ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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Small Form Factor Hybrid CMOS/GaN Buck Converters for 10W Point of Load Applications

Description
Point of Load (PoL) converters are important components to the power distribution system in computer power supplies as well as automotive, space, nuclear, and medical electronics. These converters often require high output current capability, low form factor, and high conversion ratios (step-down) without sacrificing converter efficiency. This work presents hybrid…

Point of Load (PoL) converters are important components to the power distribution system in computer power supplies as well as automotive, space, nuclear, and medical electronics. These converters often require high output current capability, low form factor, and high conversion ratios (step-down) without sacrificing converter efficiency. This work presents hybrid silicon/gallium nitride (CMOS/GaN) power converter architectures as a solution for high-current, small form-factor PoL converters. The presented topologies use discrete GaN power devices and CMOS integrated drivers and controller loop. The presented power converters operate in the tens of MHz range to reduce the form factor by reducing the size of the off-chip passive inductor and capacitor. Higher conversion ratio is achieved through a fast control loop and the use of GaN power devices that exhibit low parasitic gate capacitance and minimize pulse swallowing.

This work compares three discrete buck power converter architectures: single-stage, multi-phase with 2 phases, and stacked-interleaved, using components-off-the-shelf (COTS). Each of the implemented power converters achieves over 80% peak efficiency with switching speeds up-to 10MHz for high conversion ratio from 24V input to 5V output and maximum load current of 10A. The performance of the three architectures is compared in open loop and closed loop configurations with respect to efficiency, output voltage ripple, and power stage form factor.

Additionally, this work presents an integrated CMOS gate driver solution in CMOS 0.35um technology. The CMOS integrated circuit (IC) includes the gate driver and the closed loop controller for directly driving a single-stage GaN architecture. The designed IC efficiently drives the GaN devices up to 20MHz switching speeds. The presented controller technique uses voltage mode control with an innovative cascode driver architecture to allow a 3.3V CMOS devices to effectively drive GaN devices that require 5V gate signal swing. Furthermore, the designed power converter is expected to operate under 400MRad of total dose, thus enabling its use in high-radiation environments for the large hadron collider at CERN and nuclear facilities.
ContributorsHegde, Ashwath (Author) / Kitchen, Jennifer (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2018