A 400V Monolithic GaN-on-SOI Half-Bridge with On-Chip Accurate Current Detection for Isolated Power Converters

This paper presents a high-precision, low-loss, fully on-chip current detection scheme for a monolithic integrated GaN half-bridge in high-voltage isolated converters. The proposed design integrates power switches, gate drivers, an on-chip current sensor and a relative-negative voltage supply using a GaN-on-SOI process, addressing challenges posed by parasitic inductance and signal transmission delays. To enhance detection accuracy and minimize power loss, a sense-HEMT scheme with an amplifier clamping loop featuring auto-zeroing is utilized. The simulation results show that the current detection accuracy of the proposed design surpasses 96%, and is sucessfully demostrated in an active clamp flyback converter. Additionally, a multi-stage self-cycling and bootstrap driver is proposed, characterized by driving delays of ton=6.5 ns and toff=6.3 ns, and proving a rail-to-rail driving voltage.