Large signal frequency dispersion effects in indium phosphide HEMTs

The work uses RF gain compression behaviour to investigate the existence of large signal frequency dispersion in lattice matched and pseudomorphic indium phosphide HEMTs. A comparison of DC model parameters and parameters obtained by optimising the model to fit to measured gain compression of a Class AB amplifier suggests that the RF knee voltage is larger than that observed in DC measurements. It is believed that this effect is of potential concern to the designers of indium phosphide HEMT power amplifiers, particularly those using low voltage processes.