Balun with one inductor and three capacitors for MRI RF coils

Abstract

Background

High-density and flexible RF coils in MRI systems have greatly improved patient comfort and enhanced the signal-to-noise ratio (SNR) by better conforming to anatomical shapes and reducing weight. However, the feed boards in flexible coils often occupy large space and require many components, which can limit coil flexibility and integration.

Purpose

To minimize the footprint of the feed board and reduce the number of components while maintaining effective common-mode suppression, this study introduces a compact one-inductor-three-capacitor (LCCC) lumped-element balun design.

Methods

The proposed LCCC balun consists of three capacitors and one inductor. Theoretical analysis based on Kirchhoff’s circuit laws was used to determine the optimal component values, and numerical simulations were conducted to verify the design performance. Prototypes for both 3 T and 7 T MRI were fabricated and experimentally evaluated.

Results

The experimental results demonstrated negligible insertion loss and effective common-mode current suppression across the operating frequencies. The compact design enables easy integration into flexible RF coil arrays. Furthermore, this study explores the potential for dual-tuned applications and alternative topologies, highlighting the versatility of the LCCC balun in advanced MRI RF technologies.

Conclusion

The LCCC lumped-element balun offers a simple, compact, and versatile solution for flexible MRI RF coils. Its small footprint and strong performance make it a promising candidate for next-generation high-density and dual-tuned RF coil arrays.