A High-Efficiency E-Band GaN Doherty Power Amplifier with 35.7 dBm Output Power and 22.8%/16.8% Peak/6-dB Back-Off Efficiency

This paper presents the design of a high-efficiency and high-power E-band (69 – 76 GHz) Doherty power amplifier (DPA) fabricated on a IAF 100-nm gate-length GaN-on-SiC HEMT technology. The DPA adopts an asymmetrical five-stage topology, with the final stage employing a low-loss distributed power combiner that integrates four transistors in the Main and Auxiliary branches. Under continuous-wave (CW) excitation, the DPA delivers a saturated output power (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text{SAT}}$</tex>) of 35.7 dBm associated with a power-added-efficiency (PAE) of 22.5%, at 69 GHz. At 6-dB output power back-off (OBO), the DPA exhibits a PAE of 16.8%. To the authors' knowledge, this is the first high-power (beyond 30 dBm) GaN-DPA demonstrator at E-band.