A 48-V-to-1-V Gallium Nitride Switching Bus Converter for Processor Vertical Power Delivery with 2.7 mm Thickness and 3048 W/in³ Power Density

High-performance processors demand over 1000 A of current at a core voltage of 1 V or lower when running computationally intensive tasks, demanding improved 48 V to point-of-load (PoL) power conversion solutions with high efficiency and power density. In pursuit of improved performance for 48-V-to-PoL conversion, a switching bus converter (SBC) was recently proposed to achieve single-stage vertical power delivery and pushed the performance boundary of existing solutions. This work presents an ultra-low-profile, high-density implementation of the SBC, with high switching frequency enabled by Gallium Nitride field-effect transistors and an advanced packaging structure featuring recessed coupled inductors for vertical current flow. A 2.7 mm thick low-profile SBC hardware prototype was designed and built for 48-V-to-1-V conversion. The prototype was tested up to 405 A of output current at an output voltage of 1 V, achieving a high power density of 3048W/in<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>. At 0.8V and 420 A, it reached a power density of 2529 W/in<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, demonstrating promising performance compared to state-of-the-art solutions.