Gallium Nitride FETs Research Articles

Capacitor-Less Gate Drive Circuit Capable of High-Efficiency Operation for Non-Insulating-Gate GaN FETs

Recently, Gallium Nitride (GaN) power devices have become very attractive because of their high power density. GaN FETs, however, differ from MOSFETs, and it is possible that GaN-based power electronics circuits show lower efficiency than Si-based circuits because of their unique characteristics. A capacitor-less gate drive circuit is proposed as a solution. This paper shows the effectiveness of a capacitor-less gate circuit in terms of gate drive loss, reverse conduction loss, and recovery loss, and compares it with capacitor-type gate drive circuits for GaN FETs. Drive loss analysis of an inverted gate drive circuit showing the lowest losses among capacitor-type gate drive circuits and a capacitor-less gate drive circuit was made to examine the differences between them. The results show that higher efficiency operation is obtained by applying a capacitor-less gate drive circuit to simple test circuits.

ANALYSIS OF LOW FREQUENCY DRAIN CURRENT NOISE IN AlGaN/GaN HEMTS ON Si SUBSTRATE

This paper deals with the analysis of the low frequency drain current noise in gallium nitride FET on silicon substrate. The drain current noise is compared for devices with gate length of 1.5μm and 3.5μm. We discuss two types of noise mechanisms both used as a diagnostic tool: generation-recombination noise and 1/f noise. Measurements in saturation regime have revealed a g-r noise mechanism correlated with the activation of discrete traps. The analysis of the normalized drain current spectral density vs. the normalized gate voltage Vgn=(Vg-Vt)/|Vt| has been studied. In particular, we have pointed out that the evolution of the 1/f noise level strongly depends on the evolution of the gate leakage current. On the basis of the 1/f normalized noise, i.e. the αH/N parameter, GaN HEMT on silicon have demonstrated as low LF noise as GaAs based transistors.