Acoustic wave device, module, and multiplexer

1. An acoustic wave device comprising:

a first substrate;

a first terminal located on a first surface of the first substrate;

a second terminal located on the first surface of the first substrate;

a third terminal located on the first surface of the first substrate, the third terminal being a ground terminal;

series resonators located on a second surface of the first substrate opposite from the first surface and electrically connected in series with a path between the first terminal and the second terminal;

a parallel resonator located on the second surface of the first substrate, a first end of the parallel resonator being electrically connected to the path, a second end of the parallel resonator being electrically connected to the third terminal; and

a fourth terminal located on the first surface of the first substrate, at least a part of the fourth terminal overlapping with, in a thickness direction of the first substrate, at least a part of at least one of one or more first series resonators of the series resonators, each of the one or more first series resonators having both ends to which other series resonators are electrically connected,

wherein the fourth terminal does not overlap with at least one resonator of a second series resonator of the series resonators and the parallel resonator in the thickness direction of the first substrate, the second series resonator having a first end to which another series resonator is electrically connected and a second end to which no series resonator is electrically connected.

2. The acoustic wave device according to claim 1 , wherein

the fourth terminal is electrically connected to none of the first terminal, the second terminal, and the third terminal in the first substrate.

3. The acoustic wave device according to claim 1 , wherein

the fourth terminal is electrically connected to the third terminal on the second surface.

4. The acoustic wave device according to claim 1 , wherein

the fourth terminal overlaps with, in the thickness direction of the first substrate, at least one first series resonator of the one or more first series resonators so that at least one of the at least one first series resonator is located within the fourth terminal.

5. The acoustic wave device according to claim 1 , wherein

the fourth terminal overlaps with at least two of the one or more first series resonators in the thickness direction of the first substrate.

6. The acoustic wave device according to claim 1 , wherein

the first substrate includes a piezoelectric substrate having the second surface, and a support substrate having the first surface and having a thermal conductivity greater than a thermal conductivity of the piezoelectric substrate.

7. The acoustic wave device according to claim 6 , wherein

the piezoelectric substrate is in contact with the support substrate.

8. A multiplexer comprising:

an acoustic wave device including:

a first substrate,

a first terminal located on a first surface of the first substrate,

a second terminal located on the first surface of the first substrate,

a third terminal located on the first surface of the first substrate, the third terminal being a ground terminal,

series resonators located on a second surface of the first substrate opposite from the first surface and electrically connected in series with a path between the first terminal and the second terminal,

a parallel resonator located on the second surface of the first substrate, a first end of the parallel resonator being electrically connected to the path, a second end of the parallel resonator being electrically connected to the third terminal, and

a fourth terminal located on the first surface of the first substrate, at least a part of the fourth terminal overlapping with, in a thickness direction of the first substrate, at least a part of at least one of one or more first series resonators of the series resonators, each of the one or more first series resonators having both ends to which other series resonators are electrically connected, wherein the series resonators and the parallel resonator form a first filter,

the multiplexer further comprising:

a second substrate mounted on the first substrate across an air gap; and

a second filter located on a third surface of the second substrate, the third surface facing the second surface across the air gap.

9. An acoustic wave device comprising:

a first substrate;

a first terminal located on a first surface of the first substrate;

a second terminal located on the first surface of the first substrate;

a third terminal located on the first surface of the first substrate, the third terminal being a ground terminal;

series resonators located on a second surface of the first substrate opposite from the first surface and electrically connected in series with a path between the first terminal and the second terminal;

a parallel resonator located on the second surface of the first substrate, a first end of the parallel resonator being electrically connected to the path, a second end of the parallel resonator being electrically connected to the third terminal;

a fourth terminal located on the first surface of the first substrate, at least a part of the fourth terminal overlapping with, in a thickness direction of the first substrate, at least a part of at least one of one or more first series resonators of the series resonators, each of the one or more first series resonators having both ends to which other series resonators are electrically connected; and

a through electrode that is adjacent to at least one first series resonator of the one or more first series resonators, is electrically connected to none of the series resonators and the parallel resonator on the second surface, penetrates through the first substrate, and is connected to the fourth terminal.

10. An acoustic wave device comprising:

a first substrate;

a first terminal located on a first surface of the first substrate:

a second terminal located on the first surface of the first substrate;

a third terminal located on the first surface of the first substrate, the third terminal being a ground terminal;

series resonators located on a second surface of the first substrate opposite from the first surface and electrically connected in series with a path between the first terminal and the second terminal;

a parallel resonator located on the second surface of the first substrate, a first end of the parallel resonator being electrically connected to the path, a second end of the parallel resonator being electrically connected to the third terminal;

a fourth terminal located on the first surface of the first substrate, at least a part of the fourth terminal overlapping with, in a thickness direction of the first substrate, at least a part of at least one of one or more first series resonators of the series resonators, each of the one or more first series resonators having both ends to which other series resonators are electrically connected; and

a metal column that overlaps with the one or more first series resonators in the thickness direction of the first substrate, is located from the first surface to a middle part of the first substrate, and is connected to the fourth terminal.

11. A module comprising:

an acoustic wave device including:

a first substrate,

a first terminal located on a first surface of the first substrate,

a second terminal located on the first surface of the first substrate,

a third terminal located on the first surface of the first substrate, the third terminal being a ground terminal,

series resonators located on a second surface of the first substrate opposite from the first surface and electrically connected in series with a path between the first terminal and the second terminal,

a parallel resonator located on the second surface of the first substrate, a first end of the parallel resonator being electrically connected to the path, a second end of the parallel resonator being electrically connected to the third terminal, and

a fourth terminal located on the first surface of the first substrate, at least a part of the fourth terminal overlapping with, in a thickness direction of the first substrate, at least a part of at least one of one or more first series resonators of the series resonators, each of the one or more first series resonators having both ends to which other series resonators are electrically connected; and

a module substrate that has a third surface facing the first surface and a fourth surface opposite from the third surface, and includes a fifth terminal located on the third surface and bonded with the fourth terminal, a sixth terminal located on the fourth surface for connecting to an external device, and a metal pattern connecting the fifth terminal and the sixth terminal.