Active Filter Working Principle

Filter is composed of inductance and capacitance of the low-pass filtering circuit, which allows the current of the useful signal to pass through, the higher frequency interference signal has a greater attenuation. As the interference signal has a differential mode and **** mode two, so the filter should have attenuation of these two kinds of interference. There are three basic principles:

(1) the use of capacitors through the high-frequency isolation of low-frequency characteristics of the firewire, zero line high-frequency interference current into the ground (*** mode), or the firewire high-frequency interference current into the zero line (differential mode);

(2) the use of inductive coils of impedance characteristics of the high-frequency interference current is reflected back to the source of the interference;

(3) the use of interference suppression of the ferrite Can be a certain frequency band of interference signal absorption into the heat of the characteristics of the frequency band for a certain interference signal to select the appropriate interference suppression ferrite ring, beads directly set in the need to filter the cable can be.