US 11,115,003 B2 · Acoustic wave device, multiplexer, high-frequency front end circuit, and communication apparatus

Abstract

In an acoustic wave device, an antenna end resonator electrically closest to a first terminal is a first acoustic wave resonator. In each of the first acoustic wave resonator and a second acoustic wave resonator, a thickness of a piezoelectric layer is equal to or less than about 3.5λ. A cut angle of the piezoelectric layer of the first acoustic wave resonator is within a range of θB±4°. The cut angle of the piezoelectric layer of the second acoustic wave resonator has a larger difference from θB (°) than the cut angle of the piezoelectric layer of the first acoustic wave resonator.

An acoustic wave device that is provided between a first terminal defining an antenna terminal and a second terminal different from the first terminal, the acoustic wave device comprising:

a plurality of acoustic wave resonators;
wherein
the plurality of acoustic wave resonators include:
a plurality of series arm resonators provided on a first path connecting the first terminal and the second terminal;
and
a plurality of parallel arm resonators provided on a plurality of second paths connecting a plurality of nodes on the first path and ground, respectively;
when an acoustic wave resonator that is electrically closest to the first terminal among the plurality of acoustic wave resonators is an antenna end resonator;
the antenna end resonator is a first acoustic wave resonator;
and
at least one acoustic wave resonator other than the antenna end resonator among the plurality of acoustic wave resonators is a second acoustic wave resonator;
each of the first acoustic wave resonator and the second acoustic wave resonator includes:
a piezoelectric layer;
an IDT electrode provided on the piezoelectric layer and including a plurality of electrode fingers;
a high-acoustic-velocity layer located on a side opposite to the IDT electrode with the piezoelectric layer interposed therebetween and in which an acoustic velocity of a bulk wave propagating in the high-acoustic-velocity layer is higher than an acoustic velocity of an acoustic wave propagating in the piezoelectric layer;
and
a low-acoustic-velocity film provided between the high-acoustic-velocity layer and the piezoelectric layer and in which an acoustic velocity of a bulk wave propagating in the low-acoustic-velocity film is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric layer;
a thickness of the piezoelectric layer is equal to or less than about 3.5λ where a wavelength of an acoustic wave, which is determined by an electrode finger cycle as a cycle of the plurality of electrode fingers of the IDT electrode, is λ;
a cut angle of the piezoelectric layer of the first acoustic wave resonator is within a range of about θB±4° with reference to θB (°) obtained by an equation (1) where the wavelength is λ (μm), a thickness of the IDT electrode is TIDT (μm), a specific gravity of the IDT electrode is ρ (g/cm3), a duty ratio as a value obtained by dividing a width of the electrode fingers by a half value of the electrode finger cycle is Du, a thickness of the piezoelectric layer is TLT (μm), and a thickness of the low-acoustic-velocity film is TVL (μm);
θ
B
=
4
⁢
3
.
0
⁢
9
-
2
⁢
7
.
5
×
(
T
IDT
λ
×
ρ
-
0.1956
)
-
19.2
×
(
D
u
-
0
⁢
.5
)
+
17.4578
×
(
T
LT
λ
-
0
.
3
⁢
5
)
+
5
.
6
⁢
1
⁢
9
×
(
T
V
⁢
L
λ
-
0
⁢
.3
)
+
3
⁢
2
.
6
⁢
6
×
{
(
T
L
⁢
T
λ
-
0
.
3
⁢
5
)
2
-
0
.
0
⁢
1
⁢
25
}
+
2
⁢
4
.
6
⁢
3
×
(
T
L
⁢
T
λ
-
0
.
3
⁢
5
)
×
(
T
VL
λ
-
0.3
)
;
Equation
⁢
⁢
(
1
)
and
a cut angle of the piezoelectric layer of the second acoustic wave resonator has a larger difference from θB (°) than the cut angle of the piezoelectric layer of the first acoustic wave resonator.

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Acoustic wave device, multiplexer, high-frequency front end circuit, and communication apparatus

Life of this patent

Acoustic wave device, multiplexer, high-frequency front end circuit, and communication apparatus

Life of this patent

Abstract

Claims20