Article
Engineering, Electrical & Electronic
Yue Zhong, Wing-Hung Ki, Junmin Jiang
Summary: This paper proposes a new 6-phase, 3 interleaving cells bridged, fully integrated 1/4x switched-capacitor converter (SCC) with improved current density. Capacitor bridging and phase expansion techniques are introduced to solve idle capacitor and area overhead issues. A phase clamp technique is also proposed to address drain and source flipping problems.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2022)
Article
Engineering, Electrical & Electronic
Chuang Wang, Yan Lu, Rui P. Martins
Summary: This paper presents a single-stage tri-path buck converter with reduced inductor current and self-balanced flying capacitor voltage. The proposed converter utilizes capacitor paths to decrease conduction loss and realizes a low voltage conversion ratio. Additionally, it eliminates the need for extra gate drivers by reusing the flying capacitor voltages.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Ziyu Xia, Kishalay Datta, Jason T. Stauth
Summary: This article presents a state-space analysis of hybrid topologies to predict and control system dynamics, addressing the voltage imbalance issue in hybrid and resonant switched-capacitor converters.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Automation & Control Systems
Javad Ebrahimi, Hamidreza Karshenas
Summary: This article introduces a four-level single flying capacitor converter (4L-SFCC) topology and a new modulation technique. The topology features only one flying capacitor per phase, while the modulation technique ensures capacitor voltage balancing. Simulation results validate the performance of the proposed converter.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2021)
Article
Automation & Control Systems
Mario Alberto Gonzalez Vazquez, Fernando Salinas Salinas, Miguel Francisco Escalante Gutierrez
Summary: This paper presents an estimation method for capacitor and input voltages in Flying Capacitor Multilevel Converters (FCMC) using output current and voltage measurements. The estimation process is represented as a Petri Net, simplifying hardware and allowing real-time implementation in high-level systems.
Article
Engineering, Electrical & Electronic
Junmin Jiang, Xun Liu, Wing-Hung Ki, Philip K. T. Mok, Yan Lu
Summary: This brief tutorial presents recent circuit design techniques for high efficiency fully-integrated switched-capacitor converters, highlighting design challenges and tradeoffs among topology generation, parasitic loss reduction, clock generation and distribution, and close-loop regulation. Circuit techniques and design guidelines are suggested.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2021)
Article
Automation & Control Systems
Li Ding, Yuzhuo Li, Yun Wei Li
Summary: This article introduces and investigates the three-phase flying-capacitor-clamped CSC for the first time. A novel space vector modulation method is proposed. Simulation and experimental results demonstrate the superior dc-link power quality and CMV performance compared with the traditional three-phase CSC topology.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Li Ding, Yuzhuo Li, Yun Wei Li
Summary: This article proposes a new type of CSC topology using isomorphic theory, which reduces the dc-side dv/dt, improves the common-mode voltage, and increases the withstand voltage of the converter by utilizing ac-type flying capacitors and alternative commutation loops in each phase leg.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Zichao Ye, Yutian Lei, Zitao Liao, Robert Carl Nikolai Pilawa-Podgurski
Summary: This article investigates the origins of voltage imbalance in practical implementations of flying capacitor multilevel (FCML) converters and presents corresponding circuit analysis and solutions to improve balancing. The study demonstrates that the source impedance and input capacitance can greatly affect capacitor balancing and that an FCML converter with an even number of levels has stronger immunity to disturbances. It is also found that gate signal propagation delay mismatch and variations in on-state resistance among switches have a relatively small impact on capacitor voltage balancing.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Computer Science, Information Systems
Sangmin Song, Minsung Kim, Sung-Yun Park
Summary: In this study, a high-power conversion efficiency on-chip switched-capacitor DC-DC step-up converter is proposed for fully implantable neural interfaces. It operates with low power consumption from energy harvesting. By implementing a phase-reduced soft-charging technique, the efficiency of the converter is improved under light loads and wide variations of voltage-conversion ratio, which is common in ultra-low-power fully implantable systems.
Article
Engineering, Electrical & Electronic
Xuetao Zeng, Xuan Zhang, Lei Yao, Ning Xue
Summary: This paper presents the design and implementation of an energy efficient high-voltage pulse generator for MEMS capacitive sensors and actuators. By employing methods such as dynamic output impedance and load energy recycling, the circuit achieves a relatively high end-to-end energy efficiency.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2021)
Article
Engineering, Electrical & Electronic
Mads Graungaard Taul, Nathan Pallo, Andrew Stillwell, Robert C. N. Pilawa-Podgurski
Summary: The flying-capacitor multilevel converter is a promising topology with reduced switch voltage rating, but vulnerable to device failure during short-circuit conditions. While there is research interest in fault-tolerant operation and balancing, there is limited focus on short-circuit fault analysis of the converter; this article presents a comprehensive model describing the large-signal short-circuit switching behavior of a general N-level flying-capacitor multilevel converter, aimed at providing conservative design guidelines for practicing engineers.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Computer Science, Information Systems
Piotr Czyz, Panteleimon Papamanolis, Francesc Trunas Bruguera, Thomas Guillod, Florian Krismer, Vladan Lazarevic, Jonas Huber, Johann W. Kolar
Summary: By using model predictive control (MPC) and cell multiple switching (CMS) approaches, we have proposed a concept for load-independent flying capacitor voltage balancing in quasi-2-level (Q2L) flying-capacitor converters (FCC), ensuring equal voltage sharing among switches and improving overall performance.
Article
Engineering, Electrical & Electronic
Peng Fang
Summary: This article presents a method for achieving high efficiency in converters over a wide voltage range. By reconfiguring the flying capacitor multilevel power conversion input stage, the voltage across key components can be maintained relatively constant, allowing for optimized component selection and operation.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Automation & Control Systems
Fanguang Shao, Kai Yao, Xinbo Ruan, Renzheng Feng, Lujun Ren
Summary: In this article, a 4:1 switched capacitor converter is proposed. It achieves a higher efficiency compared to the Dickson 4:1 converter by reducing the voltage of flying capacitors, thus mitigating the effect of dc bias on multilayer ceramic capacitors (MLCCs). This converter is suitable for applications with limited volume, such as mobile phone fast charging. A 20-V to 5-V prototype with 24 X7R MLCCs in 0805 package is built, and it has a 1.7% higher efficiency than the Dickson 4:1 and 1.1% higher than the series-parallel 4:1 at 16-A output current.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Junmin Jiang, Xun Liu, Cheng Huang, Wing-Hung Ki, Philip K. T. Mok, Yan Lu
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2020)
Article
Engineering, Electrical & Electronic
Yasu Lu, Fan Yang, Feng Chen, Philip K. T. Mok
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2020)
Article
Engineering, Electrical & Electronic
Juninin Jiang, Xun Liu, Wing-Hung Ki, Philip K. T. Mok, Yan Lu
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2020)
Article
Engineering, Electrical & Electronic
Yuan Gao, Lisong Li, Kwun-Hok Chong, Philip K. T. Mok
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2020)
Article
Engineering, Electrical & Electronic
Feng Chen, Yasu Lu, Philip K. T. Mok
Summary: This article introduces a digitally assisted analog low-dropout (DA-ALDO) regulator, which achieves tight regulation, wide load current range, area-efficient power transistor utilization, and fast transient speed. The regulator utilizes an analog control scheme in steady state and invokes a digital control scheme only during transient events for speed enhancement, quiescent current reduction, and switching noise suppression. The DA-ALDO is fabricated in a 65-nm CMOS process, achieving 30-muV/mA load regulation with a 120-muA quiescent current, and demonstrating undershoot/overshoot and settling time with a 450-mA/100-ns load current step.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2021)
Article
Engineering, Electrical & Electronic
Junmin Jiang, Xun Liu, Wing-Hung Ki, Philip K. T. Mok, Yan Lu
Summary: This brief tutorial presents recent circuit design techniques for high efficiency fully-integrated switched-capacitor converters, highlighting design challenges and tradeoffs among topology generation, parasitic loss reduction, clock generation and distribution, and close-loop regulation. Circuit techniques and design guidelines are suggested.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2021)
Article
Engineering, Electrical & Electronic
Kwun-Hok Chong, Yuan Gao, Philip K. T. Mok
Summary: The brief introduces a customized AC hybrid LED driver for high nominal range applications using average current control, with a special design approach to achieve high efficiency and power factor while avoiding photometric flicker under 230V-AC, 50Hz input. The driver is fabricated with a 0.18μm, 700-V ultra-high voltage CMOS process, delivering 17-watt power to LEDs with peak efficiency over 94% and power factor greater than 0.92.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2021)
Article
Engineering, Electrical & Electronic
Qin Kuai, Qiping Wan, Philip K. T. Mok
Summary: A dual-frequency dual-input-dual-output interface based on a reconfigurable switching converter is proposed for thermoelectric energy harvesting. The interface can automatically switch between energy-harvesting and energy-recycling modes based on load conditions. Real-time zero-current detection method is used to instantaneously and accurately turn off power switches. The research achieves high efficiency energy harvesting and recycling within specific input voltage ranges.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2021)
Article
Engineering, Electrical & Electronic
Di Luo, Yuan Gao, Philip K. T. Mok
Summary: This paper presents a gate driver for a GaN-based half-bridge structure operating in a buck converter with input voltage >40 V or a boost converter with output voltage >30 V. The gate driver utilizes two 500 pF on-chip capacitors to construct three-level gate drivers, providing a near-$V_{{DD}}$ negative voltage for the rectifier switch gate to eliminate induced pulses on the gate. The dead time controller adjusts the gate signal delay of the rectifier switch based on the slope of $V_{X}$, achieving near-optimal zero-voltage switching with <3 ns deviation. The GaN driver is manufactured using a 0.18-μm BCD process. The efficiencies of the buck and boost converters are improved by 8.33% and 6.87% at light load, respectively, due to the dead-time control. The peak efficiencies of the 20 V-12 V and 12 V-18 V conversions are 86.37% and 84.39%, respectively.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Qin Kuai, Ho-Yin Leung, Qiping Wan, Philip K. T. Mok
Summary: This study introduces an auto-polarity thermoelectric energy-harvesting interface circuit that uses a single-inductor boost/buck-boost hybrid converter for power conversion efficiency. It employs an efficient scheme of frequency selection and MPPT, along with a digital ZCD technique and cold startup method to handle different input voltage scenarios.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2022)
Article
Engineering, Electrical & Electronic
Sijie Pan, Philip K. T. Mok
Summary: This work presents a 25 MHz adaptive on/off-time-controlled three-level buck converter with a fast reference tracking speed and high light load efficiency. By introducing a real-time calibration loop on the flying capacitor voltage, the balancing error is effectively reduced. The converter demonstrates fast tracking speed when implementing a specific step, and achieves accurate DCM operation under light load conditions.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Xun Liu, Junmin Jiang, Cheng Huang, Philip K. T. Mok
Summary: This article provides a brief tutorial on designing a high efficiency envelope-tracking supply modulator using recent techniques. It discusses the design challenges for 5G communication applications and explores detailed techniques such as topology derivation, multi-level and fast-speed switching converter design considerations, voltage step-up and -down function implementations, linear amplifier bandwidth improvements, and measurement setups, offering design guidelines and considerations.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2022)
Article
Engineering, Electrical & Electronic
Feng Chen, Yasu Lu, Philip K. T. Mok
Summary: This paper presents a rigorous transfer function analysis of the power supply rejection ratio (PSRR) of low-dropout (LDO) regulators and the LDO with the feed-forward ripple cancellation (FFRC) scheme. The proposed model and the analytical results serve as the theoretical foundation of the design of high-PSRR LDOs.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Xun Liu, Junmin Jiang, Cheng Huang, Philip K. T. Mok
Summary: This paper provides a detailed analysis of the loop gain and stability of hybrid power amplifier supply modulators. The study examines the design considerations, including the relationship between voltage and current loops, the importance of current loop compensation for stability and bandwidth improvement, and the impact of the current loop on system stability and efficiency. The analysis is supported by simulation results, and a hybrid supply modulator has been successfully designed and fabricated.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2022)
Article
Computer Science, Hardware & Architecture
Siu-Hong Wu, Xun Liu, Qiping Wan, Qin Kuai, Ying-Khai Teh, Philip K. T. Mok
Summary: This study introduces a boost converter with ultralow-voltage time-domain control for thermoelectric generators, achieving maximum power point tracking with a minimum open-circuit voltage of 80 mV and a peak efficiency of 72.1%.
IEEE SOLID-STATE CIRCUITS LETTERS
(2021)