A New Improved Second-Order Delta-Sigma-Modulation Buck Converter With Low-Noise and Transient-Acceleration Loops

In this article, we propose a new improved fast-transient-response and low-noise high-efficiency buck converter with second-order continuous-time delta-sigma-modulation (CT-DSM) techniques. First, by utilizing the oversampling theorem and noise-shaping technique with the second-order delta-sigma mod...

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Bibliographic Details
Published in:IEEE transactions on industrial electronics (1982) 2022-01, Vol.69 (1), p.64-73
Main Authors: Chen, Jiann-Jong, Hwang, Yuh-Shyan, Ku, Yitsen, Chen, Jian-An, Lai, Chien-Hung
Format: Article
Language:English
Subjects:
Buck converter
Buck converters
Electromagnetic interference
fast transient response
Frequency conversion
Frequency modulation
low electromagnetic interference (EMI)
low transient voltage
Modulation
Noise
Operational amplifiers
Oversampling
Recovery time
second-order delta-sigma modulation
Transconductance
Transient analysis
Transient response
Voltage control
Voltage dividers
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Summary:In this article, we propose a new improved fast-transient-response and low-noise high-efficiency buck converter with second-order continuous-time delta-sigma-modulation (CT-DSM) techniques. First, by utilizing the oversampling theorem and noise-shaping technique with the second-order delta-sigma modulation, the output noise within the bandwidth can be reduced effectively. Second, the adding of the transient acceleration loop not only can improve the transient recovery time when the load current changed but also lowers the undershoot and overshoot voltage. Third, a rail-to-rail operational transconductance amplifier without voltage dividers is employed in the proposed converter, which helps sensing the inductor current, moving the inductor pole to a high frequency, speeding up the transient response, and stabilizing the proposed converter modules. Finally, the proposed converter has been implemented with TSMC 0.18 μm 1P6M process and occupies an area of 1.19 × 1.19 mm 2 . When the load current changed from 50 to 500 mA and 500 to 50 mA, the transient recovery time was both 4 μs, which improved 8 and 16 μs than the traditional CT-DSM converter. The output voltage ripples are kept under 13 mV and the overshoot and undershoot voltage is 20 and 14 mV, respectively. The measured output-to-noise ratio is 80.7 dB, with the sampling frequency of 10 MHz. The peak efficiency is 92.1%, at the output voltage of 2.5 V and load current of 150 mA.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2020.3048318