A Monolithic GaN Power Stage with Common-Mode Transient Immunity and Negative Voltage Operation Design for High Frequency Power Converters

This paper presents a monolithic GaN power stage as a potential solution for high-frequency power conversion. The power stage incorporates fully-integrated GaN-based circuits and power switches, offering consideration for common mode transient immunity (CMTI) and negative voltage operation in GaN application scenarios. A buffered and shielded level shifting (BSLS) technique has been proposed as a means of optimizing speed, power consumption, and common-mode transient immunity (CMTI) capability in half-bridge signal transmission. An adaptive pull-down switching (APDS) circuit has been developed to tackle the issues of performance deterioration or even signal loss under freewheeling negative voltage conditions. To prevent shoot-through, a replica dead-time control (RDTC) strategy is implemented in the driver-stage circuit. With these key elements optimized, a monolithic GaN power stage based on 0.25 <tex-math notation="LaTeX">μ</tex-math> m 25 V enhanced mode GaN (eGaN) process proposed in this work can achieve an operating frequency of up to 25 MHz and a CMTI capability of 150 V/ns. Moreover, the design optimization combined with the inherent advantages of GaN devices help to achieve a gate driving signal delay of only 5.1 ns and a dynamic current of only 1.2 mA/MHz in the monolithic half-bridge power stage.