Power integration is essential for the fully utilization of advanced GaN devices in power conversion applications due to the reduced parasitic inductance, low on-state resistance, and high-temperature operation. This paper presents a GaN-based monolithic integration design with optimized gate drivers for high-temperature DC-DC converters. Four different gate drivers are experimentally evaluated for integration with boost converters based on enhancement (E)-mode AlGaN/GaN metal-insulator-semiconductor heterojunction-field-effect-transistors (MIS-HFETs). The optimized gate driver, consisting of DCFL (Direct-Coupled FET Logic) inverters and a buffer amplifier, can operate over a wide temperature range (from 25 °C to 250 °C). Furthermore, a 100 kHz, 5 V/11 V (V IN /V OUT ) boost converter prototype with the proposed monolithic integration design was built and found to operate successfully under high temperatures (HTs) up to 250 °C. These results validate the advantages of GaN-based monolithic integration techniques in achieving HT, high power density, and high efficiency power converters.

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This paper presents a GaN based synchronous buck DC-DC converter, which monolithically integrates gate drivers and a half-bridge power stage in a 3-µm enhancement-mode (E-mode) GaN-on-Si process. The fabricated synchronous converter with integrated gate drivers is based on E-mode GaN MIS-HFETs (metal-insulator-semiconductor heterojunction-field-effect-transistors), which have a large gate swing of 10 V due to the insertion of 20 nm high-k gate insulator Al 2 O 3 . At 100 kHz, the proposed DC-DC integrated circuits (ICs) exhibit good thermal stability at high temperatures up to 250 • C for 25 V down conversion. Furthermore, four different designs (asynchronous and synchronous) including converters with external drivers were systematically evaluated at different input voltages and duty cycles, the GaN-based DC-DC converters with integrated gate drivers exhibit small voltage overshoots and oscillations due to reduced parasitic inductance and chip size. These results validate the advantages of monolithic, lateral integration of half-bridge GaN ICs with gate drivers for high temperature power converters.INDEX TERMS GaN integration circuits (ICs), high temperature operations, integrated gate drivers, synchronous and asynchronous dc-dc buck converters.