Differential power processing for series-stacked processors

The series-stacked architecture provides a method to increase power delivery efficiency to multiple processors. With a series-stack, differential power processing (DPP) is needed to ensure that processor voltages remain within design limits as the individual loads vary. This work demonstrates a switched-capacitor (SC) converter to balance a stack of four ARM Cortex-A8 based embedded computers. A model of a series-stack with no DPP is first discussed for the case when loads can be controlled with no power electronics. We investigate hard-switched and resonant modes of operation in a ladder SC DPP converter, implemented with GaN transistors. Excellent 5 V regulation of each embedded computer is demonstrated in a 4-series-stack configuration, with realistic computational workloads. Moreover, we demonstrate hot-swapping of individual computers with maintained voltage regulation at all nodes. A peak stack power delivery of 99.8% is demonstrated, and DPP switching frequencies from 250 kHz to 2 MHz. Finally, the reliability of a series-stacked system is compared to an electrically parallel system.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical & Computer Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Stillwell, Andrew R

Contributors dc:contributor

• Pilawa, Robert

• power
• switched-capacitor

Statement dc:rights

• Copyright 2015 Andrew Stillwell

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/88081

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/88081