一种降低开关电源EMI的混合扩频电路

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关键词：周期电流；随机电流；混合扩频；电流纹波；电磁干扰抑制

中图分类号：TN432

文献标识码：A

DOI：10.14106/j.cnki.1001-2028.2025.1499

引用格式：曹倡源， 栾苏珍. 一种降低开关电源EMI的混合扩频电路 [J]. 电子元件与材料， 2025， 44（3）： 301-308.

Reference format： CAO Changyuan， LUAN Suzhen. A hybrid spread spectrum circuit for reducing EMI of switch power supply [J]. Electronic Components and Materials， 2025， 44（3）： 301-308.

A hybrid spread spectrum circuit for reducing EMI of switch

power supply

CAO Changyuan， LUAN Suzhen

（School of Communication and Information Engineering， Xian University of Science and Technology， Xian

710054， China）

Abstract： To solve the problems of audible noise in traditional periodic spread spectrum modulation and significant frequency step changes in random spread spectrum modulation， a hybrid spread spectrum circuit for switching power supplies was designed. The periodic triangular wave modulation and random modulation frequency characteristics were combined in the circuit to generate a modulated signal. As a result， the frequency step change was reduced and the randomness was enhanced in the switching frequency. The audible noise can be avoided while strengthening the suppression of electromagnetic interference （EMI）. The hybrid spread spectrum circuit mainly consists of a periodic current module and a random current module， the mixed frequency changes of the modulation signal are achieved by superimposing these two current signals to charge and discharge a capacitor. Theoretical analysis and Simulink simulation demonstrate that EMI can be effectively suppressed by the mixed modulation signal. Finally， a Buck converter using a mixed spread spectrum circuit was built based on TSMC 0.18 μm technology for the test and verification. The results show that the ripple of the inductor current is reduced and the EMI energy spikes are dispersed to other frequency ranges in Buck. When the load current is stable at 500 mA， the maximum EMI amplitude is reduced by about 13.03 dB， which can provide a valuable reference for the design of low-EMI power chips.

Keywords：  periodic current; random current; hybrid spread spectrum; current ripple; EMI reduction

DC-DC变换器广泛用于新能源、仪器仪表、工业自动化、消费电子等领域 [1]，具有重要的学术价值及产业价值 [2]。（剩余8525字）