Switching Performance in a GaN Power Stage at Extreme Temperature Conditions

Exposure to an extreme ambient temperature leads to increased losses in a Gallium Nitride Field Effect Transistor (GaN-FET) when operating in a switch-mode power stage. The output capacitance of Gallium Nitride (GaN) devices is decreased at higher voltages but increased at higher temperatures. This paper highlights the effect of output capacitance in a half-bridge switching stage and offers analysis towards the switching losses. A power stage was built and tested with two timing optimizations: for room temperature and high temperature, respectively. Trading off dead time and the loss mechanisms involved, a loss reduction of 16.1% was achieved. This loss reduction was further improved to 26.1 % after thorough investigation of the switch node transient responses.