Band attenuation filter, extractor, and communication device

Abstract

To provide a band attenuation filter capable of adjusting the width of a pass band adjacent to an attenuation band.SOLUTION: In the band attenuation filter, the first acoustic wave resonator connects a first node and a second node included in the signal path to define the signal path. The first inductor connects the first node and the reference potential part. The second inductor connects the second node and the reference potential part. No other node connected to the reference potential part is located between the first node and the second node. The first inductor and the second inductor are differentially coupled.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.

[0003] In Patent Document 1, a band elimination filter is connected to a common terminal together with a band-pass filter to form an extractor. The attenuation band of the band elimination filter and the pass band of the band-pass filter overlap with each other. Patent Document 1 proposes inductively coupling an inductor located between the common terminal and the antenna with an inductor connected in series to multiple acoustic wave resonators of the band elimination filter on the side opposite the common terminal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 105589 Summary of the Invention [Problem to be solved by the invention]

[0005] What is needed is a band-reducing filter, extractor, and communication device that allows for adjustable widths of passbands adjacent to the attenuation band. [Means for solving the problem]

[0006] A band elimination filter according to one embodiment of the present disclosure includes one or more series arms that respectively connect a plurality of nodes located in a signal path to form the signal path, and a plurality of parallel arms that respectively connect the plurality of nodes to a reference potential section, wherein the one or more series arms include a first series arm having a first acoustic wave resonator that connects a first node and a second node of the plurality of nodes, and the plurality of parallel arms include a first parallel arm having a first inductor that connects the first node and the reference potential section, and a second parallel arm having a second inductor that connects the second node and the reference potential section, wherein no other node connected to the reference potential section is located between the first node and the second node in the signal path, and the first inductor and the second inductor are differentially coupled.

[0007] An extractor according to one embodiment of the present disclosure includes the above-mentioned band attenuation filter, which connects a common terminal and a first terminal, and a band-pass filter, which connects the common terminal and a second terminal and has a pass band that overlaps with at least a portion of the attenuation band of the attenuation band filter.

[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 bandpass 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 width of the pass band adjacent to the attenuation band can be adjusted. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a circuit diagram showing the configuration of an extractor according to the first embodiment. [Figure 2] FIG. 2 is a schematic perspective view illustrating inductive coupling in the band attenuation filter according to the first embodiment. [Figure 3]FIG. 2 shows the filter characteristics of the extractor of FIG. 1. [Figure 4] 4A and 4B are diagrams showing the influence of a change in the coupling coefficient of inductive coupling on the filter characteristics in the band attenuation filter according to the first embodiment. [Figure 5] 4 is a diagram showing the influence of a change in the coupling coefficient of inductive coupling on the width of the passband in the band attenuation filter according to the first embodiment. FIG. [Figure 6] 3A and 3B are diagrams illustrating the characteristics of a plurality of acoustic wave resonators included in the band elimination filter according to the first embodiment. [Figure 7] 10A and 10B are diagrams for explaining the action of a jump resonator included in a band attenuation filter; [Figure 8] 5A and 5B are diagrams illustrating the function of a parallel resonator included in the band attenuation filter. [Figure 9] FIG. 10 is a circuit diagram showing the configuration of an extractor according to a second embodiment. [Figure 10] FIG. 10 is a diagram showing the filter characteristics of the extractor of FIG. 9; [Figure 11] 10 is a diagram showing the influence of a change in the coupling coefficient of inductive coupling on the filter characteristics in the band attenuation filter according to the second embodiment. FIG. [Figure 12] 10 is a diagram showing the influence of a change in the coupling coefficient of inductive coupling on the width of the passband in the band attenuation filter according to the second embodiment. FIG. [Figure 13] 1A and 1B are diagrams showing an example of the structure of an extractor according to an embodiment. [Figure 14] FIG. 1 is a block diagram showing a main part of a communication device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the description of the embodiments, basically, only differences from the previously described embodiments will be described. Matters not specifically mentioned may be considered to be the same as the configurations of the previously described embodiments or may be inferred from the configurations of the previously described embodiments. Furthermore, for the sake of convenience, the same reference numerals may be used to designate corresponding or similar configurations in the multiple embodiments, even if there are differences.

[0012] 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.

[0013] (Overview of band-reducing filters) 1 is a circuit diagram showing the configuration of an extractor 1A according to the first embodiment. The extractor 1A is configured to pass signals in a predetermined pass band in the signal path between the common terminal 3A and the BP terminal 3P, and to attenuate signals in a predetermined attenuation band in the signal path between the common terminal 3A and the BE terminal 3E (from another perspective, to pass signals outside the attenuation band). The pass band and attenuation band ideally coincide with each other.

[0014] The extractor 1A has a BE filter 7A between the common terminal 3A and the BE terminal 3E, which attenuates signals in the attenuation band. The BE filter 7A has a signal path 11 connecting the common terminal 3A and the BE terminal 3E. The signal path 11 has a plurality of nodes 15 (15A to 15C in the illustrated example) connected to a reference potential section 13. The signals in the attenuation band are released to the reference potential section 13, for example.

[0015] Among the multiple nodes 15, adjacent nodes 15A and 15B (without any other nodes 15 connected to the reference potential section 13) are connected by a resonator 17 (more specifically, a series resonator 17B). The resonator 17 (17B) is, for example, an elastic wave resonator that utilizes elastic waves (the same applies to the other resonators 17 described below). The node 15A and the reference potential section 13 are connected by an inductor 19A. The node 15B and the reference potential section 13 are connected by an inductor 19B.

[0016] 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. 6. 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 relationship between the high and low frequencies may be reversed.

[0017] The anti-resonance frequency of the series resonator 17B is set higher than, for example, the cutoff frequency of the inductors 19A and 19B, thereby achieving filter characteristics in which a relatively narrow attenuation band (including the anti-resonance frequency) is located within a pass band higher than the cutoff frequency.

[0018] Here, inductors 19A and 19B are inductively coupled to each other. More specifically, they are differentially coupled to each other. As a result, as will be described later, it is easier to widen the pass band outside the attenuation band of BE filter 7A compared to a configuration in which they are not inductively coupled or a configuration in which they are constructively coupled.

[0019] Note that technical matters may be extracted from the embodiments from a different perspective than the above. In this case, unlike the above description, for example, differential coupling may not be performed, and summative coupling may be performed. The inductors 19A and 19B that are inductively coupled to each other may not be connected to the adjacent nodes 15A and 15B, and the series resonator 17B may not be interposed (another electronic element may be interposed instead of the series resonator 17B).

[0020] The above is an outline of the embodiment. The following will explain the outline in the following order. 1. Extractor according to the first embodiment 1.1. Extractors in general (Fig. 1 and Fig. 3) 1.2.BE filter (Figure 1) 1.2.1.BE Filters in General (Figure 1) 1.2.2. Inductors (Figures 1 and 2) 1.2.3.Effect of Inductive Coupling on Filter Characteristics (Figures 4 and 5) 1.2.4. Series Resonator (Figures 1 and 6) 1.2.5. Jump Paths (Jump Resonators) (Figures 1, 6, and 7) 1.2.6. Parallel Resonator (Figs. 1, 6 and 8) 2. Extractor according to the second embodiment (FIGS. 9 to 12) 3. Example of extractor structure (Figure 13) 4. Example of communication device (Figure 14) 5. Summary of embodiments

[0021] (1. Extractor according to the first embodiment) (1.1. Extractors in general) The extractor 1A is located between the common terminal 3A and the BP terminal 3P, and includes a BP filter 5 that passes signals in the passband, and the BE filter 7A. A matching circuit 9 for impedance matching may be interposed between the common terminal 3A and these filters.

[0022] 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.

[0023] 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.

[0024] In the illustrated example, more specifically, the BP filter 5 has a plurality of (four 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 (four 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.

[0025] 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 resonant frequencies of the series resonators 17S are substantially the same. This achieves filter characteristics with a passband 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.

[0026] 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 (resonators that do not utilize acoustic waves; the same applies below). In the illustrated example, inductors are provided at multiple positions, although reference numerals are omitted.

[0027] 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.

[0028] As described above, the resonator 17 included in each filter (5 or 7A) 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.

[0029] 3 is a diagram showing an example of the characteristics of the extractor 1A. The upper diagram shows the pass characteristic |S 31 |(dB), and more precisely, it shows the pass characteristic from the common terminal 3A to the BP terminal 3P. The lower graph shows the pass characteristic |S 21 |(dB), and more precisely, it shows the transmission characteristics from the common terminal 3A to the BE terminal 3E. The horizontal axis shows frequency f (GHz). The vertical axis shows the transmission characteristics.

[0030] The pass band B1 of the BP filter 5 and the attenuation band B2 of the BE filter 7A overlap with each other at least partially in their bandwidths. This portion may be, for example, 50% or more or 70% or more of the bandwidth. In the illustrated example, the BE filter 7A has a pass band B3 located on the low-frequency side of the attenuation band B2 and a pass band B4 located on the high-frequency side of the attenuation band B2. The frequencies and widths of these bands (B1 to B4) are arbitrary. In the illustrated example, these bands have relatively high frequencies. For example, the pass band B1 and the attenuation band B2 are located between 1 GHz and 3 GHz.

[0031] Although not shown, the characteristics of the BE filter 7A may not have one of the pass bands B3 and B4. For example, the characteristics of the BE filter 7A may be such that the attenuation band realized by the series resonator 17B is adjacent to the low-frequency side of the pass band of the high-pass filter realized by the inductors 19A and 19B.

[0032] (1.2.BE filter) (1.2.1.BE filters in general) As described above, the BE filter 7A has a signal path 11 in which a plurality of nodes 15 are connected to the reference potential unit 13. A portion of the signal path 11 that is divided into a plurality of nodes 15 is referred to as a series arm 21. The signal path 11 has at least one series arm 21 (four in the example of FIG. 1). A path connecting the node 15 and the reference potential unit 13 is referred to as a parallel arm 23. The plurality of parallel arms 23 connect the signal path 11 and the reference potential unit 13 in parallel with each other.

[0033] Just to be clear, parts that are considered to be substantially the same from an electrical perspective may be regarded as a single node. Therefore, for example, the nodes represented by dots in FIG. 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 section 13, node 15 may be regarded as being located at that end (series arm 21 is not located, but parallel arm 23 is connected). Although jump path 24 (described below) and inductor 19B are connected to the same node 15 (15B), their connection positions to signal path 11 may be separated from each other from a three-dimensional spatial perspective, not an electrical perspective.

[0034] The BE filter 7A may have paths (electronic elements) other than the series arm 21 and the parallel arm 23. In the example of Fig. 1, the BE filter 7A has (but does not have to have) a skip path 24 that branches off from the signal path 11 and merges with the signal path 11. The skip path 24 bypasses (skips over) at least one node 15 (one node 15B in the illustrated example), for example.

[0035] 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).

[0036] Of the multiple (four in the illustrated example) series arms 21, for example, at least one (multiple (three) in the illustrated example) has a resonator 17 (17A to 17C). Any one or more of the multiple series arms 21 may (or may not) have other electronic elements in addition to or instead of the resonator 17. Note that when the technology is extracted from a perspective different from that described in the overview of the embodiment, for example, all of the series arms 21 may have other electronic elements instead of the resonators 17.

[0037] The multiple series resonators 17A to 17C have, for example, approximately the same characteristics. As already described with respect to the anti-resonance frequency of the series resonator 17B, the series resonators 17A to 17C have anti-resonance frequencies in the attenuation band B2 of the BE filter 7A, and form attenuation poles.

[0038] Examples of electronic elements other than the resonator 17 included in the series arm 21 include an inductor, a capacitor, and an LC resonant circuit. When one series arm 21 has two or more electronic elements (including the resonator 17), the two or more electronic elements may be connected in series or in parallel.

[0039] 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 slope of the high frequency side of the pass band B4 and / or for impedance matching.

[0040] Of the multiple (three in the illustrated example) parallel arms 23, for example, at least two (two in the illustrated example) have inductors 19 (19A and 19B). Any one or more of the multiple parallel arms 23 may (or may not) have other electronic elements in addition to or instead of the inductor 19. Note that when the technology is extracted from a perspective different from that described in the overview of the embodiment, for example, all of the parallel arms 23 may have other electronic elements instead of the inductors 19.

[0041] Examples of electronic elements other than the inductor 19 included in the parallel arm 23 include a resonator 17 (an acoustic wave resonator), a capacitor, and an LC resonant circuit. When one parallel arm 23 has two or more electronic elements (including the inductor 19), the two or more electronic elements may be connected in series or in parallel.

[0042] In the illustrated example, the parallel arm 23 closest to the BE terminal 3E has a resonator 17 (parallel resonator 17E) instead of the inductor 19.

[0043] (1.2.2. Inductors) The characteristics (e.g., cutoff frequencies) of the inductors 19 (19A and 19B) included in the two or more parallel arms 23 may be the same as or different from each other. However, in this embodiment, as described above, the cutoff frequencies of all the inductors 19 are lower than the attenuation band B2 (or, from another perspective, the anti-resonance frequencies of the series resonators 17A to 17C). As a result, pass bands B3 and B4 are located on both sides of the attenuation band B2.

[0044] As illustrated in Fig. 9, which will be described later, the matching circuit 9 may have 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 7A, 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 7A, 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.

[0045] 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.

[0046] Furthermore, since an inductor used only for impedance matching does not normally define the slope on the low-frequency side of pass band B3 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.

[0047] The inductor 19 included in the BE filter 7A may contribute to impedance matching in addition to, or instead of, defining the filter characteristics. The inductor of the matching circuit 9 may 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 7A using the same or similar concept.

[0048] 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.

[0049] 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.

[0050] As described above, the inductive coupling is, for example, differential coupling, but may be summative coupling if technical matters from a different perspective than those described in the outline of the embodiment are extracted. When three or more inductors 19 are inductively coupled, only summative coupling, only differential coupling, or a combination of both may be adopted. The definitions of summative coupling and differential coupling for the inductors 19 of the two parallel arms 23 will be described below in the explanation of examples of the arrangement of the inductors 19.

[0051] FIG. 2 shows an example of an arrangement of two inductors 19 that are differentially coupled to each other.

[0052] In the example shown in the upper part of FIG. 2, 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.

[0053] 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.

[0054] In the example in the middle of Figure 2, 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.

[0055] In the example shown in the lower part of FIG. 2, the two inductors 19 overlap at least a portion 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.

[0056] The above explanation of the example in the lower part of Figure 2 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.

[0057] 2, 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.

[0058] The inductor 19 may be arranged in various ways to achieve differential or additive coupling other than the illustrated example.

[0059] For example, unlike the upper section of Figure 2, inductors 19 having the same direction of rotation 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.

[0060] Also, for example, unlike the middle section of Figure 2, inductors 19 with opposite winding directions may be arranged in parallel, 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.

[0061] 2, 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 unit 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.

[0062] 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).

[0063] 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.

[0064] 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 7A. 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.

[0065] (1.2.3. Effect of inductive coupling on filter characteristics) FIG. 4, like the lower part of FIG. 3, shows the pass characteristics of the BE filter 7A. The lower part of FIG. 4 is a partially enlarged view of the upper part of FIG. 4. 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.

[0066] 4 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 bands where | is -3 dB or more are treated as passbands B3 and B4. As shown in this figure, the change in the coupling coefficient causes |S 21 The frequency at which | is -3dB varies.

[0067] Figure 5 shows the coupling coefficient and |S 21 5 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 B3, and the lower limit HL and upper limit HH of the pass band B4, as shown in the legend and in the diagram in the upper right (schematic representation of the lower part of FIG. 3). FIG. 5 was obtained based on FIG. 4.

[0068] As shown in Figure 5 (and Figure 4), the lower limit LL decreases as the coupling coefficient decreases. On the other hand, the upper limit LH does not change significantly even when the coupling coefficient changes. Therefore, the smaller the coupling coefficient, the wider the passband B3 becomes.

[0069] Furthermore, when the coupling coefficient is negative, the lower limit HL does not change significantly even if the coupling coefficient is changed, but when the coupling coefficient is positive, the lower limit HL increases as the coupling coefficient increases. More specifically, there is a difference between values ​​below 0.05 and values ​​above 0.10. The upper limit HH increases as the coupling coefficient decreases. Therefore, the width of the passband B4 increases as the coupling coefficient decreases.

[0070] In this way, the width, lower limit, and / or upper limit of attenuation band B2, pass band B3, and / or pass band B4 can be adjusted by inductive coupling. For example, from the viewpoint of widening pass bands B3 and B4, the coupling coefficient may be set to 0.05 or less (but not including 0), or even a negative value.

[0071] The reason why the widths of the passbands B3 and B4 become wider as the coupling coefficient becomes smaller is, for example, that a path that is essentially connected in parallel to the signal path 11 is formed by inductive coupling, 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.

[0072] 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.

[0073] (1.2.4. Series resonator) FIG. 6 is a diagram showing an example of the characteristics of the resonator 17 of the BE filter 7A. The upper part of FIG. 6, like the lower part of FIG. 4, roughly shows the pass characteristics of the BE filter 7A in the attenuation band B2. The lower part of FIG. 6 shows the characteristics of the resonator 17 of the BE filter 7A. The horizontal axis of the lower part of the diagram is the same as the horizontal axis of the upper part of the diagram. The vertical axis of the lower part of the diagram is the absolute value of the impedance |Z| (Ω). The symbols in the legend match those in FIG. 1.

[0074] 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.

[0075] 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.

[0076] (1.2.5. Jump Path (Jump Resonator)) 1 (the skip resonator 17D), as described above, skips over one or more nodes 15 connected to the reference potential section 13. As can be understood from the above description regarding the node potentials, the fact that the skip path 24 bypasses the node 15A means, from another perspective, that the skip path 24 is connected in parallel to at least two electronic elements (the series resonators 17A and 17B in the example of FIG. 1) that are connected in series across the node 15A.

[0077] By providing the skip path 24, for example, a path through which signals of pass bands B3 and B4 flow is formed in parallel with the signal path 11. This improves the pass characteristics in the pass bands B3 and B4. 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.

[0078] The jump path 24 may bypass at least one resonator 17 included in the signal path 11. In the example of Fig. 1, the jump path 24 is connected in parallel to two series resonators 17A and 17B (two series arms 21 from another perspective). Unlike the example shown in the figure, the jump path 24 may be connected in parallel to one resonator 17 and another electronic element that are connected in series across the node 15B, or may be connected in parallel to three or more electronic elements that may or may not include one resonator 17.

[0079] 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).

[0080] 1, the node 15 skipped by the skip path 24 is the node 15 (15A) to which one of the two inductors 19 (19A in the illustrated example) that are inductively coupled to each other is connected. One end of the skip path 24 is connected to the node 15 (15B) to which the other of the 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 the path that is substantially formed by the inductive coupling.

[0081] 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 resonator 17D). The jump path 24 may include other electronic elements instead of or in addition to the jump resonator 17D. 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.

[0082] The specific characteristics of the jump resonator 17D may be set appropriately, for example, as follows.

[0083] 6, |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, |Z| of the skipped resonator 17D is arbitrary.

[0084] |Z| of the resonator 17 can be adjusted by, for example, the capacitance of the excitation electrode (for example, the IDT electrode) of the resonator 17. Therefore, for example, in the above description, the term |Z| may be replaced with the term capacitance.

[0085] As described above, the signal path 11 and the skip path 24 may include electronic elements other than the resonator 17. Therefore, 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.

[0086] The anti-resonance frequency faD of the skip resonator 17D is located in the attenuation band B2. The specific value thereof 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.

[0087] By including the skip path 24 in the skip resonator 17D, it is possible to reduce degradation of the characteristics in the attenuation band B2, compared to, for example, an embodiment in which a capacitor is provided instead of the skip resonator 17D (this embodiment may also be included in the technology according to the present disclosure). Specifically, this is as follows.

[0088] FIG. 7 is a diagram similar to FIG. 4, showing the difference in characteristics of the BE filter 7A depending on whether or not the skip resonator 17D is included. The line marked with R1 in the legend indicates the characteristics of the BE filter 7A provided with the skip resonator 17D. The line marked with C1 in the legend indicates the characteristics of the BE filter 7A provided with a capacitor instead of the skip resonator 17D. The capacitance of the capacitor is set so that the impedances related to R1 and C1 are equal. Other than the conditions related to the skip resonator 17D, the conditions for the two examples are the same. The coupling coefficient of inductors 19A and 19B is -0.20.

[0089] As shown in the upper part of Fig. 7, there is no significant difference in the characteristics of the two examples in passbands B3 and B4. As shown in the lower part of Fig. 7, in attenuation band B2, example R1 attenuates more than example C1 on the high frequency side (especially the peak located at 2.44 GHz to 2.48 GHz), and the characteristics are improved. The reason for this is that, for example, while the impedance of a capacitor decreases as the frequency increases, the jump resonator 17D can increase the impedance at and around the anti-resonance frequency.

[0090] (1.2.6.Parallel resonator) 1, the BE filter 7A may include a parallel resonator 17E. This can improve the attenuation characteristics in the attenuation band B2, for example. Specifically, this is as follows.

[0091] 6, the resonant frequency frE of the parallel resonator 17E is located, for example, in the attenuation band B2, which allows signals within the attenuation band B2 (more specifically, signals at the resonant frequency frE and frequencies nearby) to easily flow to the reference potential section 13, thereby improving the attenuation characteristics.

[0092] 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 the one or more antiresonant 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.

[0093] 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.

[0094] The anti-resonant frequency (symbol omitted) of the parallel resonator 17E is arbitrary and may be located, for example, in the attenuation band B2 (in the illustrated example) or in the pass band B4. |Z| of the parallel resonator 17E is also arbitrary and may be smaller, equal to, or larger than the |Z| of all or some of the series resonators 17A to 17C when comparing their maximum values ​​or minimum values ​​(in the illustrated example).

[0095] FIG. 8 is a diagram similar to FIG. 7, showing the difference in characteristics of the BE filter 7A depending on whether or not the parallel resonator 17E is present. The line marked with R1 in the legend indicates the characteristics of the BE filter 7A provided with the parallel resonator 17E (the same as the characteristics of R1 in FIG. 7). The line marked with C2 in the legend indicates the characteristics of the BE filter 7A provided with a capacitor instead of the parallel resonator 17E. The capacitance of the capacitor is set so that the impedances related to R1 and C2 are equivalent. The conditions for the two examples are the same except for the conditions related to the parallel resonator 17E.

[0096] As shown in the upper part of Fig. 8, there is no significant difference in the characteristics of the two examples in pass bands B3 and B4. As shown in the lower part of Fig. 8, in attenuation band B2, example R1 attenuates more than example C2 on the low frequency side (especially around 2.39 GHz), resulting in improved characteristics. The reason for this is that although a capacitor can pass signals on the higher frequency side than the cutoff frequency, which is located on the higher frequency side of pass band B4, to the reference potential section 13, it cannot form an attenuation pole at an arbitrary position, as with the resonant frequency of the parallel resonator 17E.

[0097] In the BE filter 7A 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.

[0098] 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 7A 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.

[0099] (2. Extractor according to the second embodiment) FIG. 9 is a circuit diagram showing the configuration of an extractor 1B according to the second embodiment, and corresponds to FIG. 1 according to the first embodiment.

[0100] The extractor 1B has two or more (two in the illustrated example) BP filters 5 (5A and 5B) with different passbands. The BE filter 7B is configured to attenuate signals in two or more (two) attenuation bands corresponding to the two or more (two) passbands. Specifically, this is as follows.

[0101] The BP filters 5A and 5B may have any configuration as long as their passbands do not overlap. For example, the BP filters 5A and 5B may have the same configuration (excluding specific design values ​​for different passbands) or different configurations. For example, as in the example of FIG. 9, the BP filters 5A and 5B may be ladder-type acoustic wave filters with the same number of stages, acoustic wave filters with different numbers of stages or types (e.g., ladder type and multimode type), or filters of different types, whether they are acoustic wave filters or not.

[0102] The BE filter 7B has two or more (two) resonators 17 at the position where one resonator 17 was provided in the first embodiment. As indicated by the presence or absence of hatching, one of the two resonators 17 at each position is associated with an attenuation band corresponding to the pass band of the BP filter 5A, and the other is associated with an attenuation band corresponding to the pass band of the BP filter 5B. The two attenuation bands do not overlap (there is a pass band between them). The description of the resonator 17 in the first embodiment may be applied to each of the two resonators 17 at each position.

[0103] A more detailed correspondence is shown below using symbols. 17A: 17A1 / 17A2 17B: 17B1 / 17B2 17C: 17C1 / 17C2 17D: 17D1 / 17D2 17E: 17E1 / 17E2

[0104] In each series arm 21, two resonators 17 (17A1 and 17A2, 17B1 and 17B2, or 17C1 and 17C2) are connected in series with each other. The jump resonators 17D1 and 17D2 are connected in series with each other. The parallel resonators 17E1 and 17E2 are connected in parallel with each other. The parallel resonators 17E1 and 17E2 may be regarded as one parallel arm 23 connecting the same node 15C and the reference potential unit 13. The relationship between the frequencies and the connection order of the two types of resonators 17 connected in series with each other is arbitrary. The connection order of the two types of resonators 17 may be different between multiple series arms 21.

[0105] The illustrated example 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).

[0106] In the extractor 1B having the above configuration, for example, as in the first embodiment, the width of the passband can be adjusted by inductive coupling of the inductor 19. Specifically, this is as follows.

[0107] 10 is a diagram showing an example of the characteristics of the extractor 1B, and corresponds to FIG. 3 of the first embodiment. The upper diagram shows the pass characteristic |S 31 The graph in the middle shows the pass characteristic |S (dB) of the BP filter 5B, and more precisely, the pass characteristic from the common terminal 3A to the BP terminal 3P1. 41 The graph in the lower half shows the pass characteristic |S (dB) of the BE filter 7B, and more precisely, the pass characteristic from the common terminal 3A to the BP terminal 3P2. 21 |(dB), and more strictly speaking, it shows the passing characteristics from the common terminal 3A to the BE terminal 3E.

[0108] As described above, the BE filter 7B has attenuation bands B2A and B2B that correspond to (at least partially overlap) the pass band B1A of the BP filter 5A and the pass band B1B of the BP filter 5B, respectively. In the illustrated example, the BE filter 7B also has a pass band B5 located on the low-frequency side of the attenuation band B2A, a pass band B6 located between the attenuation bands B2A and B2B, and a pass band B7 located on the high-frequency side of the attenuation band B2B.

[0109] 11 is a diagram showing the pass characteristic of the BE filter 7B, and corresponds to FIG. 4 of the first embodiment. As shown in this diagram, in the second embodiment, as in the first embodiment, the change in the coupling coefficient causes |S 21 The frequency at which | is -3dB varies.

[0110] FIG. 12 shows the coupling coefficient and |S 21 10(a) and 10(b) show the relationship between the frequency at which || becomes -3 dB and the frequency at which || becomes -3 dB, and correspond to FIG. 5 of the first embodiment. The plots and lines in the figure indicate the lower limit value LL and upper limit value LH of the pass band B5, the lower limit value ML and upper limit value MH of the pass band B6, and the lower limit value HL and upper limit value 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. 10).

[0111] 12, for example, in the second embodiment as well, when the coupling coefficient is made smaller (for example, when it is made 0.05 or less or a negative value), the width of the passband tends to become wider. Specifically, this is as follows.

[0112] As in the first embodiment, the lower limit LL decreases as the coupling coefficient decreases. Similarly to the first embodiment, the upper limit LH does not change significantly even when the coupling coefficient changes. Therefore, the smaller the coupling coefficient, the wider the pass band B5. 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 pass band B5 is not ensured.

[0113] When the coupling coefficient is negative, the lower limit ML does not change significantly even if the coupling coefficient is changed, but when the coupling coefficient is positive, the lower limit ML increases as the coupling coefficient increases. Similarly to the upper limit LH in the first embodiment, the upper limit MH does not change significantly even if the coupling coefficient is changed. Therefore, the smaller the coupling coefficient, the wider the passband B6.

[0114] As in the first embodiment, when the coupling coefficient is negative, the lower limit HL does not change significantly even if the coupling coefficient is changed, but when the coupling coefficient is positive, the lower limit HL increases as the coupling coefficient increases. Unlike the first embodiment, the upper limit HH does not change significantly even if the coupling coefficient is changed. Therefore, the smaller the coupling coefficient, the wider the width of the pass band B7.

[0115] (3. Example of extractor structure) Here, the extractor 1A according to the first embodiment is taken as an example, but the same may be applied to the second embodiment.

[0116] 13 is a schematic exploded perspective view showing an example of the structure of the extractor 1 A. The extractor 1 A has, for example, a multilayer substrate 31 and an acoustic wave chip 33 mounted on the multilayer substrate 31.

[0117] 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 1A has.

[0118] 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. 13, the IDT electrode 33b is schematically represented by a symbol of two interlocking prongs.

[0119] 13, the resonators 17 (e.g., all of them) of the BP filter 5 and the resonators 17 (e.g., all of them) of the BE filter 7A 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 7A 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 resonators 17 of the BP filter 5 and the resonators 17 of the BE filter 7A may have the same thickness as the IDT electrodes 33b (excitation electrodes).

[0120] Unlike the above description, for example, the BP filter 5 and the BE filter 7A 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 and the BE filter 7A may be located on the same acoustic wave chip. For example, resonators 17 with similar resonant frequencies and / or antiresonant frequencies may be distributed to the same acoustic wave chip among multiple chips. The resonators 17 of the BP filter 5 and the resonators 17 of the BE filter 7A may be identical or different in at least one of the material, cut angle, and thickness of the piezoelectric element 33a, and the thickness of the excitation electrode. Inductors, capacitors, etc. may be located on the acoustic wave chip 33.

[0121] (4. Examples of communication devices) 14 is a block diagram showing an example of the configuration of a communication device 51 including an extractor 1 (for example, 1A or 1B). Note that the BE filter 7 in the figure is, for example, a BE filter 7A or 7B. For convenience, the symbols in the first embodiment may be used.

[0122] 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.

[0123] 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.

[0124] 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 B1 of the BP filter 5.

[0125] 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 B3 or B4 of the BE filter 7A.

[0126] 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).

[0127] 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.

[0128] 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 component that uses signals in the passband B1 of the BP filter 5 and the component that uses signals in the passband B3 or B4 of the BE filter 7A may be included in separate devices.

[0129] (5. Summary of embodiments) In the following description, for convenience, the symbols of either the first or second embodiment (particularly the first embodiment) may be used unless otherwise specified. However, unless a contradiction or the like arises, the second embodiment may be considered to be the same.

[0130] The BE filter 7 (7A or 7B) has one or more series arms 21 and a plurality of parallel arms 23. The one or more series arms 21 respectively connect a plurality of nodes 15 located on the signal path 11 to each other to form the signal path 11. The plurality of parallel arms 23 respectively connect the plurality of nodes 15 to the reference potential unit 13. The one or more series arms 21 include a series arm 21 (an example of a first series arm) having a resonator 17 (17B in FIG. 1 , 17B1 or 17B2 in FIG. 9 , an example of a first acoustic wave resonator) that connects a node 15A (an example of a first node) and a node 15B (an example of a second node) among the plurality of nodes 15. The plurality of parallel arms 23 include a parallel arm 23 (an example of a first parallel arm) having an inductor 19A (an example of a first inductor) and a parallel arm 23 (an example of a second parallel arm) having an inductor 19B (an example of a second inductor). Inductor 19A connects node 15A and the reference potential section 13. Inductor 19B connects node 15B and the reference potential section 13. In signal path 11, no other node 15 connected to the reference potential section 13 is located between node 15A and node 15B (although there may be nodes that are not connected to the reference potential section 13). Inductor 19A and inductor 19B are differentially coupled.

[0131] In this case, for example, as described in the overview of the embodiment and with reference to Fig. 5 and Fig. 12, it is easy to widen the width of the passbands B3 and B4 (or B5 to B7). Furthermore, because the nodes 15A and 15B are adjacent to each other, the path formed by differential coupling can reduce the frequency difference between the resonant frequency and the anti-resonant frequency, as with a capacitor connected in parallel to the series resonator 17B. This allows, for example, the slope of the high-frequency side (or low-frequency side) of the attenuation band B2 to be steeper.

[0132] The BE filter 7A may include a resonator 17 (17E in FIG. 1, 17E1 or 17E2 in FIG. 9, an example of a second acoustic wave resonator) connecting any one of the plurality of nodes 15 to the reference potential section 13. The resonant frequency frE of the parallel resonator 17E may be set lower than the antiresonant frequency faB of the series resonator 17B.

[0133] In this case, for example, the attenuation band B2 is formed by the anti-resonance point of the series resonator 17B, while the slope on the low frequency side of the attenuation band B2 is formed by the resonance point of the parallel resonator 17E. In other words, compared to a case where the resonance frequency frE is equal to or higher than the anti-resonance frequency faB (this case is also included in the technology according to the present disclosure), it is possible to reduce the likelihood that the parallel resonator 17E will degrade the characteristics on the high frequency side of the attenuation band B2, or that the series resonator 17B will degrade the characteristics on the low frequency side of the attenuation band B2.

[0134] The one or more series arms 21 may include a plurality of series arms 21 each connecting three or more nodes 15. The plurality of parallel arms 23 may include a parallel arm 23 (an example of a third parallel arm) having a resonator 17 (17E in FIG. 1 , 17E1 or 17E2 in FIG. 9 , an example of a second acoustic wave resonator) connecting a node 15 different from nodes 15A and 15B among the three or more nodes 15 to the reference potential unit 13.

[0135] In this case, compared to, for example, a case where the parallel resonator 17E is connected to the node 15B instead of the node 15C (this case is also included in the technology according to the present disclosure), the possibility that a signal within the passband that flows from the inductor 19A to the inductor 19B via inductive coupling will flow to the reference potential section 13 via the parallel resonator 17E is reduced, thereby improving the effect of inductive coupling.

[0136] The BE filter 7A may have a skip path 24. The skip path 24 may branch off from the signal path 11 and merge with the signal path 11 so as to bypass at least one of the plurality of nodes 15 connected to the reference potential unit 13 and a resonator 17 (17A or 17B in the example of FIG. 1, 17A1, 17A2, 17B1, or 17B2 in the example of FIG. 9, an example of an acoustic wave resonator) included in one of the plurality of series arms 21. The skip path 24 may have a skip resonator 17D (an example of a third acoustic wave resonator).

[0137] In this case, for example, paths that pass signals in pass bands B3 and B4 are formed separately from the series resonators 17A and 17B. As a result, the pass characteristics of pass bands B3 and B4 are improved and the widths of pass bands B3 and B4 are widened. Furthermore, as described with reference to FIG. 7, the attenuation characteristics at and near the anti-resonance frequency faD (for example, the high-frequency side of attenuation band B2) can be improved compared to an embodiment in which a capacitor is provided instead of the jump resonator 17D (this embodiment is also included in the technology according to the present disclosure).

[0138] The capacitance of the skip resonator 17D (or 17D1 or 17D2) may be smaller than the capacitance of the resonator 17 (17A or 17B in the example of Figure 1, 17A1, 17A2, 17B1 or 17B2 in the example of Figure 9, an example of an elastic wave resonator) bypassed by the skip path 24.

[0139] And / or, the absolute value of the impedance of the jump path 24 may be made larger than the absolute value of the impedance of the portion of the signal path 11 bypassed by the jump path 24 (for example, the combined impedance of the series resonators 17A and 17B in the example of FIG. 1) over the entire attenuation band (B2 in the example of FIG. 3, and the entire B2A and B2B in the example of FIG. 10).

[0140] In these cases, 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.

[0141] The BE filter 7A may have an inductor 19A (an example of an inner inductor) connecting the node 15 (15A) bypassed by the jump path 24 and 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 and the reference potential unit 13. The inductance of the inductor 19A may be larger than the inductance of the inductor 19B.

[0142] For example, a signal flowing from the common terminal 3A to the BE terminal 3E 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 B3 and B4 will flow from the node 15A to the reference potential unit 13 via the inductor 19A.

[0143] The inductor (inner inductor) connected to the node 15 skipped by the skip path 24 may be the inductor 19A (an example of a first inductor) involved in the inductive coupling. Similarly, the inductor (outer inductor) connected to the node 15 not skipped by the skip path 24 may be the inductor 19B (an example of a second inductor) involved in the inductive coupling, or an inductor (not shown) connected to a node 15 (e.g., node 15C) located on the opposite side of node 15B (an example of a second node) from node 15A (an example of a first node).

[0144] For example, a signal flowing from the common terminal 3A side to the BE terminal 3E side can flow to the reference potential section 13 via the bypass path 24, inductor 19B, the path due to inductive coupling, and inductor 19A. Therefore, by increasing the inductance of inductor 19A as described above, it is possible to reduce the likelihood that signals in the pass bands B3 and B4 will flow to the reference potential section 13 via inductor 19A.

[0145] As illustrated in the second embodiment, the series arm 21 sandwiched between the inductively coupled inductors 19A and 19B may include a series resonator 17B1 (an example of a first acoustic wave resonator) and a series resonator 17B2 (an example of a fourth acoustic wave resonator). The series resonator 17B1 may have an anti-resonant frequency in an attenuation band B2A (an example of a first attenuation band). The series resonator 17B2 may have an anti-resonant frequency in an attenuation band B2B (an example of a second attenuation band) that does not overlap with the attenuation band B2A, and may be connected in series with 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.

[0146] In this case, for example, the BE filter 7B can achieve two attenuation bands B2A and B2B. Furthermore, compared to an embodiment in which a node 15 connected to the reference potential unit 13 is provided between the series resonators 17B1 and 17B2 (if technical matters are extracted from a perspective different from that described in the summary of the embodiments, such an embodiment is also acceptable), the configuration can be simplified and / or miniaturized. The number of ladder stages can be reduced, thereby reducing insertion loss. One resonator 17 functions as a capacitor connected to the other resonator 17, thereby reducing Δf (the difference between the resonant frequency and the antiresonant frequency). As a result, for example, the slope of the attenuation band B2 can be made steeper. The series arm 21 includes two series resonators 17B1 and 17B2 connected in series, which increases inductive impedance. However, this effect can be compensated for by inductive coupling between the inductors 19A and 19B on both sides of the series arm 21.

[0147] The extractor 1A (or 1B) according to the embodiment includes a BE filter 7A according to the embodiment and a BP filter 5 (an example of a band-pass filter). The BE filter 7A 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 B1 that overlaps at least a part of an attenuation band B2 of the BE filter 7A.

[0148] The extractor 1A includes the BE filter 7A, and therefore can enjoy the various effects that the BE filter 7A provides.

[0149] The extractor 1A (or 1B) may be configured so that the first parallel arm 23 from the common terminal 3A (the parallel arm 23 connected to the node 15A in the example of FIG. 1) does not have an acoustic wave resonator. At least one of the second and subsequent parallel arms 23 from the common terminal 3A may have a parallel resonator 17E (an example of an acoustic wave resonator).

[0150] 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.

[0151] The BP filter 5 may have a resonator 17 (for example, a series resonator 17S and / or a parallel resonator 17P, which is an example of an acoustic wave resonator) located on the piezoelectric body 33a where the series resonator 17B is located.

[0152] In this case, for example, the piezoelectric body 33a is shared by the BE filter 7A 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).

[0153] A communication device 51 according to the embodiment includes an extractor 1A (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.

[0154] Since the communication device 51 includes the BE filter 7A, it is possible to enjoy various effects that the BE filter 7A provides.

[0155] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0156] For example, the BE filter does not have to be used in the extractor. The BE filter and the extractor may or may not be used for wired communication. The BE filter may have filter characteristics in which the attenuation band is located within the pass band of the high-pass filter. If technical matters different from the viewpoints described in the summary of the embodiments are extracted, the inductor in the parallel arm is not a mandatory requirement. The BE filter may have filter characteristics in which the attenuation band is located within the pass band of the low-pass filter.

[0157] The following concepts can be extracted from this disclosure.

[0158] (Concept 1) one or more series arms that connect a plurality of nodes located on a signal path to form the signal path; a plurality of parallel arms respectively connecting the plurality of nodes to a reference potential unit; It has the one or more series arms include a first series arm having a first acoustic wave resonator connecting a first node and a second node of the plurality of nodes; The plurality of parallel arms include: a first parallel arm having a first inductor connecting the first node and the reference potential unit; a second parallel arm having a second inductor connecting the second node and the reference potential unit; 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 differentially coupled. Band-attenuating filter. (Concept 2) a second acoustic wave resonator connecting any one of the plurality of nodes to the reference potential unit, The resonant frequency of the second acoustic wave resonator is lower than the anti-resonant frequency of the first acoustic wave resonator. 10. The band attenuation filter of claim 1. (Concept 3) the one or more series arms include a plurality of series arms each connecting three or more of the nodes, The plurality of parallel arms include a third parallel arm having a second acoustic wave resonator that connects a node different from the first node and the second node among the three or more nodes to the reference potential unit. 3. The band attenuation filter according to claim 1 or 2. (Concept 4) a bypass path branching from the signal path and merging into the signal path so as to bypass at least one of the plurality of nodes connected to the reference potential section and an elastic wave resonator included in any of the plurality of series arms, The jump path includes a third acoustic wave resonator. The band attenuation filter according to any one of Concepts 1 to 3. (Concept 5) The capacitance of the third acoustic wave resonator is smaller than the capacitance of the acoustic wave resonator bypassed by the jump path. 5. The band attenuation filter of claim 4. (Concept 6) The absolute value of the impedance of the bypass path is greater than the absolute value of the impedance of the portion of the signal path bypassed by the bypass path over the attenuation band of the band attenuation filter. 6. The band attenuation filter of claim 4 or 5. (Concept 7) 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 4 to 6. (Concept 8) the inner inductor is the first inductor, The outer inductor is the second inductor or an inductor connected to the node located on the opposite side of the second node from the first node. 8. The band attenuation filter of claim 7. (Concept 9) The first series arm includes: the first acoustic wave resonator having an anti-resonance frequency in a first attenuation band; a fourth acoustic wave resonator having an anti-resonance frequency in a second attenuation band that does not overlap with the first attenuation band and connected in series with the first acoustic wave resonator; The signal path does not have a node connected to the reference potential unit between the first acoustic wave resonator and the fourth acoustic wave resonator. The band attenuation filter according to any one of Concepts 1 to 8. (Concept 10) a band attenuation filter according to concept 1, connecting the common terminal and the first terminal; a band-pass filter connecting the common terminal and a second terminal and having a pass band overlapping at least a part of an attenuation band of the attenuation band filter; An extractor having: (Concept 11) 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) The band-pass filter includes an acoustic wave resonator located on the piezoelectric body on which the first acoustic wave resonator 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 band-pass filter and the band-reducing filter, for processing at least one of a received signal from the common terminal and a transmitted signal to the common terminal; A communication device having:

[0159] 7, 7A, 7B...BE filter (band attenuation filter), 11...signal path, 13...reference potential section, 15...node, 15A...node (first node), 15B...node (second node), 17...resonator (elastic wave resonator), 17B...resonator (first elastic wave resonator), 19...inductor, 19A...inductor (first inductor), 19B...inductor (second inductor), 21...series arm, 23...parallel arm.

Claims

1. one or more series arms that connect a plurality of nodes located on a signal path to form the signal path; a plurality of parallel arms respectively connecting the plurality of nodes to a reference potential unit; It has the one or more series arms include a first series arm having a first acoustic wave resonator connecting a first node and a second node of the plurality of nodes; The plurality of parallel arms include: a first parallel arm having a first inductor connecting the first node and the reference potential unit; a second parallel arm having a second inductor connecting the second node and the reference potential unit; 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 differentially coupled. Band-attenuating filter.

2. a second acoustic wave resonator connecting any one of the plurality of nodes to the reference potential unit, The resonant frequency of the second acoustic wave resonator is lower than the anti-resonant frequency of the first acoustic wave resonator.

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

3. the one or more series arms include a plurality of series arms each connecting three or more of the nodes, The plurality of parallel arms include a third parallel arm having a second acoustic wave resonator connecting a node different from the first node and the second node among the three or more nodes to the reference potential unit.

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

4. a bypass path branching from the signal path and merging into the signal path so as to bypass at least one of the plurality of nodes connected to the reference potential section and an elastic wave resonator included in any of the plurality of series arms, The jump path includes a third acoustic wave resonator.

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

5. The capacitance of the third acoustic wave resonator is smaller than the capacitance of the acoustic wave resonator bypassed by the jump path.

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

6. The absolute value of the impedance of the bypass path is greater than the absolute value of the impedance of the portion of the signal path bypassed by the bypass path over the attenuation band of the band attenuation filter.

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

7. 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.

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

8. the inner inductor is the first inductor, The outer inductor is the second inductor or an inductor connected to the node located on the opposite side of the second node from the first node.

8. The band-reducing filter according to claim 7.

9. The first series arm includes: the first acoustic wave resonator having an anti-resonance frequency in a first attenuation band; a fourth acoustic wave resonator having an anti-resonance frequency in a second attenuation band that does not overlap with the first attenuation band and connected in series with the first acoustic wave resonator; The signal path does not have a node connected to the reference potential unit between the first acoustic wave resonator and the fourth acoustic wave resonator.

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

10. a band attenuation filter according to claim 1, wherein the common terminal and the first terminal are connected; a band-pass filter connecting the common terminal and a second terminal and having a pass band overlapping at least a part of an attenuation band of the attenuation band filter; An extractor having:

11. 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. The band-pass filter includes an acoustic wave resonator located on the piezoelectric body on which the first acoustic wave resonator 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 band-pass filter and the band-reducing filter, and processing 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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