GaN FET with integrated current sense without supply

This paper proposes an advanced GaN FET in PDFN package with integrated current sensing (CS) circuity requiring NO external supply. Traditionally, the switch current is sensed by external shunt resistor or current transformer in series with main FET for peak/valley current mode control or over-current-protection in power electronics applications such as flyback or PFC. Integrating the CS in GaN switches can reduce sense resistor loss leading to improved efficiency, better thermal dissipation and also can optimize the gate loop layout resulting in cleaner Vgs of GaN FET by allowing direct connection of source and ground net. The proposed GaN FET chip including CS functionality has been experimentally verified by double pulse and boost test circuit in both DCM and CCM modes. The advantages in the system application have been verified by a 65W adapter design.