Patent ID: 7679470

Claim:
A nonreciprocal circuit device comprising: a permanent magnet; a ferrite to which the permanent magnet applies a direct-current magnetic field; a first central electrode arranged on the ferrite and having one end thereof electrically connected to an input port and another end thereof electrically connected to an output port; a second central electrode arranged on the ferrite, crossing the first central electrode so as to be electrically insulated from the first central electrode, and having one end thereof electrically connected to the output port and the other end thereof electrically connected to a ground port; a first matching capacitor electrically connected between the input port and the output port; a resistor electrically connected between the input port and the output port; a second matching capacitor electrically connected between the output port and the ground port; and a circuit board having a terminal electrode on the surface thereof; wherein the ferrite has a substantially rectangular parallelepiped shape; the first central electrode includes electrode layers provided on a pair of main surfaces of the ferrite and connected to each other by an electrode arranged on a side surface of the ferrite continuous to the main surfaces of the ferrite; and the second central electrode includes electrode layers provided on the pair of main surfaces of the ferrite and connected to each other by an electrode arranged on the side surface of the ferrite that is continuous with the main surfaces of the ferrite, the second electrode wound at least about three turns around the ferrite, a width dimension of the electrode layer wound as the outermost winding of the second central electrode being greater than a width dimension of the electrode layer wound as an inner winding of the second central electrode.