US Patent 7433412 Digital subscriber line induction neutralizing transformer network

A digital subscriber line (DSL) circuit is disclosed and includes at least one transformer exciting network (TEN) adapted to supply a low-impedance path to ground in response to an excitation current. The excitation current has a non-DSL frequency, and the low-impedance path to ground allows the excitation current to flow through a DSL induction neutralizing transformer (INT). The DSL INT is electrically coupled to the at least one TEN. The DSL INT is adapted to add longitudinal inductance to a telecommunication line in response to the excitation current, wherein the longitudinal inductance suppresses induced harmonic currents.