AlScN-Based SAW Magnetic Field Sensor for Isolated Closed-Loop Hysteretic Current Control of Switched-Mode Power Converters

This letter uses a surface acoustic wave magnetic field sensor for measurement and closed-loop current control of the inductor in GaN-based dc-dc power converter. The is based on aluminium scandium nitride thin films with relatively high Sc concentration 32% fabricated low-cost 8-in silicon substrate, magnetostrictive FeCoSiB film top SAW delay line. device has dc bidirectional capability (derived from flux density around trace) operated electrically isolated above trace. With permanent magnets as bias, setup usable range ±5 A. A phase detector IC measures shift between 296 MHz, 19 dBm input, 35 dB attenuated output signal line sensor. active area distance 2.5 mm In 1.2 mT sensitivity 18.28°/mT bipolar up to enhanced by an analog filter compensate over 1 µs readout circuit. Finally, used input hysteretic loop. operation demonstrated using 48 V half-bridge converter 16 kHz triangular current.