Analysis of dispersion in intermodulation distortion in GaN HEMT devices

The considerable variation in intermodulation across wide bandwidths due to trapping and self-heating mechanisms are considered here as a dispersion of linearity that is bias dependent. This is of interest to designers because the dispersion gives intermodulation a strong dependence on center and spacing of test frequencies, which requires an interpretation of intermodulation measurements and specifications across the whole signal bandwidth. Detailed intermodulation distortion and pulse measurements were performed for this study. New self-heating and trapping models are used to characterize intermodulation distortion and pulse measurements.