WO2018123545A1

WO2018123545A1 - Multiplexer

Info

Publication number: WO2018123545A1
Application number: PCT/JP2017/044421
Authority: WO
Inventors: 陽平小中
Original assignee: 株式会社村田製作所
Priority date: 2016-12-28
Filing date: 2017-12-11
Publication date: 2018-07-05
Also published as: CN209823720U

Abstract

Provided is a multiplexer (1) which is connected to a ladder filter through a common terminal (20) and is capable of improving transmission characteristics of a filter for low frequency bandwidth. The multiplexer is provided with: a filter (13); and a filter (14) comprising a ladder filter for passing a high frequency signal in a frequency bandwidth higher than that of the filter (13). The filter (14) has series arm resonators (32a to 32e) and parallel arm resonators (34a to 34d), and an inductor (36a) having an inductance value larger than the inductance value between the parallel arm resonator (34d) and the ground is connected between the parallel arm resonator (34a) and the ground.

Description

Multiplexer

The present invention relates to a multiplexer.

In recent years, high-frequency modules such as duplexers and multiplexers in which a plurality of filter circuits are formed on one chip have been developed in order to reduce the size and multiband of high-frequency modules for communication. As a filter used in such a high-frequency module, for example, a ladder filter in which a series arm resonator and a parallel arm resonator are combined is used (see, for example, Patent Document 1).

In the ladder type filter described in Patent Document 1, the resonance frequency of the series arm resonator and the antiresonance frequency of the parallel arm resonator are matched, and the inductor is connected between the parallel arm resonator of the ladder type filter and the ground. Thus, a filter having good loss characteristics and high attenuation characteristics is realized.

JP-A-5-183380

However, in the multiplexer in which a plurality of filters are connected to the common terminal on the antenna end side, when the ladder type filter described in Patent Document 1 is used as a filter corresponding to a high frequency band, the parallel arm resonator is connected to the ground. In some cases, the loss characteristic of the filter corresponding to the low frequency band may be deteriorated by the inductor connected to.

In view of the above problems, an object of the present invention is to provide a multiplexer capable of improving the pass characteristics of a filter corresponding to a low frequency band connected to a ladder type filter corresponding to a high frequency band at a common terminal. To do.

In order to achieve the above object, one aspect of a multiplexer according to the present invention includes a first filter that passes a high-frequency signal and a ladder filter that passes a high-frequency signal in a higher frequency band than the first filter. A second filter, wherein the second filter is connected in series between a common terminal to which the first filter and the second filter are connected, and an input / output terminal opposite to the common terminal. And a plurality of parallel arm resonators connected between a node to which the series arm resonator is connected and a ground, and the plurality of parallel arm resonators. Among the first parallel arm resonators disposed on the side farthest from the common terminal and the second parallel arm resonators disposed on the most common terminal side, the first parallel arm resonator And ground , The first inductor is greater inductance than the inductance value between the second parallel arm resonator and the ground are connected.

In the second filter that is a ladder filter, the inductance value between the first parallel arm resonator and the ground and the inductance value between the second parallel arm resonator and the ground are the frequencies of the second filter. Affects the formation of bands. The inductance value between the second parallel arm resonator close to the common terminal and the ground is more than the inductance value between the first parallel arm resonator far from the common terminal and the ground. The influence on the pass characteristics of the filter is large. Therefore, the inductance value of the first inductor connected between the first parallel arm resonator far from the common terminal and the ground is made larger than the inductance value between the second parallel arm resonator and the ground. Accordingly, it is possible to improve the pass characteristic of the first filter corresponding to the frequency band lower than that of the second filter without deteriorating the pass characteristic of the second filter.

Further, a second inductor having an inductance value smaller than that of the first inductor may be connected between the second parallel arm resonator and the ground.

Thereby, since the inductance value of the first inductor is larger than the inductance value of the second inductor, it corresponds to a lower frequency band than the second filter without deteriorating the pass characteristic of the second filter. The pass characteristic of the first filter can be improved.

Also, an inductor may not be connected between the second parallel arm resonator and the ground.

In this configuration, it can be considered that an inductor having an inductance value of 0 is arranged between the second parallel arm resonator and the ground. Therefore, the inductance value of the first inductor is larger than the inductance value between the second parallel arm resonator and the ground. Thereby, the pass characteristic of the 1st filter corresponding to a lower frequency band than the 2nd filter can be improved, without degrading the pass characteristic of the 2nd filter.

Further, at least one other filter in which a frequency band of a high-frequency signal to be passed is different from that of the first filter and the second filter may be further provided.

Thereby, even when a plurality of filters are arranged in the multiplexer, it is possible to improve the pass characteristics of the filter corresponding to a lower frequency band than the second filter among the plurality of filters.

Further, the second filter may be a filter that allows a high-frequency signal in the highest frequency band to pass among the plurality of filters provided in the multiplexer.

Thereby, since the second filter corresponds to the highest frequency band among the plurality of filters, the pass characteristics of the filter are compared with all other filters corresponding to the frequency band lower than the second filter. Can be improved.

The inductance value of the second inductor may be 1.8 nH or less.

As a result, the loss deterioration amount of the second filter can be set to 0.03 dB or less, so that the influence of the second filter on the frequency band of the other filter is reduced and the pass characteristics of the other filter are improved. be able to.

According to the present invention, it is possible to provide a multiplexer capable of improving the pass characteristic of a filter corresponding to a low frequency band connected to a ladder filter at a common terminal.

FIG. 1 is a conceptual diagram illustrating a configuration of a multiplexer according to an embodiment. 2A and 2B are schematic diagrams illustrating a configuration of a resonator in the multiplexer according to the embodiment, in which FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along an alternate long and short dash line illustrated in FIG. FIG. 3 is a diagram illustrating a change in impedance of the ladder filter when the inductance value of the inductor connected between the parallel arm resonator of the ladder filter and the ground is changed in the multiplexer according to the embodiment. is there. FIG. 4A is a diagram illustrating a pass characteristic of the second filter in the multiplexer according to the embodiment. FIG. 4B is a diagram illustrating a pass characteristic of the second filter in the multiplexer according to the embodiment. FIG. 5A is a diagram illustrating a pass characteristic of the first filter in the multiplexer according to the embodiment. FIG. 5B is a diagram illustrating pass characteristics of other filters in the multiplexer according to the embodiment. FIG. 5C is a diagram illustrating a pass characteristic of another filter in the multiplexer according to the embodiment. FIG. 6 is a diagram illustrating the relationship between the loss deterioration amount and the inductance value of the multiplexer according to the embodiment. FIG. 7 is a conceptual diagram showing a configuration of a multiplexer according to a modified example.

Hereinafter, embodiments of the present invention will be described. Note that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangement positions and connection forms of components shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

Each figure is a schematic diagram and is not necessarily shown strictly. In each figure, substantially the same components are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

(Embodiment)
[1. Configuration of multiplexer]
The multiplexer 1 according to the present embodiment is, for example, a multiplexer including a plurality of bands of transmission filters and reception filters. The multiplexer 1 also includes a duplexer.

FIG. 1 is a schematic configuration diagram showing a configuration of a multiplexer 1 according to the present embodiment. As shown in FIG. 1, the multiplexer 1 includes

filters

11, 12, 13, and 14 having different frequency bands. The

filters

11, 12, 13 and 14 are each connected to a common terminal 20 connected to the antenna 2. The opposite side of the

filters

11, 12, 13, and 14 to the common terminal 20 side is connected to input /

output terminals

21, 22, 23, and 24, respectively.

The filter 11 is a transmission filter having a band 3 transmission band (1710-1785 MHz) of the LTE (Long Term Evolution) standard as a pass band, for example.

The filter 12 is a reception filter having a band 3 reception band (1805 to 1880 MHz) as a pass band, for example.

The filter 13 is, for example, a transmission filter having a band 1 transmission band (1920-1980 MHz) as a pass band. In the present embodiment, the filter 13 is a first filter.

The filter 14 is, for example, a reception filter having a band 1 reception band (2110-2170 MHz) as a pass band. The filter 14 is a filter used in a higher frequency band than the

filters

11, 12 and 13. That is, the filter 14 is a filter that passes a high-frequency signal in the highest frequency band among the plurality of filters provided in the multiplexer 1. The filter 14 includes a ladder type filter including five series arm resonators and four parallel arm resonators. In the present embodiment, the filter 14 is a second filter.

In the present embodiment, the

filters

11 and 12 are other filters. The

filters

11 and 12 are different from the filter 13 and the filter 14 in the frequency band of the high-frequency signal to be passed. The

filters

11, 12, and 13 are not limited to ladder filters, and may be filters having other configurations including at least one parallel arm resonator and series arm resonator.

As shown in FIG. 1, in the filter 14, five

series arm resonators

32 a, 32 b, 32 c, 32 d and 32 e are arranged in series in this order from the common terminal 20 between the common terminal 20 and the input / output terminal 24. It is connected. One end of the parallel arm resonator 34a is connected to a node between the

series arm resonators

32a and 32b. Further, an inductor 36a is connected between the other end of the parallel arm resonator 34a and the ground. In the present embodiment, the parallel arm resonator 34a is a second parallel arm resonator. The inductor 36a is a second inductor.

Similarly, one end of the parallel arm resonator 34b is connected to the node between the series arm resonators 32b and 32c, and one end of the parallel arm resonator 34c is connected to the node between the series arm resonators 32c and 32d. One end of a parallel arm resonator 34d is connected to a node between the

arm resonators

32d and 32e.

Inductors

36b, 36c, and 36d are connected between the other ends of the

parallel arm resonators

34b, 34c, and 34d and the ground, respectively. In the present embodiment, the parallel arm resonator 34d is a first parallel arm resonator. The inductor 36d is a first inductor.

The

series arm resonators

32a, 32b, 32c, 32d and 32e, the

parallel arm resonators

34a, 34b, 34c and 34d, and the

inductors

36a, 36b, 36c and 36d as described above make the filter 14 as a ladder filter. It is configured.

Here, the inductance values L1, L2, L3, and L4 of the

inductors

36a, 36b, 36c, and 36d are, for example, L1 = 2.00 nH, L2 = 1.45 nH, L3 = 1.64 nH, and L4 = 2.50 nH, respectively. It is. That is, the relationship between the inductance values of the inductor 36a and the inductor 36d is L1 <L4. In the filter 14, the inductor 36 a connected to the parallel arm resonator 34 a arranged closest to the common terminal 20 and the inductor 36 d connected to the parallel arm resonator 34 d arranged closest to the input / output terminal 24 are used. Since the frequency band of the filter 14 is formed, the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d are set larger than the inductance value L2 of the inductor 36b and the inductance value L3 of the inductor 36c. The inductance values L1, L2, L3, and L4 of the

inductors

36a, 36b, 36c, and 36d are not limited to the values described above, and may be other values.

The

series arm resonators

32a, 32b, 32c, 32d, and 32e, and the

parallel arm resonators

34a, 34b, 34c, and 34d are resonators formed of, for example, surface acoustic wave filters. FIG. 2 is a schematic diagram showing the configuration of the surface acoustic wave filter 100 that constitutes the

series arm resonators

32a, 32b, 32c, 32d, and 32e and the

parallel arm resonators

34a, 34b, 34c, and 34d. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along the one-dot chain line shown in FIG. The

series arm resonators

32a, 32b, 32c, 32d, and 32e and the

parallel arm resonators

34a, 34b, 34c, and 34d have the same configuration, but are not limited thereto.

As shown in FIGS. 2A and 2B, the surface acoustic wave filter 100 includes a piezoelectric substrate 106 and comb-shaped IDT (InterDigital Transducer)

electrodes

101a and 101b.

The piezoelectric substrate 106 is made of, for example, a single crystal of LiNbO ₃ cut at a predetermined cut angle. In the piezoelectric substrate 106, surface acoustic waves propagate in a predetermined direction.

2A, a pair of

IDT electrodes

101a and 101b facing each other are formed on the piezoelectric substrate 106. As shown in FIG. The IDT electrode 101a includes a plurality of electrode fingers 102a that are parallel to each other and a bus bar electrode 104a that connects the plurality of electrode fingers 102a. The IDT electrode 101b includes a plurality of electrode fingers 102b that are parallel to each other and a bus bar electrode 104b that connects the plurality of electrode fingers 102b. The IDT electrode 101a and the IDT electrode 101b include a plurality of electrode fingers 102b of the other IDT electrode 101b between each of the plurality of electrode fingers 102a of the IDT electrode 101a of the IDT electrode 101a and the IDT electrode 101b. Is arranged.

Also, the IDT electrode 101a and the IDT electrode 101b have a structure in which an adhesion layer 107 and a main electrode layer 108 are laminated as shown in FIG.

The adhesion layer 107 is a layer for improving the adhesion between the piezoelectric substrate 106 and the main electrode layer 108. As a material, for example, NiCr is used. The film thickness of the adhesion layer 17 is, for example, 10 nm.

The main electrode layer 108 is made of, for example, Pt as a material. The main electrode layer 108 has a single layer structure composed of one layer, and has a film thickness of, for example, 83 nm. Note that the main electrode layer 108 may have a stacked structure in which a plurality of layers are stacked.

The protective layer 109 is formed so as to cover the

IDT electrodes

101a and 101b. The protective layer 109 is a layer for the purpose of protecting the main electrode layer 108 from the external environment, adjusting frequency temperature characteristics, and improving moisture resistance, for example, a film containing silicon dioxide as a main component. . The protective layer 109 may have a single layer structure or a laminated structure.

Note that the materials constituting the adhesion layer 107, the main electrode layer 108, and the protective layer 109 are not limited to the materials described above. Furthermore, the

IDT electrodes

101a and 101b do not have to have the above laminated structure. The

IDT electrodes

101a and 101b may be made of, for example, a metal or an alloy such as Ti, Al, Cu, Pt, Au, Ag, or Pd, and a plurality of layers made of the above metals or alloys are laminated. It may also be configured with a stacked structure. Further, the protective layer 109 may not be formed.

In FIG. 2, λ is the repetition pitch of the plurality of

electrode fingers

102a and 102b constituting the

IDT electrodes

101a and 101b, D is the cross width of the

IDT electrodes

101a and 101b, W is the width of the

electrode fingers

102a and 102b, and S is The width h between the

electrode fingers

102a and 102b indicates the height of the

IDT electrodes

101a and 101b.

In addition, the structure of the surface acoustic wave filter 100 is not limited to the structure described in (a) and (b) of FIG. For example, the

IDT electrodes

101a and 101b may not be a laminated structure of metal films but may be a single layer of metal films.

Filters

11, 12, and 13 are not limited to ladder filters, and may be filters having other configurations.

[2. High frequency characteristics of multiplexer]
Hereinafter, the high frequency characteristics of the multiplexer 1 will be described.

The impedance characteristics of the parallel arm resonator when the inductance value of the inductor connected between each of the parallel arm resonators and the ground is changed will be described. FIG. 3 is a diagram illustrating a change in impedance of the parallel arm resonator when the inductance value of the inductor connected between the parallel arm resonator of the ladder filter and the ground is changed.

In general, when the inductance value of the inductor connected between the parallel arm resonator and the ground in the ladder filter is changed to 0.5 nH, 1.0 nH, 2.0 nH, and 4.0 nH, as shown in FIG. As the inductance value increases, the resonance point of the parallel arm resonator moves to the lower frequency side, and the impedance Z deteriorates. In FIG. 3, the Q value is constant at Q = 20. Therefore, in the ladder type filter, the pass characteristic of the ladder type filter itself deteriorates as the inductance value of the inductor connected between the parallel arm resonator and the ground increases. In addition, since the amount of signal leakage to other filters having a low frequency band connected to the ladder filter at the common terminal increases, it can be considered that the characteristics of the other filters also deteriorate.

Here, in the ladder type filter, the inductor connected to the parallel arm resonator disposed at the position closest to the common terminal and the parallel arm resonator disposed at the position closest to the input / output terminal opposite to the common terminal are connected. The connected inductor is an inductor that greatly influences the determination of the frequency band of the ladder filter. Replacing the inductor values of these inductors does not affect the pass characteristics of the ladder filter itself. However, since the inductor connected to the parallel arm resonator arranged closest to the common terminal is arranged close to other filters connected to the ladder filter, the inductance value of this inductor is large. It is thought that it has a great influence on the pass characteristics of other filters.

Thus, in the configuration of the filter 14 of the multiplexer 1 according to the present embodiment, the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is L1 <L4, thereby degrading the pass characteristic of the filter 14. And the pass characteristics of the

other filters

11, 12 and 13 can be improved.

Hereinafter, in the multiplexer 1, the pass characteristics when the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is L4 <L1 and L1 <L4 will be described. 4A and 4B are diagrams showing the pass characteristics of the filter 14 in the multiplexer 1. FIG. 5A is a diagram illustrating the pass characteristic of the filter 13 in the multiplexer 1. FIG. 5B is a diagram illustrating the pass characteristic of the filter 11 in the multiplexer 1. FIG. 5C is a diagram illustrating pass characteristics of the filter 12 in the multiplexer 1.

When the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is L4 <L1, the inductance values of the

inductors

36a, 36b, 36c, and 36d are L1 = 2.50 nH and L2 = 1.45 nH, respectively. L3 = 1.64 nH and L4 = 2.00 nH. When the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is L1 <L4, the inductance values L1, L2, L3, and L4 of the

inductors

36a, 36b, 36c, and 36d are set to L1 = 2.00 nH, L2 = 1.45 nH, L3 = 1.64 nH, and L4 = 2.50 nH. The

parallel arm resonators

34a and 34d have the same capacity by adjusting the crossing width and logarithm of the IDT electrodes constituting the

parallel arm resonators

34a and 34d.

Further, in FIGS. 4A to 5C, the pass characteristic when L4 <L1 is shown by a solid line, and the pass characteristic when L1 <L4 is shown by a broken line.

As shown in FIGS. 4A and 4B, in the filter 14, even if the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is changed from L4 <L1 to L1 <L4, the passband (2110 of the filter 14). It can be seen that the pass characteristics at −2170 MHz have hardly changed.

Further, as shown in FIG. 5A, in the filter 13, when the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is changed from L4 <L1 to L1 <L4, the pass band (1920-1980 MHz) of the filter 13 is obtained. It can be seen that the insertion loss at is reduced and the pass characteristics are improved.

Similarly, as shown in FIG. 5B, in the filter 11, when the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is changed from L4 <L1 to L1 <L4, the passband (1710-1785 MHz) of the filter 11 is obtained. ) Is reduced, and the pass characteristics are improved. As shown in FIG. 5C, in the filter 12, when the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d is changed from L4 <L1 to L1 <L4, the passband (1805 to 1880 MHz) of the filter 12 is obtained. The insertion loss is reduced, and the pass characteristics are improved.

Thus, by setting the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d to L1 <L4, the pass characteristics of the

filters

11, 12, and 13 are improved without deteriorating the pass characteristics of the filter 14. can do.

Here, an example of the inductance value L1 of the inductor 36a will be described. FIG. 6 is a diagram illustrating the relationship between the loss deterioration amount of the high frequency module and the inductance value L1 of the inductor 36a.

FIG. 6 shows the loss deterioration amount with respect to the inductance value of the inductor 36a when the Q value (resonance sharpness) is infinite, 40, and 20. As shown in FIG. 6, as the inductance value L1 of the inductor 36a is increased by 0 to 0.2nH, the loss deterioration amount in the parallel arm resonator 34a increases. It can also be seen that the loss degradation amount increases as the Q value decreases.

Here, in consideration of measurement variations and the like, the loss deterioration amount is preferably, for example, 0.03 dB or less. This is because if the loss deterioration amount is 0.03 dB or less, the influence of the filter 14 on the frequency bands of the

other filters

11, 12, and 13 can be reduced.

According to FIG. 6, the inductance value L1 of the inductor 36a at which the loss degradation amount is 0.03 dB or less is L1 ≦ 1.8 nH, for example, when Q is 20. Since the inductor 36a is the inductor arranged closest to the common terminal 20 in the filter 14, the inductance value L1 of the inductor 36a greatly affects the

other filters

11, 12, and 13. Therefore, it is preferable that the inductance value L1 of the inductor 36a having the greatest influence on the

other filters

11, 12, and 13 is L1 ≦ 1.8 nH. Thereby, the loss degradation amount of the filter 14 can be 0.03 dB or less with a small influence on the frequency bands of the

other filters

11, 12, and 13.

Note that the Q value of commonly used inductors is 20 to 40. According to FIG. 6, when the Q value is 20 to 40, if the inductance value L1 of the inductor 36a on the common terminal 20 side is L1 ≦ 1.8 nH, the loss deterioration amount is at least 0.03 dB or less. .

In addition, since the inductor 36a is connected to the parallel arm resonator 34a disposed on the most common terminal 20 side of the filter 14 that is a ladder type filter, the filter 14 is connected to the series arm resonator in the case of a ladder type filter. The number and arrangement of the parallel arm resonators may be changed. Even in this case, by setting the inductance value L1 of the inductor 36a connected to the parallel arm resonator 34a arranged closest to the common terminal 20 to L1 ≦ 1.8 nH, the filter 14 is connected to the

filters

11, 12, and 13. The influence on the frequency band can be reduced.

[3. Effect]
According to the multiplexer 1 according to the present embodiment, by setting the relationship between the inductance value L1 of the inductor 36a and the inductance value L4 of the inductor 36d to L1 <L4, it is common with the filter 14 without changing the pass characteristic of the filter 14. Of the

other filters

11, 12, and 13 connected at the terminal 20, the pass characteristic of the filter corresponding to a frequency band lower than that of the filter 14 can be improved.

Further, when the filter 14 is a filter corresponding to the highest frequency band among the plurality of

filters

11, 12, 13, and 14 arranged in the multiplexer 1, another filter corresponding to a frequency band lower than the filter 14 is used. The pass characteristics of all the

filters

11, 12 and 13 can be improved.

Further, by setting the inductance value L1 of the inductor 36a to 1.8 nH or less, the loss deterioration amount of the filter 14 can be set to 0.03 dB or less. Thereby, the influence which the filter 14 has with respect to the frequency band of the

other filters

11, 12, and 13 can be made small, and the pass characteristic of the

filters

11, 12, and 13 can be improved.

In the above-described embodiment, the filter 14 in the multiplexer 1 is a reception filter having a band 1 reception band (2110-2170 MHz) as a pass band, but is not limited thereto. The filter 14 may be a reception filter having another frequency band as a reception band as long as it is not a filter corresponding to the lowest frequency band among the plurality of filters constituting the multiplexer 1. The filter 14 is not limited to a reception filter, and may be a transmission filter or a transmission / reception filter that can perform both transmission and reception.

In the above-described embodiment, the filter 14 that is a ladder filter connects five

series arm resonators

32a, 32b, 32c, 32, and 32e and four

parallel arm resonators

34a, 34b, 34c, and 34d. However, the present invention is not limited to this, and the number of series arm resonators and parallel arm resonators may be changed as appropriate. The filter 14 may be configured to include at least one series arm resonator and a plurality (two or more) parallel arm resonators.

Further, in the filter 14, a series arm resonator may be disposed at a position closest to the common terminal 20, or a parallel arm resonator may be disposed. In addition, a series arm resonator may be disposed at a position closest to the input / output terminal 24 on the side opposite to the common terminal 20, or a parallel arm resonator may be disposed.

(Modification)
Hereinafter, modifications of the embodiment will be described. The multiplexer 1a according to this modification is different from the multiplexer 1 according to the embodiment in that the parallel arm resonator 34a arranged closest to the common terminal 20 in the filter 14a is directly connected to the ground.

FIG. 7 is a conceptual diagram showing the configuration of the multiplexer 1a according to this modification. As shown in FIG. 7, the multiplexer 1a includes

filters

11, 12, 13, and 14a. The configurations of the

filters

11, 12 and 13 are the same as the configurations of the

filters

11, 12 and 13 in the multiplexer 1 shown in the first embodiment, and thus detailed description thereof is omitted.

The filter 14a is a ladder type filter, and an inductor 36d is connected between the parallel arm resonator 34d arranged closest to the input / output terminal 24 and the ground. Further, the parallel arm resonator 34a arranged closest to the common terminal 20 is directly connected to the ground. That is, as compared with the multiplexer 1 shown in the above-described embodiment, the inductor 36a shown in the embodiment is not connected between the parallel arm resonator 34a and the ground.

In this configuration, it can be considered that the inductor 36a having an inductance value of 0 is arranged between the parallel arm resonator 34a and the ground. Therefore, the inductance value L4 of the inductor 36d connected between the parallel arm resonator 34d disposed closest to the input / output terminal 24 and the ground is the inductance value between the parallel arm resonator 34a and the ground. It is a value larger than (inductance value L1 in the above-described embodiment). Therefore, the multiplexer 1a can be considered to have a configuration satisfying L1 <L4, similarly to the multiplexer 1 described in the above-described embodiment.

Thus, even if the multiplexer 1a has a configuration in which the parallel arm resonator 34a and the ground are directly connected and no inductor is provided between the parallel arm resonator 34a and the ground, the pass characteristic of the filter 14a is deteriorated. Therefore, the pass characteristics of the

filters

11, 12 and 13 can be improved.

(Other embodiments)
In addition, this invention is not limited to the structure described in embodiment mentioned above, For example, you may add a change suitably like the modification shown below.

For example, in the above-described embodiment, in the above-described embodiment, the filter 14 in the multiplexer 1 is a reception filter having a band 1 reception band (2110-2170 MHz) as a pass band, but is not limited thereto. The filter 14 may be a reception filter having another frequency band as a reception band as long as it is not a filter corresponding to the lowest frequency band among the plurality of filters constituting the multiplexer 1. The filter 14 is not limited to a reception filter, and may be a transmission filter or a transmission / reception filter that can perform both transmission and reception.

series arm resonators

32a, 32b, 32c, 32, and 32e and four

parallel arm resonators

In addition, the form obtained by making various modifications conceived by those skilled in the art with respect to the above-described embodiments and modifications, or the components and functions in the above-described embodiments and modifications without departing from the spirit of the present invention. Forms realized by arbitrarily combining these are also included in the present invention.

The present invention can be used for communication devices such as a multiplexer (including a duplexer) including a plurality of filters, a multi-filter, a transmission device, a reception device, and the like.

1,

1a multiplexer

11, 12 filter 13 filter (first filter)
14 Filter (second filter)
20

Common terminal

21, 22, 23, 24 Input /

output terminal

32a, 32b, 32c, 32d, 32e Series arm resonator 34a Parallel arm resonator (second parallel arm resonator)
34b, 34c Parallel arm resonator 34d Parallel arm resonator (first parallel arm resonator)
36a Inductor (second inductor)
36b, 36c Inductor 36d Inductor (first inductor)
DESCRIPTION OF SYMBOLS 100 Surface

acoustic wave filter

101a, 101b

IDT electrode

102a,

102b Electrode finger

104a, 104b Bus bar electrode 106 Piezoelectric substrate 107 Adhesion layer 108 Main electrode layer 109 Protective layer

Claims

A first filter that passes high frequency signals;
A second filter composed of a ladder filter that allows a high-frequency signal in a frequency band higher than that of the first filter to pass therethrough,
The second filter is:
At least one series arm resonator connected in series between a common terminal to which the first filter and the second filter are connected, and an input / output terminal opposite to the common terminal;
A plurality of parallel arm resonators connected between a node to which the series arm resonator is connected and a ground;
Of the plurality of parallel arm resonators, the first parallel arm resonator disposed on the side farthest from the common terminal and the second parallel arm resonator disposed on the most common terminal side, A first inductor having an inductance value larger than an inductance value between the second parallel arm resonator and the ground is connected between the first parallel arm resonator and the ground.
Multiplexer.
A second inductor having an inductance value smaller than the inductance value of the first inductor is connected between the second parallel arm resonator and the ground.
The multiplexer according to claim 1.
No inductor is connected between the second parallel arm resonator and the ground,
The multiplexer according to claim 1.
A frequency band of a high-frequency signal to pass therethrough further includes at least one other filter different from the first filter and the second filter;
The multiplexer according to any one of claims 1 to 3.
The second filter is a filter that passes a high-frequency signal in the highest frequency band among a plurality of filters provided in the multiplexer.
The multiplexer according to any one of claims 1 to 4.
The inductance value of the second inductor is 1.8 nH or less.
The multiplexer according to any one of claims 1 to 5.