Front-end circuit and communication terminal apparatus

Patent metadata

Field	Value
Publication number	US-9197187-B2
Application number	US-201314072818-A
Country	US
Kind code	B2
Filing date	Nov 6, 2013
Priority date	May 9, 2011
Publication date	Nov 24, 2015
Grant date	Nov 24, 2015

Abstract

A front-end circuit includes a diplexer and an impedance conversion circuit. The diplexer includes a feeding side common port through which a high-frequency signal in a high band and a high-frequency signal in a low band are input and output, a first port through which a high-frequency signal in a high band is input and output, and a second port through which a high-frequency signal in a low band is input and output, and demultiplexes or multiplexes the high-frequency signal in a low band and the high-frequency signal in a high band. The impedance conversion circuit is connected between the second port of the diplexer and an antenna port. The first port of the diplexer is directly connected to the antenna port through a transmission line.

First claim

What is claimed is:

1. A front-end circuit comprising:
a feeding side frequency selective circuit including:
a feeding side common port through which a high-frequency signal in a first frequency band and a high-frequency signal in a second frequency band of which a frequency band is lower than the first frequency band are input or output;
a first port through which the high-frequency signal in the first frequency band is input or output; and
a second port through which the high-frequency signal in the second frequency band is input or output; wherein
the feeding side frequency selective circuit is configured to demultiplex or multiplex the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band; and
each of the first port and the second port is configured to be connected to an outside antenna element; and

an impedance conversion circuit which is provided between the second port and the outside antenna element, the impedance conversion circuit including a transformer in which a primary side coil and a secondary side coil are included, the primary side coil including a first end connected to the second port, and a second end connected to the outside antenna element, the secondary side coil including a first end connected to the ground, and a second end connected to the outside antenna element, and the primary side coil and the secondary side coil being electromagnetically coupled to each other.

2. The front-end circuit according to claim 1 , wherein:
the primary side coil of the impedance conversion circuit includes a plurality of coil conductors that are arranged so as to be interconnected in series and to mutually define a closed magnetic circuit; and
the secondary side coil of the impedance conversion circuit includes a plurality of coil conductors that are arranged so as to be interconnected in series and to mutually define a closed magnetic circuit.

3. The front-end circuit according to claim 1 , wherein respective primary side coils and secondary side coils of the impedance conversion circuit are integrally arranged in a laminate including a plurality of dielectric layers or magnetic layers.

4. The front-end circuit according to claim 1 , wherein the outside antenna element is a common antenna element.

5. The front-end circuit according to claim 1 , further comprising an antenna side frequency selective circuit including:
an antenna side common port through which the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band are input or output;
a first port through which the high-frequency signal in the first frequency band is input or output; and
a second port through which the high-frequency signal in the second frequency band is input or output; wherein
the antenna side frequency selective circuit is configured to demultiplex or multiplex the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band.

6. The front-end circuit according to claim 1 , wherein the outside antenna element includes a first outside antenna element and a second outside antenna element, the first port is connected to the first outside antenna element, and the second port is connected to the second outside antenna element.

7. A communication terminal apparatus comprising:
a front-end circuit including:
a feeding side frequency selective circuit including:
a feeding side common port through which a high-frequency signal in a first frequency band and a high-frequency signal in a second frequency band of which a frequency band is lower than the first frequency band are input or output;
a first port through which the high-frequency signal in the first frequency band is input or output; and
a second port through which the high-frequency signal in the second frequency band is input or output; wherein
the feeding side frequency selective circuit is configured to demultiplex or multiplex the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band; and

an antenna element which is connected to the second port; wherein
the front-end circuit includes an impedance conversion circuit which is provided between the second port and the antenna element, the impedance conversion circuit including a transformer in which a primary side coil and a secondary side coil are included, the primary side coil including a first end connected to the second port, and a second end connected to the antenna element, the secondary side coil including a first end connected to the ground, and a second end connected to the antenna element, and the primary side coil and the secondary side coil being electromagnetically coupled to each other.

8. The communication terminal apparatus according to claim 7 , wherein:
the primary side coil of the impedance conversion circuit includes a plurality of coil conductors that are arranged so as to be interconnected in series and to mutually define a closed magnetic circuit; and
the secondary side coil of the impedance conversion circuit includes a plurality of coil conductors that are arranged so as to be interconnected in series and to mutually define a closed magnetic circuit.

9. The communication terminal apparatus according to claim 7 , wherein the antenna element is a common antenna element.

10. The communication terminal apparatus according to claim 7 , wherein respective primary side coils and secondary side coils of the impedance conversion circuit are integrally arranged in a laminate including a plurality of dielectric layers or magnetic layers.

11. The communication terminal apparatus according to claim 7 , further comprising an antenna side frequency selective circuit including:
an antenna side common port through which the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band are input or output;
a first port through which the high-frequency signal in the first frequency band is input or output; and
a second port through which the high-frequency signal in the second frequency band is input or output; wherein
the antenna side frequency selective circuit is configured to demultiplex or multiplex the high-frequency signal in the first frequency band and the high-frequency signal in the second frequency band.

Assignees

• Murata Manufacturing Co

Inventors

• Ishizuka Kenichi
• Kato Noboru
• Ueki Noriyuki

Classifications

• H03H7/38 Primary

  Impedance-matching networks · CPC title

• H01F19/04

  Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range (resonant circuits H03H) · CPC title

• H04B1/0057

  using diplexing or multiplexing filters for selecting the desired band · CPC title

• H04B1/0458

  Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages (matching circuits in general H03H) · CPC title

• H03H7/463

  Duplexers · CPC title