Filter circuit topological structure, radio frequency module and electronic equipment

Abstract

The invention discloses a filter circuit topological structure, a radio frequency module and electronic equipment, and relates to the field of filters, and the filter circuit topological structure comprises an input end and an output end; the N + 1 series resonator units are sequentially connected between the input end and the output end, and the first series resonator unit to the N + 1 series resonator unit are sequentially arranged on a series path from the input end to the output end; an ith parallel node is arranged between the ith series resonator unit and the (i + 1) th series resonator unit; the N parallel resonator units are sequentially a first parallel resonator unit to an Nth parallel resonator unit; the ith parallel node is connected with the grounding end through the ith parallel resonator unit, N is a positive integer, and i is a positive integer not greater than N; at least one of the first to Nth parallel resonator units is a first resonator unit including a plurality of surface acoustic wave resonators connected in parallel between a corresponding parallel node and a ground terminal.

Description

Technical Field

[0001] The present application relates to the technical field of filters, and in particular, to a filter circuit topology, a radio frequency module, and an electronic device. Background Art

[0002] A surface acoustic wave resonator (Surface Acoustic Wave, abbreviated as SAW) is a device widely used in the radio frequency field, which combines low insertion loss and good suppression performance, and has a small volume at the same time. It mainly uses the piezoelectric effect to convert electrical energy and mechanical energy into each other, and can be used in combination to achieve a gating characteristic for signal transmission.

[0003] Multiple surface acoustic wave resonators can be interconnected to form a filter. As one of the key components of a radio frequency module, a filter based on a surface acoustic wave resonator needs to have excellent linearity to avoid generating non-linear signals such as harmonics and intermodulation distortion, so as to avoid affecting the signals of the transceiver link. At present, there are strong harmonics in conventional filters, which will affect the performance of the filter. Summary of the Invention

[0004] In view of the above problems, the present application provides a filter circuit topology, a radio frequency module, and an electronic device, which can at least achieve the purpose of reducing the second harmonic in the filter. The specific solutions are as follows:

[0005] A first aspect of the present application provides a filter circuit topology, including:

[0006] An input end and an output end;

[0007] N + 1 series resonator units connected in sequence between the input end and the input end. On the series path from the input end to the output end, the N + 1 series resonator units are the 1st series resonator unit to the (N + 1)th series resonator unit in sequence; there is a 1st parallel node between the ith series resonator unit and the (i + 1)th series resonator unit;

[0008] N parallel resonator units, which are the 1st parallel resonator unit to the Nth parallel resonator unit in sequence; the ith parallel node is connected to the ground terminal through the ith parallel resonator unit, N is a positive integer, and i is a positive integer not greater than N;

[0009] Wherein, at least one of the 1st parallel resonator unit to the Nth parallel resonator unit is a first resonator unit, and the first resonator unit includes a plurality of surface acoustic wave resonators connected in parallel between the corresponding parallel node and the ground terminal.

[0010] Optionally, in the above filter circuit topology, the surface acoustic wave resonator includes a piezoelectric substrate and interdigital transducers located on the piezoelectric substrate;

[0011] In the first resonator unit, surface acoustic wave resonators share the same piezoelectric substrate, and interdigital transducers are connected in parallel on the same side surface of the piezoelectric substrate.

[0012] Optionally, in the above filter circuit topology, the interdigital transducer includes a first interdigital electrode and a second interdigital electrode; the first interdigital electrode includes a first bus bar and a plurality of first finger bars led out on the same side of the first bus bar; the second interdigital electrode includes: a second bus bar and a plurality of second finger bars led out on the same side of the bus bar; the first finger bars and the second finger bars are alternately arranged in a first direction, the first bus bar and the second bus bar are oppositely arranged in a second direction, and the first finger bars and the second finger bars are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and both parallel to the plane where the piezoelectric substrate is located;

[0013] In the same first resonator unit, the interdigital transducers of each surface acoustic wave resonator are arranged in sequence along the first direction; the surface acoustic wave resonators share the same first bus bar, or the first bus bars of the surface acoustic wave resonators are all connected to the same first connecting member; the surface acoustic wave resonators share the same second bus bar, or the second bus bars of the surface acoustic wave resonators are connected to the same second connecting member.

[0014] Optionally, in the above filter circuit topology, in the same first resonator unit, the interdigital transducers of each surface acoustic wave resonator are arranged in sequence along the first direction, and the graphic structures of all interdigital transducers are axisymmetric about the axis of symmetry parallel to the second direction; the first direction and the second direction are perpendicular to each other and both parallel to the plane where the piezoelectric substrate is located.

[0015] Optionally, in the above filter circuit topology, at least one of the first series resonator unit to the N+1 series resonator unit is a second resonator unit, and the second resonator unit includes a plurality of surface acoustic wave resonators connected in series in series path.

[0016] Optionally, in the above filter circuit topology, the surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate;

[0017] In the second resonator unit, surface acoustic wave resonators share the same piezoelectric substrate, and interdigital transducers are connected in series on the same side surface of the piezoelectric substrate.

[0018] Optionally, in the above filter circuit topology, the interdigital transducer includes a first interdigital electrode and a second interdigital electrode; the first interdigital electrode includes a first bus bar and a plurality of first finger bars led out on the same side of the first bus bar; the second interdigital electrode includes: a second bus bar and a plurality of second finger bars led out on the same side of the bus bar; the first finger bars and the second finger bars are alternately arranged in a first direction, the first bus bar and the second bus bar are oppositely arranged in a second direction, and the first finger bars and the second finger bars are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and both parallel to the plane where the piezoelectric substrate is located;

[0019] In the same second resonator unit, the interdigital transducers of the surface acoustic wave resonators are arranged in sequence along the second direction; for two adjacent interdigital transducers in the second direction, the adjacent bus bars thereof are connected.

[0020] Optionally, in the above filter circuit topology, in the same second resonator unit, for two adjacent interdigital transducers in the second direction, the adjacent bus bars thereof are the same bus bar, or the adjacent bus bars thereof are connected by a third connecting member.

[0021] Optionally, in the above filter circuit topology, at least the A-th series resonator unit and the B-th series resonator unit are second resonator units; both A and B are positive integers not greater than N + 1, and A is less than B;

[0022] The A-th series resonator unit has a surface acoustic wave resonators connected in series, and the B-th series resonator unit has b surface acoustic wave resonators connected in series; both a and b are positive integers greater than 1, and a is less than b.

[0023] Optionally, in the above filter circuit topology, the surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate;

[0024] The interdigital transducer includes a first interdigital electrode and a second interdigital electrode; the first interdigital electrode includes a first bus bar and a plurality of first finger bars led out on the same side of the first bus bar; the second interdigital electrode includes: a second bus bar and a plurality of second finger bars led out on the same side of the bus bar; the first finger bars and the second finger bars are alternately arranged in a first direction, the first bus bar and the second bus bar are oppositely arranged in a second direction, and the first finger bars and the second finger bars are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and both parallel to the plane where the piezoelectric substrate is located;

[0025] Wherein, the first bus bar and / or the second bus bar includes a hollowed-out area.

[0026] Optionally, in the above filter circuit topology, at least the Cth parallel resonator unit and the Dth parallel resonator unit are the first resonator units; both C and D are positive integers not greater than N, and C is less than D.

[0027] The Cth parallel resonator unit has c surface acoustic wave resonators connected in parallel, and the Dth parallel resonator unit has d surface acoustic wave resonators connected in parallel; both c and d are positive integers greater than 1, and c is less than d.

[0028] The second aspect of the present application provides a radio frequency module, including the above filter circuit topology.

[0029] The third aspect of the present application provides an electronic device, including the above radio frequency module.

[0030] By means of the above technical solution, in the technical solution of the present application, at least one parallel resonator unit is set as the first resonator unit. The first resonator unit includes a plurality of surface acoustic wave resonators connected in parallel. The first resonator unit can reduce the second harmonic in the parallel resonator unit through the plurality of surface acoustic wave resonators connected in parallel, thereby reducing the influence of the second harmonic on the filter performance and improving the filter performance. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0032] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limited conditions that can be implemented by the present application. Therefore, they do not have technical essential significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size should still fall within the scope covered by the technical content disclosed in the present application without affecting the effects that the present application can produce and the purposes that can be achieved.

[0033] Figure 1 It is an equivalent circuit diagram of a filter circuit topology;

[0034] Figure 2 It is an equivalent circuit diagram of a filter circuit topology provided by an embodiment of the present application;

[0035] Figure 3 It is an equivalent circuit diagram of another filter circuit topology provided by an embodiment of the present application;

[0036] Figure 4 The equivalent circuit diagram of another filter circuit topology provided by the embodiment of the present application;

[0037] Figure 5 The equivalent circuit diagram of another filter circuit topology provided by the embodiment of the present application;

[0038] Figure 6 The top view of a surface acoustic wave resonator;

[0039] Figure 7 is Figure 6 The sectional view of the surface acoustic wave resonator shown along the P-P' direction;

[0040] Figure 8 The top view of a first resonator unit provided by the embodiment of the present application;

[0041] Figure 9 is Figure 8 The sectional view of the first resonator unit shown in the Q-Q' direction;

[0042] Figure 10 The sectional view of a first resonator unit provided by the embodiment of the present application;

[0043] Figure 11 The sectional view of another first resonator unit provided by the embodiment of the present application;

[0044] Figure 12 The sectional view of another first resonator unit provided by the embodiment of the present application;

[0045] Figure 13 The top view of another first resonator provided by the embodiment of the present application;

[0046] Figure 14 The top view of another first resonator provided by the embodiment of the present application;

[0047] Figure 15 The top view of a second resonator provided by the embodiment of the present application;

[0048] Figure 16 The top view of another second resonator provided by the embodiment of the present application;

[0049] Figure 17 The top view of another second resonator provided by the embodiment of the present application;

[0050] Figure 18 The top view of another second resonator provided by the embodiment of the present application;

[0051] Figure 19 The top view of another second resonator provided by the embodiment of the present application;

[0052] Figure 20 It is a test curve graph of the second harmonic of two surface acoustic wave resonators connected in parallel.

[0053] Reference numerals:

[0054] 10 - Surface acoustic wave resonator; 11 - First resonator unit; 12 - Second resonator unit; 13 - Third resonator unit; 14 - Fourth resonator unit; 15 - Piezoelectric substrate; 151 - Piezoelectric layer; 152 - Substrate; 153 - High acoustic velocity layer; 16 - Interdigital transducer; 171 - First interdigital electrode; 172 - Second interdigital electrode; 181 - First bus bar; 182 - Second bus bar; 191 - First finger bar; 192 - Second finger bar; 201 - First connecting member; 202 - Second connecting member; 203 - Third connecting member; 21 - Temperature compensation layer; 22 - Hollowed-out area; GND - Ground terminal; X - First direction; Y - Second direction. Detailed implementation manners

[0055] Next, the embodiments in the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Those of ordinary skill in the art can know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0056] As described in the background art, there are strong harmonics in conventional filters, which will affect the performance of the filters. Among them, the filter can be a duplexer or other types of filters, and the specific type of the filter in the embodiments of the present application is not limited.

[0057] Refer to Figure 1 , Figure 1 which is an equivalent circuit diagram of a filter circuit topology. The shown filter circuit topology includes:

[0058] Input terminal In and output terminal Out;

[0059] N + 1 series resonator units connected in sequence between the input terminal In and the output terminal Out; on the series path from the input terminal In to the output terminal Out, these N + 1 series resonator units are the 1st series resonator unit s 1 to the (N + 1)th series resonator unit s N+1 ; the 1st series resonator unit s 1 to the (N + 1)th series resonator unit s N+1 are all a surface acoustic wave resonator 10; there is a (i)th parallel node D i between the (i)th series resonator unit s i+1 and the (i + 1)th series resonator unit s i ;

[0060] N parallel resonator units, which are successively the 1st parallel resonator unit p 1 to the Nth parallel resonator unit p N ; the 1st parallel resonator unit p 1 to the Nth parallel resonator unit p N are all a surface acoustic wave resonator 10;

[0061] wherein, the ith parallel node D i is grounded through the ith parallel resonator unit p i , and i is a positive integer not greater than N.

[0062] Figure 1 Taking N = 4 as an example for illustration, the 1st series resonator unit s 1 to the 5th series resonator unit s 5 are successively connected in series between the input terminal In and the output terminal Out, and correspondingly have the 1st parallel node D 1 to the 4th parallel node D 4 . The 1st parallel resonator unit p 1 is connected between the 1st parallel node D 1 and the ground terminal GND; the 2nd parallel resonator unit p 2 is connected between the 2nd parallel node D 2 and the ground terminal GND; the 3rd parallel resonator unit p 3 is connected between the 3rd parallel node D 3 and the ground terminal GND; the 4th parallel resonator unit p 4 is connected between the 4th parallel node D 4 and the ground terminal GND.

[0063] In Figure 1 the shown manner, since each parallel resonator unit is formed by a surface acoustic wave resonator 10, there is a strong second harmonic in the parallel resonator unit, which will affect the stability and reliability of the filter.

[0064] In addition, since each series resonator unit is formed by a surface acoustic wave resonator 10, there is a large power density in the series resonator unit, resulting in a strong non-linear response of the filter.

[0065] To solve the above problems, an embodiment of the present application provides a filter circuit topology, including:

[0066] an input terminal and an output terminal;

[0067] N + 1 series resonator units connected in series between the input terminals in sequence. On the series path from the input terminal to the output terminal, the N + 1 series resonator units are the 1st series resonator unit to the (N + 1)th series resonator unit in sequence; there is an ith parallel node between the ith series resonator unit and the (i + 1)th series resonator unit;

[0068] N parallel resonator units, which are the 1st parallel resonator unit to the Nth parallel resonator unit in sequence; the ith parallel node is connected to the ground terminal through the ith parallel resonator unit, where N is a positive integer and i is a positive integer not greater than N;

[0069] In the technical solution of this application, at least one parallel resonator unit is set as the first resonator unit. The first resonator unit includes a plurality of parallel surface acoustic wave resonators. The first resonator unit can reduce the second harmonic in the parallel resonator unit through the plurality of parallel surface acoustic wave resonators, thereby reducing the influence of the second harmonic on the filter performance and improving the filter performance.

[0070] Optionally, in the embodiment of this application, at least one of the N + 1 series resonator units can also be set as the second resonator unit. The second resonator unit can reduce the power density of the series resonator unit through a plurality of sequentially connected surface acoustic wave resonators, thereby reducing the non - linear response of the filter.

[0071] To make the above - mentioned objects, features, and advantages of this application more obvious and understandable, the following further details this application in conjunction with the drawings and specific embodiments.

[0072] Refer to Figure 2 , Figure 2 which is the equivalent circuit diagram of a filter circuit topology provided by the embodiment of this application. The shown filter circuit topology includes:

[0073] An input terminal In and an output terminal Out;

[0074] N + 1 series resonator units connected in series between the input terminal In and the output terminal Out. On the series path from the input terminal In to the output terminal Out, the N + 1 series resonator units are the 1st series resonator unit s 1 to the (N + 1)th series resonator unit s N+1 ; there is an ith parallel node D i between the ith series resonator unit s i and the (i + 1)th series resonator unit s i+1 . There are N parallel nodes, which are the 1st parallel node D 1 to the Nth parallel node D N in sequence;

[0075] N parallel resonator units, successively being the 1st parallel resonator unit p 1 to the Nth parallel resonator unit p N ; the ith parallel node D i is connected to the ground terminal GND through the ith parallel resonator unit p i , that is, the ith parallel node D i is grounded through the ith parallel resonator unit p i , N is a positive integer, and i is a positive integer not greater than N;

[0076] Among them, at least one of the 1st parallel resonator unit p 1 to the Nth parallel resonator unit p N is the first resonator unit 11, and the first resonator unit 11 includes a plurality of surface acoustic wave resonators 10 connected in parallel between the corresponding parallel node and the ground terminal GND.

[0077] Optionally, both the parallel resonator unit and the series resonator unit have independent piezoelectric substrates.

[0078] In Figure 2 the illustrated manner, taking N = 4 as an example for illustration, the filter circuit topology has the 1st series resonator unit s 1 to the 5th series resonator unit s 5 ; the 1st parallel resonator unit p 1 to the 4th parallel resonator unit p 4 ; the 1st parallel node D 1 to the 4th parallel node D 4 . It is easy to know that the embodiment of the present application is not limited to N = 4, and N can be set to any positive integer according to requirements, and no limitation is imposed on the specific value of N. For example, N can also be equal to 5, or 7, or 8, or 10, etc.

[0079] In Figure 2 the illustrated manner, taking the 1st parallel resonator unit p 1 as the first resonator unit 11 and including two surface acoustic wave resonators 10 connected in parallel between the 1st parallel node D 1 and the ground terminal GND as an example for illustration, the two surface acoustic wave resonators 10 are respectively represented by p 1-1 , p 1-2 . It is easy to know that any one of the 1st parallel resonator unit p 1 to the Nth parallel resonator unit p N is the first resonator unit 11 or any multiple of them are the first resonator unit 11, not limited to Figure 2 only the 1st parallel resonator unit p 1is the mode of the first resonator unit 11; the number of parallel SAW resonators 10 in the first resonator unit 11 is not limited to 2. In the embodiments of the present application, the number of parallel SAW resonators 10 in the first resonator unit 11 is not limited. For example, the number of parallel SAW resonators 10 in the first resonator unit 11 can be 3, or 4, or 5, or 8, etc.

[0080] In the embodiments of the present application, at least one parallel resonator unit is set as the first resonator unit 11. The first resonator unit 11 includes a plurality of parallel SAW resonators 10. The first resonator unit 11 can reduce the second harmonic in the parallel resonator unit through the plurality of parallel SAW resonators 10, thereby reducing the influence of the second harmonic on the filter performance and improving the filter performance.

[0081] Reference Figure 3 , Figure 3 is the equivalent circuit diagram of another filter circuit topology provided by the embodiments of the present application. On the basis of any implementation manner of the present application, Figure 3 In the shown mode, the 1st series resonator unit s 1 to the N+1th series resonator unit s N+1 at least one of them is the second resonator unit 12. The second resonator unit 12 includes a plurality of SAW resonators 10 connected in series in series paths.

[0082] In Figure 3 In the shown mode, taking the 3rd series resonator unit s 3 as the second resonator unit 12 and including two series-connected SAW resonators 10 as an example for illustration. It is easy to know that any one of the 1st series resonator unit s 1 to the N+1th series resonator unit s N+1 is the second resonator unit 12 or any multiple of them are the second resonator unit 12, not limited to Figure 3 the mode in the shown mode where only the 3rd series resonator unit s 3 is the second resonator unit 12; the number of series-connected SAW resonators 10 in the second resonator unit 12 is not limited to 2. In the embodiments of the present application, the number of series-connected SAW resonators 10 in the second resonator unit 12 is not limited. For example, the number of series-connected SAW resonators 10 in the second resonator unit 12 can be 3, or 4, or 5, or 8, etc.

[0083] In the embodiments of the present application, at least one of the N+1 series resonator units can be set as the second resonator unit 12. The second resonator unit 12 can reduce the power density of the series resonator unit through a plurality of sequentially series-connected SAW resonators 10, thereby reducing the non-linear response of the filter.

[0084] Optionally, at least one of the first parallel resonator unit p 1 to the Nth parallel resonator unit p N is the third resonator unit 13, and the third resonator unit 13 includes a surface acoustic wave resonator 10. In this way, only some of the parallel resonator units need to be formed by a plurality of parallel-connected surface acoustic wave resonators 10 to serve as the first resonator unit 11; some other parallel resonator units can be formed by one surface acoustic wave resonator 10 to serve as the third resonator unit 13. This way can reduce the second harmonic in the parallel resonator unit while simplifying the system structure of the filter circuit topology.

[0085] In other ways, according to the performance requirements of the filter, all the parallel resonator units can also be set as the first resonator unit 11, all including a plurality of parallel-connected surface acoustic wave resonators 10.

[0086] Optionally, at least one of the first series resonator unit s 1 to the (N + 1)th series resonator unit s N+1 is the fourth resonator unit 14, and the fourth resonator unit 14 includes a surface acoustic wave resonator. In this way, only some of the series resonator units need to be formed by a plurality of series-connected surface acoustic wave resonators 10 to serve as the second resonator unit 12; some other series resonator units can be formed by one surface acoustic wave resonator 10 to serve as the fourth resonator unit 14. This way can reduce the power density of the series resonator unit while simplifying the system structure of the filter circuit topology.

[0087] In other ways, according to the performance requirements of the filter, all the series resonator units can also be set as the second resonator unit 12, all including a plurality of series-connected surface acoustic wave resonators 10.

[0088] Reference Figure 4 , Figure 4 is an equivalent circuit diagram of another filter circuit topology provided by the embodiment of the present application. On the basis of the above embodiments, Figure 4 in the shown way, at least the Cth parallel resonator unit p C and the Dth parallel resonator unit p D are the first resonator unit 11; both C and D are positive integers not greater than N, and C is less than D; the Cth parallel resonator unit p C has c parallel-connected surface acoustic wave resonators 10, and the Dth parallel resonator unit p D has d parallel-connected surface acoustic wave resonators 10; both c and d are positive integers greater than 1, and c is less than d. In Figure 4Among them, taking C = 1, D = 3, c = 2, and d = 3 as an example for illustration. The first parallel resonator unit p 1 and the third parallel resonator unit p 3 are both the first resonator units 11. The first parallel resonator unit p 1 has two parallel surface acoustic wave resonators 10, and the two parallel surface acoustic wave resonators 10 are respectively p 1-1 、p 1-2 . The third parallel resonator unit p 3 has three parallel surface acoustic wave resonators 10, and the three parallel surface acoustic wave resonators 10 are respectively p 3-1 、p 3-2 、p 3-3 . In this way, when the filter circuit topology has multiple first resonator units 11, the first resonator unit 11 closer to the output end Out has a larger number of surface acoustic wave resonators 10, which can better improve the output characteristics of the filter.

[0089] For the parallel resonator unit with second harmonics, the closer it is to the output end Out, the greater the influence of the second harmonics of the parallel resonator unit on the output characteristics of the filter. In view of this, in the embodiments of the present application, when the filter circuit topology has multiple first resonator units 11, it is set that the first resonator unit 11 closer to the output end Out has a larger number of parallel surface acoustic wave resonators 10, so that the first resonator unit 11 closer to the output end Out can reduce the second harmonics of the corresponding parallel resonator unit to a greater extent, so as to better improve the output characteristics of the filter.

[0090] In other ways, when multiple parallel resonator units are all the first resonator units 11, it can be set that each first resonator unit 11 has the same number of parallel surface acoustic wave resonators 10, so as to facilitate the preparation of multiple first resonator units 11 based on the same design parameters, so as to simplify the preparation process of the filter.

[0091] In other ways, it can also be set that one of the (2j - 1)-th parallel resonator unit p 2j-1 and the 2j-th parallel resonator unit p 2j is the first resonator unit 11, and the other is the third resonator unit 13, and each first resonator unit 11 has the same number of parallel surface acoustic wave resonators 10, j is a positive integer, and 2j is not greater than N. In this way, among the first parallel resonator unit p 1 to the N-th parallel resonator unit p N , the first resonator unit 11 and the third resonator unit 13 can be arranged alternately periodically. This periodic arrangement method not only facilitates the process preparation of the series resonator unit, but also can better eliminate the second harmonics.

[0092] Reference Figure 5 , Figure 5 is the equivalent circuit diagram of another filter circuit topology provided by the embodiments of the present application. On the basis of the above embodiments, Figure 5 in the shown manner, at least the A-th series resonator unit s A and the B-th series resonator unit s B are the second resonator units 12; both A and B are positive integers not greater than N + 1, and A is less than B; the A-th series resonator unit s A has a series of a surface acoustic wave resonators 10, and the B-th series resonator unit s B has a series of b surface acoustic wave resonators 10; both a and b are positive integers greater than 1, and a is less than b. In Figure 5 , taking A = 3, B = 4, a = 2, and b = 3 as an example for illustration. The 3rd series resonator unit s 3 and the 4th series resonator unit s 4 are both the second resonator units 12. The 3rd series resonator unit s 3 has two series-connected surface acoustic wave resonators 10, and the two parallel-connected surface acoustic wave resonators 10 are respectively s 3-1 , s 3-2 . The 4th series resonator unit s 4 has three series-connected surface acoustic wave resonators 10, and the three series-connected surface acoustic wave resonators 10 are respectively s 4-1 , s 4-2 , s 4-3 . In this manner, when the filter circuit topology has multiple second resonator units 12, the second resonator unit 12 closer to the output end Out has a larger number of surface acoustic wave resonators 10, which can better improve the output characteristics of the filter.

[0093] For the series resonator unit affecting the power module, the closer it is to the output end Out, the greater the influence of the series resonator unit on the power density. In view of this, in the embodiments of the present application, when the filter circuit topology has multiple second resonator units 12, setting the second resonator unit 12 closer to the output end Out to have a larger number of series-connected surface acoustic wave resonators 10 can enable the second resonator unit 12 closer to the output end Out to reduce the power density to a greater extent, so as to better reduce the non-linear response and better improve the output characteristics of the filter.

[0094] In other ways, when multiple series resonator units are all the second resonator units 12, it can be set that each second resonator unit 12 has the same number of parallel-connected surface acoustic wave resonators 10, so as to facilitate the preparation of multiple second resonator units 12 based on the same design parameters and simplify the preparation process of the filter.

[0095] In other ways, the (2t - 1)-th series resonator unit s can also be set 2t-1 and the 2t-th series resonator unit s 2t One of them is the second resonator unit 12, and the other is the fourth resonator unit 14. Moreover, the same number of surface acoustic wave resonators 10 are connected in series in the second resonator unit 12. t is a positive integer, and 2t is a positive integer not greater than N + 1. In this way, among the 1st series resonator unit s 1 to the (N + 1)-th series resonator unit s N+1 the second resonator unit 12 and the fourth resonator unit 14 can be arranged alternately periodically. This periodic arrangement method not only facilitates the process preparation of the series resonator unit, but also can better reduce the power density, so as to better reduce the non-linear response and better improve the output characteristics of the filter.

[0096] In the embodiments of the present application, both the series resonator unit and the parallel resonator unit include at least one surface acoustic wave resonator 10, and the structure of the surface acoustic wave resonator 10 can be as shown in Figure 6 and Figure 7 .

[0097] Referring to Figure 6 and Figure 7 , Figure 6 is a top view of a surface acoustic wave resonator, Figure 7 is Figure 6 a sectional view of the surface acoustic wave resonator shown along the P - P' direction. The surface acoustic wave resonator 10 includes a piezoelectric substrate 15 and an interdigital transducer 16 located on the piezoelectric substrate. The interdigital transducer 16 includes a first interdigital electrode 171 and a second interdigital electrode 172.

[0098] The first interdigital electrode 171 includes: a first bus bar 181 and a plurality of first finger bars 191 led out on the same side of the first bus bar 181. The plurality of first finger bars 191 are arranged in parallel. The second interdigital electrode 172 includes: a second bus bar 182 and a plurality of second finger bars 192 led out on the same side of the second bus bar 182. The plurality of second finger bars 192 are arranged in parallel. The first finger bars 191 and the second finger bars 192 are parallel, and the length directions of the first bus bar 181 and the second bus bar 182 are parallel.

[0099] The first finger bars 191 and the second finger bars 192 can be arranged alternately in the first direction X. The first finger bars 191 and the second finger bars 192 can both be parallel to the second direction Y, or both have the same inclination angle (less than 90°) with the second direction Y. The first bus bar 181 and the second bus bar 182 can be arranged oppositely in the second direction Y. The first bus bar 181 and the second bus bar 182 can be arranged directly opposite in the second direction Y (the length directions of both are perpendicular to the second direction Y) or be inclined and opposite in the second direction Y (the length directions of both have the same inclination angle with the first direction X). The first finger bars 191 and the second finger bars 192 are both located between the first bus bar 181 and the second bus bar 182. The first direction X and the second direction Y are perpendicular to each other and both are parallel to the plane where the piezoelectric substrate 15 is located.

[0100] In one implementation, as Figure 6 shown, in the first interdigital electrode 171, all the first finger bars 191 are located on the side of the first bus bar 181 facing the second interdigital electrode 172, and all the first finger bars 191 are arranged parallel and evenly in the first direction X. In the second interdigital electrode 172, all the second finger bars 192 are located on the side of the second bus bar 182 facing the first interdigital electrode 171, and all the second finger bars 192 are arranged parallel and evenly in the first direction X.

[0101] Refer to Figure 8 and Figure 9 , Figure 8 which is a top view of a first resonator unit provided by an embodiment of the present application. Figure 9 is Figure 8 a sectional view of the first resonator unit shown in the Q-Q' direction. On the basis of the implementation, Figure 8 and Figure 9 in the first resonator unit 11 shown, the surface acoustic wave resonators 10 share the same piezoelectric substrate 15, and the interdigital transducers 16 are connected in parallel on the same side surface of the piezoelectric substrate 15. In this way, setting all the surface acoustic wave resonators 10 in the first resonator unit 11 on the same side surface of the same piezoelectric substrate 15 can simultaneously fabricate the interdigital transducers 16 based on the same conductive layer, which is convenient for the process preparation and parallel connection of the interdigital transducers 16 in the first resonator unit 11.

[0102] Figure 8 and Figure 9 illustrate by taking the first resonator unit 11 including two surface acoustic wave resonators 10 as an example. On the same side surface of the piezoelectric substrate 15, two interdigital transducers 16 are provided, and each interdigital transducer 16 corresponds to a surface acoustic wave resonator 10.

[0103] Optionally, in the same first resonator unit 11, the interdigital transducers 16 of the surface acoustic wave resonators 10 are arranged in sequence along the first direction X; the surface acoustic wave resonators 10 share the same first bus bar 181, or the first bus bars 181 of the surface acoustic wave resonators 10 are connected to the same first connecting member 201; the surface acoustic wave resonators 10 share the same second bus bar 182, or the second bus bars 182 of the surface acoustic wave resonators 10 are connected to the same second connecting member 202.

[0104] In the same first resonator unit 11, in the manner as shown in Figure 8 and Figure 9 the first bus bars 181 of two surface acoustic wave resonators 10 can be connected to the same first connecting member 201, and the two surface acoustic wave resonators 10 can share the same second bus bar 182 to realize the parallel connection of the two surface acoustic wave resonators 10.

[0105] When the number of surface acoustic wave resonators 10 connected in parallel in the first resonator unit 11 is greater than 2, reference can be made to Figure 8 and Figure 9 shown, the interdigital transducers 16 of the surface acoustic wave resonators 10 are arranged in sequence in the first direction X, and the surface acoustic wave resonators 10 share the same first bus bar 181, or the first bus bars 181 of the surface acoustic wave resonators 10 are connected to the same first connecting member 201 to make the first finger electrodes 171 of the interdigital transducers 16 equipotential; the surface acoustic wave resonators 10 share the same second bus bar 182, or the second bus bars 182 of the surface acoustic wave resonators 10 are connected to the same second connecting member 202 to make the second finger electrodes 172 of the interdigital transducers 16 equipotential, so as to realize the parallel connection of multiple surface acoustic wave resonators 10 in the same first resonator unit 11.

[0106] Optionally, as shown in Figure 8 in the same first resonator unit 11, the interdigital transducers 16 of the surface acoustic wave resonators 10 are arranged in sequence along the first direction X, and the graphic structures of all the interdigital transducers 16 are axisymmetric based on the symmetry axis parallel to the second direction Y (in this application, the symmetry axis is represented by a vertical dotted line). Based on this symmetric design, the second-order nonlinear responses of the surface acoustic wave resonators on both sides of the symmetry axis can be made out of phase, and the second harmonic can be better cancelled.

[0107] When the graphic structures of all the interdigital transducers 16 in the same first resonator unit 11 are axisymmetric based on a symmetry axis parallel to the second direction Y, the first resonator unit 11 can be as shown in Figure 8As shown, there are interdigital transducers 16 arranged in sequence in the first direction X, that is, the first resonator unit 11 has 2 surface acoustic wave resonators 10 connected in parallel. It is also possible to have a number of interdigital transducers 16 greater than 2 arranged in sequence in the first direction X, that is, the number of surface acoustic wave resonators 10 connected in parallel in the first resonator unit 11 is greater than 2.

[0108] In one embodiment, the piezoelectric substrate 15 can be as Figure 9 shown, including a piezoelectric layer 151, and the interdigital transducer 16 is located on one side surface of the piezoelectric layer 151.

[0109] Referring to Figure 10 , Figure 10 which is a sectional view of a first resonator unit provided by an embodiment of the present application. On the basis of other embodiments, the surface acoustic wave resonator 10 further includes a temperature compensation layer 21 covering the interdigital transducer 16. The temperature compensation layer 21 can be a silicon dioxide layer to form a temperature-compensated surface acoustic wave resonator (TC-SWA) to solve the temperature drift problem through the temperature compensation layer 21.

[0110] Optionally, at least one of the first resonator unit 11, the second resonator unit 12, the third resonator unit 13, and the fourth resonator unit 14 can include a surface acoustic wave resonator 10 as Figure 10 shown.

[0111] Referring to Figure 11 , Figure 11 which is another sectional view of a first resonator unit provided by an embodiment of the present application. On the basis of the above embodiment, the piezoelectric substrate 15 includes: a substrate 152; a temperature compensation layer and a piezoelectric layer 151 laminated in sequence on the same side surface of the substrate 152; and the interdigital transducer 16 is located on the side surface of the piezoelectric layer 151 facing away from the substrate 152.

[0112] Optionally, at least one of the first resonator unit 11, the second resonator unit 12, the third resonator unit 13, and the fourth resonator unit 14 can include a surface acoustic wave resonator 10 as Figure 11 shown.

[0113] Referring to Figure 12 , Figure 12 which is yet another sectional view of a first resonator unit provided by an embodiment of the present application. On the basis of the above embodiment, the piezoelectric substrate 15 includes: a substrate 152; a high sound velocity layer 153, a temperature compensation layer 21, and a piezoelectric layer 151 laminated in sequence on the same side surface of the substrate 152; and the interdigital transducer 16 is located on the side surface of the piezoelectric layer 151 facing away from the substrate 152.

[0114] Optionally, at least one of the first resonator unit 11, the second resonator unit 12, the third resonator unit 13, and the fourth resonator unit 14 may include a surface acoustic wave resonator 10 as Figure 12 shown.

[0115] In the embodiments of the present application, the implementation manner of the piezoelectric substrate 15 can be set according to requirements, including but not limited to the manner as Figures 9 - 12 shown.

[0116] When the first resonator unit 11 includes two surface acoustic wave resonators 10 connected in parallel, as Figure 8 shown, two interdigital transducers 16 can be arranged symmetrically about the axis of symmetry; in the same interdigital transducer 16, the lengths of the first finger bars 191 and the second finger bars 192 are the same and are both parallel to the second direction Y; the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 both have the same angle with the first direction X, and this angle is greater than 0° and less than 45°.

[0117] The graphic structure of the interdigital transducer 16 in the first resonator unit 11 is not limited to the manner as Figure 8 shown, and can also be as Figure 13 and Figure 14 shown.

[0118] Referring to Figure 13 , Figure 13 is a top view of another first resonator provided by the embodiments of the present application. Different from the manner as Figure 8 shown, in Figure 13 , two interdigital transducers 16 are symmetrically arranged about the axis of symmetry; the lengths of the first finger bars 191 and the second finger bars 192 are the same; the first finger bars 191 and the second finger bars 192 are parallel; and the first finger bars 191 and the second finger bars 192 both have an angle greater than 0° and less than 45° with the second direction Y; for the same interdigital transducer 16, the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 both have the same angle with the first direction X, and this angle is greater than 0° and less than 45°.

[0119] Referring to Figure 14 , Figure 14 is a top view of yet another first resonator provided by the embodiments of the present application. Different from the manner as Figure 8 shown, in Figure 14 , two interdigital transducers 16 can be arranged symmetrically about the axis of symmetry; the lengths of the first finger bars 191 and the second finger bars 192 are the same and are both parallel to the second direction Y; the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 are both parallel to the first direction X.

[0120] In Figure 14 the manner shown, for the same first resonator unit, the first busbars of the respective interdigital transducers 16 are connected to the same first connecting member 201, and the second busbars 182 of the respective interdigital transducers 16 are connected to the same second connecting member 202.

[0121] Optionally, in the embodiments of the present application, among the interdigital transducers 16 of at least one surface acoustic wave resonator 10, as Figure 14 shown, the first busbar 181 and / or the second busbar 182 includes a hollowed-out area 22. Based on the hollowed-out area 22, the transverse mode can be suppressed, and the leakage of energy in the second direction Y can be suppressed.

[0122] Referring to Figure 15 , Figure 15 which is a top view of a second resonator provided in the embodiments of the present application. On the basis of other embodiments, Figure 15 in the second resonator unit 12 in the manner shown, the surface acoustic wave resonators 10 share the same piezoelectric substrate 15, and the interdigital transducers 16 are connected in series on the same side surface of the piezoelectric substrate 15. In this way, by arranging all the surface acoustic wave resonators 10 in the second resonator unit 12 on the same side surface of the same piezoelectric substrate 15, the interdigital transducers 16 can be simultaneously fabricated based on the same conductive layer, which is convenient for the process fabrication and series connection of the interdigital transducers 16 in the second resonator unit 12. The design of the piezoelectric substrate 15 in the second resonator unit 12 can refer to the above embodiments, and will not be elaborated in the embodiments of the present application.

[0123] As Figure 15 shown, in the same second resonator unit 12, the interdigital transducers 16 of the respective surface acoustic wave resonators 10 are arranged in sequence along the second direction Y; for two adjacent interdigital transducers 16 in the second direction Y, the adjacent busbars thereof are connected to realize the series connection between the surface acoustic wave resonators 10. In this way, the hollowed-out area 22 can also be provided in at least one busbar.

[0124] In an embodiment of the embodiments of the present application, it can be as Figure 15 shown that, in the same second resonator unit 12, for two adjacent interdigital transducers 16 in the second direction Y, the adjacent busbars thereof are the same busbar. As Figure 15 shown in, the second busbar 182 of the upper interdigital transducer 16 in can also serve as a busbar of the lower interdigital transducer 16, so that two adjacent interdigital transducers 16 in the second direction Y can share the same busbar therebetween to realize the series connection therebetween.

[0125] In Figure 15In the shown manner, both the first finger bar 191 and the second finger bar 192 are parallel to the second direction Y, and the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 are both parallel to the first direction X. As Figure 15 shown, in the second resonator unit 12, at least one bus bar can be provided to include a hollowed-out area 22.

[0126] In other manners, as Figures 16 - 19 shown, for two adjacent interdigital transducers 16 in the second direction Y, the adjacent bus bars thereof can also be connected based on the third connecting member 203 to achieve series connection therebetween.

[0127] Referring to Figure 16 , Figure 16 is a top view of another second resonator provided by an embodiment of the present application. In this manner, both the first finger bar 191 and the second finger bar 192 are parallel to the second direction Y; in the same interdigital transducer 16, the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 are parallel, and both have an angle greater than 0° and less than 45° with the first direction X. For two adjacent interdigital transducers 16 in the second direction Y, the adjacent bus bars thereof are connected by the third connecting member 203. Two adjacent interdigital transducers 16 in the second direction Y are symmetric about an axis of symmetry parallel to the first direction X.

[0128] Referring to Figure 17 , Figure 17 is a top view of yet another second resonator provided by an embodiment of the present application. In this manner, both the first finger bar 191 and the second finger bar 192 are parallel to the second direction Y, the side of the first finger bar 191 connected by the first bus bar 181 and the side of the second finger bar 192 connected by the second bus bar 182 are parallel, and both have an angle greater than 0° and less than 45° with the first direction X. For two adjacent interdigital transducers 16 in the second direction Y, the adjacent bus bars thereof are connected by the third connecting member 203. Two adjacent interdigital transducers 16 in the second direction Y are centrosymmetric about the midpoint of the third connecting member 203, that is Figure 17 the graphic structure coincides after rotating 180° around the midpoint of the third connecting member 203.

[0129] Referring to Figure 18 , Figure 18Another top view of the second resonator provided by the embodiment of the present application. In this manner, two adjacent interdigital transducers 16 in the second direction Y are symmetric about the symmetry axis parallel to the first direction X. In the same interdigital transducer 16, both the first finger bar 191 and the second finger bar 192 have an angle greater than 0° and less than 45° with the second direction Y. The angle between the finger bars of adjacent interdigital transducers 16 is greater than 90° and less than 180°. For two adjacent interdigital transducers 16 in the second direction Y, the opposite bus bars thereof have an angle greater than 0° and less than 45°, and the symmetry axis of the two bisects this angle.

[0130] Reference Figure 19 , Figure 19 Another top view of the second resonator provided by the embodiment of the present application. In this manner, two adjacent interdigital transducers 16 in the second direction Y are centrosymmetric about the midpoint of the third connecting member 203, that is Figure 19 After rotating 180° around the midpoint of the third connecting member 203, the graphic structures coincide. The first finger bar 191 and the second finger bar 192 are parallel and both have an angle greater than 0° and less than 45° with the second direction Y. For two adjacent interdigital transducers 16 in the second direction Y, their bus bars are parallel.

[0131] The embodiment of the present application provides a novel filter circuit topology. By replacing the single resonator in the conventional design shown with the first resonator unit 11 having multiple parallel surface acoustic wave resonators 10, and / or by replacing the single resonator in the conventional design shown with the second resonator unit 12 having multiple series surface acoustic wave resonators 10, the second harmonic can be reduced, and the power density and non-linear effect can be reduced. Figure 1 shown in the conventional design with a single resonator, and / or by replacing the single resonator in the conventional design shown with the second resonator unit 12 having multiple series surface acoustic wave resonators 10 Figure 1 shown in the conventional design with a single resonator, the second harmonic can be reduced, and the power density and non-linear effect can be reduced.

[0132] For the second resonator unit 12, since it includes multiple surface acoustic wave resonators 10 located on the same piezoelectric substrate 15, the resonant area can be increased while keeping the static capacitance unchanged, so that the maximum tolerable power can be greatly increased, the power density can be reduced, and thus the non-linear response can be reduced. Compared with the conventional design having one surface acoustic wave resonator 10, if the second resonator unit 12 includes two series surface acoustic wave resonators 10, the resonant area can be increased by 4 times while keeping the static capacitance unchanged.

[0133] The second resonator unit 12 increases the resonance area through a plurality of series-connected surface acoustic wave resonators 10 in series to achieve the effect of reducing the power density and reducing the non-linear response. Among them, the number of surface acoustic wave resonators 10 in series in the second resonator unit 12 is not limited to two, and can be three, four or any number. In the embodiment of the present application, the method of increasing the resonance area includes increasing the aperture of the interdigital transducer 16 and / or increasing the number of finger bars of a single interdigital transducer 16.

[0134] Relative to Figure 1 the manner shown, in the embodiment of the present application, the series resonator unit with the smallest resonance area can be replaced by the second resonator unit 12, or a plurality of series resonator units with a resonance area smaller than a certain threshold can be replaced by the second resonator unit 12.

[0135] Referring to Figure 20 , Figure 20 is a test curve of the second harmonic of two surface acoustic wave resonators in parallel. The horizontal axis is the frequency / GHz, and the vertical axis is the second harmonic intensity / dBm. The comparative example is the test curve of the second harmonic of a single surface acoustic wave resonator 10 with the same static capacitance. By comparing the test curves of the comparative example and the embodiment of the present application, it can be seen that after the surface acoustic wave resonators 10 are connected in parallel, under the same static capacitance, the second harmonic of the embodiment of the present application is significantly weakened.

[0136] For the first resonator unit 11, since it includes a plurality of surface acoustic wave resonators 10 connected in parallel, it is possible to cancel the second harmonic based on the inverse phase of the second non-linear responses of different surface acoustic wave resonators 10. Optionally, it can be set that the first resonator unit 11 includes two surface acoustic wave resonators 10 connected in parallel, and the graphic structures of the interdigital transducers 16 of the two surface acoustic wave resonators 10 connected in parallel are axially symmetric, so as to better achieve the inverse phase of the second non-linear responses of the two surface acoustic wave resonators 10 and better cancel the second harmonic.

[0137] In the embodiment of the present application, for the surface acoustic wave resonator 10, the first finger bar 191 and the second finger bar 192 can be set to have a graphic structure with a uniform line width, or as Figure 14 or Figure 15 shown, the first finger bar 191 and the second finger bar 192 are set to have a piston structure.

[0138] For the first resonator unit 11 and the second resonator unit 12, as Figure 8 , Figures 13 - 19 shown in any one of the ways, the performance of suppressing the transverse mode can be optimized by any one of the ways of setting a plug structure on the finger bar, inclining the bus bar relative to the first direction X (the finger bar can remain parallel to the second direction Y), and rotating the interdigital transducer 16 (at least the finger bar has a rotation angle with the second direction Y).

[0139] The embodiments of the present application are compatible with existing manufacturing processes, and the manufacturing processes can be simply implemented on the existing manufacturing processes, and the manufacturing processes are simple.

[0140] Based on the above embodiments, another embodiment of the present application further provides a radio frequency module, and the radio frequency module includes the filter circuit topology provided by any one of the above embodiments.

[0141] The radio frequency module provided by the embodiments of the present application adopts the filter circuit topology provided by the above embodiments, and can reduce the second harmonic in the parallel resonator unit through the first resonator unit 11, and can reduce the power density of the series resonator unit through the second resonator unit 12.

[0142] Based on the above embodiments, another embodiment of the present application further provides an electronic device, and the electronic device includes the above radio frequency module.

[0143] Optionally, the electronic device can be a wireless communication device such as a smart phone, a satellite communication device, a radar system, etc. The embodiments of the present application do not limit the type of the electronic device, and can be any electronic device with a radio frequency module. The electronic device includes the performance of the above radio frequency module, can reduce the second harmonic in the parallel resonator unit, and can reduce the power density of the series resonator unit.

[0144] The various embodiments in the description of the present application are described in a progressive, or parallel, or a combination of progressive and parallel manners. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. The embodiments provided by the embodiments of the present application can be combined with each other without conflict.

[0145] It should be noted that in the description of the present application, it should be understood that the descriptions of the drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structures. Additionally, for the sake of understanding and ease of description, the drawings may exaggerate the thickness of some layers, films, panels, regions, etc. At the same time, it can be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element can be directly on the other element or there can be intervening elements. Additionally, "on..." means positioning the element on or below another element, but does not inherently mean positioning on the upper side of another element according to the direction of gravity.

[0146] The orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be intermediate components present simultaneously.

[0147] It should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the article or device comprising the above elements.

[0148] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A filter circuit topology structure, characterized in that: include: Input and output terminals; N+1 series resonator units are sequentially connected between the input end and the output end, and on the series path from the input end to the output end, the N+1 series resonator units are sequentially from the first series resonator unit to the N+1th series resonator unit; An i-th parallel node is provided between the i-th series resonator unit and the i+1-th series resonator unit; N parallel resonator units, which are the first parallel resonator unit to the Nth parallel resonator unit in sequence; the i-th parallel node is connected to the ground terminal through the i-th parallel resonator unit, N is a positive integer, and i is a positive integer not greater than N; At least one of the first to Nth parallel resonator units is a first resonator unit, and the first resonator unit includes a plurality of surface acoustic wave resonators connected in parallel between corresponding parallel nodes and the ground end.

2. The filter circuit topology structure according to claim 1, characterized in that: The surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate; In the first resonator unit, the surface acoustic wave resonators share the same piezoelectric substrate, and the interdigital transducers are connected in parallel on the same side surface of the piezoelectric substrate.

3. The filter circuit topology structure according to claim 2, characterized in that: The interdigital transducer comprises a first interdigital electrode and a second interdigital electrode; the first interdigital electrode comprises a first bus bar and a plurality of first fingers extending from the same side of the first bus bar; the second interdigital electrode comprises a second bus bar and a plurality of second fingers extending from the same side of the second bus bar; the first fingers and the second fingers are alternately arranged in a first direction, the first bus bar and the second bus bar are arranged opposite to each other in a second direction, and the first fingers and the second fingers are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and are both parallel to the plane where the piezoelectric substrate is located; In the same first resonator unit, the interdigital transducers of each of the surface acoustic wave resonators are arranged in sequence along the first direction; the surface acoustic wave resonators share the same first bus bar, or the first bus bars of the surface acoustic wave resonators are all connected to the same first connecting member; the surface acoustic wave resonators share the same second bus bar, or the second bus bars of the surface acoustic wave resonators are connected to the same second connecting member.

4. The filter circuit topology structure according to claim 2, characterized in that: In the same first resonator unit, the interdigital transducers of each of the surface acoustic wave resonators are arranged in sequence along a first direction, and the graphic structures of all the interdigital transducers are axially symmetrical based on a symmetry axis parallel to a second direction; the first direction and the second direction are perpendicular to each other and are both parallel to the plane where the piezoelectric substrate is located.

5. The filter circuit topology structure according to claim 1, characterized in that: At least one of the first to N+1th series resonator units is a second resonator unit, and the second resonator unit includes a plurality of surface acoustic wave resonators sequentially connected in series on the series path.

6. The filter circuit topology structure according to claim 5, characterized in that: The surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate; In the second resonator unit, the surface acoustic wave resonators share the same piezoelectric substrate, and the interdigital transducers are connected in series on the same side surface of the piezoelectric substrate.

7. The filter circuit topology structure according to claim 6, characterized in that: The interdigital transducer comprises a first interdigital electrode and a second interdigital electrode; the first interdigital electrode comprises a first bus bar and a plurality of first fingers extending from the same side of the first bus bar; the second interdigital electrode comprises a second bus bar and a plurality of second fingers extending from the same side of the second bus bar; the first fingers and the second fingers are alternately arranged in a first direction, the first bus bar and the second bus bar are arranged opposite to each other in a second direction, and the first fingers and the second fingers are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and are both parallel to the plane where the piezoelectric substrate is located; In the same second resonator unit, the IDTs of the surface acoustic wave resonators are arranged in sequence along the second direction; for two adjacent IDTs in the second direction, adjacent bus bars of the two IDTs are connected.

8. The filter circuit topology structure according to claim 7, characterized in that: In the same second resonator unit, for two adjacent IDTs in the second direction, the two adjacent bus bars are the same bus bar, or the two adjacent bus bars are connected via a third connecting member.

9. The filter circuit topology structure according to claim 5, characterized in that: At least the Ath series resonator unit and the Bth series resonator unit are the second resonator unit; A and B are both positive integers not greater than N+1, and A is smaller than B; The Ath series resonator unit has a number of the surface acoustic wave resonators connected in series, and the Bth series resonator unit has b number of the surface acoustic wave resonators connected in series; a and b are both positive integers greater than 1, and a is less than b.

10. The filter circuit topology structure according to claim 1, characterized in that: The surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate; The interdigital transducer comprises a first interdigital electrode and a second interdigital electrode; The first interdigitated electrode comprises a first bus bar and a plurality of first fingers extending from the same side of the first bus bar; the second interdigitated electrode comprises a second bus bar and a plurality of second fingers extending from the same side of the second bus bar; the first fingers and the second fingers are alternately arranged in a first direction, the first bus bar and the second bus bar are arranged opposite to each other in a second direction, and the first fingers and the second fingers are both located between the first bus bar and the second bus bar; the first direction and the second direction are perpendicular to each other and are both parallel to the plane where the piezoelectric substrate is located; Wherein, the first bus bar and / or the second bus bar includes a hollow area.

11. The filter circuit topology structure according to any one of claims 1 to 10, characterized in that: At least the Cth parallel resonator unit and the Dth parallel resonator unit are the first resonator unit; C and D are both positive integers not greater than N, and C is less than D; The Cth parallel resonator unit has c surface acoustic wave resonators connected in parallel, and the Dth parallel resonator unit has d surface acoustic wave resonators connected in parallel; c and d are both positive integers greater than 1, and c is less than d.

12. A radio frequency module, characterized in that: Comprising a filter circuit topology structure as described in any one of claims 1-11.

13. An electronic device, characterized in that: include: The radio frequency module as claimed in claim 12.

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