This paper presents a 28nm FD-SOI CMOS 24-31GHz broadband PA robust to 3:1 VSWR variations and exhibiting high linearity and efficiency up to deep power back-off. The circuit architecture proposes an energy efficient alternative to the Doherty PA enabling a continuous operation mode between symmetrical and asymmetrical modes. The PA exhibits 37% and 26% peak-6dB PBO PAE at 26GHz for asymmetrical/symmetrical operation, respectively. The measured results show compliance to the 5G NR and 64-QAM modulation schemes. The VSWR robustness is obtained thanks to the usage of hybrid couplers enabled in this topology. The PA core area occupies 0.90mm².