Single-tone and two-tone time-domain large signal characterization of GaN HFETs operated in class A

GaN HFET's have been analyzed under single-tone and two-tone excitation, using an error corrected time domain measurement system. This approach yields a better understanding of the device's non-linear behavior, particularly with respect to intermodulation distortion. It has been found that under single-tone excitation, the AlGaN/GaN HFET produced fundamental and third harmonic output with virtually constant phase (no AM-PM), even when operated well into compression. This would imply that the device should exhibit symmetric intermodulation products under two-tone excitation, and this was experimentally found to be the case. These results further indicates that AlGaN/GaN HFET technology has the potential for use not only in high power and high efficiency, but also high linearity applications.