- 學位論文
交換式直流電壓轉換器的寬頻EMI干擾
Broadband EMI Noise in Switching DC-DC Regulator
摘要
降壓型電壓轉換器(Buck regulator)工作的時候，有一部分的能量 會成為電磁波輻射出去，造成系統上的電磁干擾。Buck 所生成的寬頻 電磁干擾，主要是來自high-side MOSFET 和low-side MOSFET 切換時 產生的雜訊，經由輸入電源傳遞出去。 要解決由Buck 輸入電源帶出的雜訊，最簡單的方式就是使用濾波元 件，可以有很好的效果。由於現代的整合型IC 相當進步，在switching node 上並無明顯的振鈴(ringing)，故傳統上各種解決switching node ringing 的對策，在現代IC 上已經效用不大，但這並不意味電源輸入不 會受high-side MOSFET 切換及low-side MOSFET 切換的影響，電源雜 訊會與switching node 電壓上升及下降的斜率有關。在考慮預留對策 時，可直接選用濾波型的對策作預留，以節省元件空間並得到最大效果。 由我們實驗的結果，可以發現電源線會帶出很大的電磁幅射雜訊， 而我們在Buck 的輸入電壓端加上濾波元件後，系統電磁干擾有顯著的 降低。
並列摘要
When buck regulator works, there is some energy leaks as EMI. The broadband EMI noise mainly is caused by high-side MOSFET toggling and low-side MOSFET toggling. Noise is carried via input power line. The simplest way to solve power line noise which is generated by buck circuit is an input filter. Due to highly integration in modem IC, the ringing of switching node is almost gone. Traditional solutions to improve switching node ringing becomes less effective now. However, it doesn’t' mean that input power won't be effected by high-side MOSFET toggling and low-side MOSFET toggling. Actually, input power noise is related to switching node voltage rising and falling time. If you have limited space for Buck EMI solution, please consider input filter as an optimization of effectivity and space. Per our experiment, we find out that the power line can carry noise and radiate large EMI. After we placing filter on buck’s input, the system’s EMI reduces significantly.