Frequency Dispersion of Drain Conductance in AlGaN/GaN HEMT Evaluated Using Sinusoidal Wave Signal Input

We firstly demonstrate dynamic change in a drain conductance of an AlGaN/GaN HEMT from DC to high frequency using sinusoidal wave input signal from a network analyzer which can sweep from hertz to giga hertz. Prior to measurements, a bias-T which is adaptable at a frequency of hertz to mega hertz has been developed. S-parameter measurements sweeping from 5 Hz to 3 GHz reveals that the magnitude of S22 significantly decreases at a hertz to mega hertz frequency range although the phase of S22 is negligibly stable. Also, it is found that the drain conductance evaluated from drain I-V characteristics and that extracted from S- parameters at 100 Hz are comparable and that a drain conductance from mega hertz to hundreds mega hertz is stable, indicating that some trapping or de-trapping effects occur at this frequency range.