High-efficiency, tri-mode, low-EMI synchronized buck DC-DC converter

doi:10.3969/j.issn.1000-5641.2026.02.008

Abstract

Abstract:

This paper presents a tri-mode buck converter designed using the 55 nm Complementary Metal-Oxide-Semiconductor (CMOS) process, which offers a peak efficiency of 92.95% for low-EMI applications. The converter employs a seamless transition between pulse-width modulation (PWM), pulse-frequency modulation (PFM), and pulse-skip modulation (PSM) modes under various load conditions, which optimizes the efficiency and ripple performance from light to heavy loads. By implementing spread-spectrum frequency modulation with 35% frequency dithering, the converter reduces the peak of the output voltage spectrum by 22 dB, thus significantly reducing the EMI emission spectrum.

Key words: buck converter, low-EMI, spread spectrum frequency modulation (SSFM), multiple operating modes, high efficiency

CLC Number:

TN432

Shixiang DING, Songmao HAO, Chunqi SHI. High-efficiency, tri-mode, low-EMI synchronized buck DC-DC converter[J]. J* E* C* N* U* N* S*, 2026, 2026(2): 82-94.

Figures/Tables 14

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Table 1

References 19

1	联合资信评估股份有限公司. 消费电子行业2024年运行情况回顾及2025 年展望 [R/OL]. (2024-12-30)[2025-08-29]. https://www.lhratings.com/file/fc8196382fe.pdf.
2	HEGARTY T. An overview of conducted EMI specifications for power supplies [R/OL]. (2018-02)[2025-08-29]. https://www.ti.com/lit/pdf/slyy136.
3	ZHANG B Y, WANG S.. A survey of EMI research in power electronics systems with wide-bandgap semiconductor devices. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020, 8 (1): 626- 643.
4	LEONCINI M, BERTOLINI A, MELILLO P, et al.. Spread-spectrum frequency modulation in a DC/DC converter with time-based control. IEEE Transactions on Power Electronics, 2023, 38 (4): 4207- 4211.
5	Texas Instruments. CISPR 25 class5 400-kHz 12-W automotive USB Type-A charger reference design [R/OL]. (2020-09) [2025-08-29]. https://www.ti.com/lit/ug/tidt197/tidt197.pdf.
6	CHU Y, RAMADASS Y. Active EMI filters to reduce size and cost of EMI filters in automotive systems [J/OL]. Analog Design Journal, [2025-08-29]. https://www.ti.com/lit/an/slyt812/slyt812.pdf.
7	PARESCHI F, ROVATTI R, SETTI G.. EMI reduction via spread spectrum in DC/DC converters: State of the art, optimization, and tradeoffs. IEEE Access, 2015, 3, 2857- 2874.
8	LIN F, CHEN D Y.. Reduction of power supply EMI emission by switching frequency modulation. IEEE Transactions on Power Electronics, 1994, 9 (1): 132- 137.
9	PAKALA S H, SURKANTI P R, FURTH P M.. A spread-spectrum mode enabled ripple-based buck converter using a clockless frequency control. IEEE Transactions on Circuits and Systems Ⅱ: Express Briefs, 2019, 66 (3): 382- 386.
10	CHEN K. EMI 的工程师指南第9部分—扩频调制 [R/OL]. (2019-08-06) [2025-08-29]. https://e2echina.ti.com/blogs_/b/power_house/posts/emi-9.
11	郭海燕, 张波, 李肇基.. 扩频DC/DC变换器的纹波分析. 电力电子技术, 2009, 43 (6): 24- 25.
12	SCOTT K, ZIMMER G. 扩频频率调制以降低EMI [R/OL]. (2015-11-4) [2025-08-29]. https://www.analog.com/cn/resources/technical-articles/spread-spectrum-frequency-modulation-reduces-emi.html.
13	KAO Y H, HUNG C S, CHANG H H, et al. 8.11 a 48V-to-5V buck converter with triple EMI suppression circuit meeting CISPR 25 automotive standards [C]// 2024 IEEE International Solid-State Circuits Conference (ISSCC). IEEE, 2024: 164-166.
14	WICHT B. Design of Power Management Integrated Circuits [M]. Hannover: Wiley, 2024.
15	JIANG H W, WANG P P, MERCIER P P, et al.. A 0.4-V 0.93-nW/kHz relaxation oscillator exploiting comparator temperature-dependent delay to achieve 94-ppm/℃ stability. IEEE Journal of Solid-State Circuits, 2018, 53 (10): 3004- 3011.
16	SANSEN B W M C. Analog Design Essentials [M]. Netherlands: Springer, 2006: 478-479.
17	杨建国. 新概念模拟电路 [M/OL]. [2025-08-29]. https://www.analog.com/cn/lp/002/intelligence/analog-circuit-compilation-yang.html.
18	YANG W H, CHIU S W, KUO C C, et al. A true-random-number-based pseudohysteresis controller for buck DC-DC converter in high-security Internet-of-everything devices [J]. IEEE Transactions on Power Electronics, 2020, 35(3): 2969-2978.
19	HU J W, ZHOU Y. A buck converter for 5G NR RF-PA with 400 ns rise- and fall-time and spread spectrum switching [C]// 2021 IEEE International Symposium on Circuits and Systems (ISCAS). IEEE, 2021: 1-4.

参数	Leoncini等^[4]	Yang等^[18]	Hu等^[19]	本文
工艺	180 nm CMOS	55 nm CMOS	180 nm CMOS	55 nm CMOS
输入电压	2.8~4.2 V	4.5~5.5 V	2.5~5.5 V	2.7~3.3 V
输出电压	1.3~2.2 V	1.8~3.3 V	0.5~4.8 V	1.8 V
工作模式	CFC PWM	PWM	PWM	PSM/PFM/PWM
扩频调制方法	固定斜率调制	真随机数伪滞后调制	固定斜率调制	固定斜率调制
扩频中心频率	9.5 MHz	1 MHz	12.2 MHz	1.2 MHz (CCM模式) 0.1 MHz (DCM模式)
最大扩频百分比	30%	43%	25%	35%
频谱峰值降低量	19 dB*	35.4 dB	20 dB*	22 dB*
支持DCM工作模式	否	否	否	是
峰值效率	88.2%	92.4%	90.5%	92.95%
轻载效率 (10 mA)	<60%	<70%	<60%	86%

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