Acoustic wave device

1. An acoustic wave device comprising:

first and second unbalanced terminals;

a low-frequency filter including a first longitudinally-coupled acoustic wave resonator connected to the first unbalanced terminal, the low-frequency filter having a low-frequency passband from a first minimum frequency to a first maximum frequency;

a high-frequency filter connected to the second unbalanced terminal and having a high-frequency passband from a second minimum frequency higher than the first maximum frequency to a second maximum frequency; and

first and second balanced terminals connected to the low-frequency filter and the high-frequency filter in common, the low-frequency filter further including a first one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the first balanced terminal and a second one-terminal pair acoustic wave resonator connected between the first one-terminal pair acoustic wave resonator and the first balanced terminal, an antiresonant frequency of the first one-terminal pair acoustic wave resonator and an antiresonant frequency of the second one-terminal pair acoustic wave resonator each being higher than the first maximum frequency and lower than the second minimum frequency, and the antiresonant frequency of the second one-terminal pair acoustic wave resonator being higher than the antiresonant frequency of the first one-terminal pair acoustic wave resonator.

2. The acoustic wave device of claim 1 wherein the high-frequency filter includes a second longitudinally-coupled acoustic wave resonator connected between the second unbalanced terminal and the first and second balanced terminals.

3. The acoustic wave device of claim 2 wherein the low-frequency filter further includes a third one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the second balanced terminal.

4. The acoustic wave device of claim 3 wherein the high-frequency filter further includes a fourth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the first balanced terminal.

5. The acoustic wave device claim 4 wherein the high-frequency filter further includes a fifth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the second balanced terminal.

6. An acoustic wave device comprising:

first and second unbalanced terminals;

a low-frequency filter connected to the first unbalanced terminal and having a low-frequency passband from a first minimum frequency to a first maximum frequency;

a high-frequency filter including a first longitudinally-coupled acoustic wave resonator connected to the second unbalanced terminal, the high-frequency filter having a high-frequency passband from a second minimum frequency higher than the first maximum frequency to a second maximum frequency; and

first and second balanced terminals connected to the low-frequency filter and the high-frequency filter in common, the high-frequency filter further including a first one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the first balanced terminal and a second one-terminal pair acoustic wave resonator connected between the first one-terminal pair acoustic wave resonator and the first balanced terminal, an antiresonant frequency of the first one-terminal pair acoustic wave resonator being higher than the second maximum frequency, and an antiresonant frequency of the second one-terminal pair acoustic wave resonator being higher than the antiresonant frequency of the first one-terminal pair acoustic wave resonator.

7. The acoustic wave device of claim 6 wherein the low-frequency filter includes a second longitudinally-coupled acoustic wave resonator connected between the first unbalanced terminal and the first and second balanced terminals.

8. The acoustic wave device of claim 7 wherein the high-frequency filter further includes a third one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the second balanced terminal.

9. The acoustic wave device of claim 8 wherein the low-frequency filter further includes a fourth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the first balanced terminal.

10. The acoustic wave device of claim 9 wherein the low-frequency filter further includes a fifth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the second balanced terminal.

11. An acoustic wave device comprising:

first and second unbalanced terminals;

a low-frequency filter including a first longitudinally-coupled acoustic wave resonator connected to the first unbalanced terminal, and a first one-terminal pair acoustic wave resonator connected to the first longitudinally-coupled acoustic wave resonator, the low-frequency filter having a low-frequency passband from a first minimum frequency to a first maximum frequency;

a high-frequency filter connected to the second unbalanced terminal and having a high-frequency passband from a second minimum frequency higher than the first maximum frequency to a second maximum frequency, a fractional bandwidth of the low-frequency filter being narrower than a fractional bandwidth of the high-frequency filter; and

first and second balanced terminals connected to the low-frequency filter and the high-frequency filter in common, the low-frequency filter further including a second one-terminal pair acoustic wave resonator connected between the first one-terminal pair acoustic wave resonator and the first balanced terminal and connected to the first one-terminal pair acoustic wave resonator at a first connection point, a third one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the second balanced terminal, a fourth one-terminal pair acoustic wave resonator connected between the third one-terminal pair acoustic wave resonator and the second balanced terminal and connected to the third one-terminal pair acoustic wave resonator at a second connection point, and a capacitive element connected between the first connection point and the second connection point.

12. The acoustic wave device of claim 11 wherein the high-frequency filter further includes a second longitudinally-coupled acoustic wave resonator connected between the second unbalanced terminal and the first and second balanced terminals.

13. The acoustic wave device of claim 12 wherein the high-frequency filter further includes a fifth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the first balanced terminal.

14. The acoustic wave device claim 13 wherein the high-frequency filter further includes a sixth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the second balanced terminal.

15. An acoustic wave device comprising:

first and second unbalanced terminals;

a low-frequency filter connected to the first unbalanced terminal and having a low-frequency passband from a first minimum frequency to a first maximum frequency;

a high-frequency filter including a first longitudinally-coupled acoustic wave resonator connected to the second unbalanced terminal and having a high-frequency passband from a second minimum frequency higher than the first maximum frequency to a second maximum frequency, a fractional bandwidth of the high-frequency filter being narrower than a fractional bandwidth of the low-frequency filter; and

first and second balanced terminals connected to the low-frequency filter and the high-frequency filter in common, the high-frequency filter further including a first one-terminal pair acoustic wave resonator connected between the first longitudinally-coupled acoustic wave resonator and the first balanced terminal, a second one-terminal pair acoustic wave resonator connected between the first one-terminal pair acoustic wave resonator and the first balanced terminal and connected to the first one-terminal pair acoustic wave resonator at a first connection point, a third one-terminal pair acoustic wave resonator connected to the first longitudinally- coupled acoustic wave resonator, a fourth one-terminal pair acoustic wave resonator connected between the third one-terminal pair acoustic wave resonator and the second balanced terminal and connected to the third one-terminal pair acoustic wave resonator at a second connection point, and a capacitive element connected between the first connection point and the second connection point.

16. The acoustic wave device of claim 15 wherein the low-frequency filter further includes a second longitudinally-coupled acoustic wave resonator connected between the first unbalanced terminal and the first and second balanced terminals.

17. The acoustic wave device of claim 16 wherein the low-frequency filter further includes a fifth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the first balanced terminal.

18. The acoustic wave device of claim 17 wherein the low-frequency filter further includes a sixth one-terminal pair acoustic wave resonator connected between the second longitudinally-coupled acoustic wave resonator and the second balanced terminal.