摘要
针对井下地层流体核磁共振分析仪器回波信号的频率高、强度弱、信噪比低的特性,以及测井仪器工作环境的特殊性,设计了一种低噪声的微弱信号放大电路。电路以低噪声双极性晶体管MAT02为核心的负反馈放大电路作为第一级放大,采用低噪声集成运放AD8130作为第二、三级放大,改善了微弱信号放大电路的噪声性能。实验表明:该电路对于频带4~5 MHz微弱信号,增益可达70 d B,且其等效输入噪声电压为槡2.1 n V/Hz,同时在环境温度0~150℃时有良好的线性度、较平坦的带宽和优良的低噪声性能,可为测井仪器中较高频率的微弱信号测量研究提供参考。
Aiming at the characteristics of high frequency,low intensity,low SNR of the underground formation fluid nuclear magnetic resonance（NMR） analysis instrument echo signal and the particularity of the logging instrument working environment,low noise weak signal amplification circuit was designed.Negative feedback amplifying circuit with low noise bipolar transistor MAT02 as core was the first level amplification.And the low noise integrated operational amplifier AD8130 was used as the second and third level amplification,so as to improve the noise performance of the preamplifier.Experimental results show that the frequency band is 4 - 5 MHz,receiving circuit gain is 70 d B,and its equivalent input noise voltage is 2.1 nV/Hz.which has good linearity,relatively flat bandwidth and excellent low noise performance at the environmental temperature of 0 - 150 ℃,providing a reference for the logging instrument in high frequency weak signal measurement study.
出处
《仪表技术与传感器》
CSCD
北大核心
2017年第2期27-30,共4页
Instrument Technique and Sensor
基金
高等学校博士学科点专项科研基金(20130142120065)
