Filter and radio frequency module

Abstract

The application discloses a filter and a radio frequency module. The filter comprises a first DMS type filter and a second DMS type filter connected in parallel. The number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter is greater than the number of first electrode fingers of a first middle interdigital transducer, and the number of first electrode fingers in a first part of the first interdigital transducer is greater than the number of first electrode fingers in a second part. The number of second electrode fingers of at least one second end interdigital transducer of the second DMS type filter is less than the number of second electrode fingers of a second middle interdigital transducer, and the number of second electrode fingers in a fourth part of the second interdigital transducer is less than the number of second electrode fingers in a fifth part. The filter and the radio frequency module disclosed by the application have the advantages of widening a passband and optimizing deterioration of an in-band insertion loss at a passband edge.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a filter and a radio frequency module. Background Technology

[0002] Surface acoustic wave (SAW) filters are commonly used in modern communication systems due to their advantages such as small size, high stability, strong anti-interference capability, and high selectivity. SAW filter design primarily utilizes trapezoidal structures and DMS (Double-mode SAW) filters. DMS filters exhibit superior low-end suppression and size characteristics, making them widely used in filter and duplexer design. However, current technologies often suffer from narrow passbands and significant insertion losses at the passband edges, failing to adequately meet application requirements. Summary of the Invention

[0003] In view of this, the present invention proposes a filter and an RF module.

[0004] The filter proposed in the first aspect of the present invention includes a first DMS type filter and a second DMS type filter, wherein the first DMS type filter and the second DMS type filter are connected in parallel;

[0005] The first DMS type filter includes at least three first interdigital transducers spaced apart along a first direction. The at least three first interdigital transducers arranged in a row include a first middle interdigital transducer located in the middle and first end interdigital transducers located on both sides of the first middle interdigital transducer. Each first interdigital transducer includes a plurality of first electrode fingers. At least one first interdigital transducer includes a first part and a second part arranged along the first direction.

[0006] The second DMS type filter includes at least three second interdigital transducers spaced apart along the first direction. The at least three second interdigital transducers arranged in a row include a second middle interdigital transducer located in the middle and second end interdigital transducers located on both sides of the second middle interdigital transducer. Each second interdigital transducer includes a plurality of second electrode fingers. At least one second interdigital transducer includes a fourth part and a fifth part arranged along the first direction.

[0007] Wherein, the number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter is greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer is greater than the number of first electrode fingers in the second part; the number of second electrode fingers of at least one second end interdigital transducer of the second DMS type filter is less than the number of second electrode fingers of the second middle interdigital transducer, and the number of second electrode fingers in the fourth part of the second interdigital transducer is less than the number of second electrode fingers in the fifth part.

[0008] The filter proposed in the first aspect of this invention, by setting the number of first electrode fingers of at least one first end interdigital transducer of a first DMS-type filter to be greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer to be greater than the number of first electrode fingers in the second part, allows the filter to exhibit phase reversal at the edge of the passband, resulting in new transmission poles and thus widening the passband. Furthermore, due to the widened passband, the insertion loss at the edge of the passband is optimized within the operating frequency band. In addition, by connecting a second DMS-type filter in parallel, and setting the number of second electrode fingers of at least one second end interdigital transducer to be less than the number of second electrode fingers of the second middle interdigital transducer, and the number of second electrode fingers in the fourth part of the second interdigital transducer to be less than the number of second electrode fingers in the fifth part, the second DMS-type filter can compensate for the disadvantage of in-band insertion loss degradation in certain operating frequency bands in the middle of the passband of the first DMS-type filter. In other words, the first DMS filter widens the passband and compensates for the narrow passband of the second DMS filter. The second DMS filter, in turn, compensates for the in-band insertion loss degradation that occurs in certain operating frequency bands in the middle of the passband of the first DMS filter. The first and second DMS filters complement each other, so that the filter proposed in this application not only widens the passband but also optimizes the problems of in-band insertion loss degradation at the passband edges, enabling the filter to well meet the application requirements.

[0009] The filter proposed in the second aspect of the present invention includes a first DMS type filter, the first DMS type filter including at least three first interdigital transducers arranged at intervals along a first direction, the at least three first interdigital transducers arranged in a row including a first middle interdigital transducer located in the middle and first end interdigital transducers located on both sides of the first middle interdigital transducer.

[0010] Each of the first interdigital transducers includes a plurality of first electrode fingers, and at least one of the first interdigital transducers includes a first portion, a second portion, and a third portion arranged along the first direction;

[0011] Wherein, the number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter is greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer and / or the number of first electrode fingers in the third part is greater than the number of first electrode fingers in the second part.

[0012] The filter proposed in the second aspect of the present invention, by setting the number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter to be greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer to be greater than the number of first electrode fingers in the second part, enables the filter to exhibit phase reversal at the edge of the passband, resulting in new transmission poles, thereby widening the passband. Furthermore, due to the widened passband, the insertion loss at the edge of the passband is optimized within the operating frequency band.

[0013] The radio frequency module proposed in the third aspect of the present invention includes the filter described above.

[0014] The radio frequency module proposed in the third aspect of the present invention has the advantages of widening the passband and optimizing the degradation of insertion loss at the passband edge and within the band due to the use of the above-mentioned filter. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the filter structure proposed in an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of a first DMS-type filter proposed in an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of a second DMS-type filter proposed in an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of the structure of a first interdigital transducer proposed in an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the structure of a second interdigital transducer proposed in an embodiment of the present invention;

[0021] Figure 6 This is a schematic diagram of the structure of the first DMS type filter proposed in another embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram of the structure of a second DMS-type filter proposed in another embodiment of the present invention;

[0023] Figure 8 This is a passband characteristic curve of the first DMS type filter and the second DMS type filter proposed in an embodiment of the present invention.

[0024] Figure 9 This is a diagram showing the transmission response curve and admittance response curve of the first DMS type filter proposed in an embodiment of the present invention.

[0025] Figure 10 This is a comparison diagram of the transmission response of the first DMS type filter and the second DMS type filter proposed in an embodiment of the present invention;

[0026] Figure 11 This is a comparison diagram of the admittance response of a first DMS type filter and a second DMS type filter proposed in an embodiment of the present invention;

[0027] Figure 12 This is a passband characteristic curve of a filter in related technologies. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The following descriptions of the embodiments are based on the accompanying illustrations and are used to illustrate specific embodiments in which this application can be implemented. The component designations used herein, such as "first," "second," etc., are merely for distinguishing the described objects and do not have any sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages). Directional terms used in this application, such as "up," "down," "front," "rear," "left," "right," "inner," "outer," "side," etc., are merely for reference to the accompanying illustrations. Therefore, the use of directional terms is for better and clearer explanation and understanding of this application, and does not indicate or imply that the referred device or element must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as a limitation of this application.

[0030] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising," "may include," "include," or "may contain" used in this application indicate the existence of the corresponding disclosed functions, operations, elements, etc., and do not limit other one or more additional functions, operations, elements, etc.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0032] like Figures 1 to 5As shown, an embodiment of the present invention proposes a filter 100, which includes a first DMS type filter 10 and a second DMS type filter 20, wherein the first DMS type filter 10 and the second DMS type filter 20 are connected in parallel. The first DMS type filter 10 includes at least three first interdigital transducers 11 arranged at intervals along a first direction X. The at least three first interdigital transducers 11 arranged in a row include a first middle interdigital transducer 11b located in the middle and first end interdigital transducers 11a located on both sides of the first middle interdigital transducer 11b. Each first interdigital transducer 11 includes a plurality of first electrode fingers 111, and at least one first interdigital transducer 11 includes a first portion S1 and a second portion S2 arranged along the first direction X. The second DMS type filter 20 includes at least three second interdigital transducers 21 spaced apart along a first direction X. The at least three second interdigital transducers 21 arranged in a row include a second middle interdigital transducer 21b located in the middle and second end interdigital transducers 21a located on both sides of the second middle interdigital transducer 21b. Each second interdigital transducer 21 includes a plurality of second electrode fingers 211. At least one second interdigital transducer 21 includes a fourth portion S4 and a fifth portion S5 arranged along the first direction X. Specifically, the number of first electrode fingers 111 in at least one first end interdigital transducer 11a of the first DMS type filter 10 is greater than the number of first electrode fingers 111 in the first middle interdigital transducer 11b, and the number of first electrode fingers 111 in the first portion S1 of the first interdigital transducer 11 is greater than the number of first electrode fingers 111 in the second portion S2. The number of second electrode fingers 211 in at least one second end interdigital transducer 21a of the second DMS type filter 20 is less than the number of second first electrode fingers 111 in the second middle interdigital transducer 21b, and the number of second electrode fingers 211 in the fourth part S4 of the second interdigital transducer 21 is less than the number of second electrode fingers 211 in the fifth part S5.

[0033] In at least one embodiment, the DMS-type filter can be referred to as a longitudinally coupled surface acoustic wave (SAW) filter, including but not limited to a dual-mode surface acoustic wave (DMS) filter and a multi-mode SAW filter. The longitudinally coupled resonator includes a piezoelectric substrate, multiple interdigital transducers (IDTs), and two reflective gratings. The multiple interdigital transducers and reflective gratings are all located on the same side of the piezoelectric substrate, and the multiple interdigital transducers are arranged at intervals between the two reflective gratings.

[0034] In at least one embodiment, the piezoelectric substrate of the longitudinally coupled resonator may include a piezoelectric layer, which may be a single layer or multiple layers of piezoelectric materials with piezoelectric properties, such as aluminum nitride, zinc oxide, lead zirconate titanate (PZT) or rare earth element doped materials of a certain atomic ratio of the above materials; or a single crystal piezoelectric material may be selected, such as single crystal aluminum nitride, lithium niobate, lithium tantalate, quartz, etc., which is not limited in this embodiment.

[0035] The interdigital transducer and the reflective grid can be made of a single metal material or a composite or alloy of different metals. Optionally, the material can be one of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, or a composite or alloy of these metals. The materials of the interdigital transducer and the reflective grid can be the same or different. The interdigital transducer and the reflective grid can be a single-layer metal film or a stacked metal film with multiple metal layers. This application does not limit the specific embodiments.

[0036] The filter 100 proposed in this embodiment sets the number of first electrode fingers 111 of at least one first end interdigital transducer 11a of the first DMS type filter 10 to be greater than the number of first electrode fingers 111 of the first middle interdigital transducer 11b, and the number of first electrode fingers 111 in the first part S1 of the first interdigital transducer 11 is greater than the number of first electrode fingers 111 in the second part S2. With this implementation, the filter 100 can have a phase flip at the edge of the passband, resulting in a new transmission pole, thereby widening the passband. Furthermore, due to the widened passband, the insertion loss at the edge of the passband is optimized within the operating frequency band. Furthermore, by connecting a second DMS-type filter 20 in parallel, and by configuring the second DMS-type filter 20 to have a smaller number of second electrode fingers 211 in at least one second end interdigital transducer 21a than the number of second electrode fingers 211 in the second middle interdigital transducer 21b, and by configuring the second interdigital transducer 21 to have a smaller number of second electrode fingers 211 in the fourth part S4 than the number of second electrode fingers 211 in the fifth part S5, the second DMS-type filter 20 can compensate for the disadvantage of the first DMS-type filter 10 having deteriorated in-band insertion loss in certain operating frequency bands in the middle of the passband. In other words, the first DMS filter 10 widens the passband, compensating for the narrow passband of the second DMS filter 20. The second DMS filter 20, in turn, compensates for the in-band insertion loss degradation that occurs in certain operating frequency bands in the middle of the passband of the first DMS filter 10. The first DMS filter 10 and the second DMS filter 20 complement each other, enabling the filter 100 proposed in this application to both widen the passband and optimize the problems of in-band insertion loss degradation at the passband edges, thus allowing the filter 100 to well meet the application requirements.

[0037] Figure 8The diagram shows the passband characteristic curves of the first DMS type filter 10 and the second DMS type filter 20. The solid line represents the passband characteristic curve of the first DMS type filter 10, and the dashed line represents the passband characteristic curve of the second DMS type filter 20. Figure 8 It can be seen that the passband characteristic curve of the first DMS type filter 10 shows phase reversal at the edge.

[0038] Figure 9 The diagram shows the transmission response curve and admittance response curve of the first DMS type filter 10. The solid line represents the transmission response curve of the first DMS type filter 10, and the dashed line represents the admittance response curve of the first DMS type filter 10. Figure 9 It can be seen that the first DMS type filter 10 has new transmission poles at the edges of both sides of the passband.

[0039] Figure 10 The diagram shows a comparison of the transmission responses of the first DMS type filter 10 and the second DMS type filter 20. The solid line represents the transmission response curve of the first DMS type filter 10, and the dashed line represents the transmission response curve of the second DMS type filter 20. Figure 11 This displays a comparison of the admittance responses of the first DMS type filter 10 and the second DMS type filter 20. The solid line represents the admittance response curve of the first DMS type filter 10, and the dashed line represents the admittance response curve of the second DMS type filter 20. Figure 10 and Figure 11 It can be seen that the first DMS filter 10 exhibits the disadvantage of deteriorated in-band insertion loss in the 770MHz-790MHz operating frequency band, but the second DMS filter 20 has a smaller insertion loss in the 770MHz-790MHz operating frequency band. The combination of the two can compensate for the disadvantage of deteriorated in-band insertion loss of the first DMS filter 10 in the 770MHz-790MHz operating frequency band.

[0040] Figure 12 The diagram shows the passband characteristic curve of filter 100 in the related technology, which has an in-band insertion loss of 1.5dB in the 758MHz to 803MHz operating frequency band. In contrast, the filter 100 proposed in this application can achieve an in-band insertion loss of 1.3dB in the 758MHz to 803MHz operating frequency band.

[0041] It should be noted that although the above embodiments only mention that the filter 100 includes a first DMS type filter 10 and a second DMS type filter 20 connected in parallel, it is not limited to the filter 100 including only the first DMS type filter 10 and the second DMS type filter 20. For example, in some other embodiments, the filter 100 may also be configured to include three, four or more DMS type filters connected in parallel, as long as two of the DMS type filters satisfy the above-described implementation of the first DMS type filter 10 and the second DMS type filter 20.

[0042] like Figure 2 As shown, in some embodiments, the first DMS type filter 10 includes an odd number of first interdigital transducers 11 arranged in a row, with the first interdigital transducer 11 located in the middle being the first middle interdigital transducer 11b, and the remaining first interdigital transducers 11 being the first end interdigital transducers 11a.

[0043] like Figure 2 As shown, in some embodiments, the first DMS type filter 10 includes an odd number of first interdigital transducers 11 arranged in a row. The first central interdigital transducer 11b includes a first side and a second side. The first interdigital transducers 11 on the first side and the first interdigital transducers 11 on the second side are symmetrically arranged with the first central interdigital transducer 11b as the dividing point. The two symmetrically arranged first interdigital transducers 11 have identical structural parameters, including, but not limited to, the number of first interdigital fingers 111, DF (duty cycle, the ratio of the width of a first interdigital finger 111 in a certain region to the distance between the centerlines of two adjacent first interdigital fingers 111), and pitch (the distance between the centerlines of two adjacent first interdigital fingers 111). The first direction is the direction of sound propagation in the filter.

[0044] For example, in a specific embodiment, such as Figure 2 As shown, the first DMS type filter 10 includes five first interdigital transducers 11. The five first interdigital transducers 11 are A1 interdigital transducer, A2 interdigital transducer, A3 interdigital transducer, A4 interdigital transducer, and A5 interdigital transducer along the first direction X. A3 interdigital transducer is the first middle interdigital transducer, and A1, A2, A4, and A5 interdigital transducers are the first end interdigital transducers 11a. A1 and A5 interdigital transducers are symmetrically arranged, and A2 and A4 interdigital transducers are symmetrically arranged.

[0045] In some embodiments, the structural parameters of the A2 interdigital transducer are the same as those of the A4 interdigital transducer, and both are different from the structural parameters of the A3 interdigital transducer. In other embodiments, the structural parameters of the A1 interdigital transducer, the A2 interdigital transducer, the A4 interdigital transducer, and the A5 interdigital transducer are all the same.

[0046] It should be noted that the number of first interdigital transducers 11 in the first DMS type filter 10 is not limited to an odd number. For example, in some other embodiments, such as Figure 6 As shown, the first DMS type filter 10 includes an even number of first interdigital transducers 11 arranged in a row. The two first interdigital transducers 11 located in the middle are the first middle interdigital transducers 11b, and the remaining first interdigital transducers 11 are the first end interdigital transducers 11a.

[0047] In some embodiments, the first DMS type filter 10 includes an even number of first interdigital transducers 11 arranged in a row. The first DMS type filter 10 has a central axis that divides the even number of first interdigital transducers 11 into two groups of the same number of first interdigital transducers 11. The two groups of first interdigital transducers 11 are symmetrically arranged with the central axis as the dividing point.

[0048] For example, in a specific embodiment, such as Figure 6 As shown, the first DMS type filter 10 includes six first interdigital transducers 11. The six first interdigital transducers 11 are A1 interdigital transducer, A2 interdigital transducer, A3 interdigital transducer, A4 interdigital transducer, A5 interdigital transducer, and A6 interdigital transducer along the first direction X. Interdigital transducers A3 and A4 are first middle interdigital transducers 11b, and interdigital transducers A1, A2, A5, and A6 are first end interdigital transducers 11a. Interdigital transducers A1 and A6 are symmetrically arranged, interdigital transducers A2 and A5 are symmetrically arranged, and interdigital transducers A3 and A4 are symmetrically arranged.

[0049] In some embodiments, the structural parameters of the A1 interdigital transducer are different from those of the A2 interdigital transducer. In other embodiments, the structural parameters of the A1 interdigital transducer are the same as those of the A2 interdigital transducer.

[0050] In the above embodiments, by symmetrically arranging the first interdigital transducers 11 of the first DMS-type filter 10, the filter 100 has the following advantages: First, it can better control the propagation direction and intensity of surface acoustic waves, thereby enhancing the frequency selectivity of the filter 100. Second, it can reduce the influence of interference and stray signals, thereby improving the performance stability of the filter 100. Third, it can improve the conversion efficiency between electrical signals and acoustic signals. Fourth, it can improve the performance indicators of the filter 100, such as improving the insertion loss and return loss of the filter 100.

[0051] It should be noted that the first interdigital transducer 11 of the first DMS type filter 10 is not limited to the above-described symmetrical arrangement. For example, in some other embodiments, the first interdigital transducer 11 of the first DMS type filter 10 can also be arranged asymmetrically, as long as the number of first electrode fingers 111 of the first middle interdigital transducer 11b of the first DMS type filter 10 is greater than the number of first electrode fingers 111 of at least one first end interdigital transducer 11a, and the number of first electrode fingers 111 in the first part S1 of the first interdigital transducer 11 is greater than the number of first electrode fingers 111 in the second part S2. The specific arrangement can be determined according to the actual design requirements.

[0052] In some embodiments, the number of first electrode fingers 111 of the A3 interdigital transducer is less than the number of first electrode fingers 111 of the A2 interdigital transducer, and the number of first electrode fingers 111 of the A2 interdigital transducer is less than the number of first electrode fingers 111 of the A1 interdigital transducer. That is, among the five first interdigital transducers 11 of the first DMS type filter 10, the number of first electrode fingers 111 in the middle first interdigital transducer 11 is the least, and then the number of first electrode fingers 111 gradually increases towards the two sides of the first interdigital transducer 11.

[0053] In some other embodiments, the number of first electrode fingers 111 of the A3 interdigital transducer is less than the number of first electrode fingers 111 of the A2 interdigital transducer, and the number of first electrode fingers 111 of the A2 interdigital transducer is equal to the number of first electrode fingers 111 of the A1 interdigital transducer.

[0054] like Figure 4 As shown, in some embodiments, the distance between the midlines of two adjacent first electrode fingers 111 in the first part S1 is smaller than the distance between the midlines of two adjacent first electrode fingers 111 in the second part S2. This implementation can broaden the passband of the filter 100 and improve its out-of-band suppression performance.

[0055] like Figure 4As shown, in some embodiments, the first interdigital transducer 11 includes a first part S1, a second part S2 and a third part S3, the first part S1, the second part S2 and the third part S3 are arranged along a first direction X, and the number of first electrode fingers 111 in the third part S3 is greater than the number of first electrode fingers 111 in the second part S2.

[0056] In some embodiments, the first portion S1 and the third portion S3 of the first interdigital transducer 11 are symmetrically arranged. This implementation allows for better control of the propagation direction and intensity of the surface acoustic wave, thereby enhancing the frequency selectivity of the filter 100; it can reduce the influence of interference and stray signals, thereby improving the performance stability of the filter 100; it can improve the conversion efficiency between electrical and acoustic signals; and it can improve the performance indicators of the filter 100, such as improving the insertion loss and return loss of the filter 100.

[0057] It should be noted that the first part S1 and the third part S3 of the first interdigital transducer 11 are not limited to being symmetrically arranged as described above. For example, in some other embodiments, the first part S1 and the third part S3 of the first interdigital transducer 11 can also be asymmetrically arranged, as long as the number of first electrode fingers 111 in the first part S1 is greater than the number of first electrode fingers 111 in the second part S2, and the number of first electrode fingers 111 in the third part S3 is greater than the number of first electrode fingers 111 in the second part S2. The specific arrangement can be determined according to the actual design requirements.

[0058] like Figure 4 As shown, in some embodiments, the distance between the midlines of two adjacent first electrode fingers 111 in the third part S3 is less than the distance between the midlines of two adjacent first electrode fingers 111 in the second part S2. This implementation can broaden the passband of the filter 100 and improve its out-of-band suppression performance.

[0059] In some embodiments, the first DMS type filter 10 includes an odd number of first interdigital transducers 11 arranged in a row, with only the middle first interdigital transducer 11 including a first portion S1, a second portion S2, and a third portion S3. This implementation allows the first DMS type filter 10 to achieve better symmetry.

[0060] In some embodiments, the first DMS type filter 10 includes an even number of first interdigital transducers 11 arranged in a row, with only the two middle first interdigital transducers 11 comprising a first portion S1, a second portion S2, and a third portion S3. This implementation allows the first DMS type filter 10 to achieve better symmetry.

[0061] In some embodiments, all the first interdigital transducers 11 of the first DMS type filter 10 include a first portion S1, a second portion S2, and a third portion S3.

[0062] It should be noted that although the above embodiments only mention that at least one first interdigital transducer 11 includes a first portion S1 and a second portion S2 arranged along the first direction X, or includes a first portion S1, a second portion S2, and a third portion S3 arranged along the first direction X, it is not limited to the first interdigital transducer 11 only including the first portion S1 and the second portion S2, or only including the first portion S1, the second portion S2, and the third portion S3. For example, in some other embodiments, the first interdigital transducer 11 may also be configured to include four, five, or more portions, as long as two or three of the portions satisfy the above-described implementation of the first portion S1 and the second portion S2, or the above-described implementation of the first portion S1, the second portion S2, and the third portion S3.

[0063] In some embodiments, the number of first electrode fingers 111 of the first central interdigital transducer 11b of the first DMS type filter 10 ranges from [20, 60]. Further, in some embodiments, the number of first electrode fingers 111 of the first central interdigital transducer 11b of the first DMS type filter 10 ranges from [30, 50]. Specifically, the number of first electrode fingers 111 of the first central interdigital transducer 11b of the first DMS type filter 10 can be set to any one of 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50.

[0064] In some embodiments, the number of first electrode fingers 111 of the first end interdigital transducer 11a of the first DMS type filter 10 ranges from [10, 50]. Further, in some embodiments, the number of first electrode fingers 111 of the first end interdigital transducer 11a of the first DMS type filter 10 ranges from [20, 40]. Specifically, the number of first electrode fingers 111 of the first end interdigital transducer 11a of the first DMS type filter 10 can be set to any one of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40.

[0065] In some embodiments, the number of first electrode fingers 111 in the first portion S1 of the first interdigital transducer 11 ranges from [10, 30]. Further, in some embodiments, the number of first electrode fingers 111 in the first portion S1 of the first interdigital transducer 11 ranges from [15, 25]. Specifically, the number of first electrode fingers 111 in the first portion S1 of the first interdigital transducer 11 can be set to any one of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25.

[0066] In some embodiments, the number of first electrode fingers 111 in the second portion S2 of the first interdigital transducer 11 ranges from [5, 20]. Further, in some embodiments, the number of first electrode fingers 111 in the second portion S2 of the first interdigital transducer 11 ranges from [10, 15]. Specifically, the number of first electrode fingers 111 in the second portion S2 of the first interdigital transducer 11 can be set to any one of 10, 11, 12, 13, 14, and 15.

[0067] In some embodiments, the first DMS type filter 10 further includes two spaced first reflective gratings 12, and at least three first interdigital transducers 11 are located between the two first reflective gratings 12.

[0068] like Figure 3 As shown, in some embodiments, the second DMS type filter 20 includes an odd number of second interdigital transducers 21 arranged in a row, with the middle second interdigital transducer 21 being the second middle interdigital transducer 21b, and the remaining second interdigital transducers 21 being the second end interdigital transducers 21a.

[0069] like Figure 3 As shown, in some embodiments, the second DMS type filter 20 includes an odd number of second interdigital transducers 21 arranged in a row. The second middle interdigital transducer 21b includes a third side and a fourth side. The second interdigital transducers 21 located on the third side and the second interdigital transducers 21 located on the fourth side are symmetrically arranged with the second middle interdigital transducer 21b as the dividing point. The two symmetrically arranged second interdigital transducers 21 have the same structural parameters, including but not limited to the number of second electrode fingers 211, DF (duty cycle), and pitch / 2 (pitch refers to the distance between the centerlines of two adjacent second electrode fingers 211).

[0070] For example, in a specific embodiment, such as Figure 3As shown, the second DMS type filter 20 includes five second interdigital transducers 21. Along the first direction X, the five second interdigital transducers 21 are designated as B1 interdigital transducer, B2 interdigital transducer, B3 interdigital transducer, B4 interdigital transducer, and B5 interdigital transducer. B3 interdigital transducer is the second middle interdigital transducer 21b, and B1, B2, B4, and B5 interdigital transducers are the second end interdigital transducers 21a. The B1 and B5 interdigital transducers are symmetrically arranged, as are the B2 and B4 interdigital transducers.

[0071] In some embodiments, the structural parameters of the B2 interdigital transducer are the same as those of the B4 interdigital transducer, and both are different from the structural parameters of the B3 interdigital transducer. In other embodiments, the structural parameters of the B1 interdigital transducer, the B2 interdigital transducer, the B4 interdigital transducer, and the B5 interdigital transducer are all the same.

[0072] It should be noted that the number of second interdigital transducers 21 in the second DMS type filter 20 is not limited to an odd number. For example, in some other embodiments, such as Figure 7 As shown, the second DMS type filter 20 includes an even number of second interdigital transducers 21 arranged in a row. The two second interdigital transducers 21 located in the middle are the second middle interdigital transducers 21b, and the remaining second interdigital transducers 21 are the second end interdigital transducers 21a.

[0073] In some embodiments, the second DMS type filter 20 includes an even number of second interdigital transducers 21 arranged in a row. The second DMS type filter 20 has a central axis that divides the even number of second interdigital transducers 21 into two groups of the same number of second interdigital transducers 21. The two groups of second interdigital transducers 21 are symmetrically arranged with the central axis as the dividing point.

[0074] For example, in a specific embodiment, such as Figure 7 As shown, the second DMS type filter 20 includes six second interdigital transducers 21. Along the first direction X, the six second interdigital transducers 21 are designated as B1 interdigital transducer, B2 interdigital transducer, B3 interdigital transducer, B4 interdigital transducer, B5 interdigital transducer, and B6 interdigital transducer. B3 and B4 interdigital transducers are second middle interdigital transducers 21b, and B1, B2, B5, and B6 interdigital transducers are second end interdigital transducers 21a. The B1 and B6 interdigital transducers are symmetrically arranged, as are the B2 and B5 interdigital transducers, and the B3 and B4 interdigital transducers.

[0075] In some embodiments, the structural parameters of the interdigital transducer B1 are different from those of the interdigital transducer B2. In other embodiments, the structural parameters of the interdigital transducer B1 are the same as those of the interdigital transducer B2.

[0076] In the two embodiments described above, by symmetrically arranging the second interdigital transducers 21 of the second DMS-type filter 20, the filter 100 possesses the following advantages: First, it can better control the propagation direction and intensity of surface acoustic waves, thereby enhancing the frequency selectivity of the filter 100. Second, it can reduce the influence of interference and stray signals, thereby improving the performance stability of the filter 100. Third, it can improve the conversion efficiency between electrical and acoustic signals. Fourth, it can improve the performance indicators of the filter 100, such as improving the insertion loss and return loss of the filter 100.

[0077] It should be noted that the second interdigital transducer 21 of the second DMS type filter 20 is not limited to the above-described symmetrical arrangement. For example, in some other embodiments, the second interdigital transducer 21 of the second DMS type filter 20 can also be arranged asymmetrically, as long as the number of second electrode fingers 211 of the second middle interdigital transducer 21b of the second DMS type filter 20 is less than the number of second electrode fingers 211 of at least one second end interdigital transducer 21a, and the number of second electrode fingers 211 in the fourth part S4 of the second interdigital transducer 21 is less than the number of second electrode fingers 211 in the fifth part S5. The specific arrangement can be determined according to the actual design requirements.

[0078] In some embodiments, the number of second electrode fingers 211 of the B3 interdigital transducer is greater than the number of second electrode fingers 211 of the B2 interdigital transducer, and the number of second electrode fingers 211 of the B2 interdigital transducer is greater than the number of second electrode fingers 211 of the B1 interdigital transducer. That is, among the five second interdigital transducers 21 of the second DMS type filter 20, the middle second interdigital transducer 21 has the most second electrode fingers 211, and then the number of second electrode fingers 211 gradually decreases towards the two sides.

[0079] In some other embodiments, the number of second electrode fingers 211 of the B3 interdigital transducer is greater than the number of second electrode fingers 211 of the B2 interdigital transducer, and the number of second electrode fingers 211 of the B2 interdigital transducer is equal to the number of second electrode fingers 211 of the B1 interdigital transducer.

[0080] like Figure 5As shown, in some embodiments, the distance between the midlines of two adjacent second electrode fingers 211 in the fourth part S4 is less than the distance between the midlines of two adjacent second electrode fingers 211 in the fifth part S5. This implementation can broaden the passband of the filter 100 and improve its out-of-band suppression performance.

[0081] like Figure 5 As shown, in some embodiments, the second interdigital transducer 21, which includes the fourth part S4 and the fifth part S5, also includes a sixth part S6. The fourth part S4, the fifth part S5 and the sixth part S6 are arranged along the first direction X. The number of second electrode fingers 211 in the sixth part S6 is less than the number of second electrode fingers 211 in the fifth part S5.

[0082] In some embodiments, the fourth portion S4 and the sixth portion S6 of the second interdigital transducer 21 are symmetrically arranged. This implementation allows for better control of the propagation direction and intensity of the surface acoustic wave, thereby enhancing the frequency selectivity of the filter 100; it can reduce the influence of interference and stray signals, thereby improving the performance stability of the filter 100; it can improve the conversion efficiency between electrical and acoustic signals; and it can improve the performance indicators of the filter 100, such as improving the insertion loss and return loss of the filter 100.

[0083] It should be noted that the fourth part S4 and the sixth part S6 of the second interdigital transducer 21 are not limited to being symmetrically arranged as described above. For example, in some other embodiments, the fourth part S4 and the sixth part S6 of the second interdigital transducer 21 can also be asymmetrically arranged, as long as the number of second electrode fingers 211 in the fourth part S4 is less than the number of second electrode fingers 211 in the fifth part S5, and the number of second electrode fingers 211 in the sixth part S6 is less than the number of second electrode fingers 211 in the fifth part S5. The specific arrangement can be determined according to the actual design requirements.

[0084] like Figure 5 As shown, in some embodiments, the distance between the midlines of two adjacent second electrode fingers 211 in the sixth part S6 is less than the distance between the midlines of two adjacent second electrode fingers 211 in the fifth part S5. This implementation can broaden the passband of the filter 100 and improve its out-of-band suppression.

[0085] In some embodiments, the second DMS-type filter 20 includes an odd number of second interdigital transducers 21 arranged in a row, with only the middle second interdigital transducer 21 including a fourth portion S4, a fifth portion S5, and a sixth portion S6. This implementation allows the second DMS-type filter 20 to achieve better symmetry.

[0086] In some embodiments, the second DMS-type filter 20 includes an even number of second interdigital transducers 21 arranged in a row, with only the two middle second interdigital transducers 21 comprising a fourth portion S4, a fifth portion S5, and a sixth portion S6. This implementation allows the second DMS-type filter 20 to achieve better symmetry.

[0087] In some embodiments, all the second interdigital transducers 21 of the second DMS type filter 20 include a fourth part S4, a fifth part S5, and a sixth part S6.

[0088] It should be noted that although the above embodiments only mention that at least one second interdigital transducer 21 includes a fourth portion S4 and a fifth portion S5 arranged along the first direction X, or includes a fourth portion S4, a fifth portion S5, and a sixth portion S6 arranged along the first direction X, it is not limited to the second interdigital transducer 21 only including the fourth portion S4 and the fifth portion S5, or only including the fourth portion S4, the fifth portion S5, and the sixth portion S6. For example, in some other embodiments, the second interdigital transducer 21 may also be configured to include four, five, or more portions, as long as two or three of the portions satisfy the above-described implementation of the fourth portion S4 and the fifth portion S5, or the above-described implementation of the fourth portion S4, the fifth portion S5, and the sixth portion S6.

[0089] In some embodiments, the number of second electrode fingers 211 of the second interdigital transducer 21b of the second DMS type filter 20 ranges from [15, 45]. Further, in some embodiments, the number of second electrode fingers 211 of the second interdigital transducer 21b of the second DMS type filter 20 ranges from [20, 40]. Specifically, the number of second electrode fingers 211 of the second interdigital transducer 21b of the second DMS type filter 20 can be set to any one of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40.

[0090] In some embodiments, the number of second electrode fingers 211 of the second end interdigital transducer 21a of the second DMS type filter 20 ranges from [20, 60]. Further, in some embodiments, the number of second electrode fingers 211 of the second end interdigital transducer 21a of the second DMS type filter 20 ranges from [30, 50]. Specifically, the number of second electrode fingers 211 of the second end interdigital transducer 21a of the second DMS type filter 20 can be set to any one of 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50.

[0091] In some embodiments, the number of second electrode fingers 211 in the fourth portion S4 of the second interdigital transducer 21 ranges from [3, 15]. Further, in some embodiments, the number of second electrode fingers 211 in the fourth portion S4 of the second interdigital transducer 21 ranges from [5, 10]. Specifically, the number of second electrode fingers 211 in the fourth portion S4 of the second interdigital transducer 21 can be set to any one of 5, 6, 7, 8, 9, and 10.

[0092] In some embodiments, the number of second electrode fingers 211 in the fifth portion S5 of the second interdigital transducer 21 ranges from [10, 30]. Further, in some embodiments, the number of second electrode fingers 211 in the fifth portion S5 of the second interdigital transducer 21 ranges from [15, 25]. Specifically, the number of second electrode fingers 211 in the fifth portion S5 of the second interdigital transducer 21 can be set to any one of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25.

[0093] In some embodiments, the second DMS type filter 20 further includes two spaced second reflective gratings 22, and at least three second interdigital transducers 21 are located between the two second reflective gratings 22.

[0094] like Figure 1 As shown, in some embodiments, filter 100 further includes an input node IN and an output node OUT, with the first DMS filter 100 connected between the input node IN and the output node OUT. Filter 100 also includes a first resonator 30, one port of which is connected to the line between the input node IN and the first DMS filter 100, and the other port of the first resonator 30 is grounded.

[0095] like Figure 1 As shown, in some embodiments, the filter 100 further includes a second resonator 40, one port of which is connected to the line between the output node OUT and the first DMS filter 100, and the other port of the second resonator 40 is grounded.

[0096] The first resonator 30 and the second resonator 40 are used for left-side passband suppression.

[0097] In some embodiments, filter 100 is a receiving filter.

[0098] In some embodiments, the filter 100 operates in a frequency band between 758 MHz and 803 MHz.

[0099] like Figure 1 , Figure 2 and Figure 4 As shown, an embodiment of the present invention also proposes a filter 100, which includes a first DMS type filter 10. The first DMS type filter 10 includes at least three first interdigital transducers 11 arranged at intervals along a first direction X. The at least three first interdigital transducers 11 arranged in a row include a first middle interdigital transducer 11b located in the middle and first end interdigital transducers 11a located on both sides of the first middle interdigital transducer 11b. Each first interdigital transducer 11 includes a plurality of first electrode fingers 111, and at least one first interdigital transducer 11 includes a first portion S1, a second portion S2, and a third portion S3 arranged along the first direction X. In this first DMS type filter 10, the number of first electrode fingers 111 of at least one first end interdigital transducer 11a is greater than the number of first electrode fingers 111 of the first middle interdigital transducer 11b, and the number of first electrode fingers 111 in the first part S1 and / or the number of first electrode fingers 111 in the third part S3 of the first interdigital transducer 11 is greater than the number of first electrode fingers 111 in the second part S2.

[0100] The filter 100 proposed in this embodiment sets the number of first electrode fingers 111 of at least one first end interdigital transducer 11a of the first DMS type filter 10 to be greater than the number of first electrode fingers 111 of the first middle interdigital transducer 11b, and the number of first electrode fingers 111 in the first part S1 of the first interdigital transducer 11 is greater than the number of first electrode fingers 111 in the second part S2. With this implementation, the filter 100 can have a phase flip at the edge of the passband, resulting in a new transmission pole, thereby widening the passband. Furthermore, due to the widened passband, the insertion loss at the edge of the passband is optimized within the operating frequency band.

[0101] like Figure 2As shown, in some embodiments, the first DMS type filter 10 includes an odd number of first interdigital transducers 11 arranged in a row. The first interdigital transducer 11 located in the middle is the first middle interdigital transducer 11b, and the remaining first interdigital transducers 11 are the first end interdigital transducers 11a. The first middle interdigital transducer 11b includes a first side and a second side. The first interdigital transducers 11 located on the first side and the first interdigital transducers 11 located on the second side are symmetrically arranged with the first middle interdigital transducer 11b as the dividing point.

[0102] like Figure 2 As shown, in some embodiments, the first DMS type filter 10 includes five first interdigital transducers 11. The five first interdigital transducers 11 are designated A1, A2, A3, A4, and A5 interdigital transducers along a first direction X. A3 is a first middle interdigital transducer 11b, and A1, A2, A4, and A5 are first end interdigital transducers 11a. The structural parameters of A1 and A5 interdigital transducers are identical, and the structural parameters of A2 and A4 interdigital transducers are identical, but all differ from the structural parameters of A3 interdigital transducers.

[0103] like Figure 6 As shown, in some embodiments, the first DMS type filter 10 includes an even number of first interdigital transducers 11 arranged in a row. The two first interdigital transducers 11 located in the middle are the first middle interdigital transducers 11b, and the remaining first interdigital transducers 11 are the first end interdigital transducers 11a. The first DMS type filter 10 has a central axis, which divides the even number of first interdigital transducers 11 into two groups of the same number of first interdigital transducers 11. The two groups of first interdigital transducers 11 are symmetrically arranged with the central axis as the dividing point.

[0104] like Figure 4 As shown, in some embodiments, the distance between the midlines of two adjacent first electrode fingers 111 in the first part S1 is less than the distance between the midlines of two adjacent first electrode fingers 111 in the second part S2.

[0105] like Figure 4 As shown, in some embodiments, the distance between the midlines of two adjacent first electrode fingers 111 in the third part S3 is less than the distance between the midlines of two adjacent first electrode fingers 111 in the second part S2.

[0106] like Figure 1 , Figure 3 and Figure 5As shown, in some embodiments, the filter 100 further includes a second DMS-type filter 20, which is connected in parallel with the first DMS-type filter 10. The second DMS-type filter 20 includes at least three second interdigital transducers 21 arranged at intervals along a first direction X. The at least three second interdigital transducers 21 arranged in a row include a second middle interdigital transducer 21b located in the middle and second end interdigital transducers 21a located on both sides of the second middle interdigital transducer 21b. Each second interdigital transducer 21 includes a plurality of second electrode fingers 211, and at least one second interdigital transducer 21 includes a fourth portion S4, a fifth portion S5, and a sixth portion S6 arranged along the first direction X. In this process, the number of second electrode fingers 211 in at least one second end interdigital transducer 21a of the second DMS type filter 20 is less than the number of second electrode fingers 211 in the second middle interdigital transducer 21b, and the number of second electrode fingers 211 in the fourth part S4 and / or the sixth part S6 of the second interdigital transducer 21 is less than the number of second electrode fingers 211 in the fifth part S5.

[0107] like Figure 3 As shown, in some embodiments, the second DMS type filter 20 includes an odd number of second interdigital transducers 21 arranged in a row. The second interdigital transducer 21 located in the middle is the second middle interdigital transducer 21b, and the remaining second interdigital transducers 21 are the second end interdigital transducers 21a. The second middle interdigital transducer 21b includes a third side and a fourth side. The second interdigital transducer 21 located on the third side and the second interdigital transducer 21 located on the fourth side are symmetrically arranged with the second middle interdigital transducer 21b as the dividing point.

[0108] like Figure 3 As shown, in some embodiments, the second DMS type filter 20 includes five second interdigital transducers 21. The five second interdigital transducers 21 are designated as B1 interdigital transducer, B2 interdigital transducer, B3 interdigital transducer, B4 interdigital transducer, and B5 interdigital transducer along the first direction X. B3 interdigital transducer is a second middle interdigital transducer 21b, and B1, B2, B4, and B5 interdigital transducers are second end interdigital transducers 21a. The structural parameters of interdigital transducers B1 and B5 are identical, and the structural parameters of interdigital transducers B2 and B4 are identical, but all differ from the structural parameters of interdigital transducer B3.

[0109] like Figure 7As shown, in some embodiments, the second DMS type filter 20 includes an even number of second interdigital transducers 21 arranged in a row. The two second interdigital transducers 21 located in the middle are the second middle interdigital transducers 21b, and the remaining second interdigital transducers 21 are the second end interdigital transducers 21a. The second DMS type filter 20 has a central axis, which divides the even number of second interdigital transducers 21 into two groups of the same number of second interdigital transducers 21. The two groups of second interdigital transducers 21 are symmetrically arranged with the central axis as the dividing point.

[0110] like Figure 5 As shown, in some embodiments, the distance between the midlines of two adjacent second electrode fingers 211 in the fourth part S4 is less than the distance between the midlines of two adjacent second electrode fingers 211 in the fifth part S5.

[0111] like Figure 5 As shown, in some embodiments, the distance between the midlines of two adjacent second electrode fingers 211 in the sixth part S6 is less than the distance between the midlines of two adjacent second electrode fingers 211 in the fifth part S5.

[0112] The structure, connection relationship, extended description and beneficial effects of other components of the filter 100 proposed in this embodiment can be referred to the above text, and will not be repeated here.

[0113] An embodiment of the present invention also provides a radio frequency module, which includes the filter 100 described above.

[0114] The RF module proposed in this embodiment, due to the use of the aforementioned filter 100, has the advantages of widening the passband and optimizing the degradation of insertion loss at the passband edge and within the band.

[0115] The structure, connection relationship, extended description and beneficial effects of other components of the radio frequency module proposed in this embodiment can be referred to above, and will not be repeated here.

[0116] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A filter, characterized in that, It includes a first DMS type filter and a second DMS type filter, wherein the first DMS type filter and the second DMS type filter are connected in parallel; The first DMS type filter includes at least three first interdigital transducers spaced apart along a first direction. The at least three first interdigital transducers arranged in a row include a first middle interdigital transducer located in the middle and first end interdigital transducers located on both sides of the first middle interdigital transducer. Each first interdigital transducer includes a plurality of first electrode fingers. At least one first interdigital transducer includes a first part and a second part arranged along the first direction. The second DMS type filter includes at least three second interdigital transducers spaced apart along the first direction. The at least three second interdigital transducers arranged in a row include a second middle interdigital transducer located in the middle and second end interdigital transducers located on both sides of the second middle interdigital transducer. Each second interdigital transducer includes a plurality of second electrode fingers. At least one second interdigital transducer includes a fourth part and a fifth part arranged along the first direction. Wherein, the number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter is greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer is greater than the number of first electrode fingers in the second part; the number of second electrode fingers of at least one second end interdigital transducer of the second DMS type filter is less than the number of second electrode fingers of the second middle interdigital transducer, and the number of second electrode fingers in the fourth part of the second interdigital transducer is less than the number of second electrode fingers in the fifth part.

2. The filter as described in claim 1, characterized in that, The first DMS type filter includes an odd number of first interdigital transducers arranged in rows, with the first interdigital transducer located in the middle being the first middle interdigital transducer, and the remaining first interdigital transducers being the first end interdigital transducers; or, the first DMS type filter includes an even number of first interdigital transducers arranged in rows, with the two first interdigital transducers located in the middle being the first middle interdigital transducers, and the remaining first interdigital transducers being the first end interdigital transducers; And / or, The second DMS type filter includes an odd number of second interdigital transducers arranged in rows, with the middle second interdigital transducer being the second middle interdigital transducer and the remaining second interdigital transducers being the second end interdigital transducers; or, the second DMS type filter includes an even number of second interdigital transducers arranged in rows, with the two middle second interdigital transducers being the second middle interdigital transducers and the remaining second interdigital transducers being the second end interdigital transducers.

3. The filter as described in claim 2, characterized in that, The first DMS type filter includes an odd number of first interdigital transducers arranged in rows. The first middle interdigital transducer includes a first side and a second side. The first interdigital transducers located on the first side and the first interdigital transducers located on the second side are symmetrically arranged with the first middle interdigital transducer as the dividing point. Alternatively, the first DMS type filter includes an even number of first interdigital transducers arranged in rows. The first DMS type filter has a central axis. The central axis divides the even number of first interdigital transducers into two groups of the same number of first interdigital transducers. The two groups of first interdigital transducers are symmetrically arranged with the central axis as the dividing point. And / or, The second DMS type filter includes an odd number of second interdigital transducers arranged in rows, with the middle second interdigital transducer being the second middle interdigital transducer and the remaining second interdigital transducers being the second end interdigital transducers; or, the second DMS type filter includes an even number of second interdigital transducers arranged in rows, with the two middle second interdigital transducers being the second middle interdigital transducers and the remaining second interdigital transducers being the second end interdigital transducers.

4. The filter as described in claim 1, characterized in that, The first DMS type filter includes five first interdigital transducers, which are designated as A1 interdigital transducer, A2 interdigital transducer, A3 interdigital transducer, A4 interdigital transducer, and A5 interdigital transducer along the first direction. The A3 interdigital transducer is the first middle interdigital transducer, and the A1, A2, A4, and A5 interdigital transducers are the first end interdigital transducers. The structural parameters of the A1 and A5 interdigital transducers are the same, and the structural parameters of the A2 and A4 interdigital transducers are the same, but both are different from the structural parameters of the A3 interdigital transducer. And / or, The second DMS type filter includes five second interdigital transducers, which are designated as B1, B2, B3, B4, and B5 interdigital transducers along the first direction. The B3 interdigital transducer is the second middle interdigital transducer, and the B1, B2, B4, and B5 interdigital transducers are the second end interdigital transducers. The structural parameters of the B1 and B5 interdigital transducers are the same, and the structural parameters of the B2 and B4 interdigital transducers are the same, but both are different from the structural parameters of the B3 interdigital transducer.

5. The filter as described in claim 4, characterized in that, The number of first electrode fingers of the A3 interdigital transducer is less than the number of first electrode fingers of the A2 interdigital transducer, and the number of first electrode fingers of the A2 interdigital transducer is less than or equal to the number of first electrode fingers of the A1 interdigital transducer. And / or, The number of second electrode fingers of the B3 interdigital transducer is greater than the number of second electrode fingers of the B2 interdigital transducer, and the number of second electrode fingers of the B2 interdigital transducer is greater than or equal to the number of second electrode fingers of the B1 interdigital transducer.

6. The filter as described in claim 1, characterized in that, The distance between the midlines of two adjacent first electrode fingers in the first part is less than the distance between the midlines of two adjacent first electrode fingers in the second part; And / or, In the fourth part, the distance between the midlines of two adjacent second electrode fingers is less than the distance between the midlines of two adjacent second electrode fingers in the fifth part.

7. The filter as described in claim 1, characterized in that, The first interdigital transducer, including the first part and the second part, further includes a third part. The first part, the second part and the third part are arranged along the first direction. The number of first electrode fingers in the third part is greater than the number of first electrode fingers in the second part. And / or, The second interdigital transducer, including the fourth and fifth portions, also includes a sixth portion. The fourth, fifth, and sixth portions are arranged along the first direction, and the number of second electrode fingers in the sixth portion is less than the number of second electrode fingers in the fifth portion.

8. The filter as described in claim 7, characterized in that, In the third part, the distance between the midlines of two adjacent first electrode fingers is less than the distance between the midlines of two adjacent first electrode fingers in the second part. And / or, In the sixth part, the distance between the midlines of two adjacent second electrode fingers is less than the distance between the midlines of two adjacent second electrode fingers in the fifth part.

9. The filter as described in claim 7, characterized in that, The first DMS type filter includes an odd number of first interdigital transducers arranged in rows, with only the middle first interdigital transducer including the first part, the second part, and the third part; or, the first DMS type filter includes an even number of first interdigital transducers arranged in rows, with only the two middle first interdigital transducers including the first part, the second part, and the third part. And / or, The second DMS type filter includes an odd number of second interdigital transducers arranged in rows, with only the middle second interdigital transducer including the fourth part, the fifth part, and the sixth part; or, the second DMS type filter includes an even number of second interdigital transducers arranged in rows, with only the two middle second interdigital transducers including the fourth part, the fifth part, and the sixth part.

10. The filter as claimed in claim 1, characterized in that, The first DMS type filter further includes two spaced-apart first reflective gratings, and the at least three first interdigital transducers are located between the two first reflective gratings; And / or, The second DMS type filter also includes two spaced-apart second reflective gratings, with the at least three second interdigital transducers located between the two second reflective gratings.

11. The filter as claimed in claim 1, characterized in that, The number of first electrode fingers of the first middle interdigital transducer of the first DMS type filter ranges from [20, 60], and the number of first electrode fingers of the first end interdigital transducer of the first DMS type filter ranges from [10, 50]. And / or, The number of second electrode fingers of the second middle interdigital transducer of the second DMS type filter ranges from [15, 45], and the number of second electrode fingers of the second end interdigital transducer of the second DMS type filter ranges from [20, 60].

12. The filter as claimed in claim 1, characterized in that, The number of the first electrode fingers in the first part of the first interdigital transducer ranges from [10, 30], and the number of the first electrode fingers in the second part of the first interdigital transducer ranges from [5, 20]. And / or, The number of the second electrode fingers in the fourth part of the second interdigital transducer ranges from [3, 15], and the number of the second electrode fingers in the fifth part of the second interdigital transducer ranges from [10, 30].

13. The filter as claimed in claim 1, characterized in that, The filter further includes an input node and an output node, with the first DMS filter and the second DMS filter connected between the input node and the output node. The filter also satisfies at least one of the following conditions: The filter further includes a first resonator, one port of which is connected to the input node, and the other port of which is grounded; The filter also includes a second resonator, one port of which is connected to the output node and the other port of which is grounded.

14. The filter as claimed in claim 1, characterized in that, The filter is a receiving filter.

15. A filter, characterized in that, It includes a first DMS type filter and a second DMS type filter, wherein the second DMS type filter is connected in parallel with the first DMS type filter; The first DMS type filter includes two first reflective gratings and at least three first interdigital transducers spaced apart along a first direction. The at least three first interdigital transducers are located between the two first reflective gratings. The at least three first interdigital transducers arranged in a row include a first middle interdigital transducer located in the middle and first end interdigital transducers located on both sides of the first middle interdigital transducer. Each of the first interdigital transducers includes a plurality of first electrode fingers, and at least one of the first interdigital transducers includes a first portion, a second portion, and a third portion arranged along the first direction; The second DMS type filter includes two second reflective gratings and at least three second interdigital transducers spaced apart along the first direction. The at least three second interdigital transducers are located between the two second reflective gratings. The at least three second interdigital transducers arranged in a row include a second middle interdigital transducer located in the middle and second end interdigital transducers located on both sides of the second middle interdigital transducer. Each of the second interdigital transducers includes a plurality of second electrode fingers, and at least one of the second interdigital transducers includes a fourth portion, a fifth portion, and a sixth portion arranged along the first direction; Wherein, the number of first electrode fingers of at least one first end interdigital transducer of the first DMS type filter is greater than the number of first electrode fingers of the first middle interdigital transducer, and the number of first electrode fingers in the first part of the first interdigital transducer and / or the number of first electrode fingers in the third part is greater than the number of first electrode fingers in the second part. The number of second electrode fingers in at least one of the second end interdigital transducers of the second DMS type filter is less than the number of second electrode fingers in the second middle interdigital transducer, and the number of second electrode fingers in the fourth part of the second interdigital transducer and / or the number of second electrode fingers in the sixth part is less than the number of second electrode fingers in the fifth part.

16. The filter as claimed in claim 15, characterized in that, The first DMS type filter includes an odd number of first interdigital transducers arranged in rows. The first interdigital transducer located in the middle is the first middle interdigital transducer, and the remaining first interdigital transducers are the first end interdigital transducers. The first middle interdigital transducer includes a first side and a second side. The first interdigital transducers located on the first side and the first interdigital transducers located on the second side are symmetrically arranged with the first middle interdigital transducer as the dividing point; or... The first DMS type filter includes an even number of first interdigital transducers arranged in a row. The two first interdigital transducers located in the middle are the first middle interdigital transducers, and the remaining first interdigital transducers are the first end interdigital transducers. The first DMS type filter has a central axis, which divides the even number of first interdigital transducers into two groups of the same number of first interdigital transducers. The two groups of first interdigital transducers are symmetrically arranged with the central axis as the dividing point.

17. The filter as claimed in claim 15, characterized in that, The first DMS type filter includes five first interdigital transducers. The five first interdigital transducers are A1 interdigital transducer, A2 interdigital transducer, A3 interdigital transducer, A4 interdigital transducer and A5 interdigital transducer along the first direction. The A3 interdigital transducer is the first middle interdigital transducer. The A1 interdigital transducer, A2 interdigital transducer, A4 interdigital transducer and A5 interdigital transducer are the first end interdigital transducers. The structural parameters of the interdigital transducers A1 and A5 are the same, and the structural parameters of the interdigital transducers A2 and A4 are the same, but they are all different from the structural parameters of the interdigital transducer A3.

18. The filter as claimed in claim 15, characterized in that, In the first part, the distance between the midlines of two adjacent first electrode fingers is less than the distance between the midlines of two adjacent first electrode fingers in the second part; and / or, In the third part, the distance between the midlines of two adjacent first electrode fingers is less than the distance between the midlines of two adjacent first electrode fingers in the second part.

19. The filter as claimed in claim 15, characterized in that, The second DMS type filter includes an odd number of second interdigital transducers arranged in rows. The second interdigital transducer located in the middle is the second middle interdigital transducer, and the remaining second interdigital transducers are the second end interdigital transducers. The second middle interdigital transducer includes a third side and a fourth side. The second interdigital transducers located on the third side and the second interdigital transducers located on the fourth side are symmetrically arranged with the second middle interdigital transducer as the dividing point; or... The second DMS type filter includes an even number of second interdigital transducers arranged in a row. The two second interdigital transducers located in the middle are the second middle interdigital transducers, and the remaining second interdigital transducers are the second end interdigital transducers. The second DMS type filter has a central axis, which divides the even number of second interdigital transducers into two groups of the same number of second interdigital transducers. The two groups of second interdigital transducers are symmetrically arranged with the central axis as the dividing point.

20. The filter as claimed in claim 15, characterized in that, The second DMS type filter includes five second interdigital transducers. The five second interdigital transducers are B1 interdigital transducer, B2 interdigital transducer, B3 interdigital transducer, B4 interdigital transducer and B5 interdigital transducer along the first direction. The B3 interdigital transducer is the second middle interdigital transducer. The B1 interdigital transducer, B2 interdigital transducer, B4 interdigital transducer and B5 interdigital transducer are the second end interdigital transducers. The interdigitated transducers B1 and B5 have the same structural parameters, and the interdigitated transducers B2 and B4 have the same structural parameters, but all of them have different structural parameters from the interdigitated transducer B3.

21. The filter as claimed in claim 15, characterized in that, In the fourth part, the distance between the midlines of two adjacent second electrode fingers is less than the distance between the midlines of two adjacent second electrode fingers in the fifth part; and / or, In the sixth part, the distance between the midlines of two adjacent second electrode fingers is less than the distance between the midlines of two adjacent second electrode fingers in the fifth part.

22. A radio frequency module, characterized in that, Includes the filter as described in any one of claims 1 to 21.

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