CN118353413B - Surface acoustic wave resonator - Google Patents

Abstract

The invention discloses a surface acoustic wave resonator, which comprises a piezoelectric layer and an electrode layer positioned on the piezoelectric layer; the surface acoustic wave resonator further comprises a first reflecting grating region, a second reflecting grating region, a first electrode region, a second electrode region and a third electrode region, wherein the first reflecting grating, the second reflecting grating, the first interdigital electrode, the second interdigital electrode and the third interdigital electrode are arranged in an array; along the second direction, the first interdigital electrode has a first height H1, the second interdigital electrode has a second height H2, the third interdigital electrode has a third height H3, and the first reflective grating has a fourth height H4; the second reflecting grating has a fifth height H5; h1 is more than H2 and less than H4, and H3 is more than H2 and less than H5; or H4 is less than H2 and less than H1, and H5 is less than H2 and less than H3, so that stray effect near the series resonance point can be reduced, ripple near the series resonance point can be reduced, and the integral insertion loss in the passband of the SAW filter can be effectively reduced.

Description

Surface acoustic wave resonator

Technical Field

The invention relates to the technical field of radio frequency devices, in particular to a surface acoustic wave resonator.

Background

In recent years, with the falling to the ground and popularization of the fifth generation mobile communication technology (5G), the development of the radio frequency front end is crucial as a basic link of the mobile terminal communication in the 5G era. The saw filter is one of the key components of the current rf front end, and its operating frequency and in-band relative insertion loss (i.e., insertion loss) have a significant impact on the processing of the transmit signal and the receive signal of the rf front end.

The surface acoustic wave filter is composed of a plurality of surface acoustic wave resonators (SAW) in series-parallel connection, the SAW is mainly formed by periodically arranging interdigital electrodes on the upper surface of a piezoelectric layer, the acoustic wave in the form of standing wave generated by inverse piezoelectric effect propagates along the direction perpendicular to the electrodes, and the frequency is mainly determined by the spacing between the interdigital electrodes and the thickness of the electrodes.

The electrode material of the surface acoustic wave device has a larger influence on the performance, namely the mass loading effect of the electrode. Changing the electrode thickness affects the elastic coefficient of the resonator, thereby reducing the propagation speed of sound waves in the resonator, so that the resonance frequency is different at different electrode thicknesses under the condition of constant wavelength. In the prior art, the thicknesses of electrodes in the surface acoustic wave resonator are consistent, so that the propagation intensity of each part of the interdigital area to acoustic signals is the same, and more ripples are caused by diffraction effects between the electrodes, so that passband insertion loss is larger.

Fig. 1 is a schematic diagram of admittance of a prior art surface acoustic wave resonator, in which the abscissa is frequency f (unit: MHz), the ordinate is admittance Y (unit: dB), the solid line is an admittance curve, and the broken line is a conductance curve (admittance Y is formed by conductance G as a real part and susceptance B as an imaginary part, i.e., y=g+jb), as shown in fig. 1, in the current surface acoustic wave filter, there are some parasitic modes around frequency fr lower than the series resonance point Q0 (the point with the maximum admittance value) of the series resonator, which generally causes some ripple on the left side of the pass band of the filter (i.e., the left side of the series resonance point Q0) in the figure, i.e., ripple on the left side of the series resonance point Q0 in the figure, which is caused by diffraction effects between electrodes, thereby causing the insertion loss of the pass band to become large.

Disclosure of Invention

The invention provides a surface acoustic wave resonator which is used for inhibiting ripples existing on the left side of the frequency of a resonance point and improving the insertion loss of the whole filter.

According to an aspect of the present invention, there is provided a surface acoustic wave resonator comprising: a piezoelectric layer and an electrode layer on the piezoelectric layer;

the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region;

the first reflective gate region, the first electrode region, the second electrode region, the third electrode region and the second reflective gate region are sequentially arranged along a first direction;

In the first reflective grating region, the electrode layer comprises first reflective gratings arranged in an array; the electrode layer comprises second reflecting grids arranged in an array in the second reflecting grid region; the electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; the electrode layer comprises second interdigital electrodes arranged in an array in the second electrode region; in the third electrode region, the electrode layer comprises third finger electrodes arranged in an array;

In a second direction, the first interdigital electrode has a first height H1, the second interdigital electrode has a second height H2, the third interdigital electrode has a third height H3, and the first reflective grating has a fourth height H4; the second reflective grating has a fifth height H5;

H1 is more than H2 and less than H4, and H3 is more than H2 and less than H5; or H4 < H2 < H1 and H5 < H2 < H3;

Wherein the first direction is perpendicular to the lamination direction of the piezoelectric layer and the electrode layer, and the second direction is parallel to the lamination direction of the piezoelectric layer and the electrode layer.

Optionally, the fourth height H4 and the fifth height H5 satisfy: h4 =h5.

Optionally, the first height H1 and the third height H3 satisfy: h1 =h3.

Optionally, the first electrode region includes N1 first electrode regions; the third electrode region comprises N2 third electrode regions; n1 is more than or equal to 2, N2 is more than or equal to 2, and N1 and N2 are integers;

the heights of the first interdigital electrodes positioned in different first electrode subareas are different; and/or the heights of third finger electrodes located in different third electrode subregions are different.

Alternatively to this, the method may comprise, n1=n2;

along the first direction, the lengths of the first electrode sub-regions are equal, the lengths of the third electrode sub-regions are equal, and the lengths of the first electrode sub-regions are equal to the lengths of the third electrode sub-regions.

Optionally, the second electrode region includes a midline, and along the first direction, the second electrode region is symmetrical about the midline;

Along the first direction, the height of each first interdigital electrode in each first electrode subarea and the height of each third interdigital electrode in each third electrode subarea are symmetrical with respect to the central line of the second electrode area.

Optionally, the first reflective gate area includes N3 first reflective gate areas; the second reflective gate region comprises N4 second reflective gate regions; n3 is more than or equal to 2, N4 is more than or equal to 2, and N3 and N4 are integers;

The heights of the first reflecting grids positioned in different first reflecting grid subareas are different; and/or the heights of the second reflective gratings positioned in different second reflective grating sub-areas are different.

Alternatively to this, the method may comprise, n3=n4;

Along the first direction, the lengths of the first reflective gate regions are equal, the lengths of the second reflective gate regions are equal, and the lengths of the first reflective gate regions are equal to the lengths of the second reflective gate regions.

Optionally, the second electrode region includes a midline, and along the first direction, the second electrode region is symmetrical about the midline;

the height of each first reflecting grating in each first reflecting grating region and the height of each second reflecting grating in each second reflecting grating region are symmetrical with respect to the center line of the second electrode region along the first direction.

According to another aspect of the present invention, there is provided a surface acoustic wave resonator comprising: a piezoelectric layer and an electrode layer on the piezoelectric layer;

the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region;

the first reflective gate region, the first electrode region, the second electrode region, the third electrode region and the second reflective gate region are sequentially arranged along a first direction;

in the first reflective grating region, the electrode layer comprises first reflective gratings arranged in an array; the height of each first reflecting grating is increased or decreased along the first direction;

The electrode layer comprises second reflecting grids arranged in an array in the second reflecting grid region; the height of each second reflecting grating is increased or decreased along the first direction;

The electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; the height of each first interdigital electrode increases or decreases along the first direction;

The electrode layer comprises second interdigital electrodes arranged in an array in the second electrode region; the heights of the second interdigital electrodes are the same;

in the third electrode region, the electrode layer comprises third finger electrodes arranged in an array; the height of each third finger electrode is increased or decreased along the first direction;

wherein the first direction is perpendicular to a lamination direction of the piezoelectric layer and the electrode layer.

In the embodiment, the surface acoustic wave resonator comprises a piezoelectric layer and an electrode layer positioned on the piezoelectric layer, and the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region, so that the electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; in the second electrode area, the electrode layer includes the second interdigital electrode that the array set up, in the third electrode area, the electrode layer includes the third interdigital electrode that the array set up, can make the first interdigital electrode that array was arranged on piezoelectric layer and the piezoelectric layer, second interdigital electrode and third interdigital electrode realize the acoustoelectric conversion, and be located the first reflection grid that first reflection grid area array was arranged and be located the first reflection grid that second reflection grid area array was arranged can reduce signal loss, improve signal transmission's accuracy, and set up along second direction Y, first height H1 of first interdigital electrode B11, second height H2 of second interdigital electrode B21, third height H3 of third interdigital electrode B31, fourth height H4 of first reflection grid A11 and fifth height H5 of second reflection grid A21 satisfy: h1 < H2 < H4 and H3 < H2 < H5, or: h4 is less than H2 and less than H1, H5 is less than H2 and less than H3, so that the spurious effect near the series resonance point can be reduced under the condition that the overall performance of the surface acoustic wave resonator is not changed, namely the ripple near the series resonance point is reduced, and the overall insertion loss in the passband of the surface acoustic wave filter formed by a plurality of surface acoustic wave resonators can be effectively reduced.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of the admittance of a prior art SAW resonator;

Fig. 2 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 4 is another cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 5 is a schematic diagram of admittance of a SAW resonator provided by an embodiment of the present invention;

fig. 6 is a schematic structural diagram of another surface acoustic wave resonator according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view taken along E3-E4 of FIG. 6;

FIG. 8 is another cross-sectional view taken along E3-E4 of FIG. 6;

FIG. 9 is a schematic diagram of admittance of another SAW resonator provided by an embodiment of the present invention;

FIG. 10 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 11 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 12 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 13 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 14 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 15 is a further cross-sectional view taken along E1-E2 of FIG. 2;

FIG. 16 is a further cross-sectional view taken along E3-E4 of FIG. 6;

FIG. 17 is a further cross-sectional view taken along E3-E4 of FIG. 6;

fig. 18 is a schematic diagram of an insertion loss of a surface acoustic wave filter according to an embodiment of the present invention;

fig. 19 is an enlarged partial schematic view of fig. 18.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Fig. 2 is a schematic structural view of a surface acoustic wave resonator according to an embodiment of the present invention, fig. 3 is a cross-sectional view taken along line E1-E2 in fig. 2, and fig. 4 is another cross-sectional view taken along line E1-E2 in fig. 2, and referring to fig. 2, fig. 3 and fig. 4 in combination, the surface acoustic wave resonator includes: a piezoelectric layer 10 and an electrode layer 20 on the piezoelectric layer 10; the surface acoustic wave resonator further comprises a first reflecting gate region A1, a second reflecting gate region A2, a first electrode region B1, a second electrode region B2 and a third electrode region B3; the first reflective gate region A1, the first electrode region B1, the second electrode region B2, the third electrode region B3 and the second reflective gate region A2 are sequentially arranged along the first direction X; in the first reflective grating region A1, the electrode layer 20 includes first reflective gratings a11 arranged in an array; in the second reflective grating area A2, the electrode layer 20 includes second reflective gratings a21 arranged in an array; in the first electrode region B1, the electrode layer 20 includes first interdigital electrodes B11 arranged in an array; in the second electrode region B2, the electrode layer 20 includes second interdigital electrodes B21 arranged in an array; in the third electrode region B3, the electrode layer 20 includes third finger electrodes B31 arranged in an array; along the second direction Y, the first interdigital electrode B11 has a first height H1, the second interdigital electrode B21 has a second height H2, the third interdigital electrode B31 has a third height H3, and the first reflective grating a11 has a fourth height H4; the second reflective grating a21 has a fifth height H5; h1 < H2 < H4 and H3 < H2 < H5 (see FIG. 3); or H4 < H2 < H1 and H5 < H2 < H3 (see FIG. 4); wherein the first direction X is perpendicular to the lamination direction of the piezoelectric layer 10 and the electrode layer 20, and the second direction Y is parallel to the lamination direction of the piezoelectric layer 10 and the electrode layer 20.

Among them, the piezoelectric layer 10 may be made of piezoelectric materials such as piezoelectric crystals and piezoelectric ceramics, and in an exemplary embodiment, the material for making the piezoelectric layer 10 may include one or more of aluminum nitride (AlN), doped aluminum nitride, zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3), quartz (Quartz), potassium niobate (KNbO 3), and lithium tantalate (LiTaO 3). In an alternative embodiment, the piezoelectric layer 10 may be a single-layer structure, for example, the piezoelectric layer 10 may be a lithium niobate film; in another alternative embodiment, the piezoelectric layer 10 may also be a multilayer structure, such as a piezoelectric thin film composite structure, or the like. The piezoelectric layer 10 may be a composite structure of lithium tantalate piezoelectric film/silicon dioxide/silicon substrate, for example. The above description is merely illustrative of the piezoelectric layer 10, and is not intended to limit the piezoelectric layer 10.

The first reflective gate region A1, the first electrode region B1, the second electrode region B2, the third electrode region B3 and the second reflective gate region A2 are arranged in sequence along the first direction X, and the first interdigital electrode B11, the second interdigital electrode B21 and the third interdigital electrode B31 which are arranged in an array are respectively arranged in the first electrode region B1, the second electrode region B2 and the third electrode region B3, so that the piezoelectric layer 10 and the first interdigital electrode B11, the second interdigital electrode B21 and the third interdigital electrode B31 which are arranged in an array on the piezoelectric layer 10 can realize the acousto-electric conversion. In addition, the first reflective grating region A1 and the second reflective grating region A2 are disposed along the first direction X and are respectively located at two opposite sides of the region formed by the first electrode region B1, the second electrode region B2 and the third electrode region B3, so that the first reflective grating a11 located in the array arrangement of the first reflective grating region A1 and the second reflective grating a21 located in the array arrangement of the second reflective grating region A2 can define a signal transmission region, that is, signals are limited to be transmitted in the first electrode region B1, the second electrode region B2 and the third electrode region B3 located between the first reflective grating region A1 and the second reflective grating region A2, signal loss can be reduced, and signal transmission accuracy is improved. Wherein the first direction X is perpendicular to the lamination direction of the piezoelectric layer 10 and the electrode layer 20.

On the basis of this, the second direction Y is set parallel to the lamination direction of the piezoelectric layer 10 and the electrode layer 20, and the first height H1 of the first interdigital electrode B11, the second height H2 of the second interdigital electrode B21, the third height H3 of the third interdigital electrode B31, the fourth height H4 of the first reflective grating a11, and the fifth height H5 of the second reflective grating a21 are set so as to satisfy: h1 < H2 < H4 and H3 < H2 < H5, or: h4 < H2 < H1 and H5 < H2 < H3. The second height H2 of the second interdigital electrode B21 located in the middle region is the middle height of the heights, so that interdigital electrode pairs with different heights have different transmission intensities, diffraction effects between the electrodes can be reduced, stray effects near the series resonance point can be reduced under the condition that the overall performance of the surface acoustic wave resonator is not changed, namely ripple waves near the series resonance point are reduced, and the overall insertion loss in the passband of the surface acoustic wave filter formed by a plurality of surface acoustic wave resonators can be effectively reduced.

It can be appreciated that in this embodiment, the heights of the interdigital electrodes located in the same electrode region are the same, and the heights of the reflective grids located in the same reflective grid region are the same.

In the embodiment, the surface acoustic wave resonator comprises a piezoelectric layer and an electrode layer positioned on the piezoelectric layer, and the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region, so that the electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; in the second electrode area, the electrode layer includes the second interdigital electrode that the array set up, in the third electrode area, the electrode layer includes the third interdigital electrode that the array set up, can make the first interdigital electrode that array was arranged on piezoelectric layer and the piezoelectric layer, second interdigital electrode and third interdigital electrode realize the acoustoelectric conversion, and be located the first reflection grid that first reflection grid area array was arranged and be located the first reflection grid that second reflection grid area array was arranged can reduce signal loss, improve signal transmission's accuracy, and set up along second direction Y, first height H1 of first interdigital electrode B11, second height H2 of second interdigital electrode B21, third height H3 of third interdigital electrode B31, fourth height H4 of first reflection grid A11 and fifth height H5 of second reflection grid A21 satisfy: h1 < H2 < H4 and H3 < H2 < H5, or: h4 is less than H2 and less than H1, H5 is less than H2 and less than H3, and can reduce diffraction effect between electrodes under the condition of not changing the overall performance of the surface acoustic wave resonator, thereby reducing stray effect near a series resonance point, namely reducing ripple near the series resonance point, and effectively reducing the overall insertion loss of a passband.

Optionally, referring to fig. 3, the fourth height H4 and the fifth height H5 satisfy: h4 =h5. That is, the fourth height H4 of the first reflective grating a11 is set to be equal to the fifth height H5 of the second reflective grating a21, so that the fourth height H4 of the first reflective grating a11 in the first reflective grating region A1 and the fifth height H5 of the second reflective grating a21 in the second reflective grating region A2 are symmetrical with respect to the center line L of the second electrode region B2, and the stray effect near the series resonance point can be further reduced. Wherein, along the first reverse direction X, the length of the second electrode region B2 is symmetrical about the center line L.

Optionally, with continued reference to fig. 3, the first height H1 and the third height H3 satisfy: h1 =h3. That is, the first height H1 of the first interdigital electrode B11 is set to be equal to the third height H3 of the third interdigital electrode B31, so that the first height H1 of the first interdigital electrode B11 in the first electrode region B1 and the third height H3 of the third interdigital electrode B31 in the third electrode region B3 are symmetrical with respect to the center line L of the second electrode region B2, and the spurious effect near the series resonance point can be further reduced.

Fig. 5 is an admittance diagram of a surface acoustic wave resonator according to an embodiment of the present invention, where: the abscissa is the frequency f (unit: MHz) and the ordinate is the admittance Y (unit: dB). Referring to fig. 2,3, 4 and 5 in combination, the height of the second interdigital electrode B21 in the second electrode region B2, the height of the first interdigital electrode B11 in the first electrode region B1 and the first reflective gate a11 in the first reflective gate region A1 are set to be different, the height of the second interdigital electrode B21 in the second electrode region B2, the height of the third interdigital electrode B31 in the third electrode region B3 and the second reflective gate a21 in the second reflective gate region A2 are set to be different, and the fourth height H4 and the fifth height H5 are set to satisfy h4=h5, the first height H1 and the third height H3 satisfy h1=h3, i.e., the height of the first interdigital electrode B11 in the first reflective gate region A1 and the first reflective gate region B11 in the second reflective gate region A3 and the height of the third interdigital electrode B31 in the third electrode region B3 are set to be symmetrical with respect to the center line L, according to simulation, it can be determined that the simulation curve Lc 2of the surface acoustic wave resonator in the prior art has larger ripple intensity near the series resonance point Q1, but the simulation curve Lc1 of the surface acoustic wave resonator in the embodiment of the invention has obviously reduced ripple intensity near the series resonance point Q1, that is, compared with the prior art, the surface acoustic wave resonator provided by the embodiment of the invention can further reduce the stray effect (i.e., ripple) near the series resonance point Q1, can inhibit the parasitic mode existing on the left side of the series resonance point Q1, so that the curve on the left side of the series resonance point Q1 is relatively smooth, the influence of the ripple on the left side of the pass band is reduced, and the integral insertion loss of the filter is improved.

In a preferred embodiment, the lengths of the first reflective grating A1 and the second reflective grating A2 may be equal along the first direction X, and the number of first reflective gratings a11 in the first reflective grating A1 and the number of second reflective gratings a21 in the second reflective grating A2 may be equal. And the lengths of the first electrode region B1 and the third electrode region B3 may be equal in the first direction X, and the number of the first interdigital electrodes B11 in the first electrode region B1 and the number of the third interdigital electrodes B31 in the third electrode region B3 may be equal. And the number of second interdigital electrodes B21 in the second electrode region B2 may be set to be much larger than the number of first interdigital electrodes B11 in the first electrode region B1 (i.e., simultaneously to be much larger than the number of third interdigital electrodes B31 in the third electrode region B3), for example, eighty second interdigital electrodes B21 are included in the second electrode region B2, and 10 first interdigital electrodes B11 are included in the first electrode region B1. Through verification, the stray effect near the series resonance point can be effectively reduced by the arrangement, namely, ripple waves near the series resonance point can be effectively reduced, and therefore, the overall insertion loss of the passband can be effectively reduced.

Alternatively, fig. 6 is a schematic structural diagram of another surface acoustic wave resonator according to an embodiment of the present invention, fig. 7 is a cross-sectional view taken along line E3-E4 in fig. 6, fig. 8 is another cross-sectional view taken along line E3-E4 in fig. 6, and referring to fig. 6, fig. 7 and fig. 8 in combination, the first electrode region B1 includes N1 first electrode sub-regions B1a; the third electrode region B3 includes N2 third electrode regions B3a; n1 is more than or equal to 2, N2 is more than or equal to 2, and N1 and N2 are integers; the heights of the first interdigital electrodes B11 positioned in different first electrode sub-areas B1a are different; and/or the third finger electrodes B31 located in different third electrode sub-areas B3a are different in height.

Specifically, the first electrode area B1 may be divided into N1 first electrode sub-areas B1a, and the heights of the first interdigital electrodes B11 located in different first electrode sub-areas B1a may be set to be different, for example, the heights of the first interdigital electrodes B11 of the first electrode sub-areas B1a along the first direction X may be set to be sequentially decreased (as shown in fig. 8), or the heights of the first interdigital electrodes B11 of the first electrode sub-areas B1a along the first direction X may be set to be sequentially increased (as shown in fig. 7), which may also effectively reduce the ripple near the series resonance point through the test. Alternatively, the third electrode area B3 may include N2 third electrode sub-areas B3a, and the heights of the third finger electrodes B31 located in different third electrode sub-areas B3a are made different, for example, the heights of the third finger electrodes B31 of the respective third electrode sub-areas B3a along the first direction X may be sequentially decreased (as shown in fig. 7), or the heights of the third finger electrodes B31 of the respective third electrode sub-areas B3a along the first direction X may be sequentially increased (as shown in fig. 8), which may also effectively reduce the ripple near the series resonance point. Or the heights of the first interdigital electrodes B11 positioned in different first electrode subareas B1a are different, and the heights of the third interdigital electrodes B31 positioned in different third electrode subareas B3a are different at the same time, so as to achieve the effect of reducing ripple waves near the series resonance point.

It should be understood that in the present embodiment, the heights of the interdigital electrodes located in the same electrode sub-region are the same, and it should be noted that, in the drawings, only the first electrode region B1 including two first electrode sub-regions B1a and the third electrode region B3 including two third electrode sub-regions B3a are shown by way of example, but not limited thereto.

Optionally, with continued reference to fig. 6, 7 and 8, n1=n2, and along the first direction, the lengths of the first electrode sub-regions B1a are equal, the lengths of the third electrode sub-regions B3a are equal, and the lengths of the first electrode sub-regions B1a are equal to the lengths of the third electrode sub-regions B3 a.

Specifically, the number N1 of the first electrode sub-regions B1a in the first electrode region B1 and the number N2 of the third electrode sub-regions B3a in the third electrode region B3 may be set to be equal, and the lengths of the respective first electrode sub-regions B1a along the first direction X may be set to be equal, the lengths of the respective third electrode sub-regions B3a may be set to be equal, and the lengths of the first electrode sub-regions B1a and the third electrode sub-regions B3a may be set to be equal. In this way, the pitches of the interdigital electrodes in the respective regions are identical, and the number of the first interdigital electrodes B11 in each first electrode subregion B1a and the number of the third interdigital electrodes B31 in each third electrode subregion B3a are identical, so that since n1=n2, the number of the first interdigital electrodes B11 in the first electrode region B1 and the number of the third interdigital electrodes B31 in the third electrode region B3 can be made equal, the arrangement (including the height and the number) of the first interdigital electrodes B11 in the first electrode region B1 and the arrangement of the third interdigital electrodes B31 in the third electrode region B3 can be made relatively symmetrical, and the ripple effect in the vicinity of the series resonance point can be further reduced.

Optionally, with continued reference to fig. 6, 7 and 8, the second electrode region B2 includes a centerline L, and along the first direction X, the length of the second electrode region B2 is symmetrical about the centerline L; along the first direction X, the height of each first interdigital electrode B11 in each first electrode sub-region B1a and the height of each third interdigital electrode B31 in each third electrode sub-region B3a are symmetrical with respect to the center line L of the second electrode region B2.

Specifically, the height of each first interdigital electrode B11 in each first electrode sub-region B1a and the height of each third interdigital electrode B31 in each third electrode sub-region B3a may be set to be symmetrical with respect to the center line L of the second electrode region B2, for example, the height of each first interdigital electrode B11 in each first electrode sub-region B1a is set to decrease in sequence along the first direction X, and the height of each third interdigital electrode B31 in each third electrode sub-region B3a increases in sequence along the first direction X (as shown in fig. 8). Or the heights of the first interdigital electrodes B11 of the first electrode sub-areas B1a are sequentially increased along the first direction X, and the heights of the third interdigital electrodes B31 of the third electrode sub-areas B3a are sequentially decreased along the first direction X (as shown in fig. 7). And along the first direction X, the height of the first interdigital electrode B11 in the first electrode sub-region B1a in the first electrode region B1 is equal to the height of the third interdigital electrode B31 in the last third electrode sub-region B3a in the third electrode region B3, the height of the first interdigital electrode B11 in the second first electrode sub-region B1a in the first electrode region B1 is equal to the height of the third interdigital electrode B31 in the last third electrode sub-region B3a in the third electrode region B3 … …, and so on, so that the arrangement (including the height and the number) of the first interdigital electrode B11 in the first electrode region B1 and the arrangement of the third interdigital electrode B31 in the third electrode region B3 are completely symmetrical, and the ripple effect near the series resonance point can be further reduced.

Optionally, with continued reference to fig. 6,7 and 8, the first reflective gate area A1 includes N3 first reflective gate areas A1a; the second reflective gate area A2 includes N4 second reflective gate areas A2a; n3 is more than or equal to 2, N4 is more than or equal to 2, and N3 and N4 are integers; the heights of the first reflective gratings A11 positioned in different first reflective grating sub-areas A1a are different; and/or the heights of the second reflective gratings a21 located at different second reflective grating sub-areas A2a are different.

Specifically, the first reflective gate area A1 may include N3 first reflective gate areas A1a, and heights of the first reflective gates a11 located in different first reflective gate areas A1a may be set to be different, for example, the heights of the first interdigital electrodes a11 of the first reflective gate areas A1a along the first direction X may be set to be sequentially decreased (as shown in fig. 7), or the heights of the first reflective gates a11 of the first reflective gate areas A1a along the first direction X may be set to be sequentially increased (as shown in fig. 8), which may also effectively reduce the ripple near the series resonance point through test. Alternatively, the second reflective grating area A2 may include N4 second reflective grating areas A2a, and the heights of the second reflective gratings a21 located in different second reflective grating areas A2a are different, for example, the heights of the second reflective gratings a21 of the second reflective grating areas A2a in the first direction X may be sequentially decreased (as shown in fig. 8), or the heights of the second reflective gratings a22 of the second reflective grating areas A2a in the first direction X may be sequentially increased (as shown in fig. 7), which may also effectively reduce the ripple near the series resonance point. Or the heights of the first reflective grids A11 positioned in different first reflective grid sub-areas A1a are different, and the heights of the second reflective grids A22 positioned in different second reflective grid sub-areas A2a are different, so as to achieve the effect of reducing ripple waves near the series resonance point.

It should be understood that in the present embodiment, the heights of the reflective gratings located in the same reflective grating region are the same, and it should be noted that, in the drawings, only the first reflective grating region A1 including two first reflective grating regions A1a and the second reflective grating region A2 including two second reflective grating regions A2a are shown by way of example, but not limited thereto.

Alternatively, with continued reference to fig. 6, 7 and 8, n3=n4; along the first direction X, the lengths of the first reflective gate areas A1a are equal, the lengths of the second reflective gate areas A2a are equal, and the lengths of the first reflective gate areas A1a are equal to the lengths of the second reflective gate areas A2 a.

Specifically, the number N3 of the first reflective gate areas A1a in the first reflective gate area A1 may be equal to the number N4 of the second reflective gate areas A2a in the second reflective gate area A2, and the lengths of the first reflective gate areas A1a and the second reflective gate areas A2a are equal along the first direction X. In this way, the number of the first reflective gratings a11 in each first reflective grating area A1a and the number of the second reflective gratings a22 in each second reflective grating area A2a are equal, so that the number of the first reflective gratings a11 in the first reflective grating area A1 and the number of the second reflective gratings a21 in the second reflective grating area A3 can be equal due to n3=n4, the arrangement (including height and number) of the first reflective gratings a11 in the first reflective grating area A1 and the arrangement of the second reflective gratings a21 in the second reflective grating area A2 can be symmetrical, and the ripple effect near the series resonance point can be further reduced.

Optionally, with continued reference to fig. 6, 7 and 8, the second electrode region B2 includes a centerline L, and along the first direction X, the length of the second electrode region B2 is symmetrical about the centerline L; the height of each first reflective grating a11 in each first reflective grating region A1a and the height of each second reflective grating a21 in each second reflective grating region A2a are symmetrical with respect to the center line L of the second electrode region B2 along the first direction X.

Specifically, the height of each first reflective grating a11 in each first reflective grating area A1a and the height of each second reflective grating a21 in each second reflective grating area A2a may be set to be symmetrical with respect to the center line L of the second electrode area B2, for example, the height of the first reflective grating a11 in which each first reflective grating area A1a is set decreases in sequence along the first direction X, and the height of the second reflective grating a21 in each second reflective grating area A2a increases in sequence along the first direction X (as shown in fig. 7). Or the heights of the first reflective grids a11 of the first reflective grid sub-areas A1a are sequentially increased along the first direction X, and the heights of the second reflective grids a21 of the second reflective grid sub-areas A2a are sequentially decreased along the first direction X (as shown in fig. 8). And along the first direction X, the height of the first reflective grating a11 in the first reflective grating area A1a in the first reflective grating area A1 is equal to the height of the second reflective grating a21 in the last second reflective grating area A2a in the second reflective grating area A2, the height of the first reflective grating a11 in the second first reflective grating area A1a in the first reflective grating area A1 is equal to the height of the second reflective grating a21 in the last second reflective grating area A2a in the second reflective grating area A2 … …, and so on, so that the arrangement (including the height and the number) of the first reflective grating a11 in the first reflective grating area A1 and the arrangement of the second reflective grating a21 in the second reflective grating area A2 are completely symmetrical, and the ripple effect near the series resonance point can be further reduced.

Optionally, fig. 9 is a schematic diagram of admittance of another surface acoustic wave resonator according to an embodiment of the present invention, where: the abscissa is the frequency f (unit: MHz). Referring to fig. 6, 7 and 9 in combination (or fig. 6, 8 and 9 in combination), it is also possible to provide that the first electrode region B1 includes N1 first electrode regions B1a, the third electrode region B3 includes N2 third electrode regions B3a, the first reflective gate region A1 includes N3 first reflective gate regions A1a and the second reflective gate region A2 includes N4 second reflective gate regions A2a, and to provide n1=n2, n3=n4; along the first direction X, the length of the first electrode sub-region B1a is equal to the length of the third electrode sub-region B3a, and the length of the first reflective gate sub-region A1a is equal to the length of the second reflective gate sub-region A2 a; and along the first direction X, the height of each first interdigital electrode B11 in each first electrode sub-region B1a and the height of each third interdigital electrode B31 in each third electrode sub-region B3a are symmetrical with respect to the central line L of the second electrode region B2, and the height of each first reflective grating a11 in each first reflective grating sub-region A1a and the height of each second reflective grating a21 in each second reflective grating sub-region A2a are symmetrical with respect to the central line L of the second electrode region B2. At this time, the ripple intensity of the simulation curve Lc4 of the surface acoustic wave resonator in the prior art near the series resonance point Q1 is larger, but the ripple intensity of the simulation curve Lc3 of the surface acoustic wave resonator in the embodiment of the present invention near the series resonance point Q1 is obviously reduced, so that the spurious effect near the series resonance point Q1 can be effectively reduced, the parasitic mode existing on the left side of the series resonance point Q1 can be suppressed, the curve on the left side of the series resonance point Q1 is relatively smooth, the influence of the ripple at this point on the left side of the passband is reduced, and the insertion loss of the whole filter is improved.

Based on the same inventive concept, the embodiment of the present invention further provides another surface acoustic wave resonator, fig. 10 is a further cross-sectional view along E1-E2 of fig. 2, and referring to fig. 2 and 10 in combination, the surface acoustic resonator includes a piezoelectric layer 10 and an electrode layer 20 on the piezoelectric layer 10; the surface acoustic wave resonator further comprises a first reflecting gate region A1, a second reflecting gate region A2, a first electrode region B1, a second electrode region B2 and a third electrode region B3; the first reflective gate region A1, the first electrode region B1, the second electrode region B2, the third electrode region B3 and the second reflective gate region A2 are sequentially arranged along the first direction X; in the first reflective grating region A1, the electrode layer 20 includes first reflective gratings a11 arranged in an array; the height of each first reflecting grating A11 is increased or decreased along the first direction X; in the second reflective grating area A2, the electrode layer 20 includes second reflective gratings a21 arranged in an array; the height of each second reflecting grating A21 is increased or decreased along the first direction X; in the first electrode region B1, the electrode layer 20 includes first interdigital electrodes B11 arranged in an array; the height of each first interdigital electrode B11 increases or decreases along the first direction X; in the second electrode region B2, the electrode layer 20 includes second interdigital electrodes B21 arranged in an array; the heights of the second interdigital electrodes B21 are the same; in the third electrode region B3, the electrode layer 20 includes third finger electrodes B31 arranged in an array; the height of each third finger electrode B31 is increased or decreased along the first direction X; wherein the first direction X is perpendicular to the lamination direction of the piezoelectric layer 10 and the electrode layer 20. It is understood that the heights of the first interdigital electrode B11, the second interdigital electrode B21, the third interdigital electrode B31, the first reflective grating a11, and the second reflective grating a21 all extend in a second direction Y, which is parallel to the lamination direction of the piezoelectric layer 10 and the electrode layer 20.

Specifically, the heights of the interdigital electrodes located in the same electrode region may also be different, and the heights of the reflective grids located in the same reflective grid region may also be different. It is understood that the height of the interdigital electrode and the height of the reflective grating refer to a height extending in the second direction Y, which is parallel to the lamination direction of the piezoelectric layer 10 and the electrode layer 20. The heights of the first reflection grids A11 in the first reflection grid region A1 are increased or decreased along the first direction X, the heights of the second reflection grids A21 in the second reflection grid region A2 are increased or decreased along the first direction X, the heights of the first interdigital electrodes B11 in the first electrode region B1 are increased or decreased along the first direction X, and the heights of the third interdigital electrodes B31 in the third electrode region B3 are increased or decreased along the first direction X, so that the interdigital electrodes with different heights have different transmission intensities on signals, diffraction effects among the electrodes can be reduced, stray effects near serial resonance points can be reduced under the condition that the overall performance of the SAW resonator is not changed, namely ripples near the serial resonance points can be reduced, and the insertion loss of the whole passband can be effectively reduced.

The second electrode area B2 is a main electrode setting area of the surface acoustic wave resonator, and preferably, the area of the second electrode area B2 is larger than the areas of the first electrode area B1, the third electrode area B3, the first reflective gate area A1 and the second reflective gate area A2, so that the number of second interdigital electrodes B21 in the second electrode area B2 is far greater than the number of interdigital electrodes in the first electrode area B1 and the third electrode area B3, and far greater than the number of reflective gates in the first reflective gate area A1 and the second reflective gate area A2.

Optionally, the array of the first interdigital electrode B11 in the first electrode region B1 and the array of the third interdigital electrode B31 in the third electrode region B3 are the same, and the array of the first reflective grating a11 in the first reflective grating region A1 and the array of the second reflective grating a21 in the second reflective grating region A2 are the same. Referring to fig. 2 and 10, the length of the second electrode region B2 is symmetrical about the center line L in the first direction X. On the basis, the height of each first reflective grating a11 in the first reflective grating region A1 may be set to decrease along the first direction X, the height of each second reflective grating a21 in the second reflective grating region A2 may be set to increase along the first direction X, the height of each first interdigital electrode B11 in the first electrode region B1 may be set to increase along the first direction X, the height of each third interdigital electrode B31 in the third electrode region B3 may decrease along the first direction X, so that the height of each first reflective grating a11 in the first reflective grating region A1 may be symmetrical to each second reflective grating a21 in the second reflective grating region A2 about the center line L, and the height of each first interdigital electrode B11 in the first electrode region B1 and each third interdigital electrode B31 in the third electrode region B3 may be symmetrical to each other about the center line L, thereby further reducing diffraction effects between the electrodes, and further reducing overall insertion loss.

Or fig. 11 is a further cross-sectional view along the line E1-E2 in fig. 2, and referring to fig. 2 and 11 in combination, it is also possible to arrange that the height of each first reflective grating a11 in the first reflective grating region A1 increases along the first direction X, the height of each second reflective grating a21 in the second reflective grating region A2 decreases along the first direction X, the height of each first interdigital electrode B11 in the first electrode region B1 decreases along the first direction X, and the height of each third interdigital electrode B31 in the third electrode region B3 increases along the first direction X, so that the height of each first reflective grating a11 in the first reflective grating region A1 and the height of each second reflective grating a21 in the second reflective grating region A2 are symmetrical about the center line L, and the height of each first interdigital electrode B11 in the first electrode region B1 and the height of each third interdigital electrode B31 in the third electrode region B3 are symmetrical about the center line L, which can further reduce the diffraction effect between the electrodes as a whole, thereby further reducing the insertion loss between the electrodes.

For example, fig. 12 and 13 are further cross-sectional views of fig. 2 along E1-E2, referring to fig. 12, it is also possible to provide that the height of each first reflective grating a11 in the first reflective grating region A1 increases in the first direction X and the height of each first interdigital electrode B11 in the first electrode region B1 increases in the first direction X, and that the height of each second reflective grating a21 in the second reflective grating region A2 decreases in the first direction X and the height of each third interdigital electrode B31 in the third electrode region B3 decreases in the first direction X. Alternatively, referring to fig. 13, it is also possible to provide that the height of each first reflective grating a11 in the first reflective grating region A1 decreases in the first direction X and the height of each first interdigital electrode B11 in the first electrode region B1 decreases in the first direction X, and that the height of each second reflective grating a21 in the second reflective grating region A2 increases in the first direction X and the height of each third interdigital electrode B31 in the third electrode region B3 increases in the first direction X.

For example, referring to fig. 10, 11, 12 or 13, assuming that the height of each second interdigital electrode B21 in the second electrode region B2 is H2, the height of the first interdigital electrode B11 in the first electrode region B1 and the height of the third interdigital electrode B31 in the third electrode region B3 may be set to be between 0.98×h2 and H2 (may include 0.98×h2 and H2), and the height of the first reflective gate a11 in the first reflective gate region A1 and the height of the second reflective gate a21 in the second reflective gate region A2 may be set to be between H2 and 1.04×h2 (may include H2 and 1.04×h2), so that the height of each first reflective gate a11 and the second reflective gate a21 is greater than the height of the second interdigital electrode B21 in the second electrode region B2, and so that the height of the first interdigital electrode B11 and the second interdigital electrode B31 is less than the height of the second electrode B2 in the second electrode region B2, so that the height of each second interdigital electrode B21 in the second electrode region B1 and the second electrode B21 may not be further reduced, and so that the height of each second interdigital electrode B21 in the second electrode region B2 and the second electrode B2 may not be further reduced.

For example, fig. 14 is a further cross-sectional view taken along E1-E2 in fig. 2, referring to fig. 14, when the height of each first reflective gate a11 in the first reflective gate region A1 is symmetrical to the height of each second reflective gate a21 in the second reflective gate region A2 about the center line L, and the height of each first interdigital electrode B11 in the first electrode region B1 and each third interdigital electrode B31 in the third electrode region B3 is symmetrical to the center line L, the height of each first reflective gate a11 in the first reflective gate region A1 and the height of each second reflective gate a21 in the second reflective gate region A2 may be set to be between 0.98×h2 and H2 (may include 0.98×h2 and H2), and the height of each first interdigital electrode B11 in the first electrode region B1 and the height of each third interdigital electrode B31 in the third electrode region B3 may be set to be between H2 and 1.04×h2 (may include H2 and 1.04×h2). Only the height of each first reflective grating a11 in the first reflective grating region A1 decreases in the first direction X, the height of each second reflective grating a21 in the second reflective grating region A2 increases in the first direction X, the height of each first interdigital electrode B11 in the first electrode region B1 increases in the first direction X, and the height of each third interdigital electrode B31 in the third electrode region B3 decreases in the first direction X. In other possible embodiments, the heights of the electrodes and the reflective gratings are otherwise symmetrical about the midline L.

Fig. 15 is a further cross-sectional view taken along the line E1-E2 in fig. 2, referring to fig. 2 and 15 in combination, when the height of each first reflective grating a11 in the first reflective grating region A1 increases in the first direction X, the height of each second reflective grating a21 in the second reflective grating region A2 decreases in the first direction X, the height of each first interdigital electrode B11 in the first electrode region B1 decreases in the first direction X, the height of each third interdigital electrode B31 in the third electrode region B3 increases in the first direction X, the height of each first reflective grating a11 in the first reflective grating region A1 and the height of each second reflective grating a21 in the second reflective grating region A2 may be set to be between 0.98×h2 and H2 (may include 0.98×h2 and H2), and the height of each first interdigital electrode B11 in the first electrode region B1 and the height of each second interdigital electrode B31 in the third electrode region B3 may be set to be between 0.98×h2 and H2 (may include 0.04×h2 and H2).

Alternatively, fig. 16 is a further cross-sectional view along line E3-E4 of fig. 6, and referring to fig. 6 and 16 in combination, when the first reflective grating area A1 includes a plurality of first reflective grating areas A1a, the second reflective grating area A2 includes a plurality of second reflective grating areas A2a, the first electrode area B1 includes a plurality of first electrode areas B1a, and the third electrode area B3 includes a plurality of third electrode areas B3a, the height of each first reflective grating a11 located in the same first reflective grating area A1a may be increased or decreased along the first direction X, the height of each second reflective grating a21 located in the same second reflective grating area A2a may be increased or decreased along the first direction X, the height of the first finger electrode B11 located in the same first electrode area B1a may be increased or decreased along the first direction X, and the height of the first finger electrode B31 located in the same third electrode area B3a may be increased or decreased along the first direction X, which may reduce the same series spurious effects, that is, and may reduce the overall spurious effects near the resonance point.

For example, when the first reflective gate region A1 includes a plurality of first reflective gate regions A1a, the second reflective gate region A2 includes a plurality of second reflective gate regions A2a, the first electrode region B1 includes a plurality of first electrode regions B1a, and the third electrode region B3 includes a plurality of third electrode regions B3a, the number of first electrode regions B1a may be set to be the same as the number of third electrode regions B3a, and the number of first reflective gate regions A1a may be the same as the number of second reflective gate regions A2 a. On the basis of this, it is possible to provide the same electrode arrays in the respective first electrode subregions B1a and the respective third electrode subregions B3a, and to provide the same reflective gate arrays in the respective first reflective gate subregions A1a and the respective second reflective gate subregions A2 a. Therefore, the structure of the surface acoustic wave resonator is symmetrical about the central line L, so that the stray effect near the series resonance point is further reduced, namely the ripple wave near the series resonance point is reduced, and the insertion loss of the whole passband can be further reduced.

Further, the height of the first interdigital electrode B11 in each first electrode sub-area B1a and the height of the third interdigital electrode B31 in each third electrode sub-area B3a may be symmetrical about the central line L, and the height of the first reflective grating a11 in each first reflective grating sub-area A1a and the height of the second reflective grating a21 in each second reflective grating sub-area A2a may be symmetrical about the central line L, so that the structure of the surface acoustic wave resonator may be completely symmetrical about the central line L, which is beneficial to further reduce the stray effect near the series resonance point, that is, reduce the ripple near the series resonance point, and further reduce the insertion loss of the whole passband. For example, with continued reference to fig. 16, when the first reflective gate region A1 includes a plurality of first reflective gate regions A1a, the second reflective gate region A2 includes a plurality of second reflective gate regions A2a, the first electrode region B1 includes a plurality of first electrode regions B1a, the third electrode region B3 includes a plurality of third electrode regions B3a, the height of each first interdigital electrode B11 in each first electrode region B1a and the height of each third interdigital electrode B31 in each third electrode region B3a may be set to be between 0.98×h2 and H2 (may include 0.98×h2 and H2), and the height of each first reflective gate a11 in each first reflective gate region A1a and the height of each second reflective gate a21 in each second reflective gate region A2a may be between H2 and 1.04×h2 (may include H2 and 1.04×h2).

Or fig. 17 is a further cross-sectional view of fig. 6 along E3-E4, referring to fig. 6 and 17 in combination, when the first reflective gate region A1 includes a plurality of first reflective gate regions A1a, the second reflective gate region A2 includes a plurality of second reflective gate regions A2a, the first electrode region B1 includes a plurality of first electrode regions B1a, the third electrode region B3 includes a plurality of third electrode regions B3a, the height of each first interdigital electrode B11 in each first electrode region B1a and the height of each third interdigital electrode B31 in each third electrode region B3a may be set to be between H2 and 1.04×h2 (may include H2 and 1.04×h2), and the height of each first reflective gate a11 in each first reflective gate region A1a and the height of each second reflective gate a21 in each second reflective gate region A2a are set to be between 0.98×h2 and H2 (may include 0.98×h2 and H2).

Fig. 18 is a schematic diagram of Insertion Loss of a surface acoustic wave filter according to an embodiment of the present invention, and fig. 19 is a schematic diagram of partial amplification of fig. 18, in which fig. 18 is a graph showing a passband performance of a filter formed by the surface acoustic wave resonator shown in fig. 16 and a filter formed by a surface acoustic wave resonator in the prior art, fig. 9 is an intention of amplification in a frequency range of 1.92GHz to 2.02GHz in fig. 19, and an ordinate is an Insertion Loss IL (unit: dB) and an ordinate is a frequency f (unit: GHz). As shown in the figure, the insertion loss curve Lc5 of the surface acoustic wave filter of the present invention reduces the ripple intensity on the left side of the resonance point compared to the insertion loss curve Lc6 of the surface acoustic wave filter of the prior art, that is, the surface acoustic wave resonator of the present invention eliminates the parasitism on the left side of the resonance point (the resonance point of the series resonator is usually located in the middle of the passband), so that the insertion loss on the left side of the surface acoustic wave filter is improved by 0.7dB compared to the design of the prior art, and the passband of the filter becomes wider due to the overall improvement of the Q value of the resonator. Therefore, the surface acoustic wave filter designed according to the embodiment can improve the insertion loss and the squareness of the whole filter without changing the out-of-band rejection of the surface acoustic wave filter.

Based on the same inventive concept, the embodiment of the present invention further provides a surface acoustic wave filter, where the surface acoustic wave filter includes the surface acoustic wave resonator provided by any one embodiment of the present invention, so that the surface acoustic wave filter provided by the embodiment of the present invention includes the technical features of the surface acoustic wave resonator provided by any one embodiment of the present invention, and the beneficial effects of the surface acoustic wave resonator provided by any one embodiment of the present invention can be achieved, and the same points can be referred to the description of the surface acoustic wave resonator provided by any one embodiment of the present invention, and are not repeated herein.

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims (10)

1. A surface acoustic wave resonator, comprising: a piezoelectric layer and an electrode layer on the piezoelectric layer;

the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region;

the first reflective gate region, the first electrode region, the second electrode region, the third electrode region and the second reflective gate region are sequentially arranged along a first direction;

In the first reflective grating region, the electrode layer comprises first reflective gratings arranged in an array; the electrode layer comprises second reflecting grids arranged in an array in the second reflecting grid region; the electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; the electrode layer comprises second interdigital electrodes arranged in an array in the second electrode region; in the third electrode region, the electrode layer comprises third finger electrodes arranged in an array;

In a second direction, the first interdigital electrode has a first height H1, the second interdigital electrode has a second height H2, the third interdigital electrode has a third height H3, and the first reflective grating has a fourth height H4; the second reflective grating has a fifth height H5;

H1 is more than H2 and less than H4, and H3 is more than H2 and less than H5; or H4 < H2 < H1 and H5 < H2 < H3;

Wherein the first direction is perpendicular to the lamination direction of the piezoelectric layer and the electrode layer, and the second direction is parallel to the lamination direction of the piezoelectric layer and the electrode layer.

2. The surface acoustic wave resonator according to claim 1, characterized in that the fourth height H4 and the fifth height H5 satisfy: h4 =h5.

3. The surface acoustic wave resonator according to claim 1, characterized in that the first height H1 and the third height H3 satisfy: h1 =h3.

4. The surface acoustic wave resonator according to claim 1, characterized in that the first electrode zone comprises N1 first electrode zones; the third electrode region comprises N2 third electrode regions; n1 is more than or equal to 2, N2 is more than or equal to 2, and N1 and N2 are integers;

the heights of the first interdigital electrodes positioned in different first electrode subareas are different; and/or the heights of third finger electrodes located in different third electrode subregions are different.

5. The surface acoustic wave resonator according to claim 4, characterized in that n1=n2;

along the first direction, the lengths of the first electrode sub-regions are equal, the lengths of the third electrode sub-regions are equal, and the lengths of the first electrode sub-regions are equal to the lengths of the third electrode sub-regions.

6. The surface acoustic wave resonator according to claim 5, characterized in that the second electrode zone comprises a midline, the length of the second electrode zone being symmetrical about the midline along the first direction;

Along the first direction, the height of each first interdigital electrode in each first electrode subarea and the height of each third interdigital electrode in each third electrode subarea are symmetrical with respect to the central line of the second electrode area.

7. The surface acoustic wave resonator according to claim 1, characterized in that the first reflection gate region comprises N3 first reflection gate regions; the second reflective gate region comprises N4 second reflective gate regions; n3 is more than or equal to 2, N4 is more than or equal to 2, and N3 and N4 are integers;

The heights of the first reflecting grids positioned in different first reflecting grid subareas are different; and/or the heights of the second reflective gratings positioned in different second reflective grating sub-areas are different.

8. The surface acoustic wave resonator according to claim 7, characterized in that n3=n4;

Along the first direction, the lengths of the first reflective gate regions are equal, the lengths of the second reflective gate regions are equal, and the lengths of the first reflective gate regions are equal to the lengths of the second reflective gate regions.

9. The surface acoustic wave resonator according to claim 8, characterized in that the second electrode zone comprises a midline, the length of the second electrode zone being symmetrical about the midline along the first direction;

the height of each first reflecting grating in each first reflecting grating region and the height of each second reflecting grating in each second reflecting grating region are symmetrical with respect to the center line of the second electrode region along the first direction.

10. A surface acoustic wave resonator, comprising: a piezoelectric layer and an electrode layer on the piezoelectric layer;

the surface acoustic wave resonator further comprises a first reflecting gate region, a second reflecting gate region, a first electrode region, a second electrode region and a third electrode region;

the first reflective gate region, the first electrode region, the second electrode region, the third electrode region and the second reflective gate region are sequentially arranged along a first direction;

in the first reflective grating region, the electrode layer comprises first reflective gratings arranged in an array; the height of each first reflecting grating is increased or decreased along the first direction;

The electrode layer comprises second reflecting grids arranged in an array in the second reflecting grid region; the height of each second reflecting grating is increased or decreased along the first direction;

The electrode layer comprises first interdigital electrodes arranged in an array in the first electrode region; the height of each first interdigital electrode increases or decreases along the first direction;

The electrode layer comprises second interdigital electrodes arranged in an array in the second electrode region;

in the third electrode region, the electrode layer comprises third finger electrodes arranged in an array; the height of each third finger electrode is increased or decreased along the first direction;

The height of each first interdigital electrode is smaller than the height of each second interdigital electrode along the second direction, and the height of each second interdigital electrode is smaller than the height of each first reflecting grating; the height of each third interdigital electrode is smaller than that of each second interdigital electrode, and the height of each second interdigital electrode is smaller than that of each second reflecting grating;

or along the second direction, the height of each first reflecting grating is smaller than the height of each second interdigital electrode, and the height of each second interdigital electrode is smaller than the height of each first interdigital electrode; the height of each second reflecting grating is smaller than the height of each second interdigital electrode, and the height of each second interdigital electrode is smaller than the height of each third interdigital electrode;

Wherein the first direction is perpendicular to the lamination direction of the piezoelectric layer and the electrode layer, and the second direction is parallel to the lamination direction of the piezoelectric layer and the electrode layer.