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 (DPA) 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, Cout, of the transistors while implementing the Doherty combining network with a simplicity close to the original concept, 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 × 4 mm die with a power density of 0.47 W/mm².