Calculation formula of lc filter in band-pass filter circuit
1. The filter is composed of a low-pass filter circuit composed of inductance and capacitance, which allows the current of useful signals to pass through, and has greater attenuation on interference signals with higher frequency.
2. Since there are two kinds of interference signals: differential mode and common mode, the filter should attenuate both kinds of interference.
3. There are three basic principles: (1) using the characteristics of capacitor passing through high frequency and isolating low frequency, the high-frequency interference current of live wire and neutral wire is introduced into the ground wire (common mode), or the high-frequency interference current of live wire is introduced into the neutral wire (differential mode); (2) The high frequency interference current is reflected back to the interference source by using the impedance characteristics of the inductance coil; (3) The interference suppression ferrite can absorb interference signals of a certain frequency band and convert them into heat. For the frequency band of a certain interference signal, select the appropriate interference suppression ferrite magnetic ring and magnetic bead to directly cover the cable to be filtered.