Patent ID: 7453326

Claim:
A nonreciprocal circuit device comprising: permanent magnets; a ferrite having a substantially rectangular shape to which a direct magnetic field is applied using the permanent magnets; a first central electrode made of conductive films arranged on first and second main surfaces including longer sides of the ferrite and substantially extending along diagonal lines of the first and second main surfaces so as to be arranged substantially parallel to each other, the first central electrode having one end electrically connected to an input port and the other end electrically connected to an output port; a second central electrode made of conductive films arranged so as to intersect the first central electrode in an insulated manner, the second central electrode being wound around the first and second main surfaces of the ferrite in a short-side direction and having one end electrically connected to the output port and the other end electrically connected to a ground port; a first matching capacitor electrically connected between the input port and the output port; a second matching capacitor electrically connected between the output port and the ground port; a third matching capacitor electrically connected between the input port and the ground port; a resistor electrically connected between the input port and the output port; and a circuit substrate having terminal electrodes provided on a surface thereof; wherein the ferrite and the permanent magnets are included in a ferrite-magnet assembly and arranged such that the pair of permanent magnets sandwiches the ferrite from the first and second main surfaces of the ferrite; the ferrite-magnet assembly is arranged on the circuit substrate so that the first and second main surfaces are arranged in a substantially vertical direction relative to the surface of the circuit substrate; and one of the conductive films of the first central electrode is arranged through an insulating film on a plurality of the conductive films of the second central electrode which are arranged on one of the first and second main surfaces of the ferrite.