Abstract

Average rf gate and drain currents can be used to determine gain compression mechanisms for PHEMTs with different pinch-off voltages. Knee voltage, pinch-off voltage, breakdown voltage and Imax clip output I-V waveform of a PHEMT and cause gain compression. We found that there is a distinct signature in average rf gate and drain currents to characterize each gain compression mechanism in PHEMTs. A PHEMT with low pinch-off voltage behaves the same in rf gate and drain currents as a PHEMT with high pinch-off voltage in pinch-off voltage, knee voltage and breakdown voltage gain compression mechanisms, but behaves differently in Imax gain compression mechanisms.