Filter and radio frequency front-end module

Abstract

The utility model provides a filter and a radio frequency front-end module, and the filter comprises a plurality of resonance modules, and each resonance module comprises at least one series arm resonator group and at least one parallel arm resonator group. The plurality of resonance modules comprise a first resonance module, the first resonance module is connected with the output end of the filter, and the first resonance module is located at the tail end of a signal circulation path of the filter; the resonant frequency of at least one parallel arm resonator group in the first resonant module is configured between the first frequency and the second frequency; wherein the first frequency is two times smaller than the center frequency of the filter, and the second frequency is three times larger than the center frequency of the filter. The utility model aims to effectively weaken the nonlinear distortion intensity generated by the filter.

Description

Technical Field

[0001] The present application relates to the technical field of radio frequency filtering, and in particular to a filter and a radio frequency front-end module. Background Art

[0002] Filters are commonly used electronic components in radio frequency circuits, used to filter out signals of specific frequencies or frequencies outside of them. Resonators are the basic building blocks of filters. When high input power is applied to a filter, the resonators within the filter are subjected to the high power. This high power generates some nonlinear distortion, which, if not suppressed, can have a destructive impact on the system. Therefore, effectively reducing the intensity of this nonlinear distortion has become a pressing issue. Utility Model Content

[0003] The main purpose of this application is to provide a filter and a radio frequency front-end module, aiming to solve the problem of how to effectively reduce the intensity of nonlinear distortion generated by the filter.

[0004] In a first aspect, the present application provides a filter, comprising a plurality of resonant modules, each of the resonant modules comprising at least one series arm resonator group and at least one parallel arm resonator group; each of the series arm resonator groups is connected in series between an input end and an output end of the filter, and each of the parallel arm resonator groups is connected between one end of the series arm resonator group in the same resonant module and a ground end;

[0005] The multiple resonance modules include a first resonance module, which is connected to the output end of the filter and is located at the end of the signal flow path of the filter; the resonant frequency of at least one of the parallel arm resonator groups in the first resonance module is configured between a first frequency and a second frequency; wherein the first frequency is less than 2 times the center frequency of the filter, and the second frequency is greater than 3 times the center frequency of the filter.

[0006] In a second aspect, the present application further provides a filter, comprising a plurality of resonant modules, each of the resonant modules comprising at least one series arm resonator group and at least one parallel arm resonator group; each of the series arm resonator groups is connected in series between an input end and an output end of the filter, and each of the parallel arm resonator groups is connected between one end of the series arm resonator group in the same resonant module and a ground end;

[0007] The plurality of resonance modules include a first resonance module, the first resonance module is connected to the output end of the filter, and the first resonance module is located at the end of the signal flow path of the filter;

[0008] The series arm resonator group in the first resonant module includes an even number of first resonators, the even number of first resonators are connected in series and have the same resonant frequency; in the series path, the electric fields of two adjacent first resonators are in opposite directions; and / or,

[0009] The parallel arm resonator group in the first resonance module includes an even number of second resonators, which are connected in series and have the same resonance frequency; in the series path, the electric fields of two adjacent second resonators are in opposite directions.

[0010] In a third aspect, an embodiment of the present application further provides a radio frequency front-end module, comprising a filter as described in any one of the embodiments of the present application.

[0011] The present application provides a filter and a radio frequency front-end module, wherein the filter includes a plurality of resonant modules, each of which includes at least one series arm resonator group and at least one parallel arm resonator group. The plurality of resonant modules include a first resonant module, which is connected to the output end of the filter and is located at the end of the signal flow path of the filter; the resonant frequency of at least one parallel arm resonator group in the first resonant module is configured between a first frequency and a second frequency; wherein the first frequency is less than 2 times the center frequency of the filter, and the second frequency is greater than 3 times the center frequency of the filter. Setting the resonant frequency of the parallel arm resonator group in the first resonant module at the end of the signal flow path to be near 2 times to 3 times the center frequency can effectively suppress the signal component with a frequency between 2f0 and 3f0 generated at the front end of the first resonant module, thereby suppressing the nonlinear distortion generated by the resonant module at the front end of the signal flow path, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0013] Figure 1 A circuit diagram of an embodiment of a filter provided in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of the scattering parameters of the filter provided in an embodiment of the present application;

[0015] Figure 3 A schematic diagram of a filter nonlinearity test item provided in an embodiment of the present application;

[0016] Figure 4A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0017] Figure 5 A schematic diagram of the connection of the first resonator of the filter provided in an embodiment of the present application;

[0018] Figure 6 A schematic diagram of the connection of the second resonator of the filter provided in an embodiment of the present application;

[0019] Figure 7 Another schematic diagram of a filter nonlinearity test item provided in an embodiment of the present application;

[0020] Figure 8 A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0021] Figure 9 A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0022] Figure 10 A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0023] Figure 11 A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0024] Figure 12 A circuit diagram of another embodiment of the filter provided in the embodiment of the present application;

[0025] Figure 13 Another schematic diagram of a filter nonlinearity test item provided in an embodiment of the present application;

[0026] Figure 14 A circuit diagram of an implementation of another filter provided in an embodiment of the present application;

[0027] Figure 15 A circuit diagram of another embodiment of another filter provided in an embodiment of the present application;

[0028] Figure 16 A schematic diagram of the RF front-end module provided in an embodiment of the present application.

[0029] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0032] Please refer to Figure 1 , Figure 1 This is a circuit diagram of an implementation of a filter provided in an embodiment of the present application.

[0033] like Figure 1 As shown, the filter 100 includes a plurality of resonant modules, which include, for example, a first resonant module 110 and a plurality of other resonant modules 120. Each resonant module includes at least one series arm resonator group and at least one parallel arm resonator group, the series arm resonator groups are, for example, S1, S2, S3 and S4, and the parallel arm resonator groups are, for example, P1, P2, P3 and P4. Each series arm resonator group is connected in series between the input and output ends of the filter 100, and each parallel arm resonator group is connected between one end of the series arm resonator group in the same resonant module and the ground end. For example, the series arm resonator groups S1, S2, S3 and S4 are connected in series between the input and output ends of the filter 100, and the parallel arm resonator groups P1, P2, P3 and P4 are respectively connected between one end of the series arm resonator groups S1, S2, S3 and S4 and the ground end.

[0034] The filter 100 can be applied to either a transmitting circuit or a receiving circuit. When the filter 100 is configured in a transmitting circuit, the input terminal of the filter 100 serves as the internal interface of the transmitting circuit, and the output terminal of the filter 100 is connected to the antenna interface of the transmitting circuit. When the filter 100 is configured in a receiving circuit, the input terminal of the filter 100 is connected to the antenna interface of the transmitting circuit, and the output terminal of the filter 100 serves as the internal interface of the transmitting circuit.

[0035] It should be noted that Figure 1 For illustration, it is taken that the plurality of resonance modules in the filter 100 include a first resonance module 110 and a plurality of other resonance modules 120 . In actual applications, the filter 100 may include a smaller or larger number of resonance modules. Figure 1In the example of each resonant module including one series arm resonator group and one parallel arm resonator group, the number of series arm resonator groups and parallel arm resonator groups in the resonant module in actual applications can be two or more. Moreover, the number of series arm resonator groups and parallel arm resonator groups in each resonant module can be the same or different. For example, a resonant module can include one series arm resonator group and two parallel arm resonator groups.

[0036] The series arm resonator groups and parallel arm resonator groups in multiple resonant modules can form a cascade circuit. Figure 1 The series arm resonator groups S1, S2, S3 and S4 and the parallel arm resonator groups P1, P2, P3 and P4 in the cascade circuit form a cascade circuit, thereby filtering out specific frequencies in the signal or signals other than specific frequencies. One end of the parallel arm resonator group can be connected to the input end of the series arm resonator group in the same resonant module, or it can be connected to the output end of the series arm resonator group in the same resonant module. For example, the parallel arm resonator group P1 can be connected to one end of the series arm resonator group S1, or it can be connected to the other end of the series arm resonator group S1. The other end of the parallel arm resonator group is connected to the ground terminal, which can be set one by one according to each parallel arm resonator group, or it can be grouped according to the number of two or more parallel arm resonator groups. When grouped, at least two parallel arm resonator groups in each group are connected to a ground terminal. For example, the parallel arm resonator groups P1 and P2 can be connected to the same ground terminal.

[0037] Furthermore, the series arm resonator group may include at least one resonator, and each resonator in each series arm resonator group is connected in series between the input terminal input and the output terminal Output of the filter 100. In addition, the parallel arm resonator group may include at least one resonator, and each resonator in each parallel arm resonator group is connected between one end of the series arm resonator group in the same resonant module and the ground terminal. Each series arm resonator group and each parallel arm resonator group may be arranged as an integral whole. For example, in each series arm resonator group and each parallel arm resonator group, the interdigital transducers of two or more resonators may be arranged on the same piezoelectric substrate.

[0038] like Figure 1 As shown, the multiple resonant modules include a first resonant module 110, which is connected to the output terminal Output of the filter 100 and is located at the end of the signal flow path of the filter 100. The resonant frequency of at least one parallel arm resonator group (such as P1) in the first resonant module 110 is configured between a first frequency and a second frequency. The first frequency is less than 2 times the center frequency of the filter 100, and the second frequency is greater than 3 times the center frequency of the filter 100.

[0039] Among them, the first resonant module 110 can be the final resonant module at the end of the signal flow among the multiple resonant modules of the filter 100. For example, when the filter 100 is applicable to the transmitting circuit, the first resonant module 110 can be connected to the antenna interface of the transmitting circuit as the final resonant module. When the filter 100 is applicable to the receiving circuit, the first resonant module 110 can be connected to the internal interface of the transmitting circuit as the final resonant module. The center frequency of the filter 100 may refer to the center frequency of the passband of the filter 100. The resonant frequency of each series arm resonator (such as S1) in the first resonant module 110 can be set based on actual conditions.

[0040] It should be noted that the first frequency can be set to 1.8-1.99 times f0, and the second frequency can be set to 3.01-3.2 times f0, where f0 represents the center frequency of the filter 100. For example, the first frequency is 1.8 times f0, and the second frequency is 3.2 times f0. The resonant frequency of the parallel arm resonator group (such as P1) in the first resonant module 110 is configured between the first frequency and the second frequency, that is, the resonant frequency of the parallel arm resonator group (such as P1) in the first resonant module 110 is set near the 2nd and 3rd frequencies of the filter 100, so that the nonlinear distortion generated by the other resonant modules 120 before the first resonant module 110 can be suppressed, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter 100.

[0041] For example, Figure 2 As shown, Figure 2 A schematic diagram of the scattering parameters of the filter provided in an embodiment of the present application. Because filter 100 has a strong suppression effect on the input signal at 2*f0 and 3*f0, configuring the resonant frequency of the parallel arm resonator group in the first resonant module 110 near 2 times f0 and 3 times f0 reduces the intensity of the nonlinear distortion generated by the filter to a certain extent.

[0042] For example, Figure 3 As shown, the resonant frequency of the parallel arm resonator group P1 in the first resonant module 110 is configured between the first frequency and the second frequency, and a 29dBm CW wave (continuous wave) is loaded to the input of the filter 100. The power of the quadratic nonlinear term H2 in the passband is measured to be below -50dBm, and the power of the cubic nonlinear term H3 in the passband is below -40dBm. Obviously, the intensity of the nonlinear distortion generated by the filter 100 is effectively reduced.

[0043] It should be noted that there may be multiple parallel arm resonator groups in the first resonant module 110. When the first resonant module 110 includes multiple parallel arm resonator groups, the resonant frequencies of one or more parallel arm resonator groups are configured between the first frequency and the second frequency. Of course, the resonant frequencies of all parallel arm resonator groups in the first resonant module 110 may also be configured between the first frequency and the second frequency.

[0044] Exemplarily, the first resonance module 110 includes a first parallel arm resonator group and a second parallel arm resonator group, which are connected in parallel. In the embodiment of the present application, the resonant frequency of the first parallel arm resonator group or the second parallel arm resonator group can be configured between the first frequency and the second frequency, or the resonant frequency of the first parallel arm resonator group and the second parallel arm resonator group can be configured between the first frequency and the second frequency.

[0045] In one embodiment, the resonant frequency of at least one series arm resonator group (e.g., S1) in the first resonant module 110 is configured between a third frequency and a fourth frequency, wherein the third frequency is less than the center frequency of the filter 100, and the fourth frequency is greater than the center frequency of the filter 100. For example, the third frequency is 0.9 times f0, and the second frequency is 1.1 times f0, where f0 is the center frequency of the filter 100.

[0046] It should be noted that there may be multiple series arm resonator groups in the first resonant module 110. When the first resonant module 110 includes multiple series arm resonator groups, the resonant frequencies of one or more series arm resonator groups are configured between the third frequency and the fourth frequency. Of course, the resonant frequencies of all series arm resonator groups in the first resonant module 110 may also be configured between the third frequency and the fourth frequency.

[0047] Exemplarily, the first resonant module 110 includes a first series arm resonator group and a second series arm resonator group, which are connected in parallel. In the embodiment of the present application, the resonant frequency of the first series arm resonator group or the second series arm resonator group can be configured between the third frequency and the fourth frequency, or the resonant frequency of the first series arm resonator group and the second series arm resonator group can be configured between the third frequency and the fourth frequency.

[0048] In one embodiment, the resonant frequency of at least one parallel arm resonator group (such as P1) in the first resonant module 110 is configured to be within a first frequency band or a second frequency band, wherein the first frequency band is centered at 2 times the center frequency of the filter 100, and the second frequency band is centered at 3 times the center frequency of the filter 100. Both the first frequency band and the second frequency band are within a frequency range from the first frequency to the second frequency. For example, the first frequency band includes 1.8 times f0 to 2.2 times f0, and the second frequency band includes 2.8 times f0 to 3.2 times f0, where f0 represents the center frequency of the filter 100.

[0049] For example, Figure 2 and Figure 3 As shown, the resonant frequency of the parallel arm resonator group P1 in the first resonant module 110 can be further configured within a first frequency band centered on 2f0, or the resonant frequency of the parallel arm resonator group P1 in the first resonant module 110 can be configured within a second frequency band centered on 3f0, so that the nonlinear distortion generated by other resonant modules 120 before the first resonant module 110 can be suppressed, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter 100.

[0050] In one embodiment, the series-arm resonator group in the first resonant module 110 includes an even number of first resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent first resonators are directed in opposite directions. The even number is, for example, 2N, such as 2, 4, 6, or the like, where N is a positive integer.

[0051] Taking the case where the number of cascades is 2 as an example, Figure 4 The series arm resonator group S1 shown includes a first resonator S1-1 and a first resonator S1-2. The first resonator S1-1 and the first resonator S1-2 are connected in series and have the same resonant frequency. The electric field directions of the adjacent first resonators S1-1 and S1-2 are opposite, wherein the electric field direction of the first resonator S1-1 is e S1-1 is the first direction, and the electric field direction e of the first resonator S1-2 is S1-2 The first direction is the second direction, and the first direction and the second direction are arranged opposite to each other.

[0052] It should be noted that since the first resonance module 110 itself will also generate nonlinear distortion, the series arm resonator group (such as S1) in the first resonance module 110 can be configured as an even number of first resonators (such as S1-1 and S1-2). The resonant frequencies of the even number of first resonators are the same, and the electric field directions of the two adjacent first resonators (such as S1-1 and S1-2) are opposite. Therefore, the nonlinear distortion of the first resonance module 110 itself can be weakened by canceling the nonlinear terms of the resonators, thereby further weakening the intensity of the nonlinear distortion generated by the filter 100 as a whole.

[0053] That is, through this embodiment, not only the nonlinear signals generated by the other resonance modules 120 except the first resonance module 110 can be weakened, but also the nonlinear signals generated by the first resonance module 110 itself can be weakened.

[0054] Furthermore, the region defined by two adjacent electrode fingers of any first resonator in the series-arm resonator group is used as the first region, and the region defined by two adjacent electrode fingers of an adjacent first resonator of the first resonator is used as the second region. The two adjacent electrodes of the first resonator and the adjacent first resonator can be symmetrically arranged and have opposite electrical polarities. Therefore, the electric field direction of the two adjacent electrode fingers in the first region can be opposite to the electric field direction of the two adjacent electrode fingers in the second region.

[0055] like Figure 4 and Figure 5 As shown, the first resonator S1-1 and the first resonator S1-2 in the series-arm resonator group S1 are connected in series. The two adjacent electrode fingers in the first resonator S1-1 include electrode finger 101 and electrode finger 102, and the two adjacent electrode fingers in the first resonator S1-2 include electrode finger 103 and electrode finger 104. Electrode finger 101 has a positive electrical polarity in the first resonator S1-2, while the symmetrical electrode finger 104 has a negative electrical polarity in the first resonator S1-1. The electric field direction in a first region between electrode finger 101 and electrode finger 102 is a first direction. Electrode finger 102 has a negative electrical polarity in the first resonator S1-2, while the symmetrical electrode finger 103 has a positive electrical polarity in the first resonator S1-1. The electric field direction in a second region between electrode finger 103 and electrode finger 104 is a second direction, which is opposite to the first direction.

[0056] In one embodiment, the parallel arm resonator group in the first resonant module 110 includes an even number of second resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent second resonators have opposite directions.

[0057] for example, Figure 4 The parallel arm resonator group P1 shown includes a second resonator P1-1 and a second resonator P1-2. The second resonator P1-1 and the second resonator P1-2 are connected in series and have the same resonant frequency. The electric field directions of the adjacent second resonators P1-1 and P1-2 are opposite, wherein the electric field direction of the second resonator P1-1 is e P1-1 The electric field direction of the second resonator P1-2 is e P1-2 The third direction is opposite to the fourth direction.

[0058] It should be noted that by configuring the parallel arm resonator group in the first resonant module 110 as an even number of second resonators, the resonant frequencies of the even number of second resonators are the same and the electric field directions of two adjacent second resonators are opposite. Therefore, the nonlinear distortion of the first resonant module 110 itself can be weakened by canceling the nonlinear terms of the resonators, thereby further suppressing the nonlinear distortion generated by the filter 100 as a whole.

[0059] That is to say, by setting an even number of second resonators connected in series with the same resonant frequency, and the electric field directions of two adjacent second resonators in the series path are opposite, the nonlinear signals generated by the other resonant modules 120 except the first resonant module 110 can be weakened, and the nonlinear signals generated by the first resonant module 110 itself can also be weakened.

[0060] Furthermore, the region defined by two adjacent electrode fingers of any second resonator in the series-arm resonator group serves as the third region, and the region defined by two adjacent electrode fingers of the second resonator adjacent to the second resonator serves as the fourth region. The two adjacent electrodes of the second resonator and the adjacent second resonator may be symmetrically arranged and have opposite electrical polarities. Therefore, the direction of current flowing through the two adjacent electrode fingers in the third region may be opposite to the direction of the electric field flowing through the two adjacent electrode fingers in the fourth region.

[0061] like Figure 4 and Figure 6 As shown, the second resonator P1-1 and the second resonator P1-2 in the series-arm resonator group P1 are connected in series. The two adjacent electrode fingers in the second resonator P1-1 include electrode finger 201 and electrode finger 202, and the two adjacent electrode fingers in the second resonator P1-2 include electrode finger 203 and electrode finger 204. Electrode finger 201 has a positive electrical polarity in the second resonator P1-2, while the symmetrical electrode finger 204 has a negative electrical polarity in the second resonator P1-2. The electric field in the third region between electrode finger 201 and electrode finger 202 is in a third direction. Electrode finger 202 has a negative electrical polarity in the second resonator P1-1, while the symmetrical electrode finger 203 has a positive electrical polarity in the second resonator P1-2. The electric field in the fourth region between electrode finger 203 and electrode finger 204 is in a fourth direction, which is opposite to the third direction.

[0062] In one embodiment, the series arm resonator group in the first resonant module 110 includes an even number of first resonators, and the parallel arm resonator group in the first resonant module 110 includes an even number of second resonators. The even number of first resonators are connected in series and have the same resonant frequency, and the even number of second resonators are connected in series and have the same resonant frequency. In each series path, the electric fields of two adjacent first resonators are in opposite directions, and the electric fields of two adjacent second resonators are in opposite directions.

[0063] For example, Figure 4 As shown, the series arm resonator group S1 includes a first resonator S1-1 and a first resonator S1-2, and the parallel arm resonator group P1 includes a second resonator P1-1 and a second resonator P1-2. By connecting S1 and P1 in the first resonant module 110 at the end of the signal flow path in series, S1 and P1 are split into S1-1, S1-2, P1-1, and P1-2. S1-1 and S1-2, P1-1, and P1-2 can be completely identical resonators, configured so that the resonant frequency is the same and the electric fields of adjacent resonators are in opposite directions. This can reduce the intensity of the nonlinear term of the first resonant module 110 itself by canceling the nonlinear terms of the resonators.

[0064] For example, Figure 4 As shown, the series arm resonator group S1 in the first resonant module 110 includes a first A resonator S1-1 and a first B resonator S1-2, and the parallel arm resonator group in the first resonant module 110 includes a second A resonator P1-1 and a second B resonator P1-2; the first end of the first A resonator S1-1 is connected to the output end Output of the filter 100, the second end of the first A resonator S1-1 is connected to the first end of the first B resonator S1-2, and the second end of the first B resonator S1-2 is connected to the resonance module of the previous level (other resonators 120); the first end of the second A resonator P1-1 is connected to the second end of the first B resonator S1-2, the second end of the second A resonator P1-1 is connected to the first end of the second B resonator P1-2, and the second end of the second B resonator P1-2 is connected to the ground end.

[0065] In one embodiment, two adjacent first resonators in the first resonant module 110 share a common first bus bar. With the first bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent first resonators are symmetrically arranged, and the symmetrical electrode fingers have opposite electrical polarities in their respective first resonators.

[0066] It should be noted that the first resonator in the first resonance module 110 may include at least one interdigital transducer, which includes two parallel and spaced bus bars and a plurality of electrode fingers located between the two bus bars. The two adjacent first resonators in the first resonance module 110 may be integrally arranged, so that the first bus bar may be shared. The plurality of electrode fingers in the two adjacent first resonators may be symmetrically distributed with the first bus bar as the axis of symmetry. The mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators, so the nonlinear distortions generated can cancel each other out, thereby reducing the intensity of the nonlinear distortion of the first resonance module 110 itself.

[0067] For example, Figure 4 and Figure 5 As shown, the first resonator S1-1 and the first resonator S1-2 are connected in series, and the first resonator S1-1 and the first resonator S1-2 share a first bus bar 11. The multiple electrode fingers in the first resonator S1-2 and the first resonator S1-1 are arranged symmetrically with the first bus bar 11 as the axis of symmetry. Electrode finger 101 has a positive electrical polarity in the first resonator S1-2, while the symmetrical electrode finger 104 has a negative electrical polarity in the first resonator S1-1. Electrode finger 102 has a negative electrical polarity in the first resonator S1-2, while the symmetrical electrode finger 103 has a positive electrical polarity in the first resonator S1-1.

[0068] In one embodiment, two adjacent second resonators in the first resonant module 110 share a second bus bar. With the second bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent second resonators are symmetrically arranged, and the symmetrical electrode fingers have opposite electrical polarities in their respective second resonators.

[0069] It should be noted that the second resonator can also include at least one interdigital transducer, which includes two parallel and spaced bus bars and a plurality of electrode fingers located between the two bus bars. Two adjacent second resonators can share the second bus bar. The plurality of electrode fingers in the two adjacent second resonators can be symmetrically distributed with the second bus bar as the symmetry axis. Similarly, the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators, so the nonlinear distortions generated can cancel each other out, thereby reducing the nonlinear distortion of the first resonant module 110 itself.

[0070] For example, Figure 4 and Figure 6 As shown, the second resonator P1-1 and the second resonator P1-2 are connected in series. The second resonator P1-1 and the second resonator P1-2 share a second bus bar 21. The multiple electrode fingers in the second resonator P1-1 and the second resonator P1-2 are symmetrically arranged with the second bus bar 21 as the axis of symmetry. Electrode finger 201 has a positive electrical polarity in the second resonator P1-1, while the electrode finger 204, which is symmetrical to it, has a negative electrical polarity in the second resonator P1-2. Electrode finger 202 has a negative electrical polarity in the second resonator P1-1, while the electrode finger 203, which is symmetrical to it, has a positive electrical polarity in the second resonator P1-2.

[0071] In one embodiment, two adjacent first resonators in the first resonant module 110 share a first bus bar, and two adjacent second resonators in the first resonant module 110 share a second bus bar. With the first bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent first resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators. With the second bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent second resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators.

[0072] For example, Figure 7 As shown, the series arm resonator group in the first resonant module 110 includes an even number of first resonators connected in series and having the same resonant frequency, and the parallel arm resonator group in the first resonant module 110 includes an even number of second resonators connected in series and having the same resonant frequency, wherein the electric field directions of two adjacent first resonators are opposite, and the electric field directions of two adjacent second resonators are opposite. After using this method, a 29dBm CW wave is loaded to the input of the filter 100, and the power of the quadratic nonlinear term H2 in the passband is measured to be below -56dBm, and the power of the cubic nonlinear term H3 in the passband is below -50dBm. Compared with the results before the improvement, Figure 3 The effect shown, Figure 7 The overall nonlinearity of the filter shown is improved by 6-10dB.

[0073] In one embodiment, the resonant modules 120 other than the first resonant module 110 in the plurality of resonant modules include at least one second resonant module. The series arm resonator group in the second resonant module includes an even number of third resonators, which are connected in series and have the same resonant frequency.

[0074] It should be noted that the second resonant module is at least one of the other resonant modules 120 other than the first resonant module 110, and the even-numbered third resonators can be identical resonators. When there is only one second resonant module, the even-numbered third resonators in the second resonant module have the same resonant frequency, and the electric field directions of two adjacent third resonators are opposite. When there are multiple second resonant modules, the even-numbered third resonators in the multiple second resonant modules are connected in series and have the same resonant frequency, and the electric field directions of two adjacent third resonators on each series path are opposite. Alternatively, the electric field directions of two adjacent third resonators on each series path are the same, but the electric field directions on adjacent series paths are opposite.

[0075] That is, by canceling the nonlinear terms of the series arm resonator groups in one or more second resonant modules, the nonlinear distortion generated by the second resonant module itself or as a whole can be weakened, thereby further reducing the intensity of the nonlinear distortion generated by the filter 100 as a whole.

[0076] For example, Figure 8 As shown, the other resonant module 120 includes a second resonant module 121, and the series arm resonator group S3 in the second resonant module 121 includes a third resonator S3-1 and a third resonator S3-2. The third resonator S3-1 and the third resonator S3-2 are connected in series and have the same resonant frequency. In some embodiments, the electric field directions of the third resonator S3-1 and the third resonator S3-2 may be opposite. In some embodiments, the electric field directions of the third resonator S3-1 and the third resonator S3-2 may be the same, but they are opposite to the electric field directions of other third resonators on the adjacent series path (such as the third resonator in S2 or S4).

[0077] In one embodiment, the other resonant modules 120 except the first resonant module 110 in the plurality of resonant modules include at least one second resonant module. The parallel arm resonator group in the second resonant module includes an even number of fourth resonators, and the even number of fourth resonators have the same resonant frequency.

[0078] It should be noted that an even number of fourth resonators can be identical resonators. The even number of fourth resonators in the second resonant module have the same resonant frequency, and the even number of fourth resonators can be connected in series or in parallel. In the series path or the parallel path, the electric field directions of two adjacent third resonators can be opposite or the same, which can offset the nonlinear terms generated by the one or more second resonant modules, thereby reducing the intensity of the nonlinear distortion generated by the filter 100 as a whole.

[0079] For example, Figure 9 As shown, the other resonant module 120 includes a second resonant module 121, and the parallel arm resonator group P3 in the second resonant module 121 includes a fourth resonator P3-1 and a fourth resonator P3-2. The fourth resonator P3-1 and the fourth resonator P3-2 are connected in series and have the same resonant frequency. In some embodiments, the electric field directions of the fourth resonator P3-1 and the fourth resonator P3-2 may be opposite. In some embodiments, the electric field directions of the fourth resonator P3-1 and the fourth resonator P3-2 may be the same, but they are opposite to the electric field directions of other fourth resonators on the adjacent series path (such as the fourth resonator in P2 or P4).

[0080] In one embodiment, the resonant modules 120 other than the first resonant module 110 in the plurality of resonant modules include at least one second resonant module. The series arm resonator group in the second resonant module includes an even number of third resonators, which are connected in series and have the same resonant frequency. The parallel arm resonator group in the second resonant module includes an even number of fourth resonators, which have the same resonant frequency.

[0081] It should be noted that the even number of third resonators and the even number of fourth resonators can be identical resonators. The even number of third resonators and the even number of fourth resonators have the same resonant frequency, thereby offsetting the nonlinear terms generated by the one or more second resonant modules, thereby further suppressing the nonlinear distortion generated by the filter 100 as a whole.

[0082] For example, Figure 10 As shown, the other resonant module 120 includes a second resonant module 121, and the series arm resonator group S3 in the second resonant module includes a third resonator S3-1 and a third resonator S3-2. The parallel arm resonator group P3 in the second resonant module 121 includes a fourth resonator P3-1 and a fourth resonator P3-2. The third resonator S3-1 and the third resonator S3-2 are connected in series and have the same resonant frequency, and the fourth resonator P3-1 and the fourth resonator P3-2 are connected in series and have the same resonant frequency. The electric field directions of the third resonator S3-1 and the third resonator S3-2 can be opposite, and the electric field directions of the fourth resonator P3-1 and the fourth resonator P3-2 can be opposite, for example, the electric field direction of the third resonator S3-1 is e S3-1 and the electric field direction e of the third resonator S3-2 S3-2 In the opposite direction, the electric field direction of the fourth resonator P3-1 is e p3-1 and the electric field direction e of the fourth resonator P3-2 p3-2 Facing each other.

[0083] For example, Figure 11 As shown, the filter 100 includes a plurality of second resonant modules 121, wherein the series arm resonator group S2 includes a third resonator S2-1 and a third resonator S2-2, the series arm resonator group S3 includes a third resonator S3-1 and a third resonator S3-2, and the series arm resonator group S4 includes a third resonator S4-1 and a third resonator S4-2. The parallel arm resonator group P2 includes a fourth resonator P2-1 and a fourth resonator P2-2, the parallel arm resonator group P3 includes a fourth resonator P3-1 and a fourth resonator P3-2, and the parallel arm resonator group P4 includes a fourth resonator P4-1 and a fourth resonator P4-2. The electric field direction e of the third resonator S3-1 is S2-1 and the electric field direction e of the third resonator S3-2 S2-2 In the opposite direction, the electric field direction of the fourth resonator P3-1 is e p2-1 and the electric field direction e of the fourth resonator P3-2 p2-2 The electric field direction of the third resonator S3-1 is e S3-1 and the electric field direction e of the third resonator S3-2 S3-2 In the opposite direction, the electric field direction of the fourth resonator P3-1 is e p3-1 and the electric field direction e of the fourth resonator P3-2 p3-2The electric field direction of the third resonator S4-1 is e S4-1 and the electric field direction e of the third resonator S4-2 S4-2 In the opposite direction, the electric field direction of the fourth resonator P4-1 is e p4-1 and the electric field direction e of the fourth resonator P4-2 p4-2 Facing each other.

[0084] In one embodiment, two adjacent third resonators in the second resonant module share a third bus bar, and the electrode fingers in the two adjacent third resonators are symmetrically arranged with the third bus bar as a symmetry axis.

[0085] It should be noted that the two adjacent third resonators in the second resonant module can be integrally arranged and thus share a third bus bar. The multiple electrode fingers in the two adjacent third resonators can be symmetrically distributed with the third bus bar as the axis of symmetry. The mutually symmetrical electrode fingers have opposite electrical polarities in their respective third resonators, or the mutually symmetrical electrode fingers have the same electrical polarity in their respective third resonators but the electric fields formed by the two adjacent series paths are in opposite directions. Therefore, the nonlinear distortions generated can cancel each other out, thereby reducing the intensity of the nonlinear distortion of the second resonant module itself.

[0086] In one embodiment, an even number of fourth resonators in the second resonant module are connected in series, two adjacent fourth resonators share a fourth bus bar, and the electrode fingers in two adjacent fourth resonators are symmetrically arranged with the fourth bus bar as the symmetry axis.

[0087] It should be noted that when an even number of fourth resonators in the second resonant module are connected in series, since two adjacent fourth resonators can be integrally arranged, the two adjacent fourth resonators can share a fourth bus bar. The multiple electrode fingers in the two adjacent fourth resonators can be symmetrically distributed with the fourth bus bar as the axis of symmetry. Similarly, the mutually symmetrical electrode fingers have opposite electrical polarities in their respective fourth resonators, or the mutually symmetrical electrode fingers have the same electrical polarity in their respective third resonators but the electric fields formed by the two adjacent series paths are in opposite directions. Therefore, the resulting nonlinear distortion can cancel each other out, thereby reducing the intensity of the nonlinear distortion of the second resonant module itself.

[0088] In one embodiment, an even number of third resonators in the second resonant module are connected in series, with two adjacent third resonators sharing a third bus bar. An even number of fourth resonators in the second resonant module are connected in series, with two adjacent fourth resonators sharing a fourth bus bar. The electrode fingers in two adjacent third resonators are symmetrically arranged with the third bus bar as the axis of symmetry. The electrode fingers in two adjacent fourth resonators are symmetrically arranged with the fourth bus bar as the axis of symmetry.

[0089] It can be understood that the specific electrode finger settings of the third resonator and the fourth resonator in the second resonant module can refer to Figure 5 、 Figure 6 The relevant examples shown are not specifically limited in the embodiments of the present application.

[0090] In one embodiment, the series arm resonator groups of all resonant modules in the filter 100 are split into an even number of series resonators, and the parallel arm resonator groups of all resonant modules in the filter 100 are split into an even number of parallel resonators. An even number of series resonators are connected in series and have the same resonant frequency. In the series path, the electric field directions of two adjacent series resonators are opposite. An even number of parallel resonators are connected in series and have the same resonant frequency. In the series path, the electric field directions of two adjacent parallel resonators are opposite. In this way, not only can the nonlinear terms of each resonator be offset to a certain extent, but the resonator area can also be increased, and the power density borne by the series arm resonator group and the parallel arm resonator group can be reduced, thereby improving the power tolerance of the filter 100.

[0091] In other words, by splitting all series-arm resonator groups and parallel-arm resonator groups in the aforementioned filter 100 into an even number of identical resonators, the nonlinear distortion between the resonators can be offset, further suppressing nonlinear distortion. In addition to improving the nonlinear effect, the area of the resonators after cascading is increased, the resonator power density is reduced, and the power capacity is also significantly improved.

[0092] For example, Figure 12 As shown, the filter 100 includes a first resonance module 110 and a plurality of second resonance modules 121. The series arm resonator group S1 in the first resonance module 110 includes a first resonator S1-1 and a first resonator S1-2. The electric field direction e of the first resonator S1-1 is S1-1 is the first direction, and the electric field direction e of the first resonator S1-2 is S1-2 The parallel arm resonator group P1 includes a second resonator P1-1 and a second resonator P1-2. The electric field direction e of the second resonator P1-1 is P1-1 The electric field direction of the second resonator P1-2 is e P1-2 The third direction is opposite to the fourth direction.

[0093] like Figure 12 As shown, in the plurality of second resonant modules 121, the electric field direction e of the third resonator S3-1 is S2-1 is the first direction, and the electric field direction e of the third resonator S3-2 is S2-2 The electric field direction e of the fourth resonator P3-1 is p2-1 The electric field direction of the fourth resonator P3-2 is ep2-2 The electric field direction of the third resonator S3-1 is e S3-1 is the first direction, and the electric field direction e of the third resonator S3-2 is S3-2 The electric field direction e of the fourth resonator P3-1 is p3-1 The electric field direction of the fourth resonator P3-2 is e p3-2 The electric field direction of the third resonator S4-1 is e S4-1 is the first direction, and the electric field direction e of the third resonator S4-2 is S4-2 is the second direction, and the electric field direction e of the fourth resonator P4-1 is p4-1 The electric field direction of the fourth resonator P4-2 is e p4-2 The fourth direction.

[0094] For example, Figure 13 As shown, the series arm resonator groups of all resonant modules in the filter 100 are split into an even number of series resonators connected in series and with the same resonant frequency, and the parallel arm resonator groups of all resonant modules in the filter 100 are split into an even number of parallel resonators connected in series and with the same resonant frequency. After using this method, a 29dBm CW wave is applied to the input of the filter 100, and the power of the quadratic nonlinear term H2 in the passband is measured to be below -60dBm, and the power of the cubic nonlinear term H3 in the passband is below -56dBm. Compared with the original Figure 7 The effect shown, Figure 13 The overall nonlinear distortion improvement shown is 4-6dB.

[0095] In one embodiment, each series-arm resonator group and parallel-arm resonator group includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate. The interdigital transducer includes two comb-shaped electrodes arranged opposite each other in a first direction, and the electrode fingers of the two comb-shaped electrodes are arranged alternately and spaced apart. The structural parameters of each resonator in the parallel-arm resonator group are greater than the structural parameters of each resonator in the series-arm resonator group. The structural parameters include at least one of the aperture, the duty cycle, and the length of the low acoustic impedance region in the aperture region in the first direction. The parallel-arm resonator group can be a parallel-arm resonator group in the first resonant module, a parallel-arm resonator group in another resonant module, or a parallel-arm resonator group in the aforementioned second resonant module.

[0096] It can be understood that the first direction is the arrangement direction of the two comb electrodes, and the comb electrodes include a bus bar and a plurality of electrode fingers, one end of the plurality of electrode fingers is connected to the bus bar, and the other end is a free end. The two comb electrodes are arranged relative to each other so that the electrode fingers of one comb electrode and the electrode fingers of the other comb electrode are arranged alternately and at intervals. The aperture refers to the length of the area in the first direction where the electrode fingers overlap in their arrangement direction; the duty cycle refers to the ratio of the width of the electrode finger in the interdigital transducer to the center line of the two adjacent electrode fingers; the area where the aperture is located is generally the resonant area, which includes the middle area and the low acoustic impedance area on both sides of the middle area in the first direction. The acoustic impedance of the surface acoustic wave in the low acoustic impedance area is smaller than the acoustic impedance in the middle area, and the low acoustic impedance can be achieved by increasing the mass load in the low acoustic impedance area.

[0097] It should be noted that, as mentioned above, the nonlinear test Figure 3 、 Figure 7 and Figure 13 As shown, the curves for the quadratic nonlinear term H2 and the cubic nonlinear term H3 exhibit significant fluctuations. This phenomenon occurs because spurious modes such as the SH mode and transverse mode within the passband of filter 100 cause a passband dip, which is reflected in the significant fluctuations in H2 and H3. By adjusting structural parameters such as the duty cycle, aperture, and length of the low acoustic impedance region of each resonator in the series and parallel arms, spurious modes within the passband can be suppressed to a certain extent, effectively reducing the intensity of H2 and H3, resulting in improved passband and nonlinear flatness.

[0098] The filter 100 provided in the above embodiment includes multiple resonant modules, each of which includes at least one series-arm resonator group and at least one parallel-arm resonator group. The multiple resonant modules include a first resonant module 110, which is connected to the output terminal "Output" of the filter 100 and is located at the end of the signal flow path of the filter 100. The resonant frequency of at least one parallel-arm resonator group in the first resonant module 110 is configured between a first frequency and a second frequency. The first frequency is less than twice the center frequency of the filter 100, and the second frequency is greater than three times the center frequency of the filter 100. Setting the resonant frequency of the parallel-arm resonator group in the first resonant module 110 at the end of the signal flow path to between two and three times the center frequency can effectively suppress the frequency components generated by the resonant modules at the front of the first resonant module 110, thereby suppressing the nonlinear distortion generated by the resonant modules at the front of the signal flow path, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter 100.

[0099] Please refer to Figure 14 , Figure 14This is a circuit diagram of another implementation of the filter provided in an embodiment of the present application.

[0100] like Figure 14 As shown, filter 200 includes multiple resonant modules, each of which includes at least one series-arm resonator group and at least one parallel-arm resonator group. Each series-arm resonator group is connected in series between the input and output of filter 200, and each parallel-arm resonator group is connected between one end of the series-arm resonator group in the same resonant module and ground.

[0101] It should be noted that Figure 14 For illustration, it is taken that the plurality of resonance modules in the filter 100 include a first resonance module 110 and a plurality of other resonance modules 120 . In actual applications, the filter 100 may include a smaller or larger number of resonance modules. Figure 14 In the example of each resonant module including one series arm resonator group and one parallel arm resonator group, the number of series arm resonator groups and parallel arm resonator groups in the resonant module in actual applications can be two or more. Moreover, the number of series arm resonator groups and parallel arm resonator groups in each resonant module can be the same or different. For example, a resonant module can include one series arm resonator group and two parallel arm resonator groups.

[0102] Each parallel-arm resonator group may include at least one resonator, and each resonator in each parallel-arm resonator group is connected between one end of a series-arm resonator group in the same resonant module and a ground terminal. Each series-arm resonator group and each parallel-arm resonator group may be integrally arranged. For example, in each series-arm resonator group and each parallel-arm resonator group, the interdigital transducers of two or more resonators may be arranged on the same piezoelectric substrate.

[0103] In one embodiment, the series arm resonator group in the first resonant module 210 includes an even number of first resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent first resonators have opposite directions.

[0104] for example, Figure 14 The series arm resonator group S1 shown includes a first resonator S1-1 and a first resonator S1-2. The first resonator S1-1 and the first resonator S1-2 are connected in series and have the same resonant frequency. The electric field directions of the adjacent first resonators S1-1 and S1-2 are opposite, wherein the electric field direction of the first resonator S1-1 is e S1-1 is the first direction, and the electric field direction e of the first resonator S1-2 is S1-2 The first direction is the second direction, and the first direction and the second direction are arranged opposite to each other.

[0105] It should be noted that since the first resonance module 210 itself will also generate nonlinear distortion, the series arm resonator group (such as S1) in the first resonance module 210 can be configured as an even number of first resonators (such as S1-1 and S1-2). The resonant frequencies of the even number of first resonators are the same, and the electric field directions of the two adjacent first resonators (such as S1-1 and S1-2) are opposite. Therefore, the nonlinear distortion of the first resonance module 210 itself can be weakened by canceling the nonlinear terms of the resonators, thereby weakening the intensity of the nonlinear distortion generated by the filter 200 as a whole.

[0106] In one embodiment, the parallel arm resonator group in the first resonant module 210 includes an even number of second resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent second resonators have opposite directions.

[0107] for example, Figure 14 The parallel arm resonator group P1 shown includes a second resonator P1-1 and a second resonator P1-2. The second resonator P1-1 and the second resonator P1-2 are connected in series and have the same resonant frequency. The electric field directions of the adjacent second resonators P1-1 and P1-2 are opposite, wherein the electric field direction of the second resonator P1-1 is e P1-1 The electric field direction of the second resonator P1-2 is e P1-2 The third direction is opposite to the fourth direction.

[0108] It should be noted that by configuring the parallel arm resonator group in the first resonant module 210 as an even number of second resonators, the resonant frequencies of the even number of second resonators are the same and the electric field directions of two adjacent second resonators are opposite. Therefore, the nonlinear distortion of the first resonant module 210 itself can be weakened by canceling the nonlinear terms of the resonators, thereby suppressing the nonlinear distortion generated by the filter 200 as a whole.

[0109] In one embodiment, the series-arm resonator group in the first resonant module 210 includes an even number of first resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent first resonators are directed in opposite directions. The parallel-arm resonator group in the first resonant module 210 includes an even number of second resonators, which are connected in series and have the same resonant frequency. In the series path, the electric fields of two adjacent second resonators are directed in opposite directions.

[0110] For example, Figure 14As shown, the series arm resonator group S1 includes a first resonator S1-1 and a first resonator S1-2, and the parallel arm resonator group P1 includes a second resonator P1-1 and a second resonator P1-2. By connecting S1 and P1 in the first resonant module 110 at the end of the signal flow path in series, S1 and P1 are split into S1-1, S1-2, P1-1, and P1-2. S1-1 and S1-2, P1-1, and P1-2 can be completely identical resonators, configured so that the resonant frequency is the same and the electric field directions of adjacent resonators are opposite. This can reduce the nonlinear distortion intensity of the first resonant module 210 itself by canceling the nonlinear terms of the resonators.

[0111] In one embodiment, two adjacent first resonators in the first resonant module 210 share a first bus bar; with the first bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent first resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators.

[0112] It should be noted that the first resonator in the first resonance module 210 may include at least one interdigital transducer, which includes two parallel and spaced bus bars and a plurality of electrode fingers located between the two bus bars. The two adjacent first resonators in the first resonance module 210 may be integrally arranged, and thus may share the first bus bar. The plurality of electrode fingers in the two adjacent first resonators may be symmetrically distributed with the first bus bar as the axis of symmetry. The mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators, and thus the nonlinear distortions generated may cancel each other out, thereby reducing the intensity of the nonlinear distortion of the first resonance module 210 itself.

[0113] In one embodiment, two adjacent second resonators in the first resonant module 210 share a second bus bar; with the second bus bar as the axis of symmetry, the multiple electrode fingers in the two adjacent second resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators.

[0114] It should be noted that the second resonator can also include at least one interdigital transducer, which includes two parallel and spaced bus bars and a plurality of electrode fingers located between the two bus bars. Two adjacent second resonators can share the second bus bar. The plurality of electrode fingers in the two adjacent second resonators can be symmetrically distributed with the second bus bar as the symmetry axis. Similarly, the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators, so the nonlinear distortions generated can cancel each other out, thereby reducing the nonlinear distortion intensity of the first resonant module 210 itself.

[0115] In one embodiment, the resonant frequency of at least one parallel arm resonator group in the first resonant module 210 is configured within a first frequency band or a second frequency band, the first frequency band being centered at twice the center frequency of the filter 100 , and the second frequency band being centered at three times the center frequency of the filter 100 .

[0116] It should be noted that the resonant frequency of the parallel arm resonator group P1 in the first resonant module 110 is configured within a first frequency band centered on 2f0, or the resonant frequency of the parallel arm resonator group P1 in the first resonant module 110 is configured within a second frequency band centered on 3f0, so that the nonlinear distortion generated by other resonant modules 120 before the first resonant module 110 can be suppressed, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter 100.

[0117] For example, the first frequency band includes 1.8 times f0 to 2.2 times f0, and the second frequency band includes 2.8 times f0 to 3.2 times f0, where f0 represents the center frequency of the filter 100. When the resonant frequency of the parallel arm resonator group P1 in the first resonant module 210 is arranged near 2 times f0 and 3 times f0, the filter 200 has a higher suppression degree at the 2f0 and 3f0 frequency points, and the resulting nonlinear distortion is relatively weak.

[0118] In one embodiment, the resonant modules 220 other than the first resonant module 210 in the plurality of resonant modules include at least one second resonant module 221. The series arm resonator group in the second resonant module 221 includes an even number of third resonators, which are connected in series and have the same resonant frequency.

[0119] It should be noted that the second resonant module is at least one of the other resonant modules 220 other than the first resonant module 210, and the even-numbered third resonators can be identical resonators. When there is only one second resonant module, the even-numbered third resonators in the second resonant module have the same resonant frequency, and the electric field directions of two adjacent third resonators are opposite. When there are multiple second resonant modules, the even-numbered third resonators in the multiple second resonant modules are connected in series and have the same resonant frequency, and the electric field directions of two adjacent third resonators on each series path are opposite. Alternatively, the electric field directions of two adjacent third resonators on each series path are the same, but the electric field directions on adjacent series paths are opposite.

[0120] For example, Figure 15As shown, the other resonant module 220 includes a second resonant module 221, and the series arm resonator group S3 in the second resonant module 221 includes a third resonator S3-1 and a third resonator S3-2. The third resonator S3-1 and the third resonator S3-2 are connected in series and have the same resonant frequency. In some embodiments, the electric field directions of the third resonator S3-1 and the third resonator S3-2 may be opposite. In some embodiments, the electric field directions of the third resonator S3-1 and the third resonator S3-2 may be the same, but they are opposite to the electric field directions of other third resonators on the adjacent series path (such as the third resonator in S2 or S4).

[0121] In one embodiment, the resonant modules 220 other than the first resonant module 210 in the plurality of resonant modules include at least one second resonant module 221. The parallel arm resonator group in the second resonant module 221 includes an even number of fourth resonators, and the even number of fourth resonators have the same resonant frequency.

[0122] It should be noted that an even number of fourth resonators can be identical resonators. The even number of fourth resonators in the second resonant module have the same resonant frequency, and an even number of fourth resonators can be connected in series or in parallel. In the series path or the parallel path, the electric field directions of two adjacent third resonators can be opposite or the same, as long as the nonlinear terms generated by the one or more second resonant modules can be offset, thereby reducing the intensity of the nonlinear distortion generated by the filter 100 as a whole.

[0123] For example, Figure 15 As shown, the other resonant module 120 includes a second resonant module 221, and the parallel arm resonator group P3 in the second resonant module 221 includes a fourth resonator P3-1 and a fourth resonator P3-2. The fourth resonator P3-1 and the fourth resonator P3-2 are connected in series and have the same resonant frequency. In some embodiments, the electric field directions of the fourth resonator P3-1 and the fourth resonator P3-2 may be opposite. In some embodiments, the electric field directions of the fourth resonator P3-1 and the fourth resonator P3-2 may be the same, but they are opposite to the electric field directions of other fourth resonators on the adjacent series path (such as the fourth resonator in P2 or P4).

[0124] In one embodiment, the resonant modules 220 other than the first resonant module 210 in the plurality of resonant modules include at least one second resonant module 221. The series arm resonator group in the second resonant module 221 includes an even number of third resonators, which are connected in series and have the same resonant frequency. The parallel arm resonator group in the second resonant module 221 includes an even number of fourth resonators, which have the same resonant frequency.

[0125] It should be noted that the even number of third resonators and the even number of fourth resonators can be identical resonators. The even number of third resonators and the even number of fourth resonators have the same resonant frequency, thereby offsetting the nonlinear terms generated by the one or more second resonant modules, thereby reducing the intensity of the nonlinear distortion generated by the filter 100 as a whole.

[0126] For example, Figure 15 As shown, the filter 100 includes a plurality of second resonant modules 121, wherein the series arm resonator group S2 includes a third resonator S2-1 and a third resonator S2-2, the series arm resonator group S3 includes a third resonator S3-1 and a third resonator S3-2, and the series arm resonator group S4 includes a third resonator S4-1 and a third resonator S4-2. The parallel arm resonator group P2 includes a fourth resonator P2-1 and a fourth resonator P2-2, the parallel arm resonator group P3 includes a fourth resonator P3-1 and a fourth resonator P3-2, and the parallel arm resonator group P4 includes a fourth resonator P4-1 and a fourth resonator P4-2. The electric field direction e of the third resonator S3-1 is S2-1 and the electric field direction e of the third resonator S3-2 S2-2 In the opposite direction, the electric field direction of the fourth resonator P3-1 is e p2-1 and the electric field direction e of the fourth resonator P3-2 p2-2 The electric field direction of the third resonator S3-1 is e S3-1 and the electric field direction e of the third resonator S3-2 S3-2 In the opposite direction, the electric field direction of the fourth resonator P3-1 is e p3-1 and the electric field direction e of the fourth resonator P3-2 p3-2 The electric field direction of the third resonator S4-1 is e S4-1 and the electric field direction e of the third resonator S4-2 S4-2 In the opposite direction, the electric field direction of the fourth resonator P4-1 is e p4-1 and the electric field direction e of the fourth resonator P4-2 p4-2 Facing each other.

[0127] In one embodiment, two adjacent third resonators in the second resonant module share a third bus bar, and the electrode fingers in the two adjacent third resonators are symmetrically arranged with the third bus bar as a symmetry axis.

[0128] It should be noted that the two adjacent third resonators in the second resonant module can be integrally arranged and thus share a third bus bar. The multiple electrode fingers in the two adjacent third resonators can be symmetrically distributed with the third bus bar as the axis of symmetry. The mutually symmetrical electrode fingers have opposite electrical polarities in their respective third resonators, or the mutually symmetrical electrode fingers have the same electrical polarity in their respective third resonators but the electric fields formed by the two adjacent series paths are in opposite directions. Therefore, the nonlinear distortions generated can cancel each other out, thereby reducing the intensity of the nonlinear distortion of the second resonant module itself.

[0129] In one embodiment, an even number of fourth resonators in the second resonant module are connected in series, two adjacent fourth resonators share a fourth bus bar, and the electrode fingers in two adjacent fourth resonators are symmetrically arranged with the fourth bus bar as the symmetry axis.

[0130] It should be noted that when an even number of fourth resonators in the second resonant module are connected in series, since two adjacent fourth resonators can be integrally arranged, the two adjacent fourth resonators can share a fourth bus bar. The multiple electrode fingers in the two adjacent fourth resonators can be symmetrically distributed with the fourth bus bar as the axis of symmetry. Similarly, the mutually symmetrical electrode fingers have opposite electrical polarities in their respective fourth resonators, or the mutually symmetrical electrode fingers have the same electrical polarity in their respective third resonators but the electric fields formed by the two adjacent series paths are in opposite directions. Therefore, the resulting nonlinear distortion can cancel each other out, thereby reducing the intensity of the nonlinear distortion of the second resonant module itself.

[0131] In one embodiment, an even number of third resonators in the second resonant module are connected in series, with two adjacent third resonators sharing a third bus bar. An even number of fourth resonators in the second resonant module are connected in series, with two adjacent fourth resonators sharing a fourth bus bar. The electrode fingers in two adjacent third resonators are symmetrically arranged with the third bus bar as the axis of symmetry. The electrode fingers in two adjacent fourth resonators are symmetrically arranged with the fourth bus bar as the axis of symmetry.

[0132] In one embodiment, if Figure 15As shown, the series arm resonator groups of all the resonant modules (including the first resonant module 210 and the plurality of second resonant modules 221) in the filter 200 are split into an even number of series resonators, and the parallel arm resonator groups of all the resonant modules in the filter 200 are split into an even number of parallel resonators. An even number of series resonators are connected in series and have the same resonant frequency. In the series path, the electric field directions of two adjacent series resonators are opposite. An even number of parallel resonators are connected in series and have the same resonant frequency. In the series path, the electric field directions of two adjacent parallel resonators are opposite. In this way, not only can the nonlinear terms of each resonator be offset to a certain extent, but the resonator area can also be increased, and the power density borne by the series arm resonator group and the parallel arm resonator group can be reduced, thereby improving the power tolerance of the filter 200.

[0133] In other words, by splitting all series-arm and parallel-arm resonator groups in filter 200 into an even number of identical resonators, the nonlinear distortion between the resonators can be offset, further suppressing nonlinear distortion. In addition to improving the nonlinear effect, the area of the cascaded resonators is increased, the resonator power density is reduced, and the power handling capacity is significantly improved.

[0134] The filter 200 described in the above embodiment includes multiple resonant modules, each of which includes at least one series-arm resonator group and at least one parallel-arm resonator group. The multiple resonant modules include a first resonant module 210, which is connected to the output terminal "Output" of the filter 200 and is located at the end of the signal flow path of the filter 200. The series-arm resonator group in the first resonant module 210 includes an even number of first resonators, which are connected in series and have the same resonant frequency; in the series path, the electric fields of two adjacent first resonators are in opposite directions; and / or the parallel-arm resonator group in the first resonant module 210 includes an even number of second resonators, which are connected in series and have the same resonant frequency; in the series path, the electric fields of two adjacent second resonators are in opposite directions. In this way, the frequency components generated by the first resonant module 210 itself can be effectively suppressed, thereby suppressing the nonlinear distortion generated at the end of the signal flow path, thereby effectively reducing the intensity of the nonlinear distortion generated by the filter 200.

[0135] Please refer to Figure 16 , Figure 16 A schematic diagram of the RF front-end module provided in an embodiment of the present application.

[0136] like Figure 16 As shown, the RF front-end module 300 includes the filter 320 described in the above embodiment. The filter 320 is used to filter out signals with a specific frequency or signals other than the specific frequency in the signal.

[0137] Filter 320 may be filter 100 or filter 200 described in the above embodiment. Filter 320 may be applicable to either a transmitting circuit or a receiving circuit. When the filter is configured in a transmitting circuit, the filter's input serves as the internal interface of the transmitting circuit, and the filter's output is connected to the transmitting circuit's antenna interface. When the filter is configured in a receiving circuit, the filter's input is connected to the transmitting circuit's antenna interface, and the filter's output serves as the internal interface of the transmitting circuit.

[0138] In one embodiment, the RF front-end module 300 may further include a substrate, and the multiple resonant modules in the filter 320 may be disposed on the substrate.

[0139] This embodiment provides a radio frequency front-end module (RFFMM). This module integrates two or more discrete components, such as a radio frequency switch, a low-noise amplifier, a filter, a duplexer, a power amplifier, and a transformer, into a single module. This improves the module's integration and hardware performance while miniaturizing its size. Specifically, the RFFMM can be used in 4G and 5G communication devices, such as smartphones, tablets, and smartwatches.

[0140] With the development of information technology, 5G technology and 5G devices have higher requirements for the performance of RF front-end modules. The technical solution provided in this application can provide a filter and RF front-end module that can effectively suppress the nonlinear distortion generated by the filter, thereby better meeting the requirements of 5G technology and can be applied to 5G devices.

[0141] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections. They may refer to mechanical connections or electrical connections. They may refer to direct connections or indirect connections through an intermediary. They may refer to internal communication between two components or the interaction between two components.

[0142] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A filter, characterized in that: The filter includes a plurality of resonance modules, each of which includes at least one series arm resonator group and at least one parallel arm resonator group; each of the series arm resonator groups is connected in series between an input end and an output end of the filter, and each of the parallel arm resonator groups is connected between one end of the series arm resonator group in the same resonance module and a ground end; The multiple resonance modules include a first resonance module, which is connected to the output end of the filter and is located at the end of the signal flow path of the filter; the resonant frequency of at least one of the parallel arm resonator groups in the first resonance module is configured between a first frequency and a second frequency; wherein the first frequency is less than 2 times the center frequency of the filter, and the second frequency is greater than 3 times the center frequency of the filter.

2. The filter according to claim 1, wherein The resonant frequency of at least one of the parallel arm resonator groups in the first resonant module is configured in a first frequency band or a second frequency band, the first frequency band is centered on twice the center frequency of the filter, and the second frequency band is centered on three times the center frequency of the filter.

3. The filter according to claim 2, characterized in that The first frequency band includes 1.8 times f0 to 2.2 times f0, and the second frequency band includes 2.8 times f0 to 3.2 times f0, where f0 represents the center frequency of the filter.

4. The filter according to claim 1, wherein The first frequency is 1.8 times f0, and the second frequency is 3.2 times f0, where f0 represents the center frequency of the filter.

5. The filter according to claim 1, wherein The series arm resonator group in the first resonant module includes an even number of first resonators, the even number of first resonators are connected in series and have the same resonant frequency; in the series path, the electric fields of two adjacent first resonators are in opposite directions; and / or, The parallel arm resonator group in the first resonance module includes an even number of second resonators, which are connected in series and have the same resonance frequency; in the series path, the electric fields of two adjacent second resonators are in opposite directions.

6. The filter according to claim 5, characterized in that Two adjacent first resonators in the first resonant module share a first bus bar; with the first bus bar as a symmetry axis, a plurality of electrode fingers in two adjacent first resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators; and / or, Two adjacent second resonators in the first resonant module share a second bus bar; with the second bus bar as the symmetry axis, multiple electrode fingers in the two adjacent second resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators.

7. The filter according to claim 5, characterized in that The series arm resonator group in the first resonance module includes a first resonator A and a first resonator B, and the parallel arm resonator group in the first resonance module includes a second resonator A and a second resonator B; The first end of the first resonator A is connected to the output end of the filter, the second end of the first resonator A is connected to the first end of the first resonator B, and the second end of the first resonator B is connected to the resonance module of the previous stage; The first end of the second resonator A is connected to the second end of the first resonator B, the second end of the second resonator A is connected to the first end of the second resonator B, and the second end of the second resonator B is connected to the ground end.

8. The filter according to claim 1, wherein Each of the series-arm resonator group and the parallel-arm resonator group includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate, wherein the interdigital transducer includes two comb-shaped electrodes arranged opposite to each other in a first direction, and electrode fingers of the two comb-shaped electrodes are arranged alternately and at intervals; The structural parameters of each resonator in the parallel arm resonator group are greater than the structural parameters of each resonator in the series arm resonator group, and the structural parameters include at least one of the aperture, the duty cycle, and the length of the low acoustic impedance area in the area where the aperture is located in the first direction.

9. The filter according to any one of claims 1 to 8, characterized in that: The other resonance modules except the first resonance module among the plurality of resonance modules include at least one second resonance module; The series arm resonator group in the second resonance module includes an even number of third resonators, the even number of third resonators are connected in series and have the same resonance frequency; and / or, The parallel arm resonator group in the second resonance module includes an even number of fourth resonators, and the even number of fourth resonators have the same resonance frequency.

10. The filter according to claim 9, characterized in that Two adjacent third resonators in the second resonance module share a third bus bar; with the third bus bar as a symmetry axis, multiple electrode fingers in two adjacent third resonators are symmetrically arranged; and / or, An even number of the fourth resonators in the second resonance module are connected in series, and two adjacent fourth resonators share a fourth bus bar; with the fourth bus bar as the symmetry axis, the multiple electrode fingers in two adjacent fourth resonators are symmetrically arranged.

11. A filter, characterized in that: The filter includes a plurality of resonance modules, each of which includes at least one series arm resonator group and at least one parallel arm resonator group; each of the series arm resonator groups is connected in series between an input end and an output end of the filter, and each of the parallel arm resonator groups is connected between one end of the series arm resonator group in the same resonance module and a ground end; The plurality of resonance modules include a first resonance module, the first resonance module is connected to the output end of the filter, and the first resonance module is located at the end of the signal flow path of the filter; The series arm resonator group in the first resonant module includes an even number of first resonators, the even number of first resonators are connected in series and have the same resonant frequency; in the series path, the electric fields of two adjacent first resonators are in opposite directions; and / or, The parallel arm resonator group in the first resonance module includes an even number of second resonators, which are connected in series and have the same resonance frequency; in the series path, the electric fields of two adjacent second resonators are in opposite directions.

12. The filter according to claim 11, wherein Two adjacent first resonators in the first resonant module share a first bus bar; with the first bus bar as a symmetry axis, a plurality of electrode fingers in two adjacent first resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective first resonators; and / or, Two adjacent second resonators in the first resonant module share a second bus bar; with the second bus bar as the symmetry axis, multiple electrode fingers in the two adjacent second resonators are symmetrically arranged, and the mutually symmetrical electrode fingers have opposite electrical polarities in their respective second resonators.

13. The filter according to claim 11, wherein The resonant frequency of at least one of the parallel arm resonator groups in the first resonant module is configured in a first frequency band or a second frequency band, the first frequency band is centered on twice the center frequency of the filter, and the second frequency band is centered on three times the center frequency of the filter.

14. The filter according to claim 13, wherein The first frequency band includes 1.8 times f0 to 2.2 times f0, and the second frequency band includes 2.8 times f0 to 3.2 times f0, where f0 represents the center frequency of the filter.

15. The filter according to any one of claims 11 to 14, characterized in that: The other resonance modules except the first resonance module among the plurality of resonance modules include at least one second resonance module; The series arm resonator group in the second resonance module includes an even number of third resonators, the even number of third resonators are connected in series and have the same resonance frequency; and / or, The parallel arm resonator group in the second resonance module includes an even number of fourth resonators, and the even number of fourth resonators have the same resonance frequency.

16. A radio frequency front-end module, characterized in that: Comprising the filter according to any one of claims 1-15.

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