核磁共振测井仪前置放大电路设计

The Design of NMR Logging Preamplifier

核磁共振回波信号微弱,设计一种低噪声前置放大电路是回波信号提取的关键。给出天线的等效模型,提出天线与前置放大电路接口设计原则,依据采集电路对输入信号信噪比的要求设计并实现一种低噪声前置放大电路。温度、增益、带宽、噪声性能实验结果表明电路各项指标与设计计算相符并达到仪器要求。

Designing a low noise preamplifier is the key to the echo signal extraction owing to weak NMR echo signal.Give the antenna＇s equivalent model,put forward the design principle of the antenna and preamplifier interfaces.According to the requirement of the input signal SNR,design and achieve a circuit of low-noise preamplifier.The experimental results of temperature,gain,bandwidth,noise performance show that all indexes of circuit comply with the design calculations and equipment＇s requirements.