JP7417487B2 - Acoustic wave devices and communication equipment - Google Patents

Description

The present disclosure relates to an elastic wave device that uses elastic waves, and a communication device that includes the elastic wave device.

BACKGROUND ART Acoustic wave devices that utilize elastic waves are known (for example, Patent Documents 1 to 3 listed below). The elastic wave is, for example, a SAW (Surface Acoustic Wave) or a BAW (Bulk Acoustic Wave). It is known that nonlinear distortion such as intermodulation distortion (IMD) occurs in elastic wave devices. Note that in this disclosure, unless otherwise specified, intermodulation distortion has a broad meaning including passive intermodulation distortion (PIM). Patent Documents 1 to 3 disclose techniques for reducing even-order nonlinear distortion.

International Publication No. 2013/161881 International Publication No. 2014/133084 International Publication No. 2016/159053

Acoustic wave devices and communication devices that can reduce nonlinear distortion are awaited.

An acoustic wave device according to an aspect of the present disclosure includes a piezoelectric body, an acoustic wave element section having an excitation electrode that applies a voltage to the piezoelectric body, the acoustic wave element section, and a predetermined terminal or a reference potential. the first nonlinear distortion, which is any one of the odd-order nonlinear distortions occurring in the acoustic wave element part, has a phase of 180±40°. and a canceling section that produces nonlinear distortion with an intensity of 1.7 to 0.3 times.

In one example, the elastic wave device is a duplexer. The duplexer includes an antenna terminal, a transmission filter that filters a signal output to the antenna terminal, and a reception filter that filters a signal input from the antenna terminal, and the elastic wave element section is the transmission filter or the reception filter.

A communication device according to an aspect of the present disclosure includes the duplexer, an antenna connected to the antenna terminal, and an integrated circuit element connected to the transmission filter and the reception filter. .

According to the above configuration, nonlinear distortion can be reduced.

1(a) and 1(b) are schematic diagrams showing a configuration example and other configuration examples of the duplexer according to the embodiment, and FIG. 1(c), FIG. 1(d), and FIG. ) is a diagram showing an example of a nonlinear element included in a duplexer according to an embodiment. FIG. 2 is a plan view showing the configuration of an elastic wave resonator included in the duplexer according to the embodiment. FIG. 2 is a circuit diagram showing the configuration of a duplexer main body included in the duplexer according to the embodiment. It is a figure explaining the nonlinearity of the elastic wave element concerning an embodiment. 5(a), FIG. 5(b), FIG. 5(c), and FIG. 5(d) are diagrams illustrating nonlinearity of a capacitor as a nonlinear element according to an embodiment. FIGS. 6A and 6B are diagrams showing calculation results regarding the influence of the polarity of nonlinearity on the reduction of nonlinear distortion. FIGS. 7A and 7B are diagrams showing other calculation results regarding the influence of the polarity of nonlinearity on the reduction of nonlinear distortion. FIGS. 8A and 8B are diagrams showing the relationship between electric field strength and polarization in a ferroelectric material and an antiferroelectric material. FIGS. 9A and 9B are diagrams showing an example of the relationship between voltage and capacitance in a capacitor including a ferroelectric material and an antiferroelectric material. FIG. 10(a) is a diagram showing a connection example of two capacitors, and FIGS. 10(b) and 10(c) are diagrams explaining the characteristics of the connection example. FIG. 11(a) is a diagram showing the characteristics of one diode, FIG. 11(b) is a diagram showing a connection example of two diodes, and FIG. 11(c) is a diagram explaining the characteristics of the connection example. 11(d) and 11(e) are diagrams showing other connection examples. FIG. 3 is a diagram showing an example of the intensity of nonlinear distortion caused by various elements. 13(a), FIG. 13(b), FIG. 13(c), and FIG. 13(d) are schematic diagrams showing examples of connections between nonlinear elements and adjustment elements. FIGS. 14(a) and 14(b) are plan views showing structural examples of the duplexer according to the embodiment. FIG. 1 is a block diagram showing the configuration of a communication device including a duplexer according to an embodiment. FIG. 7 is a plan view showing another structural example of the duplexer according to the embodiment.

Embodiments according to the present disclosure will be described below with reference to the drawings. Note that the diagrams used in the following explanation are schematic. Therefore, for example, the dimensional ratios, etc. on the drawings do not necessarily match the reality.

(Outline of duplexer)
FIG. 1A is a schematic diagram showing the configuration of a duplexer 1A according to a first example. FIG. 1(b) is a schematic diagram showing the configuration of a duplexer 1B according to a second example. Hereinafter, the duplexers 1A and 1B may be referred to as the duplexer 1 without distinction. Each duplexer 1 is an example of an elastic wave device.

More specifically, the illustrated duplexer 1 is configured as a duplexer. The duplexer 1 includes, for example, a transmission filter 13 (an example of an elastic wave element section) that filters the transmission signal from the transmission terminal 7 and outputs the filtered signal to the antenna terminal 5, and a transmission filter 13 (an example of an elastic wave element section) that filters the transmission signal from the antenna terminal 5 and receives the filtered signal. It has a reception filter 15 that outputs to the terminal 9. Note that the transmission terminal 7 can be said to be an input terminal for the transmission filter 13. The antenna terminal 5 can be said to be an output terminal for the transmission filter 13.

The transmission filter 13 includes, for example, an elastic wave element 19. As a result, the transmission filter 13 generates nonlinear distortion (distortion signal) due to the nonlinearity of the elastic wave element 19. Therefore, the duplexer 1 includes a canceling section 17 for reducing nonlinear distortion. The canceling unit 17 generates a second nonlinear distortion having an opposite phase to the first nonlinear distortion generated in the transmission filter 13 (acoustic wave element unit). Thereby, at least a portion of the first nonlinear distortion is canceled out by the second nonlinear distortion.

The intensity of the second nonlinear distortion generated by the canceling section 17 is, for example, less than twice the intensity of the first nonlinear distortion generated by the transmission filter 13 (acoustic wave element section), for example, 1.7 to 0.3 times, which is ideal. Actually, it is 1 times more. If it is less than twice, the nonlinear distortion occurring in the duplexer 1 is reduced to some extent compared to an embodiment in which the canceling section 17 is not provided. If it is 1 times, all of the first nonlinear distortion output from the transmission filter 13 is canceled out.

Note that the strength is, for example, voltage, current, and/or electric power, and unless otherwise specified, it refers to an absolute value. In other words, the opposite phase means that the phases are 180° out of phase. The phase may be changed as appropriate within the range of 180±40°. Furthermore, when we say that the phases are opposite, it is assumed that the frequencies are the same. Unless otherwise specified, the phase and intensity comparison may be made between the first nonlinear distortion and the second nonlinear distortion at the same time in a situation where an AC signal is input to the transmission filter 13. Like the transmission filter 13, the reception filter 15 may be configured to include an elastic wave element 19.

In the duplexer 1A, the canceling section 17 is connected in series to the transmission filter 13 between the transmission terminal 7 and the antenna terminal 5. In other words, the canceling unit 17 mediates between the transmission filter 13 and the antenna terminal 5. Although not particularly illustrated, a canceling unit 17 that mediates between the transmitting filter 13 and the transmitting terminal 7 may be provided instead of or in addition to the canceling unit 17 that mediates between the transmitting filter 13 and the antenna terminal 5. That is, the canceling units 17 connected in series may be connected to either the input side or the output side of the transmission filter 13. Further, the canceling section 17 may be provided at a position that mediates between the reception filter 15 and the antenna terminal 5.

In the duplexer 1B, the canceling section 17 is connected to a shunt between the transmission filter 13 and the antenna terminal 5. A shunt refers to a mode in which a signal is branched off from a signal path (here, a path from the transmission filter 13 to the antenna terminal 5) and connected to the reference potential section 11. From another perspective, the cancellation unit 17 mediates between the antenna terminal 5 side of the transmission filter 13 and the reference potential unit 11. Although not particularly illustrated, instead of or in addition to the canceling section 17 that mediates between the antenna terminal 5 side of the transmission filter 13 and the reference potential section 11, the canceling section 17 mediates between the transmission terminal 7 side of the transmission filter 13 and the reference potential section 11. A canceling unit 17 may be provided. That is, the canceling section 17 connected to the shunt may be connected to either the input side or the output side of the transmission filter 13. Further, the canceling section 17 may be provided at a position that mediates between the reception filter 15 and the antenna terminal 5.

Although not particularly illustrated, the duplexers 1A and 1B may be combined. That is, the duplexer 1 may include a canceling section 17 connected in series to the transmitting filter 13 and a canceling section 17 connected to the transmitting filter 13 in a shunt manner. In addition, although the canceling section 17 connected to the transmitting filter 13 is illustrated here, it is connected to the receiving filter 15 instead of or in addition to the canceling section 17 to reduce nonlinear distortion of the receiving filter 15. A canceling unit 17 may be provided.

The portion of the duplexer 1 other than the canceling section 17 may be referred to as a duplexer main body 3. The antenna terminal 5, the transmission terminal 7, the reception terminal 9, and the reference potential section 11 may be part of the duplexer 1 or the duplexer main body 3. The reference potential part 11 is a part (conductor) to which a reference potential is applied, and more specifically, it may be a terminal to which a reference potential is applied, or a structure other than the terminal (for example, a shield). You can.

The canceling unit 17 is configured to include one or more nonlinear elements 21. The nonlinear element 21 is an electronic element whose response to input voltage is nonlinear. More specifically, for example, it is an element in which the effective value of an alternating current that flows when an alternating voltage is applied changes nonlinearly (not proportionally) to a change in the effective value of the alternating voltage. This nonlinearity only needs to appear within the range of voltages that are assumed to be input to the nonlinear element 21 in the duplexer 1, and does not need to occur in every voltage range. In the duplexer 1 being implemented, the voltage assumed to be input to the nonlinear element 21 may be specified, for example, from the specifications and/or implementation status of the duplexer 1.

FIG. 1(c) to FIG. 1(e) are diagrams showing examples of the nonlinear element 21 included in the canceling section 17.

As shown in FIG. 1C, the nonlinear element 21 may be, for example, a capacitor 23 having nonlinearity. As shown in FIG. 1(d), the nonlinear element 21 may be, for example, an inductor 25 having nonlinearity. As shown in FIG. 1(e), the nonlinear element 21 may be, for example, a diode 27 having nonlinearity. In this way, the nonlinear element 21 may take various forms. The canceling unit 17 may have only one nonlinear element 21, two or more nonlinear elements of the same type, or two or more nonlinear elements of different types. You can leave it there.

Note that in FIG. 1(d), for convenience, a symbol of an inductor having a coil 25a and a core 25b is shown instead of a typical symbol of an inductor. However, the inductor 25 may not have the core 25b.

(Acoustic wave device)
FIG. 2 schematically shows the configuration of a surface acoustic wave resonator 29 (hereinafter sometimes simply referred to as "resonator 29") as an example of the acoustic wave element 19 included in the transmission filter 13 (and/or reception filter 15). FIG. In the following description, the word resonator 29 may be replaced with the word acoustic wave element 19 unless a contradiction occurs.

Although the resonator 29 may be oriented either upward or downward, in the following, for convenience, an orthogonal coordinate system consisting of the D1 axis, D2 axis, and D3 axis is attached to the drawing, and the D3 axis is Terms such as upper surface or lower surface may be used with the positive side of the surface as the upper side. Note that the D1 axis is defined to be parallel to the propagation direction of an elastic wave propagating along the top surface of the piezoelectric body, which will be described later, and the D2 axis is defined to be parallel to the top surface of the piezoelectric body and orthogonal to the D1 axis. The D3 axis is defined to be orthogonal to the top surface of the piezoelectric body.

The resonator 29 is constituted by a so-called one-port acoustic wave resonator. For example, the resonator 29 outputs a signal input from one of the two terminals 28 schematically shown on both sides of the paper from the other of the two terminals 28. At this time, the resonator 29 converts an electric signal into an elastic wave, and converts an elastic wave into an electric signal. As will be understood from the description of FIG. 3 described later, the terminal 28 corresponds to, for example, any one of the antenna terminal 5, the transmission terminal 7, the reception terminal 9, and the reference potential section 11.

The resonator 29 includes, for example, a substrate 31 (at least a part of the upper surface 31a side thereof), an excitation electrode 33 located on the upper surface 31a, and a pair of reflectors 35 located on both sides of the excitation electrode 33. There is. A plurality of resonators 29 may be configured on one substrate 31. That is, the substrate 31 may be shared by a plurality of resonators 29. In the following description, in order to distinguish between a plurality of resonators 29 that share the same substrate 31, for convenience, the combination of an excitation electrode 33 and a pair of reflectors 35 (electrode portions of the resonator 29) will be referred to as the resonator 29. (as if the resonator 29 does not include the substrate 31).

The substrate 31 has piezoelectricity at least in the region of the upper surface 31a where the resonator 29 is provided. An example of such a substrate 31 is one in which the entire substrate is made of a piezoelectric material (that is, a piezoelectric substrate). Further, for example, a so-called bonded substrate can be mentioned. A bonded substrate is a substrate made of a piezoelectric material having an upper surface 31a (piezoelectric substrate) and a surface of the piezoelectric substrate opposite to the upper surface 31a, which is directly attached with or without an adhesive. and a mated support substrate. The support substrate may or may not have a cavity below the piezoelectric substrate. Further, as for the substrate 31 having piezoelectricity in the region where the resonator 29 is provided, for example, the support substrate and a part of the main surface on the +D3 side of the support substrate or the entire main surface are made of piezoelectric material. Examples include those in which a film (piezoelectric film) or a multilayer film including a piezoelectric film is formed.

The piezoelectric body 31b constituting at least the region of the substrate 31 where the resonator 29 is provided is made of, for example, a piezoelectric single crystal. Examples of materials constituting such a single crystal include lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), and quartz (SiO ₂ ). The cut angle, planar shape, and various dimensions may be set appropriately.

The excitation electrode 33 and the reflector 35 are composed of a layered conductor provided on the substrate 31. The excitation electrode 33 and the reflector 35 are, for example, made of the same material and thickness. The layered conductors constituting these are, for example, metal. The metal is, for example, Al or an alloy containing Al as a main component (Al alloy). The Al alloy is, for example, an Al-Cu alloy. The layered conductor may be composed of multiple metal layers. The thickness of the layered conductor is appropriately set depending on the electrical characteristics required of the resonator 29 and the like. As an example, the thickness of the layered conductor is 50 nm or more and 600 nm or less.

The excitation electrode 33 is constituted by a so-called IDT (Interdigital Transducer) electrode, and has a pair of comb-teeth electrodes 37 (one is hatched for convenience to improve visibility). Each comb-teeth electrode 37 includes, for example, a busbar 39, a plurality of electrode fingers 41 extending in parallel from the busbar 39, and a plurality of dummy electrodes 43 protruding from the busbar 39 between the plurality of electrode fingers 41. There is. The pair of comb-teeth electrodes 37 are arranged so that the plurality of electrode fingers 41 interlock with each other (cross each other).

The bus bar 39 is, for example, formed in an elongated shape that has a substantially constant width and extends linearly in the propagation direction of the elastic wave (direction D1). The pair of bus bars 39 are opposed to each other in a direction (direction D2) orthogonal to the propagation direction of elastic waves. Note that the bus bar 39 may have a width that changes or may be inclined with respect to the propagation direction of the elastic wave.

Each electrode finger 41 is, for example, formed in an elongated shape that has a substantially constant width and extends linearly in a direction (direction D2) orthogonal to the propagation direction of elastic waves. Note that the electrode fingers 41 may have varying widths. In each comb-teeth electrode 37, the plurality of electrode fingers 41 are arranged in the propagation direction of the elastic wave. Moreover, the plurality of electrode fingers 41 of one comb-teeth electrode 37 and the plurality of electrode fingers 41 of the other comb-teeth electrode 37 are basically arranged alternately.

The pitch p of the plurality of electrode fingers 41 (for example, the distance between the centers of two adjacent electrode fingers 41) is basically constant within the excitation electrode 33. Note that the excitation electrode 33 may have a part that is unique with respect to the pitch p. Specific areas include, for example, a narrow pitch area where the pitch p is narrower than the majority (for example, 80% or more), a wide pitch area where the pitch p is wider than the majority, and a small number of electrode fingers 41 that are substantially spaced apart. An example is the thinned out part.

In the following, unless otherwise specified, pitch p refers to the pitch of a portion (most of the plurality of electrode fingers 41) excluding the unique portions as described above. In addition, in cases where the pitch of most of the plurality of electrode fingers 41 excluding peculiar parts is changing, the average value of the pitches of most of the plurality of electrode fingers 41 is used as the value of pitch p. May be used.

The number of electrode fingers 41 may be appropriately set depending on the electrical characteristics required of the resonator 29 and the like. Since FIG. 2 is a schematic diagram, the number of electrode fingers 41 is shown to be small. In reality, more electrode fingers 41 than shown may be arranged. The same applies to the strip electrode 47 of the reflector 35, which will be described later.

The lengths of the plurality of electrode fingers 41 are, for example, equal to each other. Note that the excitation electrode 33 may be subjected to so-called apodization, in which the length of the plurality of electrode fingers 41 (from another point of view, the intersection width W) changes depending on the position in the propagation direction. The length and width of the electrode fingers 41 may be set as appropriate depending on required electrical characteristics and the like.

The dummy electrode 43 has, for example, a substantially constant width and protrudes in a direction perpendicular to the propagation direction of the elastic wave. Its width is, for example, equivalent to the width of the electrode finger 41. Further, the plurality of dummy electrodes 43 are arranged at the same pitch as the plurality of electrode fingers 41, and the tip of the dummy electrode 43 of one comb-teeth electrode 37 is the tip of the electrode finger 41 of the other comb-teeth electrode 37. and are facing each other through a gap. Note that the excitation electrode 33 may not include the dummy electrode 43.

The pair of reflectors 35 are located on both sides of the excitation electrode 33 in the propagation direction of the elastic wave. For example, each reflector 35 may be electrically floating or may be provided with a reference potential. Each reflector 35 is formed, for example, in a lattice shape. That is, the reflector 35 includes a pair of bus bars 45 facing each other and a plurality of strip electrodes 47 extending between the pair of bus bars 45. The pitch between the plurality of strip electrodes 47 and the pitch between adjacent electrode fingers 41 and strip electrodes 47 are basically equivalent to the pitch between the plurality of electrode fingers 41.

When a voltage is applied to the pair of comb-teeth electrodes 37, the voltage is applied to the piezoelectric upper surface 31a by the plurality of electrode fingers 41, and the upper surface 31a vibrates. This excites an elastic wave (for example, SAW) that propagates in the D1 direction. The elastic waves are reflected by the plurality of electrode fingers 41. Then, a standing wave is created in which the pitch p of the plurality of electrode fingers 41 is approximately half a wavelength (λ/2). Electric signals generated on the substrate 31 by the standing waves are extracted by the plurality of electrode fingers 41. Based on this principle, the resonator 29 functions as a resonator whose resonant frequency is the frequency of an elastic wave whose pitch p is a half wavelength.

Although not particularly shown, the resonator 29 may have a protective film (not shown) that covers the upper surface 31a of the substrate 31 from above the excitation electrode 33 and the reflector 35. Such a protective film is made of an insulating material such as SiO ₂ , for example, and reduces the possibility that the excitation electrode 33 etc. will corrode, and/or compensates for changes in characteristics due to temperature changes of the resonator 29. Contribute to things. Furthermore, the resonator 29 may have an additional film that overlaps the upper or lower surface of the excitation electrode 33 and the reflector 35 and has a shape that basically fits within the excitation electrode 33 and the reflector 35 when seen in plan view. good. Such an additional film is made of, for example, an insulating material or a metal material that has different acoustic characteristics from the material of the excitation electrode 33, etc., and contributes to improving the reflection coefficient of the SAW.

A typical configuration example of one resonator 29 has one excitation electrode 33, as described above. However, one resonator 29 may have a plurality of excitation electrodes 33 connected in series. In other words, one resonator 29 may be divided into a plurality of parts. In this case, for example, the voltage applied to the resonator 29 is distributed to the plurality of excitation electrodes 33, so that the electric resistance of the resonator 29 is improved. Furthermore, since the vibrations of the elastic waves are reduced, nonlinear distortion is reduced.

(Example of configuration of duplexer body)
FIG. 3 is a circuit diagram schematically showing the configuration of the duplexer main body 3 (the portion of the duplexer 1 excluding the canceling section 17). As can be understood from the reference numeral shown at the upper left of the drawing, the comb-teeth electrode 37 is schematically shown in the form of a two-pronged fork, and the reflector 35 is a single line with bent ends. It is expressed as. In the following description, the term duplexer main body 3 may be replaced with the term duplexer 1 as long as there is no contradiction.

The duplexer main body 3 has the antenna terminal 5, the transmission terminal 7, the reception terminal 9, the reference potential section 11, the transmission filter 13, and the reception filter 15, as described above. In addition, in FIG. 3, two receiving terminals 9 are drawn, unlike FIG. 1. In the configuration illustrated in FIG. 3, this corresponds to the reception filter 15 outputting a balanced signal containing two signals whose phases are opposite to each other. However, the reception filter 15 may output an unbalanced signal consisting of one signal whose signal level changes with respect to the reference potential (the number of reception terminals 9 may be one). .

The transmission filter 13 is configured by, for example, a ladder type filter in which a plurality of resonators 29 (29S and 29P) are connected in a ladder type. That is, the transmission filter 13 includes a plurality of (or one) series resonators 29S connected in series between the transmission terminal 7 and the antenna terminal 5, the series line (series arm), and the reference potential section 11. It has a plurality of (or even one) parallel resonators 29P (parallel arms) that connect the two.

The reception filter 15 includes, for example, a resonator 29 and a multimode filter 49 (including a double mode filter. Hereinafter, it may be referred to as the MM filter 49). The MM filter 49 includes a plurality of (three in the illustrated example) excitation electrodes 33 arranged in the propagation direction of elastic waves, and a pair of reflectors 35 disposed on both sides of the excitation electrodes 33.

Note that the configurations of the transmission filter 13 and reception filter 15 described above are merely examples, and may be modified as appropriate. For example, the reception filter 15 may be configured by a ladder filter like the transmission filter 13, or conversely, the transmission filter 13 may include the MM filter 49.

In the above configuration, each of the plurality of resonators 29 (29S, 29P and the resonator 29 of the reception filter 15) and the MM filter 49 is an example of the elastic wave element 19. These plurality of acoustic wave elements 19 may be provided on one substrate 31 or may be provided in a distributed manner on two or more substrates 31. For example, the plurality of resonators 29 configuring the transmission filter 13 may be provided on the same substrate 31. Similarly, the resonator 29 and the MM filter 49 that constitute the reception filter 15 may be provided on the same substrate 31. The transmission filter 13 and the reception filter 15 may be provided on the same substrate 31 or may be provided on mutually different substrates 31. In addition to the above, for example, a plurality of series resonators 29S may be provided on the same substrate 31, and a plurality of parallel resonators 29P may be provided on another same substrate 31.

(Types of nonlinearity and nonlinear distortion of elastic wave elements)
FIG. 4 is a diagram illustrating the nonlinearity of the acoustic wave element 19.

In this figure, the horizontal axis indicates stress T (Pa) generated in the piezoelectric body 31b that constitutes the acoustic wave element 19. The value of stress T is larger toward the right side of the horizontal axis. The center position of the horizontal axis is the position where the stress T is zero. The vertical axis indicates the strain S of the piezoelectric body 31b (a dimensionless quantity; here, it is not a strain signal but a ratio of the amount of deformation of the piezoelectric body 31b). On the vertical axis, the higher the value, the larger the value. The center position of the vertical axis is the position where the strain S is 0.

A line L0 indicates the relationship between the stress T and the strain S when it is assumed that the piezoelectric body 31b has linear characteristics. That is, the line L0 indicates a hypothetical characteristic in which stress T and strain S are in a proportional relationship.

On the other hand, the line L1 indicates the actual characteristics of the piezoelectric body 31b. In the actual piezoelectric body 31b, when the absolute value of the stress T reaches a certain level, strain becomes less likely to occur, and furthermore, the piezoelectric body 31b becomes saturated. That is, the characteristics of the piezoelectric body 31b are nonlinear in that input and response are not proportional. In this case, it may be said that the elastic constant c that defines the relationship between stress T and strain S has nonlinearity. In addition, in piezoelectric materials, other physical properties of the material, such as the dielectric constant ε and the piezoelectric constant e, also have nonlinearity. When the dielectric constant ε has nonlinearity, the relationship between the voltage applied to the acoustic wave element 19 and the flowing current is no longer linear. Further, when the piezoelectric constant e has nonlinearity, the stress and the generated charge are not linear. In either case, the relationship between the voltage applied to the acoustic wave element 19 and the flowing current eventually becomes nonlinear.

From the above, the elastic wave element 19 has nonlinearity that causes a nonlinear response to the input voltage. Therefore, for example, when one or more signals with relatively high power are input to the elastic wave element 19, nonlinear distortion (distortion signal) occurs.

For example, the frequencies of two signals (input voltages) input to the acoustic wave element 19 are f1 and f2, and m and n are integers (...-3, -2, -1, 0, 1, 2, 3...) shall be. At this time, in the nonlinear element 21, a signal (an output voltage and an output current from another point of view) having a frequency of m×f1+n×f2 is generated. |m|+|n| is called the degree. A signal in which |m|+|n| is 2 or more is nonlinear distortion. A signal in which both m and n are not 0 has intermodulation distortion (in a broad sense). A signal in which one of m and n is 0 is a harmonic.

Various signals can be cited as the two signals that cause nonlinear distortion. For example, in a duplexer 1 that is shared by two or more frequency bands in a base station or the like, two transmission signals are simultaneously input to the transmission terminal 7. Further, examples include interference waves (noise) from the antenna terminal 5 and a transmission signal input to the transmission terminal 7. Note that in this specification, when two transmission signals are input to the transmission filter 13, intermodulation distortion generated due to third-order nonlinearity of the elastic wave element 19 becomes the reception frequency band, and the distorted signal is transmitted to the reception frequency band. What appears on the output side of the filter 15 is defined as PIM3 (3rd Order Passive Inter-Modulation), and the operating principle of the present invention will be explained.

In the description of this embodiment, for example, when the nonlinear distortion generated by the elastic wave element 19 or the transmission filter 13 is compared with the nonlinear distortion generated by the nonlinear element 21 or the canceling section 17, unless otherwise specified, It is assumed that the values of m and n are the same in both cases, and the signals that cause nonlinear distortion are the same. In other words, it is assumed that the two nonlinear distortions to be compared have the same frequency (m×f1+n×f2).

(Example of capacitor nonlinearity)
5(a) to 5(d) are diagrams illustrating the nonlinearity of the capacitor 23 used in the nonlinear element 21. FIG.

In FIGS. 5(a) and 5(b), the horizontal axis indicates the strength (V/m) of the electric field E applied between the electrodes (dielectric material) of the capacitor 23. The electric field E is stronger toward the right side of the horizontal axis. The center position of the horizontal axis is the position where the strength of the electric field E is zero. The vertical axis indicates polarization P (C/m ² ) of the dielectric between the electrodes of the capacitor 23. On the vertical axis, the higher the value, the larger the value. The center position of the vertical axis is the position where the polarization P is 0.

In FIGS. 5A and 5B, a line L10 indicates the relationship between the strength of the electric field E and the polarization P in a dielectric material having linear characteristics. That is, the line L10 shows a characteristic in which the strength of the electric field E and the polarization P are in a proportional relationship.

A line L11 in FIG. 5(a) and a line L12 in FIG. 5(b) each show an example of the relationship between the strength of the electric field E and the polarization P in a dielectric material having nonlinear characteristics. Line L11 in FIG. 5(a) shows an example of nonlinearity in which when the absolute value of the strength of electric field E increases, the absolute value of polarization P becomes smaller compared to the linear characteristic (line L10). . Such nonlinearity is referred to as negative nonlinearity. Conversely, the line L12 in FIG. 5(b) shows an example of nonlinearity in which when the absolute value of the electric field E increases, the absolute value of the polarization P increases compared to the linear characteristic (line L10). ing. Such nonlinearity is referred to as positive nonlinearity.

In FIGS. 5(c) and 5(d), the horizontal axis indicates the voltage V (unit: V) applied to the capacitor 23. The value of voltage V is larger toward the right side of the horizontal axis. The center position on the horizontal axis is the position where the voltage V is 0. The vertical axis indicates the capacitance C(F) of the capacitor 23. On the vertical axis, the higher the value, the larger the value. The center position of the vertical axis is the position where the capacitance C is 0.

In FIGS. 5(c) and 5(d), a line L15 indicates the relationship between the voltage V and the capacitance C in a capacitor in which the dielectric between the electrodes has linearity. That is, line L15 corresponds to line L10 in FIGS. 5(a) and 5(b). The capacitance C in this case is constant regardless of the voltage V.

In FIG. 5C, a line L16 indicates the relationship between the voltage V and the capacitance C in the capacitor 23 in which the dielectric between the electrodes has negative nonlinearity. That is, line L16 corresponds to line L11 in FIG. 5(a). In this case, the capacitance C becomes smaller as the absolute value of the voltage V becomes larger. This characteristic is sometimes referred to as negative nonlinearity.

In FIG. 5(d), a line L17 indicates the relationship between the voltage V and the capacitance C in the capacitor 23 in which the dielectric between the electrodes has positive nonlinearity. That is, line L17 corresponds to line L12 in FIG. 5(b). The capacitance C in this case increases as the absolute value of the voltage V increases. This characteristic is sometimes referred to as positive nonlinearity.

Capacitor 23 having such nonlinearity can cause nonlinear distortion similarly to elastic wave element 19. Therefore, by connecting the canceling section 17 including such a capacitor 23 to the elastic wave element 19 (transmission filter 13), at least a portion of the nonlinear distortion generated by the elastic wave element 19 can be canceled.

(Sign of nonlinearity)
As mentioned above, nonlinearity has positive polarity and negative polarity. According to the inventor's study, the nonlinear distortion caused by one of the positive and negative nonlinearities can be canceled out by the nonlinear distortion caused by the elastic wave element 19, while the nonlinear distortion caused by the other positive and negative nonlinearity The generated nonlinear distortion is added to the nonlinear distortion generated by the elastic wave element 19, increasing the nonlinear distortion.

6(a), FIG. 6(b), FIG. 7(a), and FIG. 7(b) show simulations of the influence of the polarity of the nonlinearity of the capacitor 23 on the effect of canceling the nonlinear distortion generated by the transmission filter 13. It is a figure showing a calculation result.

In these figures, the horizontal axis indicates the frequency f (MHz). The vertical axis indicates third-order passive intermodulation (dBm), which is abbreviated as PIM3 (dBm) in the figure. A plurality of lines in the figure indicate the relationship between the frequency f and the PIM3 for a plurality of cases in which the magnitude of the nonlinearity of the capacitance of the capacitor 23 is made different from each other. The numerical values in the legend at the bottom of the drawing indicate the nonlinear capacitance C ₃ (F/V ² ) of the case to which each line corresponds. Nonlinear capacitance is expressed by the following formula
C=C ₁ +C ₁ V+C ₃ V ² +...

6(a) and 6(b) show the results when the capacitor 23 is connected in series with the transmission filter 13 as in FIG. 1(a). 7(a) and 7(b) show the results when the capacitor 23 is connected in a shunt manner to the transmission filter 13 as shown in FIG. 1(b). 6(a) and 7(a) show the results when the capacitor 23 has positive nonlinearity. FIGS. 6(b) and 7(b) show the results when the capacitor 23 has negative nonlinearity. Note that other elements (described later) that adjust the intensity and/or phase of nonlinear distortion produced by the capacitor 23 are not connected here. Furthermore, in order to simplify the calculation, the primary and secondary capacitances C ₁ and C ₂ are set to 0. That is, it is assumed that the capacitor 23 has only third-order nonlinearity _C3 .

In these figures, the line where the nonlinear capacitance C ₃ is 0 shows the results of an embodiment (comparative example) in which the capacitor 23 is not connected. When the polarity of the nonlinearity of the capacitor 23 is positive (FIGS. 6(a) and 7(a)), the nonlinear capacitance of the capacitor 23 is The larger _C3 is, the more PIM3 is reduced. However, this does not apply if the nonlinear capacitance _C3 of the capacitor 23 is made too large. On the other hand, when the polarity of the nonlinearity of the capacitor 23 is negative (FIGS. 6(b) and 7(b)), the nonlinear capacitance of the capacitor 23 is As _C3 increases, PIM3 increases.

As confirmed by the above calculation results, the nonlinear distortion caused by the acoustic wave element 19 can be reduced by appropriately setting the sign of the nonlinearity in the nonlinear element 21. In other words, even if there is a known document that simply discloses the acoustic wave element 19 and the nonlinear element 21, if the positive or negative of the nonlinearity is not taken into account, the technology according to the present embodiment is disclosed. Must not be.

In addition, in the configuration used as the condition for the above-mentioned simulation calculation, positive nonlinearity had the effect of reducing nonlinear distortion. However, depending on the configuration of the elastic wave element 19 and/or the elastic wave element section (transmission filter 13 in this embodiment) constituted by the elastic wave element 19, negative nonlinearity may cause nonlinear distortion, contrary to the above. This can have the effect of reducing Furthermore, as will be described later, the phase and/or intensity of nonlinear distortion etc. can be adjusted by connecting other elements in series or parallel to the nonlinear element 21, so depending on the adjustment, the above simulation calculation A capacitor 23 with increased nonlinear distortion is also available.

(Example of capacitor configuration)
The structure of the capacitor 23 may be any suitable structure. For example, the capacitor 23 may have two layered electrodes facing each other with a dielectric material (dielectric layer) sandwiched therebetween in the thickness direction. In this case, the dielectric and the electrode may be planar or curved. Further, the capacitor 23 may be provided on the surface of the dielectric material or embedded in the dielectric material, and may have two layered electrodes facing each other in the planar direction (direction perpendicular to the thickness direction). In this case, the electrodes may be elongated, extending parallel to each other, or may be comb-shaped electrodes that engage with each other. Furthermore, the capacitor 23 may be configured as an electronic component mounted on a circuit board, or may be built into the circuit board.

By using a nonlinear dielectric material for the capacitor 23, the capacitor 23 having nonlinearity can be realized. Various types of dielectric materials can be used as such dielectric materials. For example, paraelectric materials generally have linearity, but some materials can exhibit nonlinearity as shown in FIG. 5(a) or FIG. 5(b). In addition, examples of dielectrics having large nonlinearity include ferroelectrics and antiferroelectrics.

The specific components and/or compositions of the ferroelectric and antiferroelectric may be determined as appropriate. For example, the ferroelectric material may be based on barium titanate (BaTiO ₃ ). Further, for example, the antiferroelectric material may be based on lead zirconate titanate (PZT) or lead lanthanum zirconate titanate (PLZT). Note that the BaTiO ₃ system may include not only BaTiO ₃ but also BaTiO ₃ in which a relatively small amount (molar ratio) of BaTiO 3 is partially substituted with other elements, and/or the composition formula: may contain impurities that are not incorporated into the The same applies to PZT and PLZT. In this case, the molar ratio of substitution may be, for example, 0.2 or less, 0.1 or less, or 0.01 or less within each site. And/or the mass % of impurities may be, for example, 20 mass % or less, 10 mass % or less, or 1 mass % or less.

(Example of nonlinearity of ferroelectric capacitor and antiferroelectric capacitor)
FIG. 8(a) is a diagram showing the relationship between the strength of the electric field E and the polarization P in a ferroelectric material. FIG. 8(b) is a diagram showing the relationship between the strength of the electric field E and the polarization P in an antiferroelectric material. The horizontal and vertical axes of these figures are the same as those of FIGS. 5(a) and 5(b).

As shown in these figures, in ferroelectrics and antiferroelectrics, the strength of the electric field E and the polarization P are not in a proportional relationship. That is, ferroelectrics and antiferroelectrics have nonlinearity. As a result, as a dielectric between electrodes (for convenience, this also includes a dielectric in which electrodes are arranged on the surface of the dielectric. The same applies in other descriptions unless there is a contradiction). The capacitor 23 having antiferroelectric material has positive and/or negative nonlinearity.

The relationship between the voltage V (for example, effective value) and the capacitance C when an AC voltage is applied to the capacitor 23 having a ferroelectric or antiferroelectric material is shown by the curves shown in FIGS. 8(a) and 8(b). It is defined depending on the specific shape of the object, etc., and is diverse. Two examples are shown below.

FIG. 9A is a diagram showing an example of the relationship between the voltage V and the capacitance C in the capacitor 23 having a ferroelectric material. The horizontal and vertical axes of this figure are the same as those of FIGS. 5(c) and 5(d). This figure was obtained by applying an alternating current voltage of a predetermined frequency. Therefore, the voltage V on the horizontal axis is, for example, a representative value (for example, an effective value or a maximum value) of the AC voltage.

A line L21 shows the relationship between the voltage V and the capacitance C in the capacitor 23 having a ferroelectric material. In this example, as the voltage V increases from around 0, the capacitance C increases. However, as the voltage V increases, the rate of change decreases. Then, the increase in capacitance C reaches a ceiling, and furthermore, capacitance C decreases.

The capacitor 23 having such characteristics has positive nonlinearity when the voltage V is within the predetermined voltage range R1, as can be understood from a comparison with the line L22 showing linear characteristics. . Therefore, by adjusting the configuration of the capacitor 23 (for example, the thickness of the dielectric material) or connecting other elements to divide the voltage so that the voltage input to the capacitor 23 is within the voltage range R1, Capacitor 23 can be used as nonlinear element 21 having positive nonlinearity.

Furthermore, as can be understood from a comparison with line L23 showing linear characteristics, capacitor 23 has negative nonlinearity when voltage V is within a predetermined voltage range R2. Therefore, by adjusting the configuration of the capacitor 23 or connecting other elements to divide the voltage so that the voltage input to the capacitor 23 is within the voltage range R2, the capacitor 23 can be made to have negative nonlinearity. It can be used as the nonlinear element 21 having the following structure.

FIG. 9(b) is a diagram showing an example of the relationship between the voltage V and the capacitance C in the capacitor 23 having an antiferroelectric material. The horizontal and vertical axes of this figure are the same as those of FIG. 9(a). This figure is obtained by applying an alternating current voltage of the same frequency as in FIG. 9(a).

A line L25 shows the relationship between the voltage V and the capacitance C in the capacitor 23 having an antiferroelectric material. In this example, as the voltage V increases from around 0, the capacitance C increases. Further, as the voltage V increases, the rate of change increases. As the voltage V further increases, the rate of change begins to decrease. Then, the increase in capacitance C reaches a ceiling, and furthermore, capacitance C decreases.

The capacitor 23 having such characteristics has positive nonlinearity when the voltage V is within the predetermined voltage range R3, as can be understood from a comparison with the line L26 showing linear characteristics. . Therefore, by adjusting the configuration of the capacitor 23 or dividing the voltage by connecting other elements so that the voltage input to the capacitor 23 is within the voltage range R1, the capacitor 23 can be made to have positive nonlinearity. It can be used as the nonlinear element 21 having the following structure.

Furthermore, as can be understood from a comparison with line L27 showing linear characteristics, capacitor 23 has negative nonlinearity when voltage V is within a predetermined voltage range R4. Therefore, by adjusting the configuration of the capacitor 23 or connecting other elements to divide the voltage so that the voltage input to the capacitor 23 is within the voltage range R4, the capacitor 23 can be made to have negative nonlinearity. It can be used as the nonlinear element 21 having the following structure.

(Example of connection between capacitors)
The canceling unit 17 may include two or more capacitors 23 that are connected to each other. An example is shown below.

FIG. 10A is a schematic diagram showing an example of how the capacitors 23 are connected to each other.

The canceling section 17 has two capacitors 23 (23A and 23B). Each capacitor 23 has a pair of electrodes 23a and a dielectric 23b interposed therebetween. The dielectric material 23b is made of, for example, a ferroelectric material, and is polarized in advance. The direction of polarization is the direction in which the pair of electrodes 23a face each other, as indicated by the arrows in the dielectric 23b. The two capacitors 23 are connected in parallel so that the polarization directions with respect to the voltage application direction are opposite to each other. For example, the two capacitors 23 have the same configuration (have the same characteristics). However, the two capacitors 23 may have mutually different configurations (they may have mutually different characteristics).

FIG. 10(b) is a diagram showing an example of the characteristics of the two capacitors 23. In these figures, the vertical and horizontal axes are the same as in FIG. 5(d). Line L31 shows the characteristics of one of the two capacitors 23. Line L32 shows the characteristics of the other of the two capacitors 23.

Since the directions in which voltages are applied to the two capacitors 23 are opposite to each other, their characteristics are symmetrical with respect to the vertical axis passing through the position where the voltage V is zero. For example, the characteristic shown by the line L31 shows linearity when the voltage V is negative, and shows positive nonlinearity when the voltage V is positive. On the other hand, the characteristic shown by the line L32, contrary to the above, shows linearity when the voltage V is positive, and shows positive nonlinearity when the voltage V is negative.

FIG. 10(c) is a diagram showing an example of the overall characteristics of the two capacitors 23. In these figures, the vertical and horizontal axes are the same as in FIG. 5(d). A line L33 indicates the overall characteristics of the two capacitors 23.

The overall characteristics of the two capacitors 23 are the sum of the characteristics of each capacitor 23 shown in FIG. 10(b). As a result, positive nonlinearity appears across the two capacitors 23 both when the voltage V is negative and when the voltage V is positive. Note that although the capacitor 23 is an example of the nonlinear element 21, the entirety of two or more capacitors 23 connected in parallel may be regarded as the nonlinear element 21. By connecting two capacitors in this manner, even-order nonlinearity occurring in the capacitors can be eliminated. Therefore, it is possible to suppress the generation of PIM2 and second harmonics that occur as a side effect when canceling PIM3.

(inductor)
Inductor 25, like capacitor 23, may have nonlinearity. For example, in FIGS. 5(a) and 5(b), the electric field strength (V/m) on the horizontal axis is replaced with the magnetic field strength (A/m), and the polarization (C/m2 ⁾ on the vertical axis. ) may be replaced with the magnetic flux density (T), and the graph may be interpreted as a diagram showing the relationship between the strength of the magnetic field and the magnetic flux density in the core 25b (magnetic material) of the inductor 25. Furthermore, FIGS. 5(c) and 5(d) can be viewed as diagrams showing the relationship between the voltage (V) and inductance in the inductor 25 by replacing the capacitance (F) on the vertical axis with inductance (H). good. Similarly to the nonlinear capacitor 23, the nonlinear inductor 25 can produce nonlinear distortion that cancels out at least a portion of the nonlinear distortion produced by the acoustic wave element 19.

As can be understood from the fact that FIGS. 5A to 5D may be converted into diagrams showing the characteristics of the inductor 25, the inductor 25 also has positive nonlinearity and negative nonlinearity. For example, by appropriately setting the positive and negative polarity of the nonlinearity in the inductor 25, the nonlinear distortion generated in the acoustic wave element 19 can be reduced.

The inductor 25 may have an appropriate configuration. For example, the coil 25a (magnetic material) of the inductor 25 may be a wire wound three-dimensionally, or a wire or a layered conductor extending spirally or meanderingly on a plane. Good too. Further, the core 25b of the inductor 25 may or may not be provided. The core 25b may be located inside the three-dimensional coil 25a, or inside the planar and spiral coil 25a, for example. When a planar coil is provided on the surface of a magnetic body, this magnetic body may also be regarded as a type of core 25b.

The inductor 25 can realize nonlinearity by having a magnetic material having nonlinearity as the core 25b, for example. Various kinds of magnetic materials can be used as such magnetic materials. For example, paramagnetic materials generally have linearity, but some materials can exhibit nonlinearity. Further, examples of magnetic substances having large nonlinearity include ferromagnetic substances and antiferromagnetic substances. Examples of the ferromagnetic material include ferrite. Examples of the antiferromagnetic material include manganese oxide (MnO)-based and nickel oxide (NiO)-based materials.

Ferromagnets and antiferromagnets have properties similar to ferroelectrics and antiferroelectrics. For example, in FIGS. 8(a) and 8(b), the electric field strength (V/m) on the horizontal axis is replaced with the magnetic field strength (A/m), and the polarization (C/m ² ) may be replaced with magnetic flux density (T), and it may be interpreted as a diagram showing the characteristics of ferromagnets and antiferromagnets. 9(a) and 9(b) can be understood as diagrams showing the relationship between the voltage (V) and inductance in the inductor 25 by replacing the capacitance (F) on the vertical axis with inductance (H). good. Therefore, similarly to the capacitor 23 having a ferroelectric material or an antiferroelectric material, the inductor 25 is configured such that the voltage input to the inductor 25 having a ferromagnetic material or an antiferromagnetic material is within a predetermined voltage range. The inductor 25 can be used as the nonlinear element 21 having positive or negative nonlinearity by adjusting the number of turns of the coil 25a (for example, the number of turns of the coil 25a) or by connecting other elements to divide the voltage.

The canceling section 17 may include a plurality of inductors 25 connected to each other. Although not particularly shown, the canceling unit 17 is composed of two inductors connected in parallel so that the polarization directions of the magnetic bodies with respect to the right-handed screw direction of the coil 25a are opposite to each other, similar to the capacitor 23 in FIG. 10(a). 25.

(diode)
FIG. 11A is a diagram showing the characteristics of the diode 27 as the nonlinear element 21.

In this figure, the horizontal axis indicates voltage V (V). The vertical axis indicates current I(A). Line L41 shows the relationship between the voltage applied to diode 27 and the current flowing through diode 27.

As is well known, the diode 27 allows current to flow when a voltage is applied in the forward direction (in the positive range of the voltage V in the figure). On the other hand, the diode 27 ideally does not allow current to flow when a voltage is applied in the reverse direction (in the negative range of the voltage V in the figure). In addition, when a voltage is applied to the diode 27 in the forward direction, when the voltage is less than a predetermined magnitude (forward voltage or forward voltage drop), it is difficult for the current to flow, and when the voltage exceeds the forward voltage, the current flows. It will flow easier. Therefore, as can be understood from a comparison with the linear characteristic shown by line L40, diode 27 exhibits significant positive nonlinearity near the forward voltage. The diode 27 having such nonlinearity can produce nonlinear distortion that cancels out at least part of the nonlinear distortion produced by the acoustic wave element 19.

The diode 27 may have any suitable configuration. For example, the diode 27 may or may not be a semiconductor diode. Further, for example, the diode 27 may be a PN diode, a PIN diode, or a Schottky barrier diode (SBD).

The canceling unit 17 may include a plurality of diodes 27 connected to each other. An example is shown below.

FIG. 11(b) is a schematic diagram showing an example of how the diodes 27 are connected to each other.

As can be seen from FIG. 11(a), diodes generally have large even-order nonlinearity. Therefore, when suppressing odd-order distortion such as PIM3 according to the present invention, large even-order distortion (second-order intermodulation distortion, second-order harmonics, etc.) is generated from the diode due to this even-order nonlinearity. Put it away. However, by connecting two diodes, this even-order nonlinearity can be eliminated. The two diodes 27 (27A and 27B) included in the canceling unit 17 are connected in parallel in opposite directions. That is, the cathode of the diode 27A and the anode of the diode 27B are connected, and the anode of the diode 27A and the cathode of the diode 27B are connected. From another perspective, one diode 27 has a cathode connected to the acoustic wave element 19, and the other diode 27 has an anode connected to the acoustic wave element 19. This is because two diodes 27 connected in parallel are connected in series with the transmission filter 13 (FIG. 1(a)), and two diodes 27 connected in parallel are connected in a shunt manner with respect to the transmission filter 13. The same applies to any of the modes in which the terminals are connected to (FIG. 1(b)).

FIG. 11C is a diagram showing an example of the overall characteristics of the two diodes 27. In these figures, the vertical and horizontal axes are the same as in FIG. 11(a). Line L45 shows the characteristics of the two diodes 27 as a whole.

The overall characteristics of the two diodes 27 are the sum of the characteristics of each diode 27 shown in FIG. 11(a). As a result, positive nonlinearity appears across the two diodes 27 both when the voltage V is negative and when the voltage V is positive. Note that, although the diode 27 is an example of the nonlinear element 21, the whole of two or more diodes 27 connected in parallel may be regarded as the nonlinear element 21. By connecting two diodes in this manner, it is possible to eliminate even-order nonlinearity that would occur in the case of one diode. Therefore, it is possible to suppress the generation of PIM2 and second harmonics that occur as a side effect when canceling PIM3.

FIGS. 11(d) and 11(e) are schematic diagrams showing other examples of how the diode 27 is used.

In these examples, two diodes 27 are connected in series. More specifically, in FIG. 11(d), the cathodes are connected to each other. In FIG. 11(e), the anodes are connected to each other. In addition, in both the embodiments of FIG. 11(d) and FIG. 11(e), and also in any of the embodiments of FIG. 1(a) and FIG. 1(b), similar to the embodiment of FIG. 11(b). It can be said that one diode 27 has a cathode connected to the acoustic wave element 19, and the other diode 27 has an anode connected to the acoustic wave element 19. In the embodiments of FIGS. 11(d) and 11(e), no direct current flows through the diode, but it can be operated like a nonlinear capacitor. In this case as well, nonlinearity can be exhibited both when the voltage is positive and when the voltage is negative.

(Adjustment of nonlinear distortion caused by nonlinear elements)
FIG. 12 is a diagram showing an example of the intensity of nonlinear distortion caused by various elements.

In this figure, the horizontal axis indicates the strength Pin (dBm) of the signal input to the element. The vertical axis indicates the intensity (dBm) of the third harmonic H3. The lines in the figure indicate the relationship between the signal strength Pin and the harmonic H3 strength in various nonlinear elements. Specifically, the line L50 corresponds to the acoustic wave element 19. Line L51 corresponds to inductor 25. The line L52 corresponds to a PIN diode, which is an example of the diode 27. Line L53 corresponds to SBD, which is another example of diode 27. Note that the intensity of this nonlinear distortion is just an example, and varies depending on the element values of various nonlinear elements, product form, design, etc. Of course, the magnitude of the distortion generated by the resonator 29 also varies depending on the operating principle, size, design, etc. of the resonator 29.

In this example, the distortion (L52, L53) generated by the diode is larger than the distortion (L50) generated by the acoustic wave element 19, so in order to properly cancel the distortion, it is necessary to reduce the distortion generated by the diode. Need to make small adjustments. Furthermore, since the distortion (L51) generated in the inductor 25 is smaller than the distortion (L50) generated in the acoustic wave element 19, the distortion generated in the inductor 25 must be adjusted to a large extent in order to properly cancel the distortion. There is a need.

As shown in this figure, the elastic wave element 19 and the nonlinear element 21 generate nonlinear distortions of different intensities when signals of the same intensity are input to each other. Therefore, by appropriately adjusting the intensity and/or phase of the nonlinear distortion produced by the nonlinear element 21, the nonlinear distortion produced by the elastic wave element 19 can be canceled out. In other words, even if there is a publicly known document disclosing the acoustic wave element 19 and the nonlinear element 21, the strength and/or phase of the nonlinearity must be appropriately adjusted in consideration of the positive and negative of the nonlinearity. , does not disclose the technology according to this embodiment.

In the duplexer 1 shown in FIG. 1(a) or FIG. 1(b), the nonlinear element 21 is, for example, at least one of various nonlinear distortions occurring in the transmission filter 13 (acoustic wave element section). For a certain first nonlinear distortion, a nonlinear distortion (second nonlinear distortion) is generated in which the values of m and n are the same (from another point of view, the frequencies m×f1+n×f2 are the same). The phase and/or intensity of the second nonlinear distortion is adjusted so that the phase is 180±40° and the intensity is 1.7 to 0.3 times as large as that of the first nonlinear distortion. Alternatively, the phase and/or intensity may be adjusted so that the phase is 180±28° and the intensity is 1.5 to 0.5 times, or the phase is 180±16° and the intensity is 1. The phase and/or intensity may be adjusted to be .3 to 0.7 times as large. Note that the phase may not require adjustment in some cases.

When the phase of the second nonlinear distortion is 180±40° and the intensity is 1.7 to 0.3 times the first nonlinear distortion, the first nonlinear distortion is canceled out by about 3 dB and the second nonlinear distortion. It is expected that this can be reduced by When the phase of the second nonlinear distortion is 180±28° and the intensity is 1.5 to 0.5 times the first nonlinear distortion, the first nonlinear distortion is canceled out by about 6 dB and the second nonlinear distortion. It is expected that this can be reduced by When the phase of the second nonlinear distortion is 180±16° and the intensity is 1.3 to 0.7 times the first nonlinear distortion, the first nonlinear distortion is canceled by about 10 dB with the second nonlinear distortion. It is expected that this can be reduced by When the phase of the second nonlinear distortion is 180° and the intensity is 1 times that of the first nonlinear distortion, it is expected that the distortion can be almost completely canceled out.

Adjustment of the intensity and/or phase of the nonlinear distortion in the canceling unit 17 may be realized by various methods.

For example, the characteristics of the nonlinear element 21 itself may be adjusted. For example, the thickness, electrode area, and/or dielectric constant of the dielectric in the capacitor 23 are adjusted, thereby adjusting the intensity of nonlinear distortion caused by the capacitor 23, and in turn, adjusting the intensity of nonlinear distortion in the canceling section 17. It's fine. Further, for example, the number of turns, various dimensions, and/or magnetic permeability in the inductor 25 are adjusted, thereby adjusting the intensity of nonlinear distortion generated in the inductor 25, and in turn, adjusting the intensity of nonlinear distortion in the canceling section 17. It's fine. Further, for example, various dimensions in the diode 27 may be adjusted, thereby adjusting the intensity of nonlinear distortion generated by the diode 27, and, in turn, adjusting the intensity of nonlinear distortion in the canceling section 17. Further, a plurality of nonlinear elements 21 may be connected in series or in parallel.

The above-mentioned adjustment of the characteristics of the nonlinear element 21 itself may be performed in a mode in which the canceling section 17 consists of only one nonlinear element 21, or, as described below, the canceling section 17 consists of an element other than one nonlinear element 21. It may be done in an embodiment having the following. In the former mode, one nonlinear element 21 produces, for example, a second nonlinear distortion of the same frequency (m×f1+n×f2) as the first nonlinear distortion produced by the transmission filter 13 (acoustic wave element section), and this The second nonlinear distortion has a phase of 180±40° and an intensity of 1.7 to 0.3 times (or a phase of 180±28° and an intensity of 1.5 to 0.3 times) the first nonlinear distortion. 0.5 times, the phase is 180±16°, and the intensity is 1.3 to 0.7 times. Ideally, the angle is 180° and the intensity is 1 times).

Further, the intensity and/or phase of the nonlinear distortion in the canceling section 17 may be adjusted by providing one or more elements (referred to as adjustment elements 51) different from the nonlinear element 21. From another perspective, this is due to the difference in strength between the first nonlinear distortion generated in the transmission filter 13 (acoustic wave element section) and the second nonlinear distortion generated in the canceling section 17, and the phase of the first nonlinear distortion. This means that at least one of the differences between the second nonlinear distortion and the opposite phase of the second nonlinear distortion is smaller than the one difference when it is assumed that one or more adjustment elements 51 are not provided.

The adjustment element 51 may adjust the second nonlinear distortion by adjusting the signal input to the nonlinear element 21, or may directly adjust the nonlinear distortion output from the nonlinear element 21. You can. Moreover, the adjustment element 51 may be a linear element or a nonlinear element. Various elements may be used as the adjustment element 51, such as resistors, capacitors, and inductors.

When the adjustment element 51 is a nonlinear element, this nonlinear element may or may not be another nonlinear element 21 that produces nonlinear distortion that cancels the nonlinear distortion produced by the acoustic wave element 19. In the former case, from another perspective, the canceling unit 17 uses a plurality of filters that generate second nonlinear distortions at the same frequencies (m×f1 and n×f2) as the first nonlinear distortions generated by the transmission filter 13 (acoustic wave element unit). It includes a nonlinear element 21. The sum of the second nonlinear distortions generated by the plurality of nonlinear elements 21 has a phase of 180±40°, an intensity of 1.7 to 0.3 times, and a phase of 180±40° relative to the first nonlinear distortion. 28° and the intensity is 1.5 to 0.5 times, the phase is 180±16° and the intensity is 1.3 to 0.7 times.

As described above, the elastic wave element 19 has frequencies of m×f1 and n×f2, and can generate various nonlinear distortions in which the values of m and n are different from each other. This also applies to the nonlinear element 21. The canceling unit 17 may reduce only one of the various nonlinear distortions that occur in the transmission filter 13 (acoustic wave element unit) as a result of the above-mentioned adjustment, or may reduce two or more nonlinear distortions. good. For example, the canceling unit 17 may reduce only the third-order intermodulation distortion where m = 2 and n = -1, or in addition to this, the canceling unit 17 may reduce only the third-order intermodulation distortion where m = 2 and n = 1. may be reduced, and other odd-order nonlinear distortion and/or even-order nonlinear distortion may be further reduced.

FIGS. 13(a) to 13(d) are schematic diagrams showing connection examples of the adjustment element 51.

13(a) and 13(b) show an example of how the adjustment element 51 is connected in a mode in which the canceling section 17 is connected in series to the transmission filter 13. In FIG. 13(a), the nonlinear element 21 and the adjustment element 51 are connected in series. In FIG. 13(b), the nonlinear element 21 and the adjustment element 51 are connected in parallel.

13(c) and 13(d) show examples of connections of the adjustment element 51 in a mode in which the canceling section 17 is connected to the transmission filter 13 in a shunt manner. In FIG. 13(c), the nonlinear element 21 and the adjustment element 51 are connected in series. In FIG. 13(d), the nonlinear element 21 and the adjustment element 51 are connected in parallel.

Note that, unlike the illustrated example, the number of nonlinear elements 21 and/or adjustment elements 51 is not limited to one, and may be two or more. Moreover, in one or more nonlinear elements 21 and one or more adjustment elements 51, series connection and parallel connection may be combined.

In an embodiment in which the adjustment element 51 is connected in series with the nonlinear element 21, the voltage applied to the nonlinear element 21 can be reduced by voltage division, for example. Furthermore, in a mode in which the adjustment element 51 is connected in parallel with the nonlinear element 21, the current flowing through the nonlinear element 21 can be reduced by, for example, shunting. By reducing the voltage and/or current in the nonlinear element 21, the intensity of the nonlinear distortion occurring in the nonlinear element 21 can be reduced and balanced with the nonlinear distortion occurring in the transmission filter 13.

In a mode in which the adjustment element 51 is connected in series to the nonlinear element 21, a phase shifter that shifts the phase of an input signal and outputs the signal may be used as the adjustment element 51. In this case, by adjusting the phase of the signal input to the nonlinear element 21 and/or by directly adjusting the phase of the nonlinear distortion output from the nonlinear element 21, the transmission filter 13 adjusts the phase of the nonlinear distortion generated. and the phase of the nonlinear distortion output from the canceling unit 17 can be made to be in opposite phase. The phase shifter may advance or delay the phase of the input signal. The deviation of the output relative to the input in the phase shifter may be a typical value such as 90° or 180°. The configuration of the phase shifter may be similar to various known configurations.

(Other uses of adjustment element)
In addition to or instead of adjusting the intensity and/or phase of the nonlinear distortion generated by the nonlinear element 21, the adjustment element 51 adjusts the signal that should be originally transmitted (here, the transmission signal transmitted from the transmission terminal 7 to the antenna terminal 5). ) may contribute to reducing the influence of the nonlinear element 21 on the nonlinear element 21.

For example, the one or more adjustment elements 51 (FIG. 13(c)) connected in series with the one or more nonlinear elements 21 connected in a shunt manner to the transmission filter 13 are resistors with relatively large resistance values, inductances, etc. It may be an inductor with a relatively large capacity and/or a capacitor with a relatively small capacity. In this case, it is possible to make it difficult for the transmission signal to flow to the reference potential section 11.

Further, for example, one or more adjustment elements 51 (FIG. 13(b)) connected in parallel to one or more nonlinear elements 21 connected in series to the transmission filter 13 are resistors with a relatively small resistance value. , a capacitor with a relatively large capacitance, and/or an inductor with a relatively small inductance. In this case, the transmission signal can easily flow to the antenna terminal 5.

In the above, the resistance value, inductance, and capacitance of the adjustment element 51 may be set as appropriate. For example, large resistances, large inductances and/or small capacitances can be used as impedances, given the intended frequency (e.g. passband center frequency) and voltage (e.g. maximum or rms value) of the signal to be transmitted. The converted value may be 2/3 or more or 4/5 or more of the impedance of the entire canceling section 17. Further, the value obtained by converting the large capacitance and/or small inductance into impedance may be set to 1/3 or less or 1/5 or less of the impedance of the entire canceling section 17.

(Structure example)
The structure of the duplexer 1 may be any suitable structure. Two examples are shown below.

FIG. 14(a) is a plan view showing an example of the structure of the duplexer 1.

In this example, the duplexer main body 3 and one or more (three in the illustrated example) nonlinear elements 21 are each packaged electronic components. These electronic components are mounted on a circuit board 53 and connected to each other by wiring 55 on the circuit board 53. Although not particularly illustrated, other electronic components connected to the duplexer 1 and/or electronic components not connected to the duplexer 1 may be mounted on the circuit board 53. In other words, the duplexer 1 may be a part of a printed circuit board (a printed wiring board and electronic components mounted on the printed wiring board). In this way, the nonlinear element 21 may be an external electronic component to the duplexer main body 3 instead of being packaged together with the duplexer main body 3.

FIG. 14(b) is a plan view showing another example of the structure of the duplexer 1.

In this example, the duplexer main body 3 and one or more (three in the illustrated example) nonlinear elements 21 are packaged together to form one electronic component. For example, the duplexer 1 includes a circuit board 57, on which a transmission filter 13, a reception filter 15, and one or more nonlinear elements 21 are mounted. The transmission filter 13 and the reception filter 15 may be in the form of a bare chip or a wafer level package, for example. The nonlinear element 21 may be in a packaged state or may be in an unpackaged state. The transmission filter 13, the reception filter 15, and one or more nonlinear elements 21 are sealed together with a resin (not shown) that covers the upper surface of the circuit board 57. The circuit board 57 is provided with an antenna terminal 5, a transmission terminal 7, and a reception terminal 9 at appropriate positions.

The circuit boards 53 and 57 may take various known forms. For example, these substrates may be LTCC (Low Temperature Co-fired Ceramics) substrates, HTCC (High Temperature Co-Fired Ceramic) substrates, or organic substrates.

Although not particularly illustrated, the adjustment element 51 may also be an external electronic component to the duplexer main body 3, similar to the nonlinear element 21, or may be packaged together with the duplexer main body 3. good. Aspects such as whether or not to attach externally may be different between two or more nonlinear elements 21, different between two or more adjustment elements 51, or different between nonlinear element 21 and adjustment element 51. .

The structural example of FIG. 14(a) and the structural example of FIG. 14(b) may be combined. That is, some of the plurality of elements may be packaged together with the duplexer main body 3, and other elements may be attached externally. Furthermore, the nonlinear element 21 and/or the adjustment element 51 may be built into the surface and/or inside of the circuit board instead of being mounted on the circuit board 53 and/or 57.

Alternatively, as shown in FIG. 16, an element 56 in which the nonlinear element 21 and/or the adjustment element 51 are packaged together in one package may be mounted on the circuit board 53 (or 57) together with the duplexer main body 3. .

(Communication device)
FIG. 15 is a block diagram showing main parts of a communication device 151 as an example of how the duplexer 1 is used. The communication device 151 performs wireless communication using radio waves, and includes a duplexer 1, for example. Here, illustration of the canceling unit 17 is omitted.

In the communication device 151, a transmission information signal TIS containing information to be transmitted is modulated and frequency raised (converted to a high frequency signal having a carrier frequency) by an RF-IC (Radio Frequency Integrated Circuit) 153 to become a transmission signal TS. It is said that The transmission signal TS has unnecessary components outside the transmission passband removed by a bandpass filter 155, is amplified by an amplifier 157, and is input to the duplexer 1 (transmission terminal 7). Then, the duplexer 1 (transmission filter 13) removes unnecessary components other than the transmission passband from the input transmission signal TS, and outputs the removed transmission signal TS from the antenna terminal 5 to the antenna 159. . The antenna 159 converts the input electric signal (transmission signal TS) into a wireless signal (radio wave) and transmits the signal.

Furthermore, in the communication device 151, a radio signal (radio wave) received by the antenna 159 is converted into an electric signal (received signal RS) by the antenna 159, and is input to the duplexer 1 (antenna terminal 5). The duplexer 1 (reception filter 15) removes unnecessary components outside the reception passband from the input reception signal RS, and outputs the signal from the reception terminal 9 to the amplifier 161. The output reception signal RS is amplified by an amplifier 161, and a bandpass filter 163 removes unnecessary components outside the reception passband. Then, the received signal RS is frequency lowered and demodulated by the RF-IC 153 to become a received information signal RIS.

Note that the transmission information signal TIS and the reception information signal RIS may be low frequency signals (baseband signals) containing appropriate information, such as analog audio signals or digitized signals. The passband of the wireless signal may be set as appropriate, and may be a relatively high frequency passband (for example, 5 GHz or higher). The modulation method may be phase modulation, amplitude modulation, frequency modulation, or a combination of two or more of these. As for the circuit system, although a direct conversion system is illustrated in FIG. 15, any other suitable circuit system may be used, for example, a double superheterodyne system may be used. Further, FIG. 15 schematically shows only the main parts, and a low-pass filter, an isolator, etc. may be added at an appropriate position, or the position of an amplifier, etc. may be changed.

As described above, in this embodiment, the elastic wave device (brancher 1) includes an elastic wave element section (transmission filter 13) and a canceling section 17. The transmission filter 13 includes a piezoelectric body 31b and an excitation electrode 33 that applies a voltage to the piezoelectric body 31b. The cancellation unit 17 includes one or more nonlinear elements 21 that mediate between the transmission filter 13 and a predetermined terminal (the antenna terminal 5 in FIG. 1A) or the reference potential unit 11. The canceling unit 17 has a phase of 180±40° and an intensity of 1.7 to 0.3 times the first nonlinear distortion, which is any of the odd-order nonlinear distortions generated in the transmission filter 13. Causes nonlinear distortion.

Therefore, as described above, the second nonlinear distortion produced by the canceling section 17 cancels out part or all of the first nonlinear distortion produced in the elastic wave element section, and the nonlinear distortion produced in the duplexer 1 is reduced. As a result, for example, when first nonlinear distortion having a frequency within the passband of the receiving filter 15 occurs in the transmitting filter 13, the intensity of the first nonlinear distortion is reduced, and the first nonlinear distortion passes through the receiving filter 15. The probability of passing can be reduced. As a result, the receiving sensitivity of the duplexer 1 can be improved.

One or more nonlinear elements 21 may include at least one of a capacitor 23, an inductor 25, and a diode 27.

In this case, for example, the nonlinear distortion of the transmission filter 13 can be reduced using a known electronic device or an electronic device that is an application thereof. As a result, for example, cost reduction can be achieved.

The one or more nonlinear elements 21 may include a capacitor 23 whose capacitance increases as the effective value of the applied AC voltage increases within a predetermined voltage range. Furthermore, the one or more nonlinear elements 21 may include an inductor 25 whose inductance increases as the effective value of the applied AC voltage increases within a predetermined voltage range.

In these cases, the nonlinearity of capacitor 23 is positive. On the other hand, the piezoelectric body 31b exhibits negative nonlinearity, as shown in FIG. As a result, as explained with reference to FIGS. 6(a) to 7(b), the nonlinear distortion of the elastic wave element 19 can be canceled by the nonlinear distortion of the capacitor 23 without adjusting the phase. High probability. As a result, the configuration of the canceling section 17 can be simplified.

The capacitor 23 may include an antiferroelectric material (dielectric material 23b) for increasing capacitance. The antiferroelectric material may be composed of a lanthanum lead titanate zirconate based material. Further, the capacitor 23 may include a ferroelectric material (dielectric material 23b) for increasing capacitance. The ferroelectric material may be made of barium titanate-based material. The inductor 25 may include a ferromagnetic material (core 25b) for increasing inductance.

In these cases, for example, the capacitor 23 and/or the inductor 25 tend to exhibit nonlinearity, and the nonlinearity tends to become strong. Since the stronger the nonlinearity, the greater the intensity of nonlinear distortion, it is possible to obtain the effect of reducing the nonlinear distortion of the transmission filter 13 while downsizing the configuration of the nonlinear element 21.

The one or more nonlinear elements 21 include a diode 27A, which has an anode and a cathode connected to the acoustic wave element 19, and a diode 27B, which has a cathode connected to the acoustic wave element 19. That's fine.

In this case, the strong nonlinearity of the diode 27 can be utilized. Due to the strong nonlinearity, it is possible to generate nonlinear distortion for canceling the nonlinear distortion of the acoustic wave element 19 while downsizing the configuration of the nonlinear element 21. As explained with reference to FIG. 11(c), nonlinear distortion can be generated to cancel the nonlinear distortion of the acoustic wave element 19 both when the input voltage is positive and when the input voltage is negative. .

The canceling unit 17 may include one or more adjustment elements 51 connected to the nonlinear element 21. At least the difference between the intensity of the first nonlinear distortion generated by the elastic wave element 19 and the intensity of the second nonlinear distortion generated by the nonlinear element 21, and the difference between the phase of the first nonlinear distortion and the opposite phase of the phase of the second nonlinear distortion. One difference may be made smaller than the one difference when it is assumed that one or more adjustment elements 51 are not provided.

That is, the adjustment element 51 may be provided so that the second nonlinear distortion produced by the nonlinear element 21 can cancel out part or all of the first nonlinear distortion produced by the acoustic wave element 19 . In this case, for example, the degree of freedom in designing the nonlinear element 21 is improved. For example, it becomes possible to use a general-purpose product as the nonlinear element 21.

One or more adjustment elements 51 may include a nonlinear element different from nonlinear element 21.

In this case, for example, in addition to adjusting the intensity of the nonlinear distortion generated by the nonlinear element 21 by dividing the voltage or adjusting the phase of the nonlinear distortion, the nonlinear distortion generated by the adjustment element 51 is adjusted to the nonlinear distortion of the nonlinear element 21. By superimposing them, the strength of nonlinear distortion can be adjusted. As a result, for example, the degree of freedom in designing the nonlinear element 21 is improved.

One or more adjustment elements 51 may include linear elements.

In this case, the adjustment element 51 basically does not produce nonlinear distortion. Therefore, for example, it is easy to predict the influence of the adjustment element 51 on the intensity of nonlinear distortion generated by the nonlinear element 21. That is, it is easy to predict the intensity of the adjusted nonlinear distortion.

The one or more nonlinear elements 21 may be a plurality of nonlinear elements 21 that each generate second nonlinear distortion at the same frequency as the first nonlinear distortion generated by the elastic wave element 19. The sum of the second nonlinear distortions generated by the plurality of nonlinear elements 21 may have a phase of 180±40° and an intensity of 1.7 to 0.3 times the first nonlinear distortion.

In this case, for example, it is sufficient to generate second nonlinear distortion having the strength necessary to cancel part or all of the first nonlinear distortion using a plurality of nonlinear elements 21, so there is freedom in designing each nonlinear element 21. degree will improve. For example, it becomes possible to use a general-purpose product as the nonlinear element 21.

The one or more nonlinear elements 21 may include one nonlinear element 21 (for convenience, referred to as the first nonlinear element 21) that generates a second nonlinear distortion at the same frequency as the first nonlinear distortion generated by the elastic wave element 19. The second nonlinear distortion generated by the first nonlinear element 21 may have a phase of 180±40° and an intensity of 1.7 to 0.3 times as much as the first nonlinear distortion.

That is, one first nonlinear element 21 may generate second nonlinear distortion having a strength necessary to cancel part or all of the first nonlinear distortion. From another point of view, the configuration of the first nonlinear element 21 may be adjusted in this way. In this case, for example, the need to provide a plurality of nonlinear elements 21 or one or more adjustment elements 51 is reduced, and the cancellation unit 17 can be made smaller.

In addition, in the above embodiment, the duplexer 1 is an example of an elastic wave device. The transmission filter 13 is an example of an elastic wave element section. The antenna terminal 5 is an example of a predetermined terminal. RF-IC is an example of an integrated circuit device.

Further, in general, the intensity and phase of distortion generated in the elastic wave element 19 and the nonlinear element 21 have frequency dependence. Therefore, the cancellation of the first nonlinear distortion and the second nonlinear distortion is generally maximum at a certain frequency, and the cancellation effect becomes small at other frequencies. However, even in that case, it is possible to reduce distortion to some extent over a desired frequency range. This is clear from the simulation results shown in FIGS. 6 and 7. Furthermore, by optimizing the circuit using the adjustment element 51, it is possible to bring the frequency dependence of the distortion generated in the acoustic wave element 19 and the nonlinear element 21 close to each other, thereby expanding the frequency range in which the cancellation effect is exhibited. .

The technology according to the present disclosure is not limited to the above embodiments, and may be implemented in various ways.

For example, elastic waves are not limited to SAWs. The elastic waves may be BAWs, boundary acoustic waves, or plate waves (although these waves are not necessarily distinguishable from SAWs). In another aspect, the excitation electrode is not limited to an IDT. For example, the excitation electrodes may be a pair of electrodes that sandwich a piezoelectric thin film in the thickness direction, such as in a piezoelectric thin film resonator (FBAR).

The elastic wave element section is not limited to a transmission filter. For example, the elastic wave element section may be a reception filter or a resonator.

Acoustic wave devices are not limited to duplexers. For example, the elastic wave device may be a resonator or a filter. From another point of view, the elastic wave device does not need to have a functional section (the reception filter 15 in the embodiment) different from the elastic wave element section (the transmission filter 13 in the embodiment). Further, the branching filter is not limited to a duplexer. For example, the duplexer may be a triplexer with three filters or a quadplexer with four filters.

Nonlinear elements are not limited to capacitors, inductors and diodes. For example, it may be an acoustic wave element.

The technology according to the present disclosure may be used to reduce not only odd-order nonlinear distortion but also even-order nonlinear distortion. For example, inventions based on the following concepts can be extracted from the technology according to the present disclosure.

(Concept 1)
an acoustic wave element section having a piezoelectric body and an excitation electrode that applies a voltage to the piezoelectric body;
A first strain including one or more nonlinear elements mediating the elastic wave element section and a predetermined terminal or reference potential section, and which is any one of a plurality of nonlinear distortions occurring in the acoustic wave element section. a canceling section that generates nonlinear distortion with a phase of 180±40° and an intensity of 1.7 to 0.3 times with respect to nonlinear distortion;
It has
An acoustic wave device, wherein the one or more nonlinear elements include at least one of a capacitor, an inductor, and a diode.

DESCRIPTION OF SYMBOLS 1... Duplexer (acoustic wave device), 5... Antenna terminal, 11... Reference potential section, 13... Transmission filter (acoustic wave element section), 17... Cancellation section, 21... Nonlinear element, 31b... Piezoelectric body, 33... Excitation electrode.

Claims (21)

an acoustic wave element section having a piezoelectric body and an excitation electrode that applies a voltage to the piezoelectric body;
A first strain including one or more nonlinear elements mediating the elastic wave element section and a predetermined terminal or reference potential section, and which is any one of odd-order nonlinear distortions occurring in the elastic wave element section. a canceling section that generates nonlinear distortion with a phase of 180±40° and an intensity of 1.7 to 0.3 times with respect to nonlinear distortion;
An elastic wave device that has The acoustic wave device according to claim 1, wherein the one or more nonlinear elements include at least one of a capacitor, an inductor, and a diode. the one or more nonlinear elements include the capacitor;
The capacitance of the capacitor increases as the effective value of the applied AC voltage increases within a predetermined voltage range.
The elastic wave device according to claim 2. The acoustic wave device according to claim 3, wherein the capacitor includes an antiferroelectric material. The acoustic wave device according to claim 4, wherein the antiferroelectric material is made of a lead zirconate titanate-based material or a lead lanthanum zirconate titanate-based material. The acoustic wave device according to claim 3, wherein the capacitor includes a ferroelectric material. The acoustic wave device according to claim 6, wherein the ferroelectric material is made of a barium titanate-based material. the one or more nonlinear elements include the inductor,
The inductance of the inductor increases as the effective value of the applied AC voltage increases within a predetermined voltage range.
The elastic wave device according to claim 2. The acoustic wave device according to claim 8, wherein the inductor includes a ferromagnetic material. The one or more nonlinear elements are
a first diode having an anode of an anode and a cathode connected to the acoustic wave element section ;
The acoustic wave device according to claim 2, further comprising a second diode whose cathode, out of an anode and a cathode, is connected to the acoustic wave element section . The one or more nonlinear elements are
3. The acoustic wave device according to claim 2, comprising two diodes connected in series with opposite polarities. The one or more nonlinear elements include a first nonlinear element that produces a second nonlinear distortion at the same frequency as the first nonlinear distortion,
The canceling section has one or more adjustment elements connected to the first nonlinear element,
At least one of the difference between the intensity of the first nonlinear distortion and the intensity of the second nonlinear distortion, and the difference between the phase of the first nonlinear distortion and the opposite phase of the phase of the second nonlinear distortion, The elastic wave device according to any one of claims 1 to 11, wherein the difference is smaller than the one difference when the above adjustment element is not provided. The acoustic wave device according to claim 12, wherein the one or more adjustment elements include a nonlinear element different from the first nonlinear element. The acoustic wave device according to claim 12 or 13, wherein the one or more adjustment elements include a linear element. The one or more nonlinear elements are a plurality of nonlinear elements that each produce a second nonlinear distortion at the same frequency as the first nonlinear distortion, and the sum of the second nonlinear distortions produced by the plurality of nonlinear elements is equal to the first nonlinear distortion. The elastic wave device according to any one of claims 1 to 14, wherein the phase is 180±40° and the intensity is 1.7 to 0.3 times as large as nonlinear distortion. The one or more nonlinear elements include a first nonlinear element that produces a second nonlinear distortion at the same frequency as the first nonlinear distortion, and the second nonlinear distortion produced by the first nonlinear element is equal to the first nonlinear distortion. The elastic wave device according to any one of claims 1 to 15, wherein the phase is 180±40° and the intensity is 1.7 to 0.3 times as large as the distortion. The canceling unit applies nonlinear distortion with a phase of 180±40° and an intensity of 1.7 to 0.3 times for each of two or more nonlinear distortions having different frequencies that occur in the elastic wave element unit. The acoustic wave device according to any one of claims 1 to 16. The acoustic wave device according to any one of claims 1 to 17, wherein the cancellation section and the acoustic wave element section are housed in a single package. The acoustic wave device according to claim 1, wherein the cancellation section and the acoustic wave element section are mounted on a single circuit board. antenna terminal and
a transmission filter that filters a signal output to the antenna terminal;
a reception filter that filters a signal input from the antenna terminal;
It has
The elastic wave device according to any one of claims 1 to 19, wherein the elastic wave element section is the transmission filter or the reception filter. The elastic wave device according to claim 20,
an antenna connected to the antenna terminal;
an integrated circuit element connected to the transmit filter and the receive filter;
A communication device that has

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