Browsing by Author "Kuo, Sy-Yen"

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Adaptive frequency control technique for enhancing transient performance of DC-DC converters
(2007)
Huang, Hong-Wei
;
Hsieh, Chun-Yu
;
Chen, Ke-Horng
;
Kuo, Sy-Yen
;
電控工程研究所
An adaptive frequency control (AFC) technique is proposed for minimizing transient dropout voltage and response time of switching DC-DC converters. As we know, nonlinear fast-transient techniques with fixed switching frequency can effectively regulate the unstable output voltage back to steady-state within a short time. However, they suffer from oscillation problem because of large sourcing or sinking recovery current at output of error amplifier by fast transient circuit. Therefore, linear operation provided by AFC technique can dynamically and smoothly adjust the switching frequency, which is proportional to the output voltage variation, to regulate output voltage back to its steady-state value. In other words, AFC technique eliminates system and sub-harmonic oscillation scenarios. Experimental results demonstrate the transient dropout voltage is improved 37.8% when load current changes from 100 mA to 500 mA.
Adaptive low-error fixed-width booth multipliers
(2007-06-01)
Song, Min-An
;
Van, Lan-Da
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Kuo, Sy-Yen
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資訊工程學系
;
Department of Computer Science
In this paper, we propose two 2's-complement fixed-width Booth multipliers that can generate an n-bit product from an n-bit multiplicand and an n-bit multiplier. Compared with previous designs, our multipliers have smaller truncation error, less area, and smaller time delay in the critical paths. A four-step approach is adopted to search for the best error-compensation bias in designing a multiplier suitable for VLSI implementation. Last but not least, we show the superior capability of our designs by inscribing it in a speech signal processor. Simulation results indicate that this novel design surpasses the previous fixed-width Booth multiplier in the precision of the product. An average error reduction of 65-84% compared with a direct-truncation fixed-width multiplier is achieved by adding only a few logic gates.
Dithering skip modulation, width and dead time controllers in highly efficient DC-DC converters for system-on-chip applications
(2007-11-01)
Huang, Hong-Wei
;
Chen, Ke-Horng
;
Kuo, Sy-Yen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes temperature-independent load sensor (LS), optimum width controller (OWC), optimum dead-time controller (ODC), and tri-mode operation to achieve high efficiency over an ultra-wide-load range. Higher power efficiency and wider loading current range require rethinking the control method for DC-DC converters.. Therefore, a highly efficient tri-mode DC-DC converter is invented in this paper for system-on-chip (SoC) applications, which is switched to sleeping mode at very light load condition or to high-speed mode at heavy load condition. The efficiency improvement is upgraded by inserting new proposed dithering skip modulation (DSM) between conventional pulse-width modulation (PWM) and pulse-frequency modulation (PFM). In other words, an efficiency-improving DSM operation raises the efficiency drop because of transition from PWM to PFM. Importantly, DSM mode can dynamically skip the number of gate driving pulses, which is inverse proportional to load current. Simplistically and qualitatively stated, the novel load sensor automatically selects optimum modulation method and power MOSFET width to achieve high efficiency over a wide load range. Moreover, optimum power MOSFET turn-on and turn-off delays in synchronous rectifiers and reduced ground bounce can save much switching loss by current-mode dead-time controller. Experimental results show the tri-mode operation can have high efficiency about 90% over a wide load current range from 3 to 500 mA. Owing to the effective mitigation of the switching loss contributed by optimum power MOSFET width and reduction of conduction loss contributed by optimum dead-times, the novel width and dead-time controllers achieve high efficiency about 95% at heavy load condition and maintain the highly efficient performance to very light load current about 0.1 mA.
Dithering skip modulator with a width controller for ultra-wride-load high-efficiency DC-DC converters
(2006-01-01)
Huang, Hong-Wei
;
Ho, Hsin-Hsin
;
Chien, Chieh-Ching
;
Chen, Ke-Horng
;
Ma, Gin-Kou
This paper proposes a temperature-independent load sensor to decide the optimum power MOSFET width for power saving of DC-DC converters. Besides, it also can decide the optimum modulation technique in tri-mode operation, which is composed of pulse-width modulation (PWM), pulse-frequency modulation (PFM), and a new proposed dithering sldp modulation (DSM). An efficiency-improving DSM operation is introduced to raise the efficiency drop because of transition from PWM to PFM. Importantly, DSM mode can dynamically sldp the number of gate driving pulses, which is inverse proportional to load current. Simplistically and qualitatively stated, the novel load sensor can automatically select the optimum modulation method and optimum power MOSFET width to achieve high efficiency over a wide load range. Experimental results show the tri-mode operation can have high efficiency about 89 % over a wide load current range from 3mA to 500mA. Owing to the effective mitigation of the switching loss contributed by large power MOSFET, the novel width controller not only achieves high efficiency about 95 % but also extends this high efficiency to a lower load current range about 0.1mA.
Fast transient DC-DC converter with on-chip compensated error amplifier
(2006)
Huang, Hong-Wei
;
Ho, Hsin-Hsin
;
Chien, Chieh-Ching
;
Chen, Ke-Horng
;
Ma, Gin-Kou
A novel fast transient DC-DC converter with on-chip compensated error amplifier is presented in this paper. The error amplifier uses on-chip current-mode Miller capacitor to replace a large off-chip capacitor. Only three transistors and one voltage follower are used to implement this novel architecture. Not only on-chip compensated error amplifier is implemented without off-chip components and I/O pins, but also it can have fast transient response. Furthermore, we accurately decrease the transient response time without suffering from the oscillation issue. Experimental results demonstrate the stability and the fast transient response of the DC-DC converters.
Fast-transient dc-dc converter with on-chip compensated error amplifier
(2007-12-01)
Chen, Ke-Horng
;
Huang, Hong-Wei
;
Kuo, Sy-Yen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A fast-transient dc-dc converter with on-chip compensated error amplifier is presented in this paper. The error amplifier uses three transistors and one voltage follower to implement the on-chip current-mode Miller capacitor. Not only on-chip compensated error amplifier is implemented without off-chip components and I/O pins, but also fast-transient response Is achieved. Moreover, we accurately decrease the transient response time without suffering from the oscillation issue. Implemented in a 0.35-mu m CMOS process, experimental results demonstrate the stability of converters with a little area overhead about 5% larger than that of conventional design. In case of load variations, there is about four times reduction on the dropout voltage compared to that of conventional design. Furthermore, transient speed by our proposed technique is about five times faster than that of conventional control, while the total quiescent current is only increased about 3%.
Highly efficient tri-mode control of buck converters with load sensing technique
(2006)
Huang, Hong-Wei
;
Chien, Chieh-Ching
;
Chen, Ke-Horng
;
Kuo, Sy-Yen
;
電控工程研究所
A highly efficient tri-mode buck converter with a novel load sensor circuit is proposed in this paper. The combination of pulse-width modulation (PWM), pulse-frequency modulation (PFM) and pulse-skipping circuit makes it efficient to operate in wide loading region. By using the novel load sensor, the buck converter can achieve high efficiency for the load range from 3mA to 400mA. This load sensor can automatically switch the modes according to the different load conditions. It changes the modulation methods from PWM mode to pulse-skipping modulation mode or to PFM mode. This tri-mode buck converter is fabricated by TSMC 0.35um. The efficiency above 90% is achieved for the load range about 90-400mA in PWM operation, and above 78 % attained for the load range about 3-50m.A in PFM mode. The insertion of the pulse skipping mode operation extends the high efficiency 90% of PWM operation for the load range from 90mA down to 50mA.
On-chip compensated error amplifier for fast transient DC-DC converters
(2006)
Huang, Hong-Wei
;
Ho, Hsin-Hsin
;
Chang, Chia-Jung
;
Chen, Ke-Horng
;
Kuo, Sy-Yen
A novel on-chip compensated error amplifier for fast transient response of DC-DC converters is presented in this paper. The error amplifier uses on-chip current-mode Miller capacitor to replace a large off-chip capacitor. We only use three transistors and one voltage follower to implement this novel on-chip compensated error amplifier for fast transient DC-DC converters. Owing to the current-mode implementation, we can redirect the equivalent current to charge or discharge the output capacitor of the error amplifier to improve the transient response time. Not only on-chip compensated error amplifier is implemented without off-chip components and I/O pins, but also it can have fast transient response. The analytic equations guarantee the compensated correctness of the proposed circuit. With the proposed error amplifier, the transient response of DC-DC converters is improved significantly. Simulation results demonstrate the stability and the fast transient response of the DC-DC converters.