A Large-Signal Characterization Method for Dynamic Gate Capacitances of p-GaN HEMTs

Abstract

Small-signal C–V characterization is widely used to extract parameters in simulation models of gallium nitride (GaN) high-electron-mobility transistors (HEMTs). However, it fails to reproduce the gate charge behavior under dynamically varying bias conditions during the switching transient, resulting in significant inaccuracies in circuit simulations. This work presents a large-signal characterization method that captures the dynamic gate-charging behavior of Schottky-gate p-GaN HEMTs. Switching tests are conducted under two distinct bias conditions to extract the gate-source charge profile, which is subsequently subtracted from the total gate charge to obtain the gate-drain charge profile. The extracted C–V characteristics are compared with the industry-standard SPICE model and also with the conventional small-signal measurements, clearly demonstrating the necessity of large-signal characterization for accurate modeling of GaN HEMT gate capacitances.