A 28/39 GHz Concurrent/Band-Switching LNA With Three-Winding Transformer and Common-Gate-Based Multiplexer Supporting Multistream and Multiband 5G FR2 Communication

In this article, a 28/39 GHz band reconfigurable low noise amplifier (LNA) is designed with concurrent and band-switching operation modes, aiming to flexibly support multiband and multistream 5G FR2 communication. For facilitating integration with a multiband antenna, the LNA first-stage leverages an ultra-compact three-winding transformer (TF) coupling technique, enabling relatively high power gain and low noise figure (NF) across both 28 and 39 GHz bands. Moreover, we adopt a $\pi $ -model of the three-winding transformer to decompose the complex optimization problem into passive network matching and active cell improvement, bringing in more intuitive and rigorous design insights and guidance. In the following stage, a band-multiplexer is implemented using two switchable parallel $g_{m}$ -boosting common-gate (CG) amplifiers, which separate the wideband signals into frequency division signal paths, thereby supporting concurrent and band-switching modes. Moreover, the LNA output stages in separated paths can be independently optimized, meeting each sub-band specific requirements. Fabricated in a 65-nm CMOS process, the LNA occupies a compact core area of 0.1 mm2. In the band-switching mode, it achieves 26.3/25.5 dB peak gain, 3-dB bandwidth of 21.8–30.3 GHz/32.6–45.1 GHz, 3.6/3.8 dB minimum NF, −18.5/−16.4 dBm third-order intercept point (IIP3), more than 10.3/15.7 dB out-of-band rejection for 28/39 GHz band, respectively, and consumes 19.2 mW with a 1.2 V power supply. In the concurrent mode, the LNA achieves 22.9/23 dB peak gain, 4.97/4.9 dB minimum NF, −14.7/−12.4 dBm IIP3, more than 10/11 dB out-of-band rejection for 28/39 GHz band, and a power consumption of 38.4 mW.