Multiplexer

1. A multiplexer comprising:

a band pass filter configured to pass a signal in a predetermined frequency band between a first terminal and a common terminal connected to an antenna; and

a band elimination filter that is configured to attenuate a signal in the predetermined frequency band between a second terminal and the common terminal and includes a plurality of resonators connected in series with a line between the second terminal and the common terminal, the plurality of resonators including a first resonator having a lowest resonant frequency among the plurality of resonators and a second resonator disposed on a side of the common terminal from the first resonator; wherein

the band pass filter includes, between the first terminal and the common terminal, a third resonator provided at a series arm and a fourth resonator provided at a parallel arm; and

all anti-resonant frequencies of the resonators are higher than a resonant frequency of the fourth resonator and lower than an anti-resonant frequency of the third resonator.

2. The multiplexer according to claim 1 , wherein the plurality of resonators include a fifth resonator having a largest capacitance value among the plurality of resonators and a sixth resonator disposed on a side of the common terminal from the fifth resonator.

3. The multiplexer according to claim 2 , wherein

the first resonator and the second resonator are adjacent to each other; and

the band elimination filter further includes a first inductor including one end connected to a node between the first resonator and the second resonator and another end to which a reference potential is supplied.

4. The multiplexer according to claim 1 , wherein

the first resonator and the second resonator are adjacent to each other; and

the band elimination filter further includes a first inductor including one end connected to a node between the first resonator and the second resonator and another end to which a reference potential is supplied.

5. The multiplexer according to claim 4 , wherein

the band elimination filter further includes, between the second resonator and the common terminal, a second inductor connected in series with the second resonator; and

an inductance value of the first inductor is larger than an inductance value of the second inductor.

6. The multiplexer according to claim 1 , wherein

the band elimination filter further includes a second inductor and a third inductor that are connected in series with the line between the second terminal and the common terminal;

the band pass filter further includes a fourth inductor connected in series with a line between the first terminal and the common terminal; and

the third inductor is disposed closer to the second inductor than to the fourth inductor.

7. The multiplexer according to claim 6 , wherein

the first resonator and the second resonator are adjacent to each other; and

the band elimination filter further includes a first inductor including one end connected to a node between the first resonator and the second resonator and another end to which a reference potential is supplied.

8. The multiplexer according to claim 1 , wherein

the band elimination filter further includes a third inductor connected in series with the line between the second terminal and the common terminal;

the band pass filter further includes a fourth inductor connected in series with a line between the first terminal and the common terminal;

the multiplexer further includes a fifth inductor connected in series with a line between the common terminal and a node between the band pass filter and the band elimination filter; and

the third inductor is disposed closer to the fifth inductor than to the fourth inductor.

9. The multiplexer according to claim 1 , wherein the plurality of resonators include a fifth resonator having a largest capacitance value among the plurality of resonators and a sixth resonator disposed on a side of the common terminal from the fifth resonator.

10. The multiplexer according to claim 1 , wherein

the first resonator and the second resonator are adjacent to each other; and

the band elimination filter further includes a first inductor including one end connected to a node between the first resonator and the second resonator and another end to which a reference potential is supplied.

11. The multiplexer according to claim 1 , wherein

the band elimination filter further includes a third inductor connected in series with the line between the second terminal and the common terminal;

the band pass filter further includes a fourth inductor connected in series with a line between the first terminal and the common terminal;

the multiplexer further includes a fifth inductor connected in series with a line between the common terminal and a node between the band pass filter and the band elimination filter; and

the third inductor is disposed closer to the fifth inductor than to the fourth inductor.

12. A communication device comprising:

the multiplexer according to claim 1 ; and

an antenna to which the multiplexer is connected; wherein

the multiplexer separates transmission signals to be transmitted from the antenna and reception signals received by the antenna.

13. The communication device according to claim 12 , further comprising:

a switch connected to the multiplexer;

a duplexer connected to the switch;

a power amplifier connected to the duplexer;

a first low noise amplifier connected to the multiplexer;

a second low noise amplifier connected to the duplexer;

a first radio frequency integrated circuit connected to the first low noise amplifier; and

a second radio frequency integrated circuit connected to the power amplifier and to the second low noise amplifier.

14. The communication device according to claim 12 , wherein the plurality of resonators include a fifth resonator having a largest capacitance value among the plurality of resonators and a sixth resonator disposed on a side of the common terminal from the fifth resonator.

15. The communication device according to claim 12 , wherein

the first resonator and the second resonator are adjacent to each other; and

the band elimination filter further includes a first inductor including one end connected to a node between the first resonator and the second resonator and another end to which a reference potential is supplied.

16. The communication device according to claim 15 , wherein

the band elimination filter further includes, between the second resonator and the common terminal, a second inductor connected in series with the second resonator; and

an inductance value of the first inductor is larger than an inductance value of the second inductor.

17. The communication device according to claim 12 , wherein

the band elimination filter further includes a second inductor and a third inductor that are connected in series with the line between the second terminal and the common terminal;

the band pass filter further includes a fourth inductor connected in series with a line between the first terminal and the common terminal; and

the third inductor is disposed closer to the second inductor than to the fourth inductor.

18. The communication device according to claim 12 , wherein

the band elimination filter further includes a third inductor connected in series with the line between the second terminal and the common terminal;

the band pass filter further includes a fourth inductor connected in series with a line between the first terminal and the common terminal;

the multiplexer further includes a fifth inductor connected in series with a line between the common terminal and a node between the band pass filter and the band elimination filter; and

the third inductor is disposed closer to the fifth inductor than to the fourth inductor.