Electronic filters are devices that process and remove unwanted frequencies from a signal or power line. The most common type of filter is the passive filter, which uses a combination of resistor, inductors and capacitors to block or conduct high or low frequency signals.
A low-pass filter allows low frequencies to pass through the circuit and suppresses high frequencies, and high-pass filters allow high frequencies to pass. Band-pass filters allow frequencies within a certain range, and band-stop filters allow frequencies outside of a certain range. The type of filter used depends on application requirements.
Electronic filters are typically used to suppress electromagnetic and radio frequency interference, mitigate harmonics, and protect valuable equipment like motors and drive from undesired power conditions.