Modeling and limitations of AlGaN/GaN HFETs

Field effect transistors based upon the AlGaN/GaN system often demonstrate current slump and premature saturation of the gain, accompanied by degradation of the RF output power and power-added efficiency. It is shown that source resistance modulation under high current injection conditions can produce premature saturation effects consistent with experimental data. Elimination of the effect will require design modifications that increase the threshold for space-charge effects to become significant.