CHING-JAN CHEN

Prof. CHING-JAN CHEN

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Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 March 2012 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
YLYu-Cheng Lin
Yu-Cheng Lin
CCCHING-JAN CHEN
CHING-JAN CHEN
DCDan Chen
Dan Chen
BWBrian Wang
Brian Wang
In recent years, there has been a growing trend of mandating high-power conversion efficiency, for not only the heavy-load but also the light-load conditions. To achieve this purpose, a ripple-based constant on-time (RBCOT) control for dc-dc converters has received wide attentions because of its natural characteristic of switching frequency reduction under the light-load condition. However, a RBCOT control suffers from an output-voltage offset problem and a subharmonic instability problem. In this paper, a modified RBCOT buck converter circuit is proposed to solve both problems. The circuit uses the concept of virtual inductor current to stabilize the feedback, and an offset-cancellation circuit to eliminate the output dc offset. The modified circuit can be fabricated into an integrated circuit (IC) without adding any pin compared to conventional circuits. A control model based on describing function is developed for the modified converter. The small-signal characteristics and design criteria to meet stability are derived. From the model, it is also found out that it is much easier to accomplish adaptive voltage positioning using the proposed modified RBCOT scheme compared to a conventional constant-frequency controller. Simulation and experimental results are given to verify the proposed scheme.
1 March 2011
Verified
Conference Paper
Closed access
CCCHING-JAN CHEN
CHING-JAN CHEN
DCDan Chen
Dan Chen
CTChih-Wei Tseng
Chih-Wei Tseng
CTCheng-Te Tseng
Cheng-Te Tseng
YCYu-Wei Chang
Yu-Wei Chang
KWKoCheng Wang
KoCheng Wang
Ripple-based constant on-time (RBCOT) control has found applications because of its fast load transient response, small component count, and good light-load efficiency. However, this control scheme often encounters instability issue of subharmonic oscillation when ceramic capacitors are used for converter output filter capacitors. In the paper, a novel RBCOT control with virtual inductor current ripple was proposed to alleviate this problem. The novel control scheme improves system stability of RBCOT control without adding extra pins and converter components in IC implementation. Thus resulting in less component count and controller cost. Describing function method was used to derive the model and stability criterion of the proposed scheme, including the effect of delay-time. The scheme was implemented in an IC. Simulation and experimental results also confirm the proposed concept and the accuracy of the stability criterion developed.
16 June 2017 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
CCChing-Hsiang Cheng
Ching-Hsiang Cheng
CCCHING-JAN CHEN
CHING-JAN CHEN
SWShinn-Shyong Wang
Shinn-Shyong Wang
Flyback converter is widely used in low-power adaptor applications. To achieve high efficiency for the entire load range of operations, the variable-frequency peak-current-mode (VFPCM) control is often used in the flyback converter to reduce switching frequency at light load. Since there is no small-signal model being developed for the VFPCM control to overcome the unstable problem in a wide range of operations, the present study proposes a novel, accurate small-signal model for VFPCM control operated in continuous-conduction mode. Control behavior and design are analyzed and compared with constant-frequency peak-current-mode control to give engineers insight. A control IC and a flyback converter are built for the experimental validation of the proposed model. Experimental and simulation results verify the proposed model.
29 August 2019 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
YLYu-Chen Li
Yu-Chen Li
CCCHING-JAN CHEN
CHING-JAN CHEN
CTChieh-Ju Tsai
Chieh-Ju Tsai
A constant on-time buck converter with analog time-optimized on-time control (OTC) is proposed in this paper to achieve fast load-current step-up transient response for high slew-rate loads. The proposed control firstly implements a constant on-time converter embedded with analog time-optimized OTC and solves the prior art issues such as poor light-load efficiency, high quiescent current, and the dependence on the power stage parameters of OTC. The body diode control (BDC), which minimizes overshoot with simple logic and capacitor-current sensor, is proposed for load current step-down. The proposed control was implemented into an integrated circuit (IC) using 0.18um CMOS process with a chip area of 1.423 $\text{mm}^2$ , where OTC only occupies 0.054 $\text{mm}^2$ . The simulation results show 51.3% and 55.5% reductions of voltage deviation after enabling proposed control functions at load step-up and step-down, respectively. Measurement results show that the undershoot of output voltage improves 52.4% after enabling OTC for a 0.84A load step-up.
29 September 2009 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
CHChun-Shih Huang
Chun-Shih Huang
DCDan Chen
Dan Chen
CCCHING-JAN CHEN
CHING-JAN CHEN
KLKwang H. Liu
Kwang H. Liu
A single-inductor dual-output (SIDO) buck converter has recently found applications in hand-held battery-powered electronic devices. The circuit operation and the functional interdependencies among basic converter parameters such as dc voltage gains, transistor duty cycles, and load current levels are much more complicated than those of the single-output counterpart. In this paper, a rigorous analysis was conducted to develop dc equations in steady-state operation for SIDO converters. More importantly, from the analysis results, a possibility of a new mode of operation, dubbed “mix-voltage” operation, will be pointed out. In the so-called “mix-voltage” operation, the converter is capable of working even when the input voltage is lower than one of the two output voltages. In the past, a SIDO buck converter has been used for providing “pure-buck” outputs, i.e., both output voltages are lower than the input voltage. Therefore, this possibility not only opens up new applications but also extends the operating battery range in existing applications. Experimental results confirmed the dc equations and the “mix-voltage” conversion of SIDO buck converters.
16 March 2022 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
CCCHING-JAN CHEN
CHING-JAN CHEN
PWPin-Ying Wang
Pin-Ying Wang
SLSheng-Teng Li
Sheng-Teng Li
Yen-Ming ChenYen-Ming Chen
Yen-Ming Chen
YCYu-Cheng Chang
Yu-Cheng Chang
This paper proposes a high-frequency integrated gate driver for gallium nitride (GaN) synchronous buck converter. The proposed adaptive bang-bang dead-time control minimizes dead-time at any load condition. Thus, it mitigates the excessive power loss caused by GaN device reverse conduction in high-frequency applications. The proposed charge sharing bootstrap circuit ensures sufficient gate overdrive voltage with reduced chip area. Fabricated in a TSMC 0.25-m BCD process, the driver integrated circuit (IC) enabled GaN-based buck converter to operate at 10 MHz switching frequency with minimal dead-time to as low as 0.4 ns under light load and heavy load conditions. Compared with fixed dead-time control, the proposed work improves around 5% efficiency under heavy load condition. The fully integrated bootstrap circuit with 100 pF and 60 pF (HV) capacitor obtained the lower than 0.6 V driving voltage drop with only 45% capacitance and around half of the voltage drop compared to a conventional bootstrap circuit. Besides, the proposed driver successfully tackled the parasitic ringing and dead-time overcharging issues in the GaN converter.