A 2400 W/in3 1.8 V Bus Converter Enabling Vertical Power Delivery for Next-Generation Processors

The advances in artificial intelligence and machine learning are leading to the emergence of a new generation of ultra-powerful graphical processing units (GPUs). The latest datacenter-grade GPU cards are overwhelmed with power delivery circuits using the traditional two-stage with a 12V intermediate bus voltage (IBV). The next-generation GPU is expected to double in power and package size, leaving even tighter space for power delivery. Recently, the vertical power delivery architecture has gained traction to address this challenge. This paper focuses on a two-stage vertical power delivery solution with an IBV of 1.8V. Stage 1 is a DC transformer stepping down 48V to 1.8V and stage 2 is a high-density 1.8V/0.8V packaged voltage regulator (VR) which is stacked under the GPU. This work is focusing on the design of stage 1 using an LLC resonant converter which features soft-switching, and hence high frequency and high-power density. The converter is designed with an array of 14 transformers, each carrying 60A, distributed along the edge of the GPU package to minimize the power distribution network (PDN) losses at 1.8V. The converter module can achieve up to 95% efficiency, while showcasing a power density of 2400 W/in ³ .