Filter and radio frequency front-end module

Abstract

The utility model relates to the technical field of integrated circuits, in particular to a filter and a radio frequency front-end module, the filter comprises a plurality of resonance units, the resonance units are divided into series resonance units connected in series on a connection path between a first terminal and a second terminal and parallel resonance units, one end of each parallel resonance unit is connected to the connection path, and the other end of each parallel resonance unit is grounded; each resonance unit comprises at least one interdigital transduction structure, each interdigital transduction structure comprises a plurality of first electrode fingers and a plurality of second electrode fingers, an area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area comprises a middle area and an edge area; the resonance unit further comprises suppression parts which are arranged corresponding to the edge areas; the length of the resonance area of the parallel resonance unit in the second direction is greater than that of the resonance area of the series resonance unit in the second direction; the length of the suppression part of the parallel resonance unit is greater than the length of the suppression part of the series resonance unit. According to the invention, the effect of eliminating various stray modes can be achieved.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and in particular to filters and radio frequency front-end modules. Background Art

[0002] In addition to the main mode, filters also contain a variety of spurious modes. Some of these spurious modes fall within the filter passband, creating notches within the passband and significantly affecting filter performance.

[0003] However, existing filters can only suppress a single spurious mode and are unable to simultaneously overcome the adverse effects of multiple spurious modes and the mutual coupling between them. Utility Model Content

[0004] In view of the above problems, the embodiments of the present application provide a filter and a radio frequency front-end module to solve the above technical problems.

[0005] An embodiment of the present application provides a filter, comprising a plurality of resonant units, wherein the resonant units are divided into a series resonant unit connected in series to a connection path between a first terminal and a second terminal, and a parallel resonant unit having one end connected to the connection path and the other end grounded;

[0006] Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction, wherein the first direction is a propagation direction of sound waves;

[0007] An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction;

[0008] The resonance unit further includes a suppression portion arranged corresponding to each of the edge regions;

[0009] Wherein, the length of the resonance region of the parallel resonance unit in the second direction is greater than the length of the resonance region of the series resonance unit in the second direction;

[0010] The length of the suppression portion of the parallel resonance unit is greater than the length of the suppression portion of the series resonance unit.

[0011] Optionally, a length of the suppression portion of the parallel resonance unit in the first direction is greater than a length of the suppression portion of the series resonance unit in the first direction.

[0012] Optionally, a length of the suppression portion of the parallel resonance unit in the third direction is greater than a length of the suppression portion of the series resonance unit in the third direction, wherein the third direction is perpendicular to the first direction and the second direction.

[0013] Optionally, the length of the suppression portion of the series resonance unit is 0.05λ-0.1λ smaller than the length of the suppression portion of the parallel resonance unit, where λ is the wavelength of the sound wave.

[0014] Optionally, the resonance region includes a first edge region, a middle region and a second edge region arranged in sequence along the second direction, and the suppression portion includes a first suppression portion and a second suppression portion, the first suppression portion corresponds to the first edge region, and the first suppression portion is arranged on the first electrode finger and / or the second electrode finger; the second suppression portion corresponds to the second edge region, and the second suppression portion is arranged on the first electrode finger and / or the second electrode finger.

[0015] Optionally, the inhibition portion is arranged on at least a portion of the first electrode finger, and the inhibition portion is located at least at the end of the first electrode finger facing away from the first bus bar. The inhibition portion is arranged on at least a portion of the second electrode finger, and the inhibition portion is located at least at the end of the second electrode finger facing away from the second bus bar.

[0016] Optionally, the suppression portion is protruded from the edge area in the third direction, and the third direction is perpendicular to the first direction and the second direction.

[0017] Optionally, the suppression portion is protruding from the edge area in the first direction.

[0018] Optionally, the suppression portion covers the edge area in the third direction, and the third direction is perpendicular to the first direction and the second direction.

[0019] Optionally, a length of the resonance region of the parallel resonance unit in the second direction is 20λ-40λ, wherein λ is the wavelength of the sound wave.

[0020] Optionally, a length of the resonance region of the series resonance unit in the second direction is 10λ-20λ, wherein λ is the wavelength of the sound wave.

[0021] Optionally, the duty cycle of the parallel resonance unit is greater than the duty cycle of the series resonance unit.

[0022] Optionally, the duty cycle of the parallel resonance unit is 0.03-0.08 greater than the duty cycle of the series resonance unit.

[0023] Optionally, the duty cycle of the parallel resonance unit is 0.45-0.65, and the duty cycle of the series resonance unit is 0.4-0.6.

[0024] Optionally, the resonance frequency of the parallel resonance unit is outside the passband of the filter, and the resonance frequency of the series resonance unit is within the passband.

[0025] Optionally, it further includes a high acoustic velocity layer, wherein the high acoustic velocity layer covers the interdigital transducer structure, and the thickness of the high acoustic velocity layer in the third direction is 40-70 nm.

[0026] The filter provided in the embodiment of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes. Taking a filter whose main mode is a Rayleigh mode and whose spurious modes are SH (Shear Horizontal) mode and transverse mode as an example, the length of the resonance region of the parallel resonance unit in the second direction is greater than the length of the resonance region of the series resonance unit in the second direction, which can achieve the effect of suppressing the SH mode and high-order transverse mode, and the length of the suppression portion of the parallel resonance unit is greater than the length of the suppression portion of the series resonance unit, which can achieve the effect of suppressing the transverse mode. The two effects are superimposed, which can suppress the SH mode and transverse mode as much as possible, thereby avoiding the mutual coupling of the SH mode and the transverse mode, thereby further eliminating the SH mode and the transverse mode at the same time.

[0027] An embodiment of the present application further provides a filter, comprising a plurality of resonant units, wherein the resonant units are divided into a series resonant unit connected in series to a connection path between a first terminal and a second terminal, and a parallel resonant unit having one end connected to the connection path and the other end grounded;

[0028] Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, and the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction;

[0029] An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction;

[0030] The duty cycle of the parallel resonance unit is greater than that of the series resonance unit, and the length of the resonance region of the parallel resonance unit in the second direction is greater than the length of the resonance region of the series resonance unit in the second direction.

[0031] The filter provided in the embodiment of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes. Taking a filter whose main mode is a Rayleigh mode and whose spurious modes are an SH mode and a transverse mode as an example, the duty cycle of the parallel resonant unit is greater than the duty cycle of the series resonant unit, which can achieve the effect of suppressing the SH mode, and the length of the resonant region of the parallel resonant unit in the second direction is greater than the length of the resonant region of the series resonant unit in the second direction, which can achieve the effect of suppressing the SH mode and high-order transverse modes. The superposition of the two effects can not only better suppress the SH mode, but also suppress the transverse mode as much as possible, weaken the mutual coupling between the SH mode and the transverse mode, and further eliminate the SH mode and the transverse mode at the same time.

[0032] An embodiment of the present application further provides a filter, comprising a plurality of resonant units, wherein the resonant units are divided into a series resonant unit connected in series to a connection path between a first terminal and a second terminal, and a parallel resonant unit having one end connected to the connection path and the other end grounded;

[0033] Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, and the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction;

[0034] An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction;

[0035] The resonance unit further includes a suppression portion arranged corresponding to each of the edge regions;

[0036] The length of the suppression portion of the parallel resonance unit is greater than the length of the suppression portion of the series resonance unit, and the duty cycle of the parallel resonance unit is greater than the duty cycle of the series resonance unit.

[0037] The filter provided in the embodiments of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes. Taking a filter whose main mode is a Rayleigh mode and whose spurious modes are an SH mode and a transverse mode as an example, the length of the suppression portion of the parallel resonant unit is greater than the length of the suppression portion of the series resonant unit, which can achieve the effect of suppressing the transverse mode, and the duty cycle of the parallel resonant unit is greater than the duty cycle of the series resonant unit, which can achieve the effect of suppressing the SH mode. The superposition of these two effects can better suppress the SH mode and the transverse mode, thereby avoiding the mutual coupling of the SH mode and the transverse mode, thereby further eliminating the SH mode and the transverse mode at the same time.

[0038] An embodiment of the present application also provides a radio frequency front-end module, comprising the filter provided by any of the above embodiments.

[0039] These and other aspects of the present application will become more readily apparent from the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure shows a structural block diagram of the filter provided in an embodiment of the present application.

[0041] Figure 2 A schematic structural diagram of the interdigital transducer structure provided in an embodiment of the present application is shown.

[0042] Figure 3 A schematic structural diagram of the interdigital transducer structure provided in an embodiment of the present application is shown.

[0043] Figure 4 A schematic structural diagram of the interdigital transducer structure provided in an embodiment of the present application is shown.

[0044] Figure 5 Shown Figure 4 A structural schematic diagram of the AA section;

[0045] Figure 6 Shown Figure 4 Another structural schematic diagram of the AA section view;

[0046] Figure 7 A schematic structural diagram of a filter provided in an embodiment of the present application is shown.

[0047] Figure 8 A schematic structural diagram of a filter provided in an embodiment of the present application is shown.

[0048] Figure 9 A schematic structural diagram of the interdigital transducer structure provided in an embodiment of the present application is shown.

[0049] Figure 10 A schematic structural diagram of the interdigital transducer structure provided in an embodiment of the present application is shown.

[0050] Figure 11 FIG. 4 shows a graph of the admittance parameter of a resonator in the related art.

[0051] Figure 12 Shown by Figure 11 Comparison chart of the scattering parameter curve of the filter composed of resonators and the admittance parameter curve of some resonators in the filter.

[0052] Figure 13 A comparison of the admittance parameter curves of three resonators with different suppression portion lengths is shown.

[0053] Figure 14 A comparison of the admittance parameter curves of two resonators with different duty cycles is shown.

[0054] Figure 15 A comparison of the admittance parameter curves of three resonators with different resonance region lengths is shown.

[0055] Figure 16 A comparison of the scattering parameter curves of two filters with different high-acoustic-velocity layer thicknesses is shown. DETAILED DESCRIPTION

[0056] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0057] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0058] In the embodiments of the present application, it should be noted that, in this document, relational terms such as first and second, etc., are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0059] Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0060] In the description of the embodiments of this application, words such as "example" or "for example" are used to indicate an example, illustration, or description. Any embodiment or design described as "for example" or "for example" in the embodiments of this application is not to be construed as being preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to clearly present relative concepts.

[0061] In addition, in the embodiments of the present application, "plurality" refers to two or more. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two, or more. For example, "including at least one" means including one, two, or more, and does not limit which ones are included. For example, "including at least one of A, B, and C" means including A, B, C, A and B, A and C, B and C, or A, B, and C.

[0062] It should be noted that in the embodiments of the present application, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects are in an "or" relationship.

[0063] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0064] (Example 1)

[0065] An embodiment of the present application provides a filter 10, please refer to Figure 1 , including multiple resonant units 1. The resonant units 1 are divided into series resonant units 1a and parallel resonant units 1b. The series resonant unit 1a is connected in series to the connection path between the first terminal 20 and the second terminal 30. One end of the parallel resonant unit 1b is connected to the connection path, and the other end of the parallel resonant unit 1b is grounded.

[0066] Each resonant unit 1 includes at least one interdigital transducer structure 101, and the interdigital transducer structure 101 includes a first bus bar 1011, a second bus bar 1012, a first electrode finger 1013, and a second electrode finger 1014. Figure 2 The first bus bar 1011 is arranged opposite to the second bus bar 1012. There are multiple first electrode fingers 1013 and multiple second electrode fingers 1014, all of which are connected to the first bus bar 1011, and each of which extends toward the second bus bar 1012. All of the second electrode fingers 1014 are connected to the second bus bar 1012, and each of which extends toward the first bus bar 1011. All of the first electrode fingers 1013 and all of the second electrode fingers 1014 are alternately arranged in sequence along a first direction, wherein the first direction is the propagation direction of the acoustic waves excited by the multiple first electrode fingers 1013 and the multiple second electrode fingers 1014.

[0067] Please refer to Figure 2 The region where the first electrode finger 1013 and the second electrode finger 1014 intersect is a resonance region 1015 . The resonance region 1015 includes a middle region 10151 and an edge region 10152 arranged along a second direction, wherein the second direction is perpendicular to the first direction.

[0068] Please refer to Figure 3 、 Figure 4 、 Figure 9 and Figure 10 The resonant unit 1 further includes a suppressing portion 102 provided corresponding to each edge region 10152. The suppressing portion can adjust the sound velocity of the edge region 10152 so that the edge region 10152 forms a potential barrier, thereby eliminating the adverse effects of the transverse mode, effectively preventing energy leakage, and thus improving the quality factor of the filter.

[0069] The length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction is greater than the length W of the resonance region 1015 of the series resonance unit 1a in the second direction. It can be understood that the length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction is the aperture size of the parallel resonance unit 1b; and the length W of the resonance region 1015 of the series resonance unit 1a in the second direction is the aperture size of the series resonance unit 1a. The aperture of the parallel resonance unit 1b is greater than the aperture of the series resonance unit 1a.

[0070] The length of the suppression portion 102 of the parallel resonant unit 1 b is greater than the length of the suppression portion 102 of the series resonant unit 1 a .

[0071] As an example, the suppression part 102 can be a piston or a hammer.

[0072] In this embodiment, each series resonance unit 1a includes at least one resonator, and each parallel resonance unit 1b includes at least one resonator.

[0073] The filter 10 provided in the embodiment of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes.

[0074] The following description uses a resonator whose main mode is the Rayleigh mode and whose spurious modes are mainly the SH mode and the transverse mode as an example.

[0075] In the related art, for example, in a resonator using a lithium niobate substrate as the piezoelectric substrate 2 and having a cut angle in the range of 110°-130° in the YX direction, the main mode is the Rayleigh mode. Figure 11 The admittance curve shown in FIG, wherein curve S11 is the admittance curve and curve S12 is the real part of the admittance curve. Figure 11 The resonator's spurious modes, namely the SH (Shear Horizontal) mode and the transverse mode, are clearly visible in the local B. Failure to suppress these spurious modes will form pits within the passband, affecting the filter's flatness and leading to leakage of the main mode energy, a reduction in the quality factor, and, consequently, the overall insertion loss of the filter.

[0076] See also Figure 12 The scattering parameter curve of the filter composed of the above resonators and the admittance parameter curve comparison diagram of some resonators in the filter are shown. The structure of the filter is a trapezoidal structure, wherein curve S21 is the real part of the admittance curve of one of the series resonators, curves S22 and S23 are the real part of the admittance curves of two parallel resonators, respectively, and curve S24 is the scattering parameter curve of the filter. Figure 12 The ordinate on the left corresponds to the real part of the admittance curve, Figure 12 The vertical axis on the right corresponds to the scattering parameter curve. The SH mode usually appears at a frequency of about 60-80MHz to the right of the resonator's resonance point, and the SH mode that affects the passband mainly exists in the parallel resonator, see Figure 12 Similarly, since the transverse mode mainly exists above the resonance point, the effect of the transverse mode on the filter passband also mainly exists in the parallel resonator. Some transverse modes of the series resonator located in the middle of the passband frequency will also affect the passband, resulting in a large pit in the passband.

[0077] Also, please refer to Figure 13The admittance curve comparison diagram shown in FIG3 shows that curve S31, curve S32, and curve S33 are respectively the real part of the admittance curves of the three resonators. The three resonators differ only in the length of the suppression part, and the other parameters are the same. The length of the suppression part of the resonator corresponding to curve S31 is greater than the length of the suppression part of the resonator corresponding to curve S32, and the length of the suppression part of the resonator corresponding to curve S32 is greater than the length of the suppression part of the resonator corresponding to curve S33. Figure 13 As can be seen from the local D, the suppression section 102 can effectively suppress the transverse mode within a certain range. However, completely suppressing the transverse mode usually results in the appearance of BO modes (border modes) in the resonator, that is, the resonant point of the resonator is split, which also causes a pit in the filter passband.

[0078] In the embodiment of the present application, the resonant frequency of the parallel resonant unit 1b is outside the passband of the filter 10, and the transverse mode of the parallel resonant unit 1b will have a greater impact on the passband. Even if the BO mode appears, it will not have a significant impact on the passband. The resonant frequency of the series resonant unit 1a is within the passband, and the appearance of the BO mode will affect the passband flatness. Therefore, in the embodiment of the present application, in comparison, the parallel resonant unit 1b has a longer suppression portion 102, so that the transverse mode is completely suppressed, while the series resonant unit 1a has a shorter suppression portion 102, thereby controlling the resonant frequency of the series resonant unit 1a within a range where the BO mode does not appear.

[0079] Also, please refer to Figure 14 The admittance curve comparison diagram shown in FIG4 shows that curve S41 and curve S42 are the real part curves of the admittance of two resonators with different duty cycles, wherein the duty cycle of the resonator corresponding to curve S41 is greater than the duty cycle of the resonator corresponding to curve S42. Figure 14 As can be seen from the local E of the resonator, adjusting the duty cycle of the electrode fingers can suppress the SH mode, but it is difficult to completely eliminate the SH mode. Similarly, in a ladder-structured filter, the SH mode of the parallel resonator mainly falls within the passband, and the SH mode couples with the nearby transverse modes, resulting in a large pit in the passband. It is difficult to completely suppress both spurious modes by simply adjusting the duty cycle.

[0080] In the embodiment of the present application, the length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction is greater than the length W of the resonance region 1015 of the series resonance unit 1a in the second direction, which can not only suppress the SH mode and the high-order transverse mode, but also reduce the coupling between the transverse mode and the SH mode. Figure 15The admittance curve comparison diagram shown in FIG5 shows that the length W of the resonant region 1015 of the resonator in the second direction corresponding to curve S51 is 15λ, the length W of the resonant region 1015 in the second direction corresponding to curve S52 is 20λ, and the length W of the resonant region 1015 in the second direction corresponding to curve S53 is 30λ. λ is the wavelength of the acoustic wave excited by the plurality of first electrode fingers 1013 and the plurality of second electrode fingers 1014. Figure 15 It can be seen from the local F that as the length W of the resonance region 1015 in the second direction increases, the high-order transverse mode is significantly weakened, and the direct coupling of the heterogeneous mode is also suppressed to a certain extent.

[0081] In the embodiment of the present application, the length of the suppression portion 102 of the parallel resonant unit 1b is greater than the length of the suppression portion 102 of the series resonant unit 1a, which can achieve the effect of suppressing the transverse mode. In addition, the length W of the resonance region 1015 of the parallel resonant unit 1b in the second direction is greater than the length W of the resonance region 1015 in the second direction of the series resonant unit 1a, which can achieve the effect of suppressing the SH mode and high-order transverse modes. The combination of these two effects can weaken the mutual coupling between the SH mode and the transverse mode, thereby further eliminating the SH mode and the transverse mode.

[0082] In some embodiments, see Figure 2 As shown, the resonance region 1015 includes a first edge region 10152a, a middle region 10151, and a second edge region 10152b. The first edge region 10152a, the middle region 10151, and the second edge region 10152b are arranged sequentially along the second direction. The suppression portion 102 includes a first suppression portion 102a and a second suppression portion 102b. The first suppression portion 102a corresponds to the first edge region 10152a and is provided on at least one of the first electrode fingers 1013 and the second electrode fingers 1014. The second suppression portion 102b corresponds to the second edge region 10152b and is provided on at least one of the first electrode fingers 1013 and the second electrode fingers 1014.

[0083] In this embodiment, a first suppression portion 102a is provided in the first edge region 10152a on one side of the middle region 10151, and a second suppression portion 102b is provided in the second edge region 10152b on the other side of the middle region 10151, so that the sound velocity of the first edge region 10152a and the second edge region 10152b is lower than the sound velocity of the middle region 10151, thereby optimizing the sound wave propagation path and energy distribution, reducing edge effects, improving filtering performance, and improving the transverse mode suppression effect.

[0084] As an example, please refer to Figure 3 and Figure 9 The first electrode finger 1013 and the second electrode finger 1014 are both provided with a first suppression portion 102a, and the first electrode finger 1013 and the second electrode finger 1014 are both provided with a second suppression portion 102b, thereby further making the sound velocity of the first edge area 10152a and the second edge area 10152b lower than the sound velocity of the middle area 10151, further optimizing the sound wave propagation path and energy distribution, further reducing the edge effect, further improving the filtering performance and improving the transverse mode suppression effect.

[0085] As an example, please refer to Figure 4 and Figure 10 A first suppression portion 102a is provided on the first electrode finger 1013, and a second suppression portion 102b is provided on the second electrode finger 1014. This not only has a simple structure and is easy to prepare, but also can effectively optimize the sound wave propagation path and energy distribution, reduce edge effects, improve filtering performance, and improve the transverse mode suppression effect.

[0086] It should be noted that in other embodiments, the second suppressing portion 102b may be provided only on the first electrode fingers 1013, or the first suppressing portion 102a may be provided only on the second electrode fingers 1014. Alternatively, the first suppressing portion 102a may be provided on both the first electrode fingers 1013 and the second electrode fingers 1014. The filter 10 includes only the first suppressing portion 102a or the second suppressing portion 102b, which will not be described in detail here.

[0087] In some embodiments, see Figure 3 、 Figure 4 、 Figure 9 and Figure 10 The suppressing portion 102 is provided on at least a portion of the first electrode finger 1013, and is located at least at the end of the first electrode finger 1013 facing away from the first bus bar 1011. The suppressing portion 102 is provided on at least a portion of the second electrode finger 1014, and is located at least at the end of the second electrode finger 1014 facing away from the second bus bar 1012.

[0088] In this embodiment, the suppressing portion 102 is provided at least at the end of the first electrode finger 1013 facing away from the first bus bar 1011 and at the end of the second electrode finger 1014 facing away from the second bus bar 1012. The ends of the electrode fingers facing away from the bus bar are further away from the excitation point of the acoustic wave than the ends of the electrode fingers connected to the bus bar. Compared to placing the suppressing portion 102 at the ends of the first electrode finger 1013 connected to the first bus bar 1011 and the ends of the second electrode finger 1014 connected to the second bus bar 1012, this embodiment can more effectively reflect or scatter the acoustic wave, thereby optimizing the propagation path and energy distribution of the acoustic wave. Furthermore, placing the suppressing portion 102 at the ends of the first electrode finger 1013 facing away from the first bus bar 1011 and the ends of the second electrode finger 1014 facing away from the second bus bar 1012 enhances the mechanical stability and reliability of these ends, making the first and second electrode fingers 1013 and 1014 more resistant to external shock and vibration.

[0089] In some embodiments, see Figures 3 to 5 The suppression portion 102 can be protruded from the edge region 10152 in a third direction perpendicular to the first and second directions. The suppression portion 102 protruding from the edge region 10152 can lower the sound velocity in the edge region 10152 than in the middle region 10151, thereby optimizing the sound wave propagation path and energy distribution, reducing edge effects, improving filtering performance, and enhancing transverse mode suppression.

[0090] Correspondingly, when the suppression portion 102 is protruding from the edge area 10152 in the third direction, the length L1 of the suppression portion 102 of the parallel resonant unit 1b in the third direction is greater than the length L1 of the suppression portion 102 of the series resonant unit 1a in the third direction, thereby achieving the effect of effectively suppressing the transverse mode.

[0091] It can be understood that the suppression portion 102 is provided protruding from the edge region 10152 in the third direction, that is, a thickened structure is provided on the finger strips in the edge region 10152 to form the suppression portion 102. The thickness of the thickened structure provided on the finger strips in the edge region 10152 of the parallel resonant unit 1b is greater than the thickness of the thickened structure provided on the finger strips in the edge region 10152 of the series resonant unit 1a.

[0092] As an example, when the inhibiting portion 102 is protruding from the edge region 10152 in the third direction, the inhibiting portion 102 is made of metal. For example, the inhibiting portion 102 can be integrally formed with the corresponding electrode finger, which is more convenient to manufacture, effectively reduces process costs, and improves manufacturing efficiency.

[0093] In some embodiments, see Figure 9 and Figure 10The suppression portion 102 may be provided protrudingly in the first direction from the edge region 10152. The suppression portion 102 provided protrudingly in the edge region 10152 may make the sound velocity in the edge region 10152 lower than the sound velocity in the middle region 10151, thereby optimizing the sound wave propagation path and energy distribution, reducing edge effects, improving filtering performance, and enhancing transverse mode suppression.

[0094] It can be understood that the suppression portion 102 is provided protruding from the edge region 10152 in the first direction, that is, the widening structure is provided on the fingers of the edge region 10152 to form the suppression portion 102. The width of the widening structure provided on the fingers of the edge region 10152 of the parallel resonant unit 1b is greater than the width of the widening structure provided on the fingers of the edge region 10152 of the series resonant unit 1a.

[0095] Correspondingly, when the suppression portion 102 is protruding from the edge area 10152 in the first direction, the length L2 of the suppression portion 102 of the parallel resonant unit 1b in the first direction is greater than the length L2 of the suppression portion 102 of the series resonant unit 1a in the first direction, thereby achieving the effect of effectively suppressing the transverse mode.

[0096] As an example, when the inhibiting portion 102 is protruding from the edge region 10152 in the first direction, the inhibiting portion 102 is made of metal. For example, the inhibiting portion 102 can be integrally formed with the corresponding electrode finger, which is more convenient to manufacture, effectively reduces process costs, and improves manufacturing efficiency.

[0097] In some embodiments, see Figure 6 and Figure 7 The suppression portion 102 covers the edge area 10152 in the third direction, which can make the sound speed in the edge area 10152 lower than the sound speed in the middle area 10151, thereby optimizing the sound wave propagation path and energy distribution, reducing edge effects, improving filtering performance and improving transverse mode suppression effects.

[0098] It is understood that the filter 10 may further include a piezoelectric substrate 2, with the piezoelectric substrate 2, the interdigital transducer structure 101, and the suppressing portion 102 being sequentially arranged along a third direction. The suppressing portion 102 covers the edge region 10152 in the third direction, i.e., the suppressing portion 102 is provided on the fingers of the edge region 10152 and is made of a different material than the fingers. It is understood that the suppressing portion 102 may directly contact the edge region 10152. Alternatively, the suppressing portion 102 may not directly contact the edge region 10152, and other structures may be provided between the suppressing portion 102 and the edge region 10152.

[0099] Accordingly, when the suppression portion 102 covers the edge area 10152 in the third direction, the length L3 of the suppression portion 102 of the parallel resonant unit 1b in the third direction is greater than the length L3 of the suppression portion 102 of the series resonant unit 1a in the third direction, thereby achieving the effect of effectively suppressing the transverse mode.

[0100] As an example, when the inhibiting portion 102 covers the edge region 10152 in the third direction, the material of the inhibiting portion 102 may include silicon nitride.

[0101] Specifically, please refer to Figure 7 The filter 10 may further include a piezoelectric substrate 2 and a temperature compensation layer 3. The interdigital transduction structure 101 is disposed on the piezoelectric substrate 2. The temperature compensation layer 3 is divided into a first portion 301 and a second portion 302. The first portion 301 covers the interdigital transduction structure 101. The suppression portion 102 is disposed on the first portion 301. The second portion 302 covers the suppression portion 102 and the first portion 301, thereby effectively protecting the suppression portion 102 and the interdigital transduction structure 101.

[0102] In some embodiments, the length of the suppression portion 102 of the series resonant unit 1a is 0.05λ-0.1λ less than the length of the suppression portion 102 of the parallel resonant unit 1b. As an example, the length of the suppression portion 102 of the series resonant unit 1a may be 0.06λ, 0.07λ, 0.08λ, etc. less than the length of the suppression portion 102 of the parallel resonant unit 1b.

[0103] In this embodiment, not only can the transverse mode be effectively and completely suppressed, but the series resonant unit 1a also has a shorter suppression portion 102, so that the resonant frequency of the series resonant unit 1a can be controlled within a range where the BO mode does not occur.

[0104] In some embodiments, the length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction is 20λ-40λ, which can not only suppress the SH mode and high-order transverse modes, but also reduce the coupling between the transverse mode and the SH mode. As an example, the length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction can be 25λ, 30λ, 35λ, etc.

[0105] In some embodiments, the length W of the resonance region 1015 of the series resonance unit 1a in the second direction is 10λ-20λ, so that the resonant frequency of the series resonance unit 1a is controlled within a range where the BO mode does not occur. As an example, the length W of the resonance region 1015 of the series resonance unit 1a in the second direction can be 12λ, 15λ, 19λ, etc.

[0106] As an example, the length W of the resonance region 1015 of the parallel resonance unit 1b in the second direction is 20λ-40λ, and the length W of the resonance region 1015 of the series resonance unit 1a in the second direction is 10λ-20λ, and the length of the suppression portion 102 of the series resonance unit 1a is 0.05λ-0.1λ smaller than the length of the suppression portion 102 of the parallel resonance unit 1b, which can not only suppress the SH mode and the high-order transverse mode, but also reduce the coupling between the transverse mode and the SH mode, and also avoid reducing the quality factor of the filter 10.

[0107] Please refer to Figure 2 , defined in the direction of acoustic wave propagation (first direction), the width of the electrode finger is d, the center-to-center pitch between adjacent first electrode fingers 1013 and second electrode fingers 1014 is p, and the duty cycle is d / p. In some embodiments, the duty cycle of the parallel resonant unit 1b is greater than that of the series resonant unit 1a, which can further suppress the SH mode.

[0108] Specifically, the duty cycle of the parallel resonant unit 1b is 0.03-0.08 greater than that of the series resonant unit 1a. As an example, the duty cycle of the parallel resonant unit 1b may be 0.04, 0.05, 0.07, etc. greater than that of the series resonant unit 1a.

[0109] As an example, the duty cycle of the parallel resonant unit 1b is 0.45-0.65. For example, the duty cycle of the parallel resonant unit 1b can be 0.48, 0.55, or 0.63. The duty cycle of the series resonant unit 1a is 0.4-0.6. For example, the duty cycle of the series resonant unit 1a can be 0.44, 0.50, or 0.55.

[0110] In some embodiments, see Figure 8 The filter 10 further includes a high-acoustic-velocity layer 4, which covers the interdigital transducer structure 101. The thickness H of the high-acoustic-velocity layer 4 in the third direction is 40-70 nm. As an example, the thickness H of the high-acoustic-velocity layer 4 in the third direction can be 45 nm, 50 nm, or 68 nm.

[0111] In this embodiment, please refer to Figure 16 The scattering parameter curve comparison diagram shown in FIG, wherein the curve S61 is the filter passband scattering parameter curve when the thickness H of the high acoustic velocity layer 4 is 70nm, and the curve S62 is the filter passband scattering parameter curve when the thickness H of the high acoustic velocity layer 4 is 50nm. Figure 16 It can be seen from the local G that the spurious mode can be better suppressed by adjusting the thickness of the frequency modulation layer.

[0112] Similarly, in related technologies, for example, in a resonator using a lithium niobate substrate as the piezoelectric substrate 2 and with a cut angle in the YX direction of 150°-180°, the main mode is the SH mode, and the spurious modes that have a greater impact on the filter passband are mainly the Rayleigh mode and the transverse mode.

[0113] In the embodiment of the present application, the length of the suppression portion 102 of the parallel resonant unit 1b is greater than the length of the suppression portion 102 of the series resonant unit 1a, which can achieve the effect of suppressing the transverse mode. In addition, the length W of the resonance region 1015 of the parallel resonant unit 1b in the second direction is greater than the length W of the resonance region 1015 in the second direction of the series resonant unit 1a, which can achieve the effect of suppressing the Rayleigh mode and the high-order transverse mode. The combination of these two effects can suppress the Rayleigh mode and the transverse mode as much as possible, thereby preventing the Rayleigh mode and the transverse mode from coupling with each other, and further eliminating the Rayleigh mode and the transverse mode at the same time.

[0114] As an example, the filter of the embodiment of the present application may be a TC-SAW (Temperature Compensated-Surface Acoustic Wave) filter. It is understandable that the filter of the embodiment of the present application may also be other types of filters, which will not be described in detail here.

[0115] (Example 2)

[0116] One embodiment of the present application provides a filter 10 comprising a plurality of resonant units 1. The resonant units 1 are divided into series resonant units 1a and parallel resonant units 1b. The series resonant units 1a are connected in series to a connection path between a first terminal 20 and a second terminal 30. One end of the parallel resonant unit 1b is connected to the connection path, and the other end of the parallel resonant unit 1b is grounded.

[0117] Each resonant unit 1 includes at least one interdigital transduction structure 101, which includes a first bus bar 1011, a second bus bar 1012, first electrode fingers 1013, and second electrode fingers 1014. The first bus bar 1011 is arranged opposite the second bus bar 1012. There are multiple first electrode fingers 1013 and second electrode fingers 1014, respectively. All first electrode fingers 1013 are connected to the first bus bar 1011, and each first electrode finger 1013 extends toward the second bus bar 1012. All second electrode fingers 1014 are connected to the second bus bar 1012, and each second electrode finger 1014 extends toward the first bus bar 1011. All first electrode fingers 1013 and all second electrode fingers 1014 are alternately arranged in sequence along a first direction, where the first direction is the propagation direction of the sound wave.

[0118] The region where the first electrode fingers 1013 and the second electrode fingers 1014 intersect is a resonance region 1015 . The resonance region 1015 includes a middle region 10151 and an edge region 10152 arranged along a second direction, wherein the second direction is perpendicular to the first direction.

[0119] The duty cycle of the parallel resonant unit 1b is greater than that of the series resonant unit 1a, and the length W of the resonant region 1015 of the parallel resonant unit 1b in the second direction is greater than that of the resonant region 1015 of the series resonant unit 1a in the second direction.

[0120] The filter 10 provided in the embodiment of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes. Taking a filter in which the main mode is the Rayleigh mode and the spurious modes are the SH mode and the transverse mode as an example, the duty cycle of the parallel resonant unit 1b is greater than the duty cycle of the series resonant unit 1a, which can achieve the effect of suppressing the SH mode, and the length W of the resonance region 1015 of the parallel resonant unit 1b in the second direction is greater than the length W of the resonance region 1015 in the second direction of the series resonant unit 1a, which can achieve the effect of suppressing the SH mode and the high-order transverse mode. The superposition of these two effects can not only eliminate the SH mode, but also suppress the transverse mode as much as possible, thereby avoiding the mutual coupling of the SH mode and the transverse mode, thereby further eliminating the SH mode and the transverse mode at the same time.

[0121] It should be noted that the second embodiment is substantially the same as the first embodiment, so the same parts will not be described again here.

[0122] (Example 3)

[0123] One embodiment of the present application provides a filter 10 comprising a plurality of resonant units 1. The resonant units 1 are divided into series resonant units 1a and parallel resonant units 1b. The series resonant units 1a are connected in series to a connection path between a first terminal 20 and a second terminal 30. One end of the parallel resonant unit 1b is connected to the connection path, and the other end of the parallel resonant unit 1b is grounded.

[0124] Each resonant unit 1 includes at least one interdigital transduction structure 101, which includes a first bus bar 1011, a second bus bar 1012, first electrode fingers 1013, and second electrode fingers 1014. The first bus bar 1011 is arranged opposite the second bus bar 1012. There are multiple first electrode fingers 1013 and second electrode fingers 1014, respectively. All first electrode fingers 1013 are connected to the first bus bar 1011, and each first electrode finger 1013 extends toward the second bus bar 1012. All second electrode fingers 1014 are connected to the second bus bar 1012, and each second electrode finger 1014 extends toward the first bus bar 1011. All first electrode fingers 1013 and all second electrode fingers 1014 are alternately arranged in sequence along a first direction, where the first direction is the propagation direction of the sound wave.

[0125] The region where the first electrode fingers 1013 and the second electrode fingers 1014 intersect is a resonance region 1015 . The resonance region 1015 includes a middle region 10151 and an edge region 10152 arranged along a second direction, wherein the second direction is perpendicular to the first direction.

[0126] The resonance unit 1 further includes a suppressing portion 102 provided corresponding to each edge region 10152 .

[0127] The length of the suppression portion 102 of the parallel resonant unit 1b is greater than that of the series resonant unit 1a, and the duty cycle of the parallel resonant unit 1b is greater than that of the series resonant unit 1a.

[0128] The filter 10 provided in the embodiment of the present application can not only suppress multiple spurious modes, but also reduce the coupling of spurious modes, thereby achieving the effect of eliminating multiple spurious modes. Taking a filter in which the main mode is the Rayleigh mode and the spurious modes are the SH mode and the transverse mode as an example, the length of the suppression portion 102 of the parallel resonant unit 1b is greater than the length of the suppression portion 102 of the series resonant unit 1a, which can achieve the effect of suppressing the transverse mode, and the duty cycle of the parallel resonant unit 1b is greater than the duty cycle of the series resonant unit 1a, which can achieve the effect of suppressing the SH mode. The two effects are superimposed, which can suppress the SH mode and the transverse mode as much as possible, thereby avoiding the mutual coupling of the SH mode and the transverse mode, and further eliminating the SH mode and the transverse mode at the same time.

[0129] It should be noted that the third embodiment is substantially the same as the first embodiment, so the same parts will not be described again here.

[0130] An embodiment of the present application further provides a radio frequency front-end module, comprising the filter 10 as described in any one of the first, second and third embodiments.

[0131] The above is only an implementation method of the present application. It should be pointed out that for ordinary technicians in this field, improvements can be made without departing from the creative concept of the present application, but these all fall within the scope of protection of the present application.

Claims

1. A filter, characterized in that: The device comprises a plurality of resonance units, wherein the resonance units are divided into a series resonance unit connected in series on a connection path between a first terminal and a second terminal, and a parallel resonance unit having one end connected to the connection path and the other end grounded; Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction, wherein the first direction is a propagation direction of sound waves; An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction; The resonance unit further includes a suppression portion arranged corresponding to each of the edge regions; Wherein, the length of the resonance region of the parallel resonance unit in the second direction is greater than the length of the resonance region of the series resonance unit in the second direction; The length of the suppression portion of the parallel resonance unit is greater than the length of the suppression portion of the series resonance unit.

2. The filter according to claim 1, wherein A length of the suppression portion of the parallel resonant unit in the first direction is greater than a length of the suppression portion of the series resonant unit in the first direction.

3. The filter according to claim 1, wherein A length of the suppression portion of the parallel resonance unit in a third direction is greater than a length of the suppression portion of the series resonance unit in the third direction, wherein the third direction is perpendicular to the first direction and the second direction.

4. The filter according to claim 1, wherein The length of the suppression portion of the series resonance unit is smaller than the length of the suppression portion of the parallel resonance unit by 0.05λ-0.1λ, where λ is the wavelength of the sound wave.

5. The filter according to claim 1, wherein The resonance region includes a first edge region, a middle region, and a second edge region arranged in sequence along the second direction, and the suppression portion includes a first suppression portion and a second suppression portion, the first suppression portion corresponds to the first edge region, and the first suppression portion is arranged on the first electrode finger and / or the second electrode finger; the second suppression portion corresponds to the second edge region, and the second suppression portion is arranged on the first electrode finger and / or the second electrode finger.

6. The filter according to claim 1, wherein The suppression portion is arranged on at least a portion of the first electrode finger, and the suppression portion is located at least at the end of the first electrode finger facing away from the first bus bar. The suppression portion is arranged on at least a portion of the second electrode finger, and the suppression portion is located at least at the end of the second electrode finger facing away from the second bus bar.

7. The filter according to claim 6, wherein The suppressing portion is protruded from the edge region in a third direction, and the third direction is perpendicular to the first direction and the second direction.

8. The filter according to claim 6, wherein The suppressing portion is protruding from the edge region in the first direction.

9. The filter according to claim 1, wherein The suppressing portion covers the edge region in a third direction, and the third direction is perpendicular to the first direction and the second direction.

10. The filter according to claim 1, wherein The length of the resonance region of the parallel resonance unit in the second direction is 20λ-40λ, where λ is the wavelength of the sound wave.

11. The filter according to claim 1, wherein The length of the resonance region of the series resonance unit in the second direction is 10λ-20λ, where λ is the wavelength of the sound wave.

12. The filter according to claim 1, wherein The duty cycle of the parallel resonance unit is greater than the duty cycle of the series resonance unit.

13. The filter according to claim 12, wherein The duty cycle of the parallel resonance unit is 0.03-0.08 greater than the duty cycle of the series resonance unit.

14. The filter according to claim 12, wherein The duty cycle of the parallel resonance unit is 0.45-0.65, and the duty cycle of the series resonance unit is 0.4-0.

6.

15. The filter according to claim 1, wherein The resonant frequency of the parallel resonance unit is outside the passband of the filter, and the resonant frequency of the series resonance unit is within the passband.

16. The filter according to claim 1, wherein It also includes a high acoustic velocity layer, which covers the interdigital transducer structure. The thickness of the high acoustic velocity layer in the third direction is 40-70 nm, and the third direction is perpendicular to the first direction and the second direction.

17. A filter, characterized in that: The device comprises a plurality of resonance units, wherein the resonance units are divided into a series resonance unit connected in series on a connection path between a first terminal and a second terminal, and a parallel resonance unit having one end connected to the connection path and the other end grounded; Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, and the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction; An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction; The duty cycle of the parallel resonance unit is greater than that of the series resonance unit, and the length of the resonance region of the parallel resonance unit in the second direction is greater than the length of the resonance region of the series resonance unit in the second direction.

18. A filter, characterized in that: The device comprises a plurality of resonance units, wherein the resonance units are divided into a series resonance unit connected in series on a connection path between a first terminal and a second terminal, and a parallel resonance unit having one end connected to the connection path and the other end grounded; Each of the resonant units includes at least one interdigital transduction structure, the interdigital transduction structure including a first bus bar and a second bus bar arranged opposite to each other, and a plurality of first electrode fingers and a plurality of second electrode fingers, the plurality of first electrode fingers being connected to the first bus bar and extending toward the second bus bar, the plurality of second electrode fingers being connected to the second bus bar and extending toward the first bus bar, and the plurality of first electrode fingers and the plurality of second electrode fingers being alternately arranged in sequence along a first direction; An area where the first electrode fingers and the second electrode fingers intersect is a resonance area, and the resonance area includes a middle area and an edge area arranged along a second direction, wherein the second direction is perpendicular to the first direction; The resonance unit further includes a suppression portion arranged corresponding to each of the edge regions; The length of the suppression portion of the parallel resonance unit is greater than the length of the suppression portion of the series resonance unit, and the duty cycle of the parallel resonance unit is greater than the duty cycle of the series resonance unit.

19. A radio frequency front-end module, characterized in that: The filter comprises the filter according to any one of claims 1 to 16, or the filter according to claim 17, or the filter according to claim 18.

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