Duplexer, substrate for duplexer, and electronic apparatus

1. A duplexer comprising:

a transmit filter connected between a common terminal and a transmission terminal;

a receive filter connected between the common terminal and a reception terminal;

a capacitor connected in parallel with one of the transmit filter and the receive filter and provided between two terminals of the common terminal, the transmission terminal, and the reception terminal; and

a package including:

an insulating layer;

foot pads that include the common terminal, the transmission terminal and the reception terminal and are formed on one surface of the insulating layer; and

interconnections formed on another surface opposite to the one surface of the insulating layer,

wherein the capacitor includes two capacitor forming units that are connected in parallel with each other and are formed with at least one foot pad of the foot pads and two of the interconnections that overlap with two opposing sides of the at least one foot pad respectively.

2. The duplexer according to claim 1 , wherein the capacitor includes another capacitor forming unit that is connected in parallel with the two capacitor forming units and is formed with the at least one foot pad and another interconnection that overlaps with another side that is different from the two sides.

3. The duplexer according to claim 1 , wherein the capacitor includes other two capacitor forming units that are connected in parallel with the two capacitor forming units and are formed with the at least one foot pad and other two interconnections that overlap with other two opposing sides that are different from the two sides.

4. The duplexer according to claim 1 , wherein the two capacitor forming units have widths that are equal to each other.

5. The duplexer according to claim 1 , further comprising a phase shifting circuit that is connected in series with one of the transmit filter and the receive filter and shifts a phase of a signal in a pass band of the other one of the transmit filter and the receive filter.

6. The duplexer according to claim 1 , wherein a signal transmitted from one of the two terminals to another via the capacitor and a signal transmitted from one of the two terminals to another via the transmit filter or the receive filter have opposite phases.

7. The duplexer according to claim 1 , wherein the capacitor is connected between the reception terminal, and at least one of the common terminal and the transmission terminal.

8. The duplexer according to claim 1 , wherein the capacitor is connected between the reception terminal and the common terminal, and another capacitor is connected between the reception terminal and the transmission terminal, respectively.

9. The duplexer according to claim 1 , wherein one of the receive filter and the transmit filter includes a balun, one of the reception terminal and the transmission terminal includes a pair of balance terminals, and the capacitor is connected to one of the pair of balance terminals.

10. A duplexer comprising:

a transmit filter connected between a common terminal and a transmission terminal;

a receive filter connected between the common terminal and a reception terminal;

a capacitor connected in parallel with one of the transmit filter and the receive filter and provided between two terminals of the common terminal, the transmission terminal, and the reception terminal;

an insulating layer;

foot pads that include the common terminal, the transmission terminal and the reception terminal and are formed on one surface of the insulating layer; and

an interconnection formed on another surface opposite to the one surface of the insulating layer,

wherein:

the capacitor includes a capacitor forming unit formed with at least one foot pad of the foot pads and the interconnection formed to be included in an area where the at least one foot pad is formed; and

an area of the interconnection is smaller than an area of the at least one foot pad.

11. The duplexer according to claim 10 , wherein the interconnection includes a circular shape.

12. The duplexer according to claim 10 , further comprising:

another insulating layer provided on said another surface of the insulating layer;

a via material that connects the interconnection and another interconnection formed on a surface of said another insulating layer opposite to said another surface of the insulating layer.

13. A substrate for a duplexer comprising:

an insulating layer;

a mounting unit that mounts a transmit filter connected between a common terminal and a transmission terminal, and a receive filter connected between the common terminal and a reception terminal;

a capacitor connected in parallel with one of the transmit filter and the receive filter and provided between two terminals of the common terminal, the transmission terminal, and the reception terminal;

foot pads that include the common terminal, the transmission terminal and the reception terminal and are formed on one surface of the insulating layer; and

interconnections formed on another surface opposite to the one surface of the insulating layer,

wherein the capacitor includes two capacitor forming units that are formed with at least one foot pad of the foot pads and two of the interconnections that overlap with two opposing sides of the at least one foot pad, and are connected in parallel with each other.

14. A substrate for a duplexer comprising:

an insulating layer;

a mounting unit that mounts a transmit filter connected between a common terminal and a transmission terminal, and a receive filter connected between the common terminal and a reception terminal;

a capacitor connected in parallel with one of the transmit filter and the receive filter and provided between two terminals of the common terminal, the transmission terminal and the reception terminal;

foot pads that include the common terminal, the transmission terminal, and the reception terminal and are formed on one surface of the insulating layer; and

an interconnection formed on another surface opposite to the one surface of the insulating layer,

wherein:

the capacitor includes a capacitor forming unit formed with at least one foot pad and the interconnection formed to be included in an area where the at least one foot pad is formed; and

an area of the interconnection is smaller than an area of the at least one foot pad.

15. An electronic apparatus including a duplexer, the duplexer comprising:

a transmit filter connected between a common terminal and a transmission terminal;

a receive filter connected between the common terminal and a reception terminal;

a capacitor connected in parallel with one of the transmit filter and the receive filter and provided between two terminals of the common terminal, the transmission terminal, and the reception terminal; and

a package including:

an insulating layer;

foot pads that include the common terminal, the transmission terminal and the reception terminal and are formed on one surface of the insulating layer; and

interconnections formed on another surface opposite to the one surface of the insulating layer,

wherein the capacitor includes two capacitor forming units that are connected in parallel with each other and are formed with at least one foot pad of the foot pads and two of the interconnections that overlap with two opposing sides of the at least one foot pad respectively.