Enhancement Mode GaN-FETs in Extreme Temperature Conditions, Part II: Dynamic Parasitic Parameters

Abstract

Parasitic components in eGaN-FETs impact the dynamic performance of switching stages. The capacitances seen, primarily on the output characteristics, of these devices are a main contributor towards switching losses and therefor converter efficiency. Additionally, the threshold voltage of the device has an impact towards the switching speed and therefore the efficiency of a power stage. This study shows the impact of extreme temperatures towards the parasitics that impact the switching behaviour of a power stage. A literature research is conducted exploring the various mechanisms and temperature dependancies, which are then related towards transient operations of eGaN-FETs. A device was chosen to perform measurements on output-, reverse transfer capacitance and threshold voltage while increasing temperature from 100°C op to 225°C. The presented results show a large impact of temperature in these parasisic elements that show that high temperature switch-mode power converters need additional design work to ensure switching performance and lifetime.