Fully Integrated Galvanic Isolation Interface in GaN Technology

This paper presents for the first time a fully integrated galvanic isolation interface in a GaN technology. It is based on planar micro-antennas and chip-to-chip communication with an on-off keying-modulated RF carrier. This approach can achieve high isolation rating and high common-mode transient immunity by properly setting the distance between chips. The interface provides the isolation channel for a main driver/power switch and the one for the control feedback of the dc-dc converter providing the isolated power supply. Driver and power control channels adopt an RF carrier of 2 GHz and 1.2 GHz, which are modulated by a pulse width modulated signal of 2 MHz and 0.5 MHz, respectively. The interface includes a continuously operating offset compensation approach, which overcomes not only the strong variations due to the large process tolerances of the GaN technology, but also offset drifts due to temperature variations. An accurate pulse width modulated signal with a large duty cycle variation in both channels was achieved. The isolation interface adopts a 6-V power supply, which delivers a quiescent current of 6.3 mA and 7.5 mA to the driver and power control channels, respectively, assuming a signal with a duty cycle of 50%.