Duplexer and communication equipment

Abstract

The utility model provides a duplexer and communication equipment. The duplexer comprises an antenna end, a first input / output end, a second input / output end, a first matching inductor, a transmitting filter and a receiving filter, the transmitting filter comprises a filtering network formed by a plurality of series resonance branches and a plurality of parallel resonance branches, the output end of the transmitting filter is connected to the antenna end, and the input end of the transmitting filter is connected to the first input and output end; the receiving filter comprises a filter network formed by a plurality of series resonance branches and a plurality of parallel resonance branches; one end of the first matching inductor is connected to the output end of the transmitting filter, the other end of the first matching inductor is connected in series with the input end of the receiving filter, and the output end of the receiving filter is connected with the second input / output end; inductors connected to the ground are arranged in the multiple parallel resonance branches of the receiving filter, and the first matching inductor and the inductors connected to the ground in at least one parallel resonance branch of the receiving filter form mutual coupling.

Description

Technical Field

[0001] The utility model relates to mobile communication, in particular to a duplexer and communication equipment involving mobile signal transmission. Background Art

[0002] With the development of mobile communication technology, mobile communication equipment needs to meet the communication requirements of different frequency bands and different standards, and duplexers came into being. As a microwave device, duplexers are used to allow the same antenna to send and receive signals at the same time, and selectively transmit signals of specific frequencies. With the rapid development of the fifth generation of communication technology, communication equipment has put forward higher requirements on the size and performance of duplexers.

[0003] The current duplexer includes a transmitting filter and a receiving filter, and the corresponding functions are often realized through a filter composed of a resonator. If the passbands of the transmitting filter Tx and the receiving filter Rx are close to each other, that is, when the relative stopband width is less than or equal to 1.5%, a series inductor is usually used to match the receiving filter Rx and the antenna. Since the inductance of the series inductor is relatively large, generally greater than or equal to 4nH, the size of the duplexer is large, which is not conducive to the miniaturization of the device. In order to meet the requirements of chip miniaturization, it has become an urgent problem to reduce the series inductance value of the impedance matching between the receiving filter Rx and the antenna to adapt to the miniaturization of the chip. Utility Model Content

[0004] The utility model has carefully designed the circuit structure of the duplexer and successfully developed a duplexer which can solve the above technical problems.

[0005] A brief overview of the present invention will be given below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0006] According to one aspect of the utility model, a duplexer is provided, comprising: an antenna end, a first input-output end, a second input-output end, a first matching inductor, a transmitting filter and a receiving filter; the transmitting filter comprises a filter network composed of a plurality of series resonant branches and a plurality of parallel resonant branches, the output end of the transmitting filter is connected to the antenna end, and the input end of the transmitting filter is connected to the first input-output end; the receiving filter comprises a filter network composed of a plurality of series resonant branches and a plurality of parallel resonant branches; one end of the first matching inductor is connected to the output end of the transmitting filter, the other end of the first matching inductor is connected in series with the input end of the receiving filter, and the output end of the receiving filter is connected to the second input-output end; the plurality of parallel resonant branches of the receiving filter have an inductor connected to the ground, and the first matching inductor forms mutual coupling with the inductor connected to the ground in at least one parallel resonant branch of the receiving filter.

[0007] Furthermore, the first matching inductor forms mutual coupling with a first inductor connected to the ground and closest to the antenna end in the receiving filter.

[0008] Furthermore, the duplexer is arranged on a substrate including multiple metal layers, the first matching inductor and the first inductor are arranged on different metal layers of the substrate, and the projection area of ​​the winding of the first matching inductor on the metal layer of the substrate overlaps with the projection area of ​​the winding of the first inductor on the metal layer of the substrate.

[0009] Furthermore, a winding direction of the first matching inductor on the metal layer of the substrate is the same as a winding direction of the first inductor on the metal layer of the substrate.

[0010] Furthermore, the duplexer is arranged on a substrate including multiple metal layers, the first matching inductor and the first inductor are arranged on the same metal layer of the substrate, and the spacing between the windings of the first matching inductor and the windings of the first inductor is the minimum value of the substrate wiring rule.

[0011] Furthermore, a winding direction of the first matching inductor on the metal layer of the substrate is the same as a winding direction of the first inductor on the metal layer of the substrate.

[0012] Furthermore, when a plurality of parallel resonant branches in the receiving filter have inductors connected to the ground, mutual coupling is formed between the inductors connected to the ground in any two parallel resonant branches.

[0013] Furthermore, the transmitting filter includes 4 series resonant branches and 4 parallel resonant branches, and each of the 4 series resonant branches of the transmitting filter includes a thin film bulk acoustic wave resonator; the first parallel resonant branch of the transmitting filter includes a first thin film bulk acoustic wave resonator and an inductor L1 connected in series; the second parallel resonant branch of the transmitting filter includes a second thin film bulk acoustic wave resonator and an inductor L2 connected in series; the third parallel resonant branch of the transmitting filter includes a third thin film bulk acoustic wave resonator; the fourth parallel resonant branch of the transmitting filter includes a fourth thin film bulk acoustic wave resonator, and the third thin film bulk acoustic wave resonator and the fourth thin film bulk acoustic wave resonator are connected to the ground through a common inductor L3; and a second matching inductor is connected between the first input and output terminals and the ground.

[0014] Furthermore, the receiving filter includes 4 series resonant branches and 5 parallel resonant branches, and each of the 4 series resonant branches of the receiving filter includes a thin film bulk acoustic wave resonator; the first parallel resonant branch of the receiving filter includes a fifth thin film bulk acoustic wave resonator; the second parallel resonant branch includes a sixth thin film bulk acoustic wave resonator; the fifth thin film bulk acoustic wave resonator and the sixth thin film bulk acoustic wave resonator are connected to the ground through an inductor L5; the third parallel resonant branch includes a seventh thin film bulk acoustic wave resonator and an inductor L6 connected in series, the fourth parallel resonant branch includes an eighth thin film bulk acoustic wave resonator, the fifth parallel resonant branch includes a ninth thin film bulk acoustic wave resonator, and the eighth thin film bulk acoustic wave resonator and the ninth thin film bulk acoustic wave resonator are connected to the ground through an inductor L7; a third matching inductor is connected between the second input and output terminals and the ground.

[0015] Furthermore, the utility model also discloses a communication device, comprising any of the aforementioned duplexers.

[0016] The beneficial effects of the utility model are as follows: the duplexer provided in the utility model can realize impedance matching between the receiving filter and the antenna in the duplexer circuit when the passbands of the transmitting filter Tx and the receiving filter Rx are close to each other, and can effectively reduce the value of the matching inductance, which is convenient for miniaturization of the device, and at the same time can avoid significant degradation of suppression and isolation, thereby improving communication quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specific contents of the utility model are described below with reference to the accompanying drawings, which will help to more easily understand the above and other purposes, features and advantages of the utility model. The accompanying drawings are only for illustrating the principles of the utility model. The sizes and relative positions of the units in the accompanying drawings do not need to be drawn in proportion.

[0018] Figure 1 It is a circuit structure diagram of the utility model duplexer;

[0019] Figure 2a-2cThe transmission characteristics of the duplexer provided by the utility model are shown;

[0020] Figure 2d The figure shows the isolation characteristic of the duplexer provided by the utility model. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the specific implementation of the utility model is described in detail below in conjunction with the accompanying drawings, so that the above-mentioned and other purposes, features and advantages of the utility model will be clearer. The same reference numerals in all the drawings indicate the same parts. The drawings are not deliberately drawn to scale, and the focus is on illustrating the main purpose of the utility model.

[0022] The terms and words used in the following description and claims are not limited to the written meanings, but are only used by the inventor so that the present invention can be clearly and consistently understood. Therefore, it is obvious to those skilled in the art that the following description of various embodiments of the present invention is provided for the purpose of illustration only, and not for the purpose of limiting the present invention as defined by the attached claims and their equivalents.

[0023] It should be understood that the singular forms of "a", "an", and "the" include plural objects unless the context clearly indicates otherwise. Thus, for example, reference to a "module" includes reference to one or more such modules. The advantages and features of the present invention and methods of implementing the present invention can be more easily understood by reference to the detailed description and drawings of the embodiments below. However, the present invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present invention will be thorough and complete and will fully convey the concepts of the present invention to those skilled in the art.

[0024] Figure 1 This is the circuit structure diagram of the utility model duplexer. Figure 1 As shown, the duplexer may include an antenna terminal A, a first input-output terminal B, a second input-output terminal C, a matching inductor Lmc, a transmit filter Tx, and a receive filter Rx.

[0025] Specifically, the antenna terminal A is an external port for sending and receiving radio waves through an antenna element (not shown in the figure);

[0026] The transmit filter Tx is arranged between the antenna terminal A and the first input-output terminal B. The transmit filter Tx includes a filter network consisting of a plurality of series resonant branches and a plurality of parallel resonant branches. The specific number of branches can be determined according to specific design requirements and should not be used as a specific limitation of the present disclosure. For example, Figure 1As shown in , the transmit filter Tx includes 4 series resonant branches and 4 parallel resonant branches, and the 4 series resonant branches are sequentially arranged in series between the antenna terminal A and the first input-output terminal B. There are connection nodes between the antenna terminal A and the first series resonant branch, between the 4 series resonant branches, and between the 4th series resonant branch and the first input-output terminal B, as shown in FIG. Figure 1 As shown in FIG. 1 , there are five connection nodes N1 - N5 between the antenna terminal A and the first input / output terminal B.

[0027] A series resonance unit is provided on each series resonance branch. It is understood that the series resonance unit further includes a resonator or multiple resonators. When the series resonance unit includes multiple resonators, the multiple resonators are connected in series and / or in parallel. It is understood that the parallel resonance unit can also be a combination of a resonator and an inductor and / or a capacitor. The resonator in this embodiment is preferably a thin film bulk acoustic wave resonator.

[0028] For example, Figure 1 As described in the figure, the series resonance unit on the first series resonance branch is composed of resonator s1; the series resonance unit on the second series resonance branch is composed of resonator s2; the series resonance unit on the third series resonance branch is composed of resonator s3; and the series resonance unit on the fourth series resonance branch is composed of resonator s4.

[0029] A parallel resonance unit is provided on each parallel resonance branch. It is understandable that the parallel resonance unit further includes a resonator or a plurality of resonators. When the parallel resonance unit includes a plurality of resonators, the plurality of resonators are connected in series and / or in parallel. The resonator in this embodiment is an electronic component that can generate a resonant frequency, has the characteristics of stability and good anti-interference performance, and is widely used in various electronic products. The resonator can be a thin film cavity body acoustic wave resonator or a solid assembly resonator or a surface wave resonator, etc. It is understandable that the parallel resonance unit can also be a combination of a resonator and an inductor and / or a capacitor. The resonator in the utility model is preferably a thin film cavity body acoustic wave resonator.

[0030] For example, Figure 1 In the four parallel resonant branches shown in the figure, the parallel resonant unit on the first parallel resonant branch is composed of resonator p1; the series resonant unit on the second parallel resonant branch is composed of resonator p2; the series resonant unit on the third parallel resonant branch is composed of resonator p3; and the series resonant unit on the fourth parallel resonant branch is composed of resonator p4.

[0031] One end of the resonator p1 is connected to the connection node N2, and the other end of the resonator p1 is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the ground. One end of the resonator p2 is connected to the connection node N3, and the other end of the resonator p2 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the ground. One end of the resonator p3 is connected to the connection node N4, one end of the resonator p4 is connected to the connection node N5, and the other end of the resonator p3 is connected to the other end of the resonator p4 and then connected to one end of the common inductor L3, and the other end of the common inductor L3 is connected to the ground.

[0032] Furthermore, an inductor L4 may be connected between the first input / output terminal B and the ground to achieve impedance matching of the first input / output port B of the transmit filter Tx.

[0033] The receiving filter Rx is arranged between the antenna terminal A and the second input-output terminal C. The receiving filter Rx includes a filtering network consisting of a plurality of series branches and a plurality of parallel branches. The specific number of series branches and parallel branches can be determined according to specific design requirements, and should not be used as a specific limitation of the present disclosure.

[0034] For example, Figure 1 As shown in , the receiving filter Rx includes 4 series resonant branches and 4 parallel resonant branches, and the 4 series resonant branches are sequentially arranged in series between the antenna terminal A and the second input-output terminal C. There are connection nodes between the antenna terminal A and the first series resonant branch of the receiving filter Rx, between the 4 series resonant branches of the receiving filter Rx, and between the 4th series resonant branch of the receiving filter Rx and the first input-output terminal B, as shown in FIG. Figure 1 As shown in FIG. 1 , there are 6 connection nodes N1 , N6 - N10 between the antenna terminal A and the first input / output terminal B.

[0035] A series resonance unit is provided on each series resonance branch of the receiving filter Rx. It is understandable that the series resonance unit further includes a resonator or a plurality of resonators. When the series resonance unit includes a plurality of resonators, the plurality of resonators are connected in series and / or in parallel. The resonator in this embodiment is an electronic component that can generate a resonant frequency, has the characteristics of stability and good anti-interference performance, and is widely used in various electronic products. The resonator can be a thin film cavity acoustic wave resonator or a solid assembly resonator or a surface wave resonator, etc. It is understandable that the series resonance unit can also be a combination of a resonator and an inductor and / or a capacitor. The resonator in the utility model is preferably a thin film cavity acoustic wave resonator.

[0036] For example, Figure 1As described in the figure, the series resonance unit on the first series resonance branch is composed of resonator s5; the series resonance unit on the second series resonance branch is composed of resonator s6; the series resonance unit on the third series resonance branch is composed of resonator s7; and the series resonance unit on the fourth series resonance branch is composed of resonator s8.

[0037] A parallel resonance unit is provided on each parallel resonance branch. It is understood that the parallel resonance unit further includes a resonator or multiple resonators. When the parallel resonance unit includes multiple resonators, the multiple resonators are connected in series and / or in parallel. It is understood that the parallel resonance unit can also be a combination of a resonator and an inductor and / or a capacitor. The resonator in this embodiment is preferably a thin film bulk acoustic wave resonator.

[0038] For example, Figure 1 Among the five parallel resonant branches shown in the figure, the parallel resonant unit on the first parallel resonant branch is composed of resonator p5; the series resonant unit on the second parallel resonant branch is composed of resonator p6; the series resonant unit on the third parallel resonant branch is composed of resonator p7; the series resonant unit on the fourth parallel resonant branch is composed of resonator p8; and the series resonant unit on the fifth parallel resonant branch is composed of resonator p9.

[0039] One end of the resonator p5 is connected to the connection node N6, one end of the resonator p6 is connected to the connection node N7, the other end of the resonator p5 is connected to the other end of the resonator p6 and then connected to one end of the inductor L5, and the other end of the inductor L5 is connected to the ground. One end of the resonator p7 is connected to the connection node N8, the other end of the resonator p7 is connected to one end of the inductor L6, and the other end of the inductor L6 is connected to the ground. One end of the resonator p8 is connected to the connection node N9, one end of the resonator p9 is connected to the connection node N10, the other end of the resonator p8 is connected to the other end of the resonator p9 and then connected to one end of the common inductor L7, and the other end of the common inductor L7 is connected to the ground.

[0040] Furthermore, an inductor L8 may be connected between the second input / output terminal C and the ground to achieve impedance matching of the receiving filter Rx second input / output port C. The matching inductor Lmc is connected in series between the connection node N1 and the connection node N6 to achieve impedance matching of the transmitting filter Tx and the receiving filter Rx.

[0041] It should be noted that Figure 1 The transmitting filter Tx and receiving filter Rx in the embodiment are merely exemplary descriptions, and the present invention does not further define them. Figure 1In addition to the structure shown, those skilled in the art will appreciate that both the transmit filter Tx and the receive filter Rx may include more series resonant branches and / or parallel resonant branches, for example, 6, 8 or more series resonant branches and parallel resonant branches may be used, and of course conversely the number of series resonant branches and / or parallel resonant branches may be reduced, for example, only 3 series resonant branches and 3 parallel resonant branches may be used to form a resonant filter network.

[0042] Further, when the series resonant unit and the parallel resonant unit are selected from the form of a resonator and at least an inductor connected in parallel, the inductance values ​​of the inductors between different resonant units may be equal or unequal. When the series resonant unit and the parallel resonant unit are selected from the form of a resonance and a capacitor connected in parallel, the capacitance values ​​of the capacitors between different resonant units may be equal or unequal.

[0043] Furthermore, the BAW resonators in the parallel resonant branches of the transmit filter Tx and the receive filter Rx can be grounded after being connected in series with the inductor, or the parallel branches can be grounded through a shared inductor. When the parallel branches are grounded through a shared inductor, it can be any combination of parallel branches and is not limited to specific parallel branches and the number of parallel branches.

[0044] Furthermore, the inductor Lmc in the present invention is coupled with at least one of the inductor L5, the inductor L6 or the shared inductor L7 in the receiving filter Rx. According to the design requirements of the specific duplexer, corresponding coupling adjustment can also be performed. The present invention can reduce the value of the inductor Lmc by about 10-15% through the above coupling design, so that when the passbands of the transmitting filter Tx and the receiving filter Rx of the duplexer are close to each other, the impedance matching between the receiving filter in the duplexer circuit and the antenna can be achieved, and the value of the matching inductor can be effectively reduced, which is convenient for miniaturization of the device.

[0045] Preferably, the inductor Lmc in the present invention is coupled with the inductor L5 in the receiving filter Rx, and the inductor L5 is the first inductor connected in parallel to the ground and closest to the antenna terminal A. Since the first inductor is closest to the antenna terminal A, the substantial degradation of the suppression and isolation of the receiving filter Rx can be effectively avoided.

[0046] Furthermore, mutual coupling may be formed between any two of the inductors L5 , L6 , and L7 in the receiving filter Rx.

[0047] More preferably, when coupling is achieved between the inductor Lmc and the inductor L5 in the receiving filter Rx, in order to increase the coupling coefficient between the two, in the duplexer packaging structure, the duplexer chip can be mounted on a substrate having multiple metal layers and dielectric layers spaced apart, and the inductor Lmc and the inductor L5 can be arranged on different metal layers of the substrate, and the projection area of ​​the winding of the inductor Lmc on the metal layer of the substrate and the winding of the inductor L5 on the metal layer of the substrate can overlap, and the winding direction of the inductor Lmc can be the same as the winding direction of the inductor L5.

[0048] It is understandable that the winding of the inductor Lmc and the winding of the inductor L5 can also be arranged on the same metal layer of the substrate. At this time, in order to increase the coupling coefficient between the two, the spacing between the two windings can be reduced to the minimum value of the substrate wiring rule, and the winding directions of the two can be set to the same direction.

[0049] See also Figure 2a-2c , Figure 2a-2c The transmission characteristics of the duplexer provided by the utility model are shown in FIG. Figure 2a-2c As shown in the figure, the waveforms in the passband of each filter in the duplexer are flat, and the return loss is about 15dB, which shows that the passband matching effect is good. Figure 2d , Figure 2d The figure shows the isolation characteristics of the duplexer provided by the utility model. Figure 2d As shown, the isolation of the duplexer is about 60dB, which shows that the isolation effect is good.

[0050] In summary, when the passbands of the transmitting filter Tx and the receiving filter Rx are close to each other, the duplexer provided by the utility model can conveniently realize the impedance matching between the receiving filter and the antenna in the duplexer circuit, and can effectively reduce the value of the matching inductor, thereby facilitating the miniaturization of the device and avoiding the significant degradation of the suppression and isolation of the receiving filter Rx.

[0051] Although the technology has been illustrated and described with respect to one or more embodiments, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In particular, with respect to the various functions performed by the above-described components or structures (assemblies, devices, circuits, systems, etc.), the terms used to describe such components (including references to "means") are intended to correspond to any component or structure (e.g., functionally equivalent) that performs the specified function of the described component, even if not structurally equivalent to the disclosed structure that performs the function in the example embodiments described herein, unless otherwise specified. In addition, although a particular feature may have been disclosed with respect to one of several embodiments, such a feature may be combined with one or more other features in other embodiments as may be desired and advantageous for any given or particular application. In addition, to the extent that the terms "comprising," "including," "having," "having," "containing," or variations thereof are used in the detailed description or claims, such terms are intended to be inclusive in a manner similar to the term "comprising."

[0052] In the above description, many specific details are described to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited by the specific implementation disclosed above. At the same time, any person familiar with the technical field can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A duplexer, characterized in that: include: An antenna terminal, a first input-output terminal, a second input-output terminal, a first matching inductor, a transmitting filter, and a receiving filter; The transmitting filter comprises a filter network composed of a plurality of series resonant branches and a plurality of parallel resonant branches, the output end of the transmitting filter is connected to the antenna end, and the input end of the transmitting filter is connected to the first input-output end; The receiving filter includes a filter network composed of a plurality of series resonant branches and a plurality of parallel resonant branches; One end of the first matching inductor is connected to the output end of the transmitting filter, the other end of the first matching inductor is connected in series with the input end of the receiving filter, and the output end of the receiving filter is connected to the second input-output end; The multiple parallel resonant branches of the receiving filter have inductors connected to the ground, and the first matching inductor forms mutual coupling with the inductor connected to the ground in at least one parallel resonant branch of the receiving filter.

2. The duplexer according to claim 1, wherein: The first matching inductor forms mutual coupling with a first inductor connected to the ground and closest to the antenna end in the receiving filter.

3. The duplexer according to claim 2, characterized in that: The duplexer is arranged on a substrate including multiple metal layers, the first matching inductor and the first inductor are arranged on different metal layers of the substrate, and the projection area of ​​the winding of the first matching inductor on the metal layer of the substrate overlaps with the projection area of ​​the winding of the first inductor on the metal layer of the substrate.

4. The duplexer according to claim 3, characterized in that: The winding direction of the first matching inductor on the metal layer of the substrate is the same as the winding direction of the first inductor on the metal layer of the substrate.

5. The duplexer according to claim 2, wherein: The duplexer is arranged on a substrate including multiple metal layers, the first matching inductor and the first inductor are arranged on the same metal layer of the substrate, and the spacing between the windings of the first matching inductor and the windings of the first inductor is the minimum value of the substrate wiring rule.

6. The duplexer according to claim 5, characterized in that: The winding direction of the first matching inductor on the metal layer of the substrate is the same as the winding direction of the first inductor on the metal layer of the substrate.

7. The duplexer according to claim 2, characterized in that: When a plurality of parallel resonant branches in a receiving filter have inductors connected to the ground, mutual coupling is formed between the inductors connected to the ground in any two parallel resonant branches.

8. The duplexer according to any one of claims 1 to 7, characterized in that: The transmitting filter comprises four series resonant branches and four parallel resonant branches, each of the four series resonant branches of the transmitting filter comprises a thin film bulk acoustic wave resonator; the first parallel resonant branch of the transmitting filter comprises a first thin film bulk acoustic wave resonator and an inductor L1 connected in series; the second parallel resonant branch of the transmitting filter comprises a second thin film bulk acoustic wave resonator and an inductor L2 connected in series; the third parallel resonant branch of the transmitting filter comprises a third thin film bulk acoustic wave resonator; the fourth parallel resonant branch of the transmitting filter comprises a fourth thin film bulk acoustic wave resonator, the third thin film bulk acoustic wave resonator and the fourth thin film bulk acoustic wave resonator are connected to the ground via a common inductor L3; and a second matching inductor is connected between the first input and output terminals and the ground.

9. The duplexer according to claim 8, characterized in that: The receiving filter comprises four series resonant branches and five parallel resonant branches, each of the four series resonant branches of the receiving filter comprises a thin film bulk acoustic wave resonator; the first parallel resonant branch of the receiving filter comprises a fifth thin film bulk acoustic wave resonator; The second parallel resonant branch includes a sixth thin film bulk acoustic resonator; The fifth FBAR and the sixth FBAR are connected to the ground via the inductor L5; The third parallel resonant branch includes a seventh film bulk acoustic resonator and an inductor L6 connected in series, the fourth parallel resonant branch includes an eighth film bulk acoustic resonator, the fifth parallel resonant branch includes a ninth film bulk acoustic resonator, the eighth film bulk acoustic resonator and the ninth film bulk acoustic resonator are connected to the ground via the inductor L7; a third matching inductor is connected between the second input and output terminals and the ground.

10. A communication device, characterized in that: A duplexer comprising the duplexer according to any one of claims 1 to 9.

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