High frequency filter, high frequency circuit, and communication device
A filter includes a series arm resonator and parallel arm circuits, in which the parallel arm circuit has a parallel arm resonator and a frequency variable circuit connected in series to each other, the frequency variable circuit has a capacitor and a switch connected parallel to each other, the other parallel arm circuit has a capacitor and a switch connected in series to each other.
1 . A high frequency filter comprising:
a series arm resonator connected between a first terminal and a second terminal;
a first parallel arm circuit connected between ground and a path that connects the series arm resonator to the second terminal; and
a second parallel arm circuit connected between ground and the path,
wherein the first parallel arm circuit comprises a parallel arm resonator and a frequency variable circuit connected in series to each other,
wherein the frequency variable circuit comprises a first capacitor and a first switch connected in parallel to each other,
wherein the second parallel arm circuit comprises a second capacitor and a second switch connected in series to each other, and
wherein:
3.2
×
10
-
1
≤
(
C
1
/
C
0
)
≤
6.25
,
0
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.08
×
10
1
×
(
C
1
/
C
0
)
2
-
3.82
×
10
-
1
×
(
C
1
/
C
0
)
+
1.98
×
10
-
1
,
F
2
(
C
1
/
C
0
)
=
3.77
×
10
-
4
×
(
C
1
/
C
0
)
4
-
6.31
×
10
-
3
×
(
C
1
/
C
0
)
3
+
4.
×
10
-
2
(
C
1
/
C
0
)
2
-
1.22
×
10
-
1
×
(
C
1
/
C
0
)
+
2.71
×
10
-
1
,
where a capacitance value of the parallel arm resonator is C0, a capacitance value of the first capacitor is C1, and a capacitance value of the second capacitor is C2.
2 . The high frequency filter according to claim 1 ,
wherein in a first mode of the high frequency filter, the first switch is in a conductive state and the second switch is in a non-conductive state, and
wherein in a second mode of the high frequency filter, the first switch is in the non-conductive state and the second switch is in the conductive state.
3 . The high frequency filter according to claim 2 ,
wherein in the first mode, the high frequency filter has a first pass band comprising a first frequency range and a second frequency range on a low-frequency side of the first frequency range, and
wherein in the second mode, the high frequency filter has a second pass band that is narrower than the first pass band and comprises the first frequency range.
4 . The high frequency filter according to claim 3 ,
wherein the first frequency range comprises either an uplink operation band of band 28B for 4G-LTE or an uplink operation band of band n28B for 5G-NR, and
wherein the second frequency range comprises either an uplink operation band of band 28A for 4G-LTE or an uplink operation band of band n28A for 5G-NR.
5 . The high frequency filter according to claim 1 , wherein:
3.2
×
10
-
1
≤
(
C
1
/
C
0
)
≤
6.25
,
0
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.73
×
10
1
×
(
C
1
/
C
0
)
2
-
3.82
×
10
-
1
×
(
C
1
/
C
0
)
+
2.18
×
10
-
1
,
F
2
(
C
1
/
C
0
)
=
6.3
×
10
-
4
×
(
C
1
/
C
0
)
4
-
9.12
×
10
-
3
×
(
C
1
/
C
0
)
3
+
4.66
×
10
-
2
(
C
1
/
C
0
)
2
-
1.12
×
10
-
1
×
(
C
1
/
C
0
)
+
2.29
×
10
-
1
.
6 . The high frequency filter according to claim 1 , wherein:
4.3
×
10
-
1
≤
(
C
1
/
C
0
)
≤
6.25
,
0
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.14
×
10
1
×
(
C
1
/
C
0
)
2
-
3.12
×
10
-
1
×
(
C
1
/
C
0
)
+
2.15
×
10
-
1
,
F
2
(
C
1
/
C
0
)
=
3.94
×
10
-
4
×
(
C
1
/
C
0
)
3
-
6.13
×
10
-
3
×
(
C
1
/
C
0
)
2
+
3.56
×
10
-
2
×
(
C
1
/
C
0
)
2
-
1.15
×
10
-
1
.
7 . The high frequency filter according to claim 1 , wherein the parallel arm resonator is a surface acoustic wave resonator or a bulk acoustic wave resonator.
8 . The high frequency filter according to claim 1 , further comprising:
a third capacitor connected in parallel to the first switch or the second switch.
9 . A high frequency filter comprising:
a first series arm circuit connected between a first terminal and a second terminal;
a frequency variable circuit connected in parallel to the first series arm circuit; and
a parallel arm resonator connected between ground and a path that connects the first terminal to the second terminal,
wherein the first series arm circuit comprises a series arm resonator and a second series arm circuit connected in series to each other,
wherein the frequency variable circuit comprises a first capacitor and a first switch connected in series to each other,
wherein the second series arm circuit comprises a second capacitor and a second switch connected in parallel to each other, and
wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
1.44
,
2.62
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
5.23
×
(
C
1
/
C
0
-
0.15
)
-
1.72
,
F
2
(
C
1
/
C
0
)
=
-
2.98
×
(
C
1
/
C
0
)
3
+
1.19
×
10
1
×
(
C
1
/
C
0
)
2
-
1.68
×
10
1
×
(
C
1
/
C
0
)
+
1.11
×
10
1
,
where a capacitance value of the series arm resonator is C0, a capacitance value of the first capacitor is C1, and a capacitance value of the second capacitor is C2.
10 . The high frequency filter according to claim 9 , wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
1.31
,
3.66
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
5.88
×
(
C
1
/
C
0
)
-
1.68
,
F
2
(
C
1
/
C
0
)
=
-
3.43
×
(
C
1
/
C
0
)
3
+
1.52
×
10
1
×
(
C
1
/
C
0
)
2
-
2.16
×
10
1
×
(
C
1
/
C
0
)
+
1.36
×
10
1
.
11 . The high frequency filter according to claim 9 , wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
8.5
×
10
-
1
,
5.23
≤
C
2
/
C
0
,
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
-
4.66
×
(
C
1
/
C
0
)
3
+
8.86
×
10
1
×
(
C
1
/
C
0
)
2
-
6.26
×
10
1
×
(
C
1
/
C
0
)
+
2.27
×
10
1
,
F
2
(
C
1
/
C
0
)
=
4.68
×
(
C
1
/
C
0
)
-
1.47
.
12 . A high frequency filter comprising:
a first series arm circuit connected between a first terminal and a second terminal;
a frequency variable circuit; and
a parallel arm resonator connected between ground and a path that connects the first terminal to the second terminal,
wherein the first series arm circuit comprises a series arm resonator and a second series arm circuit connected in series to each other,
wherein the frequency variable circuit comprises a first capacitor and a first switch connected in parallel to the series arm resonator and connected in series to each other,
wherein the second series arm circuit comprises a second capacitor and a second switch connected in parallel to each other, and
wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
1.83
,
5.23
≤
C
2
/
C
0
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.19
×
10
1
×
(
C
1
/
C
0
-
0.25
)
-
7.71
×
10
-
1
,
F
2
(
C
1
/
C
0
)
=
-
1.19
×
(
C
1
/
C
0
)
3
+
5.39
×
10
1
×
(
C
1
/
C
0
)
2
-
9.19
×
(
C
1
/
C
0
)
+
1.1
×
10
1
,
where a capacitance value of the series arm resonator is C0, a capacitance value of the first capacitor is C1, and a capacitance value of the second capacitor is C2.
13 . The high frequency filter according to claim 12 ,
wherein in a first mode of the high frequency filter, the first switch is in a conductive state and the second switch is in a non-conductive state, and
wherein in a second mode of the high frequency filter, the first switch is in the non-conductive state and the second switch is in the conductive state.
14 . The high frequency filter according to claim 13 ,
wherein in the second mode, the high frequency filter has a first pass band comprising a first frequency range and a second frequency range on a high-frequency side of the first frequency range, and
wherein in the first mode, the high frequency filter has a second pass band that is narrower than the first pass band and comprises the first frequency range.
15 . The high frequency filter according to claim 14 ,
wherein the first frequency range comprises either an uplink operation band of band 28A for 4G-LTE or an uplink operation band of band n28A for 5G-NR, and
wherein the second frequency range comprises either an uplink operation band of band 28B for 4G-LTE or an uplink operation band of band n28B for 5G-NR.
16 . The high frequency filter according to claim 12 , wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
1.7
,
5.76
≤
C
2
/
C
0
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.32
×
(
C
1
/
C
0
)
-
1.3
,
F
2
(
C
1
/
C
0
)
=
-
2.98
×
(
C
1
/
C
0
)
3
+
1.09
×
10
1
×
(
C
1
/
C
0
)
2
-
1.51
×
(
C
1
/
C
0
)
+
1.4
×
10
1
.
17 . The high frequency filter according to claim 12 , wherein:
5.
×
10
-
2
≤
(
C
1
/
C
0
)
≤
1.37
,
7.32
≤
C
2
/
C
0
F
1
(
C
1
/
C
0
)
≤
C
2
/
C
0
≤
F
2
(
C
1
/
C
0
)
,
F
1
(
C
1
/
C
0
)
=
1.08
×
10
1
×
(
C
1
/
C
0
)
-
9.93
×
10
-
1
,
F
2
(
C
1
/
C
0
)
=
-
8.37
×
(
C
1
/
C
0
)
3
+
2.66
×
10
1
×
(
C
1
/
C
0
)
2
-
3.05
×
10
1
×
(
C
1
/
C
0
)
+
2.04
×
10
1
.
18 . The high frequency filter according to claim 12 , wherein the series arm resonator is a surface acoustic wave resonator or a bulk acoustic wave resonator.
19 . A high frequency circuit comprising:
the high frequency filter according to claim 1 ;
a first filter; and
a switch circuit comprising a common terminal, a first selection terminal, and a second selection terminal, and configured to switch connection and disconnection of the common terminal between the first selection terminal and the second selection terminal,
wherein the high frequency filter and the first filter are connected to the second terminal.
20 . A communication device comprising:
a signal processing circuit configured to process a high frequency signal; and
the high frequency circuit according to claim 19 configured to pass the high frequency signal between the signal processing circuit and an antenna.