A filter, a multiplexer and a radio frequency front end

Abstract

The present invention belongs to the technical field of filters, and in particular, relates to a filter, a multiplexer and a radio frequency front end. The filter includes a plurality of DMS filters connected in parallel, wherein the plurality of DMS filters include a first DMS filter and a second DMS filter; the first DMS filter includes two first reflectors arranged oppositely and a plurality of first IDTs located between the two first reflectors; the second DMS filter includes two second reflectors arranged oppositely and a plurality of second IDTs located between the two second reflectors; wherein the structural parameters of the first DMS filter are different from those of the second DMS filter. In the present invention, the filter has a better out-of-band suppression effect and a larger broadband.

Description

Technical Field

[0001] The present invention belongs to the technical field of filters, and in particular relates to a filter, a multiplexer and a radio frequency front end. Background Art

[0002] Surface acoustic wave filter is a commonly used filter in modern communication systems. It has the advantages of small size, high stability, strong anti-interference ability and high selectivity. The design of surface acoustic wave filter mainly includes ladder structure and DMS (Double-mode SAW) filter. DMS filter has excellent performance in low-end suppression and volume. Therefore, DMS filter is widely used in the design of filters and duplexers.

[0003] In the prior art, in a hybrid structure filter, two parallel DMS filters can achieve a larger bandwidth than a single DMS filter of the same structure. Usually, the parallel DMS filters have the same structural parameters, such as the aperture, the number of electrode fingers, the electrode finger gap, etc., but this structure does not significantly improve the out-of-band suppression compared to a single DMS filter structure. Summary of the invention

[0004] The invention solves the technical problem in the prior art that the out-of-band suppression effect of the DMS type filter is not obvious, and provides a filter, a multiplexer and a radio frequency front end.

[0005] In view of the above problems, an embodiment of the present invention provides a filter, comprising a plurality of DMS filters connected in parallel, wherein the plurality of DMS filters include a first DMS filter and a second DMS filter;

[0006] The first DMS filter includes two first reflectors arranged opposite to each other and a plurality of first IDTs located between the two first reflectors;

[0007] The second DMS filter includes two second reflectors arranged opposite to each other and a plurality of second IDTs located between the two second reflectors;

[0008] The structural parameters of the first DMS filter are different from the structural parameters of the second DMS filter.

[0009] Optionally, the structural parameters of the first DMS filter are different from the structural parameters of the second DMS filter, including at least one of the following situations:

[0010] The first structural parameters of the first IDT and the second IDT are different;

[0011] The first reflector and the second reflector have different second structural parameters.

[0012] Optionally, the first IDT and the second IDT each include two comb electrodes arranged in parallel, the electrode fingers of the two comb electrodes are arranged crosswise with each other, and the first structural parameter includes at least one of the distance between the center lines of two adjacent electrode fingers, the number of electrode fingers and the IDT aperture.

[0013] Optionally, both the first reflector and the second reflector include a plurality of reflective electrode fingers that are spaced apart, and the second structural parameter includes a distance between center lines of two adjacent reflective electrode fingers and / or the number of reflective electrode fingers.

[0014] Optionally, the first structural parameters of the first IDT and the second IDT are different, including:

[0015] The intermediate structural parameters of the first IDT intermediate region and the second IDT intermediate region are different, wherein the intermediate structural parameters include the number of electrode fingers in the intermediate region and / or the distance between center lines of two adjacent electrode fingers in the intermediate region.

[0016] Optionally, the first structural parameters of the first IDT and the second IDT are different, including:

[0017] The edge structural parameters of the edge regions on both sides of the first IDT and the edge regions on both sides of the second IDT are different, and the edge structural parameters include the number of electrode fingers in the edge region and / or the distance between center lines of two adjacent electrode fingers in the edge region.

[0018] Optionally, the first structural parameters of the first IDT and the second IDT are different, including:

[0019] The distance between the center lines of two adjacent electrode fingers of the first IDT is greater than the distance between the center lines of two adjacent electrode fingers of the second IDT;

[0020] The second structural parameters of the first reflector and the second reflector are different, including:

[0021] A distance between center lines of two adjacent reflective electrode fingers of the first reflector is greater than a distance between center lines of two adjacent reflective electrode fingers of the second reflector.

[0022] Optionally, a plurality of said DMS type filters have unbalanced outputs.

[0023] Optionally, in the first IDT, a distance between center lines of two adjacent electrode fingers in a middle region thereof is greater than a distance between center lines of two adjacent electrode fingers in edge regions on both sides thereof; and / or

[0024] In the second IDT, a distance between center lines of two adjacent electrode fingers in a middle region thereof is greater than a distance between center lines of two adjacent electrode fingers in edge regions on both sides thereof.

[0025] Another embodiment of the present invention further provides a multiplexer including the above-mentioned filter.

[0026] Yet another embodiment of the present invention provides a radio frequency front end, comprising the above-mentioned filter.

[0027] In the present invention, the first DMS filter includes two first reflectors and a plurality of first IDTs located between the two first reflectors; the second DMS filter includes two second reflectors and a plurality of second IDTs located between the two second reflectors; wherein the structural parameters of the first DMS filter are different from the structural parameters of the second DMS filter. Among the multiple parallel DMS filters, the passband characteristics of the filter are improved by changing the structural parameters of at least one of the filters, which plays a role in compensating the passband characteristics of other DMS filters, thereby obtaining a larger bandwidth and a better out-of-band suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Figure 1 A schematic diagram of a filter provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of a filter provided in the prior art;

[0031] Figure 3 A schematic diagram of the structure of a filter provided in the prior art

[0032] Figure 4 A passband insertion loss diagram of a filter provided by an embodiment of the present invention;

[0033] Figure 5 An out-of-band suppression diagram of a filter provided by an embodiment of the present invention;

[0034] Figure 6 A passband insertion loss diagram of a filter provided by an embodiment of the present invention;

[0035] Figure 7 An out-of-band suppression diagram of a filter provided by an embodiment of the present invention;

[0036] Figure 8 A schematic diagram of a first IDT or a second IDT provided according to an embodiment of the present invention.

[0037] The reference numerals in the specification are as follows:

[0038] 1. Signal input terminal; 2. Signal output terminal; 3. First DMS filter; 31. First reflector; 311. First reflective electrode finger; 32. First IDT; 321. First electrode finger; 4. Second DMS filter; 41. Second reflector; 411. Second reflective electrode finger; 42. Second IDT; 421. Second electrode finger; 5. First resonator; 6. Second resonator. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] It should be understood that the directions or positional relationships indicated by terms such as "upper", "lower", "left", "right", "front", "back", and "middle" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation of the present invention.

[0041] like Figure 3 As shown, the filter provided by the embodiment of the present invention includes an input terminal 1, an output terminal 2, a first resonator 5 connected in series with the input terminal, and a second resonator 6 connected in parallel between the first resonator 5 and the input terminal 1, the second resonator 6 is grounded, two DMS filters 3 and 4 are connected in parallel, and have the function of single-ended input and single-ended output, and the two DMS filters are connected in parallel and connected in series with the first resonator 5. The filter of the present invention is not limited to Figure 1 The filter in the embodiment can also be a combination of a multi-stage cascaded ladder filter and a parallel-connected DMS type filter, and so on.

[0042] like Figure 2 As shown, in a general parallel DMS filter, two DMS filters 3 and 4 with the same structure are connected in parallel; in the present invention, as Figure 1 In the parallel DMS filter, two DMS filters 3 and 4 with different structures are connected in parallel.

[0043] like Figure 1As shown, an embodiment of the present invention provides a filter, including a plurality of DMS (dual-mode surface acoustic wave) filters connected in parallel; the plurality of DMS filters include a first DMS filter 3 and a second DMS filter 4; it can be understood that the number of the DMS filters can be determined according to actual needs, and the embodiment of the present invention is described with two parallel DMS filters. In a specific embodiment, as Figure 1 As shown, the first DMS filter 3 and the second DMS filter 4 are connected in parallel between the input end 1 and the output end 2 .

[0044] The first DMS filter 3 includes two first reflectors 31 arranged opposite to each other and a plurality of first IDTs 32 (interdigital transducers) located between the two first reflectors 31; it can be understood that the number of the first IDTs 32 can be determined according to actual needs, and the accompanying drawings of the present invention are only shown as examples. For example, the first IDTs 32 can be provided with 3, 5, etc., and the plurality of first IDTs 32 are arranged at intervals.

[0045] The second DMS filter 4 includes two second reflectors 41 arranged opposite to each other and a plurality of second IDTs 42 located between the two second reflectors 41; it can be understood that the number of the second IDTs 42 can be determined according to actual needs, and the accompanying drawings of the present invention are only shown as examples, for example, the number of the second IDTs 42 is 3, 5, etc., and the plurality of second IDTs 42 are arranged at intervals.

[0046] The embodiment of the present invention is described in the case where the number of first IDTs of the first DMS filter is the same as the number of second IDTs of the second DMS filter. The case where the number of first IDTs and second IDTs is different should also be understood to be within the protection scope of the present invention.

[0047] The structural parameters of the first DMS filter 3 are different from the structural parameters of the second DMS filter 4. It can be understood that the structural parameters of the first DMS filter 3 are different from the structural parameters of the second DMS filter 4, including: the structural parameters of the first IDT 32 and the second IDT 42 are different; and / or the structural parameters of the first reflector 31 and the second reflector 41 are different.

[0048] It can be understood that the first IDT and the second IDT each include two comb-shaped electrodes arranged in parallel, the electrode fingers of the two comb-shaped electrodes are arranged crosswise, and the first structural parameter includes at least one of the distance between the center lines of two adjacent electrode fingers, the number of electrode fingers, and the IDT aperture. The first reflector and the second reflector each include a plurality of reflective electrode fingers distributed at intervals, and the second structural parameter includes the distance between the center lines of two adjacent reflective electrode fingers and / or the number of reflective electrode fingers.

[0049] In the first specific embodiment, the first DMS filter 3 is provided with 5 first IDTs 32, and the 5 first IDTs 32 are marked as the first left-order IDT, the second left-order IDT, the third left-order IDT, the fourth left-order IDT and the fifth left-order IDT from left to right; the second DMS filter 4 is provided with 5 second IDTs 42, and the 5 second IDTs 42 are marked as the first right-order IDT, the second right-order IDT, the third right-order IDT, the fourth right-order IDT and the fifth right-order IDT from left to right; the first left-order IDT, the third left-order IDT, the fifth left-order IDT, the first right-order IDT, the third right-order IDT and the fifth right-order IDT are all connected to the signal input terminal 1; the second left-order IDT, the fourth left-order IDT, the second right-order IDT and the fourth right-order IDT are all connected to the signal output terminal 2. The first structural parameters of the first IDT 32 and the second IDT 42 are different, including one or more of the following situations:

[0050] 1. The first structural parameters of the first left-order IDT and the first right-order IDT are different;

[0051] 2. The first structural parameters of the second left-order IDT and the second right-order IDT are different;

[0052] 3. The first structural parameters of the third left-order IDT and the third right-order IDT are different;

[0053] 4. The first structural parameters of the fourth left-order IDT and the fourth right-order IDT are different;

[0054] 5. The first structural parameters of the fifth left-order IDT and the fifth right-order IDT are different.

[0055] In the second specific embodiment, the first DMS filter 3 is provided with three first IDTs 32, and the second DMS filter 4 is provided with three second IDTs 42; this situation is similar to the situation that the first DMS filter 3 is provided with five first IDTs 32, and the second DMS filter 4 is provided with five second IDTs 42, and will not be repeated here.

[0056] In the present invention, the first DMS filter 3 includes two first reflectors 31 and a plurality of first IDTs 32 located between the two first reflectors 31; the second DMS filter 4 includes two second reflectors 41 and a plurality of second IDTs 42 located between the two second reflectors 41; wherein the structural parameters of the first DMS filter 3 are different from the second structural parameters of the second DMS filter 4. Among the multiple parallel DMS filters, the passband characteristics of the filter are improved by changing the structural parameters of at least one of the filters, which plays a role in compensating the passband characteristics of other DMS filters, thereby obtaining a larger bandwidth and a better out-of-band suppression effect.

[0057] In one embodiment, if Figure 1 As shown, each of the first IDT and the second IDT includes two comb-shaped electrodes arranged in parallel, and the electrode fingers of the two comb-shaped electrodes are arranged crosswise with each other.

[0058] The first structural parameters of the first IDT 32 and the second IDT 42 are different, including one or more of the following situations;

[0059] (1) The distance L1 between the center lines of two adjacent electrode fingers is different (L1 is Figure 8 As shown), that is, the first IDT 32 includes a plurality of first electrode fingers 321 arranged at intervals, and the second IDT 42 includes a plurality of second electrode fingers 421 arranged at intervals; and the first distance between the center lines of two adjacent first electrode fingers 321 is not equal to the second distance between the center lines of two adjacent second electrode fingers 421. It can be understood that the distances between the center lines of two adjacent electrode fingers are different, including: the comparison between the distances between any two adjacent electrode fingers in any first IDT and any second IDT, the comparison between the minimum distance and the minimum distance, and the comparison between the average distances.

[0060] In the first specific embodiment, if Figure 1As shown, the first distance may be the distance between the center lines of the two adjacent first electrode fingers 321 of the first left-order IDT, and correspondingly, the second distance is the distance between the center lines of the two adjacent second electrode fingers 421 of the first right-order IDT; the first distance may be the distance between the center lines of the two adjacent first electrode fingers 321 of the second left-order IDT, and correspondingly, the second distance is the distance between the center lines of the two adjacent second electrode fingers 421 of the second right-order IDT; the first distance may be the distance between the center lines of the two adjacent first electrode fingers 321 of the third left-order IDT, and correspondingly, the second distance is the distance between the center lines of the two adjacent second electrode fingers 421 of the third right-order IDT; the first distance may be the distance between the center lines of the two adjacent first electrode fingers 321 of the fourth left-order IDT, and correspondingly, the second distance is the distance between the center lines of the two adjacent second electrode fingers 421 of the fourth right-order IDT; the first distance may be the distance between the center lines of the two adjacent first electrode fingers 321 of the fifth left-order IDT, and correspondingly, the second distance is the distance between the center lines of the two adjacent second electrode fingers 421 of the fifth right-order IDT.

[0061] (2) The number of electrode fingers is different, that is, the number of first electrode fingers 321 in the first IDT is different from the number of second electrode fingers 421 in the second IDT. Figure 1 As shown, it includes one or more of the following situations: the number of first electrode fingers 321 in the first left-order IDT is not equal to the number of second electrode fingers 421 in the first right-order IDT; the number of first electrode fingers 321 in the second left-order IDT is not equal to the number of second electrode fingers 421 in the second right-order IDT; the number of first electrode fingers 321 in the third left-order IDT is not equal to the number of second electrode fingers 421 in the third right-order IDT; the number of first electrode fingers 321 in the fourth left-order IDT is not equal to the number of second electrode fingers 421 in the fourth right-order IDT; the number of first electrode fingers 321 in the fifth left-order IDT is not equal to the number of second electrode fingers 421 in the fifth right-order IDT.

[0062] (3) The IDT apertures are different, that is, the first aperture in the first IDT 32 and the second aperture L2 in the second IDT 42 (L2 is as shown in FIG. Figure 8 It should be noted that the aperture of the IDT is the length of the overlapping portion of the electrode fingers of the two comb-shaped electrodes. Further, the different apertures of the IDT include: in any first IDT and any second IDT, it can be a comparison between the minimum aperture and the minimum aperture, or it can be a comparison between the average apertures.

[0063] In the first specific embodiment, if Figure 1 As shown, the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the first left-order IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the first right-order IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the second left-order IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the second right-order IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the third left-order IDT, Correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the third right-order IDT; the first aperture can be the length of the overlapping portion between two adjacent first electrode fingers 321 in the fourth left-order IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fourth right-order IDT; the first aperture can be the length of the overlapping portion between two adjacent first electrode fingers 321 in the fifth left-order IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fifth right-order IDT.

[0064] like Figure 1 As shown, the first reflector and the second reflector both include a plurality of reflective electrode fingers that are spaced apart, and the second structural parameters of the first reflector 31 and the second reflector 41 are different, including one or more of the following situations:

[0065] (a) The number of reflection electrode fingers is different, that is, the first reflector 31 includes a plurality of first reflection electrode fingers 311 distributed at intervals, and the second reflector 41 includes a plurality of second reflection electrode fingers 411 distributed at intervals; wherein the number of the first reflection electrode fingers 311 is not equal to the number of the second reflection electrode fingers 411. It can be understood that (a) includes at least one of the following two situations: the number of the first reflection electrode fingers 311 in the first reflector 31 on the left side of the first DMS filter 3 is not equal to the number of the second reflection electrode fingers 411 in the second reflector 41 on the left side of the second DMS filter 4; the number of the first reflection electrode fingers 311 in the first reflector 31 on the right side of the first DMS filter 3 is not equal to the number of the second reflection electrode fingers 411 in the second reflector 41 on the right side of the second DMS filter 4.

[0066] (b) The distance between the center lines of two adjacent reflection electrode fingers, that is, the third distance between the center lines of two adjacent first reflection electrode fingers 311, is not equal to the fourth distance between the center lines of two adjacent second reflection electrode fingers 411. It can be understood that the distance between the center lines of two adjacent reflection electrode fingers includes: the comparison between the distances of any two adjacent reflection electrode fingers in any first reflector 311 and any second reflector 411, and can also be the comparison between the minimum distance and the minimum distance, or the comparison between the average distances.

[0067] It should be noted that the structural parameters of the first DMS filter 3 and the structural parameters of the second DMS filter 3 are different from each other and include any one or any combination of (1), (2), (3), (a), (b).

[0068] Figure 6 The middle dashed line is the passband insertion loss diagram in the prior art (the first DMS type structure parameters and the second DMS type structure parameters are the same), Figure 6 The solid line in the middle is a passband insertion loss diagram in the present invention, in which the distance between the center lines of two adjacent electrode fingers, the number of electrode fingers in the first structural parameter, and the number of reflection electrode fingers and the distance between the center lines of two adjacent reflection electrode fingers in the second structural parameter are all different (furthermore, as Figure 1 As shown, Figure 6 The solid line reflects that the second distance is greater than the first distance, the second aperture is greater than the first aperture, the number of the second electrode fingers is greater than the number of the first electrode fingers, the fourth distance is greater than the third distance, and the number of the second reflective electrode fingers is greater than the number of the first reflective electrode fingers); Figure 6 Comparison between the solid line and the dotted line clearly shows that the filter of the present invention has a wider passband.

[0069] Figure 7 The middle dashed line is the out-of-band suppression diagram in the prior art (the first DMS type structure parameters and the second DMS type structure parameters are the same), Figure 7 The solid line in the middle is the out-of-band suppression diagram of the distance between the center lines of two adjacent electrode fingers, the number of electrode fingers, and the number of reflective electrode fingers and the distance between the center lines of two adjacent reflective electrode fingers in the second structural parameter in the present invention (furthermore, as Figure 1 As shown, Figure 7 The solid line reflects that the second distance is greater than the first distance, the second aperture is greater than the first aperture, the number of the second electrode fingers is greater than the number of the first electrode fingers, the fourth distance is greater than the third distance, and the number of the second reflective electrode fingers is greater than the number of the first reflective electrode fingers); Figure 7 Comparison between the solid line and the dotted line clearly shows that the filter of the present invention has a better out-of-band suppression effect.

[0070] In a specific embodiment, the first structural parameters of the first IDT32 and the second IDT42 are different, and the intermediate structural parameters of the first IDT intermediate region and the second IDT intermediate region are different, wherein the intermediate structural parameters include the number of electrode fingers in the intermediate region and / or the distance between the center lines of two adjacent electrode fingers in the intermediate region. It should be noted that the intermediate region is a region where the electrode fingers 321 in the first IDT32 or the second IDT42 are distributed in a larger range. For example, Figure 1 When the first IDT32 includes 7 first electrode fingers 321, the middle region includes 3 electrode fingers. It can be understood that the number of electrode fingers in the middle region is different, that is, the number of first electrode fingers in the middle region of the first IDT32 is different from the number of second electrode fingers in the middle region of the second IDT42. This situation is similar to (2) above and will not be repeated here; the distance between two adjacent electrode fingers in the middle region is different, that is, the distance between the center lines of two adjacent first electrode fingers in the middle region of the first IDT32 is different from the distance between two adjacent second electrode fingers in the middle region of the second IDT42. This situation is similar to (1) and will not be repeated here.

[0071] In a first specific embodiment, the intermediate structural parameters of the intermediate region of the first IDT32 are different from the intermediate structural parameters of the intermediate region of the second IDT42, including at least one of the following situations: the intermediate structural parameters of the first electrode finger 321 of the intermediate region of the first left-order IDT are different from the intermediate structural parameters of the second electrode finger 421 of the intermediate region of the first right-order IDT; the intermediate structural parameters of the first electrode finger 321 of the intermediate region of the second left-order IDT are different from the intermediate structural parameters of the second electrode finger 421 of the intermediate region of the second right-order IDT; the intermediate structural parameters of the first electrode finger 321 of the intermediate region of the third left-order IDT are different from the intermediate structural parameters of the second electrode finger 421 of the intermediate region of the third right-order IDT; the intermediate structural parameters of the first electrode finger 321 of the intermediate region of the fourth left-order IDT are different from the intermediate structural parameters of the second electrode finger 421 of the intermediate region of the fourth right-order IDT; the intermediate structural parameters of the first electrode finger 321 of the intermediate region of the fifth left-order IDT are different from the intermediate structural parameters of the second electrode finger 421 of the intermediate region of the fifth right-order IDT.

[0072] The first structural parameter difference also includes that the edge structural parameters of the edge regions on both sides of the first IDT32 and the edge regions on both sides of the second IDT42 are different. It can be understood that, except for the first electrode fingers 321 in the middle region of the first IDT32, the remaining are the first electrode fingers 321 in the edge regions on both sides; the edge regions are the regions where the first electrode fingers 321 in the first IDT32 have a smaller distribution range. Figure 1As shown, for example, when the first IDT 32 includes 7 first electrode fingers 321, the edge regions on both sides thereof include two first electrode fingers 321 on both outer sides. The structural parameters of the edge regions on both sides of the second IDT 42 are similar to those of the first IDT 32, and will not be described in detail here. It can be understood that the difference in edge structural parameters is similar to the difference in middle structural parameters, and will not be described in detail here.

[0073] In a first specific embodiment, the first structural parameters of the edge regions on both sides of the first IDT32 are different from the edge structural parameters of the edge regions on both sides of the second IDT42, including at least one of the following situations: the edge structural parameters of the first electrode fingers 321 on both sides of the first left-order IDT are different from the edge structural parameters of the second electrode fingers 421 on both sides of the first right-order IDT; the edge structural parameters of the first electrode fingers 321 on both sides of the second left-order IDT are different from the edge structural parameters of the second electrode fingers 421 on both sides of the second right-order IDT; the edge structural parameters of the first electrode fingers 321 on both sides of the third left-order IDT are different from the edge structural parameters of the second electrode fingers 421 on both sides of the third right-order IDT; the edge structural parameters of the first electrode fingers 321 on both sides of the fourth left-order IDT are different from the edge structural parameters of the second electrode fingers 421 on both sides of the fourth right-order IDT; the edge structural parameters of the first electrode fingers 321 on both sides of the fifth left-order IDT are different from the edge structural parameters of the second electrode fingers 421 on both sides of the fifth right-order IDT.

[0074] In a specific embodiment, a distance between center lines of two adjacent electrode fingers of the first IDT 32 is greater than a distance between center lines of two adjacent electrode fingers of the second IDT 42 .

[0075] The second structural parameters of the first reflector and the second reflector are different, including:

[0076] A distance between center lines of two adjacent reflective electrode fingers of the first reflector is greater than a distance between center lines of two adjacent reflective electrode fingers of the second reflector.

[0077] Figure 4 The middle dashed line is the passband insertion loss diagram in the prior art (the first DMS type structure parameters and the second DMS type structure parameters are the same), Figure 4 The solid line in the middle is a passband insertion loss diagram when the distance between the center lines of two adjacent electrode fingers of the first IDT is greater than the distance between the center lines of two adjacent electrode fingers of the second IDT, and the distance between the center lines of two adjacent reflection electrode fingers of the first reflector is greater than the distance between the center lines of two adjacent reflection electrode fingers of the second reflector; Figure 4 Comparison between the solid line and the dotted line clearly shows that the filter of the present invention has a wider passband.

[0078] Figure 5 The middle dashed line is the out-of-band suppression diagram in the prior art (the first DMS type structure parameters and the second DMS type structure parameters are the same), Figure 5 The solid line in the middle is an out-of-band suppression diagram when the distance between the center lines of two adjacent electrode fingers of the first IDT is greater than the distance between the center lines of two adjacent electrode fingers of the second IDT, and the distance between the center lines of two adjacent reflection electrode fingers of the first reflector is greater than the distance between the center lines of two adjacent reflection electrode fingers of the second reflector in the present invention; Figure 5 Comparison between the solid line and the dotted line clearly shows that the filter of the present invention has a better out-of-band suppression effect.

[0079] In one embodiment, the plurality of DMS filters have unbalanced outputs, that is, the plurality of filters have single-ended inputs and single-ended outputs, and the output signals are unbalanced signals. Specifically, the first DMS filter and the second DMS filter both have unbalanced outputs.

[0080] In one embodiment, in the first IDT 32, the distance between the center lines of two adjacent electrode fingers in the middle region is greater than the distance between the center lines of two adjacent electrode fingers in the edge regions on both sides. That is, in the first IDT 32, the distance between the center lines of two adjacent first electrode fingers 321 in the middle region is greater than the distance between the center lines of two adjacent first electrode fingers 321 in the edge regions on both sides.

[0081] In this embodiment, the filter has better out-of-band suppression effect and larger bandwidth.

[0082] In one embodiment, in the second IDT 42, the distance between the center lines of two adjacent electrode fingers in the middle region is greater than the distance between the center lines of two adjacent electrode fingers in the edge regions on both sides thereof. That is, in the second IDT 42, the distance between the center lines of two adjacent second electrode fingers 421 in the center region is greater than the distance between the center lines of two adjacent second electrode fingers 421 in the edge regions on both sides thereof.

[0083] In this embodiment, the filter has better out-of-band suppression effect and larger bandwidth.

[0084] Another embodiment of the present invention further provides a multiplexer including the above-mentioned filter.

[0085] Yet another embodiment of the present invention provides a radio frequency front end, comprising the above-mentioned filter.

[0086] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A filter, characterized in that: comprising a plurality of DMS filters connected in parallel, the plurality of DMS filters comprising a first DMS filter and a second DMS filter; The first DMS filter includes two first reflectors arranged opposite to each other and a plurality of first IDTs located between the two first reflectors; The second DMS filter includes two second reflectors arranged opposite to each other and a plurality of second IDTs located between the two second reflectors; wherein the structural parameters of the first DMS type filter are different from the structural parameters of the second DMS type filter; The structural parameters of the first DMS filter are different from the structural parameters of the second DMS filter, including: the first structural parameters of the first IDT and the second IDT are different; the second structural parameters of the first reflector and the second reflector are different; The first structural parameter includes the distance between the center lines of two adjacent electrode fingers of the IDT; the second structural parameter includes the distance between the center lines of two adjacent reflection electrode fingers of the reflector; The distance between the center lines of two adjacent electrode fingers of the first IDT is greater than the distance between the center lines of two adjacent electrode fingers of the second IDT; the distance between the center lines of two adjacent reflection electrode fingers of the first reflector is greater than the distance between the center lines of two adjacent reflection electrode fingers of the second reflector.

2. The filter according to claim 1, characterized in that The first IDT and the second IDT each include two comb-shaped electrodes arranged in parallel, electrode fingers of the two comb-shaped electrodes are arranged crosswise with each other, and the first structural parameter also includes at least one of the number of electrode fingers and IDT aperture.

3. The filter according to claim 1, characterized in that The first reflector and the second reflector both include a plurality of reflective electrode fingers that are spaced apart from each other, and the second structural parameter also includes the number of the reflective electrode fingers.

4. The filter according to claim 1, characterized in that The first structural parameters of the first IDT and the second IDT are different, and further include: The intermediate structural parameters of the first IDT intermediate region and the second IDT intermediate region are different, wherein the intermediate structural parameters include the number of electrode fingers in the intermediate region and / or the distance between center lines of two adjacent electrode fingers in the intermediate region; and / or The edge structural parameters of the edge regions on both sides of the first IDT and the edge regions on both sides of the second IDT are different, and the edge structural parameters include the number of electrode fingers in the edge region and / or the distance between center lines of two adjacent electrode fingers in the edge region.

5. The filter according to claim 1, characterized in that A plurality of said DMS type filters have unbalanced outputs.

6. The filter according to claim 1, characterized in that In the first IDT, the distance between the center lines of two adjacent electrode fingers in the middle region is greater than the distance between the center lines of two adjacent electrode fingers in the edge regions on both sides thereof; and / or In the second IDT, a distance between center lines of two adjacent electrode fingers in a middle region thereof is greater than a distance between center lines of two adjacent electrode fingers in edge regions on both sides thereof.

7. A multiplexer, characterized in that: Comprising a filter as described in any one of claims 1-6.

8. A radio frequency front end, characterized in that: Comprising a filter as described in any one of claims 1-6.

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