A Low-cost, Small-footprint Gradient Amplifier for Low Field MRI Based on GaN FETs

Motivation: The gradient system can be the most expensive part of a low field MRI system with minimal construction costs. Current solutions have linear amplifiers which may not reach power requirements, requiring pricey off-the-shelf amplifiers. Goal(s): Reduce the cost of the gradient drivers by taking amplifier efficiency into consideration to enable better low field MRI system creations. Approach: Uses an amplifier topology more commonly used at higher power, an H-bridge, but a high switching frequency reduces filtering requirements. A modular design eases construction. Results: The amplifier we created attains an increased efficiency, a smaller size, and a lower cost to attain useful power. Impact: Gradient drivers can dominate the overall cost of low-field MRI scanners. Our amplifier costs under 80USD and is capable of a 120V 15A DC output with a bandwidth of 150kHz. It contributes to cost reduction of gradient drivers significantly.