Impedance matching circuit and noise filter equipped with the same

Abstract

A bridge tap branches from a two-wire transmission line for communications and is connected to a terminal-function assisted noise filter which is then connected at the downstream end with a telephone. The terminal-function assisted noise filter comprises a terminal circuit (an impedance matching circuit with four ports) and a noise removing circuit. The terminal circuit consists mainly of two resistors connected in series with the bridge tap and a capacitor connected in parallel with the same. Accordingly, the impedance matching circuit and the noise filter equipped with the impedance matching circuit can be implemented where the communicating action of a data communication device over the main line is protected from being interfered by reflection waves derived from the bridge tap.

Dependencies are inferred from the claim text.