Longitudinal coupling resonator type surface acoustic wave filter, multiplexer and radio frequency front-end circuit

Abstract

The invention discloses a longitudinal coupling resonator type surface acoustic wave filter, a multiplexer and a radio frequency front-end circuit. The longitudinal coupled resonator type surface acoustic wave filter comprises an input terminal, an output terminal, a dual-mode acoustic wave filter and a capacitor, the dual-mode acoustic wave filter comprises a first terminal, a second terminal and a grounding terminal, the first terminal is electrically connected with the input end, the second terminal is electrically connected with the output end, and the grounding terminal is grounded; and the capacitor is arranged between the grounding terminal and the ground. The capacitor is arranged between the grounding terminal of the dual-mode acoustic wave filter and the ground, so that new resonance zero points can be introduced to the left side and the right side of the passband of the longitudinal coupled resonator type surface acoustic wave filter, and the out-of-band rejection of the longitudinal coupled resonator type surface acoustic wave filter can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a longitudinally coupled resonator type surface acoustic wave filter, a multiplexer and a radio frequency front-end circuit. Background Art

[0002] In mobile phones, base stations and other communication equipment, the frequency bands used are becoming more and more dense. In order to improve communication quality and reduce interference between frequency bands, surface acoustic wave filters are used to filter unwanted RF signals and improve the performance of receiving or transmitting channels.

[0003] There are mainly two types of surface acoustic wave filters: ladder topology surface acoustic wave filters and longitudinally coupled resonator surface acoustic wave filters. Among them, the dual-mode acoustic wave filter (DMS) in the longitudinally coupled resonator surface acoustic wave filter has advantages in out-of-band suppression and size, so it is widely used in surface acoustic wave filter design.

[0004] However, as users' requirements for communication quality become higher and higher, the surface acoustic wave filter needs to have better suppression outside its passband. The existing longitudinally coupled resonator type surface acoustic wave filter with dual-mode acoustic wave filter (DMS) is no longer sufficient to meet the increasingly high out-of-band suppression requirements. Summary of the invention

[0005] The present invention provides a longitudinally coupled resonator type surface acoustic wave filter, a multiplexer and a radio frequency front-end circuit to solve the problem that the existing surface acoustic wave filter with a dual-mode acoustic wave filter (DMS) is insufficient to meet the increasingly high out-of-band suppression requirements.

[0006] In a first aspect, an embodiment of the present invention provides a longitudinally coupled resonator type surface acoustic wave filter, the longitudinally coupled resonator type surface acoustic wave filter comprising: an input terminal, an output terminal, a dual-mode acoustic wave filter and a capacitor;

[0007] The dual-mode acoustic wave filter comprises a first terminal, a second terminal and a ground terminal, wherein the first terminal is electrically connected to the input terminal, the second terminal is electrically connected to the output terminal, and the ground terminal is grounded;

[0008] The capacitor is arranged between the ground terminal and the ground.

[0009] Optionally, the longitudinally coupled resonator type surface acoustic wave filter further includes a first grounding solder ball and a second grounding solder ball, the first grounding solder ball is grounded, and the second grounding solder ball is grounded; the capacitor includes a first capacitor; the grounding terminal includes a first grounding terminal and a second grounding terminal;

[0010] The first capacitor is arranged between the first ground terminal and the first ground solder ball;

[0011] Alternatively, the first capacitor is arranged between the first ground terminal and the second ground solder ball

[0012] Alternatively, the first capacitor is arranged between the second ground terminal and the first ground solder ball;

[0013] Alternatively, the first capacitor is arranged between the second ground terminal and the second ground solder ball.

[0014] Optionally, the longitudinally coupled resonator type surface acoustic wave filter further includes a first grounding solder ball and a second grounding solder ball, the first grounding solder ball is grounded, and the second grounding solder ball is grounded; the capacitor includes a second capacitor and a third capacitor; the grounding terminal includes a first grounding terminal and a second grounding terminal;

[0015] The second capacitor is arranged between the first ground terminal and the first ground solder ball, and the third capacitor is arranged between the second ground terminal and the second ground solder ball;

[0016] Alternatively, the second capacitor is arranged between the first ground terminal and the second ground solder ball, and the third capacitor is arranged between the second ground terminal and the first ground solder ball.

[0017] Optionally, the longitudinally coupled resonator type surface acoustic wave filter further includes an inductor, a first grounding solder ball and a second grounding solder ball, the first grounding solder ball is grounded, and the second grounding solder ball is grounded; the capacitor includes a fourth capacitor; the grounding terminal includes a first grounding terminal and a second grounding terminal;

[0018] The inductor is arranged between the first ground terminal and the first ground solder ball, and the fourth capacitor is arranged between the second ground terminal and the second ground solder ball;

[0019] Alternatively, the second capacitor is arranged between the first ground terminal and the second ground solder ball, and the third capacitor is arranged between the second ground terminal and the first ground solder ball.

[0020] Optionally, the capacitor includes an interdigital capacitor or a flat plate capacitor.

[0021] Optionally, the capacitance value C of the capacitor satisfies 0.1pF≤C≤1pF.

[0022] Optionally, the inductance value L of the inductor satisfies 0.01nH≤L≤0.1nH.

[0023] Optionally, the longitudinally coupled resonator type surface acoustic wave filter further includes a series resonator and a parallel resonator;

[0024] The series resonator and the dual-mode acoustic wave filter are connected in series between the input terminal and the output terminal;

[0025] One end of the parallel resonator is electrically connected to one end of the series resonator or the first terminal or the second terminal, and the other end of the parallel resonator is grounded.

[0026] In a second aspect, an embodiment of the present invention provides a surface acoustic wave multiplexer, including an antenna, at least one receiving unit and at least one transmitting unit;

[0027] The antenna is communicatively connected to the receiving unit and the sending unit respectively;

[0028] At least one of the receiving unit and the transmitting unit includes the longitudinally coupled resonator-type surface acoustic wave filter as described in the first aspect.

[0029] In a third aspect, an embodiment of the present invention provides a radio frequency front-end circuit, comprising the surface acoustic wave multiplexer as described in the second aspect.

[0030] The technical solution of the embodiment of the present invention can introduce new resonance zeros on the left and right sides of the passband of the longitudinally coupled resonator type surface acoustic wave filter by arranging a capacitor between the ground terminal of the dual-mode acoustic wave filter and the ground, which is beneficial to improving the out-of-band suppression of the longitudinally coupled resonator type surface acoustic wave filter and solves the problem that the existing longitudinally coupled resonator type surface acoustic wave filter with a dual-mode acoustic wave filter (DMS) is no longer sufficient to meet the increasingly higher out-of-band suppression requirements.

[0031] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A circuit diagram of a longitudinally coupled resonator type surface acoustic wave filter provided by the prior art;

[0034] Figure 2 for Figure 1 A schematic diagram of the structure of a longitudinally coupled resonator type surface acoustic wave filter provided;

[0035] Figure 3 A schematic circuit diagram of a longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention;

[0036] Figure 4 for Figure 3 A schematic diagram of the structure of a longitudinally coupled resonator type surface acoustic wave filter provided;

[0037] Figure 5 for Figure 1 and Figure 3 A performance comparison diagram of the provided longitudinally coupled resonator type surface acoustic wave filter;

[0038] Figure 6 for Figure 1 and Figure 3 Another performance comparison diagram of the provided longitudinally coupled resonator type surface acoustic wave filter;

[0039] Figure 7 A schematic structural diagram of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention;

[0040] Figure 8 A schematic structural diagram of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention;

[0041] Fig. 9 A schematic structural diagram of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention;

[0042] Fig.10 A schematic structural diagram of a surface acoustic wave multiplexer provided in an embodiment of the present invention;

[0043] Fig.11 A schematic structural diagram of a radio frequency front-end circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only used to illustrate the relative positional relationship between the components or components, and does not particularly limit the specific installation orientation of the components or components.

[0046] Figure 1 A circuit diagram of a longitudinally coupled resonator type surface acoustic wave filter provided by the prior art, Figure 2 for Figure 1 The schematic diagram of the longitudinally coupled resonator type surface acoustic wave filter provided by reference Figure 1 and Figure 2 The longitudinally coupled resonator type surface acoustic wave filter 10 in the prior art includes an input terminal 11, an output terminal 12, a dual-mode acoustic wave filter 13, a series resonator 14, a parallel resonator 15 and at least two grounding balls. Specifically, Figure 1 and Figure 2The longitudinally coupled resonator type surface acoustic wave filter 10 in the prior art shown includes a dual-mode acoustic wave filter 13, a series resonator 14, two parallel resonators 15 and two grounding balls. The two parallel resonators 15 are respectively a first parallel resonator 151 and a second parallel resonator 152. The two grounding balls are respectively a first grounding ball Q1 and a second grounding ball Q2. The first grounding ball Q1 is grounded, and the second grounding ball Q2 is grounded. The dual-mode acoustic wave filter 13 includes a first terminal N1, a second terminal N2 and two grounding terminals N3. The two grounding terminals N3 are respectively a first grounding terminal N31 and a second grounding terminal N32. The first grounding terminal N31 is electrically connected to the first grounding ball Q1, and the second grounding terminal N32 is electrically connected to the second grounding ball Q2. The dual-mode acoustic wave filter 13 and the series resonator 14 are connected in series between the input terminal 11 and the output terminal 12. One end of the first parallel resonator 151 is electrically connected to the input end 11 and the first end N1 of the dual-mode acoustic wave filter 13, respectively, and the other end of the first parallel resonator 151 is grounded to GND through the first grounding bump Q1. One end of the second parallel resonator 152 is electrically connected to one end of the series resonator 14 and the second end N2 of the dual-mode acoustic wave filter 13, respectively, and the other end of the second parallel resonator 152 is grounded to GND through the second grounding bump Q2.

[0047] Figure 3 A circuit diagram of a longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention, Figure 4 for Figure 3 The schematic diagram of the longitudinally coupled resonator type surface acoustic wave filter provided by reference Figure 3 and Figure 4 The longitudinal coupling resonator type surface acoustic wave filter 20 in the embodiment of the present invention includes: an input terminal 21, an output terminal 22, a dual-mode acoustic wave filter 23 and a capacitor 24. The dual-mode acoustic wave filter 23 includes a first terminal K1, a second terminal K2 and a ground terminal K3, the first terminal K1 is electrically connected to the input terminal 21, the second terminal K2 is electrically connected to the output terminal 22, and the ground terminal K3 is grounded GND. The capacitor 24 is arranged between the ground terminal K3 and the ground GND.

[0048] Optional, reference Figure 3 and Figure 4 The longitudinally coupled resonator type surface acoustic wave filter 20 further includes a series resonator 25 and a parallel resonator 26. The series resonator 25 is connected in series with the dual-mode acoustic wave filter 23 between the input terminal 21 and the output terminal 22. One end of the parallel resonator 26 is electrically connected to one end of the series resonator 25 or the first terminal K1 or the second terminal K2, and the other end of the parallel resonator 26 is grounded GND. Figure 3 and Figure 4 The longitudinally coupled resonator type surface acoustic wave filter 20 further includes at least two ground solder balls.

[0049] For example, Figure 3 and Figure 4 The longitudinal coupling resonator type surface acoustic wave filter 20 in the embodiment of the present invention shown includes a dual-mode acoustic wave filter 23, a series resonator 25, two parallel resonators 26 and two grounding solder balls. The two parallel resonators 26 are respectively a first parallel resonator 261 and a second parallel resonator 262. The two grounding solder balls are respectively a first grounding solder ball B1 and a second grounding solder ball B2. The first grounding solder ball B1 is grounded, and the second grounding solder ball B2 is grounded. The dual-mode acoustic wave filter 23 includes a first terminal K1, a second terminal K2 and two grounding terminals K3. The two grounding terminals K3 are respectively a first grounding terminal K31 and a second grounding terminal K32. The first grounding terminal K31 is electrically connected to the first grounding solder ball B1, and the second grounding terminal K32 is electrically connected to the second grounding solder ball B2. The dual-mode acoustic wave filter 13 and the series resonator 25 are connected in series between the input terminal 21 and the output terminal 22. One end of the first parallel resonator 261 is electrically connected to the input terminal 11 and the first terminal K1 of the dual-mode acoustic wave filter 23, respectively, and the other end of the first parallel resonator 261 is grounded to GND through the first grounding solder ball B1. One end of the second parallel resonator 262 is electrically connected to one end of the series resonator 25 and the second terminal K2 of the dual-mode acoustic wave filter 23, respectively, and the other end of the second parallel resonator 262 is grounded to GND through the second grounding solder ball B2.

[0050] Figure 3 and Figure 4 The longitudinally coupled resonator type surface acoustic wave filter 20 in the embodiment of the present invention shown in FIG. Figure 1 and Figure 2 Compared with the surface acoustic wave filter 10 in the prior art shown in the figure, the only difference is that a capacitor 24 is provided between the ground terminal K3 of the dual-mode acoustic wave filter 23 and the ground GND. Figure 3 and Figure 4 , the capacitor 24 is arranged between the second ground terminal K32 and the ground GND.

[0051] Figure 5 for Figure 1 and Figure 3 A performance comparison chart of the longitudinally coupled resonator type surface acoustic wave filter provided, Figure 6 for Figure 1 and Figure 3 Another performance comparison chart of the longitudinally coupled resonator type surface acoustic wave filter provided. It should be noted that S1 represents Figure 1 The performance curve of the longitudinally coupled resonator type surface acoustic wave filter provided when its surface acoustic wave frequency is 650MHZ-810MHZ, S2 represents Figure 1The performance curve of the longitudinally coupled resonator type surface acoustic wave filter provided when its surface acoustic wave frequency is 650MHZ-810MHZ, S3 represents Figure 1 The performance curve of the longitudinally coupled resonator type surface acoustic wave filter provided when its surface acoustic wave frequency is 0MHZ-6000MHZ, S4 represents Figure 1 The performance curve of the longitudinally coupled resonator type surface acoustic wave filter provided when its surface acoustic wave frequency is 0MHZ-6000MHZ is referenced Figure 5 and Figure 6 It can be seen that compared with the surface acoustic wave filter in the prior art, the longitudinally coupled resonator type surface acoustic wave filter in the embodiment of the present invention introduces new resonant zeros within 700-720 MHz on the left side of the passband and within 1000-5000 MHz on the right side of the passband, and the out-of-band suppression is significantly improved.

[0052] The technical solution of the embodiment of the present invention can introduce new resonance zeros on the left and right sides of the passband of the longitudinally coupled resonator type surface acoustic wave filter 20 by setting a capacitor 24 between the ground terminal K3 of the dual-mode acoustic wave filter 23 and the ground GND, which is beneficial to improving the out-of-band suppression of the longitudinally coupled resonator type surface acoustic wave filter 20, and solves the problem that the existing longitudinally coupled resonator type surface acoustic wave filter with a dual-mode acoustic wave filter (DMS) is no longer sufficient to meet the increasingly higher out-of-band suppression requirements.

[0053] It should be noted that the embodiment of the present invention does not limit the number of dual-mode acoustic wave filters 23, the number of series resonators 25, and the number of parallel resonators 26 included in the surface acoustic wave filter 20, and those skilled in the art can set them according to actual needs.

[0054] Figure 7 A schematic diagram of the structure of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention, referring to Figure 7 , the longitudinally coupled resonator type surface acoustic wave filter also includes a first grounding solder ball B1 and a second grounding solder ball B2, the first grounding solder ball B1 is grounded, and the second grounding solder ball B2 is grounded. The capacitor 24 includes a first capacitor 241. The grounding terminal K3 includes a first grounding terminal K31 and a second grounding terminal K32. The first capacitor 241 is arranged between the first grounding terminal K31 and the first grounding solder ball B1; or, the first capacitor 241 is arranged between the first grounding terminal K31 and the second grounding solder ball B2; or, the first capacitor 241 is arranged between the second grounding terminal K32 and the first grounding solder ball B1; or, the first capacitor 241 is arranged between the second grounding terminal K32 and the second grounding solder ball B2.

[0055] Figure 7The longitudinally coupled resonator type surface acoustic wave filter shown includes two dual-mode acoustic wave filters 23 connected in series. Specifically, the two dual-mode acoustic wave filters 23 are respectively a first dual-mode acoustic wave filter 231 and a second dual-mode acoustic wave filter 232, the first dual-mode acoustic wave filter 231 and the second dual-mode acoustic wave filter 232 are connected in series between the input terminal 21 and the output terminal 22, the first terminal K1 of the first dual-mode acoustic wave filter 231 is electrically connected to the input terminal 21, and the second terminal ( Figure 7 not shown) and the first terminal ( Figure 7 The first dual-mode acoustic wave filter 231 is electrically connected to the first capacitor 241 (not shown), and the second terminal K2 of the second dual-mode acoustic wave filter 232 is electrically connected to the output terminal 22. The first grounding terminal K31 of the first dual-mode acoustic wave filter 231 is grounded through the first grounding solder ball B1, and the second grounding terminal K32 of the first dual-mode acoustic wave filter 231 is electrically connected to one end of the first capacitor 241, and the other end of the first capacitor 241 is electrically connected to the first grounding solder ball B1. The first grounding terminal K31 of the second dual-mode acoustic wave filter 232 is grounded through the second grounding solder ball B2, and the second grounding terminal K32 of the second dual-mode acoustic wave filter 232 is grounded through the second grounding solder ball B2.

[0056] It should be noted that Figure 7 The illustrated embodiment only shows that the first capacitor 241 is set between the second ground terminal K32 of the first dual-mode acoustic wave filter 231 and the first ground solder ball B1. It can be understood that the first capacitor 241 can also be set between the first ground terminal K31 and the first ground solder ball B1 of the first dual-mode acoustic wave filter 231, between the first ground terminal K31 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232, and between the second ground terminal K32 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232.

[0057] Figure 8 A schematic diagram of the structure of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention, referring to Figure 8 , the longitudinally coupled resonator type surface acoustic wave filter also includes a first grounding solder ball B1 and a second grounding solder ball B2, the first grounding solder ball B1 is grounded, and the second grounding solder ball B2 is grounded. The capacitor 24 includes a second capacitor 242 and a third capacitor 243. The grounding terminal K3 includes a first grounding terminal K31 and a second grounding terminal K32. The second capacitor 242 is arranged between the first grounding terminal K31 and the first grounding solder ball B1, and the third capacitor 243 is arranged between the second grounding terminal K32 and the second grounding solder ball B2; or, the second capacitor 242 is arranged between the first grounding terminal K31 and the second grounding solder ball B2, and the third capacitor 243 is arranged between the second grounding terminal K32 and the first grounding solder ball B1.

[0058] Figure 8 The longitudinally coupled resonator type surface acoustic wave filter shown includes two dual-mode acoustic wave filters 23 connected in series. Specifically, the two dual-mode acoustic wave filters 23 are respectively a first dual-mode acoustic wave filter 231 and a second dual-mode acoustic wave filter 232, the first dual-mode acoustic wave filter 231 and the second dual-mode acoustic wave filter 232 are connected in series between the input terminal 21 and the output terminal 22, the first terminal K1 of the first dual-mode acoustic wave filter 231 is electrically connected to the input terminal 21, and the second terminal ( Figure 8 not shown) and the first terminal ( Figure 8 The first dual-mode acoustic wave filter 231 is electrically connected to the output terminal 22 (not shown), and the second terminal K2 of the second dual-mode acoustic wave filter 232 is electrically connected to the output terminal 22. The first grounding terminal K31 of the first dual-mode acoustic wave filter 231 is grounded through the first grounding solder ball B1, the second grounding terminal K32 of the first dual-mode acoustic wave filter 231 is electrically connected to one end of the third capacitor 243, and the other end of the third capacitor 243 is electrically connected to the first grounding solder ball B1. The first grounding terminal K31 of the second dual-mode acoustic wave filter 232 is electrically connected to one end of the second capacitor 242, and the other end of the second capacitor 242 is electrically connected to the second grounding solder ball B2, and the second grounding terminal K32 of the second dual-mode acoustic wave filter 232 is grounded through the second grounding solder ball B2.

[0059] It should be noted that Figure 8 The illustrated embodiment only shows that the third capacitor 243 is provided between the second ground terminal K32 and the first ground solder ball B1 of the first dual-mode acoustic wave filter 231, and the second capacitor 242 is provided between the first ground terminal K31 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232. It can be understood that the second capacitor 242 can also be provided between the first ground terminal K31 and the first ground solder ball B1 of the first dual-mode acoustic wave filter 231, and the third capacitor 243 can also be provided between the second ground terminal K32 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232.

[0060] Fig. 9 A schematic diagram of the structure of another longitudinally coupled resonator type surface acoustic wave filter provided by an embodiment of the present invention, referring to Fig. 9, the longitudinally coupled resonator type surface acoustic wave filter 20 also includes an inductor 27, a first grounding solder ball B1 and a second grounding solder ball B2, the first grounding solder ball B1 is grounded, and the second grounding solder ball B2 is grounded. The capacitor 24 includes a fourth capacitor 244. The grounding terminal K3 includes a first grounding terminal K31 and a second grounding terminal K32. The inductor 27 is arranged between the first grounding terminal K31 and the first grounding solder ball B1, and the fourth capacitor 244 is arranged between the second grounding terminal K32 and the second grounding solder ball B2; or, the inductor 27 is arranged between the first grounding terminal K31 and the second grounding solder ball B2, and the fourth capacitor 244 is arranged between the second grounding terminal K32 and the first grounding solder ball B1.

[0061] Fig. 9 The longitudinally coupled resonator type surface acoustic wave filter shown includes two dual-mode acoustic wave filters 23 connected in series. Specifically, the two dual-mode acoustic wave filters 23 are respectively a first dual-mode acoustic wave filter 231 and a second dual-mode acoustic wave filter 232, the first dual-mode acoustic wave filter 231 and the second dual-mode acoustic wave filter 232 are connected in series between the input terminal 21 and the output terminal 22, the first terminal K1 of the first dual-mode acoustic wave filter 231 is electrically connected to the input terminal 21, and the second terminal ( Fig. 9 not shown) and the first terminal ( Fig. 9 The first terminal K31 of the first dual-mode acoustic wave filter 231 is electrically connected to the output terminal 22 (not shown), and the second terminal K2 of the second dual-mode acoustic wave filter 232 is electrically connected to the output terminal 22. The first grounding terminal K31 of the first dual-mode acoustic wave filter 231 is grounded through the first grounding solder ball B1, and the second grounding terminal K32 of the first dual-mode acoustic wave filter 231 is electrically connected to one end of the fourth capacitor 244, and the other end of the fourth capacitor 244 is electrically connected to the first grounding solder ball B1. The first grounding terminal K31 of the second dual-mode acoustic wave filter 232 is electrically connected to one end of the inductor 27, and the other end of the inductor 27 is electrically connected to the first grounding solder ball B1, and the second grounding terminal K32 of the second dual-mode acoustic wave filter 232 is grounded through the second grounding solder ball B2.

[0062] It should be noted that Fig. 9 The illustrated embodiment only shows that the fourth capacitor 244 is provided between the second ground terminal K32 and the first ground solder ball B1 of the first dual-mode acoustic wave filter 231, and the inductor 27 is provided between the first ground terminal K31 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232. It can be understood that the fourth capacitor 244 can also be provided between the second ground terminal K32 and the second ground solder ball B2 of the second dual-mode acoustic wave filter 232, and the inductor 27 can also be provided between the first ground terminal K31 and the first ground solder ball B1 of the first dual-mode acoustic wave filter 231.

[0063] Figure 3 and Figure 4 The dual-mode acoustic wave filter 23 in is of fifth order, Figure 7 , Figure 8 and Fig. 9 The dual-mode acoustic wave filter 23 is of third order. It should be noted that the embodiment of the present invention does not limit the order of the dual-mode acoustic wave filter 23, and those skilled in the art can set it according to their needs.

[0064] As a feasible implementation, the capacitor 24 includes an interdigital capacitor or a plate capacitor.

[0065] refer to Figure 3 , Figure 4 , Figure 7 , Figure 8 and Fig. 9 The capacitor 24 in the embodiment of the present invention can be a forked-finger capacitor, which can be prepared together with the metal trace when preparing the metal trace for connecting the ground terminal K3 and the ground solder ball (the first ground solder ball B1 or the second ground solder ball B2) in the longitudinally coupled resonator type surface acoustic wave filter.

[0066] As a feasible implementation, the inductor 27 includes a winding inductor.

[0067] refer to Fig. 9 In the embodiment of the present invention, a winding inductor can be used. The winding inductor can be prepared together with the metal routing when preparing the metal routing used to connect the ground terminal K3 and the ground solder ball (the first ground solder ball B1 or the second ground solder ball B2) in the longitudinally coupled resonator type surface acoustic wave filter.

[0068] It should be noted that the capacitance C of the capacitor 24 in the embodiment of the present invention needs to satisfy 0.1 pF≤C≤1 pF. The inductance L of the inductor 27 in the embodiment of the present invention needs to satisfy 0.01 nH≤L≤0.1 nH.

[0069] Based on the same inventive concept, the embodiment of the present invention further provides a surface acoustic wave multiplexer 30, Fig.10 A schematic diagram of a surface acoustic wave multiplexer provided in an embodiment of the present invention, referring to Fig.10 The surface acoustic wave multiplexer 30 in the embodiment of the present invention includes an antenna 31, at least one receiving unit 32 and at least one transmitting unit 33. The antenna 31 is connected to the receiving unit 32 and the transmitting unit 33 for communication. At least one of the receiving unit 32 and the transmitting unit 33 includes the longitudinally coupled resonator type surface acoustic wave filter 20 in the above embodiment. Therefore, the surface acoustic wave multiplexer 30 includes the technical features of the longitudinally coupled resonator type surface acoustic wave filter 20, and has the beneficial effects of the longitudinally coupled resonator type surface acoustic wave filter 20. The same points can be referred to the above description.

[0070] Exemplarily, the surface acoustic wave multiplexer 30 is taken as a surface acoustic wave duplexer for example, the receiving unit 32 is arranged between the antenna 31 and the receiving terminal P1, and forms a first passband of the surface acoustic wave duplexer, and the transmitting unit 33 is arranged between the antenna 31 and the transmitting terminal P2, and forms a second passband of the surface acoustic wave duplexer. It should be noted that the receiving unit 32 may include the following: Figure 3 , Figure 4 , Figure 7 , Figure 8 or Fig. 9 The longitudinally coupled resonator type surface acoustic wave filter 20 is shown. The transmitting unit 33 may include Figure 3 , Figure 4 , Figure 7 , Figure 8 or Fig. 9 A longitudinally coupled resonator type surface acoustic wave filter 20 is shown.

[0071] It can be understood that when the surface acoustic wave multiplexer 30 is a quadplexer, the quadplexer includes four terminals, an antenna and four surface acoustic wave filters, a passband is formed between each terminal and the antenna, and at least one of the four surface acoustic wave filters includes the longitudinally coupled resonator type surface acoustic wave filter 20 in the above embodiment.

[0072] Based on the same inventive concept, an embodiment of the present invention further provides a radio frequency front-end circuit 40, Fig.11 A schematic diagram of a radio frequency front-end circuit according to an embodiment of the present invention is provided. Fig.11 The radio frequency front-end circuit 40 in the embodiment of the present invention includes the surface acoustic wave multiplexer 30 in the above embodiment.

[0073] refer to Fig.11 The RF front-end circuit 40 includes a switch 41, a first surface acoustic wave filter 42, a second surface acoustic wave filter 43, a first duplexer (the first duplexer includes a first duplexer transmit filter 44 and a first duplexer receive filter 45), a second duplexer (the second duplexer includes a second duplexer transmit filter 46 and a second duplexer receive filter 47), a low noise amplifier 48 and a power amplifier 49.

[0074] Specifically, the RF front-end circuit 40 is connected to the RF signal processing circuit 52 and the baseband signal processing circuit 53 to form the RF communication device 50 .

[0075] Further, the switch 41 is used to control the RF signal, connect the antenna terminal 51 to at least one signal path corresponding to a given frequency band, and the at least one signal path connected to the antenna terminal 51 may also be multiple signal paths (corresponding to multiple filters and duplexers). The RF front-end circuit 40 can support carrier aggregation technology. The low noise amplifier 48 amplifies the RF signal fed via the antenna terminal 51, the switch 41, the first duplexer receiving filter 45, and the second duplexer receiving filter 47, and feeds the amplified signal to the RF signal processing circuit 52. The power amplifier 49 amplifies the RF signal provided by the RF signal processing circuit 52 and feeds the amplified signal to the antenna terminal 51 via the first duplexer transmitting filter 44, the second duplexer transmitting filter 46, and the switch 41 for transmission.

[0076] The RF signal processing circuit 52 in the RF communication device 50 performs signal processing on the RF reception signal provided from the antenna terminal 51 via the reception signal path, and feeds the reception signal generated by the signal processing. The RF signal processing circuit 52 performs signal processing on the transmission signal fed thereto, and feeds the RF transmission signal generated by the signal processing to the power amplifier 49.

[0077] The RF front-end circuit 40 further includes a first SAW filter 42 and a second SAW filter 43 . The first SAW filter 42 and the second SAW filter 43 are connected between the RF signal processing circuit 52 and the switch 41 without passing through the low noise amplifier 48 or the power amplifier 49 .

[0078] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A longitudinally coupled resonator type surface acoustic wave filter, characterized in that: include: Input terminals, output terminals, dual-mode acoustic wave filters and capacitors; The dual-mode acoustic wave filter comprises a first terminal, a second terminal and a ground terminal, wherein the first terminal is electrically connected to the input terminal, the second terminal is electrically connected to the output terminal, and the ground terminal is grounded; The capacitor is arranged between the ground terminal and the ground.

2. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The longitudinally coupled resonator type surface acoustic wave filter further includes a first grounding solder ball and a second grounding solder ball, the first grounding solder ball is grounded, and the second grounding solder ball is grounded; the capacitor includes a first capacitor; the grounding terminal includes a first grounding terminal and a second grounding terminal; The first capacitor is arranged between the first ground terminal and the first ground solder ball; Alternatively, the first capacitor is arranged between the first ground terminal and the second ground solder ball; Alternatively, the first capacitor is arranged between the second ground terminal and the first ground solder ball; Alternatively, the first capacitor is arranged between the second ground terminal and the second ground solder ball.

3. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The longitudinally coupled resonator type surface acoustic wave filter further comprises a first grounding solder ball and a second grounding solder ball, wherein the first grounding solder ball is grounded and the second grounding solder ball is grounded; the capacitor comprises a second capacitor and a third capacitor; the grounding terminal comprises a first grounding terminal and a second grounding terminal; The second capacitor is arranged between the first ground terminal and the first ground solder ball, and the third capacitor is arranged between the second ground terminal and the second ground solder ball; Alternatively, the second capacitor is arranged between the first ground terminal and the second ground solder ball, and the third capacitor is arranged between the second ground terminal and the first ground solder ball.

4. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The longitudinally coupled resonator type surface acoustic wave filter further includes an inductor, a first grounding solder ball and a second grounding solder ball, wherein the first grounding solder ball is grounded, and the second grounding solder ball is grounded; the capacitor includes a fourth capacitor; and the grounding terminal includes a first grounding terminal and a second grounding terminal; The inductor is arranged between the first ground terminal and the first ground solder ball, and the fourth capacitor is arranged between the second ground terminal and the second ground solder ball; Alternatively, the inductor is arranged between the first ground terminal and the second ground solder ball, and the fourth capacitor is arranged between the second ground terminal and the first ground solder ball.

5. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The capacitor includes an interdigital capacitor or a plate capacitor.

6. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The capacitance value C of the capacitor satisfies 0.1 pF≤C≤1 pF.

7. The longitudinally coupled resonator type surface acoustic wave filter according to claim 4, characterized in that: The inductance value L of the inductor satisfies 0.01nH≤L≤0.1nH.

8. The longitudinally coupled resonator type surface acoustic wave filter according to claim 1, wherein: The longitudinally coupled resonator type surface acoustic wave filter further comprises a series resonator and a parallel resonator; The series resonator and the dual-mode acoustic wave filter are connected in series between the input terminal and the output terminal; One end of the parallel resonator is electrically connected to one end of the series resonator or the first terminal or the second terminal, and the other end of the parallel resonator is grounded.

9. A surface acoustic wave multiplexer, characterized in that: comprising an antenna, at least one receiving unit and at least one transmitting unit; The antenna is communicatively connected to the receiving unit and the sending unit respectively; At least one of the receiving unit and the transmitting unit includes the longitudinally coupled resonator-type surface acoustic wave filter according to any one of claims 1 to 8.

10. A radio frequency front-end circuit, characterized in that: It comprises the surface acoustic wave multiplexer as claimed in claim 9.

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