Filter, radio frequency front-end module and electronic device

Abstract

The application relates to a filter, a radio frequency front end module and electronic equipment. The filter comprises a piezoelectric substrate, a first reflection grating and two interdigital transducers arranged on the surface of the piezoelectric substrate. The two interdigital transducers are arranged on opposite sides of the first reflection grating. The first reflection grating comprises first, second and third fingers connected together. The first and second fingers are arranged on the two sides of the third finger along a first direction. The distance between the third finger adjacent to the first finger and the central axis of the adjacent first finger is a first distance. The distance between the third finger adjacent to the second finger and the central axis of the adjacent second finger is a second distance. The first distance is not equal to the second distance. The filter adjusts the distance between the first, second and third fingers in the first reflection grating shared by the two interdigital transducers, so that the first distance is not equal to the second distance, thereby improving the Q value of the filter.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency, in particular to a filter, a radio frequency front-end module comprising the filter, and an electronic device comprising the radio frequency front-end module. BACKGROUND

[0002] In the field of radio frequency, a filter is usually composed of a piezoelectric substrate and a plurality of interdigital transducers. Through the cooperation of each interdigital transducer and the piezoelectric substrate, the mutual conversion between electrical signals and acoustic wave signals is realized. In order to constrain the acoustic surface wave generated by the interdigital transducer when working, a reflective grating is arranged on the opposite side of each interdigital transducer to form a resonator.

[0003] In the related art, in order to realize the miniaturization of the filter, two resonators usually share one reflective grating. When the parameters of the two resonators are different, the common reflective grating will cause the mutual influence of the main modes of the two resonators, thereby causing the deterioration of the quality factor (Q value) of the filter. SUMMARY

[0004] In view of the deficiencies of the above-mentioned related art, the purpose of the present application is to provide a scheme for improving the Q value of the filter, which specifically includes the following technical solutions:

[0005] In a first aspect, the embodiments of the present application provide a filter, comprising a piezoelectric substrate, and a first reflective grating and two interdigital transducers arranged on the surface of the piezoelectric substrate, the two interdigital transducers being arranged on opposite sides of the first reflective grating.

[0006] The first reflective grating comprises a first finger, a second finger and a third finger connected in series, and the first finger and the second finger are arranged on the two sides of the third finger along a first direction; wherein,

[0007] The distance between the third finger adjacent to the first finger and the center axis of the adjacent first finger is a first distance, and the distance between the third finger adjacent to the second finger and the center axis of the adjacent second finger is a second distance, and the first distance and the second distance are not equal.

[0008] The filter of the present application arranges the two interdigital transducers on opposite sides of the first reflective grating, so that the first reflective grating can simultaneously constrain the propagation range of the acoustic surface wave generated by the two interdigital transducers when working, thereby improving the performance of the two interdigital transducers while facilitating the miniaturization of the filter of the present application.

[0009] The filter provided by the present application also adjusts the finger spacing of the first finger strip, the second finger strip and the third finger strip in the first reflective grating, so that the first spacing between the adjacent first finger strip and the third finger strip is not equal to the second spacing between the adjacent second finger strip and the third finger strip. In this way, the mutual influence of the surface acoustic waves generated by the two interdigital transducers when working is avoided, and the Q value of the filter provided by the present application is improved.

[0010] In a second aspect, the embodiments of the present application provide a filter, comprising a piezoelectric substrate, and a first reflective grating and two interdigital transducers arranged on the surface of the piezoelectric substrate, the two interdigital transducers being arranged on opposite sides of the first reflective grating; the first reflective grating comprises a first finger strip, a second finger strip and a third finger strip connected in series, the first finger strip and the second finger strip being arranged on the two sides of the third finger strip along a first direction; wherein the number of the first finger strips is less than the number of the second finger strips, and the number of the first finger strips is greater than or equal to the number of the third finger strips.

[0011] The filter provided by the present application can block the mutual influence of the surface acoustic waves generated by the two interdigital transducers when working by arranging a relatively small number of third finger strips between the plurality of first finger strips and the plurality of second finger strips, while ensuring the overall size of the first reflective grating, so as to improve the Q value of the filter provided by the present application.

[0012] In a third aspect, the embodiments of the present application provide a radio frequency front-end module, comprising the filter of the first aspect or the second aspect.

[0013] In a fourth aspect, the embodiments of the present application provide an electronic device, comprising the radio frequency front-end module.

[0014] It can be understood that the radio frequency front-end module provided by the third aspect of the present application and the electronic device provided by the fourth aspect of the present application adopt the surface acoustic wave device provided by the first aspect and the second aspect of the present application. The radio frequency front-end module and the electronic device of the present application also have a better Q value. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a structural schematic diagram of an electronic device provided by an embodiment of the present application;

[0016] Figure 2 FIG. 2 is a structural schematic diagram of a radio frequency front-end module provided by an embodiment of the present application;

[0017] Figure 3 FIG. 3 is a structural schematic diagram of a filter provided by an embodiment of the present application;

[0018] Figure 4 FIG. 4 is a top view structural schematic diagram of the filter provided by an embodiment of the present application;

[0019] Figure 5A partial structure schematic diagram of a filter provided in an embodiment of the present application;

[0020] Figure 6 Another top view structure schematic diagram of a filter provided in an embodiment of the present application;

[0021] Figure 7 Another partial structure schematic diagram of a filter provided in an embodiment of the present application;

[0022] Figure 8 Still another top view structure schematic diagram of a filter provided in an embodiment of the present application;

[0023] Figure 9 Still another partial structure schematic diagram of a filter provided in an embodiment of the present application;

[0024] Figure 10 Still another partial structure schematic diagram of a filter provided in an embodiment of the present application;

[0025] Figure 11 Still another partial structure schematic diagram of a filter provided in an embodiment of the present application;

[0026] Figure 12 A partial enlarged structure schematic diagram of a filter provided in an embodiment of the present application;

[0027] Figure 13 Another partial enlarged structure schematic diagram of a filter provided in an embodiment of the present application;

[0028] Figure 14 Another structure schematic diagram of a filter provided in an embodiment of the present application;

[0029] Figure 15 An arrangement structure schematic diagram of a filter provided in an embodiment of the present application;

[0030] Figure 16 A partial top view structure schematic diagram of a filter provided in an embodiment of the present application;

[0031] Figure 17 A conductance curve comparison diagram of Comparative Example 1 and Reference Example 1 in the related art;

[0032] Figure 18 A conductance curve comparison diagram of Comparative Example 2 and Reference Example 1 in the related art;

[0033] Figure 19 A conductance curve comparison diagram of Comparative Example 3 and Reference Example 1 in the related art;

[0034] Figure 20A comparison chart of the conductance curves of Example 1 and Reference Example 1 provided in an embodiment of the present application;

[0035] Figure 21 A comparison chart of the conductance curves of Example 2 and Reference Example 1 provided in an embodiment of the present application;

[0036] Figure 22 A comparison chart of the conductance curves of Example 3 and Reference Example 1 provided in an embodiment of the present application;

[0037] Figure 23 A comparison chart of the Q value curves of Comparative Example 1 and Reference Example 1 in the related art;

[0038] Figure 24 A comparison chart of the Q value curves of Comparative Example 2 and Reference Example 1 in the related art;

[0039] Figure 25 A comparison chart of the Q value curves of Comparative Example 3 and Reference Example 1 in the related art;

[0040] Figure 26 A comparison chart of the Q value curves of Example 1 and Reference Example 1 provided in an embodiment of the present application;

[0041] Figure 27 A comparison chart of the Q value curves of Example 2 and Reference Example 1 provided in an embodiment of the present application;

[0042] Figure 28 A comparison chart of the Q value curves of Example 3 and Reference Example 1 provided in an embodiment of the present application;

[0043] Figure 29 A comparison chart of the admittance curves of Comparative Example 1 to Comparative Example 3 and Reference Example 1 in the related art;

[0044] Figure 30 A comparison chart of the admittance curves of Example 1 to Example 3 and Reference Example 1 provided in an embodiment of the present application;

[0045] Figure 31 A comparison chart of the conductance curves of Comparative Example 4 and Reference Example 2 in the related art;

[0046] Figure 32 A comparison chart of the conductance curves of Comparative Example 5 and Reference Example 2 in the related art;

[0047] Figure 33 A comparison chart of the conductance curves of Comparative Example 6 and Reference Example 2 in the related art;

[0048] Figure 34 A comparison chart of the conductance curves of Example 4 and Reference Example 2 provided in an embodiment of the present application;

[0049] Figure 35 A comparison chart of the conductance curve of Example 5 and Reference Example 2 provided in one embodiment of the present application;

[0050] Figure 36 A comparison chart of the conductance curve of Example 6 and Reference Example 2 provided in one embodiment of the present application;

[0051] Figure 37 A comparison chart of the conductance curve of Example 7 and Reference Example 2 provided in one embodiment of the present application;

[0052] Figure 38 A comparison chart of the Q value curve of Comparative Example 4 and Reference Example 2 in the related art;

[0053] Figure 39 A comparison chart of the Q value curve of Comparative Example 5 and Reference Example 2 in the related art;

[0054] Figure 40 A comparison chart of the Q value curve of Comparative Example 6 and Reference Example 2 in the related art;

[0055] Figure 41 A comparison chart of the Q value curve of Example 4 and Reference Example 2 provided in one embodiment of the present application;

[0056] Figure 42 A comparison chart of the Q value curve of Example 5 and Reference Example 2 provided in one embodiment of the present application;

[0057] Figure 43 A comparison chart of the Q value curve of Example 6 and Reference Example 2 provided in one embodiment of the present application;

[0058] Figure 44 A comparison chart of the Q value curve of Example 7 and Reference Example 2 provided in one embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to facilitate the understanding of the present application, a more comprehensive description of the present application will be provided below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0060] The following description of the embodiments is provided as an example to illustrate the present application which can be implemented. The numbers of components in the present application, such as "first", "second", etc., are only used to distinguish the described objects, and do not have any sequential or technical meaning. The "connection" and "coupling" in the present application, unless otherwise specified, include direct and indirect connections (couplings). The direction terms used in the present application, such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", etc., are only the directions of the attached drawings, and therefore, the direction terms used are for better, clearer illustration and understanding of the present application, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, cannot be understood as limiting the present application.

[0061] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "coupling" should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the drawings are used to distinguish different objects, and are not used to describe a specific order. In addition, the terms "include", "may include", "contain" or "may contain" used in the present application represent the existence of the corresponding functions, operations, elements, etc. disclosed, and do not limit other one or more functions, operations, elements, etc. In addition, the terms "include" or "contain" represent the existence of the corresponding features, numbers, steps, operations, elements, components or combinations thereof disclosed in the specification, and do not exclude the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations thereof, and are intended to cover non-exclusive inclusion.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application.

[0063] Please refer to Figure 1 The structure schematic diagram of the electronic device 300 provided in an embodiment of the present application is shown.

[0064] As Figure 1As shown, the electronic device 300 includes a transceiver, an antenna, and the radio frequency front end module 200 connected between the transceiver and the antenna, for amplifying the radio frequency signal output by the transceiver to obtain sufficient radio frequency output power, and transmitting the radio frequency signal amplified to the antenna, so as to be radiated out through the antenna; and / or, for amplifying the relatively weak radio frequency signal received by the antenna with a lower noise factor, and transmitting the radio frequency signal to the transceiver.

[0065] For example, the electronic device 300 includes at least one of a computer, a mobile phone, a tablet computer, a smart watch, and a navigator, which are not particularly limited in the present application.

[0066] Please refer to Figure 2 As shown, the radio frequency front end module 200 provided in an embodiment of the present application is shown in the structural schematic diagram.

[0067] The radio frequency front end module is an element integrating one or more than one discrete device such as a radio frequency switch, a low noise amplifier, a filter, a duplexer, and a power amplifier into an independent module, so as to improve the integration and hardware performance, and miniaturize the volume.

[0068] As Figure 2 As shown, the radio frequency front end module 200 of the embodiment of the present application includes a signal end 201, a switch 202, an amplifier 203, and a filter 100. The signal end 201 is used to receive an external signal or transmit a radio frequency signal. For example, the signal end 201 can be a port for connecting an antenna, also known as an antenna port. The radio frequency front end module can be connected to the antenna in the electronic device through the signal end 201, so as to receive or transmit a radio frequency signal through the antenna.

[0069] The switch 202 is communicatively connected between the signal end 201 and the filter 100, so as to control the signal transmission between the signal end 201 and the filter 100.

[0070] The number of the amplifier 203 can be one or more. Optionally, the amplifier 203 can include at least one low noise amplifier, or one or more power amplifiers, or at least one power amplifier and at least one low noise amplifier.

[0071] The number of the filter 100 can also be one or more. When there are multiple filters 100, different filters 100 can be used to filter signals on different signal transmission paths, wherein the different signal transmission paths can be the same frequency band transmission path and reception path, or different frequency band transmission paths and reception paths, or different frequency band transmission paths, or different frequency band reception paths.

[0072] The switch 202 can include a plurality of switch paths, and a common end of the plurality of switch paths is connected with the signal terminal 201 to switch the filter on different signal transmission paths to be connected with the signal terminal 201.

[0073] When the amplifier 203 is a low noise amplifier, the filter 100 is configured to receive an external signal received by the signal terminal 201 when the switch 202 is closed, and perform filtering processing on the external signal to output a signal with a preset frequency. The amplifier 203 is electrically connected with the filter 100 to amplify the signal processed by the filter 100 and output the signal to a subsequent stage (for example, a receiver in an electronic device).

[0074] When the amplifier 203 is a power amplifier, the filter 100 is configured to receive a radio frequency signal amplified by the amplifier 203, and perform filtering processing on the received radio frequency signal, and then transmit the radio frequency signal processed by the filtering processing to the signal terminal 201 through the closed switch 202.

[0075] In an embodiment, the radio frequency front end module 200 includes a plurality of filters 100, and at least two of the plurality of filters 100 can be integrated together to form a diplexer or a multiplexer. That is, the radio frequency front end module 200 further includes a multiplexer, and the multiplexer includes a plurality of filters 100.

[0076] It is worth mentioning that in the embodiments and subsequent embodiments of the present application, the number of structures is plural, which means that the number of structures is two or more.

[0077] In an embodiment, the filter 100 provided by the present application includes a piezoelectric substrate 10, a plurality of interdigital transducers 20, and a first reflective grating 30. The plurality of interdigital transducers 20 are arranged on the surface of the piezoelectric substrate 10 with the first reflective grating 30 in between. Specifically, the number of the interdigital transducers 20 is at least two, and at least two of the interdigital transducers 20 are arranged on opposite sides of the first reflective grating 30.

[0078] For example, as shown in Figure 3 and Figure 4 , the filter 100 provided by an embodiment of the present application includes a piezoelectric substrate 10, a plurality of interdigital transducers 20, and a first reflective grating 30. The plurality of interdigital transducers 20 are arranged on the surface of the piezoelectric substrate 10 with the first reflective grating 30 in between. Specifically, the number of the interdigital transducers 20 is at least two, and at least two of the interdigital transducers 20 are arranged on opposite sides of the first reflective grating 30. Figure 3 is a structural schematic diagram of the filter 100 provided by an embodiment of the present application, Figure 4 is a top view structural schematic diagram of the filter 100 provided by an embodiment of the present application.

[0079] As shown in Figure 3 and Figure 4 , in the filter 100, the number of the interdigital transducers 20 is two.

[0080] For ease of description, in the embodiments and subsequent embodiments of the present application, two adjacent interdigital transducers 20 arranged on the surface of the piezoelectric substrate 10 are described.

[0081] Please see the partial structure diagram of the filter 100 provided in an embodiment of the present application shown in Figure 5

[0082] As shown in Figure 5 Each interdigital transducer 20 includes two bus bars 21 arranged in parallel and at intervals, and a plurality of electrode fingers 22 arranged in parallel and at intervals. One of the two bus bars 21 is used to receive an external signal, and the other of the two bus bars 21 is used to output a signal. The plurality of electrode fingers 22 are located between the two bus bars 21. Some of the plurality of electrode fingers 22 are connected to one bus bar 21, and the other of the plurality of electrode fingers 22 are connected to the other bus bar 21.

[0083] For ease of description, the bus bar 21 used to receive an external signal is defined as a first bus bar 21a, and the bus bar 21 used to output a signal is defined as a second bus bar 21b. The electrode finger 22 connected to the first bus bar 21a is defined as a first electrode 221, and the electrode finger 22 connected to the second bus bar 21b is defined as a second electrode 222.

[0084] Specifically, the first electrodes 221 and the second electrodes 222 are arranged alternately along a first direction 001. The first electrodes 221 and the second electrodes 222 both extend along a second direction 002. Specifically, as shown in Figure 4 Along the first direction 001, there is one second electrode 222 between any two adjacent first electrodes 221, and there is one first electrode 221 between any two adjacent second electrodes 222.

[0085] The first direction 001 is the extension direction of the bus bar, that is, the first bus bar 21a and the second bus bar 21b both extend along the first direction 001. The second direction 002 intersects the first direction 001. For example, the second direction 002 can be perpendicular to the first direction 001, so that each electrode finger 22 has a 90° angle with the bus bar connected thereto. For example, the second direction 002 can also be not perpendicular to the first direction 001, so that each electrode finger 22 has an angle greater than 90° with the bus bar connected thereto.

[0086] In the embodiment of the present application, when an external excitation signal is loaded on the interdigital transducer 20, the interdigital transducer 20 converts the electrical signal into a surface acoustic wave, the surface acoustic wave propagates along the surface of the piezoelectric substrate 10 and is reflected by the reflection grating, and then is converted into an electrical signal by the interdigital transducer 20 for output.

[0087] ​The surface acoustic wave is used to realize the frequency selection function and the signal processing function of the filter 100. In the surface acoustic wave propagation process, the main propagation direction of the surface acoustic wave is the first direction 001. However, in the actual process, due to the edge effect and the acoustic wave diffraction effect, the propagation direction of the surface acoustic wave formed on the surface of the piezoelectric substrate 10 can also be other directions. In an embodiment, the surface acoustic wave propagating towards the remaining directions is absorbed by the sound-absorbing material (not shown in the figure).

[0088] It can be understood that the present application can be applied to high-Q piezoelectric thin film on insulator (POISAW filter), conventional surface acoustic wave filter (NSAW filter), temperature compensated surface acoustic wave filter (TCSAW filter), and filter devices formed by interconnecting them in a certain topology, and other devices including interdigital transducers, which are not limited by the present application.

[0089] In an embodiment, the first direction 001 is the arrangement direction of the two interdigital transducers 20.

[0090] In the embodiment of the present application, along the first direction 001, the first reflective grating 30 is located on one side of the interdigital transducer 20. When the surface acoustic wave generated by the interdigital transducer 20 propagates along the first direction 001, it will be transmitted into the first reflective grating 30. The first reflective grating 30 is used to reflect the surface acoustic wave propagating into the first reflective grating 30, so as to constrain the surface acoustic wave generated by the interdigital transducer 20.

[0091] Since the first reflective grating 30 is located between the two interdigital transducers 20, it can be understood that the first reflective grating 30 can simultaneously reflect the surface acoustic waves generated by the two interdigital transducers 20, and constrain the propagation range of the surface acoustic waves generated by the two interdigital transducers 20, thereby improving the performance of the two interdigital transducers. Further improve the working performance of the filter of the present application.

[0092] Meanwhile, compared with the scheme in the related art that each interdigital transducer independently uses a pair of the same reflective grating for reflection and different interdigital transducers use different reflective gratings, the filter 100 of the present application uses one first reflective grating 30 to constrain the surface acoustic waves generated by the two interdigital transducers 20, which is also conducive to reducing the spacing between the two interdigital transducers 20, and is conducive to the miniaturization of the filter 100 of the present application.

[0093] Please refer to Figure 6 and Figure 7 , wherein Figure 6 is another top view structural schematic diagram of the filter 100 provided in an embodiment of the present application, Figure 7 is another partial structural schematic diagram of the filter 100 provided in an embodiment of the present application.

[0094] As shown in Figure 6 and Figure 7 The first reflective grating 30 includes a first finger 31, a second finger 32 and a third finger 33. The first finger 31 and the second finger 32 are arranged on two sides of the third finger 33 along the first direction 001. In the embodiment, one of the two interdigital transducers 20 is located on one side of the third finger 33 with the first finger 31, and the other of the two interdigital transducers 20 is located on the other side of the third finger 33 with the second finger 32.

[0095] For ease of description, the interdigital transducer 20 on the same side of the first finger 31 is defined as the first interdigital transducer 20a. The interdigital transducer 20 on the same side of the second finger 32 is defined as the second interdigital transducer 20b.

[0096] As shown in Figure 6 and Figure 7 The acoustic surface wave generated by the first interdigital transducer 20a propagates towards the first finger 31. When the main mode of the acoustic surface wave is transmitted to the first finger 31, the first finger 31 is used to reflect the main mode. Thus, the main mode of the acoustic surface wave generated by the first interdigital transducer 20a is confined in the first interdigital transducer 20a.

[0097] The acoustic surface wave generated by the second interdigital transducer 20b propagates towards the second finger 32. When the main mode of the acoustic surface wave is transmitted to the second finger 32, the second finger 32 is used to reflect the main mode. Thus, the main mode of the acoustic surface wave generated by the second interdigital transducer 20b is confined in the second interdigital transducer 20b.

[0098] In an embodiment, the distance between the third finger 33 adjacent to the first finger 31 and the central axis of the adjacent first finger 31 is a first distance D1, the distance between the third finger 33 adjacent to the second finger 32 and the central axis of the adjacent second finger 32 is a second distance D2, and the first distance D1 is not equal to the second distance D2.

[0099] It is worth mentioning that the number of the first finger 31, the second finger 32 and the third finger 33 can be one or more. The third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 means that one of the third fingers 33 closest to the first finger 31 and one of the first fingers 31 closest to the third finger 33, which are also called "adjacent third finger 33 and first finger 31" hereinafter for convenience. Similarly, the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 means that one of the third fingers 33 closest to the second finger 32 and one of the second fingers 32 closest to the third finger 33, which are also called "adjacent third finger 33 and second finger 32" hereinafter for convenience.

[0100] The wavelength range of the surface acoustic wave reflected by the reflection grating is related to the interval between the center axes of the adjacent fingers in the reflection grating. When the surface acoustic wave propagates to the fingers of the reflection grating, the reflection grating mainly reflects the surface acoustic wave with a wavelength matched with the interval between the center axes of the adjacent two fingers, and part of the surface acoustic wave that does not match is blocked by the fingers, and the other part directly propagates outward through the reflection grating and gradually attenuates with the increase of the propagation distance.

[0101] In the embodiment of the present application, the first finger 31 is configured to match the main mode of the first interdigital transducer 20a, and the second finger 32 is configured to match the main mode of the second interdigital transducer 20b.

[0102] It is worth mentioning that the main mode described in the embodiments of the present application and subsequent embodiments refers to the part of the surface acoustic wave matched with the main mode frequency in the surface acoustic wave.

[0103] In Figure 6 and Figure 7 In the legends shown in the figures, the number of the first finger 31, the second finger 32 and the third finger 33 is one. Correspondingly, the third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 are adjacent third finger 33 and first finger 31, and the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 are adjacent third finger 33 and second finger 32.

[0104] In the embodiment of the present application, when the first interdigital transducer 20a works, the first finger 31 of the first reflection grating 30 can reflect the main mode in the surface acoustic wave generated by the first interdigital transducer 20a into the first interdigital transducer 20a.

[0105] In the embodiment of the present application, by setting the first distance D1 and the second distance D2 to be unequal, the mutual influence of the main modes not reflected by the first finger 31 and the second finger 32 can be avoided, thereby ensuring the use performance of the filter 100 of the present application and improving the Q value of the filter 100 of the present application.

[0106] Similarly, when the second interdigital transducer 20b is working, by setting the first distance D1 and the second distance D2 to be unequal, the performance of the second interdigital transducer 20b can also be ensured, thereby ensuring the performance of the filter 100 of the present application and improving the Q value of the filter 100 of the present application.

[0107] Based on the above description, it is worth mentioning that when the number of one or more of the first finger 31, the second finger 32 and the third finger 33 is multiple, in the description of the adjacent first finger 31 and the third finger 33, the third finger 33 refers to one third finger 33 adjacent to the first finger 31, and the first finger 31 refers to the first finger 31 having the smallest distance from the third finger 33, that is, the first finger 31 adjacent to the third finger 33.

[0108] In the description of the adjacent second finger 32 and the third finger 33, the third finger 33 refers to one third finger 33 adjacent to the second finger 32, and the second finger 32 refers to the second finger 32 having the smallest distance from the third finger 33, that is, the second finger 32 adjacent to the third finger 33.

[0109] Please see Figure 8 and Figure 9 , wherein Figure 8 is another top view structural schematic diagram of the filter 100 provided in an embodiment of the present application, Figure 9 is another partial structural schematic diagram of the filter 100 provided in an embodiment of the present application.

[0110] As shown in Figure 8 and Figure 9 , the number of the first finger 31 and the second finger 32 is multiple, the number of the third finger 33 is one, and the multiple first fingers 31, the third finger 33 and the multiple second fingers 32 are arranged at intervals along the first direction 001.

[0111] It can be understood that the arrangement of the plurality of first finger strips 31 can increase the reflection efficiency of the first finger strips 31 to the surface acoustic wave generated by the first interdigital transducer 20a when the first interdigital transducer 20a is working, thereby improving the performance of the first interdigital transducer 20a and increasing the Q value of the first interdigital transducer 20a. The arrangement of the plurality of second finger strips 32 can also increase the reflection efficiency of the second finger strips 32 to the surface acoustic wave generated by the second interdigital transducer 20b when the second interdigital transducer 20b is working, thereby improving the performance of the second interdigital transducer 20b and increasing the Q value of the second interdigital transducer 20b. Thus, the Q value of the filter 100 of the present application is increased.

[0112] In the embodiment of the present application, the spacing between the center axes of two adjacent first finger strips 31 is a first finger spacing F1, and the spacing between the center axes of two adjacent second finger strips 32 is a second finger spacing F2. The first finger spacing F1 is used to define the reflection frequency of the first reflection grating 30 to the surface acoustic wave generated by the first interdigital transducer 20a when the first interdigital transducer 20a is working, and the second finger spacing F2 is used to define the reflection frequency of the first reflection grating 30 to the surface acoustic wave generated by the second interdigital transducer 20b when the second interdigital transducer 20b is working.

[0113] The difference between 2 times of the first spacing D1 and the first finger spacing F1 is defined as a third finger spacing F3, i.e., D1 = 1 / 2(F1+F3). And / or, the difference between 2 times of the second spacing D2 and the second finger spacing F2 is defined as the third finger spacing F3, i.e., D2 = 1 / 2(F2+F3). Wherein, the third finger spacing F3 is greater than the first finger spacing F1 and the second finger spacing F2.

[0114] That is, the third finger strip 33 has a relatively large spacing with the first finger strip 31 and the second finger strip 32, which on the one hand makes the main mode not reflected by the first finger strip 31 gradually attenuate before propagating to the third finger strip 33, thereby reducing the mutual influence of the main modes of the two interdigital transducers 20. On the other hand, the relatively large spacing also makes the part of the main mode generated by the two interdigital transducers 20 that passes through the first finger strip 31 and the second finger strip 32 not easily pass through the third finger strip 33 to the other interdigital transducer 20, thereby making the third finger strip 33 be able to block the mutual influence of the surface acoustic waves when the two interdigital transducers 20 are working. Further, the Q value of the filter 100 of the present application is increased.

[0115] In an embodiment, the difference between 2 times of the first spacing D1 and the first finger spacing F1 is equal to the difference between 2 times of the second spacing D2 and the second finger spacing F2.

[0116] Please refer to Figure 10 for another partial structural schematic diagram of the filter 100 provided in an embodiment of the present application.

[0117] As Figure 10As shown, the number of the first fingers 31, the second fingers 32 and the third fingers 33 are all multiple, the multiple first fingers 31, the multiple third fingers 33 and the multiple second fingers 32 are arranged at intervals along the first direction 001. The interval between the central axes of two adjacent first fingers 31 is the first finger interval F1, the interval between the central axes of two adjacent second fingers 32 is the second finger interval F2, the interval between the central axes of two adjacent third fingers 33 is the third finger interval F3, and the third finger interval F3 is greater than the first finger interval F1 and the second finger interval F2.

[0118] Along the first direction 001, the multiple first fingers 31 are arranged at intervals, the multiple second fingers 32 are arranged at intervals, and the multiple third fingers 33 are arranged at intervals. Among them, the first finger interval F1 corresponding to the multiple first fingers 31 arranged at intervals is usually set to match the main mode of the first IDT 20a. That is, the main mode in the surface acoustic wave generated when the first IDT 20a works will be reflected by the multiple first fingers 31, thereby improving the Q value of the first IDT 20a.

[0119] The second finger interval F2 corresponding to the multiple second fingers 32 arranged at intervals is usually set to match the main mode of the second IDT 20b. That is, the part of the surface acoustic wave matching the frequency of the main mode in the surface acoustic wave generated when the second IDT 20b works will be reflected by the multiple second fingers 32, thereby improving the Q value of the second IDT 20b.

[0120] The multiple third fingers 33 arranged at intervals increase the interval between the first fingers 31 and the second fingers 32, and reduce the influence of the main mode not reflected by the first fingers 31 and the second fingers 32 on the two IDTs 20. At the same time, the mutual cooperation of the multiple third fingers 33 further improves the blocking efficiency of the main mode of the surface acoustic wave passing through the first fingers 31 and the second fingers 32, and further avoids the possibility of the main mode of each IDT 20 working propagating to the IDT 20 on the other side. Thus, the Q value of the filter of the present application is improved.

[0121] In an embodiment, the first interval D1 is equal to half of the sum of the third finger interval F3 and the first finger interval F1; and the second interval D2 is equal to half of the sum of the third finger interval F3 and the second finger interval F2.

[0122] For the surface acoustic wave, when the surface acoustic wave propagates on the surface of the piezoelectric substrate 10, the surface acoustic wave will gradually attenuate with the increase of the propagation time without the action of other structures. In the embodiment of the present application, when the main mode in the surface acoustic wave generated by the IDT 20 propagates between the first fingers 31 and the third fingers 33 and between the second fingers 32 and the third fingers 33, the intensity of the main mode will gradually decrease.

[0123] It can be understood that the greater the first distance D1 and the second distance D2, the lower the intensity of the main mode when propagating to the third finger strip 33, and the smaller the mutual influence between the main modes of the two interdigital transducers 20. The greater the first distance D1 and the second distance D2, the greater the size of the first reflective grating 30, and the greater the distance between the first interdigital transducer 20a and the second interdigital transducer 20b, which is not conducive to the miniaturization of the filter 100 of the present application.

[0124] That is, the filter 100 of the present application limits the size of the first distance D1 and the second distance D2 to facilitate the miniaturization of the filter 100 of the present application, while improving the Q value of the filter 100 of the present application.

[0125] In an embodiment, the width of the third finger strip 33 is greater than the width of the second finger strip 32. That is, the first reflective grating 30 of the filter 100 of the present application adjusts the width of the third finger strip 33 to adjust the size relationship between the third finger distance F3 and the second finger distance F2. Thus, the third finger strip 33 blocks the surface acoustic wave generated by the second interdigital transducer 20b when it is working, thereby improving the Q value of the filter 100 of the present application.

[0126] In an embodiment, the width of the third finger strip 33 is greater than the width of the first finger strip 31. That is, the first reflective grating 30 of the filter 100 of the present application adjusts the width of the third finger strip 33 to adjust the size relationship between the third finger distance F3 and the first finger distance F1. Thus, the third finger strip 33 blocks the surface acoustic wave generated by the first interdigital transducer 20a when it is working, thereby improving the Q value of the filter 100 of the present application.

[0127] Please refer to Figure 11 for another partial structure diagram of the filter 100 provided in an embodiment of the present application.

[0128] As shown in Figure 11 , along the first direction 001, the gap size between adjacent two first finger strips 31 is the first gap size G1, and the gap size between the third finger strip 33 adjacent to the first finger strip 31 and the adjacent first finger strip 31 is greater than the first gap size G1.

[0129] That is, the first reflective grating 30 of the filter 100 of the present application adjusts the adjacent third finger strip 33 and the first finger strip 31 to adjust the size relationship between the third finger distance F3 and the first finger distance F1. Thus, the third finger strip 33 blocks the surface acoustic wave generated by the first interdigital transducer 20a when it is working, thereby improving the Q value of the filter 100 of the present application.

[0130] In an embodiment, the gap size between the adjacent two second fingers 32 is a second gap size G2 along the first direction 001, and the gap size between the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 is greater than the second gap size G2.

[0131] That is, the first reflector 30 of the filter 100 of the present application adjusts the gap size between the adjacent third finger 33 and the second finger 32 to adjust the size relationship between the third finger spacing F3 and the second finger spacing F2, so as to ensure the blocking effect of the third finger 33 on the surface acoustic wave generated by the second IDT 20b during operation, and improve the Q value of the filter 100 of the present application.

[0132] In an embodiment, the width of the third finger 33 is greater than the width of the first finger 31, and the width of the third finger 33 is greater than the width of the second finger 32. The gap size between the third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is greater than the first gap size G1 along the first direction 001, and the gap size between the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 is greater than the second gap size G2.

[0133] In an embodiment, the width of the third finger 33, the width of the first finger 31, and the width of the second finger 32 are equal. The gap size between the third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is greater than the first gap size G1 along the first direction 001, and the gap size between the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 is greater than the second gap size G2.

[0134] In an embodiment, the width of the third finger 33 is greater than the width of the first finger 31, and the width of the third finger 33 is greater than the width of the second finger 32. The gap size between the third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is equal to the first gap size G1 along the first direction 001, and the gap size between the third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 is equal to the second gap size G2.

[0135] In an embodiment, the ratio of the third finger spacing F3 to the first finger spacing F1 is greater than or equal to 1.01. That is, the filter 100 of the present application controls the ratio of the third finger spacing F3 to the first finger spacing F1 to make the intensity of the main mode propagating to the third finger 33 relatively weak, reduce the mutual influence of the main modes of the two IDTs 20, and improve the Q value of the filter 100 of the present application.

[0136] Meanwhile, the ratio of the third finger spacing F3 to the first finger spacing F1 is greater than or equal to 1.01, which also ensures the blocking effect of the third finger strip 33 on the main mode of the two interdigital transducers 20. Thus, the surface acoustic waves generated by the two interdigital transducers 20 when working will not affect each other, and the Q value of the filter 100 of the present application is improved.

[0137] In an embodiment, the third finger spacing F3 is less than or equal to 1.04 times the first finger spacing F1, so as to control the first spacing D1 and the second spacing D2, reduce the overall size of the first reflection grating 30, and facilitate the miniaturization of the filter 100 of the present application.

[0138] In an embodiment, the third finger spacing F3 is less than or equal to 1.1 times the first finger spacing F1.

[0139] In an embodiment, referring back to Figure 4 and Figure 5 , the first interdigital transducer 20a includes a plurality of first electrode fingers 22a, the finger spacing of the first interdigital transducer 20a is equal to the first finger spacing F1, and the spacing between the first finger strip 31 adjacent to the first interdigital transducer 20a and the central axis of the adjacent first electrode finger 22a is equal to the first finger spacing F1.

[0140] Since the frequency of the main mode of the first interdigital transducer 20a is determined by the finger spacing of the two adjacent first electrode fingers 22a in the first interdigital transducer 20a, the filter 100 of the present application sets the finger spacing of the two adjacent first electrode fingers 22a and the spacing between the first finger strip 31 adjacent to the first interdigital transducer 20a and the central axis of the adjacent first electrode finger 22a to the first finger spacing F1, so as to ensure that the plurality of first finger strips 31 can reflect the main mode of the first interdigital transducer 20a.

[0141] In an embodiment, as shown in Figure 4 and Figure 5 , the second interdigital transducer 20b includes a plurality of second electrode fingers 22b, the finger spacing of the second interdigital transducer 20b is equal to the second finger spacing F2, and the spacing between the second finger strip 32 adjacent to the second interdigital transducer 20b and the central axis of the adjacent second electrode finger 22b is equal to the second finger spacing F2.

[0142] Since the frequency of the main mode of the second interdigital transducer 20b is determined by the finger spacing of the two adjacent second electrode fingers 22b in the second interdigital transducer 20b, the filter 100 of the present application sets the finger spacing of the two adjacent second electrode fingers 22b and the spacing between the second finger strip 32 adjacent to the second interdigital transducer 20b and the central axis of the adjacent second electrode finger 22b to the second finger spacing F2, so as to ensure that the plurality of second finger strips 32 can reflect the main mode of the second interdigital transducer 20b.

[0143] In an embodiment, the first interdigital transducer 20a and the second interdigital transducer 20b have different finger spacings. In an example embodiment, the first finger spacing F1 is greater than the second finger spacing F2. That is, the first reflector 30 is capable of reflecting the surface acoustic waves of the two interdigital transducers 20 having different dominant modes. Thus, the operating range of the filter 100 is improved.

[0144] In an embodiment, the number of the first fingers 31 is a plurality, the number of the second fingers 32 is a plurality, and the number of the first fingers 31 and the number of the second fingers 32 are both greater than or equal to the number of the third fingers 33.

[0145] The plurality of the first fingers 31 is configured to reflect the dominant mode of the surface acoustic wave generated by the first interdigital transducer 20a, and the plurality of the second fingers 32 is configured to reflect the dominant mode of the surface acoustic wave generated by the second interdigital transducer 20b.

[0146] The more the number of the fingers of the reflector, the better the reflection effect of the reflector on the corresponding surface acoustic wave. In the embodiment, the filter 100 is configured to have a relatively large number of the first fingers 31 and the second fingers 32, so as to improve the reflection effect of the first reflector 30 on the surface acoustic waves generated by the first interdigital transducer 20a and the second interdigital transducer 20b, thereby ensuring the performance of the filter 100.

[0147] In an embodiment, the number of the first fingers 31 is less than or equal to the number of the second fingers 32. The smaller the finger spacing of the interdigital transducer, the smaller the wavelength of the surface acoustic wave generated by the interdigital transducer. In order to match the wavelength of the surface acoustic wave, the number of the fingers of the corresponding reflector should be increased. Since the first finger spacing F1 is greater than the second finger spacing F2, the number of the first fingers 31 and the number of the second fingers 32 are adjusted so as to match the dominant modes of the surface acoustic waves of the two interdigital transducers 20. Thus, the reflection effect of the first reflector 30 on the two interdigital transducers 20 is ensured.

[0148] Since the first finger spacing F1 is greater than the second finger spacing F2, it can be understood that the filter 100 is configured to have a relatively small number of the first fingers 31, so as to reduce the size of the plurality of the first fingers 31 along the first direction 001 under the premise of ensuring the Q value of the filter 100, which is conducive to the miniaturization of the filter 100.

[0149] In one embodiment, the ratio of the number of second finger strips 32, the number of third finger strips 33, and the number of first finger strips 31 is 2:1:1. Based on the first finger spacing F1, the second finger spacing F2, and the third finger spacing F3, the filter 100 of this application adjusts the ratio of the number of first finger strips 31, second finger strips 32, and third finger strips 33 to further improve the Q value of the filter 100 while ensuring the reflection effect of the first reflective grating 30 on the main modes of the two interdigital transducers 20.

[0150] In one embodiment, the sum of the numbers of the first finger strip 31, the second finger strip 32, and the third finger strip 33 is greater than or equal to 10. Since the number of fingers in the reflective grating is positively correlated with the reflective effect of the reflective grating on surface acoustic waves (SAW), the filter 100 of this application ensures that the first finger strip 31 and the second finger strip 32 reflect the SAW generated by the corresponding interdigital transducers 20 during operation, and that the third finger strip 33 blocks the SAW generated by the two interdigital transducers 20 during operation, by controlling the sum of the numbers of the first finger strip 31, the second finger strip 32, and the third finger strip 33 to be greater than 10. This ensures the Q value of the filter 100 of this application.

[0151] In one embodiment, the sum of the number of the first finger strip 31, the second finger strip 32 and the third finger strip 33 is less than or equal to 40, so as to reduce the overall size of the first reflective grating 30, which is beneficial to the miniaturization of the filter 100 of this application.

[0152] In one embodiment, the sum of the number of the first finger strip 31, the second finger strip 32 and the third finger strip 33 is greater than or equal to 10 and less than or equal to 40, so as to reduce the overall size of the first reflective grating 30 while ensuring the Q value of the filter 100 of this application, which is beneficial to the miniaturization of the filter 100 of this application.

[0153] In one embodiment, such as Figure 4 As shown, the filter 100 of this application also includes a second reflective grating 40 and a third reflective grating 50. Along the first direction 001, the first interdigital transducer 20a and the second reflective grating 40 are located on the first side of the first reflective grating 30, and the second interdigital transducer 20b and the third reflective grating 50 are located on the second side of the first reflective grating.

[0154] Along the first direction 001, a first reflective grating 30 and a second reflective grating 40 are respectively provided on opposite sides of the first interdigital transducer 20a. The first reflective grating 30 and the second reflective grating 40 cooperate with each other to constrain the surface acoustic wave generated when the first interdigital transducer 20a is working. Specifically, during the operation of the filter 100 of this application, the main mode of the surface acoustic wave generated when the first interdigital transducer 20a is working will propagate along the first direction 001 to the first reflective grating 30 and the second reflective grating 40 respectively, and the main mode propagating to the first reflective grating 30 will be reflected by multiple first finger strips 31.

[0155] The second reflective grating 40 includes a plurality of fourth fingers 41, and the main mode propagating to the second reflective grating 40 is reflected towards the first interdigital transducer 20a under the action of the plurality of fourth fingers 41. Thus, the constraint on the main mode generated by the first interdigital transducer 20a is realized, and the Q value of the first interdigital transducer 20a is improved.

[0156] Along the first direction 001, the opposite sides of the second interdigital transducer 20b are respectively provided with the first reflective grating 30 and the third reflective grating 50. The first reflective grating 30 and the third reflective grating 50 cooperate to realize the constraint on the surface acoustic wave generated by the second interdigital transducer 20b during operation. Specifically, during the operation of the filter 100 of the present application, the main mode of the surface acoustic wave generated by the second interdigital transducer 20b during operation propagates along the first direction 001 to the first reflective grating 30 and the third reflective grating 50, respectively, and the main mode propagating to the first reflective grating 30 is reflected by the plurality of second fingers 32.

[0157] The third reflective grating 50 includes a plurality of fifth fingers 51, and the surface acoustic wave propagating to the third reflective grating 50 is reflected towards the second interdigital transducer 20b under the action of the plurality of fifth fingers 51. Thus, the constraint on the main mode generated by the second interdigital transducer 20b is realized, and the Q value of the second interdigital transducer 20b is improved.

[0158] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 is greater than or equal to the smaller one of the number of the fourth fingers 41 and the number of the fifth fingers 51.

[0159] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 is less than or equal to the larger one of the number of the fourth fingers 41 and the number of the fifth fingers 51.

[0160] Based on the above two embodiments, by adjusting the size relationship between the total number of the fingers of the first reflective grating 30 and the number of the fourth fingers 41 and the number of the fifth fingers 51, on the one hand, the reflection effect of the first fingers 31 and the second fingers 32 in the first reflective grating 30 on the two interdigital transducers 20 is ensured. On the other hand, the overall size of the first reflective grating 30 is controlled, which facilitates the miniaturization of the filter 100.

[0161] Please refer to Figure 12 for the partial enlarged structural schematic diagram of the filter 100 provided in an embodiment of the present application.

[0162] As Figure 12As shown, along the first direction 001, the distance between the central axes of two adjacent fourth finger strips 41 is the fourth finger distance F4, the distance between the central axes of two adjacent first electrode fingers 22a in the first interdigital transducer 20a is equal to the fourth finger distance F4, and the distance between the central axes of adjacent fourth finger strips 41 and first electrode fingers 22a is equal to the fourth finger distance F4.

[0163] Since the frequency of the main mode of the first interdigital transducer 20a is determined by the finger spacing between two adjacent first electrode fingers 22a within the first interdigital transducer 20a, the filter 100 of this application sets the finger spacing between two adjacent first electrode fingers 22a, the distance between the central axis of the adjacent fourth finger strip 41 and the first electrode finger 22a, and the finger spacing between two adjacent fourth finger strips 41 as a fourth finger spacing F4, thereby ensuring that multiple fourth finger strips 41 can reflect the main mode of the first interdigital transducer 20a.

[0164] Please refer to the above. Figure 13 The diagram shown is a partial enlarged view of another embodiment of the filter 100 provided in this application.

[0165] like Figure 13 As shown, along the first direction 001, the distance between the central axes of two adjacent fifth finger strips 51 is the fifth finger distance F5, the distance between the central axes of two adjacent second electrode fingers 22b in the second interdigital transducer 20b is equal to the fifth finger distance F5, and the distance between the central axes of adjacent fifth finger strips 51 and second electrode fingers 22b is equal to the fifth finger distance F5.

[0166] Since the frequency of the dominant mode of the second interdigital transducer 20b is determined by the finger spacing between two adjacent second electrode fingers 22b within the second interdigital transducer 20b, the filter 100 of this application ensures that multiple fifth finger strips 51 can reflect the dominant mode of the second interdigital transducer 20b by setting the finger spacing between two adjacent second electrode fingers 22b, the distance between the central axis of an adjacent fifth finger strip 51 and the second electrode finger 22b, and the finger spacing between two adjacent fifth finger strips 51 as a fifth finger spacing F5.

[0167] In one embodiment, please refer back. Figure 5 Along the arrangement direction of the two busbars 21, the distance between the ends of any two adjacent electrode fingers 22 in each interdigital transducer 20 that are not connected to the busbar 21 is the aperture size L, and the aperture size L of the two interdigital transducers 20 is equal.

[0168] In one embodiment, the spacing between the two busbars 21 of each interdigital transducer 20 is equal, and the length of the first finger bar 31, the length of the second finger bar 32, and the length of the third finger bar 33 are all equal to the spacing between the two busbars 21 of any interdigital transducer 20.

[0169] The length of each finger of the first reflective grating 30 is set equal to the distance between the two bus bars 21 along the arrangement direction of the two bus bars 21 to define the length of each finger in the first reflective grating 30, facilitating the miniaturization of the filter 100. Meanwhile, the length of each finger in the first reflective grating 30 is matched with the interdigital transducer 20a to ensure the reflection effect of the first reflective grating 30 on the surface acoustic wave.

[0170] The filter 100 provided in the application includes a piezoelectric substrate 10, an interdigital transducer 20 and a first reflective grating 30. The number of the interdigital transducers 20 is multiple, and the multiple interdigital transducers 20 and the first reflective grating 30 are arranged on the surface of the piezoelectric substrate 10 along the planar direction of the piezoelectric substrate 10.

[0171] For example, please refer to Figure 14 and Figure 15 , wherein Figure 14 is another structural schematic diagram of the filter 100 provided in an embodiment of the application. Figure 15 is a schematic diagram of the arrangement structure of the filter 100 provided in an embodiment of the application.

[0172] As shown in Figure 14 and Figure 15 , the number of the interdigital transducers 20 is two, and the two interdigital transducers 20 are arranged on the opposite sides of the first reflective grating 30. Each interdigital transducer 20 includes two bus bars 21 arranged in parallel and at intervals, and multiple electrode fingers 22 arranged in parallel and at intervals. One of the two bus bars 21 is used to receive an external signal, and the other of the two bus bars 21 is used to output a signal. The multiple electrode fingers 22 are located between the two bus bars 21. Part of the multiple electrode fingers 22 are connected with one bus bar 21, and the other part of the multiple electrode fingers 22 are connected with the other bus bar 21.

[0173] For convenience of description, the bus bar 21 used to receive an external signal is defined as a first bus bar 21a, and the bus bar 21 used to output a signal is defined as a second bus bar 21b. The electrode finger 22 connected with the first bus bar 21a is defined as a first electrode 221, and the electrode finger 22 connected with the second bus bar 21b is defined as a second electrode 222.

[0174] Specifically, the first electrode 221 and the second electrode 222 are arranged alternately along a first direction 001. The first electrode 221 and the second electrode 222 both extend along a second direction 002. Specifically, as shown in Figure 15As shown, along the first direction 001, there is one second electrode 222 between any two adjacent first electrodes 221, and there is one first electrode 221 between any two adjacent second electrodes 222.

[0175] The first bus bar 21a and the second bus bar 21b both extend along the first direction 001, wherein the second direction 002 intersects the first direction 001. For example, the second direction 002 can be perpendicular to the first direction 001, so that the angle between each electrode finger 22 and the bus bar connected thereto is 90°. Alternatively, the second direction 002 can not be perpendicular to the first direction 001, so that the angle between each electrode finger 22 and the bus bar connected thereto is greater than 90°.

[0176] In the embodiment of the present application, when an external excitation signal is applied to the first bus bar 21a of the interdigital transducer 20, each first electrode 221 converts the electrical signal into a surface acoustic wave, which propagates along the surface of the piezoelectric substrate 10 and is converted into an electrical signal by each second electrode 222, and then output by the second bus bar 21b.

[0177] The surface acoustic wave is used to implement the frequency selection function and signal processing function of the filter 100. During the propagation of the surface acoustic wave, the main propagation direction of the surface acoustic wave is the first direction 001. However, in actual processes, due to edge effects and acoustic wave diffraction effects, the propagation direction of the surface acoustic wave formed on the surface of the piezoelectric substrate 10 can also be other directions. In one embodiment, the surface acoustic wave propagating in the other directions is absorbed by an acoustic absorption material (not shown in the figure). In one embodiment, the first direction 001 is the arrangement direction of the two interdigital transducers 20.

[0178] In the embodiment of the present application, along the first direction 001, the first reflective grating 30 is located on one side of the interdigital transducer 20. When the surface acoustic wave generated by the interdigital transducer 20 propagates along the first direction 001, it will be transmitted into the first reflective grating 30. The first reflective grating 30 is used to reflect the surface acoustic wave propagating into the first reflective grating 30, so as to confine the surface acoustic wave in the interdigital transducer 20 generating the surface acoustic wave.

[0179] Since the first reflective grating 30 is located between the two interdigital transducers 20, it can be understood that the first reflective grating 30 can simultaneously reflect the surface acoustic waves generated by the two interdigital transducers 20, and confine the propagation range of the surface acoustic waves generated by the two interdigital transducers 20, thereby improving the performance of the two interdigital transducers. In turn, the working performance of the filter of the present application is improved.

[0180] Meanwhile, compared with the scheme that each interdigital transducer independently adopts a pair of same reflective gratings and different interdigital transducers adopt different reflective gratings in the related art, the filter 100 utilizes one first reflective grating 30 to constrain the surface acoustic waves generated by the two interdigital transducers 20 when working, which is also conducive to reducing the spacing between the two interdigital transducers 20 and facilitating the miniaturization of the filter 100.

[0181] Please see the partial top view structural schematic diagram of the filter 100 provided in an embodiment of the application shown in Figure 16

[0182] As shown in Figure 15 and Figure 16 , the first reflective grating 30 includes a first finger 31, a second finger 32 and a third finger 33. Along the first direction 001, the first finger 31 and the second finger 32 are arranged on the two sides of the third finger 33. In the embodiment of the application, one of the two interdigital transducers 20 is located on one side of the third finger 33 with the first finger 31, and the other of the two interdigital transducers 20 is located on the other side of the third finger 33 with the second finger 32.

[0183] Among them, for the convenience of description, the interdigital transducer 20 on the same side of the first finger 31 is defined as the first interdigital transducer 20a. The interdigital transducer 20 on the same side of the second finger 32 is defined as the second interdigital transducer 20b.

[0184] As shown in Figure 15 and Figure 16 , the surface acoustic wave generated by the first interdigital transducer 20a when working will propagate towards the first finger 31. Among them, when the main mode of the surface acoustic wave is transmitted to the first finger 31, the first finger 31 is used to reflect the main mode. Thus, the main mode in the surface acoustic wave generated by the first interdigital transducer 20a when working is constrained in the first interdigital transducer 20a.

[0185] The surface acoustic wave generated by the second interdigital transducer 20b when working will propagate towards the second finger 32. Among them, when the main mode of the surface acoustic wave is transmitted to the second finger 32, the second finger 32 is used to reflect the main mode. Thus, the main mode in the surface acoustic wave generated by the second interdigital transducer 20b when working is constrained in the second interdigital transducer 20b.

[0186] In an embodiment, the number of the first fingers 31 is less than the number of the second fingers 32, and the number of the first fingers 31 is greater than or equal to the number of the third fingers 33. Among them, the third finger 33 is used to block the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 when working.

[0187] ​The first reflective grating 30 has a relatively large number of first fingers 31 and second fingers 32, which can ensure the reflection effect of the first reflective grating 30 on the two interdigital transducers 20. The third fingers 33 with a small number are arranged, which can block the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 during operation on the basis of ensuring the overall size of the first reflective grating 30, thereby improving the Q value of the filter 100.

[0188] In an embodiment, the number of the first fingers 31 and the second fingers 32 is multiple, and the finger spacing between the adjacent two first fingers 31 is greater than the finger spacing between the adjacent two second fingers 32, so as to respectively match different main modes of the interdigital transducers 20, so that the first reflective grating 30 can simultaneously realize the reflection of the surface acoustic waves of the two interdigital transducers 20 with different main modes. Thereby, the operating range of the filter 100 is improved.

[0189] In an embodiment, the ratio of the number of the second fingers 32, the number of the third fingers 33, and the number of the first fingers 31 is 2:1:1. The filter 100 adjusts the number ratio of the first fingers 31, the second fingers 32, and the third fingers 33 based on the finger spacing between the adjacent two first fingers 31 and the finger spacing between the adjacent two second fingers 32, so as to further improve the Q value of the filter 100 on the premise of ensuring the reflection effect of the first reflective grating 30 on the main modes of the two interdigital transducers 20.

[0190] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32, and the third fingers 33 is greater than or equal to 10. Since the number of fingers of the reflective grating is positively correlated with the reflection effect of the reflective grating on the surface acoustic wave, the filter 100 controls the sum of the number of the first fingers 31, the second fingers 32, and the third fingers 33, so as to ensure the reflection effect of the first fingers 31 and the second fingers 32 on the surface acoustic waves generated by the corresponding interdigital transducers 20 during operation, and the blocking effect of the third fingers 33 on the surface acoustic waves generated by the two interdigital transducers 20 during operation. Thereby, the Q value of the filter 100 is ensured.

[0191] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32, and the third fingers 33 is less than or equal to 40, so as to reduce the overall size of the first reflective grating 30, which is conducive to the miniaturization of the filter 100.

[0192] In an embodiment, the first IDT 20a includes a plurality of first electrode fingers 22a, and the second IDT 20b includes a plurality of second electrode fingers 22b; wherein the finger pitch of the first IDT 20a is a first finger pitch F1, and the distance between the first finger strip 31 adjacent to the first IDT 20a and the central axis of the adjacent first electrode finger 22a is equal to the first finger pitch F1; the finger pitch of the second IDT 20b is a second finger pitch F2, and the distance between the second finger strip 32 adjacent to the second IDT 20b and the central axis of the adjacent second electrode finger 22b is equal to the second finger pitch F2, and the first finger pitch F1 is greater than the second finger pitch F2.

[0193] Since the main mode frequency of the first IDT 20a is determined by the finger pitch of the two adjacent first electrode fingers 22a within the first IDT 20a. The filter 100 of the present application sets the finger pitch of the two adjacent first electrode fingers 22a and the distance between the first finger strip 31 adjacent to the first IDT 20a and the central axis of the adjacent first electrode finger 22a as the first finger pitch F1, so as to ensure that the plurality of first finger strips 31 can reflect the main mode of the first IDT 20a.

[0194] Since the main mode frequency of the second IDT 20b is determined by the finger pitch of the two adjacent second electrode fingers 22b within the second IDT 20b. The filter 100 of the present application sets the finger pitch of the two adjacent second electrode fingers 22b and the distance between the second finger strip 32 adjacent to the second IDT 20b and the central axis of the adjacent second electrode finger 22b as the second finger pitch F2, so as to ensure that the plurality of second finger strips 32 can reflect the main mode of the second IDT 20b.

[0195] In an embodiment, the filter 100 of the present application further includes a second reflection grating 40 and a third reflection grating 50, and along the first direction 001, the first IDT 20a and the second reflection grating 40 are located on the first side of the first reflection grating 30, and the second IDT 20b and the third reflection grating 50 are located on the second side of the first reflection grating.

[0196] Along the first direction 001, the first reflection grating 30 and the second reflection grating 40 are respectively arranged on the opposite sides of the first IDT 20a. The first reflection grating 30 and the second reflection grating 40 cooperate to confine the surface acoustic wave generated by the first IDT 20a during operation. Specifically, during the operation of the filter 100 of the present application, the main mode of the surface acoustic wave generated by the first IDT 20a during operation will propagate along the first direction 001 to the first reflection grating 30 and the second reflection grating 40, respectively, and the main mode propagating to the first reflection grating 30 will be reflected by the plurality of first finger strips 31.

[0197] The second reflective grating 40 includes a plurality of fourth fingers 41, and the main mode propagating to the second reflective grating 40 is reflected towards the first interdigital transducer 20a under the action of the plurality of fourth fingers 41. Thus, the constraint on the main mode generated by the first interdigital transducer 20a is realized, and the Q value of the first interdigital transducer 20a is improved.

[0198] Along the first direction 001, the opposite sides of the second interdigital transducer 20b are respectively provided with the first reflective grating 30 and the third reflective grating 50. The first reflective grating 30 and the third reflective grating 50 cooperate with each other to realize the constraint on the surface acoustic wave generated by the second interdigital transducer 20b during operation. Specifically, during the operation of the filter 100, the main mode of the surface acoustic wave generated by the second interdigital transducer 20b propagates along the first direction 001 to the first reflective grating 30 and the third reflective grating 50 respectively, and the main mode propagating to the first reflective grating 30 is reflected by the plurality of second fingers 32.

[0199] The third reflective grating 50 includes a plurality of fifth fingers 51, and the surface acoustic wave propagating to the third reflective grating 50 is reflected towards the second interdigital transducer 20b under the action of the plurality of fifth fingers 51. Thus, the constraint on the main mode generated by the second interdigital transducer 20b is realized, and the Q value of the second interdigital transducer 20b is improved.

[0200] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 is greater than or equal to the smaller one of the number of the fourth fingers 41 and the number of the fifth fingers 51.

[0201] In an embodiment, the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 is less than or equal to the larger one of the number of the fourth fingers 41 and the number of the fifth fingers 51.

[0202] Based on the above two embodiments, by adjusting the size relationship between the total number of the fingers of the first reflective grating 30 and the number of the fourth fingers 41 and the number of the fifth fingers 51, on the one hand, the reflection effect of the first fingers 31 and the second fingers 32 in the first reflective grating 30 on the two interdigital transducers 20 is ensured. On the other hand, the overall size of the first reflective grating 30 is controlled, which facilitates the miniaturization of the filter 100.

[0203] In an embodiment, along the first direction 001, the distance between the center axes of two adjacent fourth fingers 41 is a fourth finger distance F4, the distance between the center axes of two adjacent first electrode fingers 22a in the first interdigital transducer 20a is equal to the fourth finger distance F4, and the distance between the center axes of an adjacent fourth finger 41 and a first electrode finger 22a is equal to the fourth finger distance F4.

[0204] Since the frequency of the main mode of the first IDT 20a is determined by the finger spacing of the two adjacent first electrode fingers 22a in the first IDT 20a. The filter 100 of the present application sets the finger spacing of the two adjacent first electrode fingers 22a, the spacing between the center axis of the adjacent fourth finger 41 and the first electrode finger 22a, and the finger spacing of the two adjacent fourth fingers 41 to the fourth finger spacing F4, so as to ensure that the plurality of fourth fingers 41 can reflect the main mode of the first IDT 20a.

[0205] In an embodiment, along the first direction 001, the spacing between the center axes of the two adjacent fifth fingers 51 is the fifth finger spacing F5, the spacing between the center axes of the two adjacent second electrode fingers 22b in the second IDT 20b is equal to the fifth finger spacing F5, and the spacing between the center axes of the adjacent fifth finger 51 and the second electrode finger 22b is equal to the fifth finger spacing F5.

[0206] Since the frequency of the main mode of the second IDT 20b is determined by the finger spacing of the two adjacent second electrode fingers 22b in the second IDT 20b. The filter 100 of the present application sets the finger spacing of the two adjacent second electrode fingers 22b, the spacing between the center axis of the adjacent fifth finger 51 and the second electrode finger 22b, and the finger spacing of the two adjacent fifth fingers 51 to the fifth finger spacing F5, so as to ensure that the plurality of fifth fingers 51 can reflect the main mode of the second IDT 20b.

[0207] Based on the above-mentioned embodiments, specifically, admittance can be used to describe the response process of the element to the signal, in the filter 100 of the present application, conductance is used to measure the loss of the acoustic wave propagating on the surface of the piezoelectric substrate 10, and Q value is used to describe the signal quality in the filter 100.

[0208] Figures 17-22 The comparison chart of the conductance curves obtained based on different surface acoustic wave frequencies in the filter 100 of the present application, the comparative example and the filter in Reference Example 1. Among them, Figures 17-22 the abscissa is frequency, unit: MHz, and the ordinate is conductance, unit: dB. Figures 23-28 The comparison chart of the Q values obtained based on different surface acoustic wave frequencies in the filter 100 of the present application, the comparative example and the filter in Reference Example 1. Among them, Figures 23-28 the abscissa is frequency, unit: MHz, and the ordinate is Q value.

[0209] For each of the embodiments, each of the comparative examples, and reference example 1, the filter includes two interdigital transducers, which are a first interdigital transducer and a second interdigital transducer. For the first interdigital transducer, the interdigital transducer has an interdigital pitch of 2.8 μm, a duty cycle of 0.42, an aperture size of 140 μm, 131 electrode fingers, an electrode finger material of aluminum, a piezoelectric substrate material of LiTaO3, and an electrode finger thickness of 410 nm.

[0210] For the second interdigital transducer, the interdigital transducer has an interdigital pitch of 2.5 μm, a duty cycle of 0.42, an aperture size of 140 μm, 131 electrode fingers, an electrode finger material of aluminum, a piezoelectric substrate material of LiTaO3, and an electrode finger thickness of 410 nm.

[0211] Each of the comparative examples includes three reflective gratings, which are spaced apart from each other, and each of the interdigital transducers is located between two adjacent reflective gratings. Each of the reflective gratings has 20 fingers.

[0212] The number of the comparative examples is three, which are comparative example 1 to comparative example 3. The number of the fingers of the reflective gratings allocated to the first interdigital transducer and the second interdigital transducer is different in each of the comparative examples. In each of the comparative examples, the number of the first fingers, the distance between two adjacent first fingers, the distance between the first finger and the electrode finger of the first interdigital transducer, and the interdigital pitch of the first interdigital transducer are equal. In this case, the number of the first fingers is equal to the number of the fingers of the reflective gratings allocated to the first interdigital transducer. Similarly, the number of the second fingers, the distance between two adjacent second fingers, the distance between the second finger and the electrode finger of the second interdigital transducer, and the interdigital pitch of the second interdigital transducer are equal. In this case, the number of the second fingers is equal to the number of the fingers of the reflective gratings allocated to the second interdigital transducer. Therefore, the number of the fingers of the reflective gratings allocated to the first interdigital transducer and the second interdigital transducer is different in each of the comparative examples, which means that the ratio of the number of the fingers of the reflective gratings allocated to the first interdigital transducer to the number of the fingers of the reflective gratings allocated to the second interdigital transducer is different in each of the comparative examples, i.e., the ratio of the number of the first fingers to the number of the second fingers is different in each of the comparative examples.

[0213] Specifically, the ratio of the number of the first fingers to the number of the second fingers is 5:15 in comparative example 1. The ratio of the number of the first fingers to the number of the second fingers is 15:5 in comparative example 2. The ratio of the number of the first fingers to the number of the second fingers is 10:10 in comparative example 3.

[0214] The first reflective grating 30, the second reflective grating 40 and the third reflective grating 50 each include 20 finger strips based on the structure of the two above-mentioned interdigital transducers 20. The number of embodiments is 3, which are respectively embodiment 1-embodiment 3. The number of the first finger strips 31, the second finger strips 32 and the third finger strips 33 in the first reflective grating 30 in each embodiment is different. The third finger spacing F3 is 2.915 μm.

[0215] Specifically, the number of the first finger strips 31, the second finger strips 32 and the third finger strips 33 in embodiment 1 is 5:5:10. The number of the first finger strips 31, the second finger strips 32 and the third finger strips 33 in embodiment 2 is 10:5:5. The number of the first finger strips 31, the second finger strips 32 and the third finger strips 33 in embodiment 3 is 6:5:9.

[0216] Reference example 1 includes four reflective gratings based on the structure of the two above-mentioned interdigital transducers. One reflective grating is arranged on each of the opposite sides of each interdigital transducer, and the two interdigital transducers are spaced apart. Each reflective grating includes 20 finger strips.

[0217] Based on the above-mentioned three comparative examples, three embodiments and one reference example 1, the conductance curve graphs and the Q value curve graphs are respectively simulated to form Figures 17-28 the legends shown in the figures. Each legend includes the conductance curve or the Q value curve corresponding to the first interdigital transducer represented by a solid line, and the conductance curve or the Q value curve corresponding to the second interdigital transducer represented by a dashed line. It can be understood that the conductance curve corresponding to the reference example 1 is consistent in the legend of Figures 17-22 , and the Q value curve corresponding to the reference example 1 is also consistent in the legend of Figures 23-28 .

[0218] Specifically, Figures 17-19 are the conductance curve comparison graphs of the two interdigital transducers in comparative example 1-comparative example 3 and reference example 1. Figures 20-22 are the conductance curve comparison graphs of the two interdigital transducers in embodiment 1-embodiment 3 and reference example 1. Figures 23-25 are the Q value curve comparison graphs of the two interdigital transducers in comparative example 1-comparative example 3 and reference example 1. Figures 26-28 are the Q value curve comparison graphs of the two interdigital transducers in embodiment 1-embodiment 3 and reference example 1.

[0219] As shown in Figures 17-19 , and Figures 23-25 , the more the number of finger strips allocated to any one of the interdigital transducers in comparative example 1-comparative example 3, the better the consistency of the conductance curve or the Q value curve corresponding to the interdigital transducer with the conductance curve or the Q value curve corresponding to the reference example 1.

[0220] contrast Figures 17-28 It can be seen that the conductivity curves and Q-value curves corresponding to Examples 1-3 are more consistent with those of Reference Example 1 than those of Comparative Examples 1-3. For example, a comparison is made using the conductivity curves of Comparative Example 1 and Example 1. Since Example 1 has the largest number of second finger strips 32, the comparison... Figure 20 and Figure 17 It can be seen that the conductivity curve corresponding to the second interdigital transducer 20b in Example 1 is in good agreement with the conductivity curve corresponding to the reference example 1, while the conductivity curve corresponding to the first interdigital transducer 20a in Example 1 is significantly better in agreement with the reference example 1 than that of Comparative Example 1.

[0221] Similarly, referring to the above figures, it is clear that the conductivity curve obtained in Example 2 is in better agreement with that in Comparative Example 2 than with that in Comparative Example 1. The Q-value curves obtained in Examples 1 and 2 are also in better agreement with those in Comparative Examples 1 and 2 than with those in Comparative Examples 1 and 2.

[0222] This is because Embodiments 1 and 2 of this application provide a third finger strip 33, which blocks the mutual influence of surface acoustic waves generated by the two interdigital transducers 20 during operation, thereby improving the performance of the filter 100 and increasing the Q value of the filter 100.

[0223] In Comparative Examples 1-3, the conductivity curve and Q-value curve corresponding to Comparative Example 3 show good consistency with those corresponding to Reference Example 1. In the embodiments of this application, the number of second fingers 32 is greater than or equal to the number of third fingers 33, and less than or equal to the number of first fingers 31, which corresponds to the conductivity curve and Q-value curve corresponding to Example 3.

[0224] By comparison Figure 19 and Figure 22 ,as well as Figure 25 and Figure 28 It can be seen that the conductivity curve and Q value curve corresponding to Example 3 are more consistent with those of Reference Example 1 than those of Comparative Example 3. This is because Example 3 of this application provides a third finger strip 33 and adjusts the quantitative relationship between the third finger strip 33 and the first finger strip 31 and the second finger strip 32, so as to make full use of the third finger strip 33 to block the mutual influence of the surface acoustic waves generated when the two interdigital transducers 20 are working, thereby improving the performance of the filter 100 of this application and improving the Q value of the filter 100 of this application.

[0225] It is worth mentioning that the finger distribution ratio schemes proposed in the above-mentioned Comparative Examples 1-3 and Examples 1-3 of the present application will not affect the resonant frequency, electromechanical coupling coefficient, static capacitance and other characteristics of the filter. Therefore, the consistency differences in the above-mentioned Figures 17-28 illustrated in the legends will not come from the resonant frequency, electromechanical coupling coefficient, static capacitance and other characteristics of the filter.

[0226] Specifically, Figure 29 is a comparison chart of the admittance curves of Comparative Examples 1-3 and Reference Example 1. Figure 30 is a comparison chart of the admittance curves of Examples 1-3 and Reference Example 1. Among them, Figure 29 and Figure 30 The abscissa is frequency, unit: MHz, and the ordinate is admittance, unit: dB. Figure 29 and Figure 30 In the above-mentioned Comparative Examples 1-3 and Examples 1-3, the admittance curve corresponding to the first interdigital transducer is represented by a solid line, and the admittance curve corresponding to the second interdigital transducer is represented by a dashed line. In order to facilitate the comparison of the curve consistency of each comparative example or example and reference example 1, the ordinate of the admittance curve corresponding to each comparative example and each example is processed. In the illustration, the curves of each comparative example and each example are all shifted along the ordinate. Specifically, Figure 29 In the above-mentioned Comparative Examples 1-3 and Examples 1-3, the admittance curve corresponding to the first interdigital transducer is represented by a solid line, and the admittance curve corresponding to the second interdigital transducer is represented by a dashed line. In order to facilitate the comparison of the curve consistency of each comparative example or example and reference example 1, the ordinate of the admittance curve corresponding to each comparative example and each example is processed. In the illustration, the curves of each comparative example and each example are all shifted along the ordinate. Specifically, Figure 30 In the above-mentioned Comparative Examples 1-3 and Examples 1-3, the admittance curve corresponding to the first interdigital transducer is represented by a solid line, and the admittance curve corresponding to the second interdigital transducer is represented by a dashed line. In order to facilitate the comparison of the curve consistency of each comparative example or example and reference example 1, the ordinate of the admittance curve corresponding to each comparative example and each example is processed. In the illustration, the curves of each comparative example and each example are all shifted along the ordinate. Specifically,

[0227] As can be seen from Figure 29 and Figure 30 , the admittance curves of each comparative example and each example are consistent with the admittance curve of reference example 1. Correspondingly, the finger distribution ratio schemes proposed in the above-mentioned Comparative Examples 1-3 and Examples 1-3 of the present application will not affect the resonant frequency, electromechanical coupling coefficient, static capacitance and other characteristics of the filter.

[0228] In order to further prove the viewpoint of the present application, Figures 31-37 is a comparison chart of the conductance curves of the filters in the present application, comparative examples and reference example 2 based on different surface acoustic wave frequencies. Among them, Figures 31-37 The abscissa is frequency, unit: MHz, and the ordinate is conductance, unit: dB. Figures 38-44 is a comparison chart of the Q values of the filters in the present application, comparative examples and reference example 2 based on different surface acoustic wave frequencies. Figures 38-44 The abscissa is frequency, unit: MHz, and the ordinate is Q value.

[0229] The comparative examples have three groups, which are Comparative Example 4-Comparative Example 6. The examples have four groups, which are Example 4-Example 7. The filters of Comparative Example 4-Comparative Example 6 and Example 4-Example 7 each include two interdigital transducers, which are a first interdigital transducer and a second interdigital transducer. For the first interdigital transducer, the finger spacing of the adjacent two electrode fingers is 2.8 μm, the duty cycle of the electrode fingers is 0.42, the aperture size is 140 μm, the number of electrode fingers is 131, the electrode finger material is aluminum, the piezoelectric substrate material is LiTaO3, and the thickness of the electrode fingers is 410 nm.

[0230] For the second interdigital transducer, the finger spacing of the adjacent two electrode fingers is 2.5 μm, the duty cycle of the electrode fingers is 0.42, the aperture size is 140 μm, the number of electrode fingers is 131, the electrode finger material is aluminum, the piezoelectric substrate material is LiTaO3, and the thickness of the electrode fingers is 410 nm.

[0231] Each comparative example includes three reflective gratings based on the structure of the two interdigital transducers described above, and the three reflective gratings are arranged at intervals, with each interdigital transducer being located between two adjacent reflective gratings. The number of finger strips of the reflective grating located on the side of the first interdigital transducer away from the second interdigital transducer is 30, the number of finger strips of the reflective grating located on the side of the second interdigital transducer away from the first interdigital transducer is 20, and the number of finger strips of the reflective grating located between the first interdigital transducer and the second interdigital transducer is 25.

[0232] The number of finger strips of the reflective gratings between the two interdigital transducers in each comparative example is different. The number of finger strips of the common reflective gratings is different. As described above, each finger strip of the common reflective gratings is a first finger strip or a second finger strip.

[0233] Specifically, the number of first finger strips and the number of second finger strips in Comparative Example 4 are in a ratio of 8:17. The number of first finger strips and the number of second finger strips in Comparative Example 5 are in a ratio of 17:8. The number of first finger strips and the number of second finger strips in Comparative Example 6 are in a ratio of 12:13.

[0234] Each example includes 30 finger strips in the first reflective grating 30, 20 finger strips in the second reflective grating 40, and 25 finger strips in the third reflective grating 50 based on the structure of the two interdigital transducers 20 described above. The number of first finger strips 31, the number of second finger strips 32, and the number of third finger strips 33 in the first reflective grating 30 in each example are different. The third finger spacing F3 is equal to 2.915 μm.

[0235] Specifically, the number allocation ratio of the first finger strip 31, the third finger strip 33 and the second finger strip 32 in Example 4 is 8:5:12. The number allocation ratio of the first finger strip 31, the third finger strip 33 and the second finger strip 32 in Example 5 is 15:2:8. The number allocation ratio of the first finger strip 31, the third finger strip 33 and the second finger strip 32 in Example 6 is 12:5:8. The number allocation ratio of the first finger strip 31, the third finger strip 33 and the second finger strip 32 in Example 7 is 8:4:13.

[0236] Reference Example 2 is based on the structure of the above two interdigital transducers. Reference Example 2 includes four reflection gratings, one reflection grating is arranged on the opposite side of each interdigital transducer, and the two interdigital transducers are spaced apart. The number of finger strips of the two reflection gratings on the opposite sides of the first interdigital transducer is 30, and the number of finger strips of the two reflection gratings on the opposite sides of the second interdigital transducer is 20.

[0237] Based on the above three comparative examples, four examples and one reference example 2, the conductance curve and the Q value curve are simulated respectively, and the conductance curve and the Q value curve are formed respectively as shown in the legends. Figures 31-44 In each legend, the conductance curve or the Q value curve corresponding to the first interdigital transducer is represented by a solid line, and the conductance curve or the Q value curve corresponding to the second interdigital transducer is represented by a dashed line. It can be understood that in the legends, Figures 31-44 the conductance curve or the Q value curve corresponding to reference example 2 remains unchanged.

[0238] Specifically, Figures 31-33 are respectively the conductance curve comparison diagrams of the two interdigital transducers in Comparative Example 4-Comparative Example 6 and reference example 2. Figures 34-37 are respectively the conductance curve comparison diagrams of the two interdigital transducers in Example 4-Example 7 and reference example 2. Figures 38-40 are respectively the Q value curve comparison diagrams of the two interdigital transducers in Comparative Example 4-Comparative Example 6 and reference example 2. Figures 41-44 are respectively the Q value curve comparison diagrams of the two interdigital transducers in Example 4-Example 7 and reference example 2.

[0239] By comparing the above legends, it is obvious that the consistency of the conductance curve and the Q value curve obtained by Example 4-Example 7 compared with Comparative Example 4-Comparative Example 6 and reference example 2 is good. This is because the third finger strip 33 is arranged in the present application Example 4-Example 7, which blocks the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 when working, thereby improving the use performance of the filter 100 of the present application and improving the Q value of the filter 100 of the present application.

[0240] It is to be understood that the terms "first", "second", and the like, do not imply or mean any relative importance or imply the number of indicated technical features. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of embodiments of the present application, the meaning of "a plurality" is two or more, unless otherwise specifically limited.

[0241] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" means that the specific feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0242] It should be understood that the application of the present application is not limited to the above examples, and those of ordinary skill in the art can make improvements or changes according to the above description, and all such improvements and changes shall fall within the scope of the claims of the present application. Those of ordinary skill in the art can understand that all or part of the processes of the above embodiments are implemented, and equivalent changes made in accordance with the claims of the present application, still fall within the scope of the present application.

Claims

1. A filter, characterized by, The piezoelectric substrate, and a first reflective grating and two interdigital transducers arranged on the surface of the piezoelectric substrate, the two interdigital transducers are arranged on opposite sides of the first reflective grating; The first reflective grating comprises a first finger, a second finger and a third finger connected, the first finger and the second finger are arranged on both sides of the third finger along the first direction; wherein, The distance between the third finger adjacent to the first finger and the center axis of the adjacent first finger is the first distance, the distance between the third finger adjacent to the second finger and the center axis of the adjacent second finger is the second distance, the first distance and the second distance are not equal; The number of the first finger and the second finger is multiple, the number of the third finger is one, multiple first fingers, the third finger, multiple second fingers are arranged in the first direction, the distance between the center axes of two adjacent first fingers is the first finger distance, the distance between the center axes of two adjacent second fingers is the second finger distance; define the difference between 2 times of the first distance and the first finger distance as the third finger distance; and / or, define the difference between 2 times of the second distance and the second finger distance as the third finger distance; wherein, the third finger distance is greater than the first finger distance and the second finger distance; or, The number of the first finger, the second finger and the third finger is multiple, multiple first fingers, multiple third fingers, multiple second fingers are arranged in the first direction; the distance between the center axes of two adjacent first fingers is the first finger distance, the distance between the center axes of two adjacent second fingers is the second finger distance, the distance between the center axes of two adjacent third fingers is the third finger distance, the third finger distance is greater than the first finger distance and the second finger distance; the first distance is equal to half of the sum of the third finger distance and the first finger distance; the second distance is equal to half of the sum of the third finger distance and the second finger distance.

2. The filter of claim 1, wherein, The difference between 2 times of the first distance and the first finger distance is equal to the difference between 2 times of the second distance and the second finger distance.

3. The filter according to claim 1 or 2, characterized in that, The width of the third finger is greater than the width of the first finger, and the width of the third finger is greater than the width of the second finger; and / or, In the first direction, the gap size between two adjacent first fingers is the first gap size, the gap size between two adjacent second fingers is the second gap size, the gap size between the third finger adjacent to the first finger and the adjacent first finger is greater than the first gap size, and the gap size between the third finger adjacent to the second finger and the adjacent second finger is greater than the second gap size.

4. The filter according to claim 1 or 2, characterized in that, The ratio of the third finger distance to the first finger distance is greater than or equal to 1.

01.

5. The filter according to claim 1 or 2, characterized in that, The third finger distance is less than or equal to 1.04 times the first finger distance.

6. The filter according to claim 1 or 2, characterized in that, The third finger distance is less than or equal to 1.1 times the first finger distance.

7. The filter according to claim 1 or 2, characterized in that, The two interdigital transducers comprise a first interdigital transducer and a second interdigital transducer, along the first direction, the first interdigital transducer and the first finger strip are located at a first side of the third finger strip, the second interdigital transducer and the second finger strip are located at a second side of the third finger strip, the first interdigital transducer comprises a plurality of first electrode fingers, and the second interdigital transducer comprises a plurality of second electrode fingers; wherein, The finger spacing of the first interdigital transducer is equal to a first finger spacing, and the spacing between the first finger strip adjacent to the first interdigital transducer and the central axis of the adjacent first electrode finger is equal to the first finger spacing; The finger spacing of the second interdigital transducer is equal to a second finger spacing, and the spacing between the second finger strip adjacent to the second interdigital transducer and the central axis of the adjacent second electrode finger is equal to the second finger spacing, and the first finger spacing is greater than the second finger spacing.

8. The filter according to claim 1 or 2, characterized in that, The number of the first finger strips is a plurality, the number of the second finger strips is a plurality, and the number of the first finger strips and the number of the second finger strips are both greater than or equal to the number of the third finger strips.

9. The filter of claim 8, wherein, The number of the first finger strips is less than or equal to the number of the second finger strips.

10. The filter according to claim 1 or 2, characterized in that, The ratio of the number of the second finger strips, the number of the third finger strips, and the number of the first finger strips is 2:1:

1.

11. The filter according to claim 1 or 2, characterized in that, The sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is greater than or equal to 10.

12. The filter according to claim 1 or 2, characterized in that, The sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is less than or equal to 40.

13. The filter according to claim 1 or 2, characterized in that, The first direction is the arrangement direction of the two interdigital transducers.

14. The filter of claim 1 or 2, wherein, The finger spacing of the two interdigital transducers is not equal.

15. The filter of claim 1 or 2, wherein, The filter further comprises a second reflective grid and a third reflective grid, the two interdigital transducers comprise a first interdigital transducer and a second interdigital transducer, along the first direction, the first interdigital transducer and the second reflective grid are located at a first side of the first reflective grid, and the second interdigital transducer and the third reflective grid are located at a second side of the first reflective grid; The second reflective grid comprises a plurality of fourth finger strips, and the third reflective grid comprises a plurality of fifth finger strips; The sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is greater than or equal to the smaller one of the number of the fourth finger strips and the number of the fifth finger strips; And / or, the sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is less than or equal to the larger one of the number of the fourth finger strips and the number of the fifth finger strips.

16. The filter of claim 15, wherein, Along the first direction, the spacing between the central axes of two adjacent fourth finger strips is a fourth finger spacing, the spacing between the central axes of two adjacent electrode fingers in the first interdigital transducer is equal to the fourth finger spacing, and the spacing between the central axes of the adjacent fourth finger strip and the electrode finger is equal to the fourth finger spacing; Along the first direction, the spacing between the central axes of two adjacent fifth finger strips is a fifth finger spacing, the spacing between the central axes of two adjacent electrode fingers in the second interdigital transducer is equal to the fifth finger spacing, and the spacing between the central axes of the adjacent fifth finger strip and the electrode finger is equal to the fifth finger spacing.

17. The filter of claim 1 or 2, wherein, Each of the interdigital transducers comprises two bus bars arranged in parallel and spaced apart, and a plurality of electrode fingers located between the two bus bars, part of the electrode fingers being connected to one of the bus bars, another part of the electrode fingers being connected to the other bus bar, and the electrode fingers connected to different bus bars being arranged alternately; The distance between the end portions of any two adjacent electrode fingers in each of the interdigital transducers which are not connected to the bus bars along the arrangement direction of the two bus bars is an aperture size, and the aperture sizes of the two interdigital transducers are equal.

18. The filter of claim 17, wherein, The distance between the two bus bars of each of the interdigital transducers is equal, and the length size of the first finger strip, the length size of the second finger strip, and the length size of the third finger strip are all equal to the distance between the two bus bars of any one of the interdigital transducers.

19. A filter, characterized by The first reflective grating is used for reflecting the surface acoustic wave propagating to the first reflective grating. The first reflective grating comprises first finger strips, second finger strips, and third finger strips connected in series, the first finger strips and the second finger strips being arranged on the two sides of the third finger strips along a first direction; wherein the number of the first finger strips is less than the number of the second finger strips, and the number of the first finger strips is greater than or equal to the number of the third finger strips. The distance between a third finger strip adjacent to the first finger strip and the central axis of the adjacent first finger strip is a first distance, the distance between a third finger strip adjacent to the second finger strip and the central axis of the adjacent second finger strip is a second distance, and the first distance and the second distance are not equal. The number of the first finger strips and the number of the second finger strips are plural, the distance between the central axes of two adjacent first finger strips is a first finger distance, and the distance between the central axes of two adjacent second finger strips is a second finger distance; the first finger distance and the second finger distance are both less than a third finger distance. When the number of the third finger strips is one, the third finger distance is defined as the difference between twice the first distance and the first finger distance; and / or, the third finger distance is defined as the difference between twice the second distance and the second finger distance. When the number of the third finger strips is plural, the distance between the central axes of two adjacent third finger strips is the third finger distance, the first distance is equal to half of the sum of the third finger distance and the first finger distance, and the second distance is equal to half of the sum of the third finger distance and the second finger distance.

20. The filter of claim 19, wherein, The finger distance between two adjacent first finger strips is greater than the finger distance between two adjacent second finger strips.

21. The filter of claim 19, wherein, The ratio of the number of the second finger strips, the number of the third finger strips, and the number of the first finger strips is 2:1:

1.

22. The filter of claim 19, wherein, The sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is greater than or equal to 10.

23. The filter of claim 19, wherein, The sum of the number of the first finger strips, the number of the second finger strips, and the number of the third finger strips is less than or equal to 40.

24. The filter of any one of claims 19-23, wherein, The two interdigital transducers comprise a first interdigital transducer and a second interdigital transducer, along the first direction, the first interdigital transducer and the first finger are located at a first side of the third finger, the second interdigital transducer and the second finger are located at a second side of the third finger, the first interdigital transducer comprises a plurality of first electrode fingers, and the second interdigital transducer comprises a plurality of second electrode fingers; wherein, The finger spacing of the first interdigital transducer is a first finger spacing, and the spacing between the first finger adjacent to the first interdigital transducer and the central axis of the adjacent first electrode finger is equal to the first finger spacing; The finger spacing of the second interdigital transducer is a second finger spacing, and the spacing between the second finger adjacent to the second interdigital transducer and the central axis of the adjacent second electrode finger is equal to the second finger spacing, and the first finger spacing is greater than the second finger spacing.

25. The filter of any one of claims 19-23, wherein, The filter further comprises a second reflective grid and a third reflective grid, the two interdigital transducers comprise a first interdigital transducer and a second interdigital transducer, along the first direction, the first interdigital transducer and the second reflective grid are located at a first side of the first reflective grid, and the second interdigital transducer and the third reflective grid are located at a second side of the first reflective grid; The second reflective grid comprises a plurality of fourth fingers, and the third reflective grid comprises a plurality of fifth fingers; The sum of the number of the first finger, the second finger and the third finger is greater than or equal to the smaller one of the number of the fourth finger and the number of the fifth finger; and / or, the sum of the number of the first finger, the second finger and the third finger is less than or equal to the larger one of the number of the fourth finger and the number of the fifth finger. Along the first direction, the spacing between the central axes of two adjacent fourth fingers is a fourth finger spacing, the spacing between the central axes of two adjacent electrode fingers in the first interdigital transducer is equal to the fourth finger spacing, and the spacing between the central axes of the adjacent fourth finger and the electrode finger is equal to the fourth finger spacing; 26. The filter of claim 25, wherein, Along the first direction, the spacing between the central axes of two adjacent fifth fingers is a fifth finger spacing, the spacing between the central axes of two adjacent electrode fingers in the second interdigital transducer is equal to the fifth finger spacing, and the spacing between the central axes of the adjacent fifth finger and the electrode finger is equal to the fifth finger spacing. The filter comprises the filter according to any one of claims 1-26.

27. A radio frequency front end module, comprising: The radio frequency front end module comprises the radio frequency front end module according to claim 27.

28. An electronic device, comprising: ​

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