A transformer includes: a magnetic core including a lower magnetic structure and an upper magnetic structure; a printed circuit board arranged between the lower magnetic structure and the upper magnetic structure and including a core hole through which a midsection of the magnetic core penetrates, a primary coil, a secondary coil, a primary via-hole formed at an end of the printed circuit board and electrically connected to the primary coil, and a secondary via-hole formed at another end of the printed circuit board and electrically connected to the secondary coil; a primary pin inserted into the primary via-hole; a secondary pin inserted into the secondary via-hole; an insulating block into which a portion of the printed circuit board is inserted; and a mount on which the printed circuit board and the insulating block are mounted.

A transformer includes: a magnetic core including a lower magnetic structure and an upper magnetic structure; a printed circuit board arranged between the lower magnetic structure and the upper magnetic structure and including a core hole through which a midsection of the magnetic core penetrates, a primary coil, a secondary coil, a primary via-hole formed at an end of the printed circuit board and electrically connected to the primary coil, and a secondary via-hole formed at another end of the printed circuit board and electrically connected to the secondary coil; a primary pin inserted into the primary via-hole; a secondary pin inserted into the secondary via-hole; an insulating block into which a portion of the printed circuit board is inserted; and a mount on which the printed circuit board and the insulating block are mounted.

A method of fabricating an inductor device includes preparing a conductive coil, connecting two terminals to one of two ends of the conductive coil, molding a pillar from a plurality of first composite material powders by a pressing process where each first composite material powder is composed of a first magnetic material powder coated with a first thermosetting resin, placing the pillar in a surrounding space formed by the conductive coil, molding a cladding body from a plurality of second composite powders where the second composite material powders is composed of a second magnetic material powder coated with a second thermosetting resin, heating the cladding body, the conductive coil and the pillar cladded by the cladding body such that the plurality of first magnetic material powders are bonded by the cured first thermosetting resin and the plurality of second magnetic material powders are bonded by the cured second thermosetting resin.

A method of fabricating an inductor device includes preparing a conductive coil, connecting two terminals to one of two ends of the conductive coil, molding a pillar from a plurality of first composite material powders by a pressing process where each first composite material powder is composed of a first magnetic material powder coated with a first thermosetting resin, placing the pillar in a surrounding space formed by the conductive coil, molding a cladding body from a plurality of second composite powders where the second composite material powders is composed of a second magnetic material powder coated with a second thermosetting resin, heating the cladding body, the conductive coil and the pillar cladded by the cladding body such that the plurality of first magnetic material powders are bonded by the cured first thermosetting resin and the plurality of second magnetic material powders are bonded by the cured second thermosetting resin.

A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

An inductor component includes an element body including magnetic powder and having first and second principal surfaces; an inductor wiring in the element body; a first vertical wiring that is in the element body, is connected to a first end portion of the inductor wiring, and extends to the first principal surface; a second vertical wiring that is in the element body, is connected to a second end portion of the inductor wiring, and extends to the first principal surface; and first and second external terminals exposed on the first principal surface and connected to the first and second vertical wirings, respectively. The magnetic powder contains an Fe element as a main component, and the first principal surface has an oxidized region, in which an oxide film of oxidized particles of the magnetic powder, is exposed and a non-oxidized region in which particles of the magnetic powder are exposed.

An inductor component includes an element body including magnetic powder and having first and second principal surfaces; an inductor wiring in the element body; a first vertical wiring that is in the element body, is connected to a first end portion of the inductor wiring, and extends to the first principal surface; a second vertical wiring that is in the element body, is connected to a second end portion of the inductor wiring, and extends to the first principal surface; and first and second external terminals exposed on the first principal surface and connected to the first and second vertical wirings, respectively. The magnetic powder contains an Fe element as a main component, and the first principal surface has an oxidized region, in which an oxide film of oxidized particles of the magnetic powder, is exposed and a non-oxidized region in which particles of the magnetic powder are exposed.

A magnetic powder contains a magnetic metal particle comprising iron (Fe) and an insulating coating layer disposed on a surface of the magnetic metal particle and comprising tin (Sn), phosphorous (P) and oxygen (O), and a coil component contains such a magnetic powder.

An inductor component includes a multilayer body including a magnetic layer; an inductor wiring disposed inside the multilayer body; and an external terminal exposed from the multilayer body. The multilayer body or the external terminal has an overlapping region disposed on the inductor wiring and a non-overlapping region not in contact with the inductor wiring, and reflection spectra of the overlapping region is different from reflection spectra of the non-overlapping region when irradiated with light having a prescribed wavelength from an outer surface side.