电子元件与材料2025，Vol.44Issue(3)：301-308,8.DOI:10.14106/j.cnki.1001-2028.2025.1499
一种降低开关电源EMI的混合扩频电路
A hybrid spread spectrum circuit for reducing EMI of switch power supply
摘要
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.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Key words
periodic current/random current/hybrid spread spectrum/current ripple/EMI reduction分类
信息技术与安全科学引用本文复制引用
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):301-308,8.基金项目
国家自然科学基金(1237042061,6197032209) （1237042061,6197032209）
