Are you all familiar with methods such as using filtering capacitors, common-mode inductors, and ferrite beads to eliminate electromagnetic interference 1

Electromagnetic interference is common in circuits. Do you know how to eliminate it? Eliminating electromagnetic interference is a quite challenging issue. In fact, you can use three main types—filter capacitors, common-mode inductors, and ferrite beads—to suppress it. Do you all know about their roles in circuits? Many engineers still struggle to understand these three. This article provides a detailed analysis of the principles behind these three key tools for EMC suppression in design. diode

Although the resonance of the BQ27520YZFR-G3 capacitor is undesirable from the perspective of filtering high-frequency noise, it is not always harmful. When the frequency of the noise to be filtered is determined, the capacitance can be adjusted to ensure the resonance point precisely falls on the disturbance frequency. In practical engineering, the frequencies of electromagnetic noise to be filtered often reach hundreds of MHz or even exceed 1 GHz. For such high-frequency electromagnetic noise, core-through capacitors must be used to achieve effective filtering.

The reason why ordinary capacitors cannot effectively filter out high-frequency noise is due to two factors:

One reason is that the inductance of capacitor leads causes capacitor resonance, presenting a high impedance to high-frequency signals and weakening their bypass effect;

Another reason is that the parasitic capacitance between the conductors causes coupling of high-frequency signals, reducing the filtering effect.  diode

Through-hole capacitors can effectively filter high-frequency noise because they not only avoid the issue of excessively low resonant frequency caused by lead inductance but also allow direct installation on metal panels, leveraging the metal panels for high-frequency isolation. However, when using through-hole capacitors, attention must be paid to the installation process.