A Compact 28/39GHz Dual-Band Concurrent/Band-Switching LNA for 5G Multi-Band Multi-Stream Applications

This paper presents a 28/39 GHz multi-mode low noise amplifier (LNA) for 5G flexible dual-band beamforming MIMO applications. In the proposed LNA, its input stage leverages a compact three-winding transformer coupling technique to achieve wideband power gain and low noise figure (NF) in both 28/39 GHz bands. With two parallel gm-boosting reconfigurable common-gate amplifiers, the band-multiplexer block is realized, and the wideband signals could be split into two signal paths independently to support concurrent/band-switching modes. Based on the independent band splitting feature, the LNA output stages could be customized with the gm-boosting active gain cell and narrow-band passive matching network, achieving both enhanced power gain and out-of-band rejection. Fabricated in a 65-nm CMOS process, the proposed LNA occupies a compact core size of only 0.1 mm². With measurements, the LNA achieves 26.3/25.5 dB peak gain, 3.6/3.8 dB minimum NF, -18.5/-16.4 dBm IIP3 in the 28/39 GHz band-switching mode, and 22.9/23 dB peak gain, 4.97/4.9 dB minimum NF, -14.7/-12.4 dBm IIP₃ in the 28/39 GHz concurrent mode.