Theoretical Analysis and Design of a 22--44-GHz Quasi-Balanced Doherty Power Amplifier With Enhanced Wideband PAE Performance and 3:1 VSWR Tolerance in 28-nm FD-SOI CMOS

This article presents a broadband 5G power amplifier (PA) robust to voltage standing wave ratio (VSWR) variations and featuring high efficiency up to deep power back-off (PBO) in 28-nm FD-SOI CMOS technology. The proposed architecture, based on a quasi-balanced structure and an inductive load, offers an alternative to the conventional Doherty PA to maintain its$\text {PAE}_{\text {6dBPBO}}$enhancement up to 3:1 VSWR over a wide bandwidth. A detailed theoretical analysis demonstrates the improved broadband performance that can be achieved with this architecture, as well as its robustness to VSWR variations. Indeed, the degradation of its$\text {PAE}_{\text {6dBPBO}}$is kept below 7% between 22 and 44GHz. The circuit achieves 24%$\text {PAE}_{\text {6dBPBO}}$and 16%$\text {PAE}_{9.\text {7dBPBO}}$at 28GHz, while guaranteeing linearity in line with the 5G standard. The PA occupies a surface area of 0.82 mm2.