Filter, radio frequency front-end module and electronic equipment

Abstract

The invention relates to a filter, a radio frequency front-end module and electronic equipment, the filter comprises a piezoelectric substrate, a first reflecting grating and two interdigital transducers, the first reflecting grating and the two interdigital transducers are arranged on the surface of the piezoelectric substrate, and the two interdigital transducers are respectively arranged on two opposite sides of the first reflecting grating; the first reflecting grating comprises a first finger strip, a second finger strip and a third finger strip which are connected, and the first finger strip and the second finger strip are arranged on the two sides of the third finger strip in the first direction; wherein the distance between the central axis of the 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 the central axis of the 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 is not equal to the second distance. According to the filter disclosed by the invention, the first interval is unequal to the second interval by adjusting the intervals among the first finger strip, the second finger strip and the third finger strip in the first reflecting grating shared by the two interdigital transducers, so that the Q value of the filter disclosed by the invention is improved.

Description

Technical Field

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

[0002] In the field of radio frequency, filters are usually composed of a piezoelectric substrate and multiple interdigital transducers. The mutual conversion of electrical signals and acoustic signals is achieved through the cooperation of each interdigital transducer and the piezoelectric substrate. In order to constrain the surface acoustic waves generated by the interdigital transducer during operation, a reflection grating is set on the opposite sides of each interdigital transducer to form a resonator.

[0003] In the related art, in order to achieve miniaturization of the filter, two resonators usually share a reflection grating. When the parameters of the two resonators are different, the shared reflection grating will cause the main modes of the two resonators to affect each other, thereby causing the quality factor (Q value) of the filter to deteriorate. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a solution to improve the Q value of the filter, which specifically includes the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a filter, comprising a piezoelectric substrate, and a first reflection grating and two interdigital transducers disposed on a surface of the piezoelectric substrate, wherein the two interdigital transducers are arranged on opposite sides of the first reflection grating;

[0006] The first reflective grid includes a first finger, a second finger and a third finger connected to each other, wherein the first finger and the second finger are arranged on both sides of the third finger along a first direction; wherein,

[0007] The distance between a third finger adjacent to the first finger and the central axis of the adjacent first finger is a first distance, and the distance between a 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.

[0008] The filter of the present application arranges two IDTs on opposite sides of a first reflection grating so that the first reflection grating can simultaneously constrain the propagation range of surface acoustic waves generated by the two IDTs when they are working, thereby improving the performance of the two IDTs while facilitating the miniaturization of the filter of the present application.

[0009] The filter of the present application also adjusts the finger spacings of the first finger, the second finger, and the third finger in the first reflection grid so that the first spacing between adjacent first fingers and third fingers is not equal to the second spacing between adjacent second fingers and third fingers, thereby avoiding the mutual influence of the surface acoustic waves generated when the two interdigital transducers are working and improving the Q value of the filter of the present application.

[0010] In the second aspect, an embodiment of the present application provides a filter, comprising a piezoelectric substrate, and 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 a first finger, a second finger and a third finger connected to each other, the first finger and the second finger are arranged on both sides of the third finger along a first direction; wherein the number of the first fingers is less than the number of the second fingers, and the number of the first fingers is greater than or equal to the number of the third fingers.

[0011] The filter provided in the present application is able to improve the Q value of the filter of the present application by arranging a relatively small number of third fingers between multiple first fingers and multiple second fingers, so as to ensure the overall size of the first reflection grating and utilize the third fingers to block the mutual influence of surface acoustic waves generated when two interdigital transducers are working, thereby improving the Q value of the filter of the present application.

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

[0013] In a fourth aspect, an embodiment of the present application provides an electronic device, including a radio frequency front-end module.

[0014] It is understandable that the RF front-end module provided in the third aspect of the present application and the electronic device provided in the fourth aspect adopt the surface acoustic wave device provided in the first and second aspects of the present application. The RF front-end module and the electronic device of the present application also have a better Q value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of an electronic device provided in one embodiment of the present application;

[0016] Figure 2 This is a schematic diagram of the structure of a radio frequency front-end module provided in one embodiment of the present application;

[0017] Figure 3 A schematic diagram of the structure of a filter provided in one embodiment of the present application;

[0018] Figure 4 A schematic diagram of a top view of a filter provided in an embodiment of the present application;

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

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

[0021] Figure 7 Another partial structural diagram of a filter provided in one embodiment of the present application;

[0022] Figure 8 This is another schematic top view of the structure of a filter provided in one embodiment of the present application;

[0023] Fig. 9 It is another partial structural schematic diagram of a filter provided in an embodiment of the present application;

[0024] Fig.10 This is another partial structural diagram of a filter provided in an embodiment of the present application;

[0025] Fig.11 This is another partial structural diagram of a filter provided in an embodiment of the present application;

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

[0027] Fig.13 Another partially enlarged structural schematic diagram of a filter provided in an embodiment of the present application;

[0028] Fig.14 Another structural schematic diagram of a filter provided in an embodiment of the present application;

[0029] Fig.15 A schematic diagram of the arrangement structure of a filter provided in an embodiment of the present application;

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

[0031] Fig.17 It is a comparison diagram of the conductivity curves of Comparative Example 1 and Reference Example 1 in the related art;

[0032] Fig.18 It is a comparison diagram of the conductivity curves of Comparative Example 2 and Reference Example 1 in the related art;

[0033] Fig.19 It is a comparison diagram of the conductivity curves of Comparative Example 3 and Reference Example 1 in the related art;

[0034] Fig. 20A comparison diagram of the conductivity curves of Example 1 and Reference Example 1 provided in one embodiment of the present application;

[0035] Fig.21 A comparison diagram of the conductivity curves of Example 2 and Reference Example 1 provided in one embodiment of the present application;

[0036] Fig. 22 A comparison diagram of the conductivity curves of Example 3 and Reference Example 1 provided in one embodiment of the present application;

[0037] Fig.23 It is a comparison diagram of Q value curves of Comparative Example 1 and Reference Example 1 in the related art;

[0038] Fig.24 It is a comparison diagram of Q value curves of Comparative Example 2 and Reference Example 1 in the related art;

[0039] Fig.25 It is a comparison diagram of Q value curves of Comparative Example 3 and Reference Example 1 in the related art;

[0040] Fig.26 A comparison diagram of Q value curves of Example 1 and Reference Example 1 provided in one embodiment of the present application;

[0041] Fig. 27 A comparison diagram of Q value curves of Example 2 and Reference Example 1 provided in one embodiment of the present application;

[0042] Fig.28 A comparison diagram of Q value curves of Example 3 and Reference Example 1 provided in one embodiment of the present application;

[0043] Fig.29 It is a comparison diagram of the admittance curves of Comparative Examples 1 to Comparative Examples 3 and Reference Example 1 in the related art;

[0044] Fig.30 A comparison diagram of the admittance curves of Examples 1 to 3 and Reference Example 1 provided in one embodiment of the present application;

[0045] Fig.31 It is a comparison diagram of the conductivity curves of Comparative Example 4 and Reference Example 2 in the related art;

[0046] Fig.32 It is a comparison diagram of the conductivity curves of Comparative Example 5 and Reference Example 2 in the related art;

[0047] Fig.33 It is a comparison diagram of the conductivity curves of Comparative Example 6 and Reference Example 2 in the related art;

[0048] Fig.34 A comparison diagram of the conductivity curves of Example 4 and Reference Example 2 provided in one embodiment of the present application;

[0049] Fig.35 A comparison diagram of the conductivity curves of Example 5 and Reference Example 2 provided in one embodiment of the present application;

[0050] Fig.36 A comparison diagram of the conductivity curves of Example 6 and Reference Example 2 provided in one embodiment of the present application;

[0051] Fig.37 A comparison diagram of the conductivity curves of Example 7 and Reference Example 2 provided in one embodiment of the present application;

[0052] Fig.38 It is a comparison diagram of Q value curves of Comparative Example 4 and Reference Example 2 in the related art;

[0053] Fig.39 It is a comparison diagram of Q value curves of Comparative Example 5 and Reference Example 2 in the related art;

[0054] Fig.40 It is a comparison diagram of Q value curves of Comparative Example 6 and Reference Example 2 in the related art;

[0055] Fig.41 A comparison diagram of Q value curves of Example 4 and Reference Example 2 provided in one embodiment of the present application;

[0056] Fig.42 A comparison diagram of Q value curves of Example 5 and Reference Example 2 provided in one embodiment of the present application;

[0057] Fig.43 A comparison diagram of Q value curves of Example 6 and Reference Example 2 provided in one embodiment of the present application;

[0058] Fig.44 This is a comparison chart of Q value curves of Example 7 and Reference Example 2 provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given 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 thoroughly and comprehensively understood.

[0060] The following descriptions of the embodiments are with reference to the attached diagrams to illustrate specific embodiments that the present application can be used to implement. The serial numbers for the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in the present application, unless otherwise specified, include direct and indirect connections (couplings). The directional terms mentioned in the present application, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", "side", etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0061] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrally connected; it can be mechanically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances. It should be noted that the terms "first", "second", etc. in the specification, claims, and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include", "may include", "include", or "may include" used in this application indicate the existence of the corresponding functions, operations, elements, etc. disclosed, and do not limit one or more other functions, operations, elements, etc. In addition, the terms "include" or "include" indicate 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 inclusions.

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

[0063] See also Figure 1 The structure diagram of the electronic device 300 provided in one embodiment of the present application is shown.

[0064] like Figure 1As shown, the electronic device 300 of the present application includes a transceiver, an antenna and a RF front-end module 200. The RF front-end module is connected between the transceiver and the antenna, and is used to power amplify the RF signal output by the transceiver to obtain a sufficiently large RF output power, and transmit the power-amplified RF signal to the antenna to be radiated through the antenna; and / or, is used to amplify the weaker RF signal received by the antenna with a lower noise coefficient and transmit it to the transceiver.

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

[0066] See also Figure 2 The structure diagram of the RF front-end module 200 provided in one embodiment of the present application is shown.

[0067] The RF front-end module is a component that integrates one or more discrete devices such as RF switches, low-noise amplifiers, filters, duplexers, power amplifiers, etc. into an independent module, thereby improving integration and hardware performance and miniaturizing the size.

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

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

[0070] The number of the amplifier 203 may be one or more. Optionally, the amplifier 203 may 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 filters 100 may also be one or more. When there are multiple filters 100, different filters 100 may be used to filter signals on different signal transmission paths, wherein the different signal transmission paths may be a transmission path and a receiving path of the same frequency band, or a transmission path and a receiving path of different frequency bands, or a transmission path of different frequency bands, or a receiving path of different frequency bands.

[0072] The switch 202 may include a plurality of switch paths therein, and a common end of the plurality of switch paths is connected to the signal end 201 , so as to switch filters on different signal transmission paths to be connected to the signal end 201 .

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

[0074] When the amplifier 203 is a power amplifier, the filter 100 is used to receive the RF signal amplified by the amplifier 203 , filter the received RF signal, and then transmit the filtered RF signal to the signal end 201 through the closed switch 202 .

[0075] In one embodiment, the RF 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 duplexer or a multiplexer. That is, the RF front-end module 200 also includes a multiplexer, and the multiplexer includes a plurality of filters 100 .

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

[0077] In one embodiment, the filter 100 of the present application includes a piezoelectric substrate 10, an IDT 20, and a first reflection grating 30. There are multiple IDTs 20, and the multiple IDTs 20 and the first reflection grating 30 are arranged at intervals on the surface of the piezoelectric substrate 10. Specifically, there are at least two IDTs 20, and at least two IDTs 20 are arranged on opposite sides of the first reflection grating 30.

[0078] For example, see Figure 3 and Figure 4 ,in Figure 3 1 is a schematic diagram of the structure of a filter 100 provided in an embodiment of the present application. Figure 4 FIG. 1 is a schematic diagram of a top view of a filter 100 provided in an embodiment of the present application.

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

[0080] For the convenience of description, in the present embodiment and subsequent embodiments, description is made with respect to two adjacent interdigital transducers 20 disposed on the surface of the piezoelectric substrate 10 .

[0081] Please see Figure 5 FIG. 1 is a schematic diagram of a partial structure of a filter 100 provided in an embodiment of the present application.

[0082] like Figure 5 As shown, 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. Among them, one bus bar 21 of the two bus bars 21 is used to receive external signals, and the other bus bar 21 of the two bus bars 21 is used to output signals. 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 another part of the plurality of electrode fingers 22 are connected to the other bus bar 21.

[0083] For ease of description, the bus bar 21 for receiving external signals is defined as the first bus bar 21a, and the bus bar 21 for outputting signals is defined as the second bus bar 21b. The electrode fingers 22 connected to the first bus bar 21a are defined as the first electrodes 221, and the electrode fingers 22 connected to the second bus bar 21b are defined as the second electrodes 222.

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

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

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

[0087] Among them, the surface acoustic wave is used to realize the frequency selection function and signal processing function of the filter 100 of the present application. During the propagation of the surface acoustic wave, the main propagation direction of the surface acoustic wave is the first direction 001. However, in the actual process, due to the effects such as edge effect and acoustic wave diffraction, the propagation direction of the surface acoustic wave formed on the surface of the piezoelectric substrate 10 may also be other directions. In one embodiment, the surface acoustic wave propagating in the other directions will be 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 film-on-insulator surface acoustic wave filters (POI SAW filters), conventional surface acoustic wave filters (NSAW filters), temperature compensated surface acoustic wave filters (TCSAW filters), and filter devices formed by interconnecting them through a certain topology, including devices including interdigital transducers, and the present application does not limit this.

[0089] In one embodiment, the first direction 001 is the arrangement direction of the two IDTs 20 .

[0090] In the embodiment of the present application, along the first direction 001, the first reflection grating 30 is located at one side of the IDT 20. When the surface acoustic wave generated by the IDT 20 is in operation and propagates along the first direction 001, it is transmitted to the first reflection grating 30. The first reflection grating 30 is used to reflect the surface acoustic wave propagating to the first reflection grating 30, so as to confine the surface acoustic wave within the IDT 20 that generates the surface acoustic wave.

[0091] Since the first reflection grating 30 is located between the two IDTs 20, it is understandable that the first reflection grating 30 can simultaneously reflect the surface acoustic waves generated by the two IDTs 20 when they are working, restricting the propagation range of the surface acoustic waves generated by the two IDTs 20 when they are working, thereby improving the performance of the two IDTs, and further improving the working performance of the filter of the present application.

[0092] At the same time, compared with the solution in the related art that each interdigital transducer independently adopts a pair of the same reflection gratings for reflection and different interdigital transducers adopt different reflection gratings, the filter 100 of the present application utilizes a first reflection grating 30 to constrain the surface acoustic waves generated when the two interdigital transducers 20 are working, which is also beneficial to reducing the distance between the two interdigital transducers 20, and is beneficial to the miniaturization of the filter 100 of the present application.

[0093] Please see Figure 6 and Figure 7 ,in Figure 6 FIG. 1 is another schematic top view of the structure of the filter 100 provided in one embodiment of the present application. Figure 7 FIG. 1 is another partial structural diagram of a filter 100 provided in an embodiment of the present application.

[0094] like Figure 6 and Figure 7 As shown, 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 both sides of the third finger 33. In the embodiment of the present application, one of the two IDTs 20 and the first finger 31 are located on one side of the third finger 33, and the other of the two IDTs 20 and the second finger 32 are located on the other side of the third finger 33.

[0095] For the convenience of description, the IDT 20 on the same side as the first finger 31 is defined as the first IDT 20a, and the IDT 20 on the same side as the second finger 32 is defined as the second IDT 20b.

[0096] like Figure 6 and Figure 7 As shown, the surface acoustic wave generated by the first IDT 20a when in operation will propagate toward the first fingers 31. When the main mode of the surface acoustic wave is transmitted to the first fingers 31, the first fingers 31 are used to reflect the main mode. Thus, the main mode of the surface acoustic wave generated by the first IDT 20a when in operation is confined within the first IDT 20a.

[0097] The surface acoustic wave generated by the second IDT 20b when in operation will propagate toward the second fingers 32. When the main mode of the surface acoustic wave is transmitted to the second fingers 32, the second fingers 32 are used to reflect the main mode. Thus, the main mode of the surface acoustic wave generated by the second IDT 20b when in operation is confined within the second IDT 20b.

[0098] In one embodiment, the spacing between a third finger 33 adjacent to the first finger 31 and the central axis of the adjacent first finger 31 is a first spacing D1, and the spacing between a third finger 33 adjacent to the second finger 32 and the central axis of the adjacent second finger 32 is a second spacing D2, and the first spacing D1 is not equal to the second spacing 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. A third finger 33 adjacent to the first finger 31 and an adjacent first finger 31 refer to a third finger 33 closest to the first finger 31 among the third fingers 33 and a first finger 31 closest to the third finger 33 among the first fingers 31, and for convenience, they are also referred to as "adjacent third fingers 33 and first fingers 31" hereinafter. Similarly, a third finger 33 adjacent to the second finger 32 and an adjacent second finger 32 refer to a third finger 33 closest to the second finger 32 among the third fingers 33 and a second finger 32 closest to the third finger 33 among the second fingers 32, and for convenience, they are also referred to as "adjacent third fingers 33 and second fingers 32" hereinafter.

[0100] Since the wavelength range of the surface acoustic wave reflected by the reflection grating is related to the spacing between the central axes of 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 that matches the spacing between the central axes of two adjacent fingers, while part of the non-matching surface acoustic wave will be blocked by the fingers, and the other part will directly pass through the reflection grating and propagate outward, and gradually attenuate with the increase of propagation distance.

[0101] In the embodiment of the present application, the first fingers 31 are configured to match the main mode of the first IDT 20 a , and the second fingers 32 are configured to match the main mode of the second IDT 20 b .

[0102] It is worth pointing out that the main mode described in the embodiment of the present application and subsequent embodiments refers to a portion of the surface acoustic wave that matches the main mode frequency.

[0103] exist Figure 6 and Figure 7 In the illustrated example, the number of the first finger 31, the second finger 32 and the third finger 33 are all one. Correspondingly, a third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 are the adjacent third finger 33 and the first finger 31, and a third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 are the adjacent third finger 33 and the second finger 32.

[0104] In the embodiment of the present application, when the first IDT 20a is working, the first fingers 31 of the first reflective grating 30 can reflect the main mode of the surface acoustic wave generated by the first IDT 20a into the first IDT 20a.

[0105] In the embodiment of the present application, by setting the first spacing D1 and the second spacing D2 to be unequal, the main modes not reflected by the first finger 31 and the second finger 32 can be avoided from influencing each other, 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.

[0106] Similarly, when the second IDT 20b is working, the filter 100 of the present application sets the first spacing D1 and the second spacing D2 to be unequal, which is also conducive to ensuring the performance of the second IDT 20b, 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 plural, in the description of adjacent first fingers 31 and third fingers 33, the third finger 33 refers to a third finger 33 adjacent to the first finger 31, and the first finger 31 refers to the first finger 31 that has the smallest spacing 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 third finger 33, the third finger 33 refers to a third finger 33 adjacent to the second finger 32, and the second finger 32 refers to the second finger 32 that has the smallest spacing from the third finger 33, that is, the second finger 32 adjacent to the third finger 33.

[0109] Please see Figure 8 and Fig. 9 ,in Figure 8 FIG. 1 is another schematic top view of the structure of the filter 100 provided in one embodiment of the present application. Fig. 9 FIG. 1 is another partial structural diagram of a filter 100 provided in an embodiment of the present application.

[0110] like Figure 8 and Fig. 9 As shown, there are multiple first fingers 31 and second fingers 32 , and one third finger 33 . The multiple first fingers 31 , the third fingers 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 multiple first fingers 31 can increase the reflection efficiency of the first fingers 31 to the surface acoustic waves generated 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 multiple second fingers 32 can also increase the reflection efficiency of the second fingers 32 to the surface acoustic waves generated 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. In this way, the Q value of the filter 100 of the present application is improved.

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

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

[0114] That is, there is a relatively large spacing between the third finger 33 and the first finger 31 and the second finger 32. On the one hand, the main mode that is not reflected by the first finger 31 will gradually attenuate before propagating to the third finger 33, thereby reducing the mutual influence of the main modes of the two IDTs 20. On the other hand, the relatively large spacing also makes it difficult for the part of the main mode generated by the two IDTs 20 that passes through the first finger 31 and the second finger 32 to pass through the third finger 33 to the IDT 20 on the other side, so that the third finger 33 can block the mutual influence of the surface acoustic waves when the two IDTs 20 are working. This improves the Q value of the filter 100 of the present application.

[0115] In one embodiment, the difference between twice the first spacing D1 and the first finger spacing F1 is equal to the difference between twice the second spacing D2 and the second finger spacing F2.

[0116] Please see Fig.10 FIG. 1 is another partial structural diagram of a filter 100 provided in an embodiment of the present application.

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

[0118] Along the first direction 001, a plurality of first fingers 31 are arranged equidistantly, a plurality of second fingers 32 are arranged equidistantly, and a plurality of third fingers 33 are arranged equidistantly. The first finger spacing F1 corresponding to the plurality of first fingers 31 arranged equidistantly is usually set to match the main mode of the first interdigital transducer 20a. That is, the main mode of the surface acoustic wave generated when the first interdigital transducer 20a is working will be reflected by the plurality of first fingers 31, thereby improving the Q value of the first interdigital transducer 20a.

[0119] The second finger spacing F2 corresponding to the multiple equally spaced second fingers 32 is usually set to match the main mode of the second IDT 20b. That is, part of the surface acoustic waves that match the main mode frequency among the surface acoustic waves generated by the second IDT 20b when it is working 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 equal intervals increase the spacing between the first fingers 31 and the second fingers 32, reducing 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 being propagated to the IDT 20 on the other side when it is working. Thereby, the Q value of the filter of the present application is improved.

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

[0122] For a surface acoustic wave, when the surface acoustic wave propagates on the surface of the piezoelectric substrate 10, the surface acoustic wave will gradually decay as the propagation time increases without the effect of other structures. Usually, during the decay process, the intensity of the surface acoustic wave will gradually decrease. In the embodiment of the present application, when the main mode of the surface acoustic wave generated by the interdigital transducer 20 propagates between the first finger 31 and the third finger 33, and between the second finger 32 and the third finger 33, the intensity of the main mode will gradually decrease.

[0123] It can be understood that the larger the first spacing D1 and the second spacing D2, the lower the intensity of the main mode when propagating to the third finger 33, and correspondingly, the smaller the mutual influence between the main modes of the two IDTs 20. The larger the first spacing D1 and the second spacing D2, the larger the size of the first reflection grating 30, and the larger the spacing between the first IDT 20a and the second IDT 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 sizes of the first spacing D1 and the second spacing D2, so as to improve the Q value of the filter 100 of the present application while facilitating the miniaturization of the filter 100 of the present application.

[0125] In one embodiment, the width of the third finger 33 is greater than the width of the second finger 32. That is, the first reflection grating 30 of the filter 100 of the present application adjusts the size relationship between the third finger spacing F3 and the second finger spacing F2 by adjusting the width of the third finger 33. This ensures that the third finger 33 blocks the surface acoustic wave generated by the second interdigital transducer 20b when it is working, and improves the Q value of the filter 100 of the present application.

[0126] In one embodiment, the width of the third finger 33 is greater than the width of the first finger 31. That is, the first reflection grating 30 of the filter 100 of the present application adjusts the size relationship between the third finger spacing F3 and the first finger spacing F1 by adjusting the width of the third finger 33. This ensures that the third finger 33 blocks the surface acoustic wave generated when the first interdigital transducer 20a is working, thereby improving the Q value of the filter 100 of the present application.

[0127] Please see Fig.11 FIG. 1 is another partial structural diagram of a filter 100 provided in an embodiment of the present application.

[0128] like Fig.11 As shown, along the first direction 001 , the gap size between two adjacent first fingers 31 is the first gap size G1 , and the gap size between a third finger 33 adjacent to a first finger 31 and the adjacent first finger 31 is greater than the first gap size G1 .

[0129] That is, the first reflection grating 30 of the filter 100 of the present application adjusts the size relationship between the third finger spacing F3 and the first finger spacing F1 by adjusting the adjacent third fingers 33 and the first fingers 31. This ensures that the third fingers 33 block the surface acoustic waves generated by the first interdigital transducer 20a when working, and improves the Q value of the filter 100 of the present application.

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

[0131] That is, the first reflective grating 30 of the filter 100 of the present application adjusts the size relationship between the third finger spacing F3 and the second finger spacing F2 by adjusting the gap size between the adjacent third fingers 33 and the second fingers 32. This ensures that the third fingers 33 block the surface acoustic waves generated by the second interdigital transducer 20b when working, and improves the Q value of the filter 100 of the present application.

[0132] In one 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. Along the first direction 001, the gap size between a third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is greater than the first gap size G1, and the gap size between a 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 one embodiment, the width of the third finger 33, the width of the first finger 31, and the width of the second finger 32 are all equal. Along the first direction 001, the gap size between a third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is greater than the first gap size G1, and the gap size between a 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 one 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. Along the first direction 001, the gap dimension between a third finger 33 adjacent to the first finger 31 and the adjacent first finger 31 is equal to the first gap dimension G1, and the gap dimension between a third finger 33 adjacent to the second finger 32 and the adjacent second finger 32 is equal to the second gap dimension G2.

[0135] In one 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 so that the intensity of the main mode propagating to the third finger strip 33 is relatively weak, thereby reducing the mutual influence of the main modes of the two interdigital transducers 20 and improving the Q value of the filter 100 of the present application.

[0136] At the same time, 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 33 on the main modes of the two interdigital transducers 20. This avoids the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 when working, and improves the Q value of the filter 100 of the present application.

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

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

[0139] In one embodiment, please refer to Figure 4 and Figure 5 The first IDT 20a includes a plurality of first electrode fingers 22a, the finger pitch of the first IDT 20a is equal to the first finger pitch F1, and the spacing between the first finger 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.

[0140] Since the frequency of the main mode of the first IDT 20a is determined by the finger spacing between two adjacent first electrode fingers 22a in the first IDT 20a, the filter 100 of the present application sets the finger spacing between two adjacent first electrode fingers 22a and the spacing between the first finger 31 adjacent to the first IDT 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 fingers 31 can achieve reflection of the main mode of the first IDT 20a.

[0141] In one embodiment, if Figure 4 and Figure 5 As shown, the second IDT 20b includes a plurality of second electrode fingers 22b, the finger pitch of the second IDT 20b is equal to the second finger pitch F2, and the spacing between the central axis of the second finger 32 adjacent to the second IDT 20b and the adjacent second electrode finger 22b is equal to the second finger pitch F2.

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

[0143] In one embodiment, the finger spacings of the two IDTs 20 are not equal. Exemplarily, in one embodiment, the first finger spacing F1 is greater than the second finger spacing F2. That is, the first reflection grating 30 of the present application can simultaneously realize the reflection of the surface acoustic waves of the two IDTs 20 with different main modes. Thereby, the working range of the filter 100 of the present application is improved.

[0144] In one embodiment, there are multiple first fingers 31 , and there are multiple second fingers 32 . 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 first fingers 31 are used to reflect the main mode of the surface acoustic wave generated when the first IDT 20a is in operation, and the plurality of second fingers 32 are used to reflect the main mode of the surface acoustic wave generated when the second IDT 30b is in operation.

[0146] Since the more fingers of the reflection grating, the better the reflection effect of the reflection grating on the corresponding surface acoustic wave. In the embodiment of the present application, the filter 100 of the present application is provided with a relatively large number of first fingers 31 and second fingers 32, so as to improve the reflection effect of the first reflection grating 30 on the surface acoustic wave generated when the first interdigital transducer 20a and the second interdigital transducer 30b are working, thereby ensuring the performance of the filter 100 of the present application.

[0147] In one embodiment, the number of the first fingers 31 is less than or equal to the number of the second fingers 32. Since the smaller the interdigital spacing of the IDT, the smaller the wavelength of the surface acoustic wave generated when it is working, the finger spacing of the corresponding reflection grating should be increased accordingly to match the wavelength of the surface acoustic wave. Since the first finger spacing F1 is greater than the second finger spacing F2, the relationship between the number of the first fingers 31 and the second fingers 32 is adjusted so that the first fingers 31 and the second fingers 32 match the main mode of the surface acoustic wave of the corresponding two IDTs 20. In this way, the reflection effect of the first reflection grating 30 on the two IDTs 20 is ensured.

[0148] Since the first finger spacing F1 is greater than the second finger spacing F2, it is understandable that the relatively small number of first fingers 31 can reduce the size of the first fingers 31 along the first direction 001 while ensuring the Q value of the filter 100 of the present application, which is conducive to the miniaturization of the filter 100 of the present application.

[0149] In one 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 of the present application adjusts the ratio of the number of the first fingers 31, the second fingers 32, and the third fingers 33 based on the first finger spacing F1, the second finger spacing F2, and the third finger spacing F3, so as to further improve the Q value of the filter 100 of the present application while ensuring the reflection effect of the first reflection grating 30 on the main modes of the two interdigital transducers 20.

[0150] In one 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 reflection grating is positively correlated with the reflection effect of the reflection grating on the surface acoustic wave. The filter 100 of the present application controls the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 to be greater than 10 to ensure the reflection effect of the first fingers 31 and the second fingers 32 on the surface acoustic wave generated when the corresponding interdigital transducers 20 are working, and the blocking effect of the third fingers 33 on the surface acoustic wave generated when the two interdigital transducers 20 are working. In this way, the Q value of the filter 100 of the present application is guaranteed.

[0151] In one embodiment, the sum of the numbers 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 beneficial to the miniaturization of the filter 100 of the present application.

[0152] In one 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 and less than or equal to 40, so as to reduce the overall size of the first reflection grating 30 while ensuring the Q value of the filter 100 of the present application, which is conducive to the miniaturization of the filter 100 of the present application.

[0153] In one embodiment, if Figure 4 As shown, the filter 100 of the present application further includes a second reflection grating 40 and a third reflection grating 50. Along the first direction 001, the first IDT 20a and the second reflection grating 40 are located on a first side of the first reflection grating 30, and the second IDT 20b and the third reflection grating 50 are located on a second side of the first reflection grating.

[0154] Along the first direction 001, the first reflection grating 30 and the second reflection grating 40 are respectively provided on opposite sides of the first interdigital transducer 20a. The first reflection grating 30 and the second reflection grating 40 cooperate with each other to realize the constraint of the surface acoustic wave generated when the first interdigital transducer 20a is working. Specifically, during the operation of the filter 100 of the present 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 reflection grating 30 and the second reflection grating 40 respectively, and the main mode propagated to the first reflection grating 30 will be reflected by the plurality of first fingers 31.

[0155] The second reflection grating 40 includes a plurality of fourth fingers 41. The main mode propagating to the second reflection grating 40 is reflected toward the first IDT 20a under the action of the plurality of fourth fingers 41. Thus, the main mode generated by the first IDT 20a is constrained, and the Q value of the first IDT 20a is improved.

[0156] Along the first direction 001, the first reflection grating 30 and the third reflection grating 50 are respectively provided on the opposite sides of the second IDT 20b. The first reflection grating 30 and the third reflection grating 50 cooperate with each other to realize the constraint of the surface acoustic wave generated by the second IDT 20b when it is working. Specifically, during the operation of the filter 100 of the present application, the main mode of the surface acoustic wave generated by the second IDT 20b when it is working will propagate along the first direction 001 to the first reflection grating 30 and the third reflection grating 50 respectively, and the main mode propagated to the first reflection grating 30 will be reflected by the plurality of second fingers 32.

[0157] The third reflection grating 50 includes a plurality of fifth fingers 51. The surface acoustic wave propagating to the third reflection grating 50 is reflected toward the second IDT 20b under the action of the plurality of fifth fingers 51. Thus, the main mode generated by the second IDT 20b is constrained, and the Q value of the second IDT 20b is improved.

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

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

[0160] Based on the limitations of the above two embodiments, the filter 100 of the present application adjusts the size relationship between the total number of fingers of the first reflection grating 30 and the number of fourth fingers 41 and the number of fifth fingers 51, so as to ensure the reflection effect of the first fingers 31 and the second fingers 32 in the first reflection grating 30 on the two interdigital transducers 20 on the one hand, and control the overall size of the first reflection grating 30 on the other hand, so as to facilitate the miniaturization of the filter 100.

[0161] Please see Fig.12 FIG. 1 is a schematic diagram of a partially enlarged structure of a filter 100 provided in an embodiment of the present application.

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

[0163] Since the frequency of the main mode of the first IDT 20a is determined by the finger spacing between two adjacent first electrode fingers 22a in the first IDT 20a, the filter 100 of the present application sets the finger spacing between two adjacent first electrode fingers 22a, the spacing between adjacent fourth fingers 41 and the central axis of the first electrode finger 22a, and the finger spacing between two adjacent fourth fingers 41 to the fourth finger spacing F4, so as to ensure that the plurality of fourth fingers 41 can achieve reflection of the main mode of the first IDT 20a.

[0164] Please see Fig.13 Another partially enlarged structural schematic diagram of a filter 100 provided in an embodiment of the present application is shown.

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

[0166] Since the frequency of the main mode of the second IDT 20b is determined by the finger spacing between two adjacent second electrode fingers 22b in the second IDT 20b, the filter 100 of the present application sets the finger spacing between two adjacent second electrode fingers 22b, the spacing between the adjacent fifth fingers 51 and the central axis of the second electrode finger 22b, and the finger spacing between two adjacent fifth fingers 51 to the fifth finger spacing F5, so as to ensure that the plurality of fifth fingers 51 can achieve reflection of the main mode of the second IDT 20b.

[0167] In one embodiment, please refer to Figure 5 Along the arrangement direction of the two bus bars 21 , the distance between the ends of any two adjacent electrode fingers 22 in each IDT 20 that are not connected to the bus bar 21 is the aperture size L, and the aperture sizes L of the two IDTs 20 are equal.

[0168] In one embodiment, the spacing between the two bus bars 21 of each IDT 20 is equal, and the length dimensions of the first finger 31 , the second finger 32 and the third finger 33 are all equal to the spacing between the two bus bars 21 of any IDT 20 .

[0169] Along the arrangement direction of the two bus bars 21, the length of each finger of the first reflective grating 30 is set equal to the spacing between the two bus bars 21 to limit the length of each finger in the first reflective grating 30, which is convenient for miniaturization of the filter 100 of the present application. At the same time, 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 of the present application comprises a piezoelectric substrate 10, an IDT 20 and a first reflective grating 30. There are multiple IDTs 20, and the multiple IDTs 20 and the first reflective grating 30 are arranged on the surface of the piezoelectric substrate 10 at intervals along the plane direction of the piezoelectric substrate 10.

[0171] For example, see Fig.14 and Fig.15 ,in Fig.14 FIG. 1 is another structural schematic diagram of a filter 100 provided in an embodiment of the present application. Fig.15 FIG. 1 is a schematic diagram of the arrangement structure of a filter 100 provided in an embodiment of the present application.

[0172] like Fig.14 and Fig.15 As shown, there are two IDTs 20, and the two IDTs 20 are arranged on opposite sides of the first reflector 30. Each IDT 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. Among them, one bus bar 21 of the two bus bars 21 is used to receive external signals, and the other bus bar 21 of the two bus bars 21 is used to output signals. The plurality of electrode fingers 22 are located between the two bus bars 21. Some of the electrode fingers 22 of the plurality of electrode fingers 22 are connected to one bus bar 21, and another part of the electrode fingers 22 of the plurality of electrode fingers 22 are connected to another bus bar 21.

[0173] For ease of description, the bus bar 21 for receiving external signals is defined as the first bus bar 21a, and the bus bar 21 for outputting signals is defined as the second bus bar 21b. The electrode fingers 22 connected to the first bus bar 21a are defined as the first electrodes 221, and the electrode fingers 22 connected to the second bus bar 21b are defined as the second electrodes 222.

[0174] Specifically, the first electrodes 221 and the second electrodes 222 are alternately arranged along the first direction 001. The first electrodes 221 and the second electrodes 222 both extend along the second direction 002. Fig.15As shown, along the first direction 001 , there is a second electrode 222 between any two adjacent first electrodes 221 , and there is a 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. Exemplarily, the second direction 002 and the first direction 001 may be perpendicular to each other, so that each electrode finger 22 and the bus bar connected thereto have an angle of 90°. Exemplarily, the second direction 002 and the first direction 001 may also be non-perpendicular, so that each electrode finger 22 and the bus bar connected thereto have an angle greater than 90°.

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

[0177] Among them, the surface acoustic wave is used to realize the frequency selection function and signal processing function of the filter 100 of the present application. During the propagation of the surface acoustic wave, the main propagation direction of the surface acoustic wave is the first direction 001. However, in the actual process, due to effects such as edge effects and sound wave diffraction, the propagation direction of the surface acoustic wave formed on the surface of the piezoelectric substrate 10 may also be other directions. In one embodiment, the surface acoustic wave propagating in the remaining directions will be absorbed by the sound absorbing 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 reflection grating 30 is located at one side of the IDT 20. When the surface acoustic wave generated by the IDT 20 is in operation and propagates along the first direction 001, it is transmitted to the first reflection grating 30. The first reflection grating 30 is used to reflect the surface acoustic wave propagating to the first reflection grating 30, so as to confine the surface acoustic wave within the IDT 20 that generates the surface acoustic wave.

[0179] Since the first reflection grating 30 is located between the two IDTs 20, it can be understood that the first reflection grating 30 can simultaneously reflect the surface acoustic waves generated by the two IDTs 20 when they are working, thereby restricting the propagation range of the surface acoustic waves generated by the two IDTs 20 when they are working, thereby improving the performance of the two IDTs, and further improving the working performance of the filter of the present application.

[0180] At the same time, compared with the solution in the related art that each interdigital transducer independently adopts a pair of identical reflection gratings and different interdigital transducers adopt different reflection gratings, the filter 100 of the present application utilizes a first reflection grating 30 to constrain the surface acoustic waves generated when the two interdigital transducers 20 are working, which is also beneficial to reducing the distance between the two interdigital transducers 20, and is beneficial to the miniaturization of the filter 100 of the present application.

[0181] Please see Fig.16 FIG. 1 is a schematic diagram of a partial top view of a filter 100 provided in an embodiment of the present application.

[0182] like Fig.15 and Fig.16 As shown, 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 both sides of the third finger 33. In the embodiment of the present application, one of the two IDTs 20 and the first finger 31 are located on one side of the third finger 33, and the other of the two IDTs 20 and the second finger 32 are located on the other side of the third finger 33.

[0183] For the convenience of description, the IDT 20 on the same side as the first finger 31 is defined as the first IDT 20a, and the IDT 20 on the same side as the second finger 32 is defined as the second IDT 20b.

[0184] like Fig.15 and Fig.16 As shown, the surface acoustic wave generated by the first IDT 20a when in operation will propagate toward the first fingers 31. When the main mode of the surface acoustic wave is transmitted to the first fingers 31, the first fingers 31 are used to reflect the main mode. Thus, the main mode of the surface acoustic wave generated by the first IDT 20a when in operation is confined within the first IDT 20a.

[0185] The surface acoustic wave generated by the second IDT 20b when in operation will propagate toward the second fingers 32. When the main mode of the surface acoustic wave is transmitted to the second fingers 32, the second fingers 32 are used to reflect the main mode. Thus, the main mode of the surface acoustic wave generated by the second IDT 20b when in operation is confined within the second IDT 20b.

[0186] In one embodiment, the number of first fingers 31 is less than the number of second fingers 32, and the number of first fingers 31 is greater than or equal to the number of third fingers 33. The third fingers 33 are used to block the mutual influence of surface acoustic waves generated by the two IDTs 20 when they are working.

[0187] The first reflection grating 30 has a relatively large number of first fingers 31 and second fingers 32, which can ensure the reflection effect of the first reflection grating 30 on the two IDTs 20. A smaller number of third fingers 33 is provided, which can block the mutual influence of the surface acoustic waves generated by the two IDTs 20 when working, while ensuring the overall size of the first reflection grating 30, thereby improving the Q value of the filter 100 of the present application.

[0188] In one embodiment, the number of the first fingers 31 and the number of the second fingers 32 are both multiple, and the finger spacing between two adjacent first fingers 31 is greater than the finger spacing between two adjacent second fingers 32, so as to respectively match the main modes of different IDTs 20, so that the first reflection grating 30 can simultaneously realize the reflection of the surface acoustic waves of two IDTs 20 with different main modes. This improves the working range of the filter 100 of the present application.

[0189] In one 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 of the present application adjusts the ratio of the number of the first fingers 31, the second fingers 32, and the third fingers 33 based on the finger spacing between two adjacent first fingers 31 and the finger spacing between two adjacent second fingers 32, so as to further improve the Q value of the filter 100 of the present application while ensuring the reflection effect of the first reflection grating 30 on the main modes of the two interdigital transducers 20.

[0190] In one 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 reflection grating is positively correlated with the reflection effect of the reflection grating on the surface acoustic wave. The filter 100 of the present application controls the sum of the number of the first fingers 31, the second fingers 32 and the third fingers 33 to ensure the reflection effect of the first fingers 31 and the second fingers 32 on the surface acoustic waves generated when the corresponding interdigital transducers 20 are working, and the blocking effect of the third fingers 33 on the surface acoustic waves generated when the two interdigital transducers 20 are working. In this way, the Q value of the filter 100 of the present application is guaranteed.

[0191] In one embodiment, the sum of the numbers 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 beneficial to the miniaturization of the filter 100 of the present application.

[0192] In one 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 spacing of the first IDT 20a is a first finger spacing F1, and the spacing between the first finger 31 adjacent to the first IDT 20a and the central axis of the adjacent first electrode finger 22a is equal to the first finger spacing F1; the finger spacing of the second IDT 20b is a second finger spacing F2, and the spacing between the second finger 32 adjacent to the second IDT 20b and the central axis of the adjacent second electrode finger 22b is equal to the second finger spacing F2, and the first finger spacing F1 is greater than the second finger spacing F2.

[0193] Since the main mode frequency of the first IDT 20a is determined by the finger spacing between two adjacent first electrode fingers 22a in the first IDT 20a, the filter 100 of the present application sets the finger spacing between two adjacent first electrode fingers 22a and the spacing between the first finger 31 adjacent to the first IDT 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 fingers 31 can achieve reflection of the main mode of the first IDT 20a.

[0194] Since the main mode frequency of the second IDT 20b is determined by the finger spacing between two adjacent second electrode fingers 22b in the second IDT 20b, the filter 100 of the present application sets the finger spacing between two adjacent second electrode fingers 22b and the spacing between the central axis of the second finger 32 adjacent to the second IDT 20b and the adjacent second electrode finger 22b to the second finger spacing F2, so as to ensure that the plurality of second fingers 32 can achieve reflection of the main mode of the second IDT 20b.

[0195] In one embodiment, the filter 100 of the present application further includes a second reflection grating 40 and a third reflection grating 50. Along the first direction 001, the first interdigital transducer 20a and the second reflection grating 40 are located on a first side of the first reflection grating 30, and the second interdigital transducer 20b and the third reflection grating 50 are located on a 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 provided on opposite sides of the first interdigital transducer 20a. The first reflection grating 30 and the second reflection grating 40 cooperate with each other to realize the constraint of the surface acoustic wave generated when the first interdigital transducer 20a is working. Specifically, during the operation of the filter 100 of the present 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 reflection grating 30 and the second reflection grating 40 respectively, and the main mode propagated to the first reflection grating 30 will be reflected by the plurality of first fingers 31.

[0197] The second reflection grating 40 includes a plurality of fourth fingers 41. The main mode propagating to the second reflection grating 40 is reflected toward the first IDT 20a under the action of the plurality of fourth fingers 41. Thus, the main mode generated by the first IDT 20a is constrained, and the Q value of the first IDT 20a is improved.

[0198] Along the first direction 001, the first reflection grating 30 and the third reflection grating 50 are respectively provided on the opposite sides of the second IDT 20b. The first reflection grating 30 and the third reflection grating 50 cooperate with each other to realize the constraint of the surface acoustic wave generated by the second IDT 20b when it is working. Specifically, during the operation of the filter 100 of the present application, the main mode of the surface acoustic wave generated by the second IDT 20b when it is working will propagate along the first direction 001 to the first reflection grating 30 and the third reflection grating 50 respectively, and the main mode propagated to the first reflection grating 30 will be reflected by the plurality of second fingers 32.

[0199] The third reflection grating 50 includes a plurality of fifth fingers 51. The surface acoustic wave propagating to the third reflection grating 50 is reflected toward the second IDT 20b under the action of the plurality of fifth fingers 51. Thus, the main mode generated by the second IDT 20b is constrained, and the Q value of the second IDT 20b is improved.

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

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

[0202] Based on the limitations of the above two embodiments, the filter 100 of the present application adjusts the size relationship between the total number of fingers of the first reflection grating 30 and the number of fourth fingers 41 and the number of fifth fingers 51, so as to ensure the reflection effect of the first fingers 31 and the second fingers 32 in the first reflection grating 30 on the two interdigital transducers 20 on the one hand, and control the overall size of the first reflection grating 30 on the other hand, so as to facilitate the miniaturization of the filter 100.

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

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

[0205] In one embodiment, along the first direction 001, the spacing between the central axes of two adjacent fifth fingers 51 is the fifth finger spacing F5, the spacing between the central axes of two adjacent second electrode fingers 22b in the second interdigital transducer 20b is equal to the fifth finger spacing F5, and the spacing between the central axes of adjacent fifth fingers 51 and second electrode fingers 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 between two adjacent second electrode fingers 22b in the second IDT 20b, the filter 100 of the present application sets the finger spacing between two adjacent second electrode fingers 22b, the spacing between the adjacent fifth fingers 51 and the central axis of the second electrode finger 22b, and the finger spacing between two adjacent fifth fingers 51 to the fifth finger spacing F5, so as to ensure that the plurality of fifth fingers 51 can achieve reflection of the main mode of the second IDT 20b.

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

[0208] Figure 17-Figure 22 This is a comparison chart of the conductivity curves of the filter 100 of the present application, the filter in the comparative example and the filter in reference example 1 based on different surface acoustic wave frequencies. Figure 17-Figure 22 The horizontal axis is frequency in MHz, and the vertical axis is conductance in dB. Figure 23-Figure 28 This is a comparison chart of the Q values ​​of the filters 100 of the present application, the comparative example and the reference example 1 based on different surface acoustic wave frequencies. Figure 23-Figure 28 The horizontal axis is frequency in MHz, and the vertical axis is Q value.

[0209] For each embodiment, each comparative example and reference example 1, the filter includes two interdigital transducers, the two interdigital transducers are respectively a first interdigital transducer and a second interdigital transducer. For the first interdigital transducer, the finger spacing between two adjacent 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 material of the electrode fingers is aluminum, the material of the piezoelectric substrate is LiTaO3, and the thickness of the electrode fingers is 410 nm.

[0210] For the second interdigital transducer, the finger spacing between two adjacent 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 material of the piezoelectric substrate is LiTaO3, and the thickness of the electrode fingers is 410 nm.

[0211] Based on the structures of the above two IDTs, each comparative example includes three reflection gratings arranged at intervals, each IDT is located between two adjacent reflection gratings, and each reflection grating has 20 fingers.

[0212] There are three groups of comparative examples, namely, comparative example 1 to comparative example 3, and the distribution ratio of the number of reflection gratings between two interdigital transducers in each comparative example is different. In the comparative examples, each finger of the shared reflection grating is a plurality of first fingers and a plurality of second fingers. In the comparative examples, the spacing between two adjacent first fingers, the spacing between adjacent first fingers and the electrode fingers of the first interdigital transducer, and the finger spacing between two adjacent electrode fingers in the first interdigital transducer are all equal. At this time, the number of first fingers is the number of fingers allocated to the first interdigital transducer in the shared reflection grating. Correspondingly, the spacing between two adjacent second fingers, the spacing between adjacent second fingers and the electrode fingers of the second interdigital transducer, and the finger spacing between two adjacent electrode fingers in the second interdigital transducer are all equal. At this time, the number of second fingers is the number of fingers allocated to the second interdigital transducer in the shared reflection grating. Therefore, the distribution ratio of the number of reflection gratings between the two interdigital transducers in each comparison example is different, which means that in different comparison examples, the ratio of the number of fingers allocated to the first interdigital transducer to the number of fingers allocated to the second interdigital transducer is different, that is, the ratio of the number of first fingers to the number of second fingers is different in each comparison example.

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

[0214] In each embodiment, based on the structure of the above two interdigital transducers 20, the first reflective grating 30, the second reflective grating 40 and the third reflective grating 50 each include 20 fingers. There are three embodiments, namely, Embodiment 1 to Embodiment 3, and the number distribution ratio of the first fingers 31, the second fingers 32 and the third fingers 33 in the first reflective grating 30 is different in each embodiment. Among them, the third finger spacing F3 is 2.915 μm.

[0215] Specifically, in Example 1, the number distribution ratio of the first finger 31, the third finger 33 and the second finger 32 is 5:5:10. In Example 2, the number distribution ratio of the first finger 31, the third finger 33 and the second finger 32 is 10:5:5. In Example 3, the number distribution ratio of the first finger 31, the third finger 33 and the second finger 32 is 6:5:9.

[0216] Reference Example 1 Based on the structure of the above two IDTs, Reference Example 1 includes four reflection gratings, one of which is provided on opposite sides of each IDT, and the two IDTs are spaced apart. Each reflection grating includes 20 fingers.

[0217] Based on the above three comparative examples, three embodiments and one reference example 1, the conductivity curves and Q value curves are simulated and formed respectively. Figure 17-Figure 28 Each of the figures includes a conductance curve or Q value curve corresponding to the first interdigital transducer represented by a solid line, and a conductance curve or Q value curve corresponding to the second interdigital transducer represented by a dotted line. Figure 17-Figure 22 In the legend, the conductivity curve corresponding to reference example 1 is consistent. Figure 23-Figure 28 In the figure, the Q value curve corresponding to reference example 1 is also consistent.

[0218] Specifically, Figure 17-Figure 19 They are comparison diagrams of the conductance curves corresponding to the two interdigital transducers in Comparative Examples 1 to Comparative Examples 3 and Reference Example 1. Figure 20-Figure 22 They are comparison diagrams of the conductance curves corresponding to the two interdigital transducers in Examples 1 to 3 and Reference Example 1. Figure 23-Figure 25 They are comparison diagrams of Q value curves corresponding to the two interdigital transducers in comparative examples 1 to comparative examples 3 and reference example 1. Figure 26-Figure 28 They are comparison diagrams of Q value curves corresponding to the two interdigital transducers in Examples 1 to 3 and Reference Example 1.

[0219] like Figure 17-Figure 19 ,as well as Figure 23-Figure 25 As shown, the more fingers are allocated to any IDT in Comparative Examples 1 to 3, the better the consistency of the conductance curve or Q value curve corresponding to the IDT and the conductance curve or Q value curve corresponding to Reference Example 1.

[0220] contrast Figure 17-Figure 28 It can be seen that the conductivity curves and Q value curves corresponding to Examples 1 to 3 are more consistent with those of Reference Example 1 than those of Comparative Example 1 to 3. For example, the conductivity curve comparison diagram of Comparative Example 1 and Example 1 is used for comparison. Since the number of second fingers 32 in Example 1 is the largest, the comparison Fig. 20 and Fig.17 It can be seen that the conductance curve corresponding to the second IDT 20b of Example 1 is more consistent with the corresponding conductance curve of Reference Example 1, while the conductance curve corresponding to the first IDT 20a of Example 1 is significantly more consistent with Reference Example 1 than Comparative Example 1.

[0221] Similarly, referring to the above figures, it is obvious that the conductivity curve obtained for Example 2 is also consistent with that of Reference Example 1 compared with that of Comparative Example 2. The Q value curves obtained for Example 1 and Example 2 are also consistent with that of Reference Example 1 compared with that of Comparative Example 1 and Comparative Example 2.

[0222] This is because the third finger 33 is provided in Examples 1 and 2 of the present application, and the third finger 33 is used 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 the present application and improving the Q value of the filter 100 of the present application.

[0223] In Comparative Examples 1 to 3, the conductance curve and Q value curve corresponding to Comparative Example 3 are more consistent with the conductance curve and Q value curve corresponding to Reference Example 1. In the embodiment of the present application, the number of the second fingers 32 is greater than or equal to the number of the third fingers 33, and less than or equal to the number of the first fingers 31, corresponding to the conductance curve and Q value curve corresponding to Example 3.

[0224] By comparison Fig.19 and Fig. 22 ,as well as Fig.25 and Fig.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 the present application sets a third finger 33, and adjusts the quantitative relationship between the third finger 33 and the first finger 31 and the second finger 32, so as to make full use of the third finger 33 to block the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 when working, thereby improving the performance of the filter 100 of the present application and improving the Q value of the filter 100 of the present application.

[0225] It is worth pointing out that the finger allocation ratio schemes proposed in the above-mentioned comparative examples 1 to 3 and embodiments 1 to 3 of the present application will not affect the resonant frequency, electromechanical coupling coefficient, static capacitance and other characteristics of the filter. Figure 17-Figure 28 The differences in consistency in the examples shown are all due to characteristics such as the filter's resonant frequency, electromechanical coupling coefficient, static capacitance, etc.

[0226] Specifically, Fig.29 It is a comparison diagram of the admittance curves of Comparative Examples 1 to 3 and Reference Example 1. Fig.30 It is a comparison diagram of the admittance curves of Examples 1 to 3 and Reference Example 1. Among them, Fig.29 and Fig.30 The horizontal axis is frequency in MHz, and the vertical axis is admittance in dB. Fig.29 and Fig.30 The solid line represents the admittance curve corresponding to the first interdigital transducer, and the dotted line represents the admittance curve corresponding to the second interdigital transducer. In order to facilitate the comparison of the curve consistency between each comparative example or embodiment and reference example 1, the ordinate of the admittance curve corresponding to each comparative example and each embodiment is processed. In the figure, it is reflected that the curves of each comparative example and each embodiment have a certain displacement along the ordinate. Specifically, Fig.29 In the direction of -100 dB along the ordinate, the curves are Comparative Example 3, Comparative Example 2, Comparative Example 1 and Reference Example 1. Fig.30 In the figure, along the vertical axis toward -100 dB, the curves are Example 3, Example 2, Example 1 and Reference Example 1, respectively.

[0227] like Fig.29 and Fig.30 It can be seen that the admittance curves of each comparative example and each embodiment are consistent with the admittance curve of reference example 1. Correspondingly, the finger allocation ratio schemes proposed in the comparative examples 1 to 3 and embodiments 1 to 3 of the present application will not affect the resonant frequency, electromechanical coupling coefficient, static capacitance and other characteristics of the filter.

[0228] To further support the viewpoint of this application, Figure 31-Figure 37 This is a comparison chart of the conductivity curves of the filter 100 of the present application, the filter in the comparative example and the filter in reference example 2 based on different surface acoustic wave frequencies. Figure 31-Figure 37 The horizontal axis is frequency in MHz, and the vertical axis is conductance in dB. Figure 38-Figure 44 This is a comparison chart of Q values ​​of the filter 100 of the present application, the filter in the comparative example and the filter in reference example 2 based on different surface acoustic wave frequencies. Figure 38-Figure 44 The horizontal axis is frequency in MHz, and the vertical axis is Q value.

[0229] Among them, there are three groups of comparative examples, namely, comparative example 4 to comparative example 6. There are four groups of embodiments, namely, embodiment 4 to embodiment 7. The filters of comparative example 4 to comparative example 6 and embodiment 4 to embodiment 7 all include two interdigital transducers, and the two interdigital transducers are respectively a first interdigital transducer and a second interdigital transducer. Among them, for the first interdigital transducer, the finger spacing between two adjacent electrode fingers is 2.8μm, the duty cycle of the electrode fingers is 0.42, the aperture size is 140μm, the number of electrode fingers is 131, the material of the electrode fingers is aluminum, the material of the piezoelectric substrate is LiTaO3, and the thickness of the electrode fingers is 410nm.

[0230] For the second interdigital transducer, the finger spacing between two adjacent 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 material of the piezoelectric substrate is LiTaO3, and the thickness of the electrode fingers is 410 nm.

[0231] Each comparative example includes three reflection gratings on the basis of the structures of the above two IDTs, and the three reflection gratings are arranged at intervals, and each IDT is located between two adjacent reflection gratings. Among them, the number of fingers of the reflection grating located on the side of the first IDT away from the second IDT is 30, the number of fingers of the reflection grating located on the side of the second IDT away from the first IDT is 20, and the number of fingers of the reflection grating located between the first IDT and the second IDT is 25.

[0232] The number distribution ratio of the reflection grating between the two interdigital transducers in each comparative example is different. Among them, the number distribution ratio of the shared reflection grating is different. As mentioned above, each finger of the shared reflection grating is a plurality of first fingers and a plurality of second fingers.

[0233] Specifically, the root number distribution ratio of the first finger line to the second finger line in comparative example 4 is 8:17. The root number distribution ratio of the first finger line to the second finger line in comparative example 5 is 17:8. The root number distribution ratio of the first finger line to the second finger line in comparative example 6 is 12:13.

[0234] In each embodiment, based on the structure of the two interdigital transducers 20, the first reflection grating 30 includes 30 fingers, the second reflection grating 40 includes 20 fingers, and the third reflection grating 50 includes 25 fingers. In each embodiment, the number distribution ratio of the first fingers 31, the second fingers 32 and the third fingers 33 in the first reflection grating 30 is different. The third finger spacing F3 is equal to 2.915 μm.

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

[0236] Reference Example 2 is based on the structure of the above two IDTs, and Reference Example 2 includes four reflection gratings, each of which is provided with a reflection grating on two opposite sides of each IDT, and the two IDTs are spaced apart. The number of fingers of the two reflection gratings on the opposite sides of the first IDT is 30, and the number of fingers of the two reflection gratings on the opposite sides of the second IDT is 20.

[0237] Based on the above three comparative examples, four embodiments and one reference example 2, the conductivity curves and Q value curves are simulated and formed respectively. Figure 31-Figure 44 Each of the figures includes a conductance curve or Q value curve corresponding to the first interdigital transducer represented by a solid line, and a conductance curve or Q value curve corresponding to the second interdigital transducer represented by a dotted line. Figure 31-Figure 44 In the legend, the conductivity curve or Q value curve corresponding to Reference Example 2 remains consistent.

[0238] Specifically, Figure 31-Figure 33 They are comparison diagrams of the conductance curves corresponding to the two interdigital transducers in Comparative Examples 4 to Comparative Examples 6 and Reference Example 2. Figure 34-Figure 37 They are comparison diagrams of the conductance curves corresponding to the two interdigital transducers in Examples 4 to 7 and Reference Example 2. Figure 38-Figure 40 They are comparison diagrams of Q value curves corresponding to the two interdigital transducers in Comparative Examples 4 to Comparative Examples 6 and Reference Example 2. Figure 41-44 They are comparison diagrams of Q value curves corresponding to the two interdigital transducers in Examples 4 to 7 and Reference Example 2.

[0239] By comparing the above figures, it is obvious that the conductivity curves and Q value curves obtained for Examples 4 to 7 are more consistent with those of Reference Example 2 than those of Comparative Examples 4 to 6. This is because Examples 4 to 7 of the present application are provided with a third finger 33, which blocks the mutual influence of the surface acoustic waves generated by the two interdigital transducers 20 when they are working, thereby improving the performance of the filter 100 of the present application and improving the Q value of the filter 100 of the present application.

[0240] It should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the embodiments of the present application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0241] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0242] It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in the field, improvements or changes can be made according to the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to this application. Ordinary technicians in the field can understand that all or part of the processes of the above embodiments are implemented, and equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims

1. A filter, characterized in that: It comprises a piezoelectric substrate, a first reflection grating and two interdigital transducers arranged on the surface of the piezoelectric substrate, wherein the two interdigital transducers are arranged on two opposite sides of the first reflection grating; The first reflective grating includes a first finger, a second finger and a third finger connected to each other, wherein the first finger and the second finger are arranged on both sides of the third finger along a first direction; wherein, The spacing between the third finger adjacent to the first finger and the central axis of the adjacent first finger is a first spacing, and the spacing between the third finger adjacent to the second finger and the central axis of the adjacent second finger is a second spacing, and the first spacing is not equal to the second spacing.

2. The filter according to claim 1, characterized in that The number of the first fingers and the second fingers is plural, the number of the third fingers is one, the plurality of the first fingers, the third fingers, and the plurality of the second fingers are arranged at intervals along the first direction, the distance between the central axes of two adjacent first fingers is a first finger distance, and the distance between the central axes of two adjacent second fingers is a second finger distance; The difference between twice the first spacing and the first finger spacing is defined as a third finger spacing; and / or the difference between twice the second spacing and the second finger spacing is defined as a third finger spacing; The third finger spacing is greater than the first finger spacing and the second finger spacing.

3. The filter according to claim 2, characterized in that The difference between twice the first spacing and the first finger spacing is equal to the difference between twice the second spacing and the second finger spacing.

4. The filter according to claim 1, characterized in that The number of the first finger strips, the second finger strips and the third finger strips is multiple, and the multiple first finger strips, the multiple third finger strips and the multiple second finger strips are arranged at intervals along the first direction; The spacing between the central axes of two adjacent first fingers is the first finger spacing, the spacing between the central axes of two adjacent second fingers is the second finger spacing, and the spacing between the central axes of two adjacent third fingers is the third finger spacing, which is greater than the first finger spacing and the second finger spacing.

5. The filter according to claim 4, characterized in that 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.

6. The filter according to any one of claims 2 to 5, 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, Along 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 a third finger adjacent to the first finger and the adjacent first finger is greater than the first gap size, and the gap size between a third finger adjacent to the second finger and the adjacent second finger is greater than the second gap size.

7. The filter according to any one of claims 2 to 5, characterized in that: A ratio of the third finger spacing to the first finger spacing is greater than or equal to 1.

01.

8. The filter according to any one of claims 2 to 5, characterized in that: The third finger spacing is less than or equal to 1.04 times the first finger spacing.

9. The filter according to any one of claims 2 to 5, characterized in that: The third finger spacing is less than or equal to 1.1 times of the first finger spacing.

10. The filter according to any one of claims 1 to 5, characterized in that: The two IDTs include a first IDT and a second IDT, along the first direction, the first IDT and the first finger are located on a first side of the third finger, the second IDT and the second finger are located on a second side of the third finger, the first IDT includes a plurality of first electrode fingers, and the second IDT includes a plurality of second electrode fingers; wherein, The finger spacing of the first IDT is equal to the first finger spacing, and the spacing between the first finger adjacent to the first IDT and the central axis of the adjacent first electrode finger is equal to the first finger spacing; The finger pitch of the second IDT is equal to the second finger pitch, the spacing between the second finger strip adjacent to the second IDT and the central axis of the adjacent second electrode finger is equal to the second finger pitch, and the first finger pitch is greater than the second finger pitch.

11. The filter according to any one of claims 1 to 5, characterized in that: The number of the first fingers is multiple, the number of the second fingers is multiple, and the number of the first fingers and the number of the second fingers are both greater than or equal to the number of the third fingers.

12. The filter according to claim 11, characterized in that The number of the first fingers is less than or equal to the number of the second fingers.

13. The filter according to any one of claims 1 to 5, characterized in that: The ratio of the number of the second fingers, the number of the third fingers, and the number of the first fingers is 2:1:

1.

14. The filter according to any one of claims 1 to 5, characterized in that: The sum of the number of the first fingers, the second fingers and the third fingers is greater than or equal to 10.

15. The filter according to any one of claims 1 to 5, characterized in that: The sum of the number of the first fingers, the second fingers and the third fingers is less than or equal to 40.

16. The filter according to any one of claims 1 to 5, characterized in that: The first direction is the arrangement direction of the two IDTs.

17. The filter according to any one of claims 1 to 5, characterized in that: The finger spacings of the two interdigital transducers are not equal.

18. The filter according to any one of claims 1 to 5, characterized in that: The filter further comprises a second reflection grating and a third reflection grating, the two IDTs comprise a first IDT and a second IDT, along the first direction, the first IDT and the second reflection grating are located on a first side of the first reflection grating, and the second IDT and the third reflection grating are located on a second side of the first reflection grating; The second reflective grating includes a plurality of fourth fingers, and the third reflective grating includes a plurality of fifth fingers; The sum of the number of the first fingers, the second fingers and the third fingers is greater than or equal to the smallest one of the number of the fourth fingers and the number of the fifth fingers; And / or, the sum of the number of the first fingers, the second fingers and the third fingers is less than or equal to the largest one of the number of the fourth fingers and the number of the fifth fingers.

19. The filter according to claim 18, characterized in that 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 adjacent fourth fingers and electrode fingers is equal to the fourth finger spacing; Along the first direction, the spacing between the central axes of two adjacent fifth fingers is the 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 adjacent fifth fingers and electrode fingers is equal to the fifth finger spacing.

20. The filter according to any one of claims 1 to 5, characterized in that: Each of the IDTs comprises two bus bars arranged in parallel and at intervals, 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 another of the bus bars, and the electrode fingers connected to different bus bars being arranged alternately; Along the arrangement direction of the two bus bars, the distance between the ends of any two adjacent electrode fingers in each of the IDTs that are not connected to the bus bar is the aperture size, and the aperture sizes of the two IDTs are equal.

21. The filter according to claim 20, characterized in that The distance between the two bus bars of each IDT is equal, and the length of the first finger, the length of the second finger and the length of the third finger are all equal to the distance between the two bus bars of any IDT.

22. A filter, characterized in that: It comprises a piezoelectric substrate, a first reflection grating and two interdigital transducers arranged on the surface of the piezoelectric substrate, wherein the two interdigital transducers are arranged on two opposite sides of the first reflection grating; The first reflective grating includes a first finger, a second finger and a third finger connected to each other, wherein the first finger and the second finger are arranged on both sides of the third finger along a first direction; wherein the number of the first fingers is less than the number of the second fingers, and the number of the first fingers is greater than or equal to the number of the third fingers.

23. The filter according to claim 22, characterized in that The number of the first fingers and the number of the second fingers are both plural, and the distance between two adjacent first fingers is greater than the distance between two adjacent second fingers.

24. The filter according to claim 22, characterized in that The ratio of the number of the second fingers, the number of the third fingers, and the number of the first fingers is 2:1:

1.

25. The filter according to claim 22, characterized in that The sum of the number of the first fingers, the second fingers and the third fingers is greater than or equal to 10.

26. The filter according to claim 22, characterized in that The sum of the number of the first fingers, the second fingers and the third fingers is less than or equal to 40.

27. The filter according to any one of claims 22 to 26, characterized in that: The two IDTs include a first IDT and a second IDT, along the first direction, the first IDT and the first finger are located on a first side of the third finger, the second IDT and the second finger are located on a second side of the third finger, the first IDT includes a plurality of first electrode fingers, and the second IDT includes a plurality of second electrode fingers; wherein, The finger spacing of the first IDT is a first finger spacing, and the spacing between the first finger adjacent to the first IDT and the central axis of the adjacent first electrode finger is equal to the first finger spacing; The finger pitch of the second IDT is a second finger pitch, the spacing between the second fingers adjacent to the second IDT and the central axis of the adjacent second electrode fingers is equal to the second finger pitch, and the first finger pitch is greater than the second finger pitch.

28. The filter according to any one of claims 22 to 26, characterized in that: The filter further comprises a second reflection grating and a third reflection grating, the two IDTs comprise a first IDT and a second IDT, along the first direction, the first IDT and the second reflection grating are located on a first side of the first reflection grating, and the second IDT and the third reflection grating are located on a second side of the first reflection grating; The second reflective grating includes a plurality of fourth fingers, and the third reflective grating includes a plurality of fifth fingers; The sum of the number of the first fingers, the second fingers and the third fingers is greater than or equal to the smallest one of the number of the fourth fingers and the number of the fifth fingers; And / or, the sum of the number of the first fingers, the second fingers and the third fingers is less than or equal to the largest one of the number of the fourth fingers and the number of the fifth fingers.

29. The filter according to claim 28, characterized in that 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 adjacent fourth fingers and electrode fingers is equal to the fourth finger spacing; Along the first direction, the spacing between the central axes of two adjacent fifth fingers is the 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 adjacent fifth fingers and electrode fingers is equal to the fifth finger spacing.

30. A radio frequency front-end module, characterized in that: Comprising a filter as described in any one of claims 1-29.

31. An electronic device, characterized in that: Comprising the RF front-end module as described in claim 30.

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