随着低场永磁磁共振系统在食品检测、材料分析等领域的广泛应用，磁场均匀性对于获取高质量磁共振信号至关重要，而匀场放大器的性能直接决定了磁体的主动匀场效果．本文提出一种专用于低场永磁高分辨磁共振系统的高稳定性、低纹波匀场电流放大器设计方案．该方案采用高集成度的模块化设计，通过控制器局域网总线（Controller Area Network，CAN）通信实现通道扩展，并利用自偏置推挽电路实现了-1 A ~ +1 A的双极性电流输出，显著提高了输出线性度．为确保电流精度和稳定性，电流反馈检测端采用差分方式获取采样电阻两端电压差，有效抑制了共模噪声．该匀场电流放大器的输出电流线性回归系数R²优于0.999 999 9，48 h长期稳定度低至5.3 ppm（1 ppm=10^-6），实现了对匀场线圈电流的精确控制，具有良好的线性度和稳定性，可以满足低场永磁高分辨磁共振系统匀场线圈的驱动需求．

With the widespread use of low-field permanent magnet magnetic resonance (NMR) systems in fields such as food testing and material analysis, magnetic field uniformity is crucial for obtaining high-quality signals, and the performance of the shimming current amplifier directly determines the effectiveness of active shimming. This paper presents a specialized high-stability, low-ripple shimming current amplifier design for high-resolution, low-field permanent magnet NMR systems. The design employs a highly integrated modular architecture, supports multi-channel expansion via controller area network (CAN) communication, and utilizes a self-biased push-pull circuit to achieve bipolar current output from –1 A to +1 A, significantly improving output linearity. To ensure accuracy and stability, differential sensing is applied in the current feedback loop to effectively suppress common-mode noise. The amplifier demonstrates a linear regression coefficient R² > 0.999 999 9 and a 48‑hour long-term stability of 5.3 ppm (1 ppm=10^-6), enabling precise current control with excellent linearity and stability, thereby meeting the driving requirements of shim coils in high-resolution, low-field NMR systems.