Surface acoustic wave transducer and device comprising same

Abstract

The invention relates to a surface acoustic wave transducer and an apparatus including the same. The surface acoustic wave transducer comprises a piezoelectric layer; the interdigital electrode is arranged on the surface of the piezoelectric layer and comprises a first bus bar, a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar; the interdigital electrode comprises at least one envelope unit, the envelope unit is provided with a first envelope line defined by the ends of a plurality of first electrode fingers and a second envelope line defined by the ends of a plurality of second electrode fingers, and the first envelope line and the second envelope line are both step traces. At least two trace points in the first envelope line and corresponding trace points in the second envelope line are in central symmetry about the same point.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of semiconductors, and in particular, to a surface acoustic wave transducer and a device comprising the same. Background Art

[0002] As communication technology develops from 2G to 5G, the number of communication frequency bands has gradually increased (from 4 frequency bands in 2G to more than 50 frequency bands in 5G). In order to improve the compatibility of smartphones with different communication standards, the amount of filters required for 5G smartphones will increase significantly, driving large-scale growth in the filter market. The RF filter currently widely used in wireless communication terminals is the surface acoustic wave filter, which is responsible for filtering the RF signals of the receiving and transmitting channels and outputting signals of specific frequencies from the multiple input RF signals. In the structure of the surface acoustic wave filter, the most important unit is the resonator, so different resonator structures will have a huge impact on the final performance of the surface acoustic wave filter.

[0003] Figure 1 is a schematic diagram of the structure of the current resonator. Figure 1 As shown, the resonator includes interdigitated electrodes and reflectors 31 located on both sides of the interdigitated electrodes. The interdigitated electrodes include a first bus bar 11 and a second bus bar 21. A plurality of first electrode fingers 12 and a plurality of first virtual fingers 13 are alternately arranged on the first bus bar 11. A plurality of second electrode fingers 22 and a plurality of second virtual fingers 23 are alternately arranged on the second bus bar 21. In the propagation direction of the surface acoustic wave (i.e., the horizontal direction in the figure), the plurality of first electrode fingers 12 and the plurality of second electrode fingers 22 are arranged in an alternating manner. The first electrode fingers 12 and the second virtual fingers 23 are arranged opposite to each other and there is a gap. The second electrode fingers 22 and the first virtual fingers 13 are arranged opposite to each other and there is a gap. The connecting line of the ends of all the first electrode fingers 12 (or the connecting line of the gaps at the ends of all the first electrode fingers 12) and the connecting line of the ends of all the second electrode fingers 22 (or the connecting line of the gaps at the ends of all the second electrode fingers 22) are all straight lines along the propagation direction of the surface acoustic wave. Figure 1 The resonator shown has the problem of lateral energy leakage of acoustic waves, which will cause energy loss in the filter and reduce the filter performance. Summary of the invention

[0004] The present disclosure is proposed to alleviate or solve at least one aspect of the above-mentioned problems in the prior art.

[0005] According to one aspect of an embodiment of the present disclosure, a surface acoustic wave transducer is proposed, comprising: a piezoelectric layer; an interdigitated electrode, arranged on the surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar; the interdigitated electrode comprises at least one envelope unit, the envelope unit having a first envelope defined by ends of the plurality of first electrode fingers and a second envelope defined by ends of the plurality of second electrode fingers, the first envelope and the second envelope are both step traces, and at least two trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point center.

[0006] According to one aspect of an embodiment of the present disclosure, a surface acoustic wave transducer is provided, comprising: a piezoelectric layer; an interdigitated electrode, arranged on the surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar; the interdigitated electrode comprises at least one envelope unit, the envelope unit having a first envelope defined by ends of the plurality of first electrode fingers and a second envelope defined by ends of the plurality of second electrode fingers, the first envelope and the second envelope being both step traces, at least two trace points in the first envelope and corresponding trace points in the second envelope being symmetrical about the same point center; the minimum aperture in the finger aperture of the envelope unit is 4.75 times to 34.75 times the wavelength of the surface acoustic wave transducer, and / or the maximum aperture in the finger aperture of the envelope unit is 10.25 times to 40.25 times the wavelength of the surface acoustic wave transducer.

[0007] According to one aspect of an embodiment of the present disclosure, a device is provided, comprising the above-mentioned surface acoustic wave transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed in the present disclosure, wherein the same reference numerals in the drawings always represent the same components, wherein:

[0009] Figure 1 is a schematic top view of a known resonator;

[0010] Figure 2 is a schematic top view of a surface acoustic wave transducer according to an exemplary embodiment of the present disclosure;

[0011] Figure 3 Shows Figure 2 Traces and symmetry center of the SAW transducer;

[0012] Figure 4 for Figure 2 A schematic cross-sectional view of a surface acoustic wave transducer;

[0013] Figure 5 for Figure 2 A schematic diagram of the interdigitated electrode portion of a surface acoustic wave transducer, showing various dimensions;

[0014] Figure 6 The comparison chart of the test results shows the Figure 1 and Figure 2 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency;

[0015] Figure 7 The comparison chart of the test results shows Figure 1 and Figure 2 The quality factor of the surface acoustic wave transducer changes with frequency;

[0016] Figure 8 and Fig. 9 for Figure 2 Variations of the SAW transducer;

[0017] Fig.10 A structural comparison diagram of a local central symmetric scheme and a non-central symmetric scheme is shown;

[0018] Fig.11 A comparison chart of the test results of the local central symmetry scheme and the non-central symmetry scheme is shown.

[0019] The following are the descriptions of the reference numerals:

[0020] 11: first bus bar;

[0021] 12: first electrode finger;

[0022] 13: First virtual finger;

[0023] 14: first trace;

[0024] 21: Second bus bar;

[0025] 22: second electrode finger;

[0026] 23: The second virtual finger;

[0027] 24: second trace;

[0028] 31: reflector;

[0029] 50: symmetry center;

[0030] 51-54: trace points;

[0031] 100: silicon substrate;

[0032] 200, polysilicon layer;

[0033] 300: silicon dioxide layer;

[0034] 400: piezoelectric layer;

[0035] 500: interdigitated electrodes;

[0036] 600: passivation layer;

[0037] 1-S to 6-S: The first to sixth areas. DETAILED DESCRIPTION

[0038] The technical solution of the present disclosure is further specifically described below through examples and in conjunction with the accompanying drawings. In the specification, the same or similar figure numbers indicate the same or similar parts. The following description of the embodiments of the present disclosure with reference to the accompanying drawings is intended to explain the overall inventive concept of the present disclosure and should not be understood as a limitation on the present disclosure. Some embodiments of the invention, not all embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field are within the scope of protection of the present disclosure.

[0039] like Figure 1 As shown, the distance between the ends of the adjacent first electrode fingers 12 and the second electrode fingers 22 in the direction perpendicular to the propagation direction of the surface acoustic wave (eg Figure 1 The pore size is defined as the pore size or the pore size of the finger. Figure 1 In the surface acoustic wave transducer shown, the aperture size and lateral position (ie, the position in the direction perpendicular to the propagation direction of the surface acoustic wave or along the extension direction of the electrode fingers) are constant, which may cause the problem of lateral energy leakage of the acoustic wave.

[0040] In the present disclosure, the interdigital electrode includes at least one envelope unit, the first envelope and the second envelope defined by the envelope unit are both step traces, and at least two trace points in the first envelope and the corresponding trace points in the second envelope are symmetrical about the same point. The above structure can effectively suppress the performance degradation caused by the lateral mode while maintaining the step of the trace.

[0041] The technical solution of the present disclosure is exemplarily described below with reference to the accompanying drawings.

[0042] Figure 2 FIG. 1 is a schematic top view of a surface acoustic wave transducer according to an exemplary embodiment of the present disclosure. Figure 4 for Figure 2 Schematic diagram of the cross section of the surface acoustic wave transducer. Figure 4 As shown in FIG. 1 , the surface acoustic wave transducer includes a piezoelectric layer 400 and interdigital electrodes 500. The interdigital electrodes 500 are arranged on the surface of the piezoelectric layer 400. Figure 2 As shown, the interdigitated electrode 500 includes a first bus bar 11, a plurality of first electrode fingers 12 connected to the first bus bar 11, a second bus bar 21, and a plurality of second electrode fingers 22 connected to the second bus bar 21. The plurality of first electrode fingers 12 and the plurality of second electrode fingers 22 are arranged in an interlaced manner in the propagation direction of the surface acoustic wave and have an overlapping area. The interdigitated electrode may also include a first virtual finger 13 and a second virtual finger 23. The plurality of first virtual fingers 13 and the plurality of first electrode fingers 12 are alternately connected to the first bus bar 11. The plurality of second virtual fingers 23 and the plurality of second electrode fingers 22 are alternately connected to the second bus bar 21. Each first electrode finger 12 and a corresponding second virtual finger 23 are arranged relative to each other and there is a gap. Each second electrode finger 22 and a corresponding first virtual finger 13 are arranged relative to each other and there is a gap. As known to those skilled in the art, reflectors 31 are also provided on both sides of the interdigitated electrode.

[0043] As known to those skilled in the art, Figure 2 In the figure, the horizontal direction is the propagation direction of the surface acoustic wave.

[0044] Figure 3 Shows Figure 2 The trace and symmetry center of the SAW transducer. Figure 2 and Figure 3 As shown, the interdigitated electrode 500 includes an envelope unit. The envelope unit includes a first envelope 14 defined by the ends of a plurality of first electrode fingers 12, and a second envelope 24 defined by the ends of a plurality of second electrode fingers 22. The end of each first electrode finger 12 constitutes a trace point of the first envelope 14, and the end of each second electrode finger 22 constitutes a trace point of the second envelope 24. Figure 3 , two trace points on the first envelope 14, namely, trace point 51 and trace point 52, and two trace points on the second envelope 24, namely, trace point 53 and trace point 54. It is easy to understand that the first envelope 14 and the second envelope 24 also include other trace points.

[0045] like Figure 3 As shown, the first envelope 14 and the second envelope 24 each include a plurality of horizontal segments, and there is a gradient between adjacent horizontal segments, so the first envelope 14 and the second envelope 24 are both step traces. Figure 3 As shown, when the outer frame of the envelope unit is a rectangle, there is a gradient between adjacent horizontal segments; however, as mentioned later, the outer frame of the envelope unit can also form a parallelogram structure, in which case there is a gradient between adjacent segments parallel to the busbar.

[0046] like Figure 3As shown, at least two trace points in the first envelope 14 and the corresponding trace points in the second envelope 24 are symmetrical about the same point center. It is easy to understand that the outer frame of the envelope unit in the present disclosure is a rectangle, and the center 50 of the rectangle is the symmetry center of the trace points in the first envelope 14 and the trace points in the second envelope 24. Exemplarily, the trace points 51 on the first envelope 14 and the trace points 54 on the second envelope 24 are symmetrical about the symmetry center 50, and the trace points 52 on the first envelope 14 and the trace points 53 on the second envelope 24 are symmetrical about the symmetry center 50. It should also be pointed out that, although not shown, in the case where the outer frame of the envelope unit of the present disclosure is other parallelograms, the intersection of the two diagonals of the parallelogram is the symmetry center. In other words, in the present disclosure, the outer frame of the envelope unit can be not only a rectangle, but also a parallelogram other than a rectangle.

[0047] like Figure 3 As shown, all trace points in the first envelope 14 have corresponding central symmetric relationships. Fig.10 As shown in the upper middle part, a portion of the trace points of the first envelope 14 (exemplarily, the portions in regions 1-S and 6-S) may have a corresponding central symmetric relationship, while another portion (exemplarily, the portions in regions 2-S, 3-S, 4-S, and 5-S) may not have a corresponding central symmetric relationship. In an optional embodiment, as Figure 3 As shown, on each side of the symmetry center 50, the envelope unit includes a plurality of regions adjacent to each other along the propagation direction of the surface acoustic wave. Exemplarily, the plurality of regions include the first region to the third region, i.e., 1-S to 3-S, or 4-S to 6-S in the figure. As can be seen from the symmetry, region 1-S and region 6-S have the same structural parameters (including aperture size and aperture lateral position, etc.), region 2-S and region 5-S have the same structural parameters, and region 3-S and region 4-S have the same structural parameters.

[0048] In the present disclosure, each region defines a plurality of equal finger apertures, e.g. Figure 3 Two finger apertures are defined in each region, and the two finger apertures are equal. Therefore, the end of the real finger in each region defines a horizontal segment of the above-mentioned step trace. It is easy to understand that the number of fingers in each region (here refers to the total number of real fingers and virtual fingers on a single bus bar) is 4 or more.

[0049] In an optional embodiment, if Figure 3As shown, the number of fingers in each area is equal. The above-mentioned number of fingers is equal, and can be approximately equal. For example, when the number of fingers is large (e.g., 50), the number of fingers in each area is allowed to have a small difference (e.g., 3 or 5). In an optional embodiment, the number of fingers in each area is greater than or equal to 10 and less than or equal to 60. In other embodiments, the number of fingers in each area may also be different.

[0050] like Figure 3 As shown, in the propagation direction of the surface acoustic wave, the finger apertures corresponding to the multiple regions on each side of the symmetry center 50 change monotonically from the symmetry center 50 to the outside. Figure 2 In the embodiment, the monotonous change is a sequential decrease. For example, from the symmetric center 50 to the left, the finger apertures corresponding to the regions 3-S, 2-S, and 1-S decrease in sequence, and from the symmetric center 50 to the right, the finger apertures corresponding to the regions 4-S, 5-S, and 6-S decrease in sequence. In other embodiments, although not shown, the monotonous change may be a sequential increase.

[0051] In an optional embodiment, if Figure 3 As shown, the number of regions is an odd number (exemplarily, 3), and the finger aperture of the middle region is the average of the finger apertures of each region. In an optional embodiment, although not shown, the number of regions is an even number, and the finger apertures of the two middle regions are equal and are the average of the finger apertures of each region.

[0052] In an optional embodiment, if Figure 2 As shown, the widths of the first bus bar 11 and the second bus bar 21 are uniform, and the change of the aperture is achieved by changing the lengths of the real finger and the imaginary finger.

[0053] In an optional embodiment, if Figure 2 and Figure 3 As shown, the finger apertures corresponding to each region are located at the center of the envelope unit in the direction perpendicular to the propagation direction of the surface acoustic wave, that is, the finger apertures of each region are centered horizontally, and the outer frame of the envelope unit is a rectangle. As can be understood, when the outer frame of the envelope unit is a parallelogram, the line passing through the symmetry center and parallel to the bus bar is the median line of the finger apertures of each region.

[0054] In an optional embodiment, if Figure 2 and Figure 3 As shown, the change gradients of the finger apertures between adjacent regions are all equal. In other embodiments, although not shown, the change gradients of the finger apertures between adjacent regions may also be different.

[0055] In the present disclosure, the number of regions on each side of the symmetry center 50 can be determined according to specific circumstances, and can be 4 or 5, etc., in addition to 3. It is easy to understand that the number of regions on each side of the symmetry axis is at least 2.

[0056] In each embodiment of the present disclosure, dummy fingers (i.e., dummy electrodes) are provided, so that: the first bus bar 11 is provided with a first dummy finger 13 spaced opposite to the second electrode finger 22 to form a first gap, and the second bus bar 21 is provided with a second dummy finger 23 spaced opposite to the first electrode finger 12 to form a second gap. However, the present disclosure is not limited thereto, and dummy fingers may not be provided.

[0057] In an optional embodiment, the lengths of the first virtual fingers 13 and / or the second virtual fingers 23 in each region are the same. In the propagation direction of the surface acoustic wave, the lengths of the first virtual fingers 13 and / or the second virtual fingers 23 in each region change monotonically from the symmetry center to the outside. Figure 2 and Figure 3 In the above monotonous change, the length of the first electrode finger 12 and / or the second electrode finger 22 in each region increases successively, and can also decrease successively. It is easy to understand that the length of the first electrode finger 12 and / or the second electrode finger 22 in each region changes in the opposite direction to the virtual finger.

[0058] In an optional embodiment, the first gap and / or the second gap in each region are equal, and the first gap and / or the second gap corresponding to each region are equal.

[0059] Figure 5 for Figure 2 Schematic diagram of the interdigitated electrode portion of a surface acoustic wave transducer showing the various dimensions.

[0060] like Figure 5 As shown, W1 is the average of the finger apertures corresponding to multiple regions. When the number of regions on each side of the symmetry axis is 3 and the gradient of the finger apertures between adjacent regions is equal, W1 is the finger aperture of 2-S and 4-S, and W2 is the gradient of the finger apertures between adjacent regions. In an optional embodiment, W1 is 10 to 35 times the wavelength of the surface acoustic wave transducer, that is, W1 = 10 to 35λ. In an optional embodiment, W2 is 0.025 to 0.15 times of W1, W2 = 0.025 to 0.15W1.

[0061] like Figure 5 As shown, Gap is the size of the first gap and / or the second gap, and is also the distance between the real finger and the corresponding virtual finger. In an optional embodiment, Gap is 0.02 to 0.15 times the wavelength of the surface acoustic wave transducer, that is, Gap = 0.02 to 0.15λ.

[0062] like Figure 5As shown, L1 is the length of the first virtual finger and / or the second virtual finger in the first region and the sixth region, L2 is the length of the first virtual finger and / or the second virtual finger in the second region and the fifth region, and L3 is the length of the first virtual finger and / or the second virtual finger in the third region and the fourth region. In an optional embodiment, L1 is 2.4 to 6.4 times the wavelength of the surface acoustic wave transducer, that is, L1 = 2.4 to 6.4λ, L2 is 0.9 to 4.9 times the wavelength of the surface acoustic wave transducer, that is, L2 = 0.9 to 4.9λ, and L3 is 0.2 to 3.4 times the wavelength of the surface acoustic wave transducer, that is, L3: 0.2 to 3.4λ.

[0063] In an optional embodiment, the minimum aperture of the finger-strip apertures corresponding to each region is 4.75 to 34.75 times the wavelength of the surface acoustic wave transducer, and the maximum aperture of the finger-strip apertures corresponding to each two regions is 10.25 to 40.25 times the wavelength of the surface acoustic wave transducer.

[0064] Figure 6 The comparison chart of the test results shows the Figure 1 and Figure 2 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency. Figure 6 In the figure, curve 1 corresponds to Figure 1 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency. Curve 2 corresponds to Figure 2 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency. Figure 6 It can be seen that in each frequency band, Figure 2 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency is compared with Figure 1 The curve of the real part of the admittance of the surface acoustic wave transducer changing with frequency is smoother, indicating that the surface acoustic wave transducer disclosed in the present invention has a better suppression effect on the transverse mode.

[0065] Figure 7 is a comparison chart of the test results, which shows Figure 1 and Figure 2 The quality factor of the surface acoustic wave transducer varies with frequency. Figure 7 In the figure, curve 3 corresponds to Figure 1 The quality factor of the surface acoustic wave transducer varies with frequency. Curve 4 corresponds to Figure 2 The quality factor of the surface acoustic wave transducer varies with frequency. Figure 7 It can be seen that Figure 2 The quality factor curve of the surface acoustic wave transducer is generally higher than that of Figure 1 The curve of the quality factor of the surface acoustic wave transducer changing with frequency is smoother, indicating that the surface acoustic wave transducer in the present disclosure can obtain a higher quality factor.

[0066] Fig.10 A structural comparison diagram of a local central symmetric scheme and a non-central symmetric scheme is shown. Fig.10 The upper middle figure is a local central symmetric scheme. For example, a part of the trace points of the first envelope 14 (exemplarily, the parts in area 1-S and area 6-S) have a corresponding central symmetric relationship, while another part (exemplarily, the parts in areas 2-S, 3-S, 4-S and 5-S) does not have a corresponding central symmetric relationship. Fig.10 The lower figure in the figure is a scheme without central symmetry, that is, all trace points of the first envelope 14 do not have a corresponding central symmetry relationship.

[0067] Fig.11 A comparison chart of the test results of the local central symmetry scheme and the non-central symmetry scheme is shown. Fig.11 In the figure, curve 5 is the variation curve of the real part of admittance with frequency for the scheme without central symmetry, and curve 6 is the variation curve of the real part of admittance with frequency for the scheme with local central symmetry. Fig.11 As shown, curve 6 is smoother than curve 5, which shows that the local central symmetric scheme can achieve better lateral mode suppression effect than the non-central symmetric scheme.

[0068] Figure 8 and Fig. 9 for Figure 2 Variations of the surface acoustic wave transducer. Figure 2 In the embodiment, the interdigitated electrode 500 includes an envelope unit, and in Figure 8 and Fig. 9 In the embodiment, the interdigitated electrodes include Figure 2 The envelope units in form a periodic structure. Figure 2 The interdigitated electrodes in can also be called a single-period structure.

[0069] like Figure 8 As shown in the figure, the interdigital electrode includes two envelope units, which is a double-periodic structure. The double-periodic structure is evolved from the single-periodic structure, so the structural design parameters are the same as the single-periodic design. When the design frequency is low or the number of fingers is relatively small, the double period can be used as a basic unit for filter design. This structure can effectively suppress the lateral mode and improve the filter performance.

[0070] like Fig. 9 As shown in the figure, the interdigital electrode includes three envelope units, which is a three-periodic structure. The three-periodic structure is evolved from the single-periodic structure, so the structural design parameters are the same as the single-periodic design. When designing high frequencies or when the number of fingers is relatively large, the three-period can be used as a basic unit for filter design. This structure can effectively suppress the lateral mode and improve the filter performance.

[0071] exist Figure 8and Fig. 9 In the illustrated embodiment, the interdigitated electrodes include a periodic structure extending with an envelope unit as a period in the propagation direction of the surface acoustic wave. In the propagation direction of the surface acoustic wave, the length of the periodic structure is an integer multiple of the length of the single-period structure. In addition, although not shown, it can also be a non-integer multiple, such as 1.5 times, that is, in the propagation direction of the surface acoustic wave, the length of the periodic structure is a non-integer multiple of the length of the envelope unit. The non-integer multiple here can be reflected in that the single envelope unit at the rear in the propagation direction of the surface acoustic wave includes a part but not all of the single envelope unit at the front in the propagation direction of the surface acoustic wave, or can be reflected in that the single envelope unit at the front in the propagation direction of the surface acoustic wave includes a part but not all of the single envelope unit at the rear in the propagation direction of the surface acoustic wave.

[0072] Although not shown, an envelope unit may be arranged adjacent to another envelope unit or exist adjacent to another envelope unit in the interdigital electrodes of the surface acoustic wave transducer. For example, the length of the single envelope unit at the rear in the propagation direction of the surface acoustic wave is different from the length of the single envelope unit at the front in the propagation direction of the surface acoustic wave. The envelope unit here may be a periodic envelope unit or a non-periodic envelope unit.

[0073] In an alternative implementation, if Figure 4 As shown, the surface acoustic wave transducer also includes a polysilicon layer 200, a silicon dioxide layer 300 and a passivation layer 600. The polysilicon layer 200 is disposed on the silicon substrate 100, the silicon dioxide layer 300 is disposed on the polysilicon layer 200, and the piezoelectric layer 400 is disposed on the silicon dioxide layer 300. The passivation layer 600 covers the interdigital electrodes 500 to play a protective role. The polysilicon layer 200 acts as an energy trap layer, which is beneficial to improving the Q value of the surface acoustic wave transducer.

[0074] In an optional embodiment, the silicon substrate 100 may be made of high-resistance silicon. Optionally, the resistivity of the silicon substrate 100 is greater than 2000 Ω-cm. Further, the resistivity of the silicon substrate 100 is greater than 10000 Ω-cm.

[0075] It should be pointed out that in the present disclosure, for numerical ranges, unless explicitly excluded, the endpoint values ​​are included. In addition, it may also be the midpoint value, one-third value, or two-thirds value of the numerical range.

[0076] The present disclosure also provides a device, comprising the aforementioned surface acoustic wave transducer. The device may be a filter or other device or apparatus using the aforementioned surface acoustic wave transducer.

[0077] Based on the above, the present disclosure proposes the following technical solutions:

[0078] 1. A surface acoustic wave transducer, comprising:

[0079] Piezoelectric layer;

[0080] An interdigitated electrode, disposed on a surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar;

[0081] The interdigitated electrode includes at least one envelope unit, which has a first envelope defined by the ends of the plurality of first electrode fingers and a second envelope defined by the ends of the plurality of second electrode fingers, the first envelope and the second envelope are both step traces, and at least two trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point center.

[0082] 2. The surface acoustic wave transducer according to item 1, wherein:

[0083] All trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point.

[0084] 3. The surface acoustic wave transducer according to item 1, wherein:

[0085] In the propagation direction of the surface acoustic wave, on each side of the symmetry center of the trace point in the first envelope and the trace point in the second envelope, the envelope unit includes at least two adjacent areas along the propagation direction of the surface acoustic wave, and the finger apertures in each of the at least two areas are equal to form a horizontal segment of the step trace.

[0086] 4. The surface acoustic wave transducer according to 3, wherein:

[0087] The number of fingers in the at least two regions is equal.

[0088] 5. The surface acoustic wave transducer according to 3, wherein:

[0089] In the propagation direction of the surface acoustic wave, the finger apertures corresponding to the at least two regions change monotonically from the symmetry center toward the outside.

[0090] 6. The surface acoustic wave transducer according to 5, wherein:

[0091] In the propagation direction of the surface acoustic wave, the finger apertures corresponding to the at least two regions decrease sequentially from the symmetry center toward the outside.

[0092] 7. The surface acoustic wave transducer according to 3, wherein:

[0093] The first bus bar is provided with first dummy fingers spaced opposite to the second electrode fingers to form a first gap, and the second bus bar is provided with second dummy fingers spaced opposite to the first electrode fingers to form a second gap.

[0094] 8. The surface acoustic wave transducer according to item 7, wherein:

[0095] The lengths of the first virtual finger and / or the second virtual finger in each of the at least two regions are the same;

[0096] In the propagation direction of the surface acoustic wave, the lengths of the first virtual fingers and / or the second virtual fingers of the at least two regions vary monotonically from the symmetry center toward the outside.

[0097] 9. The surface acoustic wave transducer according to 8, wherein:

[0098] In the propagation direction of the surface acoustic wave, the lengths of the first virtual fingers and / or the second virtual fingers of the at least two regions increase sequentially from the symmetry center toward the outside.

[0099] 10. The surface acoustic wave transducer according to item 7, wherein:

[0100] The first gap and / or the second gap in each of the at least two regions are equal.

[0101] 11. The surface acoustic wave transducer according to 10, wherein:

[0102] The first gaps and / or second gaps corresponding to the at least two regions are equal.

[0103] 12. The surface acoustic wave transducer according to item 7, wherein:

[0104] The first gap and / or the second gap corresponding to each of the at least two regions is / are 0.02 times to 0.15 times the wavelength of the surface acoustic wave transducer.

[0105] 13. The surface acoustic wave transducer according to 3, wherein:

[0106] The at least two regions include first to third regions that are adjacent to each other in sequence, and the third region is adjacent to the symmetry axis.

[0107] 14. The surface acoustic wave transducer according to 13, wherein:

[0108] The length of the first virtual finger and / or the second virtual finger in the first region is 2.4 times to 6.4 times the wavelength of the surface acoustic wave transducer, the length of the first virtual finger and / or the second virtual finger in the second region is 0.9 times to 4.9 times the wavelength of the surface acoustic wave transducer, and the length of the first virtual finger and / or the second virtual finger in the third region is 0.2 times to 3.4 times the wavelength of the surface acoustic wave transducer.

[0109] 15. The surface acoustic wave transducer according to 3, wherein:

[0110] The at least two regions include at least three regions;

[0111] The variation gradients of the finger apertures between adjacent regions in the at least three regions are all equal.

[0112] 16. The surface acoustic wave transducer according to 3, wherein:

[0113] The at least two regions include at least three regions;

[0114] The finger aperture diameter of the middle area among the at least three areas is the average value of the finger aperture diameters of the at least three areas.

[0115] 17. The surface acoustic wave transducer according to 3, wherein:

[0116] The average value of the finger apertures corresponding to the at least two regions is 10 to 35 times the wavelength of the surface acoustic wave transducer.

[0117] 18. The surface acoustic wave transducer according to 3, wherein:

[0118] The variation gradient of the finger apertures between adjacent regions in the at least two regions is 0.025 times to 0.15 times the average value of the finger apertures corresponding to the at least two regions.

[0119] 19. The surface acoustic wave transducer according to 3, wherein:

[0120] The number of fingers in each of the at least two areas is greater than or equal to 10 and less than or equal to 60.

[0121] 20. The surface acoustic wave transducer according to item 1, wherein:

[0122] The interdigital electrode comprises a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the interdigital electrode comprises at least two envelope units arranged in sequence and adjacent to each other in the propagation direction of the surface acoustic wave.

[0123] 21. The surface acoustic wave transducer according to item 1, wherein:

[0124] The interdigital electrode comprises a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the interdigital electrode comprises at least three envelope units arranged in sequence and adjacent to each other in the propagation direction of the surface acoustic wave.

[0125] 22. The surface acoustic wave transducer according to item 1, wherein:

[0126] The interdigitated electrodes include a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the length of the periodic structure in the propagation direction of the surface acoustic wave is a non-integer multiple of the length of the envelope unit; or

[0127] The interdigital electrode includes two different envelope units arranged adjacent to each other.

[0128] 23. The surface acoustic wave transducer according to item 1, wherein:

[0129] The first bus bar and the second bus bar have uniform widths.

[0130] 24. A surface acoustic wave transducer, comprising:

[0131] Piezoelectric layer;

[0132] An interdigitated electrode, disposed on a surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar;

[0133] The interdigitated electrode comprises at least one envelope unit, the envelope unit having a first envelope defined by ends of the plurality of first electrode fingers and a second envelope defined by ends of the plurality of second electrode fingers, the first envelope and the second envelope are both step traces, and at least two trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point center;

[0134] The smallest aperture among the finger apertures of the envelope unit is 4.75 to 34.75 times the wavelength of the surface acoustic wave transducer, and / or the largest aperture among the finger apertures of the envelope unit is 10.25 to 40.25 times the wavelength of the surface acoustic wave transducer.

[0135] 25. A device comprising the surface acoustic wave transducer according to any one of 1-24.

[0136] Although embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A surface acoustic wave transducer, comprising: Piezoelectric layer; An interdigitated electrode, disposed on a surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar; The interdigitated electrode includes at least one envelope unit, which has a first envelope defined by the ends of the plurality of first electrode fingers and a second envelope defined by the ends of the plurality of second electrode fingers, the first envelope and the second envelope are both step traces, and at least two trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point center.

2. The surface acoustic wave transducer according to claim 1, wherein: All trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point.

3. The surface acoustic wave transducer according to claim 1, wherein: In the propagation direction of the surface acoustic wave, on each side of the symmetry center of the trace point in the first envelope and the trace point in the second envelope, the envelope unit includes at least two adjacent areas along the propagation direction of the surface acoustic wave, and the finger apertures in each of the at least two areas are equal to form a horizontal segment of the step trace.

4. The surface acoustic wave transducer according to claim 3, wherein: The number of fingers in the at least two regions is equal.

5. The surface acoustic wave transducer according to claim 3, wherein: In the propagation direction of the surface acoustic wave, the finger apertures corresponding to the at least two regions change monotonically from the symmetry center toward the outside.

6. The surface acoustic wave transducer according to claim 5, wherein: In the propagation direction of the surface acoustic wave, the finger apertures corresponding to the at least two regions decrease sequentially from the symmetry center toward the outside.

7. The surface acoustic wave transducer according to claim 3, wherein: The first bus bar is provided with first dummy fingers spaced opposite to the second electrode fingers to form a first gap, and the second bus bar is provided with second dummy fingers spaced opposite to the first electrode fingers to form a second gap.

8. The surface acoustic wave transducer according to claim 7, wherein: The lengths of the first virtual finger and / or the second virtual finger in each of the at least two regions are the same; In the propagation direction of the surface acoustic wave, the lengths of the first virtual fingers and / or the second virtual fingers of the at least two regions vary monotonically from the symmetry center toward the outside.

9. The surface acoustic wave transducer according to claim 8, wherein: In the propagation direction of the surface acoustic wave, the lengths of the first virtual fingers and / or the second virtual fingers of the at least two regions increase sequentially from the symmetry center toward the outside.

10. The surface acoustic wave transducer according to claim 7, wherein: The first gap and / or the second gap in each of the at least two regions are equal.

11. The surface acoustic wave transducer according to claim 10, wherein: The first gaps and / or second gaps corresponding to the at least two regions are equal.

12. The surface acoustic wave transducer according to claim 7, wherein: The first gap and / or the second gap corresponding to each of the at least two regions is / are 0.02 times to 0.15 times the wavelength of the surface acoustic wave transducer.

13. The surface acoustic wave transducer according to claim 3, wherein: The at least two regions include first to third regions that are adjacent to each other in sequence, and the third region is adjacent to the symmetry axis.

14. The surface acoustic wave transducer according to claim 13, wherein: The length of the first virtual finger and / or the second virtual finger in the first region is 2.4 times to 6.4 times the wavelength of the surface acoustic wave transducer, the length of the first virtual finger and / or the second virtual finger in the second region is 0.9 times to 4.9 times the wavelength of the surface acoustic wave transducer, and the length of the first virtual finger and / or the second virtual finger in the third region is 0.2 times to 3.4 times the wavelength of the surface acoustic wave transducer.

15. The surface acoustic wave transducer according to claim 3, wherein: The at least two regions include at least three regions; The variation gradients of the finger apertures between adjacent regions in the at least three regions are all equal.

16. The surface acoustic wave transducer according to claim 3, wherein: The at least two regions include at least three regions; The finger aperture diameter of the middle area among the at least three areas is the average value of the finger aperture diameters of the at least three areas.

17. The surface acoustic wave transducer according to claim 3, wherein: The average value of the finger apertures corresponding to the at least two regions is 10 to 35 times the wavelength of the surface acoustic wave transducer.

18. The surface acoustic wave transducer according to claim 3, wherein: The variation gradient of the finger apertures between adjacent regions in the at least two regions is 0.025 times to 0.15 times the average value of the finger apertures corresponding to the at least two regions.

19. The surface acoustic wave transducer according to claim 3, wherein: The number of fingers in each of the at least two areas is greater than or equal to 10 and less than or equal to 60.

20. The surface acoustic wave transducer according to claim 1, wherein: The interdigital electrode comprises a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the interdigital electrode comprises at least two envelope units arranged in sequence and adjacent to each other in the propagation direction of the surface acoustic wave.

21. The surface acoustic wave transducer according to claim 1, wherein: The interdigital electrode comprises a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the interdigital electrode comprises at least three envelope units arranged in sequence and adjacent to each other in the propagation direction of the surface acoustic wave.

22. The surface acoustic wave transducer according to claim 1, wherein: The interdigitated electrodes include a periodic structure extending with the envelope unit as a period in the propagation direction of the surface acoustic wave, and the length of the periodic structure in the propagation direction of the surface acoustic wave is a non-integer multiple of the length of the envelope unit; or The interdigital electrode includes two different envelope units arranged adjacent to each other.

23. The surface acoustic wave transducer according to claim 1, wherein: The first bus bar and the second bus bar have uniform widths.

24. A surface acoustic wave transducer, comprising: Piezoelectric layer; An interdigitated electrode, disposed on a surface of the piezoelectric layer, comprising: a first bus bar and a plurality of first electrode fingers connected to the first bus bar, a second bus bar and a plurality of second electrode fingers connected to the second bus bar; The interdigitated electrode comprises at least one envelope unit, the envelope unit having a first envelope defined by ends of the plurality of first electrode fingers and a second envelope defined by ends of the plurality of second electrode fingers, the first envelope and the second envelope are both step traces, and at least two trace points in the first envelope and corresponding trace points in the second envelope are symmetrical about the same point center; The smallest aperture among the finger apertures of the envelope unit is 4.75 to 34.75 times the wavelength of the surface acoustic wave transducer, and / or the largest aperture among the finger apertures of the envelope unit is 10.25 to 40.25 times the wavelength of the surface acoustic wave transducer.

25. A device comprising the surface acoustic wave transducer according to any one of claims 1 to 24.

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