Ku-Band Doherty Power Amplifier with Differential Power Combiner in an Advanced GaN-on-Si HEMT Technology for 6G FR3 Applications

This paper presents a fully monolithic Ku-band Doherty power amplifier employing differential power combiner cells as main and auxiliary amplifier in Infineon’s RF GaN-on-Si HEMT MMIC technology. The differential power combiner absorbs the intrinsic output capacitance, $C_{out}$, of the transistors while implementing the Doherty combining network with a simplicity matching that of the classical Doherty theorem, which eases high-frequency design and integration. The DPA is characterized under pulsed-RF conditions and achieves a maximum small-signal gain of 9.4~dB at 15.1~GHz, a saturated output power of about 37.7~--~38.7~dBm with a peak PAE of 28.7~--~32.3~\%, and a 6-dB OBO PAE of 22.5~--~25~\% over 14.3~--~15.3~GHz, corresponding to a 6.7\% fractional bandwidth, in 4~mm~$\times$~4~mm die with a power density of approximately 0.47~W/mm$^{2}$.