Highly-Efficient Switched-Mode Radio Frequency Power Amplifier for Magnetic Resonance

Motivation: Existing RF amplifiers for MR are predominantly implemented using linear topologies, which suffer from poor efficiency and require bulky cooling systems. Goal(s): Our goal is to significantly reduce the energy consumption, cost and size of RF systems used in MR by developing a highly efficient and compact RF amplifier with only passive cooling. Approach: We develop a broadband switched-mode amplifier capable of generating chirped RF pulses with the same amplitude spectrum as conventional sinc pulses. Results: A compact prototype is demonstrated with a 2 MHz bandwidth centered around 64 MHz. Experimental measurements show an efficiency of 85% when generating 150W chirped RF pulses. Impact: The proposed technology significantly improves the efficiency of RF power amplifiers, contributing to more sustainable MR systems. It also provides advantages by reducing both the cost and size of hardware, potentially increasing the accessibility and portability of MR systems.