地球物理勘探用高精度隔离放大器  

High precision isolation amplification instrument for geophysical exploration

作　　者：颜良[1,2] 陈儒军[1,3,4] 

机构地区：[1]中南大学信息物理工程学院,长沙410083 [2]东方地球物理公司大型地震仪器项目组,涿州072751 [3]东方地球物理公司综合物化探事业部,涿州072751 [4]中南大学计算机科学与技术博士后流动站,长沙410083

出　　处：《地球物理学进展》2009年第2期763-767,共5页Progress in Geophysics

基　　金：国家“十五”科技攻关计划项目(2001BA609A-5)资助

摘　　要：地球物理勘探在野外进行,测量的电信号振幅范围为n×100uV～n×1 V,对电信号测量精度要求优于0.1%.这就要求相应的隔离放大器增益范围大,档差小,温漂小.为了满足上述要求,设计的精密隔离放大器由高线性度高精度器件一隔离放大芯片AD202组成隔离级,3个零漂移运放LT1250组成3级9档放大级,档差为10 dB,增益从0～90 dB可控.实际电路的测试结果表明:基于AD202和LT1250设计的隔离放大器的最大非线性误差为0.23%,19小时内的漂移为27 uV,达到了设计要求.A high precision isolation amplifier for front-end electrical filed conditioning and sampled current signal isolation amplification is introduced. The instrument is composed of the input buffer circuit, the first stage amplifier and the low-pass filter with gain as 0 dB, 10 dB, 20 dB, 30 dB, the second stage amplifier and the low-pass filter with gain as 0 dB, 10 dB, 20 dB, 30 dB, the third stage amplifier and the low-pass filter with gain as 0 dB, 10 dB, 20 dB, 30 dB, the isolation stage with high linearity, high precision isolation amplifier AD202, the output stage with lowpass filter, gain control circuit, and overload detection and indication circuit. It offers a total gain the 90 dB; ensures proper amplification of small signal less than 100 uV. To test the instrument, the small signal input test, the frequency response test, and the non-linearity test and drift test are carried out. Test results show that the maximum nonlinear error of the isolation amplifier based on AD202 and LT1250 is 0. 23M. Its drift is 37 uV in 19 hours,reacheing the requirement of the design.

关 键 词：隔离放大器 地球物理勘探 AD202 LT1250 

分 类 号：P631[天文地球—地质矿产勘探]