Chinese Journal of Magnetic Resonance >
A High-stability Shimming Current Amplifier Design for Low-field Permanent Magnet NMR Systems
Received date: 2026-02-07
Online published: 2026-08-11
The widespread application of low-field permanent magnet NMR systems in areas such as food testing and material analysis places higher demands on the quality of NMR signals. 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.
LU Xingyun , YAO Shouquan , XU Juncheng , JIANG Yu . A High-stability Shimming Current Amplifier Design for Low-field Permanent Magnet NMR Systems[J]. Chinese Journal of Magnetic Resonance, 2026 , 43(3) : 268 -278 . DOI: 10.11938/cjmr20263206
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