A 400-V Half Bridge Gate Driver for Normally-Off GaN HEMTs With Effective Dv/Dt Control and High Dv/Dt Immunity

This article presents two techniques to address the reliability issues caused by dv/dt under fast switching conditions of gallium nitride high electron mobility transistors. The first technique called active overdrive voltage control is proposed to adjust the gate driving strength according to the rising speed of the switching node (dv/dt) adaptively and, thus, decrease the dv/dt without increasing too much switching loss. The second technique is three-branch high-voltage level shifter (TBLS), which can improve the dv/dt immunity without compromising the signal transmission speed. The common mode current caused by dv/dt can be copied and then compensated by a transient current provided by the auxiliary branch. Combining the above techniques, a 400 V half bridge gate driver IC is fabricated by silicon-on-insulator BCD process. Compared with the gate driver IC utilizing the conventional open-loop output stage, the proposed gate driver IC reduces the turn-on switching loss by 16.2% for the same level of peak dv/dt at 400 V 10 A application. In addition, the proposed TBLS can achieve the dv/dt immunity up to 100 V/ns meanwhile the propagation delay less than 14 ns, enabling megahertz operation frequency.