A 0.3dB-NF SiGe LNA Array for 10.5T Multi-Channel MRI Receivers

This paper presents an on-chip LNA array at 447MHz for 10.5T multi-channel MR receive arrays. First, we develop a theoretical foundation for minimizing bipolar amplifier noise figure, and design an LNA based on this approach. Additionally, we consider several implementation factors including coupling between channels and magnetic-field robustness. A preamplifier array based on this concept is then fabricated using the GF 8XP 130nm SiGe process. The total area of the 4-element array is 2.2mm × 1.2mm with each channel consuming 20mW. Measurements show an excellent noise figure of 0.3dB, a gain of 28dB across 410–510MHz, and more than 29dB isolation making this array a viable replacement for existing bulky off-the-shelf solutions. The theoretical calculations, design kit simulations and measurements results show good agreement. This chip opens the door for integrated receiver systems for next generation high-channel-count MR arrays.