Filter, multiplexer, radio frequency front-end module and electronic equipment

Abstract

The invention relates to a filter, a multiplexer, a radio frequency front-end module and electronic equipment. The filter comprises a substrate and a plurality of series resonators arranged on the substrate at intervals, the substrate comprises a signal input end, a signal output end and a grounding terminal, the signal input end is used for receiving external signals, the signal output end is used for outputting the external signals, and the series resonators are sequentially connected between the signal input end and the signal output end in series; wherein each series resonator comprises an interdigital transducer and reflecting gratings located on the two sides of the interdigital transducer, and the reflecting grating on at least one side of each interdigital transducer is electrically connected with the grounding terminal through a metal layer. According to the filter, the reflecting grating of the series resonator is grounded through the metal layer, so that the reflecting grating is in a zero potential state. Therefore, signal attenuation is reduced, and the out-of-band rejection capability and isolation of the filter are improved.

Description

Technical Field

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

[0002] In the field of radio frequency, a filter usually consists of a substrate and a plurality of resonators disposed on the substrate. Through the series and / or parallel relationship of each resonator, the filter realizes the regulation and transmission of signals. Among them, the mutual cooperation between the interdigital transducer and the reflection grating in each resonator is used to realize the filtering function of the filter.

[0003] In the related art, since the interdigital transducer and the reflection grating are usually disposed on a piezoelectric substrate, based on the piezoelectric effect of the piezoelectric substrate, when the surface acoustic wave propagates to the reflection grating, the reflection grating may cooperate with the piezoelectric substrate to convert the surface acoustic wave into an electrical signal, so that the reflection grating has a potential, which in turn leads to a decrease in the out-of-band rejection ability and isolation of the filter. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a solution for improving the out-of-band rejection ability and isolation of a filter, specifically including the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a filter, including a substrate and a plurality of series resonators arranged at intervals on the substrate. The substrate includes a signal input terminal, a signal output terminal, and a ground terminal. The signal input terminal is used to receive an external signal, the signal output terminal is used to output a signal, and the plurality of series resonators are connected in series between the signal input terminal and the signal output terminal; wherein,

[0006] Each series resonator includes an interdigital transducer and reflection gratings located on both sides of the interdigital transducer. The reflection grating on at least one side of each interdigital transducer is electrically connected to the ground terminal through a metal layer.

[0007] The filter provided by the present application realizes the filtering function of the filter of the present application by connecting a plurality of series resonators in series between the signal input terminal and the signal output terminal, so that the signal input through the signal input terminal can be output from the signal output terminal at a specific frequency band under the cooperation of each series resonator. Among them, the interdigital transducer of each series resonator is used to cooperate to realize the mutual conversion between electrical signals and acoustic signals, and the reflection grating is used to constrain the surface acoustic wave generated when the interdigital transducer works.

[0008] The filter provided by the present application also sets a metal layer and a grounding terminal on the substrate, and connects one end of the metal layer to the grounding terminal and the other end to the reflection grating on at least one side of each interdigital transducer, so that the reflection grating on at least one side of each interdigital transducer is grounded. Thus, the reflection grating is in a zero-potential state, thereby reducing signal attenuation and improving the out-of-band rejection ability and isolation of the filter of the present application.

[0009] In one embodiment, the arrangement directions of the reflection gratings of each series resonator are parallel to each other, and the arrangement direction of the reflection grating of any one series resonator intersects with the arrangement directions of multiple series resonators.

[0010] In one embodiment, the reflection gratings on both sides of at least some series resonators are electrically connected to the grounding terminal through the metal layer.

[0011] In one embodiment, the number of grounding terminals is two, and the two grounding terminals are arranged at intervals along the arrangement direction of the reflection gratings of the series resonator, and the reflection gratings of at least some series resonators are respectively electrically connected to the grounding terminal on the same side.

[0012] In one embodiment, multiple reflection gratings on one side of the interdigital transducer are electrically connected to the grounding terminal through the metal layer.

[0013] In one embodiment, along the arrangement direction of the reflection gratings of the series resonator, each reflection grating on at least one side of the interdigital transducer is electrically connected to the grounding terminal through a metal layer.

[0014] In one embodiment, the multiple series resonators include at least two first series resonators, the metal layer includes a first metal layer, and the first series resonators are electrically connected to the grounding terminal through the first metal layer; wherein, along the arrangement direction of the multiple series resonators, at least two first series resonators are located on the same side of the grounding terminal, the first metal layer extends towards the grounding terminal, and along the arrangement directions of the two reflection gratings of the series resonator, it is electrically connected to the reflection gratings of at least two first series resonators.

[0015] In one embodiment, along the arrangement direction of the reflection gratings of the series resonator, the first metal layer is located on the side of the reflection grating away from the interdigital transducer.

[0016] In one embodiment, the multiple series resonators further include at least one second series resonator, and along the arrangement direction of the multiple series resonators, at least two first series resonators and at least one second series resonator are arranged at intervals in sequence; wherein, among adjacent first series resonators and second series resonators, the distance between the first series resonator and a side wall of the substrate is less than the distance between the second series resonator and the side wall, and the grounding terminal is located between the second series resonator and the side wall.

[0017] In one embodiment, along the arrangement direction of a plurality of series resonators, among any two adjacent first series resonators, the distance between one first series resonator and the sidewall is greater than the distance between the other first series resonator and the sidewall, and the first series resonator with a larger distance from the sidewall is closer to the ground terminal.

[0018] In one embodiment, the first metal layer includes a connected extension section and a connection section. The extension section extends towards the ground terminal along the arrangement direction of the plurality of series resonators, and the connection section extends towards the direction of the reflection grating; wherein, the extension section is electrically connected to the ground terminal, and the reflection grating of at least one first series resonator is electrically connected to the extension section through the connection section.

[0019] In one embodiment, the connection section is electrically connected to the reflection grating through at least one contact point.

[0020] In one embodiment, the number of contact points is multiple, and the multiple contact points are arranged at intervals along the arrangement direction of the plurality of series resonators.

[0021] In one embodiment, the distance between any two adjacent contact points of any one connection section is equal, and the width of each contact point is less than or equal to the width of the extension section.

[0022] In one embodiment, the material of the metal layer includes at least one of aluminum, copper, titanium, chromium, gold, and silver.

[0023] In one embodiment, the metal layer is located on the surface of the substrate, and the metal layer extends towards the ground terminal along the plane direction of the substrate; wherein, along the direction perpendicular to the extension direction of the metal layer, the width of the metal layer is greater than or equal to 0.3 μm.

[0024] In one embodiment, the metal layer and the reflection grating are arranged on the same layer.

[0025] In one embodiment, the width of the metal layer is greater than or equal to 1 μm and less than or equal to 5 μm.

[0026] In one embodiment, along the arrangement direction of the two reflection gratings of the series resonator, the metal layer is connected to the side of the reflection grating away from the interdigital transducer.

[0027] In one embodiment, the filter further includes a plurality of parallel resonators, and the plurality of parallel resonators are arranged at intervals on the surface of the substrate and are spaced from the series resonators; wherein, one end of each parallel resonator is electrically connected between any two adjacent series resonators, and the other end is grounded through the ground terminal.

[0028] In one embodiment, the metal layer and the parallel resonator are spaced from each other, and the distance between the metal layer and the parallel resonator is greater than or equal to 0.3 μm.

[0029] In one embodiment, each parallel resonator includes a second interdigital transducer and second reflection gratings located on both sides of the second interdigital transducer, and the arrangement directions of the second reflection gratings on both sides of each parallel resonator are parallel to the arrangement directions of the reflection gratings on both sides of the series resonator.

[0030] In a second aspect, an embodiment of the present application provides a multiplexer, including at least a transmit filter and a receive filter; the transmit filter includes a filter; and / or, the receive filter includes a filter.

[0031] In a third aspect, an embodiment of the present application provides a radio frequency front-end module, including a multiplexer.

[0032] In a fourth aspect, an embodiment of the present application provides an electronic device, including a radio frequency front-end module.

[0033] It can be understood that the electronic device, radio frequency front-end module, and multiplexer provided in the fourth to second aspects of the present application all have better out-of-band rejection ability and isolation degree because they adopt the filter provided in the first aspect of the present application. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of an electronic device provided in an embodiment of the present application;

[0035] Figure 2 It is a schematic structural diagram of a radio frequency front-end module provided in an embodiment of the present application;

[0036] Figure 3 It is a schematic structural diagram of a multiplexer provided in an embodiment of the present application;

[0037] Figure 4 It is a schematic topological structure diagram of a filter provided in an embodiment of the present application;

[0038] Figure 5 It is a schematic structural diagram of a filter provided in an embodiment of the present application;

[0039] Figure 6 It is a schematic partial structural diagram of a filter provided in an embodiment of the present application;

[0040] Figure 7 It is another schematic partial structural diagram of a filter provided in an embodiment of the present application;

[0041] Figure 8 It is a curve comparison diagram of the out-of-band rejection of a filter provided in an embodiment of the present application and a filter in a comparative example based on a certain frequency;

[0042] Figure 9The figure shows the comparison of the out-of-band rejection curves of the filter provided in an embodiment of the present application and the filter in the comparative example based on another frequency;

[0043] Figure 10 The figure shows the comparison of the isolation curves of the filter provided in an embodiment of the present application and the filter in the comparative example based on different frequencies;

[0044] Figure 11 Another structural schematic diagram of the filter provided in an embodiment of the present application;

[0045] Figure 12 Still another structural schematic diagram of the filter provided in an embodiment of the present application;

[0046] Figure 13 A partial enlarged structural schematic diagram of the filter provided in an embodiment of the present application;

[0047] Figure 14 Another partial enlarged structural schematic diagram of the filter provided in an embodiment of the present application;

[0048] Figure 15 Yet another partial enlarged structural schematic diagram of the filter provided in an embodiment of the present application;

[0049] Figure 16 Still another partial enlarged structural schematic diagram of the filter provided in an embodiment of the present application;

[0050] Figure 17 A sectional structural schematic diagram of the filter provided in an embodiment of the present application;

[0051] Figure 18 Another sectional structural schematic diagram of the filter provided in an embodiment of the present application. Detailed implementation manners

[0052] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0053] The descriptions of the following embodiments refer to the appended drawings, which illustrate specific embodiments in which the present application can be implemented. The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meanings. The terms "connection" and "coupling" as used in the present application, unless otherwise specified, include both direct and indirect connections (couplings). The directional terms mentioned in the present application, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", etc., are only with reference to the directions in the appended drawings. Therefore, the directional terms are used to better and more clearly illustrate and understand 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 thus should not be construed as a limitation to the present application.

[0054] In the description of the present application, it should be noted that, unless otherwise clearly specified and defined, the terms "install", "connect", and "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations. It should be noted that the terms "first", "second", etc. in the specification, claims, and drawings of the present application are used to distinguish different objects rather than to describe a specific order. In addition, the terms "include", "may include", "comprise", or "may comprise" used in the present application indicate the existence of the corresponding functions, operations, elements, etc. disclosed, and do not limit the existence of one or more other functions, operations, elements, etc. In addition, the term "include" or "comprise" means the existence of the corresponding features, numbers, steps, operations, elements, components, or combinations thereof disclosed in the specification, and does not exclude the existence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, and is intended to cover non-exclusive inclusion.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0056] Please refer to Figure 1 the schematic structural diagram of the electronic device 400 provided in an embodiment of the present application as shown.

[0057] As Figure 1As shown, the electronic device 400 of the present application includes a substrate 401 and a radio frequency front-end module 300, and the radio frequency front-end module 300 is mounted on the substrate 401. Among them, the substrate 401 is electrically connected to the radio frequency front-end module 300.

[0058] In one embodiment, the substrate 401 includes a printed circuit board to achieve the working control of the radio frequency front-end module 300. The electronic device 400 of the present application realizes signal reception and / or transmission through the radio frequency front-end module 300. Exemplarily, the electronic device 400 includes at least one of a computer, a mobile phone, a tablet computer, a smart watch, and a navigator, etc., and the present application does not make special limitations on this.

[0059] Please refer to Figure 2 the schematic structural diagram of the radio frequency front-end module 300 provided in an embodiment of the present application shown in

[0060] As Figure 2 shown, the radio frequency front-end module 300 includes a signal terminal 301, a switch 302, an amplifier 303, and a filter 100. Among them, the signal terminal 301 is used to receive and transmit external signals. The switch 302 is communicatively connected between the signal terminal 301 and the filter 100 to control the signal transmission between the signal terminal 301 and the filter 100. The filter 100 is used to output the signal transmitted to the filter 100 as a signal with a preset frequency. The amplifier 303 is electrically connected to the filter 100 to amplify the signal processed by the filter 100 and output it to the subsequent structure. Among them, the signal terminal 301 can be set as an antenna.

[0061] It can be understood that in another embodiment, the filter 100 can also be one or multiple, and multiple filters 100 can form a multiplexer 200. The present application does not make special limitations on this.

[0062] Please refer to Figure 3 the schematic structural diagram of the multiplexer 200 provided in an embodiment of the present application shown in

[0063] As Figure 3 shown, the multiplexer 200 of the present application can be a duplexer or a triplexer, etc. The multiplexer 200 includes an antenna 201, a transmit filter 100a, and a receive filter 100b. Among them, both the transmit filter 100a and the receive filter 100b include opposite first ports 202 and second ports 203, and both the transmit filter 100a and the receive filter 100b are communicatively connected to the antenna 201.

[0064] For the transmit filter 100a, the first port 202 is used to transmit signals, and the second port 203 is used to receive signals. For the receive filter 100b, the first port 202 is used to receive signals, and the second port 203 is used to transmit signals.

[0065] Signals of different frequencies are input into the transmitting filter 100a from the first port 202. The transmitting filter 100a processes the signals of corresponding frequencies and transmits them outward from the antenna 201. Different signals are input into the receiving filter 100b from the antenna 201. The receiving filter 100b processes the corresponding signals and transmits them outward from the second port 203. Since the transmitting filter 100a and the receiving filter 100b are spaced apart from each other. It can be understood that the multiplexer 200 of the present application enables the transmitting filter 100a and the receiving filter 100b to work simultaneously. That is, the multiplexer 200 of the present application can receive signals and transmit signals simultaneously.

[0066] In the embodiment of the present application, the transmitting filter 100a is the filter 100 of the present application. Correspondingly, the antenna 201 is the signal output end 12 of the filter 100 of the present application, and the first port 202 of the transmitting filter 100a is the signal input end 11 of the filter 100 of the present application.

[0067] The receiving filter 100b is also the filter 100 of the present application. Correspondingly, the antenna 201 is the signal input end 11 of the filter 100 of the present application, and the second port 203 of the receiving filter 100b is the signal output end 12 of the filter 100 of the present application.

[0068] In some other embodiments, one of the transmitting filter 100a and the receiving filter 100b is the filter 100 of the present application.

[0069] Please refer to Figure 4 and Figure 5 , in which Figure 4 is a schematic diagram of the topological structure of the filter 100 provided in an embodiment of the present application, Figure 5 is a schematic diagram of the structure of the filter 100 provided in an embodiment of the present application.

[0070] As Figure 4 and Figure 5 shown, the filter 100 of the present application includes a substrate 10 and a plurality of series resonators 20. The plurality of series resonators 20 are arranged at intervals on the same surface of the substrate 10. The substrate 10 is used to carry and support the plurality of series resonators 20. The substrate 10 includes a signal input end 11, a signal output end 12 and a grounding terminal 13. The signal input end 11 is used to receive external signals, and the signal output end 12 is used to output signals.

[0071] Among them, the plurality of series resonators 20 are connected in series between the signal input end 11 and the signal output end 12 in sequence to cooperate to adjust the signals input into the signal input end 11 and allow the signals within the passband range formed by the cooperation of the plurality of series resonators 20 to pass through. Thus, the filtering function of the filter 100 of the present application is realized.

[0072] Please refer to Figure 6 the partial structural schematic diagram of a filter 100 provided in an embodiment of the present application as shown

[0073] As Figure 6 shown, the series resonator 20 of the present application includes an interdigital transducer 21 and a reflection grating 22, and the reflection grating 22 is located on opposite sides of the interdigital transducer 21. Among them, each interdigital transducer 21 includes two bus bars 211 arranged in parallel and spaced apart, and a plurality of electrode fingers 212 arranged in parallel and spaced apart. Among them, one of the two bus bars 211 is used to receive an external signal, and the other bus bar 211 of the two bus bars 211 is used to output a signal. The plurality of electrode fingers 212 are located between the two bus bars 211. Some of the plurality of electrode fingers 212 are connected to one bus bar 211, and the other part of the plurality of electrode fingers 212 are connected to the other bus bar 211.

[0074] For ease of description, the bus bar 211 for receiving an external signal is defined as the first bus bar 211a, and the bus bar 211 for outputting a signal is defined as the second bus bar 211b. The electrode finger 212 connected to the first bus bar 211a is defined as the first electrode finger 2121, and the electrode finger 212 connected to the second bus bar 211b is defined as the second electrode finger 2122.

[0075] Specifically, the first electrode fingers 2121 and the second electrode fingers 2122 are alternately arranged along the first direction 001. The first electrode fingers 2121 and the second electrode fingers 2122 both extend along the second direction 002. Specifically, as Figure 6 shown, along the first direction 001, there is a second electrode finger 2122 between any two adjacent first electrode fingers 2121, and there is a first electrode finger 2121 between any two adjacent second electrode fingers 2122.

[0076] Among them, the first direction 001 is the extension direction of the bus bar 211, that is, both the first bus bar 211a and the second bus bar 211b extend along the first direction 001. 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 212 has an angle of 90° with the bus bar to which it is connected. Exemplarily, the second direction 002 and the first direction 001 may also not be perpendicular, so that each electrode finger 212 has an angle greater than 90° or less than 90° with the bus bar 211 to which it is connected.

[0077] In an embodiment of the present application, when an external excitation signal is applied to the interdigital transducer 21, the interdigital transducer 21 converts the electrical signal into a surface acoustic wave. The surface acoustic wave propagates along the surface of a piezoelectric substrate (not shown in the figure) and is reflected by the reflection grating 22, and then is converted into an electrical signal by the interdigital transducer 21 for output.

[0078] Among them, the surface acoustic wave is used to implement the frequency selection function and signal processing function of the series resonator 20. During the propagation of the surface acoustic wave, the main propagation direction of the surface acoustic wave is the first direction 001. However, in actual processes, due to effects such as edge effects and acoustic wave diffraction, the propagation direction of the surface acoustic wave formed on the surface of the piezoelectric substrate may also be other directions. In one embodiment, the surface acoustic waves propagating in other directions are absorbed by an acoustic absorption material (not shown in the figure).

[0079] It can be understood that the series resonator in the present application can be applied to high-Q piezoelectric thin film on insulator type surface acoustic wave resonators (POI SAW resonators), conventional surface acoustic wave resonators (NSAW resonators), temperature compensated surface acoustic wave resonators (TCSAW resonators), and resonator devices formed by their certain topological interconnections, etc., including devices with interdigital transducers. The present application does not limit this.

[0080] In an embodiment of the present application, the number of reflection gratings 22 is two. It can be understood that in other embodiments, the number of reflection gratings 22 can also be other values, and the present application does not make special restrictions on this.

[0081] In Figure 4 and Figure 5 In the illustrated example, the filter 100 of the present application further includes a conduction layer 30. The conduction layer 30 is used to electrically connect the bus bars 211 of two adjacent series resonators 20, thereby realizing the series connection between two adjacent series resonators 20. The signal input terminal 11 and the signal output terminal 12 are respectively used to electrically connect to the bus bars 211 of different series resonators 20, thereby realizing the series connection of multiple series resonators 20 between the signal input terminal 11 and the signal output terminal 12. That is, in an embodiment of the present application, each series resonator 20 is connected to other structures through two bus bars 211.

[0082] In an embodiment of the present application, the filter 100 of the present application further includes a metal layer 40. Along the plane direction of the substrate 10, one end of the metal layer 40 is connected to the ground terminal 13, and the other end of the metal layer 40 is connected to the reflection grating 22 on at least one side of each interdigital transducer 21, so that the reflection grating 22 on at least one side of each interdigital transducer 21 is grounded. That is, the reflection grating 22 on at least one side of each interdigital transducer 21 is in a zero potential state.

[0083] In the related art, the reflection grating of the interdigital transducer is not grounded. At this time, the surface acoustic wave generated when the interdigital transducer works may interact with the reflection grating, causing an electric field to be generated on the reflection grating, and this part of the electric field will be coupled with the electric field generated when the interdigital transducer works, resulting in signal leakage. However, the filter 100 of the present application grounds the reflection grating 22 on at least one side of each interdigital transducer 21 through the metal layer 40 to ensure that the reflection grating 22 is at zero potential when the interdigital transducer 21 works. Thereby, the electric field generated on the reflection grating 22 is eliminated, the electric field coupling between the interdigital transducer 21 and the reflection grating 22 is eliminated, and signal leakage is reduced. Furthermore, the out-of-band rejection function and isolation of the filter 100 of the present application are improved.

[0084] In one embodiment, as Figure 4 and Figure 5 shown, the filter 100 of the present application further includes a plurality of parallel resonators 50, and the plurality of parallel resonators 50 are arranged at intervals on the surface of the substrate 10 and are spaced apart from the series resonator 20; wherein, one end of each parallel resonator 50 is electrically connected between any two adjacent series resonators 20, and the other end is grounded through the grounding terminal 13.

[0085] Each of the parallel resonators 50 is used to cooperate with the plurality of series resonators 20 to adjust the signal input from the signal input terminal 11, so as to further control the quality of the signal output via the signal output terminal 12. Thereby, the filtering function of the filter 100 of the present application is ensured.

[0086] In Figure 4 and Figure 5 the illustrated example, the number of series resonators 20 is four, and the number of parallel resonators 50 is four. Among them, two parallel resonators 50 are connected between two adjacent series resonators 20 close to the signal output terminal 12. It can be understood that in other embodiments, the number and connection manner of the series resonators 20 and the parallel resonators 50 can also be other, and the present application does not make special restrictions on this.

[0087] Please refer to Figure 7 another partial structural schematic diagram of the filter 100 provided in one embodiment of the present application shown.

[0088] In one embodiment, as Figure 7 shown, each parallel resonator 50 includes a second interdigital transducer 51 and second reflection gratings 52 located on both sides of the second interdigital transducer 51, and the arrangement directions of the second reflection gratings 52 on both sides of each parallel resonator 50 are parallel to the arrangement directions of the reflection gratings 22 on both sides of the series resonator 20.

[0089] Among them, the structure of the second interdigital transducer 51 of each parallel resonator 50 is similar to that of the interdigital transducer 21 of the series resonator 20. Specifically, as Figure 7 shown, each second interdigital transducer 51 includes a third bus bar 5111 and a fourth bus bar 5112 arranged in parallel and spaced apart, and a third electrode finger 5121 and a fourth electrode finger 5122 arranged in parallel and spaced apart.

[0090] The third electrode finger 5121 and the fourth electrode finger 5122 are located between the third bus bar 5111 and the fourth bus bar 5112. The third electrode finger 5121 and the fourth electrode finger 5122 are alternately arranged along the first direction 001. The third electrode finger 5121 and the fourth electrode finger 5122 both extend along the second direction 002. Specifically, as Figure 7 shown, along the first direction 001, there is a fourth electrode finger 5122 between any two adjacent third electrode fingers 5121, and there is a third electrode finger 5121 between any two adjacent fourth electrode fingers 5122.

[0091] In Figure 5 the illustrated example, the conducting layer 30 is also used to be electrically connected to the third bus bar 5111 of the parallel resonator 50. Thus, the parallel resonator 50 is conducted with the series resonator 20. At this time, the grounding terminal 13 is used to be electrically connected to the fourth bus bar 5112 of the parallel resonator 50, thereby realizing the grounding of the parallel resonator 50. That is, the parallel resonator 50 of the present application can be electrically connected between the connection line between any two adjacent series resonators 20 and the grounding terminal 13 through the third bus bar 5111 and the fourth bus bar 5112.

[0092] In the embodiment of the present application, the number of the second reflection gratings 52 is two. It can be understood that in some other embodiments, the number of the reflection gratings 52 can also be other, and the present application does not make special restrictions on this.

[0093] In one embodiment, the arrangement directions of the reflection gratings 22 of each series resonator 20 are parallel to each other, and the arrangement direction of the reflection grating 22 of any one series resonator 20 intersects with the arrangement directions of the plurality of series resonators 20. In Figure 5 the illustrated embodiment, the arrangement direction of the reflection grating 22 of each series resonator 20 is parallel to the arrangement directions of the respective electrode fingers 212 of the interdigital transducer 21. That is, the arrangement direction of the reflection grating 22 of each series resonator 20 is the first direction 001. The arrangement directions of the plurality of series resonators 20 are parallel to the arrangement direction of the bus bar 211 of each series resonator 20. That is, the arrangement directions of the plurality of series resonators 20 are the second direction 002.

[0094] It can be understood that, in some other embodiments, there is an included angle between the arrangement direction of the reflection grating 22 of each series resonator 20 and the first direction 001. There is also an included angle between the arrangement directions of the multiple series resonators 20 and the second direction 002. This application does not impose any special restrictions in this regard.

[0095] In one embodiment, as Figure 5 shown, the reflection gratings 22 on both sides of each series resonator 20 are electrically connected to the ground terminal 13 through the metal layer 40, so that each reflection grating 22 of each series resonator 20 is grounded. Thus, during the operation of the filter 100 of this application, it is ensured that each reflection grating 22 of each series resonator 20 is in a zero-potential state, thereby further improving the out-of-band rejection ability and isolation degree of the filter 100 of this application.

[0096] In some other embodiments, the reflection gratings 22 on both sides of some of the series resonators 20 among the various series resonators 20 are electrically connected to the ground terminal 13 through the metal layer 40. That is, among all the reflection gratings 22 of all the series resonators 20, there are some reflection gratings 22 that are not grounded.

[0097] In one embodiment, a series resonator 20 is electrically connected to a ground terminal 13. The series resonator 20 includes two reflection gratings 22. Along the first direction, the distances between the two reflection gratings 22 and the ground terminal 13 are different. The distance between one of the reflection gratings 22 and the ground terminal 13 is smaller, and this reflection grating is used for electrical connection to the ground terminal 13, while the other reflection grating 22 is not grounded. That is, the reflection grating 22 closer to the ground terminal 13 is electrically connected to the ground terminal 13 through the metal layer 40, reducing the space occupied by the metal layer 40, facilitating the miniaturization of the filter 100 of this application. At the same time, it can also reduce the wiring difficulty of the metal layer 40, facilitating the preparation of the filter 100 of this application.

[0098] In one embodiment, as Figure 5 shown, the number of ground terminals 13 is two, and the two ground terminals 13 are arranged at intervals along the arrangement direction of the reflection gratings 22 of the series resonator 20. Along the first direction 001, one of the terminals 13 is located at a position near the edge on the upper side of the substrate 10, and the other terminal 13 is located at a position near the edge on the lower side of the substrate 10. The reflection gratings 22 of each series resonator 20 are electrically connected to the ground terminal 13 on the same side.

[0099] That is, along the first direction 001, each reflection grating 22 located on the same side of the interdigital transducer 21 is electrically connected to the ground terminal 13 on the same side through the metal layer 40. In this way, by arranging the metal layer 40 near the reflection gratings 22 on the same side, the wiring size of the metal layer 40 on the substrate 10 can be reduced, thereby reducing the space occupied by the metal layer 40 and facilitating the miniaturization of the filter 100 of the present application. At the same time, the wiring difficulty of the metal layer 40 can also be reduced, facilitating the preparation of the filter 100 of the present application.

[0100] Based on the limitations of the above embodiments, out-of-band rejection is used to reflect the performance and stability of the system. In the embodiments of the present application. Figure 8 and Figure 9 is a comparison graph of the out-of-band rejection curves obtained by the filter 100 provided in an embodiment of the present application and the filter in the comparative example based on different frequencies. Among them, Figure 8 and Figure 9 The abscissa is the frequency in GHz, and the ordinate is the out-of-band rejection in dB.

[0101] For each embodiment and comparative example, the resonator includes a substrate, and four series resonators and four parallel resonators on the surface of the substrate. Among them, the substrate includes a signal input end, a signal output end, and a ground terminal. The four series resonators are connected in series between the signal input end and the signal output end. One end of each parallel resonator is electrically connected between any two adjacent series resonators, and the other end of each parallel resonator is electrically connected to the ground terminal. At least one parallel resonator is connected between any two adjacent series resonators, and two parallel resonators are connected between the two adjacent series resonators close to the signal output end. The number of ground terminals is two, and the two ground terminals are arranged on both sides of the series resonator along the arrangement direction of the reflection gratings of the series resonator.

[0102] In the embodiments of the present application, the number of both the embodiment and the comparative example is one. Among them, the schematic diagram of the topological structure corresponding to the comparative example is the same as that corresponding to the embodiment. Figure 4 Compared with the comparative example, each reflection grating 22 of each series resonator 20 in the embodiment is electrically connected to the ground terminal 13 through the metal layer 40.

[0103] Figure 8 is a comparison graph of the out-of-band rejection curves when the filters corresponding to the embodiment and the comparative example are working, Figure 9 is another comparison graph of the out-of-band rejection curves when the filters corresponding to the embodiment and the comparative example are working.

[0104] Among them, the present application can judge the out-of-band rejection ability of the embodiment and the comparative example by observing the size relationship of the curves within the area corresponding to the straight line in Figure 8 The present application can judge by observing Figure 9Judge the out-of-band rejection capabilities of the embodiments and comparative examples based on the magnitude relationship of the curves in the medium frequency range between 1 GHz and 3.6 GHz.

[0105] As Figure 8 and Figure 9 shown, the out-of-band rejection capability of the filter 100 corresponding to the embodiment is better than that of the filter corresponding to the comparative example. This is because the reflection grating 22 of the series resonator 20 in the filter 100 of the present application is electrically connected to the ground terminal 13, avoiding the influence of the electric field generated during the operation of the filter 100 on the electric field generated during the operation of the interdigital transducer 21, and improving the out-of-band rejection capability of the filter 100.

[0106] Isolation is used to reflect the overall performance and stability of the system. In the embodiments of the present application. Figure 10 This is a curve comparison diagram of the isolation obtained from different frequencies of the filter 100 provided in an embodiment of the present application and the filter in the comparative example. Among them, Figure 10 the abscissa is the frequency in GHz, and the ordinate is the isolation, and its unit is dB.

[0107] For each embodiment and comparative example, the corresponding filter structure is the same as that of the above embodiments and comparative examples. Figure 10 This is a curve comparison diagram of the isolation of the filters corresponding to the embodiments and comparative examples. Among them, the present application can judge the isolation of the embodiments and comparative examples by observing Figure 10 the magnitude relationship of the curves in the area corresponding to the straight line.

[0108] As Figure 10 can be seen, the isolation of the filter 100 corresponding to the embodiment is better than that of the filter corresponding to the comparative example. This is because the reflection grating 22 of the series resonator 20 in the filter 100 of the present application is electrically connected to the ground terminal 13, avoiding the influence of the electric field generated during the operation of the filter 100 on the electric field generated during the operation of the interdigital transducer 21, and improving the isolation of the filter 100.

[0109] Please refer to Figure 11 another structural schematic diagram of the filter 100 provided in an embodiment of the present application shown.

[0110] As Figure 11 shown, multiple reflection gratings 22 on one side of the interdigital transducer 21 are electrically connected to the ground terminal 13 through the metal layer 40. That is, along the first direction 001, each reflection grating 22 on one side of the interdigital transducer 21 is grounded, so that during the operation of the filter 100 of the present application, the reflection grating 22 on one side of each series resonator 20 is at zero potential. Thereby improving the out-of-band rejection capability and isolation of the filter 100 of the present application.

[0111] Please refer to Figure 12 Another structural schematic diagram of the filter 100 provided in an embodiment of the present application as shown.

[0112] As Figure 12 shown, along the arrangement direction of the reflection gratings 22 of the series resonator 20, each of the reflection gratings 22 on at least one side of the interdigital transducer 21 is electrically connected to the ground terminal 13 through a metal layer 40. That is, each grounded reflection grating 22 is electrically connected to the ground terminal 13 through a metal layer 40. Correspondingly, the number of the metal layers 40 is the same as the number of the grounded reflection gratings 22.

[0113] In the embodiment of the present application, by electrically connecting each reflection grating 22 to be grounded to the ground terminal 13 through a separate metal layer 40, the situation that the reflection grating 22 cannot be grounded due to the damage of the metal layer 40 is avoided. Thereby, the working stability of the filter 100 of the present application during the working process is ensured.

[0114] Please refer to Figure 13 A partial enlarged structural schematic diagram of the filter 100 provided in an embodiment of the present application as shown.

[0115] As Figure 13 shown, a plurality of series resonators 20 include at least two first series resonators 20a, the metal layer 40 includes a first metal layer 41, and the first series resonators 20a are electrically connected to the ground terminal 13 through the first metal layer 41; wherein, along the arrangement direction of the plurality of series resonators 20, at least two first series resonators 20a are located on the same side of the ground terminal 13, the first metal layer 41 extends towards the ground terminal 13, and is electrically connected to the reflection gratings 22 of at least two first series resonators 20a along the arrangement direction of the two reflection gratings 22 of the series resonator 20.

[0116] Specifically, in Figure 13 the illustrated example, the number of the first series resonators 20a is two. Along the second direction 002, the reflection gratings 22 of the two first series resonators 20a located on the same side of the ground terminal 13 are electrically connected to the ground terminal 13 through a first metal layer 41, so as to reduce the space of the substrate 10 occupied by the metal layer 40 while ensuring that the reflection gratings 22 of the first series resonators 20a are grounded, so as to facilitate the miniaturization of the filter 100 of the present application.

[0117] In one embodiment, as Figure 13As shown, along the arrangement direction of the reflection grating 22 of the series resonator 20, the first metal layer 41 is located on the side of the reflection grating 22 away from the interdigital transducer 21. That is, along the first direction 001, the first metal layer 41 is closer to the edge of the substrate 10 than the reflection grating 22, so as to avoid the first metal layer 41 affecting the arrangement of the series resonator 20 and the parallel resonator 50. Thus, while ensuring that the reflection grating 22 of the first series resonator 20a is grounded, the wiring difficulty of the first metal layer 41 is reduced, facilitating the manufacture of the filter 100 of the present application.

[0118] In one embodiment, please refer back to Figure 5 , the plurality of series resonators 20 further includes at least one second series resonator 20b. Along the arrangement direction of the plurality of series resonators 20, at least two first series resonators 20a and at least one second series resonator 20b are arranged at intervals in sequence; wherein, between adjacent first series resonator 20a and second series resonator 20b, the distance between the first series resonator 20a and a side wall 14 of the substrate 10 is less than the distance between the second series resonator 20b and the side wall 14, and the grounding terminal 13 is located between the second series resonator 20b and the side wall 14.

[0119] In Figure 5 the illustrated example, the number of the first series resonators 20a is two, and the number of the second series resonators 20b is two. Along the second direction 002, the two first series resonators 20a and the two second series resonators 20b are arranged at intervals in sequence. Along the first direction 001, the distance between the first series resonator 20a and the side wall 14 is less than the distance between the second series resonator 20b and the side wall 14. Along the first direction 001, the grounding terminal 13 is located between the second series resonator 20b and the side wall 14. Compared with the distance between the first series resonator 20a and the side wall 14, the distance between the second series resonator 20b and the side wall 14 is larger. The second series resonator 20b is used to avoid the grounding terminal 13, so that there is enough space between the second series resonator 20b and the side wall 14 to accommodate the grounding terminal 13. At the same time, the wiring difficulty of the metal layer 40 can also be reduced, facilitating the preparation of the filter 100 of the present application.

[0120] In one embodiment, along the arrangement direction of the plurality of series resonators 20, among any two adjacent first series resonators 20a, the distance between one first series resonator 20a and the side wall 14 is greater than the distance between the other first series resonator 20a and the side wall 14. The first series resonator 20a with a larger distance from the side wall 14 is closer to the grounding terminal 13. There is enough space between the first series resonator 20a close to the grounding terminal 13 and the side wall to accommodate the metal layer 40, so that the wiring of the metal layer 40 can be a straight line, reducing the wiring difficulty of the metal layer 40, improving the connection effect between the first series resonator 20a and the grounding terminal 13, optimizing the overall layout of the filter 100, and facilitating the preparation of the filter 100 of the present application.

[0121] In Figure 5 In the illustrated example, the series resonator 20 includes two first series resonators 20a. Along the second direction 002, the two first series resonators 20a are both on the same side of the grounding terminal 13. Along the first direction 001, the distance between the first series resonator 20a close to the grounding terminal 13 and the side wall 14 is greater than the distance between the first series resonator 20a far from the grounding terminal 13 and the side wall 14. There is enough space between the first series resonator 20a close to the grounding terminal 13 and the side wall to accommodate the metal layer 40, so that the wiring of the metal layer 40 can be a straight line, reducing the wiring difficulty of the metal layer 40, improving the connection effect between the first series resonator 20a and the grounding terminal 13, optimizing the overall layout of the filter 100, and facilitating the preparation of the filter 100 of the present application.

[0122] Please refer to Figure 14 Another partial enlarged structural schematic diagram of the filter 100 provided in one embodiment of the present application shown in the figure.

[0123] In one embodiment, as Figure 14 shown, the first metal layer 41 includes a connected extension section 411 and a connection section 412. The extension section 411 extends towards the grounding terminal 13 along the arrangement direction of the plurality of series resonators 20, and the connection section 412 extends towards the reflection grating 22. The extension section 411 is electrically connected to the grounding terminal 13, and the reflection grating 22 of at least one first series resonator 20a is electrically connected to the extension section 411 through the connection section 412.

[0124] Specifically, in Figure 14In the illustrated legend, along the second direction 002, two first series resonators 20a are located on the same side of the ground terminal 13. An extension section 411 is provided between the first series resonator 20a far from the ground terminal 13 and the side wall 14. One end of the extension section 411 is electrically connected to the reflection grating 22 of the first series resonator 20a, and the other end extends along the first direction 001 towards the ground terminal 13 and is electrically connected to the ground terminal 13. That is, the reflection grating 22 of the first series resonator 20a far from the ground terminal 13 is electrically connected to the ground terminal 13 through the extension section 411. In the embodiment of the present application, when the extension section 411 is connected to the reflection grating 22 of the corresponding resonator, the end of the extension section 411 can be connected to any side of the reflection grating 22. For details, see Figure 14 In [reference], the extension section 411 is connected to the side wall of the reflection grating 22 near the edge of the substrate 10.

[0125] Along the first direction 001, the first series resonator 20a close to the ground terminal 13 is spaced from the extension section 411. The first metal layer 41 includes a connection section 412. One end of the connection section 412 is electrically connected to the extension section 411, and the other end extends along the second direction 002 towards the first series resonator 20a close to the ground terminal 13. The connection section 412 is used to conduct the reflection grating 22 of the first series resonator 20a and the extension section 411. That is, the reflection grating 22 of the first series resonator 20a close to the ground terminal 13 is electrically connected through the connection section 412 and the extension section 411.

[0126] The extension section 411 and the connection section 412 can conduct the reflection gratings 22 of the first series resonators 20a at different positions and the ground terminal 13, so that the first series resonators 20a can be arranged at more positions, facilitating the arrangement of multiple first series resonators 20a on the substrate 10. At the same time, the two first series resonators 20a are electrically connected to the ground terminal 13 through a first metal layer 41, reducing the occupied space of the first metal layer 41 and facilitating the miniaturization of the filter 100 of the present application. In addition, along the first direction 001, the extension section 411 is located above the reflection grating 22, that is, the extension section 411 is located on the side of the reflection grating 22 away from the interdigital transducer 21. The extension section 411 can block and reflect sound waves, improving the isolation of the filter 100.

[0127] In one embodiment, as Figure 14 shown, the connection section 412 is electrically connected to the reflection grating 22 through at least one contact point 4121.

[0128] In one embodiment, the width of the connecting segment 412 towards one end of the reflection grating 22 is greater than the width at other positions of the connecting segment 412. That is, the connecting segment 412 has a larger contact area with the reflection grating 22, improving the connection effect between the connecting segment 412 and the reflection grating 22 and ensuring the stability of the connection between the connecting segment 412 and the reflection grating 22.

[0129] Please refer to Figure 15 Another partial enlarged structural schematic diagram of the filter 100 provided in one embodiment of the present application shown in the figure.

[0130] In one embodiment, as Figure 15 shown, the number of contact points 4121 is multiple, and the multiple contact points 4121 are arranged at intervals along the arrangement direction of the multiple series resonators 20.

[0131] Specifically, in the Figure 15 shown example, the connecting segment 412 includes multiple connecting sub-segments 4122. One end of each connecting sub-segment 4122 is electrically connected to the extending segment 411, and the other end extends along the first direction 001 towards the reflection grating 22 of the first series resonator 20a and contacts it to form a contact point 4121. The multiple connecting sub-segments 4122 are arranged at intervals along the second direction 002, so that the multiple contact points 4121 are also arranged at intervals along the second direction 002. Compared with the connecting segment 412 being electrically connected to the reflection grating 22 of the first series resonator 20a through a single contact point 4121, the multiple contact points 4121 can improve the reliability of the electrical connection between the first metal layer 41 and the first series resonator 20a, and further ensure the electrical connection between the reflection grating 22 of the first series resonator 20a and the ground terminal 13.

[0132] In one embodiment, the distance between any two adjacent contact points 4121 of any connecting segment 412 is equal, and the width of each contact point 4121 is less than or equal to the width of the extending segment 411.

[0133] Please refer to Figure 15 shown, the distance between any two adjacent connecting sub-segments 4122 is equal, so that the distance between any two adjacent contact points 4121 is equal. The widths of the respective connecting sub-segments 4122 are equal and are respectively less than the width of the extending segment 411, reducing the overall space occupied by the connecting segment 412 and facilitating the miniaturization of the filter 100. At the same time, on the premise of ensuring the reliable connection between the connecting segment 412 and the reflection grating 22, the materials required for the connecting segment 412 are reduced, and the cost of the filter 100 is reduced.

[0134] Please refer to Figure 16 Another partial enlarged structural schematic diagram of the filter 100 provided in one embodiment of the present application shown in the figure.

[0135] In one embodiment, as Figure 16 shown, the dimension of the connecting section 412 along the second direction 002 is greater than the dimension of the connecting section 412 along the first direction 001, so that there is a large contact area between the connecting section 412 and the reflection grating 22, improving the connection effect between the connecting section 412 and the reflection grating 22 and the stability of the connection between the connecting section 412 and the reflection grating 22.

[0136] In one embodiment, as Figure 16 shown, the connecting section 412 includes at least one hollow 4123, and the hollow 4123 is used to reduce the mass of the connecting section 412 on the premise of ensuring the connection effect between the reflection grating 22 and the extension section 411, facilitating the lightweight of the filter 100.

[0137] In one embodiment, as Figure 5 shown, along the arrangement direction of the reflection gratings 22 of the series resonator 20, the distance between two first series resonators 20a is less than or equal to 20 μm. That is, the distance between two reflection gratings 22 on the same side of two first series resonators 20a is less than or equal to 20 μm, so as to limit the overall dimension of the first series resonator 20a along the first direction 001, reduce the occupied space of the first series resonator 20a, and facilitate the miniaturization of the filter. At the same time, by limiting the maximum distance between two first series resonators 20a along the first direction 001, the length dimension of the connecting section 412 is reduced, and the cost of the filter 100 is reduced. Optionally, the distance between two first series resonators 20a is set to 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm.

[0138] In one embodiment, along the arrangement direction of the reflection gratings 22 of the series resonator 20, the distance between two first series resonators 20a is greater than or equal to 5 μm and less than or equal to 8 μm. That is, the distance between two reflection gratings 22 on the same side of two first series resonators 20a is greater than or equal to 5 μm and less than or equal to 8 μm, so that the overall dimension of the first series resonator 20a along the first direction 001 is small, and the maximum distance between two first series resonators 20a along the first direction 001 is small, which also facilitates the miniaturization of the filter 100 and reduces the cost of the filter 100. Optionally, the distance between two first series resonators 20a is set to 5 μm, 6 μm, 7 μm, 8 μm.

[0139] Please refer to Figure 17 the schematic cross-sectional structure diagram of a filter 100 provided in one embodiment of the present application shown.

[0140] In one embodiment, as Figure 17As shown, the metal layer 40 is located on the surface of the substrate 10, and the metal layer 40 extends toward the ground terminal 13 in the plane direction of the substrate 10. Along the direction perpendicular to the extension direction of the metal layer 40, the width of the metal layer 40 is greater than or equal to 0.3 μm. By restricting the minimum width dimension of the metal layer 40, the metal layer 40 has higher reliability, thereby improving the reliability of the electrical connection between the reflection grating 22 of the series resonator 20 and the ground terminal 13. Optionally, the width of the metal layer 40 is set to 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 5 μm.

[0141] In one embodiment, the metal layer 40 and the reflection grating 22 are provided on the same layer. The metal layer 40 and the reflection grating 22 provided on the same layer have a large contact area, which is beneficial to realizing the electrical connection between the reflection grating 22 of the series resonator 20 and the metal layer 40. The metal layer 40 and the reflection grating 22 can be prepared by the same process, simplifying the manufacturing process of the filter 100 and improving the manufacturing efficiency of the filter 100.

[0142] In one embodiment, the width of the metal layer 40 is greater than or equal to 1 μm and less than or equal to 5 μm. By restricting the width dimension of the metal layer 40, while ensuring the reliable electrical connection between the metal layer 40 and the reflection grating 22 of the series resonator 20, the space occupied by the metal layer 40 is reduced, facilitating the miniaturization of the filter 100. At the same time, the material required for the metal layer 40 is reduced, lowering the cost of the filter 100. Optionally, the width of the metal layer 40 is set to 1 μm, 2 μm, 3 μm, 5 μm.

[0143] In one embodiment, the material of the metal layer 40 includes at least one of aluminum, copper, titanium, chromium, gold, and silver. The metal layer 40 made of the above materials has good electrical conductivity, which is beneficial to realizing the electrical connection between the reflection grating 22 of the series resonator 20 and the ground terminal 13. Among them, the connection section 412 and other parts of the metal layer 40 can be made of the same or different materials.

[0144] In one embodiment, the connection section 412 is made of a different material from that of the metal layer 40, and the hardness of the material of the connection section 412 is less than the hardness of the material of other parts of the metal layer 40, facilitating the forming of the connection section 412 and improving the manufacturing efficiency of the filter 100.

[0145] Please refer to Figure 18 Another cross-sectional structure schematic diagram of the filter 100 provided in an embodiment of the present application as shown.

[0146] In one embodiment, as Figure 18As shown, the metal layer 40 is embedded in the substrate 10, and the metal layer 40 is used to form part of the surface of the substrate 10. The projections of the reflection grating 22 of the series resonator 20 and the ground terminal 13 on the substrate 10 are located within the metal layer 40. The metal layer 40 is respectively in contact with the reflection grating 22 and the ground terminal 13, so that the reflection grating 22 is electrically connected to the ground terminal 13. Embedding the metal layer 40 in the substrate 10 can save the space on the surface of the substrate 10, improve the space utilization rate of the filter 100, and facilitate the miniaturization of the filter 100.

[0147] In one embodiment, the metal layer 40 and the parallel resonator 50 are spaced apart from each other, and the distance between the metal layer 40 and the parallel resonator 50 is greater than or equal to 0.3 μm. By restricting the distance between the metal layer 40 and the parallel resonator 50, it is avoided that the parallel resonator 50 is electrically connected to the metal layer 40 and affects the normal operation of the parallel resonator 50.

[0148] It should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second" may explicitly or implicitly include one or more features. In the description of the embodiments of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0149] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0150] It should be understood that the application of the present application is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present application. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A filter, characterized in that, Comprising a substrate, and a plurality of series resonators arranged at intervals on the substrate, the substrate includes a signal input terminal, a signal output terminal, and a ground terminal, the signal input terminal is used to receive an external signal, the signal output terminal is used to output a signal, and the plurality of series resonators are connected in series between the signal input terminal and the signal output terminal in sequence; wherein, Each of the series resonators includes an interdigital transducer and reflection gratings located on both sides of the interdigital transducer, and the reflection gratings on at least one side of each interdigital transducer are electrically connected to the ground terminal through a metal layer.

2. The filter according to claim 1, characterized in that, The arrangement directions of the reflection gratings of each of the series resonators are parallel to each other, and the arrangement direction of the reflection gratings of any one of the series resonators intersects with the arrangement direction of the plurality of series resonators.

3. The filter according to claim 2, characterized in that The reflection gratings on both sides of at least some of the series resonators are electrically connected to the ground terminal through the metal layer.

4. The filter according to claim 3, wherein, The number of the ground terminals is two, and the two ground terminals are arranged at intervals along the arrangement direction of the reflection gratings of the series resonators, and the reflection gratings of the at least some series resonators are respectively electrically connected to the ground terminal on the same side.

5. The filter according to claim 2, wherein A plurality of the reflection gratings on one side of the interdigital transducer are electrically connected to the ground terminal through the metal layer.

6. The filter according to any one of claims 1-5, characterized in that, Along the arrangement direction of the reflection gratings of the series resonators, each of the reflection gratings on at least one side of the interdigital transducer is respectively electrically connected to the ground terminal through a metal layer.

7. The filter according to any one of claims 1-5, characterized in that, The plurality of series resonators include at least two first series resonators, the metal layer includes a first metal layer, and the first series resonators are electrically connected to the ground terminal through the first metal layer; Wherein, along the arrangement direction of the plurality of series resonators, the at least two first series resonators are located on the same side of the ground terminal, the first metal layer extends towards the ground terminal, and along the arrangement direction of the two reflection gratings of the series resonators, it is electrically connected to the reflection gratings of the at least two first series resonators.

8. The filter according to claim 7, wherein Along the arrangement direction of the reflection gratings of the series resonators, the first metal layer is located on the side of the reflection grating away from the interdigital transducer.

9. The filter according to claim 7, characterized in that, The plurality of series resonators further include at least one second series resonator, and along the arrangement direction of the plurality of series resonators, the at least two first series resonators and the at least one second series resonator are arranged at intervals in sequence; wherein, Among adjacent first series resonators and second series resonators, the distance between the first series resonator and a side wall of the substrate is less than the distance between the second series resonator and the side wall, and the ground terminal is located between the second series resonator and the side wall.

10. The filter according to claim 9, characterized in that, Along the arrangement direction of the plurality of series resonators, among any two adjacent first series resonators, the distance between one first series resonator and the side wall is greater than the distance between the other first series resonator and the side wall, and the first series resonator with a larger distance from the side wall is closer to the ground terminal.

11. The filter according to claim 7, wherein The first metal layer includes an extending section and a connecting section connected to each other. The extending section extends toward the grounding terminal along the arrangement direction of the plurality of series resonators, and the connecting section extends toward the reflection grating. Wherein, the extending section is electrically connected to the grounding terminal, and the reflection grating of at least one of the first series resonators is electrically connected to the extending section through the connecting section.

12. The filter according to claim 11, wherein The connecting section is electrically connected to the reflection grating through at least one contact point.

13. The filter according to claim 12, wherein The number of the contact points is multiple, and the multiple contact points are arranged at intervals along the arrangement direction of the plurality of series resonators.

14. The filter according to claim 13, wherein The distance between any two adjacent contact points of any one of the connecting sections is equal, and the width of each contact point is less than or equal to the width of the extending section.

15. The filter according to any one of claims 1-5, characterized in that, The material of the metal layer includes at least one of aluminum, copper, titanium, chromium, gold and silver.

16. The filter according to any one of claims 1-5, characterized in that, The metal layer is located on the surface of the substrate, and the metal layer extends toward the grounding terminal along the plane direction of the substrate; wherein, Along the direction perpendicular to the extending direction of the metal layer, the width of the metal layer is greater than or equal to 0.3 μm.

17. The filter according to claim 16, wherein The metal layer is arranged on the same layer as the reflection grating.

18. The filter according to claim 16, wherein The width of the metal layer is greater than or equal to 1 μm and less than or equal to 5 μm.

19. The filter according to any one of claims 1-5, characterized in that, Along the arrangement direction of the two reflection gratings of the series resonator, the metal layer is connected to the side of the reflection grating away from the interdigital transducer.

20. The filter according to any one of claims 1-5, characterized in that, The filter further includes a plurality of parallel resonators, and the plurality of parallel resonators are arranged at intervals on the surface of the substrate and are spaced apart from the series resonators; wherein, One end of each parallel resonator is electrically connected between any two adjacent series resonators, and the other end is grounded through the grounding terminal.

21. The filter according to claim 20, wherein The metal layer is spaced apart from the parallel resonator, and the distance between the metal layer and the parallel resonator is greater than or equal to 0.3 μm.

22. The filter according to claim 20, wherein Each parallel resonator includes a second interdigital transducer and second reflection gratings located on both sides of the second interdigital transducer, and the arrangement directions of the second reflection gratings on both sides of each parallel resonator are parallel to the arrangement directions of the reflection gratings on both sides of the series resonator.

23. A multiplexer, characterized in that, At least includes a transmitting filter and a receiving filter; The transmitting filter includes the filter according to any one of claims 1-22; and / or, The receiving filter includes the filter according to any one of claims 1-22.

24. A radio frequency front-end module, characterized in that, Includes the multiplexer according to claim 23.

25. An electronic device, characterized in that, Includes the radio frequency front-end module according to claim 24.

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