Design and Experimental Characterization of an Asymmetric GaN MMIC Doherty Power Amplifier for Ka-Band Transmitters

This paper presents the design and experimental characterization of an asymmetric Ka-Band Doherty power amplifier based on a 0.12 µm GaN MMIC process. The design relies on the identification of an optimum load modulation trajectory on the load-pull contours of the main PA. The fabricated prototype shows a peak output power of 34 dBm and an 8-dB back-off power added efficiency of 17% at 28.3 GHz. When tested with a 100 MHz channel 5G signal, the amplifier demonstrates good intrinsic linearity and it is linearizable using digital predistortion.