Patent ID: 9577302
Date: 2017-02-21
CPC Classifications: H01P,H03H

Claim:
1. An RF filter circuit, comprising: an input port with an input terminal; an output port with an output terminal; a signal path between the input port and the output port, the signal path having a first series resonator; a ground terminal; a first coupling conductor segment that is a part of the signal path, the first coupling conductor segment being directly connected to the input terminal; and a second coupling conductor segment directly connected to the output terminal or to the ground terminal, wherein the first coupling conductor segment and the second coupling conductor segment are arranged next to each other and are electromagnetically coupled such that the coupling enhances attenuation of the RF filter circuit in a rejection frequency band, wherein the first coupling conductor segment and the second coupling conductor segment are aligned in parallel, wherein the first coupling conductor segment and the second coupling conductor segment are dedicated to conduct RF signals in opposite directions, wherein the first coupling conductor segment and the second coupling conductor segment establish a segment of a coupled differential signal line, and wherein the first coupling conductor segment and the second coupling conductor segment are dedicated to carry currents that have opposite directions and are out of phase.