Surface acoustic wave filters and radio frequency front-end module

Abstract

Surface acoustic wave filters and a radio frequency front-end module. A surface acoustic wave filter comprises a plurality of resonators. The plurality of resonators at least comprise two groups of resonators of different resonant frequencies, i.e. a first group of resonators and a second group of resonators, the length of a first gap area of the first group of resonators in a first direction being different from the length of a first gap area of the second group of resonators in the first direction, such that the effect of a spurious mode generated by non-intersection areas of the plurality of resonators on a passband is avoided, so as to optimize the performance of the surface acoustic wave filter.

Description

Surface acoustic wave filter and radio frequency front-end module TECHNICAL FIELD

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

[0002] A surface acoustic wave (SAW) resonator is a device that converts an electrical signal into an acoustic signal or converts an acoustic signal into an electrical signal. The SAW resonator generally includes a piezoelectric substrate and an interdigital transducer (IDT) formed on the piezoelectric substrate, which can be used to convert an electrical signal into an acoustic signal or convert an acoustic signal into an electrical signal.

[0003] In some SAW resonators, the SAW resonator generates a spurious mode, which has a great influence on the passband of the filter, and deteriorates the performance of the filter. SUMMARY

[0004] The present application aims to provide a surface acoustic wave filter and a radio frequency front-end module, which aims to reduce the influence of the spurious mode on the passband of the surface acoustic wave filter.

[0005] To achieve the above-mentioned purpose, the present application provides a surface acoustic wave filter, comprising: an input terminal, an output terminal, and a plurality of resonators connected between the input terminal and the output terminal.

[0006] The resonator includes an interdigital transducer, the interdigital transducer includes: two bus bars arranged in parallel and at intervals, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are respectively connected with one of the two bus bars, and the plurality of electrode fingers connected to different bus bars are arranged at intervals and alternately along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, the non-intersection region includes a first gap region; wherein the intersection region is a region in which the plurality of electrode fingers overlap each other.

[0007] The plurality of resonators at least includes a first group of resonators and a second group of resonators, the resonant frequency of the first group of resonators is different from the resonant frequency of the second group of resonators, and the length of the first gap region of the first group of resonators in a first direction is different from the length of the first gap region of the second group of resonators in the first direction; wherein the first direction is the direction in which the two bus bars are arranged oppositely.

[0008] To achieve the above object, the application further provides a surface acoustic wave filter, comprising: an input terminal, an output terminal and a plurality of resonators connected between the input terminal and the output terminal;

[0009] The resonator comprises an interdigital transducer, the interdigital transducer comprises: two bus bars arranged in parallel and at intervals, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are connected with one of the two bus bars respectively, and the plurality of electrode fingers connected with different bus bars are arranged at intervals and alternately along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, and the non-intersection region is provided with a first gap region; wherein the intersection region is an area where the plurality of electrode fingers overlap with each other.

[0010] The plurality of resonators comprise a plurality of series arm resonators and a plurality of parallel arm resonators, the length of the first gap region of the plurality of series arm resonators along a first direction is different from the length of the first gap region of the plurality of parallel arm resonators along the first direction; wherein the first direction is the direction in which the two bus bars are arranged oppositely.

[0011] To achieve the above object, the application further provides a surface acoustic wave filter, comprising: an input terminal, an output terminal and a plurality of resonators connected between the input terminal and the output terminal;

[0012] The resonator comprises an interdigital transducer, the interdigital transducer comprises: two bus bars arranged in parallel and at intervals, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are connected with one of the two bus bars respectively, and the plurality of electrode fingers connected with different bus bars are arranged at intervals and alternately along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, and the non-intersection region is provided with a first gap region; wherein the intersection region is an area where the plurality of electrode fingers overlap with each other.

[0013] The plurality of resonators comprise a plurality of series arm resonators and a plurality of parallel arm resonators, the length of the first gap region of the plurality of series arm resonators along a first direction is different from the length of the first gap region of the plurality of parallel arm resonators along the first direction; wherein the first direction is the direction in which the two bus bars are arranged oppositely.

[0014] The application further provides a radio frequency front end module, comprising the surface acoustic wave filter according to any one of the above.

[0015] In the surface acoustic wave filter and the radio frequency front end module provided by the application, the length of the first gap region of the first group of resonators in the first direction is set to be different from the length of the first gap region of the second group of resonators in the first direction, so that the spurious mode generated by the non-crossing region of the plurality of resonators has no influence on the passband, and the performance of the surface acoustic wave filter is optimized. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to the structures shown in the drawings without creative labor for those skilled in the art.

[0017] FIG. 1 is a Q value curve of a surface acoustic wave resonator in the prior art;

[0018] FIG. 2 is a structure topology diagram of a surface acoustic wave filter;

[0019] FIG. 3 is a structure schematic diagram of a resonator;

[0020] FIG. 4 is a structure schematic diagram of a resonator;

[0021] FIG. 5 is a Q value curve of a resonator of a surface acoustic wave filter in the prior art;

[0022] FIG. 6 is a Q value curve of a resonator of a surface acoustic wave filter provided by the embodiments of the present application;

[0023] FIG. 7 is a structure schematic diagram of an interdigital transducer of a surface acoustic wave filter provided by the embodiments of the present application;

[0024] FIG. 8 is a structure schematic diagram of an interdigital transducer of a surface acoustic wave filter provided by the embodiments of the present application;

[0025] FIG. 9 is a structure schematic diagram of an interdigital transducer of a surface acoustic wave filter provided by the embodiments of the present application;

[0026] FIG. 10 is a structure schematic diagram of an interdigital transducer of a surface acoustic wave filter provided by the embodiments of the present application;

[0027] FIG. 11 is a structure schematic diagram of an interdigital transducer of a surface acoustic wave filter provided by the embodiments of the present application;

[0028] FIG. 12 is a structure schematic diagram of a surface acoustic wave filter provided by the embodiments of the present application;

[0029] FIG. 13 is a structure schematic diagram of a surface acoustic wave filter provided by the embodiments of the present application;

[0030] Fig. 14 is a third structural schematic diagram of a surface acoustic wave filter according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0032] The influence of the spurious mode generated in the non-crossing area of the surface acoustic wave resonator on the resonator is increasingly non-negligible. As shown in Fig. 1, the figure shows the relationship between the real part of admittance and Q value and frequency of two surface acoustic wave resonators, wherein the abscissa is frequency, and the gray intervals in the figure are the regions of the spurious mode generated in the non-crossing area of the two surface acoustic wave resonators, respectively. It can be clearly seen from the figure that the spurious mode generated in the non-crossing area of the surface acoustic wave resonator will significantly reduce the Q value. In the filter containing the above surface acoustic wave resonator, if the spurious mode generated in the non-crossing area of the surface acoustic wave resonator is located in the passband of the filter, it will obviously have a greater impact on the passband of the filter, and will worsen the insertion loss.

[0033] As shown in Fig. 2, in the structure of the surface acoustic wave filter, the surface acoustic wave filter comprises an input terminal a, an output terminal b, and a plurality of resonators 100 connected between the input terminal a and the output terminal b. The plurality of resonators 100 can comprise a plurality of series-connected resonators 100 and / or a plurality of parallel-connected resonators 100. One end of the parallel-connected resonator 100 is connected to the series-connected resonator 100, and the other end is connected to the ground terminal c. At least one parallel-connected resonator 100 can be arranged between adjacent series-connected resonators 100, without limitation. For example, in Fig. 2, one parallel-connected resonator 100 is arranged between every two adjacent series-connected resonators 100.

[0034] As shown in Fig. 3, in the above-mentioned surface acoustic wave filter, the resonator 100 comprises a piezoelectric substrate 20 and an interdigital transducer 10 arranged on the piezoelectric substrate 20. The piezoelectric substrate 20 is made of piezoelectric material, such as quartz, lithium niobate, lithium tantalate, AlN, etc. In addition, at least one dielectric layer 30 is arranged on the piezoelectric substrate 20, and the dielectric layer 30 covers the interdigital transducer 10. The dielectric layer 30 can be used to protect the interdigital transducer 10, for example, the dielectric layer 30 is a passivation layer. The dielectric layer 30 can also be used to achieve the effect of temperature compensation and adjust the acoustic velocity to a certain extent, for example, the dielectric layer 30 can be a silicon dioxide layer.

[0035] In some embodiments, the piezoelectric substrate 20 can be a single-layer piezoelectric structure or a multi-layer piezoelectric structure. For example, the piezoelectric substrate 20 includes a substrate and a piezoelectric film stacked together, the interdigital transducer 10 is disposed on a surface of the piezoelectric film away from the substrate, the thickness of the substrate is greater than the thickness of the piezoelectric film, and the temperature coefficient of the substrate is less than the temperature coefficient of the piezoelectric film. Other medium layers can be disposed between the substrate and the piezoelectric film, the thickness of each of the other medium layers and the piezoelectric film is less than the thickness of the substrate, and the acoustic velocity of each of the piezoelectric film and the substrate is greater than the acoustic velocity of each of the other medium layers. The substrate can be made of silicon, quartz, sapphire, silicon carbide, or the like.

[0036] As shown in FIG. 4, the interdigital transducer 10 includes two bus bars 11 arranged in parallel and at intervals, and a plurality of electrode fingers 12 disposed between the two bus bars 11. The plurality of electrode fingers 12 are respectively connected to one of the two bus bars 11, and the plurality of electrode fingers 12 connected to different bus bars 11 are arranged at intervals and alternately along the length direction of the bus bar 11. The two bus bars 11 form a crossing region R1 therebetween, and a non-crossing region R2 between the crossing region R1 and the two bus bars 11. The crossing region R1 is a region in which the plurality of electrode fingers 12 overlap each other.

[0037] In addition, the resonator 100 can further include a reflective grid 40 disposed on the piezoelectric substrate 20. The reflective grid 40 is disposed on both sides of the interdigital transducer 10 along the propagation direction of the acoustic wave to prevent leakage of the surface acoustic wave, thereby improving the performance of the resonator.

[0038] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The following examples and features in the examples can be combined with each other without conflict.

[0039] As shown in FIGS. 2 and 4-11, the present application provides a surface acoustic wave filter including a plurality of resonators 100. The resonator 100 includes an interdigital transducer 10, and the non-crossing region R2 of the interdigital transducer includes a first gap region d1.

[0040] The plurality of resonators 100 include at least a first group of resonators and a second group of resonators. The resonant frequency of the first group of resonators is different from the resonant frequency of the second group of resonators, and the length of the first gap region d1 of the first group of resonators along a first direction A is different from the length of the first gap region d1 of the second group of resonators along the first direction A. The first direction A is the direction in which the two bus bars 11 are arranged oppositely.

[0041] It should be noted that among the plurality of resonators 100, there are resonators 100 whose resonant frequencies are within the passband and resonators 100 whose anti-resonant frequencies are within the passband, thereby enabling the surface acoustic wave filter to form a passband. The resonators 100 whose resonant frequencies are within the passband can be resonators 100 in the first group of resonators, resonators 100 in the second group of resonators, or resonators 100 other than the first group of resonators or the second group of resonators, without limitation. Similarly, the resonators 100 whose anti-resonant frequencies are within the passband can be resonators 100 in the first group of resonators, resonators 100 in the second group of resonators, or resonators 100 other than the first group of resonators or the second group of resonators, without limitation.

[0042] It can be understood that when the resonant frequencies of the first group of resonators are different from the resonant frequencies of the second group of resonators, the length of the first gap region d1 of the first group of resonators along the first direction A can be greater than or less than the length of the first gap region d1 of the second group of resonators along the first direction A.

[0043] In this embodiment, the first gap region d1 is located in the non-intersection region R2. It can be understood that the first gap region d1 can be the non-intersection region R2 or a part of the non-intersection region R2.

[0044] It should be noted that as the Q value of the resonator 100 increases, the influence of the spurious mode generated by the non-crossing region R2 on the performance of the resonator 100 becomes more and more obvious, and the change in the length of the first gap region d1 in the non-crossing region R2 in the first direction A affects the position of the spurious mode generated by the non-crossing region R2 on the admittance curve of the resonator. Generally, the first gap region d1 of each resonator 100 of the surface acoustic wave filter has the same length, and in the design, in order to make the spurious mode generated by the non-crossing region R2 not seriously affect the passband performance of the surface acoustic wave filter, the length of the first gap region d1 is adjusted to a suitable position. In this case, if there are a first group of resonators and a second group of resonators with different frequencies, and the lengths of the first gap regions d1 of the first group of resonators and the second group of resonators along the first direction A are consistent, then in the first group of resonators and the second group of resonators, there may be a group of resonators 100 whose spurious mode is located in the passband of the surface acoustic wave filter, which leads to the performance degradation of the surface acoustic wave filter. As shown in FIG. 5, the arch-shaped curve (thick solid line) is the passband of the surface acoustic wave filter, and the curves 1 and 2 are the Q value curves of two groups of resonators 100 with different resonant frequencies, wherein the resonant frequency of the resonator 100 corresponding to the curve 1 is in the passband, and the anti-resonant frequency of the resonator 100 corresponding to the curve 2 is in the passband, and the horizontal coordinate is the frequency. The lengths of the first gap regions d1 of the two groups of resonators 100 along the first direction A are the same, and as can be seen from FIG. 5, the shaded area is the position of the spurious mode of the resonator 100 corresponding to the curve 1, which is located in the passband of the surface acoustic wave filter, so the passband at the position of the shaded area is recessed, which reduces the insertion loss of the filter.

[0045] Generally, in the case where the lengths of the first gap regions d1 of the two groups of resonators 100 along the first direction A remain consistent, if the spurious mode of the first group of resonators is moved to the high frequency side outside the passband by changing the length of the first gap region d1 along the first direction A, then the spurious mode of the second group of resonators will also move to the high frequency side, which may cause the spurious mode of the second group of resonators to be located in the passband, thereby affecting the passband performance of the surface acoustic wave filter.

[0046] In the surface acoustic wave filter of the embodiment of the present application, in the first group of resonators and the second group of resonators with different resonant frequencies, the lengths of the first gap regions d1 of the two groups of resonators along the first direction A are adjusted respectively, so that the length of the first gap region d1 of the first group of resonators along the first direction A is different from the length of the first gap region d1 of the second group of resonators along the first direction A, thereby the spurious mode generated by the first group of resonators and the spurious mode generated by the second group of resonators can be moved outside the passband, thereby avoiding the influence of the spurious mode generated by the non-crossing region R2 of the resonator 100 on the passband, and optimizing the performance of the surface acoustic wave filter.

[0047] It should be noted that the passband of the surface acoustic wave filter refers to a frequency band through which signals can pass, and the passband includes a transition band and a stopband, the transition band is located between the passband and the stopband, and the high frequency side of the passband in the embodiment of the application refers to the high frequency side of the passband or the high frequency transition band; the low frequency side of the passband refers to the low frequency side of the passband or the low frequency transition band.

[0048] Further, as shown in FIG. 6, the arch-shaped curve (thick solid line) is the passband of the surface acoustic wave filter, and curve 1 and curve 2 are Q value curves of two groups of resonators 100 with different resonant frequencies, wherein curve 1 corresponds to the resonant frequency of the resonator 100 in the passband, and curve 2 corresponds to the anti-resonant frequency of the resonator 100 in the passband, the abscissa is the frequency, and the length of the first gap region d1 of the resonator corresponding to curve 1 along the first direction A is greater than the length of the first gap region d1 of the resonator corresponding to curve 2 along the first direction A. As can be seen from FIG. 5, the passband of the surface acoustic wave filter in FIG. 6 does not produce a depression corresponding to the shaded area in FIG. 5, thereby improving the passband performance of the surface acoustic wave filter.

[0049] In the embodiment of the application, the length of the first gap region d1 of the resonator 100 along the first direction A is positively correlated with the position of the spurious mode on the Q value curve, that is, the spurious mode can be moved to the high frequency side by increasing the length of the first gap region d1 along the first direction A, and the spurious mode can be moved to the low frequency side by reducing the length of the first gap region d1 along the first direction A. For example, the spurious mode can be moved to the high frequency side of the passband by increasing the length of the first gap region d1 along the first direction A, and the spurious mode can be moved to the low frequency side of the passband by reducing the length of the first gap region d1 along the first direction A, so as to avoid the influence of the spurious mode generated by the non-intersection region R2 on the passband, and further optimize the performance of the surface acoustic wave filter.

[0050] In some embodiments, the resonant frequency or the anti-resonant frequency of the resonator in at least one of the first group of resonators and the second group of resonators is in the passband of the surface acoustic wave filter. In this way, the basic filtering function can be achieved, for example, the signal in the frequency range is enhanced or attenuated, and it is ensured that the signal can pass in a certain frequency range. Moreover, the lengths of the first gap regions d1 of the two groups of resonators 100 along the first direction A are set to be different, so that the length of the first gap region d1 of one group or both groups along the first direction A can be adjusted to make the spurious mode generated by the first group of resonators and the spurious mode generated by the second group of resonators be located outside the passband, thereby avoiding the influence of the spurious mode generated by the non-intersection region R2 of the multiple resonators 100 on the passband, and optimizing the performance of the surface acoustic wave filter.

[0051] In some embodiments, the resonant frequencies of the first set of resonators and the second set of resonators are both within the passband. Then, in the case that the resonant frequencies of the first set of resonators and the second set of resonators are different, by adjusting the length of the first gap region dl of the first set of resonators along the first direction A such that the length of the first gap region dl of the first set of resonators along the first direction A is different from the length of the first gap region dl of the second set of resonators along the first direction A, the spurious modes of the first set of resonators and the spurious modes of the second set of resonators can both be located at the high frequency side of the passband of the surface acoustic wave filter. It can be understood that, in this case, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, and in some embodiments, can also be equal to the length of the first gap region dl of the second set of resonators along the first direction A, and the present application does not make any limitation. In the present embodiment, the resonant frequencies of the first set of resonators and the second set of resonators are both within the passband, and then the anti-resonant frequencies of the first set of resonators and the second set of resonators are located at the high frequency side of the passband, and the present application can move the spurious modes of the first set of resonators and the spurious modes of the second set of resonators to the high frequency side of the passband by increasing the length of the first gap region dl of the first set of resonators and the second set of resonators along the first direction A, so as to avoid the spurious modes generated by the first set of resonators and the second set of resonators from affecting the passband of the surface acoustic wave filter, so as to improve the performance of the surface acoustic wave filter.

[0052] In some embodiments, the anti-resonance frequency of the first set of resonators and the anti-resonance frequency of the second set of resonators are both within the passband. Then, in the case that the resonance frequency of the first set of resonators and the resonance frequency of the second set of resonators are different, by adjusting the length of the first gap region dl of the first set of resonators along the first direction A such that the length of the first gap region dl of the first set of resonators along the first direction A is different from the length of the first gap region dl of the second set of resonators along the first direction A, the spurious modes of the first set of resonators and the spurious modes of the second set of resonators can both be located at the low frequency side of the passband of the surface acoustic wave filter. It can be understood that, in this case, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, and in some embodiments, can also be equal to the length of the first gap region dl of the second set of resonators along the first direction A, which is not limited by the present application. In the present embodiment, the anti-resonance frequency of the first set of resonators and the anti-resonance frequency of the second set of resonators are both within the passband, and then the resonance frequency of the first set of resonators and the resonance frequency of the second set of resonators are located at the low frequency side of the passband. The present application can move the spurious modes of the first set of resonators and the spurious modes of the second set of resonators to the low frequency side of the passband by reducing the length of the first gap region dl of the first set of resonators and the second set of resonators along the first direction A, so as to avoid the spurious modes generated by the first set of resonators and the second set of resonators from affecting the passband of the surface acoustic wave filter, thereby improving the performance of the surface acoustic wave filter.

[0053] In some embodiments, the resonance frequency of the first set of resonators is greater than the resonance frequency of the second set of resonators, and the length of the first gap region dl of the first set of resonators along the first direction A is greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A.

[0054] For example, the resonance frequency of the first set of resonators and the resonance frequency of the second set of resonators are both within the passband, and at this time, the anti-resonance frequency of the first set of resonators and the anti-resonance frequency of the second set of resonators are located at the high frequency side of the passband. The spurious modes of the first set of resonators and the spurious modes of the second set of resonators can be moved to the high frequency side of the passband by increasing the length of the first gap region dl of the first set of resonators and the second set of resonators along the first direction A, so as to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious modes generated by the non-intersection region R2 can be moved to the high frequency side of the passband, which is not limited by the present application.

[0055] In yet some examples, the anti-resonance frequency of the first set of resonators and the anti-resonance frequency of the second set of resonators are both within the passband, and the resonance frequency of the first set of resonators is greater than the resonance frequency of the second set of resonators, in which case the resonance frequency of the first set of resonators and the resonance frequency of the second set of resonators are both outside the passband on the low frequency side, the spurious modes of the first set of resonators and the spurious modes of the second set of resonators can be moved to the low frequency side of the passband by reducing the length of the first gap region dl of the first set of resonators and the second set of resonators along the first direction A, to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious modes generated by the non-crossing region R2 can be moved to the low frequency side of the passband, without limitation.

[0056] In yet some examples, the resonance frequency of the first set of resonators is outside the passband on the high frequency side, and the resonance frequency of the second set of resonators is within the passband, in which case the anti-resonance frequency of the second set of resonators is outside the passband on the high frequency side, and the spurious modes generated by the non-crossing region R2 of the first set of resonators are outside the passband, without affecting the passband, the spurious modes of the second set of resonators can be moved to the high frequency side of the passband by increasing the length of the first gap region dl of the second set of resonators along the first direction A, to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious modes generated by the non-crossing region R2 of the second set of resonators can be moved to the high frequency side of the passband, without limitation.

[0057] In yet some examples, the resonance frequency of the first set of resonators is outside the passband on the high frequency side, and the anti-resonance frequency of the second set of resonators is within the passband, in which case the resonance frequency of the second set of resonators is outside the passband on the low frequency side, and the spurious modes generated by the non-crossing region R2 of the first set of resonators are outside the passband, without affecting the passband, the spurious modes of the second set of resonators can be moved to the low frequency side of the passband by reducing the length of the first gap region dl of the second set of resonators along the first direction A, to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious modes generated by the non-crossing region R2 of the second set of resonators can be moved to the low frequency side of the passband, without limitation.

[0058] In yet some examples, the resonant frequency of the first set of resonators is located in the passband, the anti-resonant frequency of the second set of resonators is located at the low frequency side of the passband, at this time, the anti-resonant frequency of the first set of resonators is located at the high frequency side of the passband, the non-crossing region R2 of the second set of resonators generates a spurious mode itself located at the high frequency side of the passband, which does not affect the passband, and the length of the first gap region dl of the first set of resonators along the first direction A can be increased to move the spurious mode of the first set of resonators to the high frequency side of the passband to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious mode generated by the non-crossing region R2 of the first set of resonators can be moved to the high frequency side of the passband, which is not limited.

[0059] In yet some examples, the anti-resonant frequency of the first set of resonators is located in the passband, the anti-resonant frequency of the second set of resonators is located at the low frequency side of the passband, at this time, the resonant frequency of the first set of resonators is located at the low frequency side of the passband, the non-crossing region R2 of the second set of resonators generates a spurious mode itself located at the low frequency side of the passband, which does not affect the passband, and the length of the first gap region dl of the first set of resonators along the first direction A can be reduced to move the spurious mode of the first set of resonators to the low frequency side of the passband to improve the performance of the surface acoustic wave filter. In this example, the length of the first gap region dl of the first set of resonators along the first direction A can be greater than or less than the length of the first gap region dl of the second set of resonators along the first direction A, as long as the spurious mode generated by the non-crossing region R2 of the first set of resonators can be moved to the low frequency side of the passband, which is not limited.

[0060] In some examples, the resonant frequency of the first set of resonators is located in the passband of the surface acoustic wave filter, the anti-resonant frequency of the second set of resonators is located in the passband of the surface acoustic wave filter, and the length of the first gap region dl of the first set of resonators along the first direction A is greater than the length of the first gap region dl of the second set of resonators along the first direction A. In this example, the length of the first gap region dl of the first set of resonators along the first direction A is set to be greater than the length of the first gap region dl of the second set of resonators along the first direction A, so that the spurious mode of the first set of resonators is located at the high frequency side, and the spurious mode of the second set of resonators is located at the low frequency side, so as to adjust the spurious mode generated by the non-crossing region R2 of the first set of resonators and the spurious mode generated by the non-crossing region R2 of the second set of resonators respectively, so that the spurious mode generated by the first set of resonators and the spurious mode generated by the second set of resonators are located outside the passband to improve the performance of the surface acoustic wave filter.

[0061] In the above embodiments, the spurious modes of the first group of resonators are located at the high frequency side of the passband of the surface acoustic wave filter, and the spurious modes of the second group of resonators are located at the low frequency side of the passband of the surface acoustic wave filter. In this way, the spurious modes generated by the first group of resonators and the second group of resonators do not affect the passband of the surface acoustic wave filter, and the performance of the surface acoustic wave filter is improved. Specifically, on the basis of the above embodiments, the length of the first gap region d1 of the first group of resonators along the first direction A can be increased to move the spurious modes of the first group of resonators to the high frequency side until the spurious modes are located at the high frequency side of the passband, and the length of the first gap region d1 of the second group of resonators along the first direction A can be reduced to move the spurious modes of the second group of resonators to the low frequency side until the spurious modes are located at the low frequency side of the passband.

[0062] Exemplarily, the resonant frequency of the first group of resonators is greater than the anti-resonant frequency of the second group of resonators. In this way, the rectangularity of the surface acoustic wave filter can be increased. Of course, in other examples, the resonant frequency of the first group of resonators can also be less than the anti-resonant frequency of the second group of resonators, which is not described herein.

[0063] In other embodiments, the surface acoustic wave filter can further include a third group of resonators, and the resonant frequency and the anti-resonant frequency of the third group of resonators can be located at the low frequency side of the passband or at the high frequency side of the passband. In this case, the spurious modes generated by the non-intersection region R2 of the third group of resonators are located outside the passband and do not affect the passband of the surface acoustic wave filter, and therefore, the length of the first gap region d1 of the third group of resonators along the first direction A does not need to be adjusted.

[0064] It should be noted that in the plurality of resonators of the present application, the first group of resonators and the second group of resonators are described mainly for comparison of different resonators 100 in the plurality of resonators 100, that is, when only two different groups of resonators 100 are provided, any one of the setting modes of the first group of resonators and the second group of resonators in the above embodiments can be referred to, and when more different groups of resonators 100 are provided, at least two groups of resonators 100 are present, and the setting modes of the first group of resonators and the second group of resonators in the above embodiments can be referred to. In the present application, the specific functional requirements of the surface acoustic wave filter can be set without limitation.

[0065] As shown in FIG. 4, the first gap region d1 is the non-intersection region R2. As shown in FIGS. 7-11, the first gap region d1 is part of the non-intersection region R2.

[0066] In some embodiments, the length of the first gap region dl along the first direction A is 0.1λ-4.6λ, where λ represents the pitch of adjacent electrode fingers 12 connected to the same bus bar 11. For example, it can be 0.1λ, 0.5λ, 1λ, 2λ, 3λ, 4λ, 4.6λ, etc. Setting the length of the first gap region dl along the first direction A to be at least 0.1λ can ensure that the crossover region R1 and the bus bar 11 have sufficient spacing, avoiding uneven electric field distribution and affecting the generation and propagation of surface acoustic waves. Setting the length of the first gap region dl along the first direction A to be at least 4.6λ can avoid energy loss and signal attenuation, ensuring the efficiency of the resonator. In the present embodiment, the length of the first gap region dl along the first direction A of the first group of resonators and the second group of resonators is within the range of 0.1λ-4.6λ, and when the resonant frequency of the first group of resonators and the resonant frequency of the second group of resonators are different, adjusting the length of the first gap region dl along the first direction A of the first group of resonators and the second group of resonators can make the length of the first gap region dl along the first direction A of the first group of resonators and the second group of resonators different, so that the spurious modes of the first group of resonators and the second group of resonators are both located outside the passband of the surface acoustic wave filter, avoiding the influence of spurious modes generated in the non-crossover region R2 on the passband, and further optimizing the performance of the surface acoustic wave filter.

[0067] In some specific embodiments, among the first group of resonators and the second group of resonators, the length of the first gap region dl along the first direction A of the group of resonators with longer length can be 0.5λ-4.6λ, and the length of the first gap region dl along the first direction A of the group of resonators with shorter length can be 0.1λ-0.5λ. For example, the length of the first gap region dl along the first direction A of the second group of resonators can be 0.1λ, 0.2λ, 0.3λ, 0.4λ, 0.5λ, etc., the length of the first gap region dl along the first direction A of the first group of resonators can be 0.5λ, 1λ, 2λ, 3λ, 4λ, 4.6λ, etc., and the length of the first gap region dl along the first direction A of the first group of resonators and the second group of resonators is different.

[0068] In the embodiment, the length of the first gap region dl of the first group of resonators along the first direction A is greater than the length of the first gap region dl of the second group of resonators along the first direction A, which can make the spurious mode of the first group of resonators be on the high frequency side and the spurious mode of the second group of resonators be on the low frequency side. Further, according to reasonable settings, the spurious mode of the first group of resonators can be on the high frequency side out of the passband and the spurious mode of the second group of resonators can be on the low frequency side out of the passband, so as to avoid the spurious mode from affecting the passband of the surface acoustic wave filter and improve the performance of the surface acoustic wave filter on the basis of meeting the basic requirement of the length of the first gap region dl along the first direction A. Specifically, the resonant frequency of the first group of resonators can be located in the passband of the surface acoustic wave filter and the anti-resonant frequency of the second group of resonators can be located in the passband of the surface acoustic wave filter, so as to move the spurious mode out of the passband by adjusting the length of the first gap region dl along the first direction A.

[0069] For example, the resonant frequency of the first group of resonators and the resonant frequency of the second group of resonators are both located in the passband, the resonant frequency of the first group of resonators is greater than the resonant frequency of the second group of resonators, the length of the first gap region dl of the first group of resonators along the first direction A is 0.5λ-4.6λ, and the length of the first gap region dl of the second group of resonators along the first direction A is 0.5λ-4.6λ. In this way, according to reasonable settings, the spurious mode of the first group of resonators and the spurious mode of the second group of resonators can be moved to the high frequency side out of the passband, so as to avoid the spurious mode from affecting the passband of the surface acoustic wave filter and improve the performance of the surface acoustic wave filter. Specifically, the resonant frequency of the first group of resonators and the resonant frequency of the second group of resonators can be set in the passband, so as to move the spurious mode out of the passband by increasing the length of the first gap region dl along the first direction A.

[0070] For example, the anti-resonant frequency of the first group of resonators and the anti-resonant frequency of the second group of resonators are both located in the passband, the anti-resonant frequency of the first group of resonators is greater than the anti-resonant frequency of the second group of resonators, the length of the first gap region dl of the first group of resonators along the first direction A is 0.1λ-0.5λ, and the length of the first gap region dl of the second group of resonators along the first direction A is 0.1λ-0.5λ. In this way, according to reasonable settings, the spurious mode of the first group of resonators and the spurious mode of the second group of resonators can be moved to the low frequency side out of the passband, so as to avoid the spurious mode from affecting the passband of the surface acoustic wave filter and improve the performance of the surface acoustic wave filter. Specifically, the anti-resonant frequency of the first group of resonators and the anti-resonant frequency of the second group of resonators can be set in the passband, so as to move the spurious mode out of the passband by decreasing the length of the first gap region dl along the first direction A.

[0071] In some embodiments, the size of the cross-over region R1 in the first direction A is less than 20λ. In this way, the size of the cross-over region R1 in the first direction A can be avoided to be too large to avoid uneven distribution of electric field between adjacent electrode fingers 12 to avoid affecting the generation and propagation of surface acoustic wave.

[0072] As shown in FIGS. 7-11, in some embodiments, the non-cross-over region R2 further comprises a second gap region d2, the first gap region d1 and the second gap region d2 are located in the same cross-over region R1, and the first gap region d1 is closer to the bus bar 11 than the second gap region d2. It can be understood that the first gap region d1 of the present application is the region close to the bus bar 11 and has a certain interval with the cross-over region R1, and the second gap region d2 is the region close to the cross-over region R1. Therefore, the first gap region d1 is actually the region which has less effect on the cross-over region R1 and will not affect the vibration of the cross-over region R1. The existence of the first gap region d1 will cause the acoustic velocity between the two bus bars 11 to change, thus unnecessary signals or fluctuations will be generated, and the non-cross-over region R2 will generate spurious modes. The frequency of the spurious modes generated by the non-cross-over region R2 will be positively correlated with the length of the first gap region d1 along the first direction A, that is, the longer the length of the first gap region d1 along the first direction A, the higher the frequency of the spurious modes, and the shorter the length of the first gap region d1 along the first direction A, the lower the frequency of the spurious modes. In the present application, the position of the spurious modes can be adjusted by adjusting the length of the first gap region d1 along the first direction A, so that the spurious modes are located outside the passband, thereby avoiding the influence of the spurious modes on the passband to optimize the performance of the surface acoustic wave filter.

[0073] Specifically, as shown in FIGS. 7-9, in some embodiments, the electrode finger 12 includes a connecting portion 121, a main body portion 123, and an intermediate portion 122, the connecting portion 121 and the main body portion 123 both extend in the first direction A, the intermediate portion 122 extends in the arranging direction of the electrode finger 12, the connecting portion 121 and the main body portion 123 are connected to the intermediate portion 122 in the first direction A in a staggered manner, one end of the connecting portion 121 away from the intermediate portion 122 is connected to one bus bar 11, one end of the main body portion 123 away from the intermediate portion 122 is arranged in a spaced manner with another bus bar 11, and a first gap region d1 is formed between the intermediate portion 122 and one bus bar 11. In the interdigital transducer 10 of this structure, by bending the electrode finger 12 to form the above structure, compared with the resonator 100 without the bending structure, the spurious mode generated by the non-crossing region R2 of the single resonator 100 can be reduced, so as to reduce the influence of the spurious mode generated by the non-crossing region R2 on the passband when the spurious mode generated by the non-crossing region R2 is located in the passband. In this embodiment, the length of the connecting portion 121 can be adjusted to adjust the gap between the intermediate portion 122 and the bus bar 11 to which the corresponding electrode finger 12 is connected, and then the length of the first gap region d1 in the first direction A is adjusted to adjust the position of the spurious mode, so that the spurious mode is located outside the passband, thereby avoiding the influence of the spurious mode on the passband, and optimizing the performance of the surface acoustic wave filter.

[0074] As shown in FIGS. 7-9, for example, one end of the intermediate portion 122 is connected to the connecting portion 121, and the other end of the intermediate portion 122 is connected to the main body portion 123.

[0075] In another example, one end of the intermediate portion 122 protrudes from the connecting portion 121, the other end of the intermediate portion 122 is connected to the main body portion 123, and the connecting portion 121 is connected to a position between the one end and the other end of the intermediate portion 122.

[0076] In another example, one end of the intermediate portion 122 is connected to the connecting portion 121, the other end of the intermediate portion 122 protrudes from the main body portion 123, and the main body portion 123 is connected to a position between the one end and the other end of the intermediate portion 122.

[0077] In another example, one end of the intermediate portion 122 protrudes from the connecting portion 121, the other end of the intermediate portion 122 protrudes from the main body portion 123, and the connecting portion 121 and the main body portion 123 are connected to a position between the one end and the other end of the intermediate portion 122 in a staggered manner.

[0078] As shown in Fig. 8, in the above embodiment of the bent electrode finger 12, the interdigital transducer 10 further comprises a first dummy finger 13, the first dummy finger 13 is connected to the intermediate portion 122 and extends in the first direction A towards the crossing region R1, the first dummy finger 13 and the main body portion 123 are spaced apart along the length direction of the bus bar 11. It is to be understood that, in this embodiment, the first dummy finger 13 is arranged opposite to the main body portion 123 of the electrode finger 12 connected to the other bus bar 11 with a spacing therebetween, and the second gap region d2 is formed between the first dummy finger 13 and the main body portion 123 of the electrode finger 12 connected to the other bus bar 11. In this way, the second gap region d2 is further reduced by the first dummy finger 13, thereby reducing the potential difference therebetween, weakening the intensity of the excitation source at the gap region, thereby suppressing the secondary excitation of the excitation source, enabling the spurious mode to be sufficiently suppressed, reducing the influence of the spurious mode of the resonator 100 on the passband, and further optimizing the performance of the surface acoustic wave filter.

[0079] As shown in Fig. 8, in the same electrode finger 12, the first dummy finger 13 is located in the extension direction of the connecting portion 121, for example. In other examples, in the same electrode finger 12, the first dummy finger 13 and the connecting portion 121 are arranged in a staggered manner.

[0080] In other embodiments, the first dummy finger 13 is connected to the intermediate portion 122 and can also extend in the first direction A away from the crossing region R1, the first dummy finger 13 and the main body portion 123 are in a straight line along the length direction of the bus bar 11, and of course, can also be arranged in a staggered manner.

[0081] As shown in Fig. 9, in the above embodiment of the bent electrode finger 12, the interdigital transducer 10 further comprises a second dummy finger 14, one end of the second dummy finger 14 is connected to the bus bar 11, and the other end is arranged opposite to and spaced apart from the intermediate portion 122 adjacent to the bus bar 11, and the first gap region d1 is formed between the second dummy finger 14 and the intermediate portion 122 adjacent thereto. The second dummy finger 14 can further suppress the spurious mode generated at the non-crossing region R2. It is to be understood that the second dummy finger 14 is located between the intermediate portion 122 adjacent thereto and the bus bar 11 connected thereto, and has a spacing with the connecting portion 121 of the electrode finger 12 connected to the bus bar 11, and the second dummy finger 14 actually lengthens the bus bar 11 in the first direction A, so that the first gap region d1 is formed between the second dummy finger 14 and the intermediate portion 122 adjacent thereto. In the present application, each bus bar 11 is provided with a plurality of second dummy fingers 14, and the plurality of second dummy fingers 14 and the plurality of electrode fingers 12 are in one-to-one correspondence.

[0082] As shown in Fig. 9, in the same electrode finger 12, the second dummy finger 14 is located in the extension direction of the adjacent main body portion 123, for example. In other examples, in the same electrode finger 12, the second dummy finger 14 and the adjacent main body portion 123 are arranged in a staggered manner along the extension direction of the intermediate portion 122.

[0083] As shown in FIG. 10 and FIG. 11, in some embodiments, the interdigital transducer 10 further comprises two conductive parts 15, which extend along the length direction of the bus bar 11, and are respectively connected to the plurality of electrode fingers 12 connecting the two bus bars 11, and are respectively arranged in the two non-crossing regions R2, each conductive part 15 is spaced apart from the bus bar 11 and the crossing region R1, and the first gap region d1 is formed between the conductive part 15 and the corresponding bus bar 11. It can be understood that, in the structure shown in FIG. 10 and FIG. 11, the arrangement of the conductive part 15 is conducive to suppressing the spurious mode generated in the non-crossing region R2, thereby improving the performance of the resonator 100.

[0084] In other embodiments, for example, in the structure shown in FIG. 7-FIG. 9, a conductive part (not shown in the figure) can also be arranged between the intermediate part 122 and the bus bar 11 to further suppress the spurious mode generated in the non-crossing region R2, and then the first gap region d1 can be the region between the conductive part and the bus bar 11. It should be noted that, in the structure shown in FIG. 7-FIG. 9, the conductive part 15 is also connected to the voltage, and by arranging the conductive part 15, the distance between the conductive part and the crossing region R1 is reduced, so that the resistance can be reduced, thereby reducing the device loss and improving the transduction efficiency of the interdigital transducer 10.

[0085] In the present embodiment, the position of the conductive part 15 connected to the electrode finger 12 can be adjusted to adjust the gap between the conductive part 15 and the adjacent bus bar 11, and then the length of the first gap region d1 in the first direction A is adjusted to adjust the position of the spurious mode, so that the spurious mode is located outside the passband, thereby avoiding the influence of the spurious mode on the passband, and optimizing the performance of the surface acoustic wave filter.

[0086] In some embodiments, each non-crossing region R2 can further comprise a plurality of conductive parts, which can be connected to the electrode fingers 12 of the corresponding non-crossing region R2, for example, the plurality of conductive parts of each non-crossing region R2 are arranged in parallel and spaced apart in the first direction A; or, the plurality of conductive parts can also be spaced apart from the electrode fingers 12, for example, in a direction perpendicular to the first direction A and the length direction of the bus bar 11, the plurality of conductive parts of each non-crossing region R2 are spaced apart from the electrode fingers, and the plurality of conductive parts are arranged in parallel and spaced apart, for example, the conductive parts can be arranged above the dielectric layer 30; or, the plurality of conductive parts can also be partially connected to the electrode fingers 12 of the corresponding non-crossing region R2 and partially spaced apart from the electrode fingers 12. In the present embodiment, the first gap region d1 is formed between the conductive part closest to the crossing region R2 and the corresponding bus bar 11.

[0087] As shown in FIG. 10, in some embodiments, the conductive part 15 is a continuous conductive strip 151. In this embodiment, the interdigital transducer 10 is provided with two conductive strips 151, and each conductive strip 151 corresponds to a bus bar 11 and is connected to the plurality of electrode fingers 12 connected to the bus bar 11. The conductive strip 151 is an integral whole without being broken in the middle, and the plurality of electrode fingers 12 connected to the bus bar 11 are connected through the conductive strip 151, so as to integrate signals and enhance signal strength. Meanwhile, it is also convenient for forming and manufacturing.

[0088] As shown in FIG. 11, in other embodiments, the conductive part 15 includes a plurality of conductive segments 152, and the plurality of conductive segments 152 are discontinuously arranged in the length direction of the bus bar 11. In this embodiment, for the plurality of electrode fingers 12 connected to the same bus bar 11, one conductive segment 152 can be arranged to connect at least one electrode finger 12, and different conductive segments 152 are arranged at intervals. The plurality of conductive segments 152 are discontinuously arranged in the length direction of the bus bar 11, so as to isolate the signals of different electrode fingers 12 and avoid the capacitive coupling effect between the electrode fingers 12, which helps to reduce the generation of stray signals and improve the precision and accuracy of the resonator 100.

[0089] As shown in FIG. 11, for example, each conductive segment 152 connects one electrode finger 12 among the plurality of electrode fingers 12 connected to the same bus bar 11.

[0090] In other examples, each conductive segment 152 connects a plurality of electrode fingers 12 among the plurality of electrode fingers 12 connected to the same bus bar 11. For example, each conductive segment 152 connects two electrode fingers 12, or each conductive segment 152 connects three electrode fingers 12.

[0091] In other examples, at least part of the conductive segments 152 respectively connect different numbers of electrode fingers 12 among the plurality of electrode fingers 12 connected to the same bus bar 11. For example, part of the conductive segments 152 connect one electrode finger 12, part of the conductive segments 152 connect two electrode fingers 12, and part of the conductive segments 152 connect three electrode fingers 12.

[0092] In some embodiments, the cross-over region R1 includes a middle region and edge regions located on both sides of the middle region in the first direction A, and the edge regions are provided with mass additional structures so that the acoustic velocity of the edge regions is less than the acoustic velocity of the middle region. In the structures shown in FIGS. 4, 7-11, the mass additional structures are arranged in the edge regions, which can increase the mass load of the edge regions, reduce the acoustic velocity of the edge regions, and the acoustic velocity corresponding to the non-cross-over region R2 > the acoustic velocity corresponding to the middle region > the acoustic velocity corresponding to the edge regions, so that the acoustic velocity of the edge regions matches the acoustic velocity of the non-cross-over region R2 and the acoustic velocity of the middle region, thereby forming a piston mode, reducing the acoustic wave transverse mode of the resonator 100, helping to suppress the transverse mode, reducing the influence of the transverse mode on the passband, and further optimizing the performance of the surface acoustic wave filter. Further, the mass additional structures can include electrode finger widening structures, electrode finger thickening structures, and structures provided with dielectric strips, so that the acoustic velocity of the edge regions is less than the acoustic velocity of the middle region.

[0093] As shown in FIG. 12, in some embodiments, the plurality of resonators 100 includes a plurality of series arm resonators S and a plurality of parallel arm resonators P, the plurality of series arm resonators S are connected in series between the input terminal a and the output terminal b, one end of the parallel arm resonator P is connected with the series arm resonator S, and the other end is connected with the ground terminal c, the resonant frequency of the series arm resonator S is greater than the resonant frequency of the parallel arm resonator P, the first group of resonators includes at least one series arm resonator S, the second group of resonators includes at least one parallel arm resonator P, the length of the first gap region d1 of the first group of resonators along the first direction A is greater than the length of the first gap region d1 of the second group of resonators along the first direction A. It should be noted that the series arm resonator S can be used to enhance the signal transmission in a specific frequency range, and the parallel arm resonator P can be used to suppress the signal transmission in a specific frequency range. By arranging the plurality of series arm resonators S and the plurality of parallel arm resonators P, the functions of filtering signals, stabilizing frequencies, etc. can be achieved, thereby improving the performance of the surface acoustic wave filter. In this embodiment, since the plurality of series arm resonators S has the first group of resonators, and the plurality of parallel arm resonators P has the second group of resonators, the resonators in the plurality of series arm resonators S have different resonant frequencies from the resonators in the plurality of parallel arm resonators P, so that the rectangularity can be improved and the passband fluctuation can be reduced. In combination with the above, the spurious modes of the first group of resonators and the spurious modes of the second group of resonators can be located outside the passband, so that the spurious modes generated by the series arm resonator S and the parallel arm resonator P do not affect the passband of the surface acoustic wave filter, and the performance of the surface acoustic wave filter is further improved. It should be noted that the plurality of series arm resonators S in the present application is not limited to including the first group of resonators, but can also be provided with other resonators 100 having resonant frequencies different from those of the first group of resonators and the second group of resonators, and / or other first gap regions d1 having lengths along the first direction A different from those of the first group of resonators and the second group of resonators. Meanwhile, the plurality of parallel arm resonators P in the present application is not limited to including the second group of resonators, but can also be provided with other resonators having resonant frequencies different from those of the first group of resonators and the second group of resonators, and / or other first gap regions d1 having lengths along the first direction A different from those of the first group of resonators and the second group of resonators. In the present application, the specific functional requirements of the surface acoustic wave filter can be set without limitation.

[0094] In combination with FIGS. 2-11, please refer to FIGS. 12-14, the present application further provides a surface acoustic wave filter, which includes an input terminal a, an output terminal b, and a plurality of resonators 100 connected between the input terminal a and the output terminal b. The structure of the resonator 100 can refer to the content of the previous embodiment, which will not be repeated here.

[0095] In the embodiment, the plurality of resonators 100 includes a plurality of series arm resonators S and a plurality of parallel arm resonators P, a length of the first gap region d1 of the plurality of series arm resonators S along the first direction A is different from a length of the first gap region d1 of the plurality of parallel arm resonators P along the first direction A.

[0096] In the surface acoustic wave filter of the embodiment, by at least arranging the plurality of series arm resonators S and the plurality of parallel arm resonators P, the functions of filtering the signal and stabilizing the frequency can be realized, so as to improve the performance of the surface acoustic wave filter. The length of the first gap region d1 of the series arm resonator S along the first direction A is arranged to be different from the length of the first gap region d1 of the parallel arm resonator P along the first direction A, so as to respectively adjust the length of the first gap region d1 of the series arm resonator S along the first direction A and the length of the first gap region d1 of the parallel arm resonator P along the first direction A, and then respectively adjust the positions of the spurious modes generated by the non-crossing region R2 of the series arm resonator S and the non-crossing region R2 of the parallel arm resonator P, so that the spurious modes generated by the series arm resonator S and the parallel arm resonator P are located outside the passband, thereby avoiding the spurious modes generated by the non-crossing region R2 of the plurality of resonators 100 from affecting the passband, so as to optimize the performance of the surface acoustic wave filter.

[0097] For example, the resonant frequency of the series arm resonator S is located within the passband of the surface acoustic wave filter, the anti-resonant frequency of the parallel arm resonator P is located within the passband of the surface acoustic wave filter, the spurious mode of the series arm resonator S is located on the high frequency side outside the passband of the surface acoustic wave filter, and the spurious mode of the parallel arm resonator P is located on the low frequency side outside the passband of the surface acoustic wave filter. It should be noted that the resonant frequency of the series arm resonator S is greater than the resonant frequency of the parallel arm resonator P, the anti-resonant frequency of the series arm resonator S is located on the high frequency side outside the passband, and the resonant frequency of the parallel arm resonator P is located on the low frequency side outside the passband. In this example, the length of the first gap region d1 of the series arm resonator S along the first direction A is arranged to be greater than the length of the first gap region d1 of the parallel arm resonator P along the first direction A, so that the spurious mode of the series arm resonator S is located on the high frequency side outside the passband, and the spurious mode of the parallel arm resonator P is located on the low frequency side outside the passband, thereby avoiding the spurious modes generated by the non-crossing region R2 of the series arm resonator S and the parallel arm resonator P from affecting the passband, so as to optimize the performance of the surface acoustic wave filter.

[0098] In some embodiments, the length of the first gap region dl of the plurality of shunt arm resonators P along the first direction A is 0.1λ-0.5λ, and the length of the first gap region dl of the plurality of series arm resonators S along the first direction A is 0.5λ-4.6λ. The length of the first gap region dl of the series arm resonators S along the first direction A is greater than the length of the first gap region dl of the shunt arm resonators P along the first direction A, which can cause the spurious mode of the series arm resonators S to be on the high frequency side, and the spurious mode of the shunt arm resonators P to be on the low frequency side. According to reasonable settings, the spurious mode of the series arm resonators S can be on the high frequency side outside the passband, and the spurious mode of the shunt arm resonators P can be on the low frequency side inside the passband, so as to meet the basic requirements of the length of the first gap region dl along the first direction A, avoid the spurious mode affecting the passband of the surface acoustic wave filter, and improve the performance of the surface acoustic wave filter. Specifically, the resonant frequency of the series arm resonators S can be inside the passband of the surface acoustic wave filter, and the anti-resonant frequency of the shunt arm resonators P can be inside the passband of the surface acoustic wave filter, so as to move the spurious mode outside the passband by adjusting the length of the first gap region dl along the first direction A.

[0099] Exemplarily, as shown in FIGS. 13 and 14, the plurality of resonators 100 further comprises at least one first shunt resonator SP and / or at least one second shunt resonator PS, the at least one first shunt resonator SP is connected to at least one of the plurality of series arm resonators S, and the at least one second shunt resonator PS is connected to at least one of the plurality of shunt arm resonators P. The first shunt resonator SP and the second shunt resonator PS can enhance the selectivity of the surface acoustic wave filter, so that the surface acoustic wave filter can more effectively filter out or suppress signals in a specific frequency range.

[0100] As shown in FIG. 13, exemplarily, there can be only one first shunt resonator SP, which is connected to one of the plurality of series arm resonators S. As shown in FIG. 14, exemplarily, there can be only one second shunt resonator PS, which is connected to one of the plurality of shunt arm resonators P.

[0101] In another example, there can be multiple first shunt resonators SP, which are connected to part of the plurality of series arm resonators S, and there can be multiple second shunt resonators PS, which are connected to part of the plurality of shunt arm resonators P.

[0102] In another example, there can be multiple first shunt resonators SP, and the plurality of first shunt resonators SP and the plurality of series arm resonators S are in one-to-one correspondence, each first shunt resonator SP being connected to one series arm resonator S. There can be multiple second shunt resonators PS, and the plurality of second shunt resonators PS and the plurality of shunt arm resonators P are in one-to-one correspondence, each second shunt resonator PS being connected to one shunt arm resonator P.

[0103] In some embodiments, the first parallel resonator SP and / or the second parallel resonator PS can have a resonant frequency within the passband or an anti-resonant frequency within the passband, and can belong to the first group of resonators or the second group of resonators, which is not limited in the present application.

[0104] In some embodiments, the first parallel resonator SP has a resonant frequency and an anti-resonant frequency both outside the passband of the surface acoustic wave filter, and can belong to the third group of resonators; the second parallel resonator PS has a resonant frequency and an anti-resonant frequency both outside the passband of the surface acoustic wave filter, and can belong to the third group of resonators. In this way, the spurious mode generated by the non-crossing area R2 is located outside the passband, and does not affect the passband performance of the surface acoustic wave filter. Moreover, the first parallel resonator SP and the second parallel resonator PS can enhance the suppression ability of the surface acoustic wave filter to the signal outside the passband, and improve the resistance to the interference outside the passband, thereby enhancing the selectivity of the surface acoustic wave filter.

[0105] For example, the first parallel resonator SP has a resonant frequency and an anti-resonant frequency both on the high frequency side of the passband; the second parallel resonator PS has a resonant frequency and an anti-resonant frequency both on the low frequency side of the passband.

[0106] The structures of the series arm resonator S, the parallel arm resonator P, the first parallel resonator SP and the second parallel resonator PS provided in the embodiments of the present application can refer to the structure of the resonator 100 in the foregoing embodiments, and will not be described herein.

[0107] In combination with FIGS. 2-11, please refer to FIGS. 12-14, the embodiments of the present application further provide a surface acoustic wave filter, which comprises an input terminal a, an output terminal b and a plurality of resonators 100 connected between the input terminal a and the output terminal b. The structure of the resonator 100 can refer to the content of the foregoing embodiments, which will not be described herein.

[0108] In the embodiments, the plurality of resonators 100 at least comprises a first group of resonators and a second group of resonators, the resonant frequency of the first group of resonators is within the passband, and the anti-resonant frequency of the second group of resonators is within the passband, the length of the first gap area d1 of the first group of resonators along the first direction A is greater than the length of the first gap area d1 of the second group of resonators along the first direction A; wherein the first direction A is the direction of the relative arrangement of the two bus bars 11.

[0109] In the embodiments, the length of the first gap area d1 of the first group of resonators along the first direction A is set to be greater than the length of the first gap area d1 of the second group of resonators along the first direction A, which can reduce the influence of the spurious mode of the first group of resonators and / or the second group of resonators on the passband performance of the surface acoustic wave filter, and improve the insertion loss of the surface acoustic wave filter.

[0110] In some embodiments, the length of the first gap region d1 of the first group of resonators along the first direction A is 0.1λ-0.5λ, and the length of the first gap region d1 of the first group of resonators along the first direction A is 0.5λ-4.6λ, where λ represents the pitch of adjacent electrode fingers connected to the same bus bar. By this arrangement, the influence of the spurious mode on the passband performance of the surface acoustic wave filter can be further reduced, thereby further improving the insertion loss of the surface acoustic wave filter.

[0111] The present application also provides a radio frequency front-end module comprising the surface acoustic wave filter as described in the above embodiments. By arranging at least the first group of resonators and the second group of resonators, the influence of the spurious mode on the passband can be reduced, so as to optimize the performance of the surface acoustic wave filter, and further improve the working performance of the radio frequency front-end module. In some embodiments, the radio frequency front-end module comprises at least one surface acoustic wave filter. That is, the radio frequency front-end module can comprise only one surface acoustic wave filter, or two or more surface acoustic wave filters, so as to further improve the working performance of the radio frequency front-end module. In some embodiments, the radio frequency front-end module can further comprise other devices, such as radio frequency switches, noise amplifiers, power amplifiers, etc. The specific connection mode is not limited. In some embodiments, the radio frequency front-end module can be applied to electronic devices, including but not limited to LED panels, tablets, notebooks, computers, navigation devices, mobile phones, and electronic watches, etc. electronic devices or components with PCBs.

[0112] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation based on the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A surface acoustic wave filter, comprising: An input terminal, an output terminal, and a plurality of resonators connected between the input terminal and the output terminal; The resonator comprises an interdigital transducer, the interdigital transducer comprises two bus bars arranged in parallel and spaced apart, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are respectively connected with one of the two bus bars, and the plurality of electrode fingers connected with different bus bars are arranged alternately and spaced apart along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, and the non-intersection region comprises a first gap region; wherein the intersection region is a region where the plurality of electrode fingers overlap with each other. The plurality of resonators at least comprises a first group of resonators and a second group of resonators, the resonant frequency of the first group of resonators is different from the resonant frequency of the second group of resonators, and the length of the first gap region of the first group of resonators in a first direction is different from the length of the first gap region of the second group of resonators in the first direction; wherein the first direction is the direction of the relative arrangement of the two bus bars.

2. The surface acoustic wave filter according to claim 1, wherein, The resonant frequency or anti-resonant frequency of the resonators of at least one of the first group of resonators and the second group of resonators is within the passband of the surface acoustic wave filter.

3. The surface acoustic wave filter of claim 2, wherein, The resonant frequency of the first group of resonators and the resonant frequency of the second group of resonators are both within the passband, and the spurious mode of the first group of resonators and the spurious mode of the second group of resonators are both on the high frequency side of the passband of the surface acoustic wave filter.

4. The surface acoustic wave filter of claim 2, wherein, The anti-resonant frequency of the first group of resonators and the anti-resonant frequency of the second group of resonators are both within the passband, and the spurious mode of the first group of resonators and the spurious mode of the second group of resonators are both on the low frequency side of the passband of the surface acoustic wave filter.

5. The surface acoustic wave filter of claim 1, wherein, The resonant frequency of the first group of resonators is greater than the resonant frequency of the second group of resonators, and the length of the first gap region of the first group of resonators in the first direction is greater than or less than the length of the first gap region of the second group of resonators in the first direction.

6. The surface acoustic wave filter of claim 1, wherein, The resonant frequency of the first group of resonators is within the passband of the surface acoustic wave filter, the anti-resonant frequency of the second group of resonators is within the passband of the surface acoustic wave filter, and the length of the first gap region of the first group of resonators in the first direction is greater than the length of the first gap region of the second group of resonators in the first direction.

7. The surface acoustic wave filter of claim 6, wherein, The spurious mode of the first group of resonators is on the high frequency side of the passband of the surface acoustic wave filter, and the spurious mode of the second group of resonators is on the low frequency side of the passband of the surface acoustic wave filter.

8. The surface acoustic wave filter of claim 1, wherein, The length of the first gap region in the first direction is 0.1λ-4.6λ; Wherein, λ is the period of the resonator.

9. The surface acoustic wave filter of claim 1, wherein, The size of the intersection region in the first direction is less than 20λ; Wherein, λ represents the pitch of adjacent electrode fingers connected with the same bus bar.

10. The surface acoustic wave filter of claim 1, wherein, The non-crossing area further comprises a second gap area, the first gap area and the second gap area are located in the same crossing area, and the first gap area is closer to the bus bar than the second gap area.

11. The surface acoustic wave filter of claim 10, wherein, The electrode finger comprises a connecting portion, a main body portion and an intermediate portion, the connecting portion and the main body portion both extend in the first direction, the intermediate portion extends in the arrangement direction of the electrode finger, the connecting portion and the main body portion are connected to the intermediate portion in the first direction, and one end of the connecting portion away from the intermediate portion is connected to one bus bar, and one end of the main body portion away from the intermediate portion is spaced apart from another bus bar, and the first gap area is formed between the intermediate portion and the one bus bar.

12. The surface acoustic wave filter of claim 11, wherein, The interdigital transducer further comprises a first dummy finger, the first dummy finger is connected to the intermediate portion and extends towards the crossing area in the first direction, and the first dummy finger and the main body portion are spaced apart along the length direction of the bus bar.

13. The surface acoustic wave filter of claim 11, wherein, The interdigital transducer further comprises a second dummy finger, one end of the second dummy finger is connected to the bus bar, and the other end of the second dummy finger is opposite to and spaced apart from the intermediate portion adjacent to the bus bar, and the first gap area is formed between the second dummy finger and the intermediate portion adjacent to the bus bar.

14. The surface acoustic wave filter of claim 10, wherein, The interdigital transducer further comprises two conductive portions, the two conductive portions extend along the length direction of the bus bar, the two conductive portions are respectively connected to a plurality of electrode fingers connecting the two bus bars, the two conductive portions are respectively arranged in the two non-crossing areas, each conductive portion is spaced apart from the bus bar and the crossing area, and the first gap area is formed between the conductive portion and the corresponding bus bar.

15. The surface acoustic wave filter of claim 14, wherein, The conductive portion is a continuous conductive strip, or the conductive portion comprises a plurality of conductive segments, and the plurality of conductive segments are discontinuously arranged in the length direction of the bus bar.

16. The surface acoustic wave filter of claim 1, wherein, The crossing area comprises a middle area and edge areas located on both sides of the middle area in the first direction, and the edge areas are provided with mass additional structures so that the sound speed of the edge areas is less than the sound speed of the middle area.

17. The surface acoustic wave filter of claim 1, wherein, The plurality of resonators comprises a plurality of series arm resonators and a plurality of parallel arm resonators, the plurality of series arm resonators are connected in series between the input terminal and the output terminal, one end of the parallel arm resonator is connected to the series arm resonator, and the other end of the parallel arm resonator is connected to a ground terminal, the resonant frequency of the series arm resonator is greater than the resonant frequency of the parallel arm resonator, the first group of resonators comprises at least one series arm resonator, the second group of resonators comprises at least one parallel arm resonator, and the length of the first gap area of the first group of resonators in the first direction is greater than the length of the first gap area of the second group of resonators in the first direction.

18. A surface acoustic wave filter, wherein, The input terminal, the output terminal and the plurality of resonators connected between the input terminal and the output terminal are provided. ​ The resonator comprises an interdigital transducer, the interdigital transducer comprises: two bus bars arranged in parallel and at intervals, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are respectively connected with one of the two bus bars, and the plurality of electrode fingers connected with different bus bars are arranged at intervals and alternately along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, and the non-intersection region is provided with a first gap region; wherein the intersection region is an area in which the plurality of electrode fingers overlap with each other. The plurality of resonators comprise a plurality of series arm resonators and a plurality of parallel arm resonators, the length of the first gap region of the plurality of series arm resonators in a first direction is different from the length of the first gap region of the plurality of parallel arm resonators in the first direction; wherein the first direction is the direction in which the two bus bars are arranged oppositely.

19. The surface acoustic wave filter of claim 18, wherein, The length of the first gap region of the plurality of series arm resonators in the first direction is greater than the length of the first gap region of the plurality of parallel arm resonators in the first direction.

20. The surface acoustic wave filter of claim 19, wherein, The length of the first gap region of the plurality of parallel arm resonators in the first direction is 0.1λ-0.5λ, and the length of the first gap region of the plurality of series arm resonators in the first direction is 0.5λ-4.6λ.

21. The surface acoustic wave filter of claim 18, wherein, The plurality of resonators further comprise at least one first parallel resonator and / or at least one second parallel resonator, at least one of the first parallel resonators is connected in parallel with at least one of the plurality of series arm resonators, and at least one of the second parallel resonators is connected in parallel with at least one of the plurality of parallel arm resonators.

22. The surface acoustic wave filter of claim 21, wherein, The resonant frequency and the anti-resonant frequency of the first parallel resonator are both located outside the passband of the surface acoustic wave filter; and the resonant frequency and the anti-resonant frequency of the second parallel resonator are both located outside the passband of the surface acoustic wave filter.

23. The surface acoustic wave filter of claim 18, wherein, The length of the first gap region in the first direction is 0.1λ-4.6λ; Wherein, λ represents the pitch of adjacent electrode fingers connected with the same bus bar.

24. A surface acoustic wave filter, wherein, Comprise: an input terminal, an output terminal, and a plurality of resonators connected between the input terminal and the output terminal; The resonator comprises an interdigital transducer, the interdigital transducer comprises: two bus bars arranged in parallel and at intervals, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are respectively connected with one of the two bus bars, and the plurality of electrode fingers connected with different bus bars are arranged at intervals and alternately along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, and the non-intersection region comprises a first gap region; wherein the intersection region is an area in which the plurality of electrode fingers overlap with each other. The resonators include at least a first group of resonators and a second group of resonators, the resonant frequency of the first group of resonators is within a passband, the anti-resonant frequency of the second group of resonators is within the passband, the length of the first gap region of the first group of resonators along a first direction is greater than the length of the first gap region of the second group of resonators along the first direction; wherein the first direction is the direction in which the two bus bars are oppositely arranged.

25. The surface acoustic wave filter of claim 24, wherein, The length of the first gap region of the second group of resonators along the first direction is 0.1λ-0.5λ, and the length of the first gap region of the first group of resonators along the first direction is 0.5λ-4.6λ; Wherein λ represents the pitch of adjacent electrode fingers connected to the same bus bar.

26. The surface acoustic wave filter of claim 24, wherein, The length of the first gap region along the first direction is 0.1λ-4.6λ; and / or, the size of the intersection region in the first direction is less than 20λ; Wherein λ represents the pitch of adjacent electrode fingers connected to the same bus bar.

27. A radio frequency front end module, comprising: A surface acoustic wave filter includes an input terminal, an output terminal, and a plurality of resonators connected between the input terminal and the output terminal. The resonators include interdigital transducers, the interdigital transducers include two bus bars arranged in parallel and spaced apart, and a plurality of electrode fingers located between the two bus bars, the plurality of electrode fingers are respectively connected to one of the two bus bars, and the plurality of electrode fingers connected to different bus bars are spaced apart and alternately arranged along the length direction of the bus bar; an intersection region is formed between the two bus bars, and a non-intersection region is located between the intersection region and the two bus bars, the non-intersection region includes a first gap region; wherein the intersection region is a region in which the plurality of electrode fingers overlap each other. The resonators include at least a first group of resonators and a second group of resonators, the resonant frequency of the first group of resonators is different from the resonant frequency of the second group of resonators, and the length of the first gap region of the first group of resonators along a first direction is different from the length of the first gap region of the second group of resonators along the first direction; wherein the first direction is the direction in which the two bus bars are oppositely arranged.

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