A Continuous-Mode Harmonic-Tuning Ku-Band GaN MMIC Doherty Power Amplifier with an 18.7 % Fractional Bandwidth

This paper presents a Ku-band continuous-mode harmonic-tuning Doherty power amplifier (CMHT-DPA) using 0.12-μm GaN HEMT MMIC technology. Detailed design considerations of the broadband impedance-inverting network (IIN) and phase compensation network (PCN) are discussed and implemented, together with the continuous-mode loading (CML) for achieving wideband operation while maintaining high output power back-off (OBO) efficiency. Measured results show that the proposed DPA exhibits a Psat of 38.7 dBm, with a peak PAE of 31.3 % and a PAE of 28.2 % at 6-dB OBO. The small-signal gain is up to 17.9 dB within the 3-dB bandwidth from 13.6 to 16.4 GHz, corresponding to an 18.7 % fractional bandwidth. Compared to previously published GaN DPAs in a similar frequency range, the proposed DPA achieves the highest efficiency at both saturation and 6-dB OBO and the largest fractional bandwidth, with the obtained FoMs among the best.