# Design of Monolithic Step-Up DC-DC Converters with On-Chip Inductors

 Title: Design of Monolithic Step-Up DC-DC Converters with On-Chip Inductors Hasan, Ayaz School of Engineering Engineering Gregori, Stefano This thesis presents the design of a step-up DC-DC converter with on-chip coupled inductors. Circuit theory of DC-DC converters in general is presented, after which a mathematical model of a step up converter is developed. A circuit implementation optimized from results of the mathematical model follows. For a completely integrated step-up converter, the inductor size is reduced by increasing the frequency of operation and using a circuit topology that employs coupled inductors. Spiral inductors are also studied to achieve maximum quality factor and inductance. A fast PWM control system is used to regulate the high-frequency converter. The fabrication was done in standard TSMC 0.18-$\mu$m digital CMOS process for four circuits, including one with a conventional topology and the others with a coupled inductor topology with varying inductor geometries. Measurement results from a fabricated prototype have been presented, demonstrating the functionality of the four circuits with coupled inductors on the fabricated chip and the improvement of the coupled solution over the conventional design. It is demonstrated that the circuits with coupled inductors have a significant improvement in performance based on conversion ratio and efficiency. Finally, the design process is evaluated and recommendations are made for future work. Furthermore, a new self-oscillating and robust control system is proposed that enables simpler and more efficient regulation for high-frequency converters such as one developed for this thesis. http://hdl.handle.net/10214/2893 2011-08 All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
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