Seth Sanders

Title:   Integrated Power Conversion - The Switched Capacitor Approach
Date:  October 28, 2010, at 3 p.m., in SF1105

Technical merits and challenges of the switched capacitor approach to dc-dc power conversion are discussed. A detailed analysis enabling a strategic comparison among switched-capacitor converter topologies and also enabling comparison of switched-capacitor topologies with conventional magnetic topologies is outlined. The analysis framework allows a quantitative comparison of the various popular power conversion circuits in terms of their utilization of switch technology and also their utilization of energy storage devices (eg. capacitors, inductors). Roughly, the analysis views a power converter as an ideal transformer with a given or adjustable conversion ratio, with losses modeled with a series output resistance for load-dependent losses, and with a parallel resistive impedance to capture frequency-dependent and static leakage losses. Significantly, the analysis shows that for a wide range of conversion applications, switched capacitor converters outperform the conventional buck, boost, and transformer-based converters with respect to component utilization.

Since switched capacitor converters contain no magnetic devices, they are well suited to integration in a range of CMOS processes. Further, since devices can be effectively stacked, extended voltage operation can be realized with low voltage processes. However, switched capacitor converters also present a number of challenges in voltage regulation and in ripple performance. Design strategies to meet these challenges are outlined. Data developed from on-going experimental work will be discussed.

Bio:  Seth R. Sanders is a Professor of Electrical Engineering in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley. He received S.B. degrees (1981) in Electrical Engineering and Physics, and the S.M. (1985) and Ph.D. (1989) degrees in Electrical Engineering from the Massachusetts Institute of Technology, Cambridge. Following an early experience as a Design Engineer at the Honeywell Test Instruments Division in 1981-83, he joined the UC Berkeley faculty in 1989. His research interests are in high-frequency power conversion circuits and components, in design and control of electric machine systems, and in nonlinear circuit and system theory as related to the power electronics field. Dr. Sanders is presently or has recently been active in supervising research projects in the areas of flywheel energy storage, novel electric machine design, renewable energy, and digital pulse-width modulation strategies and associated IC designs for power conversion applications. During the 1992-1993 academic year, he was on industrial leave with National Semiconductor, Santa Clara, CA. Dr. Sanders received the NSF Young Investigator Award in 1993 and multiple Best Paper Awards from the IEEE Power Electronics and the IEEE Industry Applications Societies. He has served as Chair of the IEEE Technical Committee on Computers in Power Electronics, and as a Member-At-Large of the IEEE PELS Adcom. He is an IEEE Fellow.