CN116707486A - Filter, multiplexer and radio frequency front end - Google Patents
Filter, multiplexer and radio frequency front end Download PDFInfo
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- CN116707486A CN116707486A CN202210190315.1A CN202210190315A CN116707486A CN 116707486 A CN116707486 A CN 116707486A CN 202210190315 A CN202210190315 A CN 202210190315A CN 116707486 A CN116707486 A CN 116707486A
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- 230000000694 effects Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 10
- 238000003780 insertion Methods 0.000 description 6
- 230000037431 insertion Effects 0.000 description 6
- 230000001629 suppression Effects 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
- H03H9/6423—Means for obtaining a particular transfer characteristic
- H03H9/6433—Coupled resonator filters
- H03H9/6479—Capacitively coupled SAW resonator filters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
- H03H9/72—Networks using surface acoustic waves
- H03H9/725—Duplexers
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- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The invention belongs to the technical field of filters, and particularly relates to a filter, a multiplexer and a radio frequency front end. The filter includes a plurality of DMS-type filters connected in parallel, the plurality of DMS-type filters including a first DMS-type filter and a second DMS-type filter; the first DMS type filter includes two first reflectors disposed opposite to each other, and a plurality of first IDTs located between the two first reflectors; the second DMS type filter includes two second reflectors disposed 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. In the invention, the filter has better out-of-band rejection effect and larger broadband.
Description
Technical Field
The invention belongs to the technical field of filters, and particularly relates to a filter, a multiplexer and a radio frequency front end.
Background
The acoustic surface filter is a filter commonly used in modern communication systems, and has the advantages of small volume, high stability, strong anti-interference capability, high selectivity and the like. The surface acoustic filters are designed mainly as a ladder structure and a DMS (Double-mode SAW) type filter, wherein the DMS type filter is excellent in low-end suppression and volume, and thus the DMS type filter is widely used in the design of filters and diplexers.
In the prior art, in the hybrid structure filter, two DMS type filters connected in parallel can achieve a larger bandwidth than a single DMS type filter of the same structure. Typically, the parallel DMS-type filter has identical parameters, such as aperture, electrode finger count, electrode finger gap, etc., but this structure does not significantly promote out-of-band rejection for a single DMS-type filter structure.
Disclosure of Invention
The invention solves the technical problem that the out-of-band suppression effect of a DMS type filter in the prior art is not obvious, and provides a filter, a multiplexer and a radio frequency front end.
In view of the above problems, an embodiment of the present invention provides a filter including a plurality of DMS-type filters connected in parallel, the plurality of DMS-type filters including a first DMS-type filter and a second DMS-type filter;
the first DMS type filter includes two first reflectors disposed opposite to each other, and a plurality of first IDTs located between the two first reflectors;
the second DMS type filter includes two second reflectors disposed 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.
Optionally, the structural parameters of the first DMS type filter are different from the structural parameters of the second DMS type filter, including at least one of:
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.
Optionally, the first IDT and the second IDT each include two comb-shaped electrodes disposed in parallel, electrode fingers of the two comb-shaped electrodes are arranged to be mutually intersected, and the first structural parameter includes at least one of a distance between center lines of two adjacent electrode fingers, the number of electrode fingers, and an IDT aperture.
Optionally, the first reflector and the second reflector each comprise a plurality of reflective electrode fingers distributed at intervals, and the second structural parameter comprises a distance between center lines of two adjacent reflective electrode fingers and/or the number of reflective electrode fingers.
Optionally, the first structural parameters of the first IDT and the second IDT are different, including:
the first IDT middle area and the second IDT middle area are different in middle structure parameters, wherein the middle structure parameters comprise the number of electrode fingers of the middle area and/or the distance between the center lines of two adjacent electrode fingers of the middle area.
Optionally, the first structural parameters of the first IDT and the second IDT are different, including:
the edge structure parameters of the edge regions at the two sides of the first IDT are different from those of the edge regions at the two sides of the second IDT, and the edge structure parameters comprise the number of electrode fingers at the edge regions and/or the distance between the center lines of two adjacent electrode fingers at the edge regions.
Optionally, the first structural parameters of the first IDT and the second IDT are different, including:
the distance between the central lines of the two adjacent electrode fingers of the first IDT is larger than the distance between the central lines of the two adjacent electrode fingers of the second IDT;
the first reflector and the second reflector have second different structural parameters, comprising:
the distance between the central lines of two adjacent reflecting electrode fingers of the first reflector is larger than the distance between the central lines of two adjacent reflecting electrode fingers of the second reflector.
Optionally, a plurality of said DMS-type filters have unbalanced outputs.
Optionally, in the first IDT, a distance between center lines of adjacent two electrode fingers in a middle region thereof is greater than a distance between center lines of adjacent two electrode fingers in both side edge regions thereof; and/or
In the second IDT, the distance between the center lines of the adjacent two electrode fingers in the middle area is larger than the distance between the center lines of the adjacent two electrode fingers in the edge areas at the two sides.
The invention also provides a multiplexer comprising the filter.
The invention also provides a radio frequency front end, which comprises the filter.
In the present invention, the first DMS type filter includes two first reflectors and a plurality of first IDTs located between the two first reflectors; the second DMS type 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 type filter are different from the structural parameters of the second DMS type filter. In the plurality of parallel DMS filters, the passband characteristics of at least one of the filters are improved by changing the structural parameters of the filter, and the effect of compensating the passband characteristics of the other DMS filters is achieved, so that a larger bandwidth and a better out-of-band rejection effect are obtained.
Drawings
The invention will be further described with reference to the drawings and examples.
FIG. 1 is a schematic diagram of a filter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a filter provided in the prior art;
FIG. 3 is a schematic diagram of a filter according to the prior art
FIG. 4 is a diagram illustrating a passband insertion loss of a filter according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating an out-of-band rejection of a filter according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating a passband insertion loss of a filter according to an embodiment of the present invention;
FIG. 7 is a diagram illustrating an out-of-band rejection of a filter according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a first IDT or a second IDT according to an embodiment of the present invention.
Reference numerals in the specification are as follows:
1. a signal input terminal; 2. a signal output terminal; 3. a first DMS type filter; 31. a first reflector; 311. a first reflective electrode finger; 32. a first IDT; 321. a first electrode finger; 4. a second DMS type filter; 41. a second reflector; 411. a second reflective electrode finger; 42. a second IDT; 421. a second electrode finger; 5. a first resonator; 6. and a second resonator.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It is to be understood that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "rear", "middle", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.
As shown in fig. 3, the filter provided in the embodiment of the invention includes an input end 1, an output end 2, a first resonator 5 connected in series with the input end, and a second resonator 6 connected in parallel between the first resonator 5 and the input end 1, wherein the second resonator 6 is grounded, the two DMS filters 3 and 4 are connected in parallel, and have a function of single-ended input and single-ended output, and the two DMS filters are connected in series with the first resonator 5 after being connected in parallel. The filter of the present invention is not limited to the filter in fig. 1, but may be a multistage cascade ladder filter in combination with a DMS type filter connected in parallel, or the like.
As shown in fig. 2, in the DMS type filters in general parallel connection, two DMS type filters 3 and 4 having the same structure are connected in parallel; in the present invention, as shown in fig. 1, two DMS filters 3 and 4 having different structures are connected in parallel in the parallel DMS filters.
As shown in fig. 1, an embodiment of the present invention provides a filter including a plurality of DMS (dual mode surface acoustic wave) type filters connected in parallel; the plurality of DMS-type filters includes a first DMS-type filter 3 and a second DMS-type filter 4; it will be appreciated that the number of DMS-type filters may be determined according to practical requirements, and embodiments of the present invention are described with two DMS-type filters in parallel. In a specific embodiment, as shown in fig. 1, the first DMS-type filter 3 and the second DMS-type filter 4 are connected in parallel between the input terminal 1 and the output terminal 2.
The first DMS type filter 3 includes two first reflectors 31 disposed opposite to each other, and a plurality of first IDTs 32 (interdigital transducers) located between the two first reflectors 31; it will be appreciated that the number of the first IDTs 32 may be determined according to actual requirements, and the drawings of the present invention only show examples, for example, the first IDTs 32 may be provided with 3, 5, etc., and a plurality of the first IDTs 32 are spaced apart.
The second DMS type filter 4 includes two second reflectors 41 disposed opposite to each other, and a plurality of second IDTs 42 located between the two second reflectors 41; it will be appreciated that the number of the second IDTs 42 may be determined according to actual requirements, and the drawings of the present invention are only exemplary, for example, the second IDTs 42 are provided with 3, 5, etc., and a plurality of the second IDTs 42 are spaced apart.
The embodiment of the present invention is described in the case where the number of the first IDTs of the first DMS type filter is the same as the number of the second IDTs of the second DMS type filter, and the case where the number of the first IDTs and the number of the second IDTs are different should be understood to be within the scope of the present invention.
Wherein the structural parameters of the first DMS type filter 3 are different from the structural parameters of the second DMS type filter 4. It will be appreciated that the structural parameters of the first DMS-type filter 3 being different from the structural parameters of the second DMS-type filter 4 include: the first IDT32 and the second IDT42 have different structural parameters; and/or the structural parameters of the first reflector 31 and the second reflector 41 are different.
It is understood that the first IDT and the second IDT each include two comb-shaped electrodes disposed in parallel, electrode fingers of the two comb-shaped electrodes are arranged to be interdigitated with each other, and the first structural parameter includes at least one of a distance between center lines of two adjacent electrode fingers, the number of electrode fingers, and an aperture of the IDT. The first reflector and the second reflector each comprise a plurality of reflective electrode fingers which are distributed at intervals, and the second structural parameter comprises the distance between the central lines of two adjacent reflective electrode fingers and/or the number of the reflective electrode fingers.
In the first specific embodiment, the first DMS-type filter 3 is provided with 5 first IDTs 32, and the 5 first IDTs 32 are labeled, in order from left to right, as a first left-order IDT, a second left-order IDT, a third left-order IDT, a fourth left-order IDT, and a fifth left-order IDT; the second DMS type filter 4 is provided with 5 second IDTs 42, and the 5 second IDTs 42 are sequentially labeled from left to right as a first right-order IDT, a second right-order IDT, a third right-order IDT, a fourth right-order IDT, and a fifth right-order IDT; 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 IDT, the fourth left IDT, the second right IDT, and the fourth right IDT are all connected to the signal output terminal 2. And the first structural parameters of the first IDT32 and the second IDT42 are different, including one or more of the following:
1. the first structural parameters of the first left-order IDT and the first right-order IDT are different;
2. the first structural parameters of the second left-order IDT and the second right-order IDT are different;
3. the first structural parameters of the third left-order IDT and the third right-order IDT are different;
4. the first structural parameters of the fourth left-order IDT and the fourth right-order IDT are different;
5. the fifth left-order IDT is different from the first structural parameters of the fifth right-order IDT.
In the second specific embodiment, the first DMS type filter 3 is provided with 3 first IDTs 32, and the second DMS type filter 4 is provided with 3 second IDTs 42; this case is similar to the case where the first DMS type filter 3 is provided with 5 first IDTs 32 and the second DMS type filter 4 is provided with 5 second IDTs 42, and will not be described in detail here.
In the present invention, the first DMS type filter 3 includes two first reflectors 31 and a plurality of first IDTs 32 located between the two first reflectors 31; the second DMS type filter 4 includes two second reflectors 41 and a plurality of second IDTs 42 located between the two second reflectors 41; wherein the first DMS type filter 3 has a structural parameter different from a second structural parameter of the second DMS type filter 4. In the plurality of parallel DMS filters, the passband characteristics of at least one of the filters are improved by changing the structural parameters of the filter, and the effect of compensating the passband characteristics of the other DMS filters is achieved, so that a larger bandwidth and a better out-of-band rejection effect are obtained.
In an embodiment, as shown in fig. 1, each of the first IDT and the second IDT includes two comb-shaped electrodes disposed in parallel, and electrode fingers of the two comb-shaped electrodes are arranged to be interdigitated.
The first structural parameters of the first IDT32 and the second IDT42 being different include one or more of the following;
(1) The distances L1 between the center lines of two adjacent electrode fingers are different (L1 is shown in fig. 8), that is, the first IDT32 includes a plurality of first electrode fingers 321 arranged at intervals, and the second IDT42 includes a plurality of second electrode fingers 421 arranged at intervals; and a first distance between the centerlines of two adjacent first electrode fingers 321 is not equal to a second distance between the centerlines of two adjacent second electrode fingers 421. It will be appreciated that the difference in distance between the centerlines of adjacent two electrode fingers includes: in any of the first IDT and any of the second IDT, the comparison between the distances between any two adjacent electrode fingers may be a comparison between the minimum distance and the minimum distance, or may be a comparison between the average distances.
In a first specific embodiment, as shown in fig. 1, the first distance may be a distance between centerlines of two adjacent first electrode fingers 321 of the first left IDT, and correspondingly, the second distance is a distance between centerlines of two adjacent second electrode fingers 421 of the first right IDT; the first distance may be a distance between centerlines of two adjacent first electrode fingers 321 of the second left IDT, and correspondingly, the second distance is a distance between centerlines of two adjacent second electrode fingers 421 of the second right IDT; the first distance may be a distance between centerlines of two adjacent first electrode fingers 321 of the third left IDT, and correspondingly, the second distance is a distance between centerlines of two adjacent second electrode fingers 421 of the third right IDT; the first distance may be a distance between centerlines of two adjacent first electrode fingers 321 of the fourth left IDT, and correspondingly, the second distance is a distance between centerlines of two adjacent second electrode fingers 421 of the fourth right IDT; the first distance may be a distance between centerlines of two adjacent first electrode fingers 321 of the fifth left IDT, and correspondingly, the second distance is a distance between centerlines of two adjacent second electrode fingers 421 of the fifth right IDT.
(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. In a first specific embodiment, as shown in fig. 1, it includes one or more of the following: the number of the first electrode fingers 321 in the first left IDT is not equal to the number of the second electrode fingers 421 in the first right IDT; the number of the first electrode fingers 321 in the second left IDT is not equal to the number of the second electrode fingers 421 in the second right IDT; the number of the first electrode fingers 321 in the third left IDT is not equal to the number of the second electrode fingers 421 in the third right IDT; the number of the first electrode fingers 321 in the fourth left IDT is not equal to the number of the second electrode fingers 421 in the fourth right IDT; the number of the first electrode fingers 321 in the fifth left IDT is not equal to the number of the second electrode fingers 421 in the fifth right IDT.
(3) The IDT aperture is different, i.e., the first aperture in the first IDT32 is different from the second aperture L2 (L2 is shown in fig. 8) in the second IDT42; the aperture of IDT is the length of the overlapping portion of the electrode fingers of the two comb electrodes. Further, IDT aperture differences include: the first IDT and the second IDT may be a comparison between the minimum aperture and the minimum aperture, or may be a comparison between average apertures.
In a first embodiment, as shown in fig. 1, the first aperture may be a length of an overlapping portion between two adjacent first electrode fingers 321 in the first left IDT, and correspondingly, the second aperture is a length of an overlapping portion between two adjacent second electrode fingers 421 in the first right IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the second left IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the second right IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the third left IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the third right IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the fourth left IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fourth right IDT; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the fifth left IDT, and correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fifth right IDT.
As shown in fig. 1, the first reflector and the second reflector each 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:
(a) The number of the reflecting electrode fingers is different, that is, the first reflector 31 comprises a plurality of first reflecting electrode fingers 311 which are distributed at intervals, and the second reflector 41 comprises a plurality of second reflecting electrode fingers 411 which are distributed at intervals; wherein the number of the first reflective electrode fingers 311 is not equal to the number of the second reflective electrode fingers 411. It will be appreciated that (a) includes at least one of the following two cases: the number of the first reflecting electrode fingers 311 in the first reflector 31 on the left side of the first DMS type filter 3 is different from the number of the second reflecting electrode fingers 411 in the second reflector 41 on the left side of the second DMS type filter 4; the number of the first reflective electrode fingers 311 in the first reflector 31 on the right side of the first DMS type filter 3 is different from the number of the second reflective electrode fingers 411 in the second reflector 41 on the right side of the second DMS type filter 4.
(b) The distance between the centerlines of two adjacent reflective electrode fingers, that is, the third distance between the centerlines of two adjacent first reflective electrode fingers 311, is not equal to the fourth distance between the centerlines of two adjacent second reflective electrode fingers 411. It will be appreciated that the distance between the centre lines of adjacent two reflective electrode fingers includes: in any first reflector 311 and any second reflector 411, the comparison between the distances between any two adjacent reflective electrode fingers may be a comparison between the minimum distance and the minimum distance, or may be a comparison between average distances.
The structural parameters of the first DMS type filter 3 are different from those of the second DMS type filter 3, including: (1) (2) (3) (a) (b) any one or a combination of any plurality of them.
The dashed line in fig. 6 is a passband insertion loss diagram in the prior art (the first DMS type structural parameter and the second DMS type structural parameter are the same), the solid line in fig. 6 is a passband insertion loss diagram in which 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 first structural parameter are all different in the present invention (further, as shown in fig. 1, the solid line in fig. 6 reflects that the second distance is greater than the first distance, the second aperture is greater than the first aperture, and the number of second electrode fingers is greater than the number of first electrode fingers, the fourth distance is greater than the third distance, and the number of second reflective electrode fingers is greater than the number of first reflective electrode fingers); by comparing the solid line with the dashed line in fig. 6, it is clearly possible to bring out that the filter of the invention has a wider passband.
The dashed line in fig. 7 is an out-of-band suppression graph in the prior art (the first DMS type structural parameter and the second DMS type structural parameter are the same), the solid line in fig. 7 is an out-of-band suppression graph in which the distance between the center lines of two adjacent electrode fingers, the number of electrode fingers, and the distance between the center lines of two adjacent electrode fingers in the second structural parameter are different (further, as shown in fig. 1, the solid line in fig. 7 reflects that the second distance is greater than the first distance, the second aperture is greater than the first aperture, and the number of second electrode fingers is greater than the first electrode fingers, the fourth distance is greater than the third distance, and the number of second reflective electrode fingers is greater than the number of first reflective electrode fingers); by comparing the solid line with the broken line in fig. 7, it is clearly possible to bring out that the filter of the present invention has a better out-of-band rejection effect.
In a specific embodiment, the first structural parameters of the first IDT32 and the second IDT42 are different, and further include that the intermediate structural parameters of the first IDT intermediate region and the second IDT intermediate region are different, where 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. The middle region is a region in which the electrode fingers 321 are distributed widely in the first IDT32 or the second IDT 42. For example, when 7 first electrode fingers 321 are included in the first IDT32 as shown in fig. 1, 3 electrode fingers are included in the middle region thereof. It will be appreciated that the number of electrode fingers in the middle area is different, that is, the number of first electrode fingers in the middle area of the first IDT32 is different from the number of second electrode fingers in the middle area of the second IDT42, which is similar to the case of the above (2), and will not be described herein again. The distance between two adjacent electrode fingers in the middle area is different, that is, the distance between the center lines of two adjacent first electrode fingers in the middle area of the first IDT32 is different from the distance between two adjacent second electrode fingers in the middle area of the second IDT42, which is similar to the case of (1), and will not be described herein again.
In the first specific embodiment, the intermediate structure parameter of the intermediate region of the first IDT32 is different from the intermediate structure parameter of the intermediate region of the second IDT42, which includes at least one of the following cases: the middle structural parameters of the first electrode finger 321 in the middle region of the first left IDT are different from the middle structural parameters of the second electrode finger 421 in the middle region of the first right IDT; the middle structural parameters of the first electrode finger 321 in the middle region of the second left IDT are different from the middle structural parameters of the second electrode finger 421 in the middle region of the second right IDT; the middle structural parameters of the first electrode finger 321 in the middle region of the third left IDT are different from the middle structural parameters of the second electrode finger 421 in the middle region of the third right IDT; the middle structural parameters of the first electrode finger 321 in the middle region of the fourth left IDT are different from the middle structural parameters of the second electrode finger 421 in the middle region of the fourth right IDT; the middle structural parameters of the first electrode finger 321 of the middle region of the fifth left IDT are different from the middle structural parameters of the second electrode finger 421 of the middle region of the fifth right IDT.
The first structural parameter differences further include edge structural parameters of the edge regions of the first IDT32 and the edge regions of the second IDT 42. As can be appreciated, the first electrode fingers 321 in the middle area are removed from the first IDT32, and the remaining first electrode fingers 321 are the first electrode fingers 321 in the edge areas on both sides; the edge area is an area with a smaller distribution range of the first electrode fingers 321 in the first IDT 32. As shown in fig. 1, for example, when the first IDT32 includes 7 first electrode fingers 321, two side edge regions thereof include two outer 2 first electrode fingers 321. The structural parameters of the two side edge regions of the second IDT42 are similar to those of the first IDT32, and will not be described again. It will be appreciated that the edge structure parameter differences are similar to the intermediate structure parameter differences and will not be described in detail herein.
In the first embodiment, the first structural parameter of the edge regions on both sides of the first IDT32 is different from the edge structural parameter of the edge regions on both sides of the second IDT42, which includes at least one of the following cases: the edge structure parameters of the first electrode fingers 321 of the edge regions on both sides of the first left IDT are different from the edge structure parameters of the second electrode fingers 421 of the edge regions on both sides of the first right IDT; the edge structure parameters of the first electrode fingers 321 of the edge regions on both sides of the second left IDT are different from the edge structure parameters of the second electrode fingers 421 of the edge regions on both sides of the second right IDT; the edge structure parameters of the first electrode fingers 321 of the edge regions on both sides of the third left IDT are different from the edge structure parameters of the second electrode fingers 421 of the edge regions on both sides of the third right IDT; the edge structure parameters of the first electrode fingers 321 of the edge regions on both sides of the fourth left IDT are different from the edge structure parameters of the second electrode fingers 421 of the edge regions on both sides of the fourth right IDT; the edge structure parameters of the first electrode fingers 321 of the edge regions on both sides of the fifth left IDT are different from the edge structure parameters of the second electrode fingers 421 of the edge regions on both sides of the fifth right IDT.
In a specific embodiment, the distance between the centerlines of two adjacent electrode fingers of the first IDT32 is greater than the distance between the centerlines of two adjacent electrode fingers of the second IDT 42.
The first reflector and the second reflector have second different structural parameters, comprising:
the distance between the central lines of two adjacent reflecting electrode fingers of the first reflector is larger than the distance between the central lines of two adjacent reflecting electrode fingers of the second reflector.
Fig. 4 is a graph of passband insertion loss in the prior art (the first DMS type structural parameter and the second DMS type structural parameter are the same), and fig. 4 is a graph of passband insertion loss when the distance between the center lines of the adjacent two electrode fingers of the first IDT is greater than the distance between the center lines of the adjacent two electrode fingers of the second IDT, and the distance between the center lines of the adjacent two reflecting electrode fingers of the first reflector is greater than the distance between the center lines of the adjacent two reflecting electrode fingers of the second reflector; by comparing the solid line with the dashed line in fig. 4, it is clearly possible to bring out that the filter of the invention has a wider passband.
The dashed line in fig. 5 is an out-of-band suppression graph in the prior art (the first DMS type structural parameter and the second DMS type structural parameter are the same), and the solid line in fig. 5 is an out-of-band suppression graph when the distance between the center lines of the adjacent two electrode fingers of the first IDT is greater than the distance between the center lines of the adjacent two electrode fingers of the second IDT, and the distance between the center lines of the adjacent two reflecting electrode fingers of the first reflector is greater than the distance between the center lines of the adjacent two reflecting electrode fingers of the second reflector in the present invention; by comparing the solid line with the dashed line in fig. 5, it is clearly possible to bring out the filter of the invention with a better out-of-band rejection.
In an embodiment, a plurality of the DMS-type filters have unbalanced outputs, i.e. a plurality of filters have single-ended inputs and single-ended outputs, the output signals being unbalanced signals. Specifically, the first DMS type filter and the second DMS type filter each have unbalanced outputs.
In one embodiment, in the first IDT32, the distance between the center lines of the adjacent two electrode fingers in the middle region is greater than the distance between the center lines of the adjacent two electrode fingers in the edge regions on both sides thereof. That is, in the first IDT32, the distance between the center lines of adjacent two of the first electrode fingers 321 in the middle region is greater than the distance between the center lines of adjacent two of the first electrode fingers 321 in the edge regions on both sides thereof.
In this embodiment, the filter has better out-of-band rejection and greater bandwidth.
In one embodiment, in the second IDT42, the distance between the center lines of the adjacent two electrode fingers in the middle region is greater than the distance between the center lines of the adjacent two electrode fingers in the edge regions on both sides thereof. That is, in the second IDT42, the distance between the center lines of adjacent two of the second electrode fingers 421 in the center region is greater than the distance between the center lines of adjacent two of the second electrode fingers 421 in the both side edge regions thereof.
In this embodiment, the filter has better out-of-band rejection and greater bandwidth.
The invention also provides a multiplexer comprising the filter.
The invention also provides a radio frequency front end, which comprises the filter.
The foregoing description of the preferred embodiment of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A filter comprising a plurality of DMS-type filters connected in parallel, a plurality of said DMS-type filters comprising a first DMS-type filter and a second DMS-type filter;
the first DMS type filter includes two first reflectors disposed opposite to each other, and a plurality of first IDTs located between the two first reflectors;
the second DMS type filter includes two second reflectors disposed 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.
2. The filter of claim 1, wherein the first DMS type filter has a different structural parameter than the second DMS type filter, including at least one of:
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.
3. The filter of claim 2, wherein 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 to be interdigitated with each other, and the first structural parameter includes at least one of a distance between center lines of adjacent two electrode fingers, the number of electrode fingers, and an IDT aperture.
4. The filter of claim 2, wherein the first reflector and the second reflector each comprise a plurality of reflective electrode fingers spaced apart, and the second structural parameter comprises a distance between adjacent two reflective electrode finger centerlines and/or a number of reflective electrode fingers.
5. The filter of claim 2, wherein the first structural parameters of the first IDT and the second IDT are different, comprising:
the middle structure parameters of the first IDT middle region and the second IDT middle region are different, wherein the middle structure parameters comprise the number of electrode fingers of the middle region and/or the distance between the center lines of two adjacent electrode fingers of the middle region; and/or
The edge structure parameters of the edge regions at the two sides of the first IDT are different from those of the edge regions at the two sides of the second IDT, and the edge structure parameters comprise the number of electrode fingers at the edge regions and/or the distance between the center lines of two adjacent electrode fingers at the edge regions.
6. The filter of any of claims 2-5, wherein the first structural parameters of the first IDT and the second IDT are different, comprising:
the distance between the central lines of the two adjacent electrode fingers of the first IDT is larger than the distance between the central lines of the two adjacent electrode fingers of the second IDT;
the first reflector and the second reflector have second different structural parameters, comprising:
the distance between the central lines of two adjacent reflecting electrode fingers of the first reflector is larger than the distance between the central lines of two adjacent reflecting electrode fingers of the second reflector.
7. The filter of claim 1 wherein a plurality of said DMS-type filters have unbalanced outputs.
8. A filter according to claim 2, wherein,
in the first IDT, the distance between the center lines of two adjacent electrode fingers in the middle area is larger than the distance between the center lines of two adjacent electrode fingers in the edge areas at two sides of the first IDT; and/or
In the second IDT, the distance between the center lines of the adjacent two electrode fingers in the middle area is larger than the distance between the center lines of the adjacent two electrode fingers in the edge areas at the two sides.
9. A multiplexer comprising a filter as claimed in any one of claims 1 to 8.
10. A radio frequency front end comprising a filter as claimed in any one of claims 1 to 8.
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