A Universal Photodiode-Based Optical Gate Driver for GaN Power Devices

Optically controlled power devices hold promise for achieving minimal triggering delay, simplified control for device stacking, and high electromagnetic interference (EMI) immunity. Although gallium nitride (GaN) devices are rapidly advancing power electronics applications, optically controlled high-voltage switching has rarely been reported in GaN. This work addresses this gap by presenting a universal, optically controlled gate driver based on two photodiodes (PDs) in a totem-pole structure capable of switching GaN power devices with fast speed and low optical power. The two reverse-biased PDs are controlled by complementary optical signals to provide gate current, emulating a current-source gate driver. The proposed driver is demonstrated on both voltage- and current-driven GaN transistors, including a 650 V GaN high-electron-mobility transistor (HEMT) and a 1200 V vertical GaN junction-gate field-effect transistor (JFET). The GaN HEMT achieves some of the fastest switching speeds and lowest required optical powers reported for optically controlled power devices. For the current-driven GaN JFET, the PD’s intrinsic properties provide both transient and steady-state gate current, simplifying the driving circuitry and reducing driver losses. An analytical model is further developed to describe the switching dynamics of both devices under PD-based optical control. These results reveal the potential of PD-based optical gate driving schemes for advancing GaN power electronics.