Redistribution Loss and Integrated Charge Pump Design

by Professor Wing-Hung Ki, Associate Professor, Department of Electronic & Computer Engineering, HKUST

 :  11 May 2005 (Wed)
 :  4:00pm - 5:00pm
Venue  :  Cheung On Tak Lecture(LT-E), HKUST.

Charge pumps have been proposed and designed for 30 years, and many research works were published on the analysis and enhancement of their efficiency. We learn from high school that when two capacitors with different voltages are connected in parallel, energy is lost. We coined this loss the charge redistribution loss, or simply, redistribution loss. Interesting enough, of all the paper published on efficiency analysis, only a handful mentioned about this loss, but nevertheless, the topic was only touched upon lightly. Instead, some mentioned conduction loss by multiplying the switch resistance and the load current, but in fact, if every charge transfer is complete, which is the case for high efficiency charge pumps, conduction loss cannot be clearly defined. For a linear charge pump with many stages, some put down pages of charge equations, but readers still have no clue on how they were related to design. This talk is developed with two objectives in mind: (1) to investigate charge redistribution loss in depth, especially how it is related to the efficiency of charge pumps; and (2) to find the optimal assignment for all capacitors based on the equations derived.

Dr Ki received his BSc degree (1984) from the University of California, San Diego (major: electronic systems; minors: operations research, queuing theory), the MSc degree (1985) from the California Institute of Technology , Pasadena, the Engineer Degree (1990) and the PhD degree (1995) from the University of California, Los Angeles (major: integrated circuits & systems; minors: communications, semiconductor physics; thesis: "Gain- and Offset- Compensated Switched-Capacitor Circuits", June 1995), all in electrical engineering. From 1985 to 1986, he was a research assistant in the Power Electronics Group (PEG) of Caltech, helping to develop the software SCAMP (Switching Converter Analysis & Measurement Program). He joined Micro Linear Corporation, San Jose, in 1992 as a Senior Design Engineer in the Department of Power and Battery Management, working on the design of power converter controllers until joining HKUST in 1995. Ki is the recipient of the Asia Innovator Award of the Year 1997-1998 granted by EDN Asia.


*** All are Welcome ***