A filter circuit includes: a wiring pattern provided in an upper wiring layer of a printed circuit board, a wiring pattern provided in a lower wiring layer of the printed circuit board, a wiring pattern extending from one end of the wiring pattern, a wiring pattern provided so as to partially face the wiring pattern in the upper wiring layer, a bypass capacitor provided in the upper wiring layer and connected to the wiring pattern and a ground conductor surface, a via connecting one end of the wiring pattern and the wiring pattern, and a via connecting the wiring pattern and the wiring pattern. A structure including the wiring pattern, the via, and the wiring pattern faces a structure including the via and the wiring pattern.

A filter module includes an inductor, a filter including first wiring, and second wiring between the inductor and the first wiring and being a direct-current floating potential. The inductor and the first wiring are magnetically coupled, the inductor and the second wiring are magnetically coupled, and the first wiring and the second wiring are capacitively coupled.

A filter module includes an inductor, a filter including first wiring, and second wiring between the inductor and the first wiring and being a direct-current floating potential. The inductor and the first wiring are magnetically coupled, the inductor and the second wiring are magnetically coupled, and the first wiring and the second wiring are capacitively coupled.

A diplexer includes a first filter circuit including a first loop inductor defining a first loop plane and a second loop inductor defining a second loop plane, a second filter circuit adjacent to the first filter circuit, and a first via hole conductor that electrically connects an input/output terminal, the first filter circuit and the second filter circuit to each other. The first loop plane faces the second loop plane while protruding beyond the second loop plane in a first direction. The first via hole conductor is provided relative to the first loop inductor in a second direction from the first loop plane toward the second loop plane, and is superposed with a portion of the first loop plane that protrudes beyond the second loop plane when viewed in the second direction.

A band pass filter includes parallel resonators. An inductor of a first parallel resonator at an intermediate stage is divided into a first inductor and a second inductor connected in parallel with each other. The first inductor and an inductor of a second parallel resonator are in magnetic coupling with each other, and the second inductor and an inductor of a third parallel resonator are in magnetic coupling with each other.

A band pass filter includes parallel resonators. An inductor of a first parallel resonator at an intermediate stage is divided into a first inductor and a second inductor connected in parallel with each other. The first inductor and an inductor of a second parallel resonator are in magnetic coupling with each other, and the second inductor and an inductor of a third parallel resonator are in magnetic coupling with each other.

An electronic component includes a second inductor including a second inductor conductor that includes a first coupling portion electrically coupled to a second capacitor conductor and a second coupling portion electrically coupled to a second ground conductor, and when viewed in a plan view from a lamination direction, a first region surrounded by a first inductor conductor and the second inductor conductor is smaller in area than a second region surrounded by a third inductor conductor layer and the second inductor conductor, and a second region forming portion, which is included in the second inductor conductor and surrounds the second region, and a first region forming portion, which is included in the second inductor conductor and surrounds the first region, are electrically coupled in series in this order on a path from the first coupling portion to the second coupling portion.

An electronic component includes a second inductor including a second inductor conductor that includes a first coupling portion electrically coupled to a second capacitor conductor and a second coupling portion electrically coupled to a second ground conductor, and when viewed in a plan view from a lamination direction, a first region surrounded by a first inductor conductor and the second inductor conductor is smaller in area than a second region surrounded by a third inductor conductor layer and the second inductor conductor, and a second region forming portion, which is included in the second inductor conductor and surrounds the second region, and a first region forming portion, which is included in the second inductor conductor and surrounds the first region, are electrically coupled in series in this order on a path from the first coupling portion to the second coupling portion.

Coupling apparatuses, circuits having such coupling apparatuses and corresponding methods are provided that involve a first and a second signal being coupled out from an out-coupling circuit part and being separately coupled into first and second circuit pmts. The use of different coupling mechanisms effects signal separation in this case. In particular, one of the signals can be coupled as a differential signal and the other as a common mode signal.

A differential signal represented by a voltage difference between two signals that propagate through two signal lines is input to a signal processing circuit from a connector. A first suppressing circuit and a second suppressing circuit suppress peak values of the two signals. A DC removing circuit removes DC components of the two signals. A common mode choke coil (noise removing circuit) removes common mode noise included in the two signals. The DC removing circuit and the noise removing circuit are disposed between the first suppressing circuit and the second suppressing circuits. If the voltage of the signal line is a first threshold voltage, a current flows through a first suppressing device (first connection device). If the voltage of the signal line is a second threshold voltage, a current flows through a second suppressing device (second connection device). The second threshold voltage is less than the first threshold voltage.