An On-Chip Cockcroft-Walton Switched-Capacitor Converter Using Split-Phase Control for Improved Soft-Charging with 9.72 Conversion Gain

DOI: https://doi.org/10.23075/jicas.2022.8.3.007
Keywords: Cockcroft-Walton (C-W) topology, Split-phase control, Soft-Charging, Switched-Capacitor(SC) Converter

Abstract

This work proposes a switched-capacitor (SC) converter for high voltage generation required for medical ultrasound imaging system. Among high voltage generation circuits, an inductor-based DC-DC converter generates a high output voltage from low input voltage by storing magnetic energy in the inductor. Unlike the inductor-based DC-DC boost converter that employs magnetic energy storage, SC converter employs only switches and capacitors. Inductor-based DC-DC boost converter requires a bulky power inductor and high voltage (HV) devices that requires a large area. Therefore, SC converter is quite advantageous for the implementation of an integrated circuit (IC) in terms of area. Besides, SC converter has relatively less conduction loss than inductive DC-DC boost converter. For these reasons, the SC converter is suitable for generating high voltages in ICs. However, the power loss of the SC converter can be analyzed by dividing it into three major losses. This work analyzes these losses and applies techniques to reduce them in order to improve the conversion gain and power efficiency. As a result, an on-chip Cockcroft-Walton SC converter using split-phase control for improved soft-charging with conversion gain 9.72 and power efficiency 70.1% suitable for the portable ultrasound imaging device is implemented. However, the measurement results of this study were worse than the simulation results due to mismatched control clock.

Author Biographies

Jong Myeong Lee, Korea Advanced Institute of Science and Technology

Jong Myeong Lee received the B.S.degrees in electrical engineering from Sung Kyun Kwan University (SKKU), Suwon, Korea, in 2018 and received the M.S degree in electrical engineering from Korea Advanced Institute of Science and Technology (KAIST), Deajeon, Korea in 2021. His research interest includes power management integrated circuit (IC) designs, especially switched-capacitor converter for biomedical devices.

Min Kyu Je, Korea Advanced Institute of Science and Technology

Min Kyu Je (S’97-M’03-SM’12) received the M.S. and Ph.D. degrees, both in Electrical Engineering and Computer Science, from Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, in 1998 and 2003, respectively. In 2003, he joined Samsung Electronics, Giheung, Korea, as a Senior Engineer and worked on multi-mode multi-band RF transceiver SoCs for GSM / GPRS / EDGE / WCDMA standards. From 2006 to 2013, he was with Institute of Microelectronics (IME), Agency for Science, Technology and Research (A*STAR), Singapore. He worked as a Senior Research Engineer from 2006 to 2007, a Member of Technical Staff from 2008 to 2011, a Senior Scientist in 2012, and a Deputy Director in 2013. From 2011 to 2013, he led the Integrated Circuits and Systems Laboratory at IME as a Department Head. In IME, he led various projects developing low-power 3D accelerometer ASICs for high-end medical motion sensing applications, readout ASICs for nanowire biosensor arrays detecting DNA/RNA and protein biomarkers  for  point-of-care diagnostics, ultra-low-power sensor node SoCs for continuous real-time wireless health monitoring, and wireless implantable sensor ASICs for medical devices, as well as low-power radio SoCs and MEMS interface/control SoCs for consumer electronics and industrial applications. He was also a Program Director of Neuro Devices Program under A*STAR Science and Engineering Research Council (SERC) from 2011 to 2013, and an Adjunct Assistant Professor in the Department of Electrical and Computer Engineering at National University of Singapore (NUS) from 2010 to 2013. He was an Associate Professor in the Department of Information and Communication Engineering at Daegu Gyeongbuk Institute of Science and Technology (DGIST), Korea from 2014 to 2015. Since 2016, he has been an Associate Professor in the School of Electrical Engineering at Korea Advanced Institute of Science and Technology KAIST), Korea. His main   research areas are advanced IC platform development including smart sensor interface ICs and ultra-low-power    wireless communication ICs, as well as microsystem    integration leveraging the advanced IC platform for   emerging applications such as intelligent miniature biomedical devices, ubiquitous wireless sensor nodes, and future mobile devices. He is an author of 5 book chapters, and has more than 260 peer-reviewed international conference and journal publications in the areas of sensor interface IC, wireless IC, biomedical microsystem, 3D IC, device modeling and nanoelectronics. He also has more than 40 patents issued or filed. He hasserved on the Technical Program Committee and Organizing Committee for various international conferences, symposiums and   workshops including IEEE International Solid-State Circuits Conference (ISSCC), IEEE Asian Solid-State Circuits Conference (A-SSCC) and IEEE Symposium on VLSI Circuits (SOVC).

Homepage : https://impact.kaist.ac.kr/

Published
2022-06-30
How to Cite
Lee, J. M., & Je, M. K. (2022). An On-Chip Cockcroft-Walton Switched-Capacitor Converter Using Split-Phase Control for Improved Soft-Charging with 9.72 Conversion Gain. Journal of Integrated Circuits and Systems, 8(3). https://doi.org/10.23075/jicas.2022.8.3.007
Issue
Vol 8 No 3 (2022)
Section
Articles