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 mu m unit gate width) in 0.25 mu m gate length. Performance of the realized DPA prototype is analyzed under pulsed-RF excitation (20 mu 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.