一体化NMR波谱仪梯度-场频联锁-匀场系统设计

摘要

The design of an integrated gradient-field/frequency lock-shim system for NMR spectrometer is presented. The integrated architecture is realized by combining embedded ethernet, field programmable gate array (FPGA) , external memory interface (EMI), controller area network (CAN) bus and high-speed serial bus technologies, making the system compact and reliable. The system consists of three parts: (1) the field/frequency lock subsystem which ensures the stability of the magnetic field, (2) the shim subsystem which guarantees the consistency of the magnetic field, and (3) the gradient amplifier which generates the gradient field pulse. Due to its flexibility, the design can easily be adapted for different NMR spectrometers. The feasibility of the integrated system is illustrated by tests of the shim, lock and gradient outputs on a 11. 7 T NMR spectrometer.%介绍一体化核磁共振波谱仪梯度-场频联锁-匀场系统的设计方案.该方案使用嵌入式以太网、FPGA(Field Programmable Gate Array,现场可编程门阵列)、EMI(External Memory Interface,外部存储器接口)和高速串行总线等技术构建了基于以太网的通信系统和使用并行运算的控制系统,并具备CAN(Controller Area Network,控制器局域网)总线通信的能力.梯度放大器通过LVDS(Low-Voltage Differential Signaling,低压差分信号传输)接口与主控系统的梯度波形发生器连接,实现与谱仪工作站的交互.系统采用插板式结构和通用性电路的设计方法,具有很好的扩展能力和适应性,能够满足不同谱仪的需求.系统在11.7T(500 MHz)NMR系统中进行了有效的锁场、匀场和梯度特性的测试,证明了该方案的可行性.