Systematic procedure for load-pull X-parameters measurements for high-efficiency GaN HEMT PA design

In this paper, the X-parameters load-pull measurements for high-efficiency multi-band power amplifier design are described. A commercially available 10 W Cree CGH40010F GaN HEMT is used for characterization at three harmonics of the typical telecommunication frequencies: 1.8 GHz, 2.1 GHz, 2.45 GHz, and 2.7 GHz. The measurement setup and procedure are described. Special attention is being paid to the calibration methods in order to ensure the validity of the X-parameters. Using load-dependent X-parameters the optimal large signal operating point for each fundamental frequency was found. For all the bands output power over 10 W and power-added efficiency over 70 % were obtained.