Skip to main content
APEC 2026 Main banner

Resonant Converters

T25.5 - Design and Optimization of a 48V–1V Merged Buck–Boost LLC Converter for Vertical Power Delivery to Ultra-High-Current AI Processors

Thursday, March 26, 2026
9:40 AM - 10:00 AM CT
Location: 214A
This paper presents a merged buck-boost LLC (BBLLC) converter for 48V-to-1V conversion to enable vertical power delivery. In the proposed BBLLC architecture, the buck-boost stage and LLC resonant stage share a common bridge configuration, allowing their currents to commutate and mutually cancel during conduction intervals. This topological innovation not only reduces component count but also extends the zero-voltage switching (ZVS) range for all power switches. An innovative matrix transformer design is introduced to minimise magnetic flux density. The proposed merged BBLLC topology eliminates the right-half-plane (RHP) zero, thereby improving transient response characteristics. A 40V~60V to 0.8V-1.1V, 2.8 mm-thick, 300 A-output current module has been implemented and experimentally validated. The design achieves a peak efficiency of 90.3%, a full-load efficiency of 85.04% at 300 A/1.1 V, and a power density of 0.46 A/mm² near the load chip.