Characterization and optimization of active negative voltage driving circuit for CoolGaN HEMTs in a phase-leg configuration

Abstract

The high switching speed of GaN HEMT will cause serious crosstalk in the phase-leg configuration. The negative turn-off driving voltage is usually recommended to avoid the parasitic shoot-through. However, the adoption of negative turn-off voltage will increase the reverse conduction loss during the dead time, which brings impact on the efficiency of GaN-based converter, and the selection of negative turn-off voltage is also limited by the maximum negative voltage capability of gate–source. Taking CoolGaN HEMT drive circuit as the research object, the crosstalk suppression method is analyzed in detail. Then, an active negative voltage driving circuit is proposed. The novel driving circuit realizes the negative-voltage and zero-voltage combined shutdown mode, which can not only meet the requirements of crosstalk suppression, but also minimize the reverse conduction loss of GaN device. The influence of crucial parameters in active negative voltage driving circuit on the reliability and power loss of bridge-arm circuit is explored, and the optimization design method of each parameter is obtained, so as to provide theoretical and design guidance for high efficiency driving circuit with high reliability.

Keywords

• CoolGaN HEMT
• Active negative voltage
• Crosstalk suppression
• Parameter optimization