Band attenuation filter, extractor, and communication device

Abstract

To provide a band attenuation filter advantageous to simplification.SOLUTION: The band attenuation filter includes a signal path that passes a signal in a pass band between a first attenuation band and a second attenuation band that do not overlap with each other. The band attenuation filter includes the first and second acoustic wave resonators and / or the fifth and sixth acoustic wave resonators corresponding to the two band attenuation filters. The first and second acoustic wave resonators connect the signal path and the reference potential portion in parallel with each other and have resonant frequencies in attenuation bands different from each other. The fifth and sixth acoustic wave resonators are connected in series with each other on a skip path that bypasses a node connected to the reference potential portion of the signal path, and have anti-resonant frequencies in attenuation bands different from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a band attenuation filter that attenuates a signal in an attenuation band, an extractor having the band attenuation filter, and a communication device having the extractor. [Background technology]

[0002] Known band elimination filters include acoustic wave resonators (see, for example, Patent Document 1 below). The band elimination filter of Patent Document 1 includes a plurality of acoustic wave resonators connected in series to form a signal path, and an inductor that connects a node between adjacent acoustic wave resonators in the signal path to a reference potential section. In Patent Document 1, the band elimination filter and a band-pass filter are connected to a common terminal to form an extractor. The attenuation band of the band elimination filter and the pass band of the band-pass filter overlap each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 105589 Summary of the Invention [Problem to be solved by the invention]

[0004] Bandpass attenuation filters, extractors and communication devices that are advantageous in terms of simplicity are desired. [Means for solving the problem]

[0005] A band attenuation filter according to one embodiment of the present disclosure includes a signal path that passes signals in a pass band between a first attenuation band and a second attenuation band that do not overlap each other, a first acoustic wave resonator that connects the signal path to a reference potential section and has a resonant frequency in the first attenuation band, and a second acoustic wave resonator that connects the signal path to the reference potential section and has a resonant frequency in the second attenuation band, in parallel with the first acoustic wave resonator.

[0006] A band attenuation filter according to one embodiment of the present disclosure includes a signal path that passes signals in a passband between a first attenuation band and a second attenuation band that do not overlap each other, one or more parallel arms that connect one or more nodes of the signal path to a reference potential section, and a jump path that branches off from the signal path so as to bypass at least one of the one or more nodes and merges with the signal path, wherein the jump path includes a fifth acoustic wave resonator that has an anti-resonance frequency in the first attenuation band, and a sixth acoustic wave resonator that has an anti-resonance frequency in the second attenuation band and is connected in series to the fifth acoustic wave resonator.

[0007] An extractor according to one embodiment of the present disclosure includes the above-mentioned band attenuation filter connecting a common terminal and a first terminal, a first band-pass filter connecting the common terminal and a second terminal and having a first pass band that at least partially overlaps with the first attenuation band, and a second band-pass filter connecting the common terminal and a third terminal and having a second pass band that at least partially overlaps with the second attenuation band and does not overlap with the first pass band.

[0008] A communication device according to one embodiment of the present disclosure includes the extractor, an antenna connected to the common terminal, and an IC connected to the common terminal via the first band-pass filter, the second band-pass filter, and the band attenuation filter, and processing at least one of a received signal from the common terminal and a transmitted signal to the common terminal. [Effects of the Invention]

[0009] According to the above configuration, for example, the configuration of the band attenuation filter can be simplified. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a circuit diagram showing the configuration of an extractor according to an embodiment. [Figure 2] FIG. 2 shows the filter characteristics of the extractor of FIG. 1. [Figure 3] 5A and 5B are diagrams illustrating the characteristics of a plurality of acoustic wave resonators included in the band elimination filter according to the embodiment. [Figure 4] FIG. 2 is a schematic perspective view illustrating inductive coupling in the band attenuation filter according to the embodiment. [Figure 5] 10A and 10B are diagrams showing the influence of a change in the coupling coefficient of inductive coupling on filter characteristics in the band attenuation filter according to the embodiment. [Figure 6] 10A and 10B are diagrams showing the influence of a change in the coupling coefficient of inductive coupling on the width of a passband in the band attenuation filter according to the embodiment. [Figure 7] 1A and 1B are diagrams showing an example of the structure of an extractor according to an embodiment. [Figure 8] FIG. 1 is a block diagram showing a main part of a communication device according to an embodiment. [Figure 9] FIG. 10 is a circuit diagram showing the configuration of an extractor according to another example. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the following description, the band attenuation filter may be abbreviated as a BE filter (BE: band elimination). The band pass filter may be abbreviated as a BP filter. In the present disclosure, the terms attenuation band and stop band are not particularly distinguished. The attenuation band may be, for example, a band pass characteristic (e.g., |S 21 |parameter) is a band where the passband characteristic is less than -3 dB (for convenience, this includes the so-called transition band). The passband is, for example, a band where the passband characteristic is -3 dB or more. Unless otherwise specified or where there is no contradiction, the term "reference potential portion" may be understood to refer to the entirety of one or more portions to which a reference potential is applied.

[0012] (Overview of band-reducing filters) 1 is a circuit diagram showing the configuration of an extractor 1 according to an embodiment. The extractor 1 has the following three signal paths: First path: from the common terminal 3A through the BP filter 5A to the BP terminal 3P1. Second path: from the common terminal 3A through the BP filter 5B to the BP terminal 3P2. Third path: From the common terminal 3A via the BE filter 7 to the BE terminal 3E. Note that the signal may flow from the common terminal 3A to each filter and / or vice versa.

[0013] 2 is a diagram showing an example of the characteristics of the extractor 1. The upper diagram shows the pass characteristic |S 31 The middle figure shows the pass characteristic |S 41 The lower graph shows the pass characteristic |S 21 |(dB). The horizontal axis represents frequency f (GHz). The vertical axis represents the pass characteristics.

[0014] The BP filter 5A passes signals in the pass band B1A. The BP filter 5B passes signals in the pass band B1B. The pass bands B1A and B1B do not overlap. The BE filter 7 attenuates signals in the attenuation bands B2A and B2B (or, conversely, passes signals in the outer pass bands B5 to B7). The attenuation band B2A corresponds to the pass band B1A (they at least partially overlap). The attenuation band B2B corresponds to the pass band B1B (they at least partially overlap).

[0015] With this configuration, for example, the common terminal 3A (and elements such as an antenna connected to the common terminal 3A) is shared by three or more passbands, including the passbands B1A and B1B and a passband different from the passbands (a passband located in any of the passbands B5 to B7). Furthermore, one BE filter 7 can accommodate two attenuation bands B2A and B2B.

[0016] 1, the BE filter 7 has, for example, resonators 17 (17A1, 17A2, 17B1, 17B2, 17C1, 17C2, 17D1, 17D2, 17E1, and 17E2). The resonators 17 are, for example, elastic wave resonators that utilize elastic waves (the same applies to the other resonators 17 described later). In other words, the BE filter 7 is an elastic wave filter.

[0017] The resonator 17 has a characteristic that, for example, the absolute value of the impedance |Z| becomes a minimum value at the resonance frequency and becomes a maximum value at the anti-resonance frequency (see the lower part of FIG. 3 described later. For convenience, |Z| may be simply referred to as impedance). In the description of the embodiment, for convenience, a case will be taken as an example in which the anti-resonance frequency is higher than the resonance frequency, unless otherwise specified. However, the high-low relationship between the two may be reversed.

[0018] The resonator 17 may be arranged in the following three positions, for example. In the following description, the signal path 11 is a path within the BE filter 7 that connects the common terminal 3A and the BE terminal 3E. The node 15 refers to the node of the signal path 11 that is connected to the reference potential unit 13. Parallel arm 23: A path branching from the signal path 11 and connecting the node 15 to the reference potential section 13. Series arm 21: A portion of the signal path 11 that is separated by adjacent nodes 15 (connected to the reference potential section 13). Jump path 24: A path that branches off from the signal path 11 to bypass (jump over) at least one node 15 and then joins the signal path 11.

[0019] Just to be clear, parts that can be considered to be substantially the same from an electrical point of view may be considered as one node.

[0020] 1 may be wired in the actual structure. Unlike the illustrated example, if the end of signal path 11 on the common terminal 3A side or the BE terminal 3E side is connected to reference potential unit 13, node 15 may be considered to be located at that end (the series arm 21 is not located there, and the parallel arm 23 is connected).

[0021] Furthermore, for example, the jump path 24 and the inductor 19B (described later) are connected to the same node 15 (15B), but from a three-dimensional spatial perspective, rather than an electrical perspective, their connection positions to the signal path 11 may be separated from each other. In Fig. 1, the node 15 (15C) to which the parallel resonators 17E1 and 17E2 are connected is shown by two points, but these two points may be considered to represent the same node 15C.

[0022] Furthermore, for example, when the jump path 24 bypasses one node 15 (15B), at least two electronic elements (four resonators 17 in the illustrated example) located on both sides of the bypassed node 15 in the signal path 11 are also bypassed. Examples of such electronic elements include the resonators 17, as well as inductors, capacitors, and LC resonant circuits (resonators that do not utilize acoustic waves from another perspective; the same applies hereinafter).

[0023] 1, as indicated by the presence or absence of hatching, two types of resonators 17, namely, a resonator 17 corresponding to the attenuation band B2A and a resonator 17 corresponding to the attenuation band B2B, are positioned at each of the three arrangement positions of the resonators 17. This makes it possible to realize or improve a filter characteristic having two attenuation bands B2B, for example.

[0024] For example, two parallel resonators 17E1 and 17E2 are connected to the node 15C. These may be considered to be included in one parallel arm 23 and connected in parallel to each other. The resonant frequency of the parallel resonator 17E1 is located in the attenuation band B2A, thereby forming, for example, an attenuation pole in the attenuation band B2A. The resonant frequency of the parallel resonator 17E2 is located in the attenuation band B2B, thereby forming, for example, an attenuation pole in the attenuation band B2B.

[0025] Furthermore, for example, at least one (three (plural) in the illustrated example) of one or more (four (plural) in the illustrated example) series arms 21 has two resonators 17 connected in series to each other. For example, taking the series arm 21 between nodes 15A and 15B as an example, the series arm 21 has two series resonators 17B1 and 17B2. The anti-resonant frequency of the series resonator 17B1 is located in the attenuation band B2A, thereby forming, for example, an attenuation pole in the attenuation band B2A. The anti-resonant frequency of the series resonator 17B2 is located in the attenuation band B2B, thereby forming, for example, an attenuation pole in the attenuation band B2B.

[0026] Furthermore, for example, each of one or more (one in the illustrated example) skip paths 24 has two skip resonators 17D1 and 17D2 connected in series to each other. The anti-resonance frequency of the skip resonator 17D1 is located in the attenuation band B2A. The anti-resonance frequency of the skip resonator 17D2 is located in the attenuation band B2B. This allows the pass characteristics of the pass bands B5 to B7 to be improved without degrading the attenuation characteristics of the BE filter 7 in the attenuation bands B2A and B2B, as will be described later.

[0027] Note that technical matters may be extracted from the embodiments from various viewpoints different from those described above. In this case, unlike the above description, for example, the BE filter 7 does not need to have two types of resonators 17 corresponding to the two attenuation bands.

[0028] The above is an outline of the embodiment. The following will provide an outline of the embodiment, in the following order: 1. Extractors in general (Figures 1 and 2) 2.BE filter 2.1.BE Filters in General (Figures 1 and 9) 2.2. Series resonator (Figs. 1 and 3) 2.3. Parallel resonator (Figs. 1 and 3) 2.4. Jump Path (Jump Resonator) (Figures 1 and 3) 2.5. Inductors (Figs. 4 to 6) 2.5.1.Inductor Configuration 2.5.2.Effect of Inductive Coupling on Filter Characteristics 3. Example of extractor structure (Figure 7) 4. Example of communication device (Figure 8) 5. Summary of embodiments

[0029] (1. Extractors in general) In the following description, for convenience, the BP filters 5A and 5B will not be distinguished from each other and may be referred to as the BP filter 5 (reference numerals shown in FIG. 7, etc.). The BP terminals 3P1 and 3P2 will not be distinguished from each other and may be referred to as the BP terminal 3P (reference numerals shown in FIG. 7, etc.). The attenuation bands B2A and B2B will not be distinguished from each other and may be referred to as the attenuation band B2 (reference numerals shown in FIG. 3).

[0030] Furthermore, the two types of resonators 17 corresponding to the attenuation bands B2A and B2B may be referred to using the same reference numerals without distinction. Specifically, the reference numerals on the left (shown in FIG. 7, etc.) may be used instead of the reference numerals on the right below. 17A: 17A1 / 17A2 17B: 17B1 / 17B2 17C: 17C1 / 17C2 17D: 17D1 / 17D2 17E: 17E1 / 17E2

[0031] 1 has, for example, three filters (5A, 5B, and 7) connected to a common terminal 3A, as described above. A matching circuit 9 for impedance matching may be interposed between the common terminal 3A and these filters.

[0032] Unlike the illustrated example, the extractor 1 may have only one of the BP filters 5A and 5B (the other may be external). Conversely, the extractor 1 may have three or more BP filters 5, and the BE filter 7 may have three or more attenuation bands B2. A duplexer may be interposed between the two BP filters 5 and the common terminal 3A.

[0033] The specific configuration of the BP filter 5 is arbitrary. For example, the BP filter 5 may be an acoustic wave filter that uses acoustic waves and / or a filter including an LC circuit. In the illustrated example, the BP filter 5 is a ladder-type filter having multiple resonators 17 (17S and 17P) connected in a ladder configuration.

[0034] As described above, in the embodiment, the resonator 17 is an acoustic wave resonator, and the BP filter 5 is an acoustic wave filter. Other acoustic wave filters include, for example, a multi-mode (including dual-mode) filter in which IDT (Interdigital Transducer) electrodes (not shown) of the resonator 17 are arranged in the propagation direction of acoustic waves.

[0035] In the illustrated example, more specifically, the BP filter 5 has a plurality of (five in the illustrated example) series resonators 17S connected in series with each other between the common terminal 3A and the BP terminal 3P to form a signal path (reference symbols omitted), and a plurality of (five in the illustrated example) parallel resonators 17P connecting a plurality of nodes (reference symbols omitted) in the signal path to the reference potential section 13.

[0036] The multiple series resonators 17S have substantially the same resonant frequencies and substantially the same anti-resonant frequencies. The same is true for the multiple parallel resonators 17P. The anti-resonant frequencies of the parallel resonators 17P and the series resonators 17S are substantially the same. This achieves filter characteristics with a passband B1A or B1B that is slightly narrower than the range from the resonant frequency of the parallel resonators 17P to the anti-resonant frequency of the series resonators 17S.

[0037] Unlike the illustrated example, the number of series resonators 17S (series arms from another perspective) may be one. Similarly, the number of parallel resonators 17P (parallel arms from another perspective) may be one. Also, various known modifications may be made. For example, other electronic elements may be provided in addition to or instead of the resonator 17. Examples of other electronic elements include inductors, capacitors, and LC resonant circuits. In the illustrated example, inductors are provided at various positions, although their reference numerals are omitted.

[0038] Two or more (two in the illustrated example) BP filters 5 (5A and 5B) whose passbands do not overlap each other may have the same configuration (except for specific design values ​​for different passbands) or different configurations. For example, as in the example of FIG. 1, both filters may be ladder-type acoustic wave filters with the same number of stages, or may be acoustic wave filters with different numbers of stages or types (e.g., ladder type and multimode type), or may be filters of different types, whether they are acoustic wave filters or not.

[0039] The specific configuration of the matching circuit 9 is arbitrary. In the illustrated example, a configuration including an inductor is illustrated, although no particular reference numeral is given to it. Although not particularly illustrated, the matching circuit 9 may include, for example, other electronic elements in addition to or instead of the inductor. Examples of other electronic elements include a capacitor and a resistor.

[0040] As described above, the resonator 17 included in each filter (5A, 5B, or 7) may be an acoustic wave resonator. The type of acoustic wave is arbitrary. For example, the acoustic wave may be a surface acoustic wave (SAW), a bulk acoustic wave (BAW), a plate wave, or a boundary acoustic wave. The acoustic wave may propagate along the surface of a piezoelectric body (not shown), or may propagate in the normal direction to the surface of the piezoelectric body. One resonator 17 may be configured by connecting multiple split resonators having approximately the same characteristics in series or in parallel.

[0041] The passband B1A and the attenuation band B2A overlap at least partially in their bandwidths. This portion may be, for example, 50% or more or 70% or more of the bandwidth. The same applies to the passband B1B and the attenuation band B2B. The frequencies and widths of the passbands B1A and B1B (attenuation bands B2A and B2B) and the passbands B5 to B7 are arbitrary. In the illustrated example, these bands have relatively high frequencies. For example, the passbands B1A and B1B (attenuation bands B2A and B2B) are located in the range of 1 GHz to 3 GHz.

[0042] Although not particularly shown, the characteristics of the BE filter 7 may not have the pass bands B5 and / or B7. For example, the characteristics of the BE filter 7 may be such that the attenuation band B2A is adjacent to the low frequency side of the pass band of a high-pass filter, or such that the attenuation band B2B is adjacent to the high frequency side of the pass band of a low-pass filter.

[0043] (2.BE filter) (2.1.BE filters in general) 1 has one or more (four in the illustrated example) series arms 21, one or more (three in the illustrated example) parallel arms 23, and one or more (one in the illustrated example) jump paths 24. The jump paths 24 do not necessarily have to be provided.

[0044] In the signal path 11, a series arm 21 may be located closest to the common terminal 3A and closest to the BE terminal 3E (in the illustrated example), or a parallel arm 23 may be connected. The parallel arms 23 connected to different nodes 15 may join together on the reference potential unit 13 side, or may share some electronic elements (see the two parallel resonators 17P on the BP terminal 3P side of the BP filter 5).

[0045] Each of the one or more series arms 21 has one or more electronic elements. Examples of such electronic elements include resonators 17 (see the three series arms 21 on the left side in FIG. 1), inductors (see the one series arm 21 on the right side in FIG. 1), capacitors (not shown), and LC resonant circuits (not shown). When one series arm 21 has two or more electronic elements, the two or more electronic elements may be connected in series or in parallel.

[0046] The number of series arms 21 is arbitrary, and as described above, the series arms 21 may include any electronic elements. Therefore, unlike the illustrated example, all of the series arms 21 may include resonators 17, or none of the series arms 21 may include resonators 17. An example of the latter is a mode in which all of the series arms 21 include inductors.

[0047] In the illustrated example, the series arm 21 closest to the BE terminal 3E has an inductor (reference numeral omitted) instead of the resonator 17. This inductor may be used to define the characteristics of the high frequency side of the pass band B7, which is located on the higher frequency side than the attenuation bands B2A and B2B, or may be used for impedance matching.

[0048] Each of the one or more parallel arms 23 has one or more electronic elements. Examples of such electronic elements include a resonator 17 (see one parallel arm 23 on the right side in FIG. 1), an inductor 19 (see two parallel arms 23 on the left side in FIG. 1), a capacitor (not shown), and an LC resonant circuit (not shown). When one parallel arm 23 has two or more electronic elements, the two or more electronic elements may be connected in series or in parallel.

[0049] The number of parallel arms 23 is arbitrary, and as described above, the parallel arms 23 may include any electronic elements. Therefore, unlike the example of Fig. 1, all of the parallel arms 23 may include the resonators 17 (see Fig. 9), or none of the parallel arms 23 may include the resonators 17. An example of the latter embodiment is one in which all of the parallel arms 23 include the inductors 19.

[0050] In the embodiment, as described above, two types of resonators 17 corresponding to two attenuation bands B2A and B2B are located at any of the arrangement positions of the resonators 17 (series arm 21, parallel arm 23, and jump path 24). When two types of resonators 17 are connected in series, the relationship between the frequencies of the two resonators 17 and the connection order is arbitrary. The connection order of the two types of resonators 17 may be different between multiple series arms 21.

[0051] 1 can be modified in various ways. For example, two types of resonators 17 may be provided only in the series arms 21 without providing the jump paths 24, or two types of resonators 17 may be provided only in the parallel arms 23. Two types of resonators (one type of resonator 17 in each series arm 21) may be provided in two series arms 21 (similar to the parallel arms 23). Series arms 21 having one type of resonator 17 and series arms 21 having two types of resonators 17 may be mixed (similar to the parallel arms 23). One or both of the two types of resonators 17 may be replaced with other electronic elements (e.g., an LC resonant circuit).

[0052] Alternatively, for example, only two types of resonators 17 may be provided in the jump path 24. From another perspective, for example, the series arm 21 and / or the parallel arm 23 may correspond to the two attenuation bands B2 by a configuration other than the configuration having two types of resonators 17. Alternatively, for example, the resonator 17 corresponding to one of the two attenuation bands B2 may be provided only in the series arm 21 of the series arm 21 and the parallel arm 23 (not in any of the parallel arms 23), and the resonator 17 corresponding to the other of the two attenuation bands B2 may be provided only in the parallel arm 23 of the series arm 21 and the parallel arm 23 (not in any of the series arms 21).

[0053] 9 is a diagram showing an extractor 1B including a BE filter 7B according to another example, and corresponds to FIG. 1. In this example, two or more (three in the illustrated example; all from another perspective) of the multiple parallel arms 23 each have parallel resonators 17E1 and 17E2. Note that in the description of the embodiment, the extractor 1 illustrated in FIG. 1 will basically be used as an example, and the extractor 1B illustrated in FIG. 9 will also be mentioned as necessary.

[0054] (2.2. Series resonator) 3 is a diagram illustrating an example of the characteristics of the resonators 17 of the BE filter 7. For convenience, attention is focused here on the configurations corresponding to the attenuation bands B2A and B2B, respectively (the configurations relating to one attenuation band B2). The description with reference to FIG. 3 may also be applied to the series resonators 17A to 17C corresponding to the attenuation bands B2A and B2B, respectively. The same applies to the description of the parallel resonator 17E and the skip path 24 (skip resonator 17D) described later.

[0055] The upper part of Figure 3 is an enlarged view of the portion of the lower part of Figure 2 that relates to the attenuation band B2. The lower part of Figure 3 shows the characteristics of the resonator 17 of the BE filter 7. The horizontal axis of the lower part is the same as the horizontal axis of the upper part of the figure. The vertical axis of the lower part of the figure is the absolute value of the impedance |Z| (Ω). The symbols in the legend indicate the symbols of the resonator 17.

[0056] The anti-resonant frequencies faA to faC (frequencies at which |Z| is a maximum value) of the multiple series resonators 17A to 17C are, for example, slightly different from one another and located within the attenuation band B2, and form multiple attenuation poles within the attenuation band B2 independently and / or by influencing one another. Unlike the illustrated example, the multiple anti-resonant frequencies faA to faC may be the same as one another. The resonant frequencies (frequencies at which |Z| is a minimum value) of the series resonators 17A to 17C may be located within or outside the attenuation band B2.

[0057] The specific positions of the anti-resonance frequencies faA to faC within the attenuation band B2 are arbitrary. For example, when the attenuation band B2 is divided into thirds, each of the anti-resonance frequencies faA to faC may be located in any of the low-frequency range, the central range, and the high-frequency range. In the illustrated example, each of the anti-resonance frequencies faA to faC is located in the central range or the high-frequency range.

[0058] (2.3.Parallel resonator) As shown in FIG. 3 and as described above, the resonant frequency frE of the parallel resonator 17E is located, for example, in the attenuation band B2. The specific value of the resonant frequency frE is arbitrary. For example, the resonant frequency frE may be located on the lower frequency side with respect to some or all of one or more anti-resonant frequencies faA to faC (as in the illustrated example), or may be located in another range. Furthermore, the resonant frequency frE may be located in a range on the lower frequency side when the attenuation band is divided into two or three equal parts (as in the illustrated example), or may be located in another range. The resonant frequency frE may be lower than, equal to, or higher than the resonant frequencies (symbols omitted) of some or all of the series resonators 17A to 17C.

[0059] When one or more resonant frequencies frE are made lower than one or more antiresonant frequencies faA to faC, the difference therebetween may be any value. For example, when focusing on a specific parallel resonator 17E and a specific series resonator (any of 17A to 17C), the difference therebetween may be 0.2 times or more, 0.5 times or more, or 1.0 times or more the Δf (difference between the resonant frequency and the antiresonant frequency) of the specific parallel resonator 17E and / or the Δf of the specific series resonator. This difference may be established for some or all of the one or more parallel resonators 17E and one or more series resonators.

[0060] The anti-resonant frequency (symbol omitted) of the parallel resonator 17E is arbitrary and may be located within the attenuation band B2 (in the illustrated example) or may be located on the higher frequency side than the attenuation band B2. Furthermore, |Z| of the parallel resonator 17E is also arbitrary and may be smaller, equal to, or larger than the maximum or minimum values ​​of |Z| of all or some of the series resonators 17A to 17C (in the illustrated example). When multiple parallel resonators 17E are provided, the multiple resonant frequencies frE may be slightly different from each other and located within the attenuation band B2, or may be the same as each other.

[0061] In the BE filter 7 having a plurality of parallel arms 23, the parallel resonator 17E may be provided in any of the parallel arms 23. For example, the parallel resonator 17E may be included in the parallel arm 23 closest to the common terminal 3A among the plurality of parallel arms 23, or may be included in the second or subsequent parallel arm 23 from the common terminal 3A (as in the illustrated example). In other words, the first parallel arm 23 from the common terminal 3A may be configured not to include a resonator 17 (for example, an inductor 19). In the example of FIG. 1 , the parallel resonator 17E is farther from the common terminal 3A than the inductors 19A and 19B, and from another perspective, it is located in the parallel arm 23 farthest from the common terminal 3A among all the parallel arms 23.

[0062] The parallel resonator 17E, for example, exhibits a large change in impedance relative to a change in frequency. By separating such a parallel resonator 17E from the common terminal 3A, for example, impedance matching on the common terminal 3A side is facilitated. The common terminal 3A side is the side where the BP filter 5 and the BE filter 7 are coupled, and therefore the side on which it is difficult to achieve impedance matching in the extractor 1. By facilitating impedance matching on the common terminal 3A side, impedance matching is also facilitated for the entire extractor 1. However, a similar effect may be obtained on the BE terminal 3E side in addition to or instead of the common terminal 3A side.

[0063] (2.4. Jump Path (Jump Resonator)) As described above, the jump path 24 (jump resonator 17D) shown in FIG. 1 bypasses at least one node 15 and two electronic elements located on either side of the node 15. In other words, the jump path 24 is connected in parallel to at least two electronic elements sandwiching one node 15. At least one of the two electronic elements may be a resonator 17. In the example of FIG. 1, the jump path 24 is connected in parallel to four series resonators 17A1, 17A2, 17B1, and 17B2 sandwiching the node 15A. Unlike the example shown in the figure, the jump path 24 may bypass two or more nodes 15.

[0064] By providing the skip path 24, for example, a path through which signals in the pass bands B5 to B7 flow is formed in parallel with the signal path 11. This improves the pass characteristics in the pass bands B5 to B7. Because the skip path 24 is connected in parallel to two electronic elements (series resonators 17A and 17B), the likelihood of a decrease in the combined impedance of the skip path 24 and the signal path 11 in the attenuation band B2 can be reduced compared to an embodiment in which a path connected in parallel to one electronic element (17A or 17B) is provided (this embodiment is also included in the technology according to the present disclosure). In other words, it is easier to maintain the attenuation characteristics in the attenuation band B2.

[0065] The jump path 24 may be connected to any node of the signal path 11 (not necessarily the node 15 connected to the reference potential unit 13) as long as it bypasses one or more nodes 15. For example, one end and / or the other end of the jump path 24 may or may not be located at an end of the signal path 11. Also, for example, unlike the illustrated example, in a case where one series arm 21 has a resonator 17 and an inductor connected in series to each other, one end of the jump path 24 may be connected to a node between them (not connected to the reference potential unit).

[0066] 1, the node 15 skipped by the skip path 24 is a node 15 (15A) to which one of two inductors 19 (19A in the illustrated example) that are inductively coupled to each other is connected, as will be described later. One end of the skip path 24 is connected to a node 15 (15B) to which the other of two inductors 19 (19B in the illustrated example) that are inductively coupled to each other is connected. Note that the one end may be connected to a node 15C (a node 15 located on the opposite side of node 15A with respect to node 15B) instead of node 15B. The skip path 24 is connected in parallel to a path that is substantially formed by inductive coupling.

[0067] The jump path 24 may include any one or more electronic elements. In the example of FIG. 1, the jump path 24 includes the resonator 17 (jump resonators 17D (17D1, 17D2)). The jump path 24 may include other electronic elements instead of or in addition to the resonator 17. Examples of other electronic elements include a capacitor, an inductor, and an LC resonant circuit. When the jump path 24 includes two or more electronic elements (including the jump resonator 17D), the two or more electronic elements may be connected in series or in parallel.

[0068] The specific characteristics of the jump resonator 17D may be set appropriately, for example, as follows.

[0069] 3, |Z| of the skipped resonator 17D is set to be relatively large in the attenuation band B2. For example, |Z| of the skipped resonator 17D is larger than the absolute value |Z| of the combined impedance of the series resonators 17A and 17B connected in parallel to the skipped resonator 17D over the entire attenuation band B2. Also, for example, |Z| of the skipped resonator 17D is larger than the |Z| of any of the series resonators 17A to 17C over the entire attenuation band B2. The degree of difference in magnitude is arbitrary. Also, outside the attenuation band B2, |Z| of the skipped resonator 17D is arbitrary.

[0070] The |Z| of the resonator 17 can be adjusted by, for example, the capacitance of the excitation electrode (e.g., IDT electrode) of the resonator 17. Therefore, for example, in the above description, the term |Z| may be replaced with the term capacitance. The magnitude relationships exemplified above regarding the |Z| or capacitance of the resonator 17 may hold when, for example, focusing on one attenuation band B2 (B2A or B2B) and the resonator 17 associated with that one attenuation band B2.

[0071] As described above, the signal path 11 and the skip path 24 may include electronic elements other than the resonator 17. Taking such an embodiment into consideration, in the above description, the combination of the series resonators 17A and 17B may be rephrased as the portion of the signal path 11 that is bypassed by the skip path 24. Each of the series resonators 17A to 17C may be rephrased as a series arm 21. The skip resonator 17D may be rephrased as the skip path 24. In such a case, the magnitude relationship regarding |Z| described above may hold for, for example, the entire two or more attenuation bands B2 (B2A and B2B).

[0072] The anti-resonance frequency faD of the skip resonator 17D is located within the attenuation band B2. Its specific value is arbitrary. For example, the anti-resonance frequency faD may be located in a range between the lowest (faB) and highest (faA) anti-resonance frequencies of all the series resonators (as in the illustrated example), or may be located outside the above range. Furthermore, when the attenuation band B2 is divided into two equal parts, the anti-resonance frequency faD may be located on the low-frequency side or on the high-frequency side (as in the illustrated example). When the attenuation band B2 is divided into three equal parts, the anti-resonance frequency of the skip resonator 17D may be located in the middle range (as in the illustrated example), or in the low-frequency or high-frequency range.

[0073] The jump path 24 having the jump resonator 17D can reduce degradation of characteristics within the attenuation band B2 compared to, for example, an embodiment in which a capacitor is provided instead of the jump resonator 17D (this embodiment may also be included in the technology according to the present disclosure). Specifically, for example, characteristics are improved at and around the anti-resonance frequency faD. This is because, for example, while the impedance of a capacitor decreases as the frequency increases, the jump resonator 17D can increase impedance at and around the anti-resonance frequency.

[0074] (2.5. Inductors) (2.5.1. Inductor Structure) 1, one or more (two in the illustrated example) parallel arms 23 have inductors 19 (19A or 19B). The inductor 19 is set, for example, so that its cutoff frequency is located on the lower frequency side of the pass band B5, which is the lowest frequency of the pass bands B5 to B7, and contributes to forming a slope on the lower frequency side of the pass band B5. However, the cutoff frequency of the inductor 19 may be set lower than the above.

[0075] In the example of FIG. 1, two or more (two in the illustrated example) parallel arms 23 have inductors 19 (19A and 19B). The two or more (two) inductors 19A and 19B are inductively coupled to each other. This allows the width of the pass bands B5 to B7 to be adjusted, as will be described in detail later. For example, the width of the pass bands B5 to B7 can be widened by reducing the coupling coefficient between them, or even by setting the coupling coefficient to a negative value (differentially coupling them).

[0076] 1, the matching circuit 9 has an inductor (reference numeral omitted) connected to the reference potential section 13. On the other hand, two inductors 19A and 19B that are inductively coupled to each other are included in the BE filter 7, for example, and are not included in the matching circuit 9. From another perspective, the two inductors 19 contribute to defining the filter characteristics of the BE filter 7, and do not contribute (only) to impedance matching. The fact that the inductor 19 is not an inductor of the matching circuit 9 may be reasonably determined from various perspectives.

[0077] For example, if the inductor 19 is not connected to the end of the signal path 11 (for example, if the resonator 17 is located outside the node 15 to which the inductor 19 is connected), the inductor 19 is not part of the matching circuit 9. Also, even if the inductor 19 is connected to the end of the signal path 11, if a matching circuit 9 that is structurally added later is connected outside the inductor 19 via a terminal, the inductor 19 is not part of the matching circuit 9.

[0078] Furthermore, since an inductor used only for impedance matching does not normally define the slope on the low-frequency side of the pass band B5 by a cutoff frequency, it can be determined from this viewpoint whether it is an inductor for matching circuit 9. Also, related to the above, the inductance of the inductor (connected to the reference potential) for matching circuit 9 is normally sufficiently large compared to the inductance of inductor 19, so it can be determined from this viewpoint.

[0079] The inductor 19 included in the BE filter 7 may contribute to impedance matching in addition to, or instead of, defining the filter characteristics. The inductor of the matching circuit 9 may also be used for inductive coupling. While the inductor 19 in the parallel arm 23 has been described as being different from the inductor in the matching circuit 9 (connected to the reference potential unit 13), the inductor in the series arm 21 and / or other electronic elements (capacitors, etc.) may also be distinguished between those in the matching circuit 9 and those in the BE filter 7 using the same or similar concept.

[0080] When a jump path 24 is provided, the parallel arm 23 connected to the node 15 (15A in the illustrated example) jumped by the jump path 24 may include an inductor 19 (19A in the illustrated example). The inductance of this inductor 19 (19A) may (or may not) be larger than, for example, the inductance of the inductor 19 (19B in the illustrated example) connected to the node 15 (15B in the illustrated example) that is not jumped by the jump path 24. The specific degree of difference is arbitrary. For example, the inductance of the inductor 19A may be 1.1 times or more, 1.5 times or more, or 2.0 times or more the inductance of the inductor 19B.

[0081] As described above, at least two of the inductors 19 included in the two or more parallel arms 23 are inductively coupled to each other. When three or more parallel arms 23 include inductors 19, the number of inductors 19 inductively coupled to each other may be all or some, or may be two, or may be three or more. When three or more inductors 19 are inductively coupled, the inductors may be inductively coupled in that order, for example, the first inductor and the second inductor are inductively coupled, the second inductor and the third inductor are inductively coupled, and the third inductor and the first inductor are not inductively coupled, or each inductor may be inductively coupled to all the other inductors.

[0082] The inductive coupling may be summation coupling or differential coupling. When three or more inductors 19 are inductively coupled, only summation coupling, only differential coupling, or a combination of both may be employed. The definitions of summation coupling and differential coupling for the inductors 19 of the two parallel arms 23 will be described below in the description of examples of the arrangement of the inductors 19.

[0083] FIG. 4 shows an example of an arrangement of two inductors 19 that are differentially coupled to each other.

[0084] In the example shown in the upper part of FIG. 4, two inductors 19 are arranged in series. In this example, the end of each of the two inductors 19 located at the bottom of the figure is connected to the reference potential section 13. The end located at the top of the figure is connected to the signal path 11. However, the two inductors 19 have opposite directions of rotation when tracing the conductor from the signal path 11 to the reference potential section 13. Therefore, when a signal flows from the signal path 11 to the reference potential section 13 through the two inductors 19, the magnetic fields formed by the two inductors 19 on the sides of their central axes have opposite directions. Consequently, the magnetic fields of both inductors weaken each other.

[0085] Thus, differential coupling in the inductors 19 of two or more parallel arms 23 refers to coupling in which the magnetic fields formed by the two inductors 19 weaken each other (the degree of weakening is greater than the degree of constructive coupling) when a signal flows in parallel from the signal path 11 to the reference potential section 13 via two or more inductors 19. Conversely, constructive coupling is coupling in which the magnetic fields strengthen each other.

[0086] In the example in the middle of Figure 4, two inductors 19 are arranged in parallel. In this example, as in the example in the top, a signal flows from the end located at the top of the figure through the two inductors 19 to the end located at the bottom of the figure. Meanwhile, the two inductors 19 have the same direction of rotation when tracing the conductor from the signal path 11 to the reference potential section 13. Therefore, when a signal flows from the signal path 11 to the reference potential section 13 through the two inductors 19, the direction of the magnetic field formed by one inductor 19 inside the other inductor 19 is opposite to the direction of the magnetic field formed by the other inductor 19 itself. Consequently, the magnetic fields of both inductors weaken each other.

[0087] In the example shown in the lower part of FIG. 4, the two inductors 19 overlap at least part of their three-dimensional arrangement range (space). In other words, the two inductors 19 are interdigitated with each other. In this example, as in the other examples described above, a signal flows from the end located at the top of the figure to the end located at the bottom of the figure via the two inductors 19. Meanwhile, the two inductors 19 have opposite directions of rotation when tracing the conductor from the signal path 11 to the reference potential section 13. Therefore, when a signal flows from the signal path 11 to the reference potential section 13 via the two inductors 19, the magnetic fields they generate are opposite to each other, and the two magnetic fields weaken each other.

[0088] The above explanation of the example in the lower part of Figure 4 is based on the premise that the arrangement ranges (in other words, the inner ranges) of the two inductors 19 overlap with each other over a large portion (for example, 60% or more, 70% or more, or 100% of the volume of the inner region). However, the two inductors 19 may overlap with each other by an amount that does not satisfy the above explanation. Instead of two inductors 19, three or more inductors 19 may be interdigitated.

[0089] 4, the two inductors 19 may strengthen the magnetic field in some areas and weaken the magnetic field in other areas, as can be understood by considering the case where the arrangement ranges of the two inductors 19 are offset from each other. In such a case, whether the coupling is additive or differential may be determined based on, for example, the positive or negative of the coupling coefficient obtained by back-calculating from the electrical characteristics.

[0090] The inductor 19 may be arranged in various ways to achieve differential or additive coupling other than the illustrated example.

[0091] For example, unlike the upper part of Figure 4, inductors 19 having the same rotation direction may be arranged in series, and the upper end of one inductor 19 may be connected to the reference potential section 13 and the lower end may be connected to the signal path 11, thereby realizing differential coupling.

[0092] Also, for example, unlike the middle section of Figure 4, inductors 19 with opposite winding directions may be arranged in parallel, and the upper end of one of the inductors 19 may be connected to the reference potential section 13 and the lower end may be connected to the signal path 11, thereby realizing differential coupling.

[0093] 4, for example, inductors 19 having the same spiral direction may be arranged in a double spiral, and the upper end of one of the inductors 19 may be connected to the reference potential section 13 and the lower end may be connected to the signal path 11, thereby realizing differential coupling. Three or more inductors 19 may be arranged in a multiple spiral.

[0094] Furthermore, for example, although not particularly shown, one inductor 19 may be positioned concentrically inside the other inductor 19. At least one inductor 19 may not be three-dimensional but may be planar (for example, spiral).

[0095] The structure of inductor 19 may be various. For example, although not shown, inductor 19 may be configured by a conductor pattern (layered conductor) and vias provided on a multilayer substrate. In this case, the axial direction of inductor 19 may be the stacking direction of the multilayer substrate or may be a direction along the layers of the multilayer substrate.

[0096] When two inductors 19 are spaced apart, whether the inductors 19 are inductively coupled may be reasonably determined based on the filter characteristics of the BE filter 7. For example, as will be shown later, a difference of 0.05 in the coupling coefficient indicates a significant difference in the filter characteristics. Therefore, for example, when the absolute value of the coupling coefficient is 0.03 or greater or 0.05 or greater, it may be determined that the two inductors 19 are inductively coupled.

[0097] (2.5.2. Effect of inductive coupling on filter characteristics) FIG. 5, like the lower part of FIG. 2, shows the pass characteristics of the BE filter 7. The lower part of FIG. 5 is a partially enlarged view of the upper part of FIG. 5. The multiple lines in the figure represent different coupling coefficients for inductors 19A and 19B. As shown in the legend, the coupling coefficient k varies in increments of 0.05 within the range of −0.30 to +0.30. A negative sign indicates differential coupling, and a positive sign indicates additive coupling. The illustrated filter characteristics were obtained by simulation calculation.

[0098] 5 also shows a line where the transmission characteristic is −3 dB. As described above, in the description of the embodiment, the transmission characteristic |S 21 The frequency band where | is -3 dB or more is treated as the pass band B5 to B7. As shown in this figure, the change in the coupling coefficient 21 The frequency at which | is -3dB varies.

[0099] Figure 6 shows the coupling coefficient and |S 21 6 is a diagram showing the relationship between the coupling coefficient k and the frequency at which | is -3 dB. In this diagram, the horizontal axis represents the coupling coefficient k. The vertical axis represents the frequency f (GHz). The plots and lines in the diagram represent the lower limit LL and upper limit LH of the pass band B5, the lower limit ML and upper limit MH of the pass band B6, and the lower limit HL and upper limit HH of the pass band B7, as shown in the legend and the diagram in the upper right (schematic representation of the lower part of FIG. 2). FIG. 6 was obtained based on FIG. 5.

[0100] 6 (and FIG. 5), in each of the passbands B5 to B7, the smaller the coupling coefficient, the wider the bandwidth. In the illustrated example, when the coupling coefficient is 0 or greater, |Z| on the lower frequency side than the attenuation band B2A becomes smaller than −3 dB, and as a result, the passband B5 is not ensured.

[0101] In this way, the width, lower limit, and / or upper limit of the attenuation band B2 and / or the pass bands B5 to B7 can be adjusted by inductive coupling. For example, from the viewpoint of widening the pass bands B5 to B7, the coupling coefficient may be set to 0.05 or less (but not including 0), or even a negative value.

[0102] The reason why the width of the passbands B5 to B7 becomes wider as the coupling coefficient becomes smaller is, for example, that a path that is essentially connected in parallel to the signal path 11 by inductive coupling is formed, and the smaller the coupling coefficient, the easier it is for a signal to flow through this path. Based on this effect, it is possible to obtain a qualitative effect of adjusting (e.g., widening) the bandwidth by changing the coupling coefficient, regardless of the specific arrangement and design values ​​of the resonator 17, the inductor 19, etc.

[0103] The coupling coefficient may be adjusted by various methods, for example, by adjusting the distance between two inductors 19 that are separated from each other, or by adjusting the amount of overlap between inductors 19 that overlap each other.

[0104] (3. Example of extractor structure) FIG. 7 is a schematic exploded perspective view showing an example of the structure of the extractor 1. However, for convenience of explanation, the configuration for the extractor 1 to accommodate two passbands B1A and B1B (two attenuation bands B2) is omitted. Specifically, FIG. 7 shows only one BP filter 5. Only one resonator 17 is shown in the series arm 21, the parallel arm 23, and the jump path 24. Furthermore, for convenience of illustration, the number of resonators 17 in the BP filter 5 is reduced compared to FIG. 1.

[0105] The extractor 1 includes, for example, a multilayer substrate 31 and an acoustic wave chip 33 mounted on the multilayer substrate 31.

[0106] The multilayer substrate 31, for example, has an insulating substrate and conductors located inside or on the surface thereof, although no particular reference numeral is given to these. The conductors include, for example, conductor patterns (layered conductors) and vias that connect the layered conductor patterns to each other. The conductor patterns and vias constitute, for example, inductors (e.g., inductor 19), capacitors, and terminals (e.g., 3A, 3P, and 3E, as well as those for the reference potential) that the extractor 1 has.

[0107] The acoustic wave chip 33 has, for example, a substrate (reference numeral omitted) having at least a portion of one surface formed of a piezoelectric element 33a. The substrate may be formed entirely of the piezoelectric element 33a, may be formed by laminating multiple layers including the piezoelectric element 33a, or may have a cavity overlapping the piezoelectric element 33a. An IDT electrode 33b is positioned on the piezoelectric element 33a, thereby forming a resonator 17. In FIG. 7, the IDT electrode 33b is schematically represented by a symbol of two interlocking prongs.

[0108] 7, the resonators 17 (e.g., all of them) of the BP filter 5 (both or one of 5A and 5B) and the resonators 17 (e.g., all of them) of the BE filter 7 may be located on the same piezoelectric body 33a. Furthermore, the resonators 17 of the BP filter 5 and the resonators 17 of the BE filter 7 may be made of the same material (e.g., lithium tantalate or lithium niobate), have the same cut angle, and have the same thickness as the piezoelectric body 33a (piezoelectric layer). Furthermore, the thickness of the IDT electrode 33b (excitation electrode) may be the same for the resonators 17 of the BP filter 5 (both or one of 5A and 5B) and the resonators 17 of the BE filter 7.

[0109] Unlike the above description, for example, the BP filter 5 (5A and / or 5B) and the BE filter 7 may be provided on separate acoustic wave chips and mounted on the same multilayer substrate. Furthermore, some, all, or all of the resonators 17 of the BP filter 5 (5A and / or 5B) and the BE filter 7 may be located on the same acoustic wave chip. For example, resonators 17 with similar resonant frequencies and / or antiresonant frequencies may be located on the same acoustic wave chip among multiple resonators. The resonators 17 of the BP filter 5 (5A and / or 5B) and the resonators 17 of the BE filter 7 may be identical or different in at least one of the material, cut angle, thickness, and thickness of the piezoelectric element 33a, and the excitation electrode. Inductors, capacitors, etc. may be located on the acoustic wave chip 33.

[0110] (4. Examples of communication devices) 8 is a block diagram showing an example of the configuration of a communication device 51 including an extractor 1. However, for convenience of explanation, only one BP filter 5 is shown. The explanation of the BP filter 5 here may be applied to, for example, each of the two BP filters.

[0111] The communication device 51 is configured to perform at least one of reception and transmission of a radio signal (both in the illustrated example) via the antenna 53. Specifically, the following is performed.

[0112] The antenna 53 is connected to the common terminal 3A (FIG. 1) of the extractor 1. The BP terminal 3P (FIG. 1) of the extractor 1 is connected to the first filter device 55. The BE terminal 3E (FIG. 1) of the extractor 1 is connected to the second filter device 57.

[0113] The first filter device 55 has, for example, a first branching filter 63 connected to the BP terminal 3P, and a first transmit filter 65 and a first receive filter 67 connected to the first branching filter 63. The first transmit filter 65 filters the transmit signal and inputs it to the first branching filter 63. The first receive filter 67 filters the receive signal from the first branching filter 63. The first branching filter 63 reduces the inflow of the transmit signal to the common terminal 3A into the first receive filter 67 and the inflow of the receive signal from the common terminal 3A into the first transmit filter 65. The pass bands of the first transmit filter 65 and the first receive filter 67 are included in the pass band of the BP filter 5.

[0114] The second filter device 57 has, for example, a second branching filter 69 connected to the BE terminal 3E, and a second transmit filter 71 and a second receive filter 73 connected to the second branching filter 69. The above-mentioned explanations of the first branching filter 63, the first transmit filter 65, and the first receive filter 67 may also be applied to the second branching filter 69, the second transmit filter 71, and the second receive filter 73. However, the pass bands of the second transmit filter 71 and the second receive filter 73 are included in the pass band of the BE filter 7.

[0115] The RF-IC 59 (Radio Frequency Integrated Circuit) performs modulation and frequency-upgrade processing on the baseband transmission signal, and inputs the high-frequency transmission signal to the transmission filters (65 and 71). The RF-IC 59 also performs demodulation and frequency-downgrade processing on the high-frequency reception signal from the reception filters (67 and 73).

[0116] The baseband processing unit 61 generates a baseband transmission signal based on predetermined processing and inputs it to the RF-IC 59. The baseband processing unit 61 also performs predetermined processing based on a baseband reception signal from the RF-IC 59. The content of the processing and the signal are arbitrary.

[0117] The communication device 51 may have any configuration in terms of hardware. For example, the extractor 1 may or may not share the multilayer substrate 31 with part or all of the first filter device 55 and the second filter device 57. The RF-IC 59 may be configured by multiple ICs instead of a single IC. The same applies to the baseband processing unit 61. Also, unlike the description here, the components that use signals in the passband of the BP filter 5 (either one of 5A and 5B) and the components that use signals in the passband of the BE filter 7 may be included in separate devices.

[0118] (5. Summary of embodiments) In a first aspect, the BE filter 7 (an example of a band attenuation filter) according to the embodiment includes a signal path 11 and parallel resonators 17E1 and 17E2 (an example of a first acoustic wave resonator and an example of a second acoustic wave resonator). The signal path 11 passes signals in a pass band B6 between non-overlapping attenuation bands B2A and B2B (an example of a first attenuation band and an example of a second attenuation band). The parallel resonator 17E1 connects the signal path 11 and the reference potential unit 13 and has a resonant frequency frE in the attenuation band B2A. The parallel resonator 17E2 connects the signal path 11 and the reference potential unit 13 and has a resonant frequency frE in the attenuation band B2B.

[0119] Therefore, for example, attenuation poles are formed in the attenuation bands B2A and B2B by the resonance points of the parallel resonators 17E1 and 17E2, and one BE filter 7 can accommodate two attenuation bands B2. Therefore, compared to an embodiment in which two BE filters corresponding to different attenuation bands B2 are connected in series, for example, it is easier to simplify and / or miniaturize the overall configuration.

[0120] The parallel resonators 17E1 and 17E2 may be connected to the same node 15 (15C) of the signal path 11.

[0121] In this case, the number of nodes 15 can be reduced compared to, for example, a configuration in which the parallel resonators 17E1 and 17E2 are connected to different nodes 15 (this configuration is also included in the technology according to the present disclosure). As a result, for example, this is advantageous for miniaturization and / or simplification. From another perspective, the influence of the number of parallel resonators 17E on the configuration of the series arm 21 is reduced, thereby improving the degree of freedom in designing the signal path 11. When the number of nodes 15 (the number of stages in the ladder configuration) is reduced, a reduction in insertion loss is expected. Furthermore, one of the parallel resonators 17E1 and 17E2 can function as a capacitor connected in parallel to the other. As a result, for example, Δf (the difference between the resonant frequency and the antiresonant frequency) of each parallel resonator 17E is reduced, thereby realizing an attenuation band B2 with a steep slope.

[0122] The BE filter 7 may have a plurality of parallel arms 23 that respectively connect a plurality of different nodes 15 of the signal path 11 to the reference potential unit 13. As illustrated in Fig. 9, each of at least two of the plurality of parallel arms 23 may include parallel resonators 17E1 and 17E2.

[0123] In this case, for example, attenuation poles utilizing the resonance points of the parallel resonator 17E can be distributed within the attenuation band B2, thereby improving the attenuation characteristics of the attenuation band B2.

[0124] The BE filter 7 may include series resonators 17B1 and 17B2 (an example of a third acoustic wave resonator and an example of a fourth acoustic wave resonator). The series resonator 17B2 may be located on the signal path 11 and may have an anti-resonance frequency faB in the attenuation band B2A. The series resonator 17B2 may be located on the signal path 11 and may have an anti-resonance frequency faB in the attenuation band B2B, and may be connected in series to the series resonator 17B1. The signal path 11 may be configured so as not to include a node 15 connected to the reference potential unit 13 between the series resonators 17B1 and 17B2.

[0125] In this case, the number of nodes 15 can be reduced compared to, for example, a configuration in which the series resonators 17B1 and 17B2 are connected to different nodes 15 (this configuration is also included in the technology of the present disclosure). As a result, for example, this is advantageous for miniaturization and / or simplification. Reducing the number of ladder-type stages is expected to reduce insertion loss. Furthermore, one of the series resonators 17B1 and 17B2 can function as a capacitor connected in series to the other. As a result, for example, the Δf of each series resonator 17B is reduced, thereby achieving an attenuation band B2 with a steep slope. By providing the parallel resonators 17E1 and 17E2 and the series resonators 17B1 and 17B2, for example, in each of the two attenuation bands B2, the series resonator 17B forms the slope on the high-frequency side, and the parallel resonator 17E forms the slope on the low-frequency side.

[0126] The BE filter 7 may include inductors 19A and 19B (an example of a first inductor and an example of a second inductor). The inductor 19A may connect a node 15A (an example of a first node) located on the opposite side of the series resonator 17B1 from the series resonator 17B2 in the signal path 11 to the reference potential unit 13. The inductor 19B may connect a node 15B (a second node) located on the opposite side of the series resonator 17B1 from the series resonator 17B2 in the signal path 11 to the reference potential unit 13. The signal path 11 may be configured such that no other node 15 connected to the reference potential unit 13 is located between the nodes 15A and 15B. The inductors 19A and 19B may be inductively coupled.

[0127] In this case, the widths of the pass bands B5 to B7 adjacent to the attenuation band B2 can be adjusted by adjusting the coupling coefficient, as described with reference to Fig. 6. For example, the widths of the pass bands B5 to B7 can be widened by setting the coupling coefficient to 0.05 or less, or even to a negative value.

[0128] In a second aspect, the BE filter 7 (an example of a band attenuation filter) includes a signal path 11, one or more parallel arms 23, and a skip path 24. The signal path 11 passes a signal in a pass band B6 between non-overlapping attenuation bands B2A and B2B (an example of a first attenuation band and an example of a second attenuation band). The one or more parallel arms 23 connect one or more nodes 15 of the signal path 11 to a reference potential unit 13. The skip path 24 branches off from the signal path 11 to bypass at least one of the one or more nodes 15 (node ​​15A) and merges with the signal path 11. The skip path 24 includes skip resonators 17D1 and 17D2 (an example of a fifth acoustic wave resonator and an example of a sixth acoustic wave resonator). The skip resonator 17D1 has an anti-resonance frequency faD in the attenuation band B2A. The skip resonator 17D2 has an anti-resonance frequency faD in the attenuation band B2B.

[0129] In this case, for example, a path for passing signals in the pass bands B5 to B7 is formed separately from the series resonators 17A and 17B. As a result, the pass characteristics of the pass bands B5 to B7 are improved and the width of the pass bands B5 to B7 is widened. Furthermore, the attenuation characteristics of the attenuation band B2 can be improved compared to an embodiment in which a capacitor is provided instead of the skip resonator 17D (this embodiment is also included in the technology according to the present disclosure). That is, it is easy to maintain the attenuation characteristics in the two attenuation bands B2 while improving the pass characteristics of the pass bands B5 to B7. One of the skip resonators 17D1 and 17D2 can function as a capacitor connected in parallel to the other. As a result, for example, it is easy to reduce Δf (the difference between the resonant frequency and the antiresonant frequency).

[0130] The absolute value of the impedance of the jump path 24 may be greater than the absolute value of the impedance of the portion of the signal path 11 bypassed by the jump path 24 (the series resonators 17A1, 17A2, 17B1, and 17B2) across each of the attenuation bands B2A and B2B.

[0131] In this case, for example, it is possible to reduce the possibility that the attenuation characteristics of the attenuation band B2 will be reduced due to a high-frequency signal passing through the skip resonator 17D.

[0132] The BE filter 7 may have an inductor 19A (an example of an inner inductor) connecting the node 15 (15A) bypassed by the jump path 24 to the reference potential unit 13, and an inductor 19B (an example of an outer inductor) connecting the node 15 (15B) not bypassed by the jump path 24 to the reference potential unit 13. The inductance of the inductor 19A may be larger than the inductance of the inductor 19B.

[0133] For example, a signal flowing from the common terminal 3A side to the BE terminal 3E side can reach the node 15A via the series resonator 17A, and can also reach the node 15A via the skip path 24 and the series resonator 17B. Therefore, by increasing the inductance of the inductor 19A connected to the node 15A, it is possible to reduce the likelihood that signals in the pass bands B5 to B7 will flow from the node 15A to the reference potential unit 13 via the inductor 19A.

[0134] The extractor 1 (or 1B) according to the embodiment includes a BE filter 7 according to the embodiment and a BP filter 5 (an example of a band-pass filter). The BE filter 7 connects a common terminal 3A and a BE terminal 3E (an example of a first terminal). The BP filter 5 connects the common terminal 3A and a BP terminal 3P (an example of a second terminal), and has a pass band B1A or B1B that overlaps at least a portion of the attenuation band B2 of the BE filter 7.

[0135] Since the extractor 1 includes the BE filter 7, various effects that the BE filter 7 provides can be enjoyed.

[0136] The extractor 1 (or 1B) may have multiple parallel arms 23 that connect different nodes 15 in the signal path 11 to the reference potential unit 13. The first parallel arm 23 from the common terminal 3A (the parallel arm 23 connected to node 15A in the example of FIG. 1) may be configured not to have an acoustic wave resonator. At least one of the second and subsequent parallel arms 23 from the common terminal 3A may have parallel resonators 17E1 and 17E2.

[0137] In this case, for example, an attenuation pole can be formed in the attenuation band B2 by the resonance point of the parallel resonator 17E. The parallel resonator 17E usually exhibits a larger change in impedance with respect to frequency than a capacitor or the like. Therefore, by positioning the parallel resonator 17E in the second or subsequent parallel arm 23, impedance matching on the common terminal 3A side can be facilitated.

[0138] The BP filter 5 (5A and / or 5B) may have a resonator 17 (e.g., a series resonator 17P or a parallel resonator 17S, an example of an elastic wave resonator) located on the piezoelectric body 33a where the resonator 17 (e.g., a parallel resonator 17E or a jump resonator 17D, an example of an elastic wave resonator) of the BE filter 7 is located.

[0139] In this case, for example, the piezoelectric body 33a is shared by the BE filter 7 and the BP filter 5. As a result, costs can be reduced compared to, for example, an embodiment in which the two are formed as completely separate piezoelectric bodies 33a (this embodiment is also included in the technology according to the present disclosure).

[0140] A communication device 51 according to the embodiment includes the extractor 1 (or 1B) according to the embodiment, an antenna 53, and an RF-IC 59 (an example of an IC). The antenna 53 is connected to a common terminal 3A. The RF-IC 59 may be connected to the common terminal 3A via a BP filter 5 and a BE filter 7, and may process at least one of a received signal from the common terminal 3A and a transmitted signal to the common terminal 3A.

[0141] Since the communication device 51 includes the BE filter 7, it is possible to enjoy various effects that the BE filter 7 provides.

[0142] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0143] For example, the BE filter does not have to be used as an extractor. The BE filter and extractor may or may not be used for wired communication. The BE filter may have two or more inductors in different series arms that are inductively coupled to each other.

[0144] The following concepts can be extracted from this disclosure. (Concept 1) a signal path that passes signals in a passband between the first and second non-overlapping attenuation bands; a first acoustic wave resonator that connects the signal path and a reference potential unit and has a resonance frequency in the first attenuation band; a second acoustic wave resonator that is connected in parallel with the first acoustic wave resonator, between the signal path and the reference potential unit, and has a resonant frequency in the second attenuation band; A band-reducing filter having (Concept 2) The first acoustic wave resonator and the second acoustic wave resonator are connected to the same node of the signal path. 10. The band attenuation filter of claim 1. (Concept 3) a plurality of parallel arms respectively connecting a plurality of mutually different nodes of the signal path to the reference potential unit; At least two of the parallel arms each include the first acoustic wave resonator and the second acoustic wave resonator. 3. The band attenuation filter of claim 2. (Concept 4) a third acoustic wave resonator located in the signal path and having an antiresonant frequency in the first attenuation band; a fourth acoustic wave resonator located in the signal path, having an anti-resonance frequency in the second attenuation band, and connected in series to the third acoustic wave resonator; The signal path does not have a node connected to the reference potential unit between the third acoustic wave resonator and the fourth acoustic wave resonator. The band attenuation filter according to any one of Concepts 1 to 3. (Concept 5) a first inductor connecting a first node located on the opposite side of the signal path from the fourth acoustic wave resonator with respect to the third acoustic wave resonator to the reference potential unit; a second inductor connecting a second node located on the signal path opposite the third acoustic wave resonator with respect to the fourth acoustic wave resonator to the reference potential unit; It has In the signal path, no other node connected to the reference potential section is located between the first node and the second node, The first inductor and the second inductor are inductively coupled. 5. The band attenuation filter of claim 4. (Concept 6) a bypass path that branches off from the signal path so as to bypass at least one of the one or more nodes connected to the reference potential portion of the signal path and merges with the signal path; The jump path is: a fifth acoustic wave resonator having an antiresonant frequency in the first attenuation band; a sixth acoustic wave resonator having an anti-resonance frequency in the second attenuation band and connected in series to the fifth acoustic wave resonator. The band attenuation filter according to any one of Concepts 1 to 6. (Concept 7) a signal path that passes signals in a passband between the first and second non-overlapping attenuation bands; one or more parallel arms connecting one or more nodes of the signal path to a reference potential portion; a jump path that branches off from the signal path so as to bypass at least one of the one or more nodes and then merges with the signal path; It has The jump path is: a fifth acoustic wave resonator having an antiresonant frequency in the first attenuation band; a sixth acoustic wave resonator having an anti-resonance frequency in the second attenuation band and connected in series to the fifth acoustic wave resonator. Band-attenuating filter. (Concept 8) The absolute value of the impedance of the jump path is greater than the absolute value of the impedance of the portion of the signal path bypassed by the jump path across each of the first attenuation band and the second attenuation band. 8. The band attenuation filter of claim 6 or 7. (Concept 9) an inner inductor connecting the node bypassed by the jump path and the reference potential section; an outer inductor connecting the node not bypassed by the jump path and the reference potential section; and The inductance of the inner inductor is greater than the inductance of the outer inductor. The band attenuation filter according to any one of Concepts 6 to 8. (Concept 10) the band attenuation filter according to Concept 1 or 7, connecting the common terminal and the first terminal; a first band-pass filter connecting the common terminal and a second terminal and having a first pass band at least partially overlapping with the first attenuation band; a second band-pass filter connecting the common terminal and a third terminal, the second band-pass filter having a second pass-band that at least partially overlaps with the second attenuation band and does not overlap with the first pass-band; An extractor having: (Concept 11) a plurality of parallel arms respectively connecting a plurality of mutually different nodes in the signal path to the reference potential section; the first parallel arm from the common terminal does not have an acoustic wave resonator, At least one of the parallel arms, which is the second or subsequent arm from the common terminal, has an acoustic wave resonator. 11. The extractor of claim 10. (Concept 12) At least one of the first band-pass filter and the second band-pass filter has an acoustic wave resonator located on a piezoelectric body on which the acoustic wave resonator of the band-reducing filter is located. 12. The extractor of claim 10 or 11. (Concept 13) An extractor according to any one of concepts 10 to 12; an antenna connected to the common terminal; an IC connected to the common terminal via the first band-pass filter, the second band-pass filter, and the band attenuation filter, and configured to process at least one of a received signal from the common terminal and a transmitted signal to the common terminal; A communication device having:

[0145] 7, 7B...BE filter (band attenuation filter), 11...signal path, 13...reference potential section, 15...node, 17...resonator (elastic wave resonator), 17D1...skipping resonator (fifth elastic wave resonator), 17D2...skipping resonator (sixth elastic wave resonator), 17E1...parallel resonator (first elastic wave resonator), 17E2...parallel resonator (second elastic wave resonator), 24...skipping path.

Claims

1. a signal path that passes signals in a passband between the first and second non-overlapping attenuation bands; a first acoustic wave resonator that connects the signal path and a reference potential unit and has a resonance frequency in the first attenuation band; a second acoustic wave resonator that is connected in parallel with the first acoustic wave resonator, the second acoustic wave resonator connecting the signal path and the reference potential unit, and that has a resonant frequency in the second attenuation band; A band-reducing filter having

2. The first acoustic wave resonator and the second acoustic wave resonator are connected to the same node of the signal path.

2. The band-reducing filter according to claim 1.

3. a plurality of parallel arms respectively connecting a plurality of mutually different nodes of the signal path to the reference potential unit; At least two of the parallel arms each include the first acoustic wave resonator and the second acoustic wave resonator.

3. The band-reducing filter according to claim 2.

4. a third acoustic wave resonator located in the signal path and having an antiresonance frequency in the first attenuation band; a fourth acoustic wave resonator located in the signal path, having an anti-resonance frequency in the second attenuation band, and connected in series to the third acoustic wave resonator; The signal path does not have a node connected to the reference potential unit between the third acoustic wave resonator and the fourth acoustic wave resonator.

2. The band-reducing filter according to claim 1.

5. a first inductor connecting a first node located on the opposite side of the signal path from the fourth acoustic wave resonator with respect to the third acoustic wave resonator to the reference potential unit; a second inductor connecting a second node located on the signal path opposite the third acoustic wave resonator with respect to the fourth acoustic wave resonator to the reference potential unit; It has In the signal path, no other node connected to the reference potential section is located between the first node and the second node, The first inductor and the second inductor are inductively coupled.

5. The band-reducing filter according to claim 4.

6. a jump path that branches off from the signal path so as to bypass at least one of the one or more nodes connected to the reference potential portion of the signal path and merges with the signal path; The jump path is: a fifth acoustic wave resonator having an antiresonant frequency in the first attenuation band; a sixth acoustic wave resonator having an anti-resonance frequency in the second attenuation band and connected in series to the fifth acoustic wave resonator.

2. The band-reducing filter according to claim 1.

7. a signal path that passes signals in a passband between the first and second non-overlapping attenuation bands; one or more parallel arms connecting one or more nodes of the signal path to a reference potential portion; a jump path that branches off from the signal path so as to bypass at least one of the one or more nodes and then merges with the signal path; It has The jump path is: a fifth acoustic wave resonator having an antiresonant frequency in the first attenuation band; a sixth acoustic wave resonator having an anti-resonance frequency in the second attenuation band and connected in series to the fifth acoustic wave resonator. Band-attenuating filter.

8. The absolute value of the impedance of the jump path is greater than the absolute value of the impedance of the portion of the signal path bypassed by the jump path across each of the first attenuation band and the second attenuation band.

8. A band-reducing filter according to claim 6 or 7.

9. an inner inductor connecting the node bypassed by the jump path and the reference potential section; an outer inductor connecting the node not bypassed by the jump path and the reference potential section; and The inductance of the inner inductor is greater than the inductance of the outer inductor.

8. A band-reducing filter according to claim 6 or 7.

10. a band attenuation filter according to claim 1 or 7, wherein the common terminal and the first terminal are connected; a first band-pass filter connecting the common terminal and a second terminal and having a first pass band at least partially overlapping with the first attenuation band; a second band-pass filter connecting the common terminal and a third terminal, the second band-pass filter having a second pass-band that at least partially overlaps with the second attenuation band and does not overlap with the first pass-band; An extractor having:

11. a plurality of parallel arms respectively connecting a plurality of mutually different nodes in the signal path to the reference potential section; the first parallel arm from the common terminal does not have an acoustic wave resonator, At least one of the parallel arms, which is the second or subsequent arm from the common terminal, has an acoustic wave resonator. The extractor of claim 10.

12. At least one of the first band-pass filter and the second band-pass filter has an acoustic wave resonator located on a piezoelectric body on which the acoustic wave resonator of the band-reducing filter is located. The extractor of claim 10.

13. An extractor according to claim 10; an antenna connected to the common terminal; an IC connected to the common terminal via the first band-pass filter, the second band-pass filter, and the band attenuation filter, and configured to process at least one of a received signal from the common terminal and a transmitted signal to the common terminal; A communication device having:

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