UC Berkeley

Power Electronics Group

Power Electronics Group

The Power Electronics Group is in the
Electrical Engineering and Computer Sciences (EECS) department at the
University of California, Berkeley.
Professor Seth Sanders advises the group on research in the areas of power electronics, switching converters, and energy systems.

Power Electronics Group

406 Cory Hall

Berkeley, CA 94720-1772

406 Cory Hall

Berkeley, CA 94720-1772

Seth R. Sanders received the S.B. degrees in electrical engineering and physics and the S.M. and Ph.D. degrees in electrical engineering from the Massachusetts Institute of Technology, Cambridge, in 1981, 1985, and 1989, respectively.

He was a Design Engineer at the Honeywell Test Instruments Division, Denver, CO. Since 1989, he has been on the faculty of the Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, where he is presently Professor. 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. He is presently actively 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 to 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 Best Paper Awards from the IEEE Power Electronics Society and the IEEE Industry Applications Society. 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 was a Design Engineer at the Honeywell Test Instruments Division, Denver, CO. Since 1989, he has been on the faculty of the Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, where he is presently Professor. 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. He is presently actively 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 to 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 Best Paper Awards from the IEEE Power Electronics Society and the IEEE Industry Applications Society. 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.

- Mike He
- Kun Wang
- Hanh Phuc Le
- Mitchel Kline
- Denise Loeder
- Nic Beutler
- Vincent Ng
- Evan Reutzel
- Jason Stauth
- Michael Seeman
- Artin Der Minassians
- Timothy Loo
- Gabriel Eirea
- Jianhui (Kenny) Zhang
- Angel Peterchev
- Matthew Senesky
- Yi Zhang
- Konrad Hsu Aschenbach
- Eula Fung
- Heath Hofmann
- Linda Kamas
- Wai Lau
- Mariam Motamed
- J. Mark Noworolski
- Anthony Stratakos
- Charles R. Sullivan
- Perry Tsao
- Jinwen Xiao
- Denise Wolf
- Albert Wu

- Dr. Carsten Nesgaard
- Dr. Johan Driesen
- Dr. Seleme I. Seleme
- Dr. Kenichi Nakashi

April '15: Class trip to Makani Power in Alameda.

Group in April '14: (left to right) Jason Poon, Daniel Gerber, Prof. Seth Sanders, Achintya Madduri, Yongjun Li, Mervin John

Group in April '12: (left to right) Kun Wang, Nic Beutler, Daniel Gerber, Prof. Seth Sanders, Mike He, Denise Loeder, Achintya Madduri, Mervin John, Hanh Phuc Le, Alan Harbottle (UG)

Group in May '07: (left to right) Jason Stauth, Tim Loo, Artin Der Minassians, Kun
Wang, Michael Seeman, Thura Lin Naing (UG), Evan Reutzel, Vincent Ng, Charles Wu (UG),
Dr. Seth Sanders. Not Shown: Mike He

- Achintya Madduri, "A Scalable DC Microgrid Architecture for Rural Electrification in Emerging Regions", Ph.D. Thesis, EECS Department, University of California, Berkeley, Dec 16, 2015, PDF
- Jason Poon, "Model-Based Fault Detection and Identification for Power Electronics Systems", Master's Thesis, EECS Department, University of California, Berkeley, Dec 15, 2015, PDF
- Jason Poon, Ioannis C. Konstantakopoulos, Reza Arghandeh, Palak Jain, Jaime F. Fisac, S. Shankar Sastry, Sanjib Kumar Panda, Costas Spanos, Seth R. Sanders, "FailSafe: A Generalized Methodology for Converter Fault Detection, Identification, and Remediation in Nanogrids", IEEE International Conference on Building Energy Efficiency and Sustainable Technologies (ICBEST 2015), August 31, 2015, PDF
- Yongjun Li, Mervin John, Jason Poon, Jikang Chen, Seth R. Sanders, "Lossless Voltage Regulation and Control of the Resonant Switched-Capacitor DC-DC Converter", IEEE Workshop on Control and Modeling for Power Electronics, COMPEL 2015, July 12-15, 2015, PDF
- Jason Poon, Ioannis C. Konstantakopoulos, Costas Spanos, Seth R. Sanders, "Real-Time Model-Based Fault Diagnosis for Switching Power Converters", 2015 IEEE Applied Power Electronics Conference (APEC) , March 15-19, 2015, PDF
- P. Achintya Madduri, Jason Poon, Javier Rosa, Matthew Podolsky, Eric Brewer, Seth R. Sanders, "A Scalable DC Microgrid Architecture for Rural Electrification in Emerging Regions", 2015 IEEE Applied Power Electronics Conference (APEC) , March 15-19, 2015, PDF

- Kun Wang, Seth R. Sanders, "Contactless USB – A Capacitive Power and Bidirectional Data Transfer System", 2014 IEEE Applied Power Electronics Conference (APEC) , March 16-20, 2014, PDF

- Chengrui Le, Mitchell Kline, Daniel L. Gerber, Seth R. Sanders, Peter R. Kinget, "A Stackable Switched-Capacitor DC/DC Converter IC for LED Drivers with 90% Efficiency", 2013 IEEE Custom Integrated Circuits Conference (CICC) , Sept 23-25, 2013, PDF
- P. Achintya Madduri, Javier Rosa, Eric A. Brewer, Seth R. Sanders and Matthew Podolsky, "Design and Verification of Smart and Scalable DC Microgrids for Emerging Regions", 2013 IEEE Energy Conversion Congress and Exposition (ECCE), Sept 9-16, 2013, PDF
- Seth R. Sanders, Elad Alon, Michael D. Seeman, Mervin John and Vincent W. Ng, "The Road to Fully Integrated DC–DC Conversion via the Switched-Capacitor Approach", IEEE Transactions on Power Electronics, Sept , 2013, PDF
- Hanh-Phuc Le, John Crossley, Seth R. Sanders and Elad Alon, "A sub-ns response fully integrated battery-connected switched-capacitor voltage regulator delivering 0.19W/mm2 at 73% efficiency", 2013 IEEE International Solid-State Circuits Conference (ISSCC), Feb 17-21, 2013, PDF

- Jesse Richmond, Mervin John, Louis Alarcon, Wenting Zhou, Wen Li, Tsung-Te Liu, Massimo Alioto, Seth R. Sanders, Jan M. Rabaey, "Active RFID: Perpetual Wireless Communications Platform for Sensors ", IEEE European Solid State Circuits Conference (ESSCIRC), Sept 17-21, 2012, PDF
- Achintya Madduri, Denise Loeder, Nic Beutler, Mike He, Seth R. Sanders, "Concentrated evacuated tubes for solar-thermal energy generation using stirling engine", 2012 IEEE Energytech, May 29-31, 2012, PDF
- Mitchell Kline, Igor Izyumin, Bernhard Boser, Seth Sanders, "A transformerless galvanically isolated switched capacitor LED driver", Applied Power Electronics Conference and Exposition (APEC), Feb 5-9, 2012, PDF
- Vincent Ng, Seth Sanders, "A 92%-Efficiency Wide-Input-Voltage-Range Switched-Capacitor DC-DC Converter", IEEE International Solid States Circuit Conference (ISSCC), Feb 21, 2012, PDF

- Mike He, Seth Sanders, "Design of a 2.5kW Low Temperature Stirling Engine for Distributed Solar Thermal Generation", 9th Annual International Energy Conversion Engineering Conference, August 8-1, 2011, PDF
- Hanh-Phuc Le, Seth R. Sanders, and Elad Alon, "Design Techniques for Fully Integrated Switched-Capacitor DC-DC Converters", IEEE Journal of Solid-State Circuits, Sept, 2011, PDF
- Vincent W. Ng, "Switched Capacitor DC-DC Converter: Superior where the Buck Converter has Dominated", Ph.D. Thesis, EECS Department, University of California, Berkeley, Tech. Rep. UCB/EECS-2011-94, Aug, 2011, PDF
- Mitchell Kline, Igor Izyumin, Bernhard Boser, and Seth Sanders, "Capacitive Power Transfer for Contactless Charging", Proc. IEEE Applied Power Electronics Conference, pp. 1398-1404, March 6-10, 2011, PDF
- Randy H. Katz, David E. Culler, Seth Sanders, Sara Alspaugh, Yanpei Chen, Stephen Dawson-Haggerty, Prabal Dutta, Mike He, Xiaofan Jiang, Laura Keys, Andrew Krioukov, Ken Lutz, Jorge Ortiz, Prashanth Mohan, Evan Reutzel, Jay Taneja, Jeff Hsu and Sushant Shankar, "An information-centric energy infrastructure: The Berkeley view", Sustainable Computing: Informatics and Systems, vol. 1, no. 1, pp. 7-22, March, 2011
- A. Der Minassians and S. R. Sanders, "Stirling Engines for Distributed Low-Cost Solar-Thermal-Electric Power Generation", ASME Journal of Solar Energy Engineering, vol. 133, no. 1, Feb 14, 2011, PDF

- MD Seeman, VW Ng, H-P Le, M. John, E. Alon, SR Sanders, "The Future of Integrated Power Conversion: The Switched Capacitor Approach", IEEE COMPEL Workshop, Boulder CO, pp. 1430-1434, June 28-30, 2010, PDF
- Evan Reutzel and Seth Sanders, "A Single-Stage Single-Phase Bi-Directional Grid Interface Circuit with Digital Lookup Table Based Control", Proc. IEEE Applied Power Electronics Conference, pp. 1430-1434, Feb 21-25, 2010, PDF
- Hanh-Phuc Le, Mike Seeman, Seth Sanders, Visvesh Sathe, Samuel Naffziger, and Elad Alon, "A 32nm Fully Integrated Reconfigurable Switched-Capacitor DC-DC Converter Delivering 0.55W/mm2 at 81% Efficiency", ISSCC Dig. Tech. Papers, pp. 210-211, 2010, PDF

- Vincent Ng, Mike Seeman, Seth Sanders, "Minimum PCB Footprint Point-of-Load DC-DC Converter Realized with Switched Capacitor Architecture", Energy Conversion Congress and Exposition, , 2009, PDF
- Vincent Ng, Mike Seeman, Seth Sanders, "High-Efficiency, 12V-to-1.5V DC-DC Converter Realized with Switched Capacitor Architecture", Symposium on VLSI Circuits Digital, pp. 168-169, 2009, PDF
- Jason Thaine Stauth and Seth R. Sanders, "Energy Efficient Wireless Transmitters: Polar and Direct-Digital Modulation Architectures", PhD Thesis, EECS Department, U.C. Berkeley, Feb 4, 2009, PDF
- Kun Wang, "Efficiency Optimization for Dynamic Supply Modulation of RF Power Amplifiers", Master's Thesis, EECS Department, University of California, Berkeley, December, 2009, PDF
- M. D. Seeman, "A Design Methodology for Switched-Capacitor DC-DC Converters", Ph.D. Thesis, EECS Department, University of California, Berkeley, Tech. Rep. UCB/EECS-2009-78, May, 2009, PDF
- A. Der Minassians and S. R. Sanders, "Multi-Phase Stirling Engines", ASME Journal of Solar Energy Engineering, vol. 131, no. 2, May, 2009, PDF

- Mike M. He, Evan M. Reutzel, Xiaofan Jiang, Randy H. Katz, Seth R. Sanders, David E. Culler, Ken Lutz, "An Architecture for Local Energy Generation, Distribution, and Sharing", IEEE Energy2030 Conference Proceedings, Nov 17-18, 2008, PDF
- J. T. Stauth and S.R. Sanders, "A 2.4GHz, 20dBm class-D PA with single-bit digital polar modulation in 90nm CMOS", IEEE Custom Integrated Circuits Conference, pp. 737-740, Sept 21-24, 2008, PDF
- A. Der Minassians and S. R. Sanders, "Multi- Phase Stirling Engines ", 6th International Energy Conversion Engineering Conference and Exhibit (IECEC), July 28-30, 2008
- M. Senesky and S.R. Sanders, "A Millimeter-Scale Electric Generator", IEEE Transactions on Industry Applications, July-Aug 25, 2008, PDF
- M.D. Seeman, S.R. Sanders and J.M. Rabaey, "An Ultra-Low-Power Power Management IC for Energy-Scavenged Wireless Sensor Nodes", IEEE Power Electronics Specialists Conference, pp. 925-931, June 15-19, 2008, PDF
- J. T. Stauth and S.R. Sanders, "Pulse-density modulation for RF applications: The radio-frequency power amplifier (RF PA) as a power converter", IEEE Power Electronics Specialists Conference, pp. 3563-3568, June 15-19, 2008, PDF
- G. Eirea, S.R. Sanders, "High Precision Load Current Sensing Using On-Line Calibration of Trace Resistance", IEEE Transactions on Power Electronics, vol. 23, no. 2, pp. 907-914, March, 2008, PDF
- M.D. Seeman and S.R. Sanders, "Analysis and Optimization of Switched-Capacitor DC-DC Converters", IEEE Transactions on Power Electronics, vol. 23, no. 2, pp. 841-851, March, 2008, PDF
- V. Ng and S. R. Sanders, "A 98% Peak Efficiency 1.5A 12V-to-1.5V Switched Capacitor DC-DC Converter in 0.18um CMOS Technology", Master's Thesis, EECS Department, University of California, Berkeley, Jan 13, 2008, PDF
- G. Eirea, S.R. Sanders, "Phase Current Unbalance Estimation in Multiphase Buck Converters", IEEE Transactions on Power Electronics, vol. 23, no. 1, pp. 137-143, Jan, 2008, PDF

- Artin Der Minassians, "Stirling Engines for Low-Temperature Solar-Thermal-Electric Power Generation", PhD Thesis, U.C. Berkeley, December 20, 2007, PDF
- Timothy C Loo. , "High Speed DPWM Switched Mode Supply and Control", Master's Thesis, EECS Department, University of California, Berkeley, Dec, 2007, PDF
- J. T. Stauth and S. R. Sanders, "Power Supply Rejection for Radio Frequency Amplifiers: Theory and Measurements", IEEE Transactions on Microwave Theory and Techniques, vol. 55, no. 10, pp. 2043-2052, Oct, 2007, PDF
- M.D. Seeman, S.R. Sanders and J.M. Rabaey, "An Ultra-Low-Power Power Management IC for Wireless Sensor Nodes", IEEE Custom Integrated Circuits Conference, pp. 567-570, Sept 16-19, 2007, PDF
- J. T. Stauth and S. R. Sanders, "Optimum Biasing for Parallel Hybrid Switching-Linear Regulators", IEEE Transactions on Power Electronics, vol. 22, no. 5, pp. 1978-1985, Sept, 2007, PDF
- A. Der Minassians and S. R. Sanders, "Multiphase Free-Piston Stirling Engine for Solar-Thermal-Electric Power Generation Applications", 5th International Energy Conversion Engineering Conference and Exhibit (IECEC), June 25-27, 2007, PDF
- A. Der Minassians and S. R. Sanders, "A Magnetically-Actuated Resonant-Displacer Free-Piston Stirling Machine", 5th International Energy Conversion Engineering Conference and Exhibit (IECEC), June 25-27, 2007, PDF
- G. Eirea and S.R. Sanders, "Adaptive Output Current Feedforward Control in VR Applications", Proceedings of Power Electronics Specialists Conference (PESC), June 17-21, 2007, PDF
- R. J. Wood, S. Avadhanula, E. Steltz, M. Seeman, J. Entwistle, A. Bachrach, G. Barrows, S. Sanders, R. S. Fearing,, "An Autonomous Palm-Sized Gliding Micro Air Vehicle", Robotics and Automation Magazine, vol. 14, no. 2, pp. 82-91, June, 2007, PDF
- J. Zhang and S.R. Sanders, "A Digital Multi-Mode Multi-Phase IC Controller for Voltage Regulator Application", Proceedings of the Applied Power Electronics Conference, pp. 719-726, Feb 25, 2007, PDF
- J. T. Stauth and S.R. Sanders, "Optimum Bias Calculation for Parallel Hybrid Switching-Linear Regulators", Proceedings of the Applied Power Electronics Conference (APEC), pp. 569-574, Feb 25, 2007, PDF
- J. Zhang and S.R. Sanders, "An Analog CMOS Double-Edge Multi-Phase Low-Latency Pulse Width Modulator", Proceedings of the Applied Power Electronics Conference , pp. 355-360, Feb 25, 2007, PDF

- J. Zhang, "Advanced Pulse Width Modulation Controller ICs for Buck DC-DC Converters", PhD Thesis, U.C. Berkeley, December 14, 2006, PDF
- A. V. Peterchev and S. R. Sanders, "Digital Multimode Buck Converter Control With Loss-Minimizing Synchronous Rectifier Adaptation", IEEE Transactions on Power Electronics, vol. 21, no. 6, pp. 1588-1599, Nov, 2006, PDF
- A. V. Peterchev and S. R. Sanders, "Load-Line Regulation With Estimated Load-Current Feedforward: Application to Microprocessor Voltage Regulators", IEEE Transactions on Power Electronics, vol. 21, no. 6, pp. 1704-1717, Nov, 2006, PDF
- G. Eirea, "Estimation and Control Techniques in Power Converters", PhD Thesis, U.C. Berkeley, Fall, 2006, PDF
- M. Seeman and S.R. Sanders, "Analysis and Optimization of Switched-Capacitor DC-DC Converters", 10th IEEE Workshop on Computers in Power Electronics (COMPEL), p. 9, July 16-19, 2006, PDF
- G. Eirea and S.R. Sanders, "Phase Current Unbalance Estimation in Multi-Phase Buck Converters", Proceedings of the Power Electronics Specialists Conference, pp. 1-6, June 18-22, 2006, PDF
- G. Eirea and S.R. Sanders, "High Precision Load Current Sensing using On-Line Calibration of Trace Resistance in VRM Applications", Proceedings of the Power Electronics Specialists Conference, pp. 1-6, June 18-22, 2006, PDF
- J. T. Stauth and S. R. Sanders, "Power Supply Rejection for Common-Source Linear RF Amplifiers: Theory and Measurements", Radio Frequency Integrated Circuits (RFIC) Symposium, p. 4, June 11-13, 2006, PDF
- J. T. Stauth and S.R. Sanders, "Supply Rejection for Common-Source Linear RF Amplifiers: Theory and Measurements", RFIC Symposium Digest, p. 4, June 11-13, 2006, PDF
- J. Stauth, "Dynamic Power Supply Design for High-Efficiency Wireless Transmitters", MS Thesis, U.C. Berkeley, May 19, 2006, PDF
- M. Seeman, "Analytical and Practical Analysis of Switched-Capacitor DC-DC Converters", MS Thesis, U.C. Berkeley, May 19, 2006, PDF

- R. J. Wood, S. Avadhanula, E. Steltz, M. Seeman, J. Entwistle, A. Bachrach, G. Barrows, S. R. Sanders, and R. S. Fearing, "Design, Fabrication and Initial Results of a 2g Autonomous Glider", Proc. 31st Annual Conference of the IEEE Industrial Electronics Society (IECON 2005), pp. 1870-1877, Nov 6-10, 2005, PDF
- A. Peterchev, "Digital Pulse-Width Modulation Control in Power Electronic Circuits: Theory and Applications", PhD Dissertation, U.C. Berkeley, June, 2005, PDF
- M. Senesky, "Electromagnetic Generators for Portable Power Applications", PhD Dissertation, U.C. Berkeley, June, 2005, PDF

- J. Xiao, A. Peterchev, J. Zhang, S.R. Sanders, "A 4uA-Quiescent-Current Dual-Mode Buck Converter IC for Cellular Phone Applications", IEEE Journal of Solid State Circuits, vol. 39, no. 12, pp. 2342-2348, Dec, 2004, PDF
- M.K. Senesky, S.R. Sanders, "A Millimeter-Scale Electric Generator", IEEE Annual Industry Applications Society Meeting, vol. 1, pp. 346-352, Oct 3-7, 2004, PDF
- H.F. Hofmann, S.R. Sanders, A. El-Antably, "Stator-Flux-Oriented Vector Control of Synchronous Reluctance Machines with Maximized Efficiency", IEEE Transactions on Industrial Electronics, vol. 51, no. 5, pp. 1066-1072, Oct, 2004, PDF
- A. V. Peterchev, S. R. Sanders, "Design of Ceramic-Capacitor VRM's with Estimated Load Current Feedforward", Proc. 35th IEEE Power Electronics Specialists Conference, vol. 6, pp. 4325-4332, June 20-25, 2004, PDF
- A. V. Peterchev, S. R. Sanders, "Digital Loss-Minimizing Multi-Mode Synchronous Buck Converter Control", Proc. 35th IEEE Power Electronics Specialists Conference, vol. 5, pp. 3694-3699, June 20-25, 2004, PDF
- J. Xiao, A. V. Peterchev, J. Zhang, and S. R. Sanders, "An Ultra-Low-Power Digitally-Controlled Buck Converter IC for Cellular Phone Applications", IEEE Applied Power Electronics Conference, vol. 1, pp. 383-391, Feb 22-26, 2004, PDF
- A. Der Minnassians, K.H. Aschenbach, S.R. Sanders, "Low-Cost Distributed Solar-Thermal-Electric Power Generation", Nonimaging Optics: Maximum Efficiency Light Transfer VII, edited by Roland Winston, Proceedings of SPIE, vol. 5185, pp. 89-98, Jan 8, 2004, San Diego, CA, USA, PDF
- J. Xiao, A. V. Peterchev, J. Zhang, and S. R. Sanders, "A 4uA Quiescent-Current Dual-Mode Buck Converter IC for Cellular Phone Applications", IEEE International Solid-State Circuits Conference, vol. 47, pp. 280-281, 2004, PDF
- M.K. Senesky, P. Tsao, S.R. Sanders, "Simplified Modeling and Control of a Synchronous Machine with Variable-Speed Six-Step Drive", Nineteenth Annual IEEE Applied Power Electronics Conference and Exposition (IEEE Cat. No.04CH37520), vol. 3, pp. 1803-1809, 2004, Piscataway, NJ, USA, PDF
- Y.E. Zhang, S.R. Sanders, "Design, Manufacture and Application of In-board Magnetic Devices", 4th International Power Electronics and Motion Control Conference, vol. 3, pp. 1791-1798, 2004, PDF

- Perry Tsao, M. Senesky, S.R. Sanders, "An Integrated Flywheel Energy Storage System with Homopolar Inductor Motor/Generator and High-Frequency Drive", IEEE Transactions on Industry Applications, vol. 39, no. 6, pp. 1710-1725, Nov-Dec, 2003, PDF
- P. Tsao, "An Integrated Flywheel Energy Storage System with a Homopolar Inductor Motor/Generator and High-Frequency Drive", PhD Dissertation, U.C. Berkeley, September, 2003, PDF
- J. Xiao, "An Ultra Low Quiescent Current Dual-Mode Digitally-Controlled Buck Converter IC for Cellular Phone Applications", PhD Dissertation, U.C. Berkeley, September, 2003, PDF
- A.C. Fernandez-Pello, A.P. Pisano,K. Fu,D.C Walther,A. Knobloch,F. Martinez, M. Senesky,C. Stoldt,R. Maboudian,S. Sanders, D. Liepmann, "MEMS Rotary Engine Power System", Transactions of the Institute of Electrical Engineers of Japan, vol. 123-E, no. 9, pp. 326-330, Sept, 2003, Japan
- A.V. Peterchev, S.R. Sanders, "Quantization Resolution and Limit Cycling in Digitally Controlled PWM Converters", IEEE Transactions on Power Electronics, vol. vol.18, no. no.1, pt. 2, pp. 301-308, Jan, 2003, PDF
- A.V. Peterchev, Jinwen Xiao, S.R. Sanders, "Architecture and IC Implementation of a Digital VRM Controller", IEEE Transactions on Power Electronics, vol. 18, no. 1, pt. 2, pp. 356-364, Jan, 2003, PDF

- A.V. Peterchev, "Digital Control of PWM Converters: Analysis and Application to Voltage Regulation Modules", MS Thesis, U.C. Berkeley, May, 2002, PDF
- A.M. Stankovic, S.R. Sanders, T. Aydin, "Dynamic Phasors in Modeling and Analysis of Unbalanced Polyphase AC Machines", IEEE Transactions on Energy Conversion, vol. 17, no. 1, pp. 107-113, March, 2002, PDF
- A.M. Flynn, S.R. Sanders, "Fundamental Limits on Energy Transfer and Circuit Considerations for Piezoelectric Transformers", IEEE Transactions on Power Electronics, vol. 17, no. 1, pp. 8-14, Jan, 2002, PDF
- A.V. Peterchev, S.R. Sanders, "Low Conversion Ratio VRM Design", 33rd Annual IEEE Power Electronics Specialists Conference, vol. 4, pp. 1571-1575, 2002, PDF
- P. Tsao, M. Senesky, S. Sanders., "A Synchronous Homopolar Machine for High-Speed Applications", IEEE Industry Applications Conference, vol. 1, pp. 406-416, 2002, PDF

- A. M. Wu, S.R. Sanders, "An Active Clamp Circuit for Voltage Regulation Module (VRM) Applications", IEEE Transactions on Power Electronics, vol. 16, no. 5, pp. 623-634, Sept, 2001, PDF
- A.V. Peterchev, S.R. Sanders, "Quantization Resolution and Limit Cycling in Digitally Controlled PWM Converters", IEEE Power Electronics Specialists Conference, 2001, PDF
- J. Xiao, A.V. Peterchev, S.R. Sanders, "Architecture and IC Implementation of a Digital VRM Controller", IEEE Power Electronics Specialists Conference, 2001, PDF
- A.M. Stankovic, G. Escobar, R. Ortega, S.R. Sanders, "Energy-Based Control in Power Electronics", Nonlinear Phenomena in Power ElectronicsY:\publications.xml , by S. Banerjee and G.C. Verghese, 2001

- H. Hofmann, S.R. Sanders, "High-Speed Synchronous Reluctance Machine with Minimized Rotor Losses", IEEE Transactions on Industry Applications, vol. 36, no. 2, pp. 531-539, March-April, 2000, PDF

- Y.E. Zhang, S.R. Sanders, "In-board Magnetics Processes", IEEE Power Electronics Specialists Conference, vol. 1, pp. 561-567, Aug, 1999, PDF
- Daniel, L., C.R. Sullivan, S.R. Sanders, "Design of Microfabricated inductors", IEEE Transactions on Power Electronics, vol. 14, no. 4, pp. 709-23, July, 1999, PDF
- H. Hofman, S.R. Sanders, S. Herold, G.M. Maier, "Vector Torque Control of AC Induction Machines at DC Electrical Frequency Using Hall Effect Sensors", Proc. of 28th Annual Symposium on Incremental Motion Control Systems and Devices, July, 1999, San Jose, CA
- A.M. Wu, Jinwen Xiao, D. Markovic, S.R. Sanders, "Digital PWM Control: Application in Voltage Regulation Modules", IEEE Power Electronics Specialists Conference, vol. 1, pp. 77-83, 1999, PDF
- P. Tsao, S.R. Sanders, G. Risk, "A Self-Sensing Homopolar Magnetic Bearing: Analysis and Experimental Results", IEEE Industry Applications Conference, vol. 4, pp. 2560-2565, 1999, PDF
- A.J. Stratakos, C.R. Sullivan, S.R. Sanders, R.W. Brodersen, "High-Efficiency Low-Voltage DC-DC Conversionfor Portable Applications", Low-Voltage/Low-Power Integrated Circuits and SystemsY:\publications.xml , edited by E. Sanchez-Sinencio and A.G. Andreou, 1999

- H. Hofmann, S.R. Sanders, "Speed-Sensorless Vector Torque Control of Induction Machines Using a Two-Time-Scale Approach", IEEE Transactions on Industry Applications, vol. 34, no. 1, pp. 169-177, Jan-Feb, 1998, PDF
- H. Hofmann, S.R. Sanders, "Optimal Efficiency Controller for Synchronous Reluctance Flywheel Drive", INTELEC - Twentieth International Telecommunications Energy Conference, pp. 724-731, 1998
- J.M. Noworolski, S.R. Sanders, "Microresonant Devices for Power Conversion", Proceedings of the SPIE - The International Society for Optical Engineering, vol. 3514, pp. 260-265., 1998
- J.M. Noworolski, S.R. Sanders, "Self-Aligned Polysilicon MEMS-Reduced Mask Count Surface Micromachining", Proceedings of the SPIE - The International Society for Optical Engineering, vol. 3514, pp. 316-321, 1998
- A.M. Flynn, S.R. Sanders , "Fundamental Limits on Energy Transfer and Circuit Considerations for Piezoelectric Transformers", IEEE Power Electronics Specialists Conference, vol. 2, pp. 1463-1471, 1998, PDF

- H. Hofmann, S.R. Sanders, C.R. Sullivan, "Stator-Flux-Based Vector Control of Induction Machines in Magnetic Saturation", IEEE Transactions on Industry Applications, vol. 33, no. 4, pp. 935-942, July-Aug, 1997, PDF
- C.R. Sullivan, S.R. Sanders, "Soft-Switched Square-Wave Half-Bridge DC-DC Converter", IEEE Transactions on Aerospace and Electronic Systems, vol. 33, no. 2, pt. 1, pp. 456-463, April, 1997, PDF
- Wai Lau, S.R. Sanders, "An Integrated Controller for a High Frequency Buck Converter", IEEE Power Electronics Specialists Conference, vol. 1, pp. 246-254, 1997, PDF
- S.R. Sanders, Albert Wu, R. Rossetti, "Active Clamp Circuits for Switchmode Regulators Supplying Microprocessor Loads", IEEE Power Electronics Specialists Conference, vol. 2, pp. 1179-1185, 1997, PDF

- D.M. Wolf, S.R. Sanders, "Multiparameter Homotopy Methods for Finding DC Operating Points of Nonlinear Circuits", IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, vol. 43, no. 10, pp. 824-838, Oct, 1996, PDF
- C.R. Sullivan, S.R. Sanders, "Design of Microfabricated Transformers and Inductors for High-Frequency Power Conversion", IEEE Transactions on Power Electronics, vol. 11, no. 2, pp. 228-238, March, 1996, PDF
- C.R. Sullivan, Chaofu Kao, B.M. Acker., S.R. Sanders, "Control Systems for Induction Machines with Magnetic Saturation", IEEE Transactions on Industrial Electronics, vol. 43, no. 1, pp. 142-152, Feb, 1996, PDF
- H. Hofmann, S.R. Sanders, "Speed Sensorless Vector Torque Control of Induction Machines Using a Two-Time-Scale Approach", IEEE Industry Applications Conference, vol. 1, pp. 205-212, 1996, PDF
- H. Hofmann, S.R. Sanders, "Synchronous Reluctance Motor/Alternator for Flywheel Energy Storage Systems", IEEE Power Electronics in Transportation, pp. 199-206, 1996, PDF
- C.R. Sullivan, S.R. Sanders, "Measured Performance of a High-Power-Density Microfabricated Transformer in a DC-DC Converter", IEEE Power Electronics Specialists Conference, vol. 1, pp. 287-294, 1996, PDF
- L. Daniel, C.R. Sullivan, S.R. Sanders, "Design of Microfabricated Inductors", IEEE Power Electronics Specialists Conference, vol. 2, pp. 1447-1455, 1996, PDF
- L.A. Kamas, S.R. Sanders, "Power Electronic Circuit Reliability Analysis Incorporating Parallel Simulations", IEEE Workshop on Computers in Power Electronics, pp. 45-51, 1996, PDF

- C.R. Sullivan, S.R. Sanders, "Models for Induction Machines with Magnetic Saturation of the Main Flux Path", IEEE Transactions on Industry Applications, vol. 31, no. 4, pp. 907-917, July-Aug, 1995, PDF
- H. Hofmann, S.R. Sanders, C. Sullivan, "Stator-Flux-Based Vector Control of Induction Machines in Magnetic Saturation", IEEE Industry Applications Conference, vol. 1, pp. 152-158, 1995, PDF
- B. Acker, C.R. Sullivan, S.R. Sanders , "Synchronous Rectification with Adaptive Timing Control", IEEE Power Electronics Specialists Conference, vol. 1, pp. 88-95, 1995, PDF
- C.R. Sullivan, S.R. Sanders, "Microfabrication Process for High-Frequency Power-Conversion Transformers", IEEE Power Electronics Specialists Conference, vol. 2, pp. 658-664, 1995, PDF

- B.B. Sheng, J.M. Noworolski, S.R. Sanders, "Parallel Switched Circuit Simulation on Networked Workstations", International Journal of Electronics, vol. 77, no. 5, pp. 747-762, Nov, 1994
- D.M. Wolf, M. Varghese, S.R. Sanders, "Bifurcation of Power Electronic Circuits", Journal of the Franklin Institute, vol. 331B, no. 6, pp. 957-999, Nov, 1994, PDF
- B. Acker, C.R. Sullivan, S.R. Sanders, "Current-Controlled Synchronous Rectification", IEEE Applied Power Electronics Conference, vol. 1, pp. 185-191, 1994, PDF
- Chaofu Kao, C.R. Sullivan, B. Acker, S.R. Sanders, "Induction Machine Control Systems with Magnetic Saturation", IEEE Power Electronics Specialist Conference, vol. 1, pp. 250-258, 1994, PDF
- A.J. Stratakos, S.R. Sanders, R.W. Brodersen, "A Low-Voltage CMOS DC-DC Converter for a Portable Battery-Operated System", IEEE Power Electronics Specialists Conference, vol. 1, pp. 619-626, 1994, PDF
- D.M. Wolf, S.R. Sanders, "Multi-Parameter Homotopy Methods for Finding Periodic Solutions of Nonlinear Circuits", IEEE International Symposium on Circuits and Systems, vol. 6, pp. 137-140, 1994, PDF
- D.M. Wolf, S.R. Sanders, "Multi-Parameter Homotopy for Finding Periodic Solutions of Power Electronic Circuits", IEEE 4th Workshop on Computers in Power Electronics, pp. 300-306, 1994, PDF
- L.A. Kamas, S.R. Sanders, "Reliability Analysis via Numerical Simulation of Power Electronic Circuits", IEEE 4th Workshop on Computers in Power Electronics, pp. 175-179, 1994, PDF

- L.A. Kamas, S.R. Sanders, "Parameter and State Estimation in Power Electronic Circuits", IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, vol. 40, no. 12, pp. 920-928, Dec, 1993, PDF
- A.C. Wang, S.R. Sanders, "Programmed Pulsewidth Modulated Waveforms for Electromagnetic Interference Mitigation in DC-DC Converters", IEEE Transactions on Power Electronics, vol. 8, no. 4, pp. 596-605, Oct, 1993, PDF
- S.R. Sanders, "On Limit Cycles and the Describing Function Method in Periodically Switched Circuits", IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, vol. 40, no. 9, pp. 564-572, Sept, 1993, PDF
- C.R. Sullivan, S.R. Sanders (Edited by: M. Fliess), "Modeling the Effects of Magnetic Saturation on Electrical Machine Control Systems", Nonlinear Control Systems Design, 1992, Selected Papers from the 2nd IFAC Symposium, pp. 69-76, 1993, Oxford, UK
- C.R. Sullivan, S.R. Sanders, "Microfabrication of Transformers and Inductors for High Frequency Power Conversion", IEEE Power Electronics Specialists Conference, pp. 33-41, 1993, PDF
- C.R. Sullivan, S.R. Sanders, "A Soft-Switched Constant-Frequency Square-Wave Half-Bridge DC-DC Converter", IEEE Power Electronics Specialists Conference, pp. 158-164, 1993, PDF
- R. Gurumoorthy, S.R. Sanders, "Controlling Nonminimum Phase Nonlinear Systems - The Inverted Pendulum on a Cart Example", Proceedings of the American Control Conference, vol. 1, pp. 680-685, 1993

- S.R. Sanders, G.C. Verghese, "Lyapunov-Based Control for Switched Power Converters", IEEE Transactions on Power Electronics, vol. 7, no. 1, pp. 17-24, Jan, 1992, PDF
- C.R. Sullivan, S.R. Sanders, "Models for Induction Machines with Magnetic Saturation of the Main Flux Path", IEEE Industry Applications Society Annual Meeting, vol. 1, pp. 123-131, 1992, PDF
- A. Wang, S.R. Sanders, "On Optimal Programmed PWM Waveforms for DC-DC Converters", IEEE Power Electronics Specialists Conference, vol. 1, pp. 571-578, 1992, PDF
- J.M. Noworolski, S.R. Sanders, "An Electrostatic Microresonant Power Conversion Device", IEEE Power Electronics Specialists Conference, vol. >2, pp. 997-1002, 1992, PDF
- S.R. Sanders, "Justification of the Describing Function Method for Periodically Switched Circuits", IEEE International Symposium on Circuits and Systems, vol. 4, pp. 1887-1890, 1992, PDF

- S.R. Sanders, G.C. Verghese, "Synthesis of Averaged Circuit Models for Switched Power Converters", IEEE Transactions on Circuits and Systems, vol. 38, no. 8, pp. 905-915, Aug, 1991, PDF
- S.R. Sanders, J.M. Noworolski, X.Z. Liu, G.C. Verghese, "Generalized Averaging Method for Power Conversion Circuits", IEEE Transactions on Power Electronics, vol. 6, no. 2, pp. 251-259, April, 1991, PDF
- J.M. Noworolski, S.R. Sanders, "Generalized In-Plane Circuit Averaging", IEEE Applied Power Electronics Conference, pp. 445-451, 1991, PDF
- L.A. Kamas, S.R. Sanders, "Parameter and State Estimation in Power Electronic Circuits", IEEE Power Electronics Specialists Conference, pp. 57-61, 1991, PDF
- S.R. Sanders, "Limit Cycles in Periodically Switched Circuits", IEEE International Symposium on Circuits and Systems, vol. 2, pp. 1073-1076, 1991

- A. Wang, S.R. Sanders, "Random and Programmed Pulse-Width Modulation Techniques for DC-DC Converters", IEEE International Conference on Systems Engineering, pp. 589-592, 1990, PDF
- S.R. Sanders, G.C. Verghese, "Lyapunov-Based Control for Switched Power Converters", IEEE Power Electronics Specialists Conference, pp. 51-58, 1990, PDF
- S.R. Sanders, J.M. Noworolski, X.Z. Liu, G.C. Verghese, "Generalized Averaging Method for Power Conversion Circuits", IEEE Power Electronics Specialists Conference, pp. 333-340, 1990, PDF
- S.R. Sanders, G.C. Verghese, "Synthesis of Averaged Circuit Models for Switched Power Converters", IEEE International Symposium on Circuits and Systems, vol. 1, pp. 679-683, 1990

- S.R. Sanders, "Effects of Nonzero Input Source Impedance on Closed-Loop Stability of an Unity Power Factor Converter", Proceedings of the Nineteenth International Power Conversion (PCI) Conference, pp. 91-99, 1989

- G.C. Verghese, S.R. Sanders, "Observers for Flux Estimation in Induction Machines", IEEE Transactions on Industrial Electronics, vol. 35, no. 1, pp. 85-94, Feb, 1988, PDF

- S.R. Sanders, G.C. Verghese, D.F. Cameron, "Nonlinear Control Laws for Switching Power Converters", Proceedings of the 25th IEEE Conference on Decision and Control, vol. 1, pp. 46-53, 1986

Jason Thaine Stauth and Seth R. Sanders

Conventional wireless transmitters use linear (class-A, AB) power amplifiers to perform amplitude
modulation for high-datarate standards such as 802.11a/g/n that require high spectral efficiency. In
these applications, the power amplifier (PA) typically operates with average efficiency in the range
of 5% due to strict linearity requirements [1-4]. This work is focused on new transmitter architectures
that use pulse-density modulation to perform linear amplitude modulation of the RF carrier with a
nonlinear power amplifier (PA). Advantages of this approach include high linearity for wideband
standards, high efficiency across the range of output power, and a simplified pure-digital
implementation resulting in small die area. Our approach uses deterministic (programmed) pulse density
modulation operating at the RF carrier frequency, combined with baseband ? modulation operating at
baseband frequencies. The multi-stage approach shapes quantization noise away from the signal band
allowing effective reconstruction of high peak-average power ratio (PAPR) waveforms with minimal
digital processing power. The switching PA achieves output power levels comparable to WLAN or
Bluetooth with average efficiency approaching 20% for the entire transmitter including power consumption
for the PA, PA driver, and digital processing circuitry.

More information: http://www.eecs.berkeley.edu/~jtstauth

More information: http://www.eecs.berkeley.edu/~jtstauth

Figure 1: Die photo of pulse-density modulated transmitter

- [1] A. Jerng and C. G. Sodini, "A Wideband Delta-Sigma Digital-RF Modulator for High Data Rate Transmitters," IEEE Journal of Solid State Circuits, Vol. 42, August 2007, pp. 1710-1722.
- [2] F. Wang, D. Kimball, D. Y. Lie, P. Asbeck, and L. E. Larson, "A Monolithic High-Efficiency 2.4 GHz 20 dBm SiGe BiCMOS Envelope-Tracking OFDM Power Amplifier," IEEE Journal of Solid State Circuits, Vol. 42, June 2007, pp. 1271-1281.
- [3] J. T. Stauth and S. R. Sanders, "Optimum Biasing for Parallel Hybrid Switching-Linear Regulators," IEEE Transactions on Power Electronics, Vol. 22, September 2007, pp. 1978-1985.
- [4] J. T. Stauth and S. R. Sanders, "Power Supply Rejection for Radio Frequency Amplifiers: Theory and Measurements," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, October 2007.

Michael Douglas Seeman and Seth R. Sanders

Switched-capacitor power converters have been used in IC designs for years, but the fundamentals
of the converters' operation have not been well defined. This research formally specifies the
structure of switched-capacitor converters and develops a method for easily determining the
performance of these converters. These performance metrics can be used to optimize component
values in converters as well as to compare different converter topologies. The analytical tools
developed will aid construction of several switched-capacitor circuits [1].

The first IC we built using a switched-capacitor converter is an integrated switched-capacitor DC-DC converter for use with the PicoCube project. The PicoCube system uses an average of 6 microwatts at very low duty cycles (high relative peak power) at three voltage rails. This converter will rectify an energy scavenger source and supply the three voltage rails from a single small rechargeable battery. An integrated circuit implementing this converter has been designed, manufactured, and tested. Peak efficiencies of 80% have been obtained through empirical results [2].

In the future, multi-level switched-capacitor circuits will be considered. Instead of being limited to a single conversion ratio, these enhanced topologies can efficiently be configured to produce a wide range of conversion ratios. The applications of such a converter are widespread. They have been typically used as inverters to drive motors or to create other ac waveforms. However, they can also be used to add efficient regulation to typical DC-DC applications. An IC using a multilevel switched-capacitor converter will be fabricated in future work.

The first IC we built using a switched-capacitor converter is an integrated switched-capacitor DC-DC converter for use with the PicoCube project. The PicoCube system uses an average of 6 microwatts at very low duty cycles (high relative peak power) at three voltage rails. This converter will rectify an energy scavenger source and supply the three voltage rails from a single small rechargeable battery. An integrated circuit implementing this converter has been designed, manufactured, and tested. Peak efficiencies of 80% have been obtained through empirical results [2].

In the future, multi-level switched-capacitor circuits will be considered. Instead of being limited to a single conversion ratio, these enhanced topologies can efficiently be configured to produce a wide range of conversion ratios. The applications of such a converter are widespread. They have been typically used as inverters to drive motors or to create other ac waveforms. However, they can also be used to add efficient regulation to typical DC-DC applications. An IC using a multilevel switched-capacitor converter will be fabricated in future work.

- [1] M. D. Seeman and S. R. Sanders, "Analysis and Optimization of Switched-Capacitor DC-DC Converters," IEEE COMPEL, July 2006.
- [2] M. D. Seeman, S. R. Sanders, and J. M. Rabaey, "An Ultra-Low-Power Power Management IC for Wireless Sensor Nodes," IEEE CICC, September 2007.

Vincent Wai-Shan Ng, Seth R. Sanders and Michael Douglas Seeman

This research explores the design and development of CMOS-based switched capacitor (SC) dc-dc conversion
circuitry aimed at applications traditionally addressed with the ubiquitous buck converter. The
traditional buck converter requires at least one substantial inductor and transistors with voltage
rating matched to the input source voltage, which may be costly to integrate in a submicron CMOS
technology. The traditional buck converter also suffers from low efficiency or poor power device
utilization when used in a high-conversion-ratio application. Further, buck converter efficiency
degrades rapidly in low-power modes unless additional special modes (like PFM) are enabled. SC dc-dc
converters, on the other hand, can sustain high efficiency with a high conversion ratio, and also over
a very wide load range. Moreover, SC dc-dc converters do not require any magnetic or high voltage
transistors; each power transistor needs to only block a fraction of the input voltage, thus allowing
a high voltage dc-dc converter to be built in a submicron technology with native transistors. To prove
our concept, we built a 12 V-to-1.5 V SC dc-dc converter in a 0.18 µm CMOS technology with a peak output
current of 1.5 A and a peak efficiency of 98%. This converter is ideal for the point-of-load application
in which a dc-dc converter is placed close to an associated load.

Figure 1: Efficiency versus output load condition

Mike M. He, Seth R. Sanders, and Artin Der Minassians

Two major barriers impede the widespread adoption of renewable energy technology on a large scale.
The first is high cost relative to traditional energy sources under current market conditions. The
second is that renewable sources have intermittent and fluctuating power output. A system that
offers a solution to these problems has the potential to achieve significant adoption.

One technology that has the potential to overcome these challenges is a solar thermal electric generation system with a Stirling engine and integrated energy storage. The goal of the system is to achieve a capacity cost of $1/W, generally considered a major milestone that makes solar energy cost-competitive, by employing low-cost materials, simple manufacturing, and careful design. Inherent thermal energy storage provides a means of generating continuous, stable power output. By addressing the barriers stated previously, the system has the potential to become a significant source of renewable energy.

Two low-power prototypes have been built, one a single-phase engine and the other a three-phase engine. Current work is focused on desiging a high power prototype.

One technology that has the potential to overcome these challenges is a solar thermal electric generation system with a Stirling engine and integrated energy storage. The goal of the system is to achieve a capacity cost of $1/W, generally considered a major milestone that makes solar energy cost-competitive, by employing low-cost materials, simple manufacturing, and careful design. Inherent thermal energy storage provides a means of generating continuous, stable power output. By addressing the barriers stated previously, the system has the potential to become a significant source of renewable energy.

Two low-power prototypes have been built, one a single-phase engine and the other a three-phase engine. Current work is focused on desiging a high power prototype.

Figure 1: Single Phase Stirling Engine Prototype

Figure 2: Three Phase Stirling Engine Prototype

Hanh-Phuc Le, Prof. Seth Sanders, Prof. Elad Alon

CMOS chips have evolved to operate at steadily lower supply voltages and increasing power densities,
leading to drastic reductions in the required impedance of the supply distribution network.
For example, today’s 1V, 100A microprocessors require a supply impedance of ~1mOhm, which is extremely
challenging to achieve across a broad range of frequencies. Indeed, this impedance requirement limits
the amount of current that can be efficiently delivered onto the die, limiting the ability to improve
performance by integrating additional cores. Furthermore, supporting multiple independent supply
voltages on the die (for improved power management) is currently very challenging due to the impedance
degradation associated with heavily partitioned package power planes.

In order to overcome these challenges, in this project we will study, design, and fabricate fully integrated voltage converters that maximize the overall efficiency and robustness of high-performance digital chips. To allow for multiple on-chip supply voltages and simplify the board- and package-level power delivery networks, we will focus on an architecture consisting of many distributed, fully-integrated switching regulators (for efficient conversion of a single external high-voltage supply) combined with parallel linear regulators to control the AC impedance. Since the parallel linear regulator can be designed to spend minimal power in setting the effective supply impedance [1], the switching regulator can be optimized purely for conversion efficiency. As an additional benefit, integrating the voltage converter onto the die relaxes the impedance requirements of the global supply, potentially leading to significant simplifications in the complexity of the package and PCB power distribution networks.

In order to overcome these challenges, in this project we will study, design, and fabricate fully integrated voltage converters that maximize the overall efficiency and robustness of high-performance digital chips. To allow for multiple on-chip supply voltages and simplify the board- and package-level power delivery networks, we will focus on an architecture consisting of many distributed, fully-integrated switching regulators (for efficient conversion of a single external high-voltage supply) combined with parallel linear regulators to control the AC impedance. Since the parallel linear regulator can be designed to spend minimal power in setting the effective supply impedance [1], the switching regulator can be optimized purely for conversion efficiency. As an additional benefit, integrating the voltage converter onto the die relaxes the impedance requirements of the global supply, potentially leading to significant simplifications in the complexity of the package and PCB power distribution networks.

Jason T. Stauth and Seth R. Sanders

Conventional wireless transmitters use linear (class-A, AB) power amplifiers to meet linearity
requirements for high-data rate, spectrally efficient standards such as 802.11a/g/n. In these
applications, traditional power amplifiers (PAs) operate with average efficiency in the range
of five percent, despite having the highest power consumption of any block in the radio
architecture. This significantly impacts battery life and cost for portable systems, and adds
to unnecessary power consumption in the wireless communications infrastructure.

This talk will focus on new transmitter architectures that use polar representation of the wireless signal to improve both performance and energy efficiency. The first part of the talk will discuss voltage regulation for power amplifiers, including the effects of power supply noise and the benefits of wideband regulation schemes. The second part will focus on pulse-density modulation (PDM) as a way to modulate the carrier amplitude with nonlinear power amplifier (PA) components. Advantages of this approach include high linearity for wideband standards, high efficiency across the range of output power, and a simplified pure-digital implementation resulting in small die area.

The talk will also describe the design and implementation of a highly-linear digital-polar system in 90nm CMOS. The amplitude is controlled with pulse-density modulation of the RF carrier. Phase information is provided with the RF clock. Two stages of noise shaping improve the performance of the digital transmitter. Second-order baseband sigma-delta modulation shapes in-band noise, reducing error-vector magnitude (EVM). Programmed pulse-density modulation, operating at 2.4GHz, forces much of the quantization noise power out of band, improving efficiency and spectral performance. The class-D PA achieves output power levels adequate for WLAN and Bluetooth, with peak efficiency of 38.5% at 2.4GHz, including power of the PA drivers and insertion loss of off-chip filter components. The system achieves rms EVM of 1.8-2.1% for pi/4DQPSK and 8DPSK test vectors while meeting the spectral mask and power requirements of Bluetooth 2.1+EDR.

This talk will focus on new transmitter architectures that use polar representation of the wireless signal to improve both performance and energy efficiency. The first part of the talk will discuss voltage regulation for power amplifiers, including the effects of power supply noise and the benefits of wideband regulation schemes. The second part will focus on pulse-density modulation (PDM) as a way to modulate the carrier amplitude with nonlinear power amplifier (PA) components. Advantages of this approach include high linearity for wideband standards, high efficiency across the range of output power, and a simplified pure-digital implementation resulting in small die area.

The talk will also describe the design and implementation of a highly-linear digital-polar system in 90nm CMOS. The amplitude is controlled with pulse-density modulation of the RF carrier. Phase information is provided with the RF clock. Two stages of noise shaping improve the performance of the digital transmitter. Second-order baseband sigma-delta modulation shapes in-band noise, reducing error-vector magnitude (EVM). Programmed pulse-density modulation, operating at 2.4GHz, forces much of the quantization noise power out of band, improving efficiency and spectral performance. The class-D PA achieves output power levels adequate for WLAN and Bluetooth, with peak efficiency of 38.5% at 2.4GHz, including power of the PA drivers and insertion loss of off-chip filter components. The system achieves rms EVM of 1.8-2.1% for pi/4DQPSK and 8DPSK test vectors while meeting the spectral mask and power requirements of Bluetooth 2.1+EDR.

Angel Vladimirov Peterchev, Jason Thaine Stauth, Jianhui Zhang
and Professor Seth R. Sanders

UC MICRO and National Science Foundation

UC MICRO and National Science Foundation

Digital controllers for pulse-width modulation (PWM) converters are enjoying growing popularity
due to their low power, immunity to analog component variations, ease of integration with other
digital systems, ability to implement sophisticated control schemes, and potentially faster
design process [1].

We are developing IC implementations of digital controllers for power converters that find applications in areas such as microprocessor voltage regulation modules (VRM) [2,3] and mobile device power supplies. We explore various topologies for the modules contained in a digital controller in order to provide a high-performance, low-cost solution. We have developed a very low power digital PWM (DPWM) generation module, PID control modules, and a novel low power ADC which is insensitive to switching noise and partially synthesizable. In the past year, we implemented a complete digital controller SOC for cell phone application with on-chip power switches (Figure 1) [4]. We are now investigating the implementaion of sophisticated estimation and control schemes using a combination of digital and analog processing, and special purpose analog-digital interface structures.

We are developing IC implementations of digital controllers for power converters that find applications in areas such as microprocessor voltage regulation modules (VRM) [2,3] and mobile device power supplies. We explore various topologies for the modules contained in a digital controller in order to provide a high-performance, low-cost solution. We have developed a very low power digital PWM (DPWM) generation module, PID control modules, and a novel low power ADC which is insensitive to switching noise and partially synthesizable. In the past year, we implemented a complete digital controller SOC for cell phone application with on-chip power switches (Figure 1) [4]. We are now investigating the implementaion of sophisticated estimation and control schemes using a combination of digital and analog processing, and special purpose analog-digital interface structures.

Figure 1: Block diagram of dual-mode buck converter IC

- [1] A. M. Wu, J. Xiao, D. Markovic, and S. R. Sanders, "Digital PWM Control: Application in Voltage Regulation Modules," Proc. IEEE Power Electronics Specialists Conf., Charleston, SC, June 1999.
- [2] A. V. Peterchev and S. R. Sanders, "Quantization Resolution and Limit Cycling in Digitally Controlled PWM Converters," IEEE Trans. Power Electronics, Vol. 18, No. 1, Pt. 2, January 2003, pp.301-8.
- [3] A. V. Peterchev, J. Xiao, and S. R. Sanders, "Architecture and IC Implementation of a Digital VRM Controller," IEEE Trans. Power Electronics, Vol. 18, No. 1, Pt. 2, January 2003, pp.356-64.
- [4] J. Xiao, A. V. Peterchev, J. Zhang, and S. R. Sanders, "A 4 µA Quiescent Current Dual-Mode Buck Converter IC for Cellular Phone Applications," accepted by ISSCC, San Francisco, CA, February 2004.

Angel Vladimirov Peterchev, Jason Thaine Stauth, Jianhui Zhang
and Professor Seth R. Sanders

UC MICRO and National Science Foundation

UC MICRO and National Science Foundation

The current trend in microprocessor design is characterized on the one hand by decreasing
supply voltages (~1 V), regulation windows (~100 mV), and conversion ratios (1/12), and on
the other hand by increasing supply currents (~100 A) and supply current slew rates (~300 A/us)
[1]. These trends present a challenge to the design of microprocessor voltage regulation
modules (VRMs). We are developing a control strategy that can meet these requirements, without
using an excessively large number of output capacitors.

We have analyzed the response of the buck converter under fast output current transients, and we have developed sensing and control methods for its implementation with a digital PWM controller [2]. This analysis has been done in the framework of low effective series resistance (ESR) ceramic capacitors, which are the expected choice for the next generation VRMs. We have further explored the effect of power train parameter variations on the current matching among the phases of the converter [2].

We are currently working on discrete and IC implementations of a VRM controller with very fast response based on load current estimation and feed-forward. We are also considering IC implementations of advanced parameter estimation schemes.

We have analyzed the response of the buck converter under fast output current transients, and we have developed sensing and control methods for its implementation with a digital PWM controller [2]. This analysis has been done in the framework of low effective series resistance (ESR) ceramic capacitors, which are the expected choice for the next generation VRMs. We have further explored the effect of power train parameter variations on the current matching among the phases of the converter [2].

We are currently working on discrete and IC implementations of a VRM controller with very fast response based on load current estimation and feed-forward. We are also considering IC implementations of advanced parameter estimation schemes.

- [1] A. V. Peterchev and S. R. Sanders, "Low Conversion Ratio VRM Design," Proc. IEEE Power Electronics Specialists Conf., Cairns, Australia, June 2002.
- [2] A. V. Peterchev, J. Xiao, and S. R. Sanders, "Architecture and IC Implementation of a Digital VRM Controller," IEEE Transactions on Power Electronics, Vol. 18, No. 1, Pt. 2, January 2003, pp.356-64.

Angel Vladimirov Peterchev, Jason Thaine Stauth, Jianhui Zhang
and Professor Seth R. Sanders

UC MICRO and National Science Foundation

UC MICRO and National Science Foundation

Digital control has drawn increased attention to the area of pulse-width modulation (PWM)
converters. Digital controllers (Figure 1) are attractive for their low power dissipation,
immunity to analog component variations, compatibility with digital systems, and ability to
implement sophisticated control schemes [1].

In this project, we have addressed system issues that are unique to digital control, such as the impact of the signal quantization in the feedback control loop. We have developed a set of conditions necessary for the elimination of limit cycles in digital controllers [2]. Further, we have analyzed and successfully used controlled digital dither to increase the effective resolution of digital PWM (DPWM) modules, while minimizing the dither ripple incurred on the regulated output voltage [2].

We have demonstrated implementations of the above-mentioned techniques with an FPGA-controlled voltage regulation module (VRM) for microprocessor applications [3], and a low power IC controller for cell phone applications [4].

We are currently aiming to develop online power optimization techniques for a digital PWM controller. The idea is to minimize the power dissipation of the converter by dynamically adjusting parameters such as the synchronous rectification dead time [5] and the current sharing in multi-phase converters. This work can result in robust, self-optimizing power converters, and can offer new approaches to automatic mode switching (e.g., between continuous and discontinuous conduction mode in PWM converters). The ability of the digital controller to implement complex computation algorithms offers a major advantage for this application.

In this project, we have addressed system issues that are unique to digital control, such as the impact of the signal quantization in the feedback control loop. We have developed a set of conditions necessary for the elimination of limit cycles in digital controllers [2]. Further, we have analyzed and successfully used controlled digital dither to increase the effective resolution of digital PWM (DPWM) modules, while minimizing the dither ripple incurred on the regulated output voltage [2].

We have demonstrated implementations of the above-mentioned techniques with an FPGA-controlled voltage regulation module (VRM) for microprocessor applications [3], and a low power IC controller for cell phone applications [4].

We are currently aiming to develop online power optimization techniques for a digital PWM controller. The idea is to minimize the power dissipation of the converter by dynamically adjusting parameters such as the synchronous rectification dead time [5] and the current sharing in multi-phase converters. This work can result in robust, self-optimizing power converters, and can offer new approaches to automatic mode switching (e.g., between continuous and discontinuous conduction mode in PWM converters). The ability of the digital controller to implement complex computation algorithms offers a major advantage for this application.

Figure 1: Block diagram of a digitally controlled PWM converter

- [1] A. M. Wu, J. Xiao, D. Markovic, and S. R. Sanders, "Digital PWM Control: Application in Voltage Regulation Modules," Proc. IEEE Power Electronics Specialists Conf., Charleston, SC, June 1999.
- [2] A. V. Peterchev and S. R. Sanders, "Quantization Resolution and Limit Cycling in Digitally Controlled PWM Converters," IEEE Transactions on Power Electronics, Vol. 18, No. 1, Pt. 2, January 2003, pp.301-8.
- [3] A. V. Peterchev, J. Xiao, and S. R. Sanders, "Architecture and IC Implementation of a Digital VRM Controller," IEEE Transactions on Power Electronics, Vol. 18, No. 1, Pt. 2, January 2003, pp.356-64.
- [4] J. Xiao, A. V. Peterchev, J. Zhang, and S. R. Sanders, "A 4 µA Quiescent Current Dual-Mode Buck Converter IC for Cellular Phone Applications," accepted for Int. Solid State Circ. Conf., 2004
- [5] B. Acker, C. R. Sullivan, and S. R. Sanders, "Synchronous Rectification with Adaptive Timing Control," Proc. IEEE Power Electronics Specialists Conf., Atlanta, GA, June 1995

Mervin John and Prof. Seth R. Sanders

A representative wireless sensor node contains sensing functions (eg, temperature, pressure, acceleration, strain, chemical, etc.), wireless communication capability, supervisory management, an energy/power source, energy storage, and associated energy/power conversion and management functionality. This research explores the analysis and design issues surrounding integrated CMOS based power conversion and management techniques required in such a wireless sensor device. Fully-integrated switched capacitor DC-DC converters, with no external magnetics, are ideally suited for these types of centimeter and millimeter-scale applications. This research explores techniques for achieving high efficiency over a wide power range (~1uA->~10mA) using minimal die area for the on-chip capacitors.

Jason Poon, Prof. Costas Spanos, Prof. Seth R. Sanders

The proliferation of power electronics has enabled rapid adoption of more efficient and capable energy conversion technologies. Today, the power infrastructure in smart buildings, data centers, and distribution networks all rely on power electronics devices. A paramount challenge in each of these application areas is the need for highly robust and fault tolerant power electronics systems.

This project aims to develop an analysis, design, and experimental implementation of a fault diagnosis method for switching power converters using a model-based estimator approach. The fault diagnosis method enables efficient detection and identification of component and sensor faults, and is implemented on the same computation platform as the control system. The model-based estimator operates in parallel with the switching power converter, and generates an error residual vector that can be used to detect and identify particular component or sensor faults. Moreover, the proposed fault diagnosis design and analysis methods are applicable to a broad class of converter topologies and fault types.

This project aims to develop an analysis, design, and experimental implementation of a fault diagnosis method for switching power converters using a model-based estimator approach. The fault diagnosis method enables efficient detection and identification of component and sensor faults, and is implemented on the same computation platform as the control system. The model-based estimator operates in parallel with the switching power converter, and generates an error residual vector that can be used to detect and identify particular component or sensor faults. Moreover, the proposed fault diagnosis design and analysis methods are applicable to a broad class of converter topologies and fault types.

- [1] Jason Poon, Ioannis C. Konstantakopoulos, Costas Spanos, Seth R. Sanders, "Real-Time Model-Based Fault Diagnosis for Switching Power Converters," Proc. 2015 IEEE Applied Power Electronics Conference (APEC), Charlotte, NC. March 2015.

Mervin John, Yongjun Li, Prof. Seth R. Sanders

Power has emerged as fundamental concern in the design of modern mobile devices with an increasing need for compact, fully integrated power converters in these devices. Switched-capacitor (SC) based designs have shown great promise in recent research due to the favorable high energy density of on-chip capacitors. However, power density in standard switched capacitor converters is limited by the available capacitor density of a given technology, along with frequency of operation and a trade-off with efficiency. The latter trade-off with efficiency arises from a fundamental charge-sharing loss associated with SC designs. In our proposed Resonant Switched-Capacitor (ResSC) architecture we introduce a small inductor in series with the flying capacitor to reduce this intrinsic charge-sharing loss and achieve higher power densities for fully integrated DC-DC converters.

Our proposed design targets Li-Ion battery voltages in the range of 3.4V to 4.2V with a programmable 0.8V to 1.2V output range. We have implemented a Resonant Switched Capacitor (ResSC) DC-DC converter with an expected simulated efficiency of over 75% in the target output voltage range at an expected power density of 1.3W/mm^2. 8 Phases of the nominal 4:1 conversion ratio topology are interleaved for reduced ripple voltages with all capacitors implemented on-chip using MOM or MOS-based designs. Inductors are implemented using standard bondwires. The nominal switching frequency for above resonance operation is in the range of 250MHz to 350MHz.

Our proposed design targets Li-Ion battery voltages in the range of 3.4V to 4.2V with a programmable 0.8V to 1.2V output range. We have implemented a Resonant Switched Capacitor (ResSC) DC-DC converter with an expected simulated efficiency of over 75% in the target output voltage range at an expected power density of 1.3W/mm^2. 8 Phases of the nominal 4:1 conversion ratio topology are interleaved for reduced ripple voltages with all capacitors implemented on-chip using MOM or MOS-based designs. Inductors are implemented using standard bondwires. The nominal switching frequency for above resonance operation is in the range of 250MHz to 350MHz.

Achintya Madduri, Jason Poon, Prof. Seth R. Sanders

This project involves the design and experimental validation of a scalable dc microgrid architecture for rural electrification. The microgrid design has been driven by field data collected from Kenya and India. The salient features of the microgrid are distributed voltage control and distributed storage, which enable developed world grid cost parity. We have calculate that the levelized cost of electricity (LCOE) for the proposed dc microgrid system will be less than $0.40 per kW-hr. We also have experimental results from a locally installed dc microgrid prototype that demonstrate the steady state behavior, the perturbation response, and the overall efficiency of the system. The experimental results demonstrate the suitability of the presented dc microgrid architecture as a technically advantageous and cost effective method for electrifying emerging regions.

- [1] P. Achintya Madduri, Jason Poon, Javier Rosa, Matthew Podolsky, Eric Brewer, Seth R. Sanders, "A Scalable DC Microgrid Architecture for Rural Electrification in Emerging Regions," Proc. 2015 IEEE Applied Power Electronics Conference (APEC), Charlotte, NC. March 2015.
- [2] P. Achintya Madduri, Javier Rosa, Eric A. Brewer, Seth R. Sanders and Matthew Podolsky, "Design and Verification of Smart and Scalable DC Microgrids for Emerging Regions," Proc. 2013 IEEE Energy Conversion Congress and Exposition (ECCE), Denver, CO. September 2013.

Daniel Gerber, Prof. Seth R. Sanders

Over the next several decades, LED bulbs will replace incandescent and CFL bulbs in residential lighting. With this new technology comes the demand for compact and highly efficient light bulb drivers. Modern commercially available LED bulbs often contain a discrete component driver with expensive magnetics. This project will offer an alternative driver topology that can be integrated so as to save on cost and size, while maintaining efficiency. In addition, this driver has the ability to actively cancel the 120 Hz ripple from the line, thus removing flicker in the LEDs.