Pulsed <i>I</i>/<i>V</i> and <i>S</i>-parameters measurement system for isodynamic characterization of power GaN HEMT transistors

Abstract

This article presents a system capable of performing isodynamic I/V and S-parameter measurements. It is focused on the necessary characterization signals, laboratory equipment, and pulser (power head). Proper biasing waveforms are developed and used to extract accurate nonlinear measurements that take into account the frequency dispersive phenomena, namely, the drain lag and temperature rise observed in GaN HEMTs. The pulser can drive high power devices (120 V and 45 A) for very fast and accurate pulses (widths between 300 and 800 ns). As validation, a commercial 15 W GaN device (CGH27015P) from Wolfspeed was characterized using this setup. The consistency between the obtained pulsed I/V curves and others obtained by the integration of the small signal transcondutance (gm) and output conductance (gds) proves that the presented system is capable of performing isodynamic characterization of power transistors.