A 26-40 GHz GaN Doherty Power Amplifier with >20% PAE at 6-dBBack-Off Supporting Multi-Band 5G mm-Wave Applications

This paper presents a two-stage symmetrical wideband Doherty power amplifier (DPA) implemented on a 0.1 μm GaN HEMT technology. The DPA features a low-pass π impedance-inverting network, which incorporates the equivalent output capacitance of the transistors. Notably, the transistors in the final stage are supplied by a single DC voltage delivered through a short-circuited stub within the post-matching network. As a result, the IIN is designed with minimal frequency-dependent components, enabling broadband operation at peak power and at 6 dB BO. On-wafer measurements under continuous-wave excitation demonstrate that the DPA delivers a saturated output power of 32.4-33.7 dBm and a PAE of 22.5-29% over 26 to 40 GHz. At 6 dB OPBO, the DPA achieves a PAE of 20-23% from 26 to 40 GHz, corresponding to a fractional bandwidth of 42.4%. To the author’s best knowledge, this is the broadest circuit bandwidth reported to date for millimeter-wave DPAs.