3D LEGO-PoL: A 93.3% Efficient 48V-1.5V 450A Merged-Two-Stage Hybrid Switched-Capacitor Converter with 3D Vertical Coupled Inductors

This paper presents a merged-two-stage hybrid switched-capacitor point-of-load converter with 3D-embedded coupled inductors, vertical power delivery, and LEGO-PoL architecture. By merging a switched-capacitor circuit with a multiphase buck circuit, the 3D LEGO-PoL converter offers reduced device stress and minimized magnetic size, and enables soft switching, soft charging, voltage balancing, and current sharing. A prototype converter with 3D embedded coupled inductors is designed to deliver power vertically from the motherboard to microprocessors with minimized 2D area. A 675 W, 48 V to 1.5 V/450 A hybrid converter with a peak efficiency of 93.3%, full load efficiency of 87.2%, current density of 0.57 A/mm
²
, and power density of 688 W/in
³
was built and tested to verify the effectiveness of the hybrid converter architecture with 3D embedded coupled inductors and vertical power delivery.