低场磁共振的信号源和功放前级  

Signal Source and Primary Power Amplifier of Low Field NMR System

作　　者：傅元[1] 初振东[1] 

机构地区：[1]沈阳工业大学信息科学与工程学院,辽宁沈阳110870

出　　处：《仪表技术与传感器》2014年第2期102-104,共3页Instrument Technique and Sensor

摘　　要：介绍了一种低场核磁共振系统激励信号源和功率预放大电路的设计和实现。电路主要包括单片机控制电路、DDS电路、激励幅度调整电路、滤波器电路、时间闸门电路、功率预放大电路。功率预放大电路利用功率高频三极管构成甲类功放,同时配有双路积分器,对功率放大器的静态工作点进行自动跟踪,保证功率放大器工作点的热稳定性。试验表明,电路结构简单实用,对于低场核磁共振系统,具有一定的通用性。This paper introduced a kind of power excitation source circuit for the nuclear magnetic resonance system. The pow- er excitation source consisted of the MCU circuit, DDS circuit, elliptic filter circuit, time gate circuit and power amplifier circuit. The power amplifier circuit is a class A power amplifier with RF power transistor and two integrators. The two integrators can auto- matically track the quiescent operation point of the power amplifier circuit and make the output of the power amplifier circuit more stable. Experiments show that the circuit is simple, practical and it can be generally used in the low field NMR system.

关 键 词：核磁共振 DDS 功率放大器 椭圆滤波器 传输线变压器 

分 类 号：TH862[机械工程—仪器科学与技术]