AlGaN/GaN HFET amplifier performance and limitations

Wide bandgap semiconductor field-effect transistors based upon the AlGaN/GaN heterostructure often demonstrate premature saturation and degradation of the RF output power, power-added efficiency, and gain as the device is driven into saturation. The effect is generally accompanied by ´current slump´, where the dc current decreases with increasing RF drive. It is demonstrated that charge non-confinement in the 2DEG under large-signal conditions can produce source resistance modulation that degrades RF performance consistent with experimental data.