A Highly Efficient 18-40 GHz Linear Power Amplifier in 40-nm GaN for mm-Wave 5G

A medium-power, highly-efficient broadband linear power amplifier (PA) is designed in a 40-nm GaN technology that covers the key 5G FR2 band of 24-40 GHz. Load-pull simulations suggest better device broadband performance and peak power-added-efficiency (PAE) around $V_{\text {DD}} =4$ -6 V. Measurement data corroborates the simulations and this PA achieves a small-signal 3-dB bandwidth (BW) of 18.0-40.3 GHz, with max. PAE/ $P_{\text {SAT}}$ of 42.1%/18.6 dBm at 28 GHz, and 26.0%/17.2 dBm at 38 GHz at $V_{\text {DD}} = 4$ V. When tested with a 9 MHz $\times \,\, 100$ MHz 256-quadratic-amplitude modulation (QAM) 5G new radio (NR) signal, it achieves an adjacent-channel-leakage-ratio (ACLR) of -27 dBc with $P_{\text {OUT, AVG}}$ /PAE of 11.3 dBm/13.9% at 28 GHz. When compared with state-of-the-art broadband PAs, it achieves the best $S_{21}~3$ -dB BW with excellent peak PAE and linearity. This work also reports the best PAE for broadband medium-power millimeter-wave GaN PA at $P_{\text {SAT}}~\sim 20$ dBm.