Active harmonic source-/load-pull measurements of AlGaN/GaN HEMTs at X-band frequencies

Active harmonic loadpull measurements investigation for a 1-mm AlGaN/GaN HEMT power transistor at X-Band frequencies are in this paper reported. The paper highlights the transistor performances in terms of maximum PAE, P(out) and Gain achieved at 8.7 GHz together with the application of a systematic source-/load-pull measurement procedure including wafer-mapping capability. The measurements were carried out using an active harmonic loadpull test sytem with four control loops. In particular, fundamental and second harmonic "loads" as well as second harmonic "source" terminations have been properly varied and optimized. The 1-mm GaN power device delivered very high efficiency of DE=71.2 % and PAE=66.1 % together with high P(out) and power gain of 35 dBm (3.2 W) and 11.5 dB, respectively.