基于FPGA与DDS的磁共振成像射频脉冲发生器

摘要

设计了一种基于现场可编程门阵列（FPGA）与直接数字频率合成（DDS）的磁共振成像（MRI）射频脉冲发生器，采用FPGA实现DDS，并内置软脉冲波形双端口随机存取存储器（RAM）、乘法器以及相关的控制逻辑.实现了较高的技术指标，其中频率、相位与幅度分辨率分别为32 bits、16 bits与16 bits，软脉冲波形的时间精度可达0.1ms. FPGA提供了一个可编程的接口，便于序列控制器对其进行控制，以输出射频脉冲. MRI实验结果证明了该设计的可行性.%A radio frequency (RF) pulse generator for magnetic resonance imaging (MRI) was designed based on field programmable gate array (FPGA) and direct digital synthesis (DDS). The generator utilizes FPGA to achieve DDS and embed soft pulse waveform (RAM), multiplier and related control logic. The RF generator showed high technical specifications, with frequency, phase and amplitude resolution up to 32 bits, 16 bits and 16 bits, respectively. Time precision of the soft pulse waveform reached 0.1ms.FPGA provided a programmable interface, facilitating the control from sequence controller and generation of RF pulses. The feasibility of the design was demonstrated with imaging experiments.