High-Power Asymmetrical Three-Way GaN Doherty Power Amplifier at C-Band Frequencies

In this paper the design and realization of an asymmetrical three-way (1:1:1) GaN Doherty power amplifier (DPA) operating at a center frequency of 5.4 GHz is presented. The DPA is constructed from three packaged power bars, each consisting of four GaN HEMT cells (8 fingers, 300 μm unit gate width) in 0.25 μm gate length. Performance of the realized DPA prototype is analyzed under pulsed-RF excitation ($20\mu \mathrm{s}$ pulse width, 10 % duty cycle) at 40 V DC drain supply voltage. The measurement results yield 48.5 dBm maximum output power, with a maximum PAE of 46 %. At 6 dB output power back-off (OPBO) the DPA demonstrates 40 % PAE whereas 35 % PAE is achieved at 9 dB OPBO.