An electronic filter is an arrangement of electronic components used in a circuit to transmit signals within a given frequency range, rejecting others. Electronic filters are used in radios, television receivers, telephone systems, etc.

A low-pass filter transmits frequencies below a specified cut-off and blocks out higher frequencies; typically it consists of an inductor in series with a capacitor shunted across the load to short out high-frequency current. In a high-pass filter the inductor and capacitor are interchanged and only high frequencies are transmitted. A bandpass filter blocks all frequencies outside two limits.