Abstract: A front end circuit includes a circulator having a first port into which a transmission signal is input, a second port into/from which a transmission/reception signal is input/output, and a third port from which a reception signal is output. The impedance of the second port of the circulator is set to a value different from the impedance value of the first port and the third port. With his configuration, the narrowing of a frequency band and the increase in loss, which occur when an impedance matching circuit is additionally provided, are prevented.

Abstract: In a nonreciprocal circuit element (circulator), first, second, and third center conductors are disposed on a ferrite, to which a direct current magnetic field is applied, so as to be insulated from one another and so as to intersect with one another. One ends of the first, the second, and the third center conductors are defined as a first port, a second port, and a third port, respectively. The first port, the second port, and the third port are connected to a first terminal, a second terminal, and a third terminal, respectively. The other ends of the center conductors are connected to one another and are then connected to a ground. Capacitance elements are connected in parallel to the center conductors, respectively. Capacitors are provided in series or parallel to the first, the second, and the third center conductors, respectively.

Abstract: In a non-reciprocal circuit device, a first center conductor, a second center conductor, and a third center conductor are disposed on a ferrite, to which a direct current magnetic field is applied by a permanent magnet, so as to be insulated from one another and so as to intersect with one another. One end of the first center conductor defines a first port, one end of the second center conductor defines a second port, and one end of the third center conductor defines a third port. The first port is connected to a first terminal, the second port is connected to a second terminal, and the third port is connected to a third terminal. The other ends of the respective center conductors are connected to one another, which is connected to a ground. Capacitance elements are connected in parallel to the respective center conductors.

Abstract: A nonreversible circuit device includes circulators of high pass type, each circulator including a first central conductor, a second central conductor, and a third central conductor arranged on a microwave magnetic body, to which a DC magnetic field is applied, in a relation intersecting each other in a mutually insulated state, and capacitance elements connected respectively in series between one end of the first central conductor and an antenna port, between one end of the second central conductor and a reception port, and between one end of the third central conductor and a transmission port. A pass frequency band of the circulator is lower than that of the circulator. The antenna ports of the circulators are electrically connected to provide one combined antenna port, and a low pass filter is inserted between the combined antenna port and the antenna port of the circulator.

Abstract: A front end circuit and a wireless communication device capable of achieving matching with an antenna across a wide frequency band and capable of suppressing degradation in high-frequency characteristics caused by the influence of transmission signal harmonics is provided. A front end circuit includes a variable matching circuit connected to a low-frequency band transmission port side of a diplexer and a harmonic filter connected between the variable matching circuit and the diplexer. The harmonic filter has a pass band that overlaps with a low-frequency band-side communication band and a stop band that overlaps with a harmonic frequency of the low-frequency band-side communication band.

Abstract: A nonreversible circuit device includes circulators of high pass type, each circulator including a first central conductor, a second central conductor, and a third central conductor arranged on a microwave magnetic body, to which a DC magnetic field is applied, in a relation intersecting each other in a mutually insulated state, and capacitance elements connected respectively in series between one end of the first central conductor and an antenna port, between one end of the second central conductor and a reception port, and between one end of the third central conductor and a transmission port. A pass frequency band of the circulator is lower than that of the circulator. The antenna ports of the circulators are electrically connected to provide one combined antenna port, and a low pass filter is inserted between the combined antenna port and the antenna port of the circulator.

Abstract: An isolator includes a core isolator, a main substrate and a circuit-defining section. The main substrate includes a first wiring portion, a second wiring portion and a third wiring portion and has the core isolator and the circuit-defining section mounted thereon. An input port of the core isolator is connected to the first wiring portion. An output port of the core isolator is connected to the second wiring portion. A ground port of the core isolator is connected to the third wiring portion. In the circuit-defining section, a conductor pattern includes a capacitor that is connected in parallel with the core isolator via the first wiring portion and the second wiring portion, and an impedance element that is connected to at least either of the first wiring portion and the second wiring portion.

Abstract: In a non-reciprocal circuit device, a first center conductor, a second center conductor, and a third center conductor are disposed on a ferrite, to which a direct current magnetic field is applied by a permanent magnet, so as to be insulated from one another and so as to intersect with one another. One end of the first center conductor defines a first port, one end of the second center conductor defines a second port, and one end of the third center conductor defines a third port. The first port is connected to a first terminal, the second port is connected to a second terminal, and the third port is connected to a third terminal. The other ends of the respective center conductors are connected to one another, which is connected to a ground. Capacitance elements are connected in parallel to the respective center conductors.

Abstract: A non-reciprocal circuit element includes a ferrite, a first central electrode and a second central electrode arranged on the ferrite so as to cross each other in an insulated state, and a permanent magnet that applies a DC magnetic field to a portion where the first and second central electrodes cross each other. One end of the first central electrode defines an input port, and the other end thereof defines an output port. One end of the second central electrode defines the input port, and the other end thereof defines a ground port. A resistance element and a capacitance element, which are connected in parallel with each other, are connected in series with and between the input port and the output port. Input impedance is lowered by making inductance of the second central electrode relatively large.

Abstract: A nonreciprocal circuit device includes a permanent magnet, a ferrite to which the permanent magnet applies a direct-current magnetic field, first and second central electrodes arranged on the ferrite, and a circuit board. The first central electrode includes electrode layers provided on main surfaces of the ferrite connected by an electrode provided on a top surface of the ferrite. A second central electrode includes electrode layers provided on the main surfaces of the ferrite connected by electrodes arranged on top and bottom surfaces of the ferrite. The second electrode is wound at least about three turns around the ferrite. A width dimension of the outermost electrode layers of the second central electrode is greater than a width dimension of the inner electrode layers of the second central electrode.

Abstract: A nonreciprocal circuit device includes a permanent magnet, a ferrite to which the permanent magnet applies a direct-current magnetic field, first and second central electrodes arranged on the ferrite, and a circuit board. The first central electrode includes electrode layers provided on main surfaces of the ferrite connected by an electrode provided on a top surface of the ferrite. A second central electrode includes electrode layers provided on the main surfaces of the ferrite connected by electrodes arranged on top and bottom surfaces of the ferrite. The second electrode is wound at least about three turns around the ferrite. A width dimension of the outermost electrode layers of the second central electrode is greater than a width dimension of the inner electrode layers of the second central electrode.