CN221328934U - Speed change structure applied to surface acoustic wave resonator, resonator and filter - Google Patents

Abstract

The utility model discloses a speed change structure applied to a surface acoustic wave resonator, the resonator and a filter, and relates to the technical field of surface acoustic wave resonators. The variable speed structure is arranged at the tail end of the finger strip, the first structure body (i.e. the Piston structure) is combined with the second structure body positioned in the vertical projection area of the first structure body, the change of the discontinuity of the acoustic impedance in the plane direction and the vertical direction can be brought simultaneously, the adjusting range of the Piston structure can be enlarged, the heteromodal suppression effect of the resonator is improved, and the excitation and the propagation of the main acoustic mode are not influenced.

Description

Speed change structure applied to surface acoustic wave resonator, resonator and filter

Technical Field

The present utility model relates to the field of surface acoustic wave resonators, and in particular, to a speed change structure applied to a surface acoustic wave resonator, a resonator, and a filter.

Background

For any type of SAW resonator, the transversely propagating acoustic wave causes the resonator to have transverse resonant modes, namely clutter in and near the passband, which can increase device loss, cause the quality factor Q value to fluctuate greatly, and reduce the performance of the resonator and the filter.

Regarding how to suppress the lateral spurious mode in the saw resonator, the lateral spurious mode can be suppressed by using the Piston mode, but the Piston structure is limited by the semiconductor surface process, and there is a limit in the size and size thereof, and thus there is a limit in adjusting the effect of spurious mode reflection to cancel the lateral resonant mode.

Therefore, how to expand the adjustment range of the Piston structure, thereby improving the effect of the hybrid mode suppression of the resonator is a key problem to be solved by the technical scheme.

Disclosure of utility model

In order to solve at least one technical problem mentioned in the background art, the utility model aims to provide a speed change structure applied to a surface acoustic wave resonator, the resonator and a filter, and the adjustment range of a Piston mode can be enlarged.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

In a first aspect, an embodiment of the present utility model provides a speed change structure applied to a surface acoustic wave resonator, including

A first structure arranged at the tail end of the finger strip and at least two second structures which are positioned in the vertical projection area of the first structure and are spaced in a first direction, wherein the first direction is along the direction of the finger strip;

the first structure body has a height equal to the finger and a width greater than the finger.

Further, the second structure is disposed on a first surface or a second surface of the first structure, where the first surface is a side of the first structure away from the piezoelectric substrate, and the second surface is a side of the first structure close to the piezoelectric substrate.

Further, the plurality of second structures may have different widths in the first direction and/or different widths in the second direction, and the first direction and the second direction may be perpendicular to each other.

Further, the boundary of the second structure in the second direction is flush with the boundary of the first structure.

Further, the material of the second structure body includes Cu or Pt.

Further, the inner pitch of the adjacent second structures is 0.1 to 0.9 times the outer pitch.

In a second aspect, an embodiment of the present utility model provides a surface acoustic wave resonator, including

A piezoelectric substrate;

An interdigital structure layer positioned on one side surface of the piezoelectric substrate along a third direction; the interdigital structure layer comprises a first bus bar and a second bus bar which are oppositely arranged in a first direction, and finger bars which are arranged on the first bus bar and the second bus bar in a crossing way; the fingers on the first bus bar are arranged at intervals in a second direction, and the fingers on the second bus bar are arranged at intervals in the second direction; the first direction and the second direction are parallel to the surface of the piezoelectric substrate, and the first direction and the second direction are perpendicular to each other; the speed changing mechanism is characterized in that any one of the speed changing structures is arranged at the tail end of the finger strip.

Further, at least one second structure body of which the projection in the third direction does not exceed the boundary of the finger strip is arranged at a position of the finger strip close to the speed change structure;

And at least one second structure body with the projection in the third direction not exceeding the boundary of the finger strip is also arranged at the position of the finger strip corresponding to the second structure body of the adjacent finger strip.

Further, the method comprises the steps of,

The interdigital structure layer further comprises false fingers, the false fingers and the finger strips are alternately arranged on the first bus bar and the second bus bar, the finger strips on the first bus bar are in one-to-one correspondence with the false fingers on the second bus bar, the finger strips on the second bus bar are in one-to-one correspondence with the false fingers on the first bus bar, the corresponding finger strips and the false fingers are positioned on the same straight line, and gaps are reserved between the finger strips and the false fingers;

the first structure is also provided at the distal end of the prosthesis.

Further, at least one second structure, which projects in the third direction and does not exceed the boundary of the prosthesis, is also arranged at a position of the prosthesis, which is close to the first structure.

Further, also include

The reflection grids are positioned at two sides of the interdigital structure layer and are provided with a plurality of grid bars;

A speed change structure is also arranged on the grid bar at a position corresponding to the speed change structure;

And the second structure body with the projection in the third direction not exceeding the boundary of the grid is also arranged at the position corresponding to the second structure body on the grid.

Further, the finger strips are made of Cu or Al.

In a third aspect, an embodiment of the present utility model provides a filter, where the filter includes any one of the surface acoustic wave resonators described above.

Compared with the prior art, the utility model has the beneficial effects that:

The variable speed structure is arranged at the tail end of the finger strip, the first structure body (i.e. the Piston structure) is combined with the second structure body positioned in the vertical projection area of the first structure body, the change of the discontinuity of the acoustic impedance in the plane direction and the vertical direction can be brought simultaneously, the adjusting range of the Piston structure can be enlarged, the heteromodal suppression effect of the resonator is improved, and the excitation and the propagation of the main acoustic mode are not influenced.

Drawings

Fig. 1 is a top view of a square surface acoustic wave resonator with a first structure according to an embodiment of the present utility model;

Fig. 2 is a top view of a saw resonator with an elliptical first structure according to an embodiment of the present utility model;

Fig. 3 is a schematic diagram of a saw resonator after adjusting a width of a second structure according to an embodiment of the present utility model;

Fig. 4 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present utility model in a vertical section;

FIG. 5 is a schematic view of a cross-sectional line provided in an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a change in sound velocity perpendicular to the direction of propagation of sound waves according to an embodiment of the present utility model;

fig. 7 is a structural top view of a surface acoustic wave resonator with a false finger according to an embodiment of the present utility model;

FIG. 8 is a schematic diagram of a surface acoustic wave resonator with a false finger structure according to the present utility model with a sound velocity change perpendicular to the direction of propagation of the sound wave;

Fig. 9 is a top view of a surface acoustic wave resonator with a reflection grating according to an embodiment of the present utility model;

FIG. 10 is a schematic view of a surface acoustic wave resonator with reflective grating according to the present utility model with sound velocity change in a direction perpendicular to the propagation direction of sound waves;

FIG. 11 is a schematic view of a TC-SAW resonator in vertical cross section, in accordance with an embodiment of the present utility model;

Fig. 12 is a schematic structural diagram of a TF-SAW resonator according to an embodiment of the present utility model in a vertical cross section.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely, and it is apparent that the described embodiments are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The Surface Acoustic Wave (SAW) resonator and the filter are acoustic devices widely applied to the radio frequency field, integrate low insertion loss and good inhibition performance, have small volume, and mainly utilize the piezoelectric effect to mutually convert electric energy and mechanical energy for realizing gating characteristics for signal transmission in a combined way.

However, in any SAW resonator, the transverse resonant mode of the resonator, that is, noise in and near the passband, is caused by the transversely propagating acoustic wave, and this noise increases the loss of the device, so that the Q value of the quality factor fluctuates greatly, and the performance of the resonator and the filter is degraded. For how to suppress the lateral spurious modes in the saw resonator, the lateral spurious modes can be suppressed by using the Piston mode, but the Piston structure is limited by the semiconductor surface process, and there is a limit in the size and size, and there is a limit in adjusting the effect of spurious mode reflection to cancel the lateral resonant modes. Therefore, how to expand the adjustment range of the Piston structure, thereby improving the effect of the hybrid mode suppression of the resonator is a key problem to be solved by the technical scheme.

In order to solve the above-mentioned problems in the prior art, embodiments of the present utility model provide a speed change structure applied to a surface acoustic wave resonator, a resonator, and an electronic device, which are described in detail below.

In a first aspect, an embodiment of the present utility model provides a speed change structure applied to a surface acoustic wave resonator.

Embodiment one:

As shown in fig. 1, fig. 1 is a top view of a saw resonator with a square first structure according to an embodiment of the present utility model, and a variable speed structure 1024 in fig. 1 includes

A first structure 10241 provided at the tip of the finger bar and at least two second structures 10242 spaced apart in the first direction at the vertical projection area of the first structure 10241;

Wherein the first direction is along finger 1023;

The first structure 10241 has a height equal to the finger 1023 and a width greater than the finger 1023.

In fig. 1, the shift structure 1024 includes two parts.

The first part is a first structure 10241 with the height equal to the finger 1023 and the width larger than the finger 1023; the shape of the first structure may be square, oval, etc., and the width is larger than the finger 1023 and the height is equal to the finger 1023, which is not limited in the embodiment of the present utility model. For example, the first structure in fig. 1 is square, the first structure in fig. 2 is oval, and fig. 2 is a top view of a saw resonator with an oval first structure according to an embodiment of the present utility model;

the second portion is at least two second structures 10242 spaced apart in the first direction in a vertical projection area of the first structures 10241.

The material of the second structure is preferably a metal material having a relatively high density and relatively low resistivity, such as Pt or Cu, so that the acoustic velocity in the region is reduced by the mass loading effect of the metal without affecting the performance of the finger.

By varying the speed of sound, a Piston Mode effect is created such that the resonator creates distinct zones of differing speed of sound in the parallel finger direction, thereby suppressing spurious resonances in that direction.

Acoustic waves are typical elastic waves, when the elastic waves propagate in a substance, waves with propagation directions not parallel to the interface directions are reflected by interfaces (namely different acoustic velocity areas) of different media, so that the formation of resonance of a hybrid mode can be avoided, and energy dissipation is avoided. The removal of the transverse spurious modes is achieved by providing a second structure that reduces the speed of sound in this region and that reflects sound waves in directions other than the direction of propagation of the primary acoustic mode, dissipating its energy by reflection at the speed of sound interface.

The Piston structure is arranged at the tail end of the finger, so that the problems that the electric field at the tail end of the electrode finger is easily caused by the common finger structure, the sound velocity difference between the finger area and the gap area is overlarge and the like, which can cause the formation of transverse waveforms, are solved, but the Piston structure is limited by the surface technology of a semiconductor, and the size of the Piston structure are limited, so that the regulation limit exists on the effect of eliminating the resonator condition due to the reflection of a stray mode; the variable speed structure (i.e. the combination of the Piston structure and the second structure body which is positioned above the Piston structure and is not beyond the finger strip boundary in the vertical projection area) can simultaneously bring the change of the discontinuity of the acoustic impedance in the plane direction and the vertical direction, and can expand the adjustment range of the Piston structure, thereby improving the heteromodal suppression effect of the resonator and not influencing the excitation and propagation of the main acoustic mode.

Embodiment two:

On the basis of the first embodiment, the widths of the second structures in the first direction are different, and/or the widths in the second direction are different, the first direction and the second direction being perpendicular.

The "first direction" refers to a direction parallel to the finger, and the "second direction" refers to a direction perpendicular to the finger.

There is a limit to the adjustment range of the Piston structure, but the adjustment range of the Piston structure can be enlarged after the second structural body is added on the Piston structure. The width of the second structure body in the direction of the finger strip is inconsistent or the width of the second structure body in the direction perpendicular to the finger strip is inconsistent, so that the range of variation of capacitance of a variable speed structure area is different, more discontinuity is introduced, the range of acoustic impedance difference is different, and energy dissipation caused by a stray mode is better restrained.

Further, the widths of the second structures in the direction perpendicular to the finger strips are not uniform, and the widths of the second structures in the direction parallel to the finger strips are also not uniform, so that more discontinuities of capacitance changes can be introduced, and unevenly-changed acoustic impedance difference areas are formed, so that the sound velocity changes are different, and excitation of stray modes is further suppressed.

The variable speed structure applied to the surface acoustic wave resonator provided by the embodiment of the utility model can simultaneously bring the change of the discontinuity of the acoustic impedance in the plane direction and the vertical direction, and can expand the adjustment range of the Piston structure, thereby improving the heteromodal suppression effect of the resonator and not influencing the excitation and propagation of the main acoustic mode.

Embodiment III:

As shown in fig. 3, fig. 3 is a schematic diagram of a saw resonator with a second structure body with a width adjusted according to an embodiment of the present utility model, in fig. 3, a first structure body 30241 in a variable speed structure 304 is square, and a boundary of the second structure body 30242 in the second direction is flush with a boundary of the first structure body 30241.

The third embodiment can be similarly applied to the elliptical first structure in fig. 2, and the principle is similar, so this embodiment will be described by taking a square first structure as an example.

The second structure 30242 is adjusted in cooperation with the shape of the first structure 30241, so that the second structure 30242 can be just covered on the first structure 30241, more discontinuity of capacitance change can be introduced, and an unevenly-changed acoustic impedance difference region is formed, so that the sound velocity change is different, and excitation of a stray mode is further suppressed.

Embodiment four:

The difference from any of the first to third embodiments is that the second structural body is provided on the second surface of the first structural body, that is, on the side close to the piezoelectric substrate.

The same effect can be achieved by embedding the second structure below the first structure, i.e. in the surface recess of the piezoelectric substrate, which may bring about a change in the manufacturing process, but may bring about certain advantages for the subsequent processes, e.g. formation of a temperature compensation layer, passivation layer, etc.

Fifth embodiment:

in the foregoing embodiments, the inner pitch of the adjacent second structures is 0.1 to 0.9 times the outer pitch.

When the distance between the second structures is smaller than 0.1 times, compared with the wavelength, the second structures cannot generate obvious acoustic impedance change and reflection effect in a distance area;

Similarly, if the width of the second structure in the finger direction is more than 0.9 times, the second structure cannot have a significant acoustic impedance change and reflection effect in the second structure region because the width is too small compared to the wavelength.

In a second aspect, the embodiment of the utility model further provides a surface acoustic wave resonator.

Example six:

fig. 4 is a schematic structural view of a saw resonator according to an embodiment of the present utility model on a vertical cross section, including

A piezoelectric substrate 401;

an interdigital structural layer 402; the inter-digital structure layer includes a shift structure 4024.

Corresponding to the cross-sectional view of fig. 4, fig. 1 is a top view, and the specific structure of the interdigital structure layer 402 is described by taking fig. 1 as an example.

An interdigital structure layer 102 in fig. 1, which is located on one side surface of the piezoelectric substrate 101 along the third direction, includes a first bus bar 1021 and a second bus bar 1022 that are oppositely disposed in the first direction, and a finger 1023 that is located on the first bus bar 1021 and the second bus bar 1022 and is arranged in an intersecting manner; the fingers 1023 on the first bus bar 1021 are arranged at intervals in the second direction, and the fingers 1023 on the second bus bar 1022 are arranged at intervals in the second direction; the first direction and the second direction are parallel to the surface of the piezoelectric substrate 101, and the first direction and the second direction are perpendicular to each other.

The distal end of each finger 1023 is provided with a shift structure 1024 as in any one of the first to fifth embodiments described above.

It should be noted that, the cross-sectional structure shown in fig. 4 is a "schematic view", and since the structural features of the bus bar, the electrode finger bar, and the like need to be simultaneously represented in one drawing, fig. 4 is equivalent to a feature portion of two vertical cross-sectional views.

Fig. 5 is a schematic view of a cross-sectional line according to an embodiment of the present utility model, as shown in fig. 5. Fig. 5 includes two cross-sectional lines AA 'and BB', respectively, and cross-sectional views taken along the two cross-sectional lines combine to form the vertical cross-sectional schematic of fig. 4.

The piezoelectric substrate 401 may be made of quartz, aluminum nitride, LN (lithium niobate, liNbO 3), LT (lithium tantalate, liTaO 3), etc., and the present utility model is not limited thereto, and preferably a lithium niobate or lithium tantalate material, which has advantages of excellent piezoelectric effect and electromechanical coupling effect, etc., and is widely used in surface acoustic wave devices.

The interdigital structure layer 402, the interdigital structure layer 402 being deposited on the piezoelectric substrate 401, is the most basic unit constituting the surface acoustic wave resonator, and includes first and second bus bars 1021 and 1022 disposed opposite to each other at intervals in the first direction, and finger bars 1023 on the first and second bus bars 1021 and 1022.

The finger 1023 may be preferably made of a metal material such as Cu or Al.

As shown in fig. 6, fig. 6 is a schematic diagram of a sound velocity change perpendicular to a sound wave propagation direction according to an embodiment of the present utility model. In fig. 6, the sound velocity of the gap portion between the finger and the bus bar is highest, and the bus bar reduces the sound velocity; the second structure body is made of metal, so that the sound velocity can be reduced, and the sound velocity of the area where the second structure body is positioned is lower than that of the finger strip parts of which the two sides are not covered by the second structure body; the first structure (i.e., the white portion of the finger) has a sound velocity lower than that of the normal finger portion because it is wider than the normal finger structure; the speed of sound presents more discontinuities, further suppressing the energy dissipation by spurious modes.

The Piston structure is arranged at the tail end of the finger, so that the problems that the electric field at the tail end of the electrode finger is easily caused by the common finger structure, the sound velocity difference between the finger area and the gap area is overlarge and the like, which can cause the formation of transverse waveforms, are solved, but the Piston structure is limited by the surface technology of a semiconductor, and the size of the Piston structure are limited, so that the regulation limit exists on the effect of eliminating the resonator condition due to the reflection of a stray mode; the variable speed structure (i.e. the combination of the Piston structure and the second structure body which is positioned above the Piston structure and is not beyond the finger strip boundary in the vertical projection area) can simultaneously bring the change of the discontinuity of the acoustic impedance in the plane direction and the vertical direction, and can expand the adjustment range of the Piston structure, thereby improving the heteromodal suppression effect of the resonator and not influencing the excitation and propagation of the main acoustic mode.

Embodiment seven:

still referring to fig. 1, for example, at least one second structure 10242 having a projection in the third direction not exceeding the boundary of the finger 1023 is provided at a portion of each finger 1023 close to the speed change structure;

At least one second structure 10242 having a projection in the third direction not exceeding the boundary of the finger 1023 is also provided on the finger 1023 at a position corresponding to the second structure 10242 of the adjacent finger.

In this way, not only the second structure 10242 is included in the speed-changing structure, but also the second structure 10242 is arranged on the finger 1023, so that more discontinuous changes of acoustic impedance can be further introduced, the adjustment range of the Piston structure is enlarged, the effect of suppressing the hybrid mode of the resonator is improved, and the excitation and propagation of the main acoustic mode are not affected.

The "third direction" mentioned above refers to a direction perpendicular to a plane in which any surface of the piezoelectric substrate 201 is located.

Example eight:

Fig. 7 is a top view of a surface acoustic wave resonator with a dummy finger according to an embodiment of the present utility model.

On the basis of the sixth or seventh embodiment, the interdigital structure layer further includes dummy fingers 701, the dummy fingers 701 and the finger bars 702 are alternately arranged on the first bus bar 703 and the second bus bar 704, the finger bars 702 on the first bus bar 703 are in one-to-one correspondence with the dummy fingers 701 on the second bus bar 704, the finger bars 702 on the second bus bar 704 are in one-to-one correspondence with the dummy fingers 701 on the first bus bar 703, the corresponding finger bars 702 and the dummy fingers 701 are located on the same straight line, and a gap is provided between the finger bars 702 and the dummy fingers 701;

The first structural body 7011 is also provided at the distal end of the artificial finger 701, and the first structural body 7011 is also provided at a portion of the finger strip 702 corresponding to the distal end of the artificial finger 701.

The first structure body is arranged at the tail end of the false finger, so that the effect of better inhibiting the mixed mode can be realized, but the process requirement is higher as well, and the larger area is occupied; it should be noted that the scheme of optimizing the end structure of the double-sided finger strip using the artificial finger is not only applicable to the square first structure, but also applicable to other first structures, such as an ellipse.

As shown in fig. 8, fig. 8 is a schematic diagram of sound velocity change in a direction perpendicular to a sound wave propagation direction of a surface acoustic wave resonator with a false finger structure according to the present utility model.

In fig. 8, the sound velocity of the gap portion between the finger and the bus bar is highest, and the bus bar reduces the sound velocity; the second structure body is made of metal, so that the sound velocity can be reduced, and the sound velocity of the area where the second structure body is positioned is lower than that of the finger strip parts of which the two sides are not covered by the second structure body; the first structure (i.e., the white portion of the finger and the prosthetic finger) has a lower sound velocity than the normal finger portion because it is wider than the normal finger structure; the speed of sound presents more discontinuities, further suppressing the energy dissipation by spurious modes.

Similarly, at least one second structure body with projection in the third direction not exceeding the boundary of the false finger can be arranged on the false finger, more discontinuity of capacitance change can be introduced, and an unevenly-changed acoustic impedance difference area is formed, so that the sound velocity change is different, and excitation of a stray mode is further restrained.

Example nine:

The surface acoustic wave resonator according to any one of the sixth to eighth embodiments further includes a pair of reflection grids located on both sides of the interdigital structure layer, the reflection grids having a plurality of grid bars;

The grid bars are also provided with speed changing structures at positions corresponding to the speed changing structures in the interdigital structure layers;

the second structures on the grid corresponding to the second structures on the finger are also arranged on the positions of the grid, wherein the projection of the second structures in the third direction does not exceed the boundary of the grid.

Fig. 9 is a top view of a surface acoustic wave resonator with a reflection grating according to an embodiment of the present utility model.

Reflective grating 902 is disposed on both sides of the interdigital structure layer 901, the reflective grating 902 has a plurality of grating bars 9021, and the arrangement of the variable speed structure 9022 on the grating bars 9021 is the same as that of the variable speed structure 9012 on the finger bar 9011. The reflective grating 902 can reflect sound waves to help sound waves in the propagation direction of the main acoustic mode to form better resonance, so that the transmission performance of the resonator is improved, and the variable speed structure 9022 is arranged on the grating 9021 of the reflective grating 902, so that the energy dissipation of the stray mode can be further restrained.

The second structures 90221 that do not exceed the boundaries of the grating 9021 in the third direction are also provided on the grating 9021 of the reflection grating 902 at positions corresponding to the second structures 90121 on the finger 9011.

As shown in fig. 10, fig. 10 is a schematic diagram of a sound velocity change in a direction perpendicular to a sound wave propagation direction of a surface acoustic wave resonator with a reflection grating according to the present utility model.

In fig. 10, the sound velocity of the gap portion between the finger and the bus bar is highest, and the bus bar reduces the sound velocity; the second structure body is made of metal, so that the sound velocity can be reduced, and the sound velocity of the area where the second structure body is positioned is lower than that of the finger strip parts of which the two sides are not covered by the second structure body; the first structure (i.e., the white portion of the finger) has a sound velocity lower than that of the normal finger portion because it is wider than the normal finger structure; the speed of sound presents more discontinuities, further suppressing the energy dissipation by spurious modes.

Example ten:

The design of the variable speed structure of any of the above embodiments six through nine may also be used on TC-SAW resonators. FIG. 11 is a schematic view of a TC-SAW resonator in vertical cross section, including

A piezoelectric substrate 1101;

An interdigital structure layer 1102 located on one side surface of the piezoelectric substrate 1101 in the third direction, and including first and second bus bars 11021 and 11022 disposed opposite to each other in the first direction, and finger bars 11023 located on the first and second bus bars 11021 and 11022 and arranged alternately; the fingers 11023 on the first bus bar 11021 are arranged at intervals in the second direction, and the fingers 11023 on the second bus bar 11022 are arranged at intervals in the second direction; the first direction and the second direction are parallel to the surface of the piezoelectric substrate 1101, and the first direction and the second direction are perpendicular to each other; the end of each finger 11023 is provided with a first structural body 11024, and the part of each finger 11023 corresponding to the first structural body 11024 of the end of the adjacent finger is also provided with a first structural body 11024;

A temperature compensation layer 1103 that is located on one side of the piezoelectric substrate in the third direction and completely covers the interdigital structure layer 1102 in the third direction;

A second structure 1104, at least two second structures 1104 spaced apart in the first direction are disposed at the end of each finger 11023, the projection of the second structures 1104 in the third direction does not exceed the boundary of the finger 11023 (including the first structure 11024), the second structures 1104 are disposed on the first surface or the second surface of the finger 11023, the first surface is the side of the finger 11023 away from the piezoelectric substrate 1101, and the second surface is the side of the finger 11023 close to the piezoelectric substrate 1101;

At least two second structures 1104 spaced in the first direction are also provided on the finger 11023 at positions corresponding to the ends of the adjacent finger 11023, and the projection of the second structures 1104 in the third direction does not exceed the boundary of the finger 11023.

As in any of embodiments six through nine, the introduction of a first and second structure design TC-SAW resonator may introduce the avoidance of the formation of a hybrid mode resonance, and thus the avoidance of energy dissipation, as compared to conventional TC-SAW resonators. The Piston structure is combined with the second structure body which is positioned above the Piston structure and does not exceed the finger strip boundary in the vertical projection area, the change of the discontinuity of acoustic impedance in the plane direction and the vertical direction can be brought simultaneously, the adjusting range of the Piston structure can be enlarged, the heteromodal suppression effect of the resonator is improved, and the excitation and the propagation of the main acoustic mode are not influenced.

Example eleven:

The design of the variable speed structure of any of the above embodiments six through nine may also be used on TF-SAW resonators. FIG. 12 is a schematic view showing a structure of a TF-SAW resonator in a vertical section according to an embodiment of the utility model, including

A piezoelectric substrate 1201;

A piezoelectric thin film 1202 covering the piezoelectric substrate 1201;

An interdigital structure layer 1203, located on one side surface of the piezoelectric substrate 1201 along the third direction, comprising a first bus bar 12031 and a second bus bar 12032 oppositely disposed in the first direction, and finger bars 12033 located on the first bus bar 12031 and the second bus bar 12032 and arranged in an intersecting manner; the fingers 12033 on the first bus bar 12031 are arranged at intervals in the second direction, and the fingers 12033 on the second bus bar 12032 are arranged at intervals in the second direction; the first direction and the second direction are parallel to the surface of the piezoelectric substrate 1201, and are perpendicular to each other; the end of each finger 12033 is provided with a first structural body 12034, and the part of each finger 12033 corresponding to the first structural body 12034 of the end of the adjacent finger is also provided with a first structural body 12034;

A second structure 1204, at least two second structures 1204 spaced apart in the first direction are disposed at the end of each finger 12033, the projection of the second structure 1204 in the third direction does not exceed the boundary of the finger 12033, the second structure 1204 is disposed on the first surface or the second surface of the finger 12033, the first surface is the side of the finger 12033 away from the piezoelectric substrate 1201, and the second surface is the side of the finger 12033 near the piezoelectric substrate 1201;

at least two second structures 1204 spaced in the first direction are also disposed on the finger 12033 at positions corresponding to the ends of the adjacent finger 12033, and the projection of the second structures 1204 in the third direction does not exceed the boundary of the finger 12033 (including the first structures 12034).

As in any of embodiments six through nine, the TF-SAW resonator incorporating the variable speed structural design may incorporate the avoidance of the formation of a harmonic resonance by the hybrid mode, thereby avoiding energy dissipation, as compared to conventional TF-SAW resonators. The Piston structure is combined with the second structure body which is positioned above the Piston structure and does not exceed the finger strip boundary in the vertical projection area, the change of the discontinuity of acoustic impedance in the plane direction and the vertical direction can be brought simultaneously, the adjusting range of the Piston structure can be enlarged, the heteromodal suppression effect of the resonator is improved, and the excitation and the propagation of the main acoustic mode are not influenced.

Embodiment twelve:

in a third aspect, an embodiment of the present utility model further provides a filter, where the filter includes the surface acoustic wave resonator described in the foregoing embodiment.

The filter has the same effect as the surface acoustic wave resonator in the above embodiment.

In the description of the present application, it should be understood that, if any, these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., are used herein with respect to the orientation or positional relationship shown in the drawings, these terms refer to the orientation or positional relationship for convenience of description and simplicity of description only, and do not indicate or imply that the apparatus or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.

Furthermore, the terms "first," "second," and the like, if any, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "plurality" and "a plurality" if any, mean at least two, such as two, three, etc., unless specifically defined otherwise.

In the present application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly. For example, the two parts can be fixedly connected, detachably connected or integrated; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present application, unless expressly stated or limited otherwise, the meaning of a first feature being "on" or "off" a second feature, and the like, is that the first and second features are either in direct contact or in indirect contact through an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that if an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like, if any, are used herein for illustrative purposes only and are not meant to be the only embodiment.

It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present utility model may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (13)

1. A speed change structure applied to a surface acoustic wave resonator, characterized by comprising a first structure body arranged at a tip of a finger and at least two second structure bodies located in a vertical projection area of the first structure body and spaced in a first direction, wherein the first direction is a direction along the finger;

the first structure body has a height equal to the finger and a width greater than the finger.

2. The variable speed structure for a surface acoustic wave resonator according to claim 1, wherein the second structure is provided on a first surface or a second surface of the first structure, the first surface being a side of the first structure away from the piezoelectric substrate, and the second surface being a side of the first structure close to the piezoelectric substrate.

3. The speed change structure applied to a surface acoustic wave resonator according to claim 1, wherein the plurality of second structures are different in width in a first direction and/or different in width in a second direction, the first direction and the second direction being perpendicular to each other.

4. The speed change structure applied to a surface acoustic wave resonator according to claim 1, wherein a boundary of the second structure body in the second direction is flush with a boundary of the first structure body.

5. The variable speed structure for a surface acoustic wave resonator according to claim 1, wherein the material of the second structure body comprises Cu or Pt.

6. The variable speed structure for surface acoustic wave resonator according to claim 1, wherein the inner pitch of the adjacent second structures is 0.1 to 0.9 times the outer pitch.

7. A surface acoustic wave resonator includes

A piezoelectric substrate;

An interdigital structure layer positioned on one side surface of the piezoelectric substrate along a third direction; the interdigital structure layer comprises a first bus bar and a second bus bar which are oppositely arranged in a first direction, and finger bars which are arranged on the first bus bar and the second bus bar in a crossing way; the fingers on the first bus bar are arranged at intervals in a second direction, and the fingers on the second bus bar are arranged at intervals in the second direction; the first direction and the second direction are parallel to the surface of the piezoelectric substrate, and the first direction and the second direction are perpendicular to each other; characterized in that the ends of the finger strips are provided with the gear change structure of claim 1.

8. The surface acoustic wave resonator according to claim 7, characterized in that at least one second structure body whose projection in the third direction does not exceed the boundary of the finger is provided at a position where the finger approaches the speed change structure;

And at least one second structure body with the projection in the third direction not exceeding the boundary of the finger strip is also arranged at the position of the finger strip corresponding to the second structure body of the adjacent finger strip.

9. The saw resonator of claim 7, wherein the interdigital structure layer further comprises dummy fingers, the dummy fingers and the finger strips are alternately arranged on the first bus bar and the second bus bar, the finger strips on the first bus bar are in one-to-one correspondence with the dummy fingers on the second bus bar, the finger strips on the second bus bar are in one-to-one correspondence with the dummy fingers on the first bus bar, the corresponding finger strips and the dummy fingers are on the same line, and a gap is provided between the finger strips and the dummy fingers;

the first structure is also provided at the distal end of the prosthesis.

10. The surface acoustic wave resonator according to claim 9, characterized in that at least one second structure whose projection in the third direction does not exceed the boundary of the artificial finger is also provided at a position where the artificial finger approaches the first structure.

11. The surface acoustic wave resonator according to any of claims 7-10, characterized by further comprising

The reflection grids are positioned at two sides of the interdigital structure layer and are provided with a plurality of grid bars;

A speed change structure is also arranged on the grid bar at a position corresponding to the speed change structure;

And the second structure body with the projection in the third direction not exceeding the boundary of the grid is also arranged at the position corresponding to the second structure body on the grid.

12. The surface acoustic wave resonator according to claim 7, characterized in that the finger is made of Cu or Al.

13. A filter comprising the surface acoustic wave resonator of any one of claims 7 to 12.