检测中。In the operation of the automatic scanning platform for ultrasonic testing,the output signal of the air-coupled ultrasonic transducer is small,and there is interference from motor noise and external noise.Therefore,the noise requirements for the detection system are high.In order to detect and extract weak signals effectively,this paper designs an amplification circuit with anti-interference,ultra-low noise,high gain,and continuously adjustable gain.The amplifier circuit consists of a first stage ultra-low noise preamplifier circuit and a two-stage cascaded circuit composed of low noise,variable gain amplifiers.This circuit design adopts a preamplifier with very low input noise,high input impedance,and high common mode suppression ratio.Based on the noise coefficient of the circuit,a suitable feedback circuit is designed to achieve optimal noise matching.The last two-stage circuit can achieve continuous adjustable gain of 0–80 dB.The measurement result indicates that the overall gain of this circuit is continuously adjustable between 20 dB and 100 dB and can detect weak signals of air-coupled ultrasonic transducer and can be widely used in weak signal detection.

关 键 词：空气耦合超声 微弱信号检测 噪声系数 超低噪声 高增益 

分 类 号：TH878[机械工程—仪器科学与技术]