CN116707486A - Filter, multiplexer and radio frequency front end - Google Patents

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

A filter, multiplexer and radio frequency front end

technical field

The invention belongs to the technical field of filters, in particular to a filter, a multiplexer and a radio frequency front end.

Background technique

Surface acoustic filter is a kind of filter commonly used 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 filters mainly includes ladder structure and DMS (Double-mode SAW, dual-mode surface acoustic wave) type filters, among which DMS type filters are excellent in low-end suppression and volume, so DMS type filters are widely used in in the design of filters and duplexers.

In the prior art, in a filter with a hybrid structure, two parallel DMS filters can achieve a larger bandwidth than a single DMS filter with the same structure. Usually, the structural parameters of parallel DMS filters are the same, such as the aperture, the number of electrode fingers, and the gap between electrode fingers, etc. Not obvious.

Contents of the invention

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

In view of the above problems, a filter provided by an embodiment of the present invention includes a plurality of DMS-type filters connected in parallel, and the plurality of DMS-type filters include a first DMS-type filter and a second DMS-type filter;

The first DMS type filter includes two first reflectors arranged oppositely and a plurality of first IDTs located between the two first reflectors;

The second DMS type 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 the structural parameters of the second DMS 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 following situations:

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, both the first IDT and the second IDT include two comb-shaped electrodes arranged in parallel, the electrode fingers of the two comb-shaped electrodes are arranged to cross each other, and the first structural parameters include adjacent At least one of the distance between the centerlines of two electrode fingers, the number of electrode fingers, and the aperture of the IDT.

Optionally, both the first reflector and the second reflector include a plurality of reflective electrode fingers distributed at intervals, and the second structural parameters include the distance between the centerlines of two adjacent reflective electrode fingers and/or or the number of reflective electrode fingers.

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

The middle structure parameters of the first IDT middle region and the second IDT middle region are different, and the middle structure parameters include the number of electrode fingers in the middle region and/or the distance between the centerlines of two adjacent electrode fingers in the middle region.

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

The edge structure parameters of the edge areas on both sides of the first IDT are different from those of the edge areas on both sides of the second IDT, and the edge structure parameters include the number of electrode fingers in the edge area and/or the distance between the centerlines of two adjacent electrode fingers in the edge area. distance between.

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

The distance between the centerlines of two adjacent electrode fingers of the first IDT is greater than the distance between the centerlines of two adjacent electrode fingers of the second IDT;

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

The distance between the centerlines of two adjacent reflective electrode fingers of the first reflector is greater than the distance between the centerlines of two adjacent reflective electrode fingers of the second reflector.

Optionally, a plurality of said DMS-type filters have unbalanced outputs.

Optionally, in the first IDT, the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides; and/ or

In the second IDT, the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides.

Another embodiment of the present invention also provides a multiplexer, including the above-mentioned filter.

Yet another embodiment of the present invention also provides a radio frequency front end, including the above-mentioned filter.

In the present invention, the first DMS filter includes two first reflectors and a plurality of first IDTs between the two first reflectors; the second DMS filter includes two second reflectors and A plurality of second IDTs located between two of the second reflectors; wherein the structural parameters of the first DMS-type filter are different from the structural parameters of the second DMS-type filter. Among multiple DMS filters connected in parallel, 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 Better out-of-band rejection.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic diagram of a filter provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a filter provided in the prior art;

Fig. 3 is the structural representation of the filter provided in the prior art

FIG. 4 is a passband insertion loss diagram of a filter provided by an embodiment of the present invention;

FIG. 5 is an out-of-band suppression diagram of a filter provided by an embodiment of the present invention;

FIG. 6 is a passband insertion loss diagram of a filter provided by an embodiment of the present invention;

FIG. 7 is an out-of-band suppression diagram of a filter provided by an embodiment of the present invention;

Fig. 8 is a schematic diagram of a first IDT or a second IDT provided by an embodiment of the present invention.

The reference signs in the instructions are as follows:

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 , the second DMS type filter; 41, the second reflector; 411, the second reflective electrode finger; 42, the second IDT; 421, the second electrode finger; 5, the first resonator; 6, the second resonator.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

It should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "middle", etc. are based on the orientation or position shown in the drawings The relationship is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

As shown in Figure 3, in the filter that the embodiment of the present invention provides, comprise input terminal 1, output terminal 2, the first resonator 5 that is connected in series with input terminal, and between the first resonator 5 and input terminal 1 The second resonator 6 is connected in parallel, the second resonator 6 is grounded, and the two DMS filters 3 and 4 are connected in parallel, which has the function of single-ended input and single-ended output, and the two DMS filters are connected in parallel with the first resonator 5 connected in series. The filter of the present invention is not limited to the filter shown in FIG. 1 , and it can also be a multi-stage cascaded ladder filter combined with a DMS filter connected in parallel, and so on.

As shown in Figure 2, in the DMS type filter of general parallel connection, by two DMS type filters 3 and 4 parallel connections of identical structure; In the present invention, as described in Figure 1, in the DMS type filter of parallel connection, Two DMS type filters 3 and 4 with different structures are connected in parallel.

As shown in Figure 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; a plurality of DMS type filters include a first DMS type filter 3 and the second DMS filter 4; understandably, the number of the DMS filters can be determined according to actual needs, and the embodiment of the present invention is described as two parallel DMS filters. In a specific embodiment, as shown in FIG. 1 , the first DMS filter 3 and the second DMS 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 oppositely arranged and a plurality of first IDT32 (interdigital transducers) between the two first reflectors 31; understandably , the number of the first IDT32 can be determined according to actual needs, and the drawings of the present invention are only shown as examples, for example, the first IDT32 can be provided with 3, 5, etc. set up.

The second DMS type filter 4 includes two second reflectors 41 oppositely arranged and a plurality of second IDT42 between the two second reflectors 41; it can be understood that the second IDT42 The number can be determined according to actual needs, and the drawings of the present invention are only shown as examples, for example, there are 3, 5, etc. of the second IDT42, and a plurality of the second IDT42 are arranged at intervals.

The embodiment of the present invention is described in the case where the first IDT number of the first DMS filter is the same as the second IDT number of the second DMS filter, and the case where the first IDT and the second IDT number are different should also be understood as Within the protection scope of the present invention.

Wherein, the structural parameters of the first DMS filter 3 are different from those of the second DMS filter 4 . It can be understood that the difference between the structural parameters of the first DMS filter 3 and the structural parameters of the second DMS filter 4 includes: the structural parameters of the first IDT32 and the second IDT42 are different; and/ Or the structural parameters of the first reflector 31 and the second reflector 41 are different.

It can be understood that both the first IDT and the second IDT include two comb electrodes arranged in parallel, and the electrode fingers of the two comb electrodes are arranged to cross each other, and the first structural parameters include phase At least one of the distance between the centerlines of two adjacent electrode fingers, the number of electrode fingers, and the aperture of the IDT. Both the first reflector and the second reflector include a plurality of reflective electrode fingers distributed at intervals, and the second structural parameters include the distance between the centerlines of two adjacent reflective electrode fingers and/or the reflective electrode fingers quantity.

In the first specific embodiment, the first DMS filter 3 is provided with five first IDT32, and the five first IDT32 are marked as the first left-order IDT and the second left-order IDT from left to right. , the third left-order IDT, the fourth left-order IDT and the fifth left-order IDT; the second DMS filter 4 is provided with five second IDT42, and the five second IDT42 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; the first left-order IDT, the third left-order IDT, the fifth The left-stage IDT, the first right-stage IDT, the third right-stage IDT, and the fifth right-stage IDT are all connected to the signal input terminal 1; the second left-stage IDT, the fourth left-stage The IDT, the second right-stage IDT, and the fourth right-stage IDT are all connected to the signal output terminal 2 . The difference in the first structural parameters of the first IDT32 and the second IDT42 includes one or more of the following situations:

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 parameter of the fourth left-order IDT is different from that of the fourth right-order IDT;

5. The first structural parameter of the fifth left-order IDT is different from that of the fifth right-order IDT.

In the second specific embodiment, the first DMS filter 3 is provided with three first IDT32, and the second DMS filter 4 is provided with three second IDT42; The DMS-type filter 3 is provided with five first IDT32, and the second DMS-type filter 4 is provided with five second IDT42.

In the present invention, the first DMS filter 3 includes two first reflectors 31 and a plurality of first IDT32 between the two first reflectors 31; the second DMS filter 4 includes two first reflectors 31; Two reflectors 41 and a plurality of second IDT42 between the two second reflectors 41; wherein, the structural parameters of the first DMS filter 3 are the same as the first DMS filter 4 The two structural parameters are different. Among multiple DMS filters connected in parallel, 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 Better out-of-band rejection.

In one embodiment, as shown in FIG. 1 , both the first IDT and the second IDT include two comb-shaped electrodes arranged in parallel, and electrode fingers of the two comb-shaped electrodes are arranged to cross each other.

The difference between the first structural parameters of the first IDT32 and the second IDT42 includes one or more of the following situations;

(1) The distance L1 between the centerlines of two adjacent electrode fingers is 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 It includes a plurality of second electrode fingers 421 arranged at intervals; and the first distance between the centerlines of two adjacent first electrode fingers 321 is not equal to the centerlines of two adjacent second electrode fingers 421 The second distance between. It can be understood that the different distances between the centerlines of adjacent two adjacent electrode fingers include: in any first IDT and any second IDT, the comparison between the distances between any two adjacent electrode fingers can also be the minimum distance The comparison with the minimum distance may also be a comparison with the average distance.

In the first specific embodiment, as shown in FIG. 1, the first distance may be the distance between the centerlines of two adjacent first electrode fingers 321 of the first left-stage IDT. Correspondingly, The second distance is the distance between the center lines of two adjacent second electrode fingers 421 of the first right-order IDT; the first distance may be the distance between two adjacent second electrode fingers 421 of the second left-order IDT. The distance between the centerlines of the first electrode fingers 321, correspondingly, the second distance is the distance between the centerlines of two adjacent second electrode fingers 421 of the second right-level IDT; The first distance may be the distance between the centerlines of two adjacent first electrode fingers 321 of the third left-stage IDT, and correspondingly, the second distance is the distance between the centerlines of the third right-stage IDT. The distance between the centerlines of two adjacent second electrode fingers 421; the first distance may be the distance between the centerlines of two adjacent first electrode fingers 321 of the fourth left-level IDT , correspondingly, the second distance is the distance between the centerlines of two adjacent second electrode fingers 421 of the fourth right-order IDT; the first distance may be the fifth left-order IDT The distance between the centerlines of two adjacent first electrode fingers 321, correspondingly, the second distance is the distance between the centerlines of two adjacent second electrode fingers 421 of the fifth right-order IDT distance between.

(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 the first specific embodiment, as shown in FIG. 1 , it includes one or more of the following situations: the number of first electrode fingers 321 in the first left-stage IDT is not equal to the number of first electrode fingers 321 in the first right-stage IDT The number of the second electrode fingers 421; the number of the first electrode fingers 321 in the second left-level IDT is not equal to the number of the second electrode fingers 421 in the second right-level IDT; the third left The number of first electrode fingers 321 in the third-level IDT is not equal to the number of the second electrode fingers 421 in the third right-level IDT; the number of first electrode fingers 321 in the fourth left-level IDT is not equal to the number of the first electrode fingers 421 The number of the second electrode fingers 421 in the fourth right-level IDT; the number of the first electrode fingers 321 in the fifth left-level IDT is not equal to the number of the second electrode fingers 421 in the fifth right-level IDT.

(3) IDT apertures are different, that is, the first aperture in the first IDT32 is different from the second aperture L2 (L2 shown in Figure 8) in the second IDT42; The electrode refers to the length of the overlapping portion of the shape electrode. Further, the difference in IDT pore size includes: in any first IDT and any second IDT, it may be a comparison between the minimum pore size and the minimum pore size, and may also be a comparison between average pore sizes.

In the first specific embodiment, as shown in FIG. 1, the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the first left-stage IDT. Correspondingly, the The second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the first right-stage IDT; the first aperture may be the length of the overlapping portion between two adjacent second electrode fingers 421 in the second left-stage IDT. The length of the overlapping portion between one electrode finger 321, correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the second right-stage IDT; the first The aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the third left-stage IDT, and correspondingly, the second aperture is the length of the adjacent two first electrode fingers 321 in the third right-stage IDT. The length of the overlapping portion between the second electrode fingers 421; the first aperture may be the length of the overlapping portion between two adjacent first electrode fingers 321 in the fourth left-order IDT, and correspondingly, the second The aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fourth right-stage IDT; the first aperture may be the length of the adjacent two first electrodes in the fifth left-stage IDT The length of the overlapping portion between the fingers 321, correspondingly, the second aperture is the length of the overlapping portion between two adjacent second electrode fingers 421 in the fifth right-level IDT.

As shown in FIG. 1, both the first reflector and the second reflector include a plurality of reflective electrode fingers distributed at intervals, and the second structural parameters of the first reflector 31 and the second reflector 41 different, including one or more of the following:

(a) The number of reflective electrode fingers is different, that is, the first reflector 31 includes a plurality of first reflective electrode fingers 311 distributed at intervals, and the second reflector 41 includes a plurality of second reflective electrode fingers distributed at intervals 411 ; wherein, the number of the first reflective electrode fingers 311 is not equal to the number of the second reflective electrode fingers 411 . It can be understood that (a) includes at least one of the following two conditions: the number of first reflective electrode fingers 311 in the first reflector 31 on the left side of the first DMS filter 3, and the number of The number of second reflective electrode fingers 411 in the second reflector 41 on the left side of the second DMS filter 4 is not equal; the first reflector 31 on the right side of the first DMS filter 3 The number of reflective electrode fingers 311 is different from the number of second reflective electrode fingers 411 in the second reflector 41 on the right side of the second DMS 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 distance between two adjacent first reflective electrode fingers 311 The fourth distance between the centerlines of the two reflective electrode fingers 411 . It can be understood that the distance between the centerlines of two adjacent reflective electrode fingers includes: a comparison between the distances between any two adjacent reflective electrode fingers in any first reflector 311 and any second reflector 411, or It is a comparison between the minimum distance and the minimum distance, and it can also be a comparison between the average distance.

It should be noted that the structural parameters of the first DMS filter 3 are different from the structural parameters of the second DMS filter 3, including: (1) (2) (3) (a) (b) any one or any number of combinations.

Dotted line in Fig. 6 is the passband insertion loss figure in the prior art (the first DMS type structure parameter is the same as the second DMS type structure parameter), and solid line among Fig. 6 is in the present invention, in the first structure parameter adjacent two The distance between the centerlines of each electrode finger, the number of electrode fingers, and the number of reflective electrode fingers in the second structural parameter and the passband insertion loss diagram (further) that are different from the distance between the centerlines of two adjacent reflective electrode fingers Ground, as shown in Figure 1, the solid line in Figure 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 the second electrode fingers is greater than the number of the first electrode fingers, the fourth distance 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 and the dotted line in Figure 6, it can be clearly brought out that the filter of the present invention has a wider passband.

Dotted line in Fig. 7 is the out-of-band suppression figure in the prior art (the first DMS type structure parameter is identical with the second DMS type structure parameter), and solid line among Fig. 7 is between adjacent two electrode finger centerlines in the present invention The distance between the distance, the number of electrode fingers, and the number of reflective electrode fingers in the second structural parameter and the different out-of-band suppression diagrams of the distance between the centerlines of two adjacent reflective electrode fingers (further, as shown in Figure 1, Fig. The solid line in 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 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 second reflection The number of electrode fingers is greater than the number of first reflective electrode fingers); by comparing the solid line and the dotted line in Figure 7, it can be clearly brought out that the filter of the present invention has a better out-of-band suppression effect.

In a specific embodiment, the first structure parameters of the first IDT32 and the second IDT42 are different, and the intermediate structure parameters of the first IDT middle area and the second IDT middle area are different, and the middle The structural parameters include the number of electrode fingers in the middle region and/or the distance between the centerlines of two adjacent electrode fingers in the middle region. It should be noted that the middle area is the area where the electrode fingers 321 are distributed in a relatively large range in the first IDT32 or the second IDT42. For example, when the first IDT 32 includes 7 first electrode fingers 321 as shown in FIG. 1 , its middle area includes 3 electrode fingers. It can be understood 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. This situation is different from the above (2) is similar, and will not be repeated here; the distance between the adjacent two electrode fingers in the middle area is different, that is, the distance between the center lines of the first two adjacent first electrode fingers in the middle area of the first IDT32 The distance is different from the distance between two adjacent second electrode fingers in the middle region of the second IDT 42 , which is similar to (1), and will not be repeated here.

In the first specific embodiment, the difference between the intermediate structure parameters of the first IDT32 intermediate area and the intermediate structure parameters of the second IDT42 intermediate area includes at least one of the following situations: the first left-order IDT intermediate area The middle structure parameter of an electrode finger 321 is different from the middle structure parameter of the second electrode finger 421 in the middle region of the first right-stage IDT; the middle structure parameter of the first electrode finger 321 in the middle region of the second left-step IDT is different from that of The intermediate structure parameters of the second electrode fingers 421 in the middle region of the second right-order IDT are different; The intermediate structure parameters of the second electrode fingers 421 are different; the intermediate structure parameters of the first electrode fingers 321 in the middle region of the fourth left-order IDT are different from the intermediate structure parameters of the second electrode fingers 421 in the middle region of the fourth right-order IDT The parameters are different; the middle structure parameters of the first electrode fingers 321 in the middle region of the fifth left-level IDT are different from the middle structure parameters of the second electrode fingers 421 in the middle region of the fifth right-step IDT.

The difference in the first structure parameter also includes that the edge structure parameters of the edge regions on both sides of the first IDT32 are different from those of the edge regions on both sides of the second IDT42. It can be understood that the first electrode fingers 321 in the middle area are removed in the first IDT32, and the remaining are the first electrode fingers 321 in the edge areas on both sides; the edge areas are distributed by the first electrode fingers 321 in the first IDT32. Smaller areas. As shown in FIG. 1 , for example, when the first IDT 32 includes seven first electrode fingers 321 , its two side edge regions include two outer first electrode fingers 321 . The structural parameters of the edge regions on both sides of the second IDT42 are similar to the structural parameters of the first IDT32, and will not be repeated here. It can be understood that the difference in the edge structure parameters is similar to the difference in the middle structure parameters, and will not be repeated here.

In the first specific embodiment, the difference between the first structural parameters of the edge regions on both sides of the first IDT32 and the edge structural parameters of the edge regions on both sides of the second IDT42 includes at least one of the following situations: the first left-order The edge structure parameters of the first electrode fingers 321 in the edge regions on both sides of the IDT are different from the edge structure parameters of the second electrode fingers 421 in the edge regions on both sides of the first right-order IDT; The edge structure parameters of the first electrode fingers 321 are different from the edge structure parameters of the second electrode fingers 421 in the edge regions on both sides of the second right-stage IDT; the first electrode fingers in the edge regions on both sides of the third left-stage IDT The edge structure parameters of 321 are different from the edge structure parameters of the second electrode fingers 421 in the edge regions on both sides of the third right-order IDT; the edge structure parameters of the first electrode fingers 321 in the edge regions on both sides of the fourth left-order IDT Different from the edge structure parameters of the second electrode fingers 421 in the edge regions on both sides of the fourth right-stage IDT; the edge structure parameters of the first electrode fingers 321 in the edge regions on both sides of the fifth left-stage IDT are different from the The edge structure parameters of the second electrode fingers 421 in the edge areas on both sides of the right-stage IDT are different.

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 IDT42.

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

The distance between the centerlines of two adjacent reflective electrode fingers of the first reflector is greater than the distance between the centerlines of two adjacent reflective electrode fingers of the second reflector.

Dotted line in Fig. 4 is the passband insertion loss diagram in the prior art (the first DMS type structure parameter is the same as the second DMS type structure parameter), and solid line among Fig. 4 is that the first IDT described in the present invention is adjacent two The distance between the centerlines of electrode fingers is greater than the distance between the centerlines of two adjacent electrode fingers of the second IDT, and the distance between the centerlines of two adjacent reflective electrode fingers of the first reflector The passband insertion loss diagram when greater than the distance between the centerlines of two adjacent reflective electrode fingers of the second reflector; by comparing the solid line and the dashed line in Figure 4, it can be clearly shown that the filter of the present invention has wider passband.

Dotted line in Fig. 5 is the out-of-band suppression figure in the prior art (the first DMS type structure parameter is the same as the second DMS type structure parameter), and solid line in Fig. 5 is the adjacent two electrodes of the first IDT described in the present invention The distance between the centerlines of the fingers is greater than the distance between the centerlines of two adjacent electrode fingers of the second IDT, and the distance between the centerlines of two adjacent reflective electrode fingers of the first reflector is greater than The out-of-band suppression figure when the distance between the centerlines of two adjacent reflective electrode fingers of the second reflector; by comparing the solid line and the dotted line in Fig. 5, it can be clearly shown that the filter of the present invention has better Out-of-band suppression effect.

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

In one embodiment, in the first IDT 32 , the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides thereof. That is to say, in the first IDT32, the distance between the centerlines of two adjacent first electrode fingers 321 in the middle area is larger than the centers of the two adjacent first electrode fingers 321 in the edge areas on both sides. distance between lines.

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

In an embodiment, in the second IDT 42 , the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides. That is, in the second IDT42, the distance between the centerlines of two adjacent second electrode fingers 421 in the central area is larger than the centers of the adjacent two second electrode fingers 421 in the edge areas on both sides. distance between lines.

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

Another embodiment of the present invention also provides a multiplexer, including the above-mentioned filter.

Yet another embodiment of the present invention also provides a radio frequency front end, including the above-mentioned filter.

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

Claims (10)

1. A filter, characterized in that it comprises a plurality of DMS type filters connected in parallel, a plurality of DMS type filters comprising a first DMS type filter and a second DMS type filter; The first DMS type filter includes two first reflectors arranged oppositely and a plurality of first IDTs located between the two first reflectors; The second DMS type 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 the structural parameters of the second DMS filter. 2. The filter according to claim 1, wherein 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 following situations: 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 according to claim 2, wherein the first IDT and the second IDT each comprise two comb electrodes arranged in parallel, and the electrode fingers of the two comb electrodes intersect each other Arrangement, the first structural parameter includes at least one of the distance between the centerlines of two adjacent electrode fingers, the number of electrode fingers, and the aperture of the IDT. 4. The filter according to claim 2, wherein the first reflector and the second reflector both include a plurality of reflective electrode fingers distributed at intervals, and the second structural parameters include two adjacent The distance between the centerlines of reflective electrode fingers and/or the number of reflective electrode fingers. 5. The filter according to claim 2, wherein the first structural parameters of the first IDT and the second IDT are different, including: The middle structure parameters of the first IDT middle region and the second IDT middle region are different, and the middle structure parameters include the number of electrode fingers in the middle region and/or the distance between the centerlines of two adjacent electrode fingers in the middle region; and / or The edge structure parameters of the edge areas on both sides of the first IDT are different from those of the edge areas on both sides of the second IDT, and the edge structure parameters include the number of electrode fingers in the edge area and/or the distance between the centerlines of two adjacent electrode fingers in the edge area. distance between. 6. The filter according to any one of claims 2-5, wherein the first structural parameters of the first IDT and the second IDT are different, including: The distance between the centerlines of two adjacent electrode fingers of the first IDT is greater than the distance between the centerlines of two adjacent electrode fingers of the second IDT; The second structural parameters of the first reflector and the second reflector are different, including: The distance between the centerlines of two adjacent reflective electrode fingers of the first reflector is greater than the distance between the centerlines of two adjacent reflective electrode fingers of the second reflector. 7. The filter of claim 1, wherein a plurality of said DMS-type filters have unbalanced outputs. 8. The filter of claim 2, wherein In the first IDT, the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides; and/or In the second IDT, the distance between the centerlines of two adjacent electrode fingers in the middle region is greater than the distance between the centerlines of two adjacent electrode fingers in the edge regions on both sides. 9. A multiplexer, comprising the filter according to any one of claims 1-8. 10. A radio frequency front end, comprising the filter according to any one of claims 1-8.