A 600V p-GaN Gate HEMT with Intrinsic Freewheeling Schottky-Diode in a GaN Power IC with Bootstrapped Driver and Sensors

摘要

A normally-off 600V GaN Power IC is presented, which combines a large-area power transistor with intrinsic freewheeling diode, a gate driver, and temperature and current sensors on-chip. A p-doped GaN gate layer is structured by selective GaN etching to achieve a threshold voltage of up to +1.8V. Wiring of the IC enables unipolar +5V or bipolar ±5V integrated gate drive. A single driver input with bootstrapped pre-driver logic inverter enables for both supply configurations a precise positive gate voltage of +5V for all logic and driver transistors, avoiding gate forward over-voltage degradation and threshold voltage related logic-level degradation. The current sensor uses an already existing source finger of large-area HEMT comb-structures as shunt. The integrated diode approximately halves the capacitance and area compared to discretely paralleled HEMTs and diodes, while at the same time the measured area-specific on-resistance of normally-off HEMTs with intrinsic diodes increases only negligibly compared to HEMTs without diodes. Clean 390V, 10A switching transitions and efficiencies up to 98.9% at 350V, 900W dc-dc conversion are shown.