Low-cost and Compact eGaN Gradient Power Amplifier Operation at High Frequency: Reduced Noise Switch-mode Power Conversion

Motivation: Highly mobile low-field imaging systems are often burdened by large gradient amplifiers, which must be carefully designed to avoid introducing noise. Goal(s): Reduce the size and cost of the gradient power amplifier without introducing significant noise. Approach: Leveraging a previous amplifier design with relatively new power transistor technologies, design a switched-mode gradient drive system that is highly efficient and low noise by optimizing the switching frequency. Results: This low-cost and compact gradient power amplifier and control system is shown to avoid noise issues common to switch-mode power amplifiers by operating at high frequencies. Impact: This gradient amplifier for low-field MRI employs a eGaN-transistor-based design to shrink size and cost while suppressing noise by switching at an optimized frequency, near to but not the Larmor frequency. These improvements will help improve MRI accessibility and mobility.