Integration of Miller Circuit with RC Network for Negative-Voltage Gate Drive of GaN Devices

The crosstalk issue is one of the primary factors that increase the loss of GaN HEMTs and compromise the switching speed. In practical applications, the GaN gate drivers are based on either RC circuit or Miller circuit. However, the RC circuit lacks the crosstalk absorption path that makes it difficult to suppress the crosstalk voltage. On the contrary, although the Miller circuit has the absorption path, the low-impedance loop results in the reduction of switching speed. To inherit the advantages of the two common used methods and avoid their shortcomings, in this paper, a method to integrate the passive Miller clamp circuit together with the RC circuit is proposed. The proposed integration is achieved by an RC delay circuit with a passive controlled PMOS. The RC delay circuit with the PMOS adjusts the activation time of the Miller clamp circuit, therefore, the proposed drive circuit could suppress the crosstalk without compromising switching speed. The simulation and experimental are conducted under various operating conditions to verify the effectiveness of the proposed circuit. The experimental results demonstrate that under 300 V DC voltage condition, the proposed circuit achieves a 19.36% reduction in the positive crosstalk voltage, a 26.21% reduction in the negative crosstalk voltage, and a 2.41% decrease in the reverse conduction loss.