A High-Gain, High-Bandwidth, Bidirectional Discrete GaN-Based SyncFET dv/dt Sensor for MHz Power Converters

This paper presents a high-gain, high-bandwidth discrete dv/dt sensing and control architecture for megahertz gallium nitride (GaN)-based power converters. In conventional capacitor-only dv/dt sensing, the external sensing capacitor must remain smaller than the device’s reverse transfer capacitance to avoid loading effects, which inherently limits current gain and yields weak feedback signals. To overcome this constraint, the proposed approach introduces a synchronous GaN field-effect transistor (SyncFET) configured as a current amplifier, which boosts the weak capacitor current while preserving high-bandwidth operation. The amplified feedback current is processed by an active gate driver (AGD), realised with discrete GaN devices, that provides the necessary gain and bandwidth for precise dv/dt regulation. Together, the SyncFET and AGD form a dual-stage amplification system that enables effective dv/dt control without large sensor capacitance, high bus voltage or complex IC integration. Simulation and experimental validation in a 24 V, 10 MHz buck converter demonstrate that the combined SyncFET–AGD circuit reduces turn-on dv/dt from 15 V/ns to 10 V/ns while lowering switching loss by 16.7% compared with the conventional passive control. These results confirm that the proposed discrete gate-driving strategy mitigates the limitations of capacitor-only dv/dt sensing, offering dv/dt suppression and enhanced reliability in compact GaN-based converters.