摘要
基于低噪声电路设计原则,给出了一种用于核磁共振测井仪的前置放大电路.电路采用低噪声双极性晶体管MAT02作为第一级放大,采取负反馈稳定电路的增益,然后经过低噪声集成运放进行第二级放大,从而可提高整个前置放大电路的噪声性能.通过等效噪声模型的方法,定量计算了整个电路的噪声特性,同时得到了设计低噪声电路的一般性结论.计算表明:电路在源电阻为96Ω的情况下,电路的最低噪声系数为1.5dB;电路的等效噪声电压为0.57 nV/Hz,在经过屏蔽的实验环境下,测得的等效噪声电压约为0.87 nV/Hz.
Based on the design principles of low-noise circuit, magnetic resonance logging tools was presented. The circuit as first-level amplification and stability to take negative feedb a preamplifier circuit structure of nuclear used low-noise bipolar transistor MAT02 ack circuit gain, and then integrated lownoise operational amplifier for the second-level amplification, thereby improved the preamplifier circuit noise performance. Using the equivalent noise model, the entire circuit＇s characteristics of the noise were quantitative calculated. Relevant conclusions were drawn. Results of calculation showed that the best source resistance was 96 ohm and the smallest noise figure was 1.5 dB; the equivalent noise voltage was 0.57 nV/√Hz and in the shielding experimental environments, the test result showed that noise voltage was 0.87 nV/√Hz.
出处
《华中科技大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2008年第1期91-94,共4页
Journal of Huazhong University of Science and Technology(Natural Science Edition)
基金
国家高技术研究发展计划重点资助项目(2006AA060101)
中国石油天然气集团公司重大科研基金资助项目(06B3020)
关键词
核磁共振测井
前置放大电路
等效噪声模型
噪声系数
NMRL （nuclear magnetic resonance logging）
preamplifier circuit
equivalent noise model
noise figure
