Surface acoustic wave resonator and filter

Abstract

The invention discloses a surface acoustic wave resonator and a filter, and the resonator comprises an interdigital structure which comprises a first interdigital region and a second interdigital region; the first interdigital area comprises a plurality of first finger strips, and the second interdigital area comprises a plurality of second finger strips; the reflecting gratings are arranged on the two sides of the interdigital structure in the first direction, and the reflecting gratings, the first finger strips and the second finger strips are located on the same plane; the reflecting grating and the plurality of first finger strips are vertically crossed with each other, and the reflecting grating and the plurality of second finger strips are vertically crossed with each other; in the first direction, each first finger strip and each second finger strip are oppositely arranged, and a gap is formed between each first finger strip and the corresponding second finger strip; in the second direction, the multiple first finger strips are arranged in parallel, and the multiple second finger strips are arranged in parallel; the first direction is perpendicular to the second direction. According to the invention, the leakage of transverse energy in the first direction can be reduced, and the high-order stray mode of the surface acoustic wave resonator in the first direction and the second direction can be suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, in particular to a surface acoustic wave resonator and a filter. Background Art

[0002] Surface acoustic wave (SAW) devices have the characteristics of high quality factor and miniaturization, and are widely used in wireless communication, sensing and filtering. However, in practical applications, the performance of SAW devices is seriously affected by high-order modal interference including transverse mode and longitudinal mode, which not only reduces the frequency purity of the resonator, but also causes energy leakage and signal noise increase, thus affecting the overall performance of the device.

[0003] The generation of transverse modes is mainly related to the lateral leakage of acoustic wave energy in the interdigital transducer. The transversely propagated energy deviates from the main propagation direction and forms parasitic signals, interfering with the normal operation of the device. The high-order modes of the longitudinal mode are caused by the structural characteristics of the interdigital electrodes, which will generate additional resonance peaks in the main propagation direction, causing clutter in the signal and reducing the frequency selectivity and stability of the device. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to improve the ability to suppress high-order modes.

[0005] In order to solve at least one of the above-mentioned technical problems, the present invention discloses a surface acoustic wave resonator and a filter.

[0006] According to one aspect of the present disclosure, there is provided a surface acoustic wave resonator, comprising: An interdigital structure, comprising a first interdigital region and a second interdigital region; the first interdigital region comprises a plurality of first fingers, and the second interdigital region comprises a plurality of second fingers; A reflective grating is disposed on both sides of the interdigitated structure in a first direction, and the reflective grating, the plurality of first fingers, and the plurality of second fingers are located in the same plane; the reflective grating and the plurality of first fingers intersect each other, and the reflective grating and the plurality of second fingers intersect each other; In the first direction, each first finger is arranged opposite to each second finger, and an opposing distance is formed between the first finger and the second finger; In the second direction, the plurality of first fingers are arranged in parallel, and the plurality of second fingers are arranged in parallel.

[0007] In some possible embodiments, in the first interdigitated region, in the second direction, each of the first fingers has a first finger width, and among the plurality of first fingers, any two adjacent first fingers have a first finger spacing; The sum of the first finger width and the first finger spacing is a first stripe period; the first stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the first finger width to the first stripe period is a first duty cycle corresponding to the first finger; the first duty cycle ranges from 0.4 to 0.65.

[0008] In some possible embodiments, each of the first fingers has a first finger length extending along the first direction; The length of the first finger is determined according to the order of the first fingers in the second direction and the number of the plurality of first fingers.

[0009] In some possible embodiments, in the second interdigitated region, in the second direction, each of the second fingers has a second finger width, and any two adjacent second fingers among the plurality of second fingers have a second finger spacing; The sum of the second finger width and the second finger spacing is the second stripe period; the second stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the second finger width to the second stripe period is a second duty cycle corresponding to the second finger; and the second duty cycle is in a range of 0.4 to 0.65.

[0010] In some possible embodiments, each of the second fingers has a second finger length extending along the first direction; The length of the second finger is determined according to the order of the second fingers in the second direction and the number of the plurality of second fingers.

[0011] In some possible embodiments, the interdigitated structure includes a plurality of first fingers and a plurality of opposing spacings formed between the plurality of second fingers; The plurality of opposing intervals are parallel to each other in the second direction and are staggeredly distributed around a central axis of the interdigitated structure.

[0012] In some possible embodiments, the spacing of the opposing spacing ranges from 0.2 μm to 10.5 μm.

[0013] In some possible embodiments, the reflective grating includes a plurality of reflective grating strips arranged in parallel in the first direction; In the first direction, each reflective grating has a grating width; the grating width is determined according to the first stripe period and / or the second stripe period.

[0014] In some possible embodiments, any two adjacent reflective strips form a stripe spacing in the first direction; the stripe spacing is determined according to the first stripe period and / or the second stripe period.

[0015] In some possible embodiments, a size of each of the reflective gratings in the second direction is greater than or equal to a size of the interdigital structure in the second direction.

[0016] In some possible embodiments, the plurality of reflective gratings, the first finger strips and the second finger strips form a plurality of reflective holes; The plurality of reflective holes are arranged at first intervals in the first direction, and are arranged at second intervals in the second direction.

[0017] In some possible embodiments, the shapes and sizes of the multiple reflective holes are the same, and the shape of the reflective holes is rectangular or diamond; When the shape of the multiple reflective holes is rhombus, the angle between any of the reflective grating strips and the first finger strips and / or the second finger strips in the first direction ranges from 60° to 85°.

[0018] According to a second aspect of the present disclosure, a filter is provided, comprising any surface acoustic wave resonator as described above.

[0019] The implementation of the present invention has the following beneficial effects: In the present invention, the surface acoustic wave resonator includes a finger region and a reflection grating. In the finger region, the parallel and spaced fingers can uniformly excite the surface acoustic wave, avoiding uneven excitation of the acoustic wave caused by the irregular distribution of the fingers, thereby generating a clear and stable main propagation mode and improving the consistency of the frequency response. The reflection grating is arranged on both sides of the finger region, and is located in the same plane as the finger region and intersects with each other, so that the reflection grating can efficiently reflect the laterally propagated acoustic wave energy and guide it back to the main propagation direction, thereby improving the utilization efficiency of the acoustic wave energy and reducing the interference of the lateral mode on the resonator performance. In addition, setting the reflection grating and the finger region in the same plane can reduce the complexity of the multi-layer manufacturing process, thereby reducing the alignment error and manufacturing cost; at the same time, it can avoid the problem of interlayer scattering and improve the energy utilization efficiency and signal purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A first structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention; Figure 2 A second structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention; Figure 3 A third structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention; Figure 4 A first structural schematic diagram corresponding to the reflection grating provided in an embodiment of the present invention; Figure 5 A second structural schematic diagram corresponding to the reflective grating provided in an embodiment of the present invention; Figure 6 A third structural schematic diagram corresponding to the reflective grating provided in an embodiment of the present invention; Figure 7 A fourth structural schematic diagram corresponding to the reflective grating provided in an embodiment of the present invention; Figure 8 Admittance diagrams corresponding to comparisons of two resonators provided in a specific embodiment of the present invention; Fig. 9 A dB value curve diagram showing a comparison of two resonators provided in a specific embodiment of the present invention.

[0022] The reference numerals may include: 100 - interdigital structure, 110 - first interdigital region, 111 - first finger strip, 120 - second interdigital region, 121 - second finger strip; 130 - opposite spacing; 200-reflection grid, 210-reflection grid bar, 220-reflection hole; 300-center axis; W1- first finger width, W2- second finger width, W3- grid width; S1-first finger spacing, S2-second finger spacing; S3-grid spacing. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, such as a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0025] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0026] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0027] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0028] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure.

[0029] Figure 1FIG. 1 shows a first structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention; Figure 1 As shown, the first direction is the horizontal x direction, and the second direction is the vertical y direction; a surface acoustic wave resonator may include: The interdigital structure 100 includes a first interdigital region 110 and a second interdigital region 120; the first interdigital region 110 includes a plurality of first fingers 111, and the second interdigital region 120 includes a plurality of second fingers 121; the interdigital structure 100 also includes a plurality of opposing spacings 130 formed between the plurality of first fingers 111 and the plurality of second fingers 121; the plurality of opposing spacings 130 are parallel to each other in the second direction and are staggeredly distributed around the central axis 300 of the interdigital structure 100; The reflective grating 200 is disposed on both sides of the interdigital structure 100 in the first direction. The reflective grating 200 and the plurality of first fingers 111 and the plurality of second fingers 121 are located in the same plane. The reflective grating 200 and the plurality of first fingers 111 intersect with each other, and the reflective grating 200 and the plurality of second fingers 121 intersect with each other. In the first direction, each first finger 111 is arranged opposite to each second finger 121, and an opposing interval 130 is formed between the first finger 111 and the second finger 121; In the second direction, the plurality of first fingers 111 are arranged in parallel, and the plurality of second fingers 121 are arranged in parallel.

[0030] In a specific embodiment, Figure 1 As shown, the surface acoustic wave resonator may include a finger structure 100 and a reflection grating 200 disposed on both sides of the finger structure 100, wherein the finger structure 100 is perpendicular to the reflection grating 200 and is located in the same layer. The finger structure 100 can be considered as an interdigital transducer, including a plurality of fingers, and an opposing spacing 130 formed by the fingers being opposed to each other in a first direction. The plurality of opposing spacings 130 are parallel to each other in a second direction and are staggered around the central axis 300 of the finger structure 100; the plurality of fingers are arranged to form an interdigital structure to realize the excitation of an acoustic wave signal.

[0031] Specifically, the interdigital structure 100 can be made on a piezoelectric material substrate, such as quartz, lithium tantalate or lithium niobate, and the substrate can include a layer of material or multiple layers of material, and the layer or multiple layers of material can support passivation, temperature compensation, power processing, mode suppression, etc. The main materials include lithium niobate LN, lithium tantalate LT, aluminum nitride (AlN), silicon dioxide (SiO2), polycrystalline silicon (ploy-Si), amorphous silicon, silicon nitride (SiN), silicon oxynitride (SiON), scandium-doped aluminum nitride (AlScN), non-conductive materials (such as silicon (Si), doped silicon, sapphire, silicon carbide (SiC), fused silica, glass, diamond, etc.) and combinations or doped compounds of the above materials. The characteristics of piezoelectric materials enable electrical signals to be converted into sound waves. The interdigital structure 100 can be divided into a first interdigital region 110 including a first finger 111 and a second interdigital region 120 including a second finger 121 according to an opposing spacing 130; wherein the opposing spacing 130 is the distance between the first finger 111 and the second finger 121 in the first direction. The interdigital structure 100 is divided into the first interdigital region 110 and the second interdigital region 120 according to the opposing spacing 130, that is, the finger on the left side of the opposing spacing 130 is the first finger 111, and the area including the first finger 111 on the left side of the opposing spacing 130 is the first interdigital region 110; the finger on the right side of the opposing spacing 130 is the second finger 121, and the area including the second finger 121 on the right side of the opposing spacing 130 is the second interdigital region 120. It should be noted that the division of the first interdigital region 110 and the second interdigital region 120 in the present invention is for the convenience of describing the surface acoustic wave resonator structure, but it is not necessary to divide the interdigital structure 100 into the first interdigital region 110 and the second interdigital region 120 in actual applications. In addition, the rectangular frame of any figure in the drawings of the specification is only used to clearly mark the position of the structure, rather than to describe its actual structure, size, etc.

[0032] In the embodiment of the present invention, the interdigital structure 100 excites the acoustic wave and cooperates with the opposing spacing 130 to suppress high-order mode clutter. The reflective gratings 200 on both sides of the interdigital structure 100 reflect the energy of the lateral mode, thereby reducing the lateral leakage of signal energy and further improving the signal quality.

[0033] Figure 2 A second structural diagram of a surface acoustic wave resonator provided in an embodiment of the present invention is used to identify structures, parameters, etc. related to the first interdigital region 110 in the surface acoustic wave resonator; Figure 2 As shown, in the first interdigitated region 110, in the second direction, each of the first fingers 111 has a first finger width W1, and among the plurality of first fingers 111, any two adjacent first fingers 111 have a first finger spacing S1; The sum of the first finger width W1 and the first finger spacing S1 is a first stripe period; the first stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the first finger width W1 to the first stripe period is a first duty cycle corresponding to the first finger 111; the first duty cycle ranges from 0.4 to 0.65.

[0034] Each of the first fingers 111 has a first finger length extending along the first direction; The length of the first finger is determined according to the order of the first fingers 111 in the second direction and the number of the plurality of first fingers 111 .

[0035] In a specific embodiment, the first interdigitated region 110 includes a plurality of first fingers 111 arranged in parallel in the second direction, wherein each first finger 111 has a first finger width W1 in the second direction, and each first finger 111 also has a first finger length extending along the first direction in the first direction.

[0036] For the first finger width W1, in the second direction, a first finger spacing S1 is formed between any two adjacent first fingers 111, and a plurality of first fingers 111 respectively form a plurality of first finger spacings S1. The sum of the first finger spacing S1 and the first finger width W1 is the first stripe period, and the value range of the first stripe period is 0.3μm~3.5μm, and the preferred range can be 0.85μm~2.5μm, for example, the first stripe period can be 1.5μm. The ratio of the first finger width W1 to the first stripe period is the first duty cycle, and the value range of the first duty cycle is 0.4~0.65, and preferably can be 0.5. The first stripe period is a basic parameter of the periodic structure, which can be used to describe the periodicity of the first fingers 111 and the arrangement of the first finger spacing S1, and is the basic unit of repetition of the first fingers 111 and the first finger spacing S1; the first duty cycle is used to describe the proportion of the effective part (i.e., the first finger width W1) to the first stripe period.

[0037] The first finger length L1 is determined by the order of the first fingers 111 in the second direction and the number of the first fingers 111. In addition, the first finger length L1 may also be related to a proportionality coefficient. Specifically, the first finger length L1 may be calculated by the following formula:

[0038] Wherein, i is the order of the first fingers 111 in the first interdigitated structure 100 in the second direction, n is the number of the plurality of first fingers 111 in the first interdigitated structure 100, A is the first proportional coefficient, and B is the second proportional coefficient; wherein, n≥20 and preferably 75, A≤30μm and preferably 5μm, B≥20*first strip period and preferably B=40*first strip period.

[0039] By limiting the value range of the first stripe period and the first duty cycle, the first finger width W1, the first finger length and the first finger spacing S1 are adjusted. The size setting under the above restrictions can improve the suppression capability of the longitudinal and lateral high-order spurious modes. At the same time, it can ensure that the first finger length and the first finger width W1 are appropriate, thereby avoiding the etching difficulty caused by too small length and / or width, or the photolithography distortion caused by too large length and / or width.

[0040] Figure 3 A third structural diagram of a surface acoustic wave resonator provided in an embodiment of the present invention is used to identify structures, parameters, etc. related to the second interdigital region 120 in the surface acoustic wave resonator; Figure 3 In the second interdigitated region 120, in the second direction, each second finger 121 has a second finger width W2, and any two adjacent second fingers 121 in the plurality of second fingers 121 have a second finger spacing S2; The sum of the second finger width W2 and the second finger spacing S2 is the second stripe period; the second stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the second finger width W2 to the second stripe period is a second duty cycle corresponding to the second finger 121; the second duty cycle ranges from 0.4 to 0.65.

[0041] Each of the second fingers 121 has a second finger length extending along the first direction; The second finger length is determined according to the order of the second fingers 121 in the second direction and the number of the plurality of second fingers 121 .

[0042] In a specific embodiment, the multiple second fingers 121 included in the second interdigitated region 120 are arranged in parallel in the second direction, wherein each second finger 121 has a second finger width W2 in the second direction, and each second finger 121 also has a second finger length extending along the first direction.

[0043] For the second finger width W2, in the second direction, a second finger spacing S2 is formed between any two adjacent second fingers 121, and multiple second fingers 121 respectively form multiple second finger spacings S2. The sum of the second finger spacing S2 and the second finger width W2 is the second strip period, and the value range of the second strip period is 0.3μm~3.5μm, and the preferred range can be 0.85μm~2.5μm, for example, the second strip period can be 1.5μm. The ratio of the second finger width W2 to the second strip period is the second duty cycle, and the value range of the second duty cycle is 0.4~0.65, and preferably can be 0.5. The second strip period is a basic parameter of the periodic structure, which can be used to describe the periodicity of the second fingers 121 and the arrangement of the second finger spacing S2, and is the basic unit of repetition of the second fingers 121 and the second finger spacing S2; the second duty cycle is used to describe the proportion of the effective part (i.e., the second finger width W2) to the second strip period.

[0044] The value of the second finger length L2 is determined by the order of the second fingers 121 in the second direction and the number of the second fingers 121. In addition, the second finger length L2 may also be related to the proportionality coefficient. Specifically, the second finger length L2 may be calculated by the following formula:

[0045] Wherein, j is the order of the second fingers 121 in the second finger structure 100 in the second direction, m is the number of the plurality of second fingers 121 in the second finger structure 100, A is the second proportional coefficient, and B is the second proportional coefficient; wherein, m≥20 and preferably 75, A≤30μm and preferably 5μm, B≥20*second strip period and preferably B=40*second strip period.

[0046] In addition, in order to realize that the first finger 111 and the second finger 121 can be mutually opposed, the first finger width W1 and the second finger width W2 need to be set equal, and the first finger spacing S1 and the second finger spacing S2 need to be set equal. By adjusting the length of the first finger 111 and the length of the second finger 121, the opposing spacing 130 between the first finger 111 and the second finger 121 is changed, thereby adjusting the distribution or characteristics of the interdigital structure 100, changing the excitation coefficient of the first finger 111 and / or the second finger 121, reducing the excitation efficiency of the high-order mode, and then suppressing the longitudinal and lateral high-order clutter modes.

[0047] like Figure 1-Figure 3 As shown in any of the above, in the surface acoustic wave resonator, the reflection grating 200 includes a plurality of reflection grating strips 210 arranged in parallel in the first direction; In the first direction, each reflective grating 210 has a grating width W3; the grating width W3 is determined according to the first stripe period and / or the second stripe period.

[0048] Any two adjacent reflective grating strips 210 form a grating strip spacing S3 in the first direction; the grating strip spacing S3 is determined according to the first strip period and / or the second strip period.

[0049] The size of each of the reflective gratings 210 in the second direction is greater than or equal to the size of the interdigital structure 100 in the second direction.

[0050] In a specific embodiment, the reflective grid 200 includes a plurality of reflective grid bars 210 arranged in parallel in a first direction. Figure 4-Figure 7 A plurality of structural schematic diagrams corresponding to the reflective grating 200 provided in the embodiment of the present invention are shown in FIG. Figure 4-Figure 7 As shown in any example, in the first direction, each reflective grating 210 has a grating width W3, and a grating spacing S3 is formed between two adjacent reflective gratings 210. The determination of the grating width W3 and the grating spacing S3 is related to the first strip period and / or the second strip period, wherein the first strip period is generally equal to the second strip period.

[0051] Specifically, the value range of the grid width W3 can be λ / 16~λ / 4, and the value range of the grid spacing S3 can be λ / 16~λ / 4, where λ is the wavelength, and λ=2*first strip period can be set. Preferably, the grid width W3 is set equal to the grid spacing S3, which is λ / 8.

[0052] In addition, in the second direction, the size of each reflective grating 210 is set to be larger than the size of the interdigital structure 100. When the coverage of the reflective grating 200 in the second direction is larger than that of the interdigital structure 100, a complete reflective boundary can be provided for the interdigital region, reducing the transversely propagating sound waves or electromagnetic waves entering the interdigital region, thereby effectively suppressing unnecessary stray waves or reflected waves, and improving the purity of the signal. At the same time, the reflection effect can be better enhanced, the quality factor of the resonator can be improved, and the frequency selectivity can be improved, so that the device has better working performance at the target frequency.

[0053] For the reflector 200, the material selection can also affect the suppression performance of the transverse mode. The metal with a higher density has a better suppression effect on the transverse mode. The metal can be one or more layers of metal, or a bonding layer of one or more metals. The metal can be aluminum, copper, silver, gold, tungsten, chromium, titanium, molybdenum, or a combination of the above metals or doped metals.

[0054] By combining the first strip period and / or the second strip period to limit the grid strip spacing S3 and the grid strip width W3, the resonant frequency of the main propagation mode is optimized, and the interference of high-order modes is reduced, thereby improving the frequency selectivity and signal purity of the surface acoustic wave resonator. At the same time, the acoustic wave energy can be concentrated on the main propagation path, reducing lateral energy leakage, improving energy utilization efficiency and the suppression performance of stray modes.

[0055] like Figure 1-Figure 3 As shown in any of the above, in the surface acoustic wave resonator, the plurality of reflection grating strips 210 and the first finger strips 111 and the second finger strips 121 form a plurality of reflection holes 220; the plurality of reflection holes 220 are arranged at first intervals in the first direction and at second intervals in the second direction.

[0056] The shapes and sizes of the multiple reflective holes 220 are the same, and the shapes of the reflective holes 220 are rectangular or rhombus-shaped. When the shapes of the multiple reflective holes 220 are rhombus-shaped, the angle between any of the reflective gratings 210 and the first finger bar 111 and / or the second finger bar 121 in the first direction ranges from 60° to 85°.

[0057] In a specific embodiment, the plurality of reflective bars 210 located on both sides of the interdigital structure 100 cooperate with the first finger bars 111 and the second finger bars 121 to form a plurality of reflective holes 220. The shape of the reflective holes 220 can be rectangular, diamond, elliptical, or triangular. Figure 1-Figure 3 As shown in any example, when the shape of the reflective hole 220 is a rectangle, the reflective grid 200 and the first finger strips 111 and / or the second finger strips 121 are mutually intersecting and perpendicular in the same plane; Figure 4 As shown, when the shape of the reflective hole 220 is a rhombus, the angle θ between the reflective grating 210 and the first finger 111 and / or the second finger 121 in the first direction may be in the range of 60° to 85°, and preferably 80°; Figure 5 As shown, when the shape of the reflective hole 220 is an isosceles triangle, the grid bar spacing S3 is the height of the isosceles triangle; Figure 6 As shown, when the shape of the reflective hole 220 is a right triangle, the grid bar spacing S3 is one of its right angle sides; Figure 7 As shown, when the shape of the reflective hole 220 is an ellipse, the grid bar spacing S3 is the length of its short side. The shape of the reflective hole 220 can affect the suppression effect on the transverse mode. Specifically, it can be considered that the suppression ability of the rectangular reflective hole is better than that of the rhombus reflective hole, the suppression ability of the rhombus reflective hole is better than that of the elliptical reflective hole, the suppression ability of the elliptical reflective hole is better than that of the isosceles triangle reflective hole, and the suppression ability of the isosceles triangle reflective hole is better than that of the right triangle reflective hole.

[0058] Figure 8The corresponding admittance diagrams of two resonators provided in a specific embodiment of the present invention are shown in FIG. Figure 8 , Figure 8 The abscissa in the figure represents frequency, the ordinate represents admittance, the blue curve represents the admittance curve of the surface acoustic wave resonator in the prior art, and the red curve represents the admittance curve of the surface acoustic wave resonator provided in this embodiment; Fig. 9 A curve of dB value of the real part of admittance corresponding to two resonators provided in a specific embodiment of the present invention is shown in FIG. Fig. 9 , Fig. 9 The horizontal axis in the figure represents the frequency, the vertical axis represents the dB value of the real part of the admittance, the blue curve represents the dB value curve of the real part of the admittance of the surface acoustic wave resonator in the prior art, and the red curve represents the dB value curve of the real part of the admittance of the surface acoustic wave resonator provided in this embodiment, wherein the pink frame can reflect the suppression performance of the longitudinal mode, and the yellow frame can reflect the suppression performance of the transverse mode. Figure 8-Figure 9 It can be seen that, compared with the prior art, the resonator disclosed in the present invention can achieve better longitudinal mode suppression and transverse mode suppression effects, has good modulation performance, and can reduce the impact of interference signals.

[0059] Based on the same inventive concept, an embodiment of the present invention further provides a filter, including the surface acoustic wave resonator in the above embodiment. Therefore, the filter provided by the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be repeated here.

[0060] It can be seen from the embodiments provided by the present invention that in the present invention, the surface acoustic wave resonator includes a forked finger region and a reflective grating. In the forked finger region, the parallel and spaced fingers can uniformly excite the surface acoustic wave, avoiding uneven acoustic wave excitation caused by irregular distribution of the fingers, thereby generating a clear and stable main propagation mode and improving the consistency of the frequency response. The reflective grating is arranged on both sides of the forked finger region, and is located in the same plane as the forked finger region and is perpendicular to each other, so that the reflective grating can efficiently reflect the laterally propagated acoustic wave energy and guide it back to the main propagation direction, thereby improving the utilization efficiency of the acoustic wave energy and reducing the interference of the lateral mode on the resonator performance. In addition, setting the reflective grating and the forked finger region in the same plane can reduce the complexity of the multi-layer manufacturing process, thereby reducing the alignment error and manufacturing cost; at the same time, it can avoid the problem of interlayer scattering and improve the energy utilization efficiency and signal purity.

[0061] It should be noted that various embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used in this article is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A surface acoustic wave resonator, characterized in that: Having a first direction and a second direction perpendicular to each other, the resonator comprises: An interdigital structure, comprising a first interdigital region and a second interdigital region; the first interdigital region comprises a plurality of first fingers, and the second interdigital region comprises a plurality of second fingers; A reflective grating is disposed on both sides of the interdigitated structure in a first direction, and the reflective grating, the plurality of first fingers, and the plurality of second fingers are located in the same plane; the reflective grating and the plurality of first fingers intersect each other, and the reflective grating and the plurality of second fingers intersect each other; In the first direction, each first finger is arranged opposite to each second finger, and an opposing distance is formed between the first finger and the second finger; In the second direction, the plurality of first fingers are arranged in parallel, and the plurality of second fingers are arranged in parallel.

2. A surface acoustic wave resonator according to claim 1, characterized in that: In the first interdigitated region, in the second direction, each of the first fingers has a first finger width, and any two adjacent first fingers among the plurality of first fingers have a first finger spacing; The sum of the first finger width and the first finger spacing is a first stripe period; the first stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the first finger width to the first stripe period is a first duty cycle corresponding to the first finger; the first duty cycle ranges from 0.4 to 0.

65.

3. A surface acoustic wave resonator according to claim 2, characterized in that: Each of the first fingers has a first finger length extending along the first direction; The length of the first finger is determined according to the order of the first fingers in the second direction and the number of the plurality of first fingers.

4. A surface acoustic wave resonator according to claim 1, characterized in that: In the second interdigitated region, in the second direction, each of the second fingers has a second finger width, and any two adjacent second fingers among the plurality of second fingers have a second finger spacing; The sum of the second finger width and the second finger spacing is the second stripe period; the second stripe period ranges from 0.3 μm to 3.5 μm; A ratio of the second finger width to the second stripe period is a second duty cycle corresponding to the second finger; and the second duty cycle is in a range of 0.4 to 0.

65.

5. A surface acoustic wave resonator according to claim 4, characterized in that: Each of the second fingers has a second finger length extending along the first direction; The length of the second finger is determined according to the order of the second fingers in the second direction and the number of the plurality of second fingers.

6. A surface acoustic wave resonator according to claim 1, characterized in that: The interdigitated structure includes a plurality of first fingers and a plurality of opposing spacings formed between the plurality of second fingers; The plurality of opposing intervals are parallel to each other in the second direction and are staggeredly distributed around a central axis of the interdigitated structure.

7. A surface acoustic wave resonator according to claim 6, characterized in that: The spacing range of the opposing spacing is 0.2 μm to 10.5 μm.

8. A surface acoustic wave resonator according to claim 1, characterized in that: The reflective grating includes a plurality of reflective grating strips arranged in parallel in the first direction; In the first direction, each reflective grating has a grating width; the grating width is determined according to the first stripe period and / or the second stripe period.

9. A surface acoustic wave resonator according to claim 8, characterized in that: Any two adjacent reflective gratings form a grating spacing in the first direction; the grating spacing is determined according to the first strip period and / or the second strip period.

10. The surface acoustic wave resonator according to claim 8, characterized in that: The size of each of the reflective gratings in the second direction is greater than or equal to the size of the interdigital structure in the second direction.

11. The surface acoustic wave resonator according to claim 8, characterized in that: The plurality of reflective gratings, the first finger bars and the second finger bars form a plurality of reflective holes; The plurality of reflective holes are arranged at first intervals in the first direction, and are arranged at second intervals in the second direction.

12. A surface acoustic wave resonator according to claim 11, characterized in that: The multiple reflective holes have the same shape, and are all rectangular or rhombus-shaped; When the shape of the multiple reflective holes is rhombus, the angle between any of the reflective grating strips and the first finger strips and / or the second finger strips in the first direction ranges from 60° to 85°.

13. A filter, characterized in that: The invention comprises a surface acoustic wave resonator as claimed in any one of claims 1 to 12.

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