A general approach for design optimization of high performance hybrid switched capacitor converters


  • Robert Pilawa-Podgurski, Associate Professor, University of California-Berkeley
  • Nathan Brooks, PhD Candidate, University of California-Berkeley
  • Samantha Coday, PhD Candidate, University of California-Berkeley
  • Nathan Ellis, Post-Doctoral Researcher, University of California-Berkeley
  • Rose Abramson, PhD Student, University of California-Berkeley

Contact information: [pilawa, nathanbrooks, scoday, nathanmilesellis, rose_abramson]@berkeley.edu


This tutorial will cover the design, optimization and implementation of hybrid switched capacitor (SC) converters. First, a motivation for why hybrid SC converters are suitable solutions for power dense and efficient power delivery will be covered. A general introduction to hybrid SC analysis will be reviewed, including charge flow analysis and general topology comparison.  Next, a novel approach to the optimization of hybrid SC converters will be introduced, which allows designers to minimize the volume of their converter while operating both at-resonance and above-resonance. Motivation for operating above resonance will be discussed and experimental hardware results will be used to help motivate the described operations. Throughout the tutorial example designs will be utilized to showcase the utility of the presented methodology, for a wide range of applications including: space applications and data centers. These examples will also showcase some of the practical implementation challenges and proposed solutions for high-performance design. Finally, general figures of merit and key takeaways will be summarized for designers’ consideration.

Detailed Tutorial Outline

  1. Introduction
    1. Benefits of hybrid SC converters
    2. Motivation of operation at and above resonance
  2. Hybrid SC analysis at resonance
    1. Introduction to hybrid SC converter topologies
    2. Charge flow analysis
    3. Introduction to the Energy Method (at resonance)
  3. Optimization of converters at resonance
    1. Volume optimization
    2. Mass optimization
  4. Example 1: Capacitively Isolated Dickson for Space Applications (20 min)
  5. Break (30 min)
  6. Above Resonance Operation
    1. Motivation
    2. Above Resonance analysis
    3. Optimization above resonance
  7. Example 2: FCML converter above resonance (20 min)
  8. Topology Comparisons
    1. Introduction to switch stress metric
    2. Topology comparison using switch stress and minimized passive volume


Robert Pilawa-Podgurski is currently an Associate Professor in the Electrical Engineering and Computer Sciences Department at the University of California, Berkeley. He received his BS, MEng, and PhD degrees from MIT. His research interests include renewable energy applications, electric vehicles, energy harvesting, CMOS power management, high density and high efficiency power converters, and advanced control of power converters. Dr. Pilawa-Podgurski received the Google Faculty Research Award in 2013, and the 2014 Richard M. Bass Outstanding Young Power Electronics Engineer Award of the IEEE Power Electronics Society, given annually to one individual for outstanding contributions to the field of power electronics before the age of 35. In 2015, he received the AFOSR Young Investigator Award, the UIUC Dean’s Award for Excellence in Research in 2016, and the UIUC ECE Ronald W. Pratt Faculty Outstanding Teaching Award in 2017. In 2018, he received the IEEE Education Society Mac E. Van Valkenburg Award, for outstanding contributions to teaching unusually early in his professional career. From 2014 to 2019, he served as Associate Editor for IEEE Transactions on Power Electronics, and for IEEE Journal of Emerging and Selected Topics in Power Electronics. He is co-author of thirteen IEEE prize papers.

Nathan Brooks received his B.S. degree from Rose-Hulman Institute of Technology in 2016 and M.S. degree from University of Illinois at Urbana-Champaign in 2018 both in Electrical Engineering. He is currently pursuing his Ph.D. degree in Electrical Engineering at the University of California, Berkeley. His research interests include high density single-phase multi-level power converters with emphasis on control and hardware optimization, modeling and simulation, and passive component characterization.

Samantha Coday is a PhD candidate at University of California, Berkeley, advised by Dr. Robert Pilawa-Podgurski. Samantha received her Bachelor’s degree in Electrical Engineering and Mathematics, in 2017, from Southern Methodist University. She then completed her Masters in 2019, at UC Berkeley. Her current research interests are in the design of light-weight multilevel switched capacitor power converters with applications in aerospace. Samantha has been selected as a 2021 EECS Rising Star, a Cadence Women in Technology Scholarship winner and an Outstanding Graduate Student Instructor.

Nathan M. Ellis received the B.S. degree in Electrical and Electronic Engineering from the University College Cork, Ireland, in 2013, and the M.S. and Ph.D degrees in Electrical and Computer Engineering from the University of California, Davis in 2017 and 2020 respectively. During this time he was funded in part by both Texas Instruments and the U.S. Dept. of Education in recognition of research excellence in areas of national need. He is currently a Post-Doctoral Researcher at the University of California, Berkeley within the Department of Electrical Engineering and Computer Sciences. He is an author on over 30 journal and conference publications and holds four U.S. patents. His research interests include Mixed Signal Integrated Circuit Design, Energy Harvesting, Renewable Energy Integration, Biomedical Devices, and spans several topics in high performance power converter design, including; Hybridized Switched-Capacitor Power Converters, Multi-Level Converters, and Adiabatic Gate-Drives. Dr. Ellis was named Best Graduate Researcher by UC Davis’ Industrial Affiliates in 2017, and he received the title of Analog Devices Outstanding Student Designer at the International Solid-State Circuits Conference (ISSCC) in 2020. He is an author on four IEEE prize papers.

Rose Abramson received the B.S. and M.Eng degree in Electrical Engineering from Massachusetts Institute of Technology, Cambridge, MA in 2015 and 2016, respectively. After graduating, she worked at an EV startup developing power systems and drivetrains, and then at Lutron Electronics, Inc. developing offline LED drivers. She is currently pursuing her Ph.D. in Electrical Engineering at the University of California, Berkeley. Rose is a 2019 NDSEG Fellow and a recipient of the 2021 IEEE Joseph John Suozzi INTELEC Fellowship Award in Power Electronics. Her research focus includes hybrid and resonant switched-capacitor circuits and high-performance DC-DC conversion for data center applications.