An apparatus is provided. The apparatus includes an electronic circuit for processing a differential signal. A device including an electronic circuit may include a first inductor and a second inductor that process a differential signal, a first circuit connected to the first inductor in parallel, a second circuit connected to the second inductor in parallel, and lines connecting the first inductor and the first circuit, the lines being disposed to pass through an area defined by the first inductor and the second inductor. The first inductor and the second inductor have symmetrical differential structures.

In a multilayer filter, a first LC parallel resonance unit, a second LC parallel resonance unit, and an LC circuit unit are configured in an element body, in which the LC circuit unit is connected between the first LC parallel resonance unit and the second LC parallel resonance unit in a path between a first terminal electrode and a second terminal electrode, a conductor pattern constituting an inductor of the LC circuit unit is not disposed between a conductor pattern constituting a first inductor of the first LC parallel resonance unit and a conductor pattern constituting a second inductor of the second LC parallel resonance unit in the element body, and the first inductor of the first LC parallel resonance unit and the second inductor of the second LC parallel resonance unit are magnetically coupled.

A filter (10) includes two capacitors (C1a and C1b) that are connected in series on a path connecting an input terminal (101a) and an output terminal (102a), an inductor (L2) that is connected in parallel with a series circuit including the two capacitors (C1a and C1b), and a parallel-arm resonator (P1) that is connected between the ground and a node (N) between the two capacitors (C1a and C1b) on the path.

A low pass filter includes a first inductor, a second inductor magnetic-field-coupled to the first inductor, a third inductor, and a first capacitor. The first inductor is electrically connected between a first port and an intermediate node, being a node to which the second inductor is electrically connected, between the first inductor and the second port. The second inductor is electrically connected between the intermediate node and a ground terminal. The third inductor is electrically connected between the intermediate node and the second port, and a first parallel resonant circuit is defined by the third inductor and the first capacitor. The first inductor and the second inductor are coupled to each other in such a relationship that a negative inductance is generated between the intermediate node and the third inductor due to magnetic field coupling between the first inductor and the second inductor.

A planar radio frequency filter is described, comprising a frequency selective surface (FSS) applied to a substrate. The filter blocks the transmission of electromagnetic waves in at least two independent radio frequency bands. The FSS comprises a periodic array of multipole inclusions with skewed or forked poles to increase packing density. The inclusions comprise four or six primary poles to generate the lower frequency resonance and an additional four or six secondary poles to generate the higher frequency resonance. The secondary inclusions are located between the primary inclusions to tune the higher resonance frequency. The FSS incorporates overlapping parallel conducting segments that overlap to provide an inductive-capacitive path between adjacent inclusions.

A multilayer circuit board with an LC resonant circuit that has an electronic component package including the multilayer circuit board with the LC resonant circuit are provided. The multilayer circuit board with the LC resonant circuit configured by alternately laminating conductive layers and insulating resin layers on both sides of a core substrate includes a first set of wiring lines, a set of vias, and a second set of wiring lines. The first set of wiring lines configures both ends of the LC resonant circuit and is formed in a first one of the conductive layers. The set of vias extends through the insulating resin layers. The second set of wiring lines is connected to an input/output terminal of the LC resonant circuit and is formed in a second one of the conductive layers. The first set of wiring lines is connected to the second set of wiring lines.

A planar radio frequency filter is described, comprising a frequency selective surface (FSS) applied to a substrate. The filter blocks the transmission of electromagnetic waves in at least two independent radio frequency bands. The FSS comprises a periodic array of multipole inclusions with skewed or forked poles to increase packing density. The inclusions comprise four or six primary poles to generate the lower frequency resonance and an additional four or six secondary poles to generate the higher frequency resonance. The secondary inclusions are located between the primary inclusions to tune the higher resonance frequency. The FSS incorporates overlapping parallel conducting segments that overlap to provide an inductive-capacitive path between adjacent inclusions.

In a band pass filter, a signal input into a first terminal is transmitted to a first LC resonator and a second LC resonator in this order and is then output from a second terminal. The band pass filter includes a third inductor and a third capacitor. A first end of the third inductor is electrically connected to the ground. The third capacitor is electrically connected between a second end of the third inductor and a node between the first LC resonator and the second LC resonator.

A resonant element includes first, second, and third plane electrodes, a first via electrode defining a first inductor, a second inductor, and a third inductor. The first via electrode connects the first plane electrode and the second plane electrode, and each of the second inductor and the third inductor connects the first plane electrode and the third plane electrode. The third plane electrode defines a first capacitor together with the second plane electrode, the second inductor includes second via electrodes, and the third inductor includes third via electrodes. Each of the second via electrodes and the third via electrodes is a columnar conductor extending in the extending direction of the first via electrode.

In a multilayer filter, a first LC parallel resonance unit, a second LC parallel resonance unit, and an LC circuit unit are configured in an element body, in which the LC circuit unit is connected between the first LC parallel resonance unit and the second LC parallel resonance unit in a path between a first terminal electrode and a second terminal electrode, a conductor pattern constituting an inductor of the LC circuit unit is not disposed between a conductor pattern constituting a first inductor of the first LC parallel resonance unit and a conductor pattern constituting a second inductor of the second LC parallel resonance unit in the element body, and the first inductor of the first LC parallel resonance unit and the second inductor of the second LC parallel resonance unit are magnetically coupled.