A Compact 48-V-to-Sub-1-V Switching Bus Converter with 4.7-mm Height for Processor Vertical Power Delivery

The power consumption of next-generation high-performance processors is expected to reach and eventually exceed 1000 W, with core logic voltages below 1 V and peak current demand beyond 1000 A. To deliver ultra-high currents at low voltages with minimal power distribution network losses, this paper presents a compact 48-V-to-sub-1-V switching bus converter (SBC), a single-stage hybrid switched-capacitor (SC) voltage regulator for processor vertical power delivery (VPD). The SBC comprises a 2-to-1 SC front-end and two 10-branch series-capacitor buck modules, which are merged through two switching buses. A hardware prototype was designed and built with two-phase coupled inductors for performance validation. The coupled inductors were customized for VPD, with their windings both functioning as part of the coupled inductors and serving as the connection between the SBC and the processor motherboard. The hardware prototype met a stringent maximum height limit of 5 mm and achieved a current density of 0.614 A/mm² at a full-load current of 600 A. Additionally, it demonstrated excellent performance compared to the state-of-the-art academic works for 48 V to point-of-load conversion.