Duplexer and communication equipment

Abstract

The utility model provides a duplexer and a communication device, a transmitting filter is arranged between a common port and a first input / output end of the duplexer, the transmitting filter comprises a filter 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 common port, and the output end of the transmitting filter is connected to the first input / output end of the duplexer. The input end of the transmitting filter is connected to the first input / output end; a receiving filter is arranged between the common port and the second 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, the input end of the receiving filter is connected to the common port, and the output end of the receiving filter is connected to the second input and output end; the frequency of the film bulk acoustic resonator in the parallel resonance branch closest to the common port in the transmitting filter is set to be lower than the frequency of the film bulk acoustic resonators in other parallel resonance branches of the transmitting filter.

Description

Technical Field

[0001] The utility model relates to mobile communication, and particularly to a duplexer and a communication device related to mobile signal transmission. Background Art

[0002] With the development of mobile communication technology, mobile communication devices need to meet the communication requirements of different frequency bands and different systems, and the duplexer emerges as the times require. As a microwave device, the duplexer is used to allow the same antenna to transmit and receive signals simultaneously and selectively transmit signals of specific frequencies. With the rapid development of the fifth-generation communication technology, higher requirements are put forward for the volume and performance of the duplexer in communication devices.

[0003] The duplexer includes a transmit filter and a receive filter, and usually realizes the corresponding functions through filters composed of thin film bulk acoustic wave resonators. In theory, the transmit filter and the receive filter of the duplexer need to work simultaneously without interfering with each other. However, in actual applications, the duplexer will introduce nonlinear distortion, thereby affecting the signal quality. Summary of the Utility Model

[0004] The utility model has carefully designed the circuit structure of the duplexer and provides a duplexer that can improve nonlinear distortion.

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

[0006] According to one aspect of the utility model, a duplexer is provided, which includes: a common port, a first input / output terminal, a second input / output terminal, a transmit filter, and a receive filter; a transmit filter is arranged between the common port and the first input / output terminal. The transmit filter includes a filtering network composed of multiple series resonance branches containing thin film bulk acoustic wave resonators and multiple parallel resonance branches containing thin film bulk acoustic wave resonators. The output terminal of the transmit filter is connected to the common port, and the input terminal of the transmit filter is connected to the first input / output terminal; a receive filter is arranged between the common port and the second input / output terminal. The receive filter includes a filtering network composed of multiple series resonance branches containing thin film bulk acoustic wave resonators and multiple parallel resonance branches containing thin film bulk acoustic wave resonators. The input terminal of the receive filter is connected to the common port, and the output terminal of the receive filter is connected to the second input / output terminal; the frequency of the thin film bulk acoustic wave resonator in the parallel resonance branch closest to the common port in the transmit filter is set lower than the frequencies of the thin film bulk acoustic wave resonators in the other parallel resonance branches of the transmit filter.

[0007] Further, the frequency of the thin film bulk acoustic resonator in the parallel resonance branch closest to the common port of the transmit filter is set to be lower than the frequency of the passband of the transmit filter.

[0008] Further, a first matching circuit is further provided between the receive filter and the transmit filter and the common port; a second matching circuit is further provided in the receive filter and / or the transmit filter.

[0009] Further, the first matching unit is a matching unit presenting inductance.

[0010] Further, the transmit filter includes 4 series resonance branches and 5 parallel resonance branches. Each of the 4 series resonance branches of the transmit filter includes at least one thin film bulk acoustic resonator; the first parallel resonance branch of the transmit filter includes one thin film bulk acoustic resonator; each of the other parallel resonance branches of the transmit filter includes at least one thin film bulk acoustic resonator.

[0011] Further, the receive filter includes 4 series resonance branches and 4 parallel resonance branches. Each of the 4 series resonance branches of the receive filter includes at least one thin film bulk acoustic resonator, and each of the other parallel resonance branches of the receive filter includes at least one thin film bulk acoustic resonator.

[0012] Further, the first matching unit includes a T-shaped inductance unit. The first end of the T-shaped inductance unit is connected to the common port, the second end of the T-shaped inductance unit is connected to the output end of the transmit filter, and the third end of the T-shaped inductance unit is connected to the input end of the receive filter.

[0013] Further, the first series resonance branch of the transmit filter includes a sixth series resonator and a seventh series resonator connected in series, the second series resonance branch includes an eighth series resonator and a ninth series resonator connected in series, the third series resonance branch includes a tenth series resonator, and the fourth series resonance branch includes an eleventh series resonator; the first parallel resonance branch of the transmit filter includes a sixth parallel resonator, the second parallel resonance branch includes a seventh parallel resonator and an eighth parallel resonator connected in parallel, the third parallel resonance branch includes a ninth parallel resonator, the fourth parallel resonance branch includes a tenth parallel resonator, the fifth parallel resonance branch includes an eleventh parallel resonator, the sixth parallel resonator and the ninth parallel resonator are connected to ground through a common inductance L6, the seventh parallel resonator and the eighth parallel resonator are connected to ground through a common inductance L7, the tenth parallel resonator is connected to ground through an inductance L8, and the eleventh parallel resonator is connected to ground through an inductance L9; a matching inductance L10 is connected between the first input / output terminal and ground.

[0014] Further, the first series resonance branch of the receiving filter includes a first series resonator and a second series resonator connected in series, the second series resonance branch includes a third series resonator, the third series resonance branch includes a fourth series resonator, and the fourth series resonance branch includes a fifth series resonator; the first parallel resonance branch of the receiving filter includes a first parallel resonator and a second parallel resonator connected in parallel, the second parallel resonance branch includes a third parallel resonator, the third parallel resonance branch includes a fourth parallel resonator, and the fourth parallel resonance branch includes a fifth parallel resonator. The first parallel resonator and the second parallel resonator are connected to ground through a common inductance L1, the third parallel resonator is connected to ground through an inductance L2, and the fourth parallel resonator and the fifth parallel resonator are connected to ground through a common inductance L3; a matching inductance L4 is connected between the second input / output terminal and ground, and a matching inductance L5 is connected between the second input / output terminal and the output terminal of the receiving filter.

[0015] Further, the present utility model also discloses a communication device, including the duplexer of any one of the foregoing.

[0016] The beneficial effects of the present utility model are as follows: In the duplexer provided by the present utility model, by making the frequency of the thin film bulk acoustic wave resonator in the parallel resonance branch of the transmitting filter closest to the common port of the duplexer much lower than the frequencies of the thin film bulk acoustic wave resonators in other parallel resonance branches, the nonlinear distortion is improved and the communication quality is enhanced. Description of the Drawings

[0017] The following describes the specific content of the present utility model with reference to the drawings, which will help to more easily understand the above and other objects, features, and advantages of the present utility model. The drawings are only for showing the principle of the present utility model. In the drawings, the dimensions and relative positions of the units do not have to be drawn to scale.

[0018] Figure 1 Shows the circuit structure block diagram of the duplexer of the present utility model;

[0019] Figure 2 Shows a specific circuit structure embodiment of the duplexer provided by the present utility model. Detailed Embodiments

[0020] To make the above objects, features, and advantages of the present utility model more obvious and understandable, the following provides a detailed description of the specific embodiments of the present utility model with reference to the drawings, so that the above and other objects, features, and advantages of the present 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 showing the gist of the present utility model.

[0021] The terms and words used in the following description and claims are not limited to their written meanings, but are used solely by the inventor to enable a clear and consistent understanding of the present utility model. Therefore, it will be apparent to those skilled in the art that the following description of the various embodiments of the present utility model is for illustrative purposes only and not for the purpose of limiting the present utility model as defined by the appended claims and their equivalents.

[0022] It should be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a module" includes reference to one or more such modules. The advantages and features of the present utility model and the method of implementing the present utility model can be more easily understood by referring to the detailed description of the following embodiments and the drawings. However, the present utility model can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present utility model will be thorough and complete and will fully convey the concept of the present utility model to those skilled in the art.

[0023] Please refer to Figure 1 , Figure 1 which shows a circuit structure block diagram of a duplexer provided by the present utility model. The duplexer includes a common port A, a transmit filter 110, and a receive filter 100.

[0024] The common port A is an external port for transmitting and receiving signals through an antenna element (not shown in the figure); the input end of the transmit filter 110 is connected to a transmit port TP, and the transmit port TP is also referred to as a first input / output end. The output end of the transmit filter 110 is connected to the common port A; the input end of the receive filter 100 is connected to the common port A, and the output end of the receive filter 100 is connected to a receive port RP, and the receive port Rp is also referred to as a second input / output end.

[0025] Both the transmit filter 110 and the receive filter 100 may include M series branches SL1 - SL M , P parallel resonance branches PL1 - PL P , where M and P are natural numbers, and M and P may be the same value.

[0026] A matching circuit is connected between the common port A and each filter. Since the transmit filter 110 and the receive filter 100 exhibit capacitive characteristics, a first matching unit MC1 that exhibits inductive characteristics is provided to cancel the capacitive characteristics of each filter in the duplexer, so that the impedances of the transmit filter 110 and the receive filter 100 are matched and deterioration of the insertion loss is avoided. The first matching unit MC1 may be an inductor connected in parallel between the common port A and ground, or an inductor unit connected in series between the common port A and the transmit filter 110 and the receive filter 100.

[0027] Taking the transmitting filter 110 as an example, the setting methods of each series branch and parallel resonance branch will be described below. There are M series resonance branches and P parallel resonance branches in the transmitting filter 110, and both M and P are natural numbers. The M series resonance branches SL1 - SL M are sequentially arranged between the first matching unit MC1 and the transmitting port TP. Between the first matching unit MC1 and the series branch SL1, between adjacent series branches, and between the Mth series branch SL M and the transmitting port TP, there are connection nodes, that is, there are a total of (M + 1) connection nodes N1 - N M+1 .

[0028] One end of the Ith parallel resonance branch PL I is connected to the connection node N I+1 , and the other end of the Ith parallel resonance branch PL I is connected to the variable module MU. The variable module MU is selected from ground potential, common inductance, or a combination of the above options, where 1 ≤ I ≤ P. When the other end of the Ith parallel resonance branch PL I is connected to the variable module MU including a common inductance, the Ith parallel resonance branch PL I is connected to one end of the common inductance after being connected in parallel with at least another parallel resonance branch at least.

[0029] In an embodiment, as Figure 1 shown, series resonance units SZ1 - SZ M are respectively arranged on the series branches SL1 - SL M , and parallel resonance units PZ1 - PZ P are respectively arranged on the parallel resonance branches PL1 - PL P .

[0030] Furthermore, for the series resonance units SZ1 - SZ M and the parallel resonance units PZ1 - PZ P , they can be selected from one of the forms of a single resonance unit, a series connection of a resonance unit and an inductance element, and a parallel connection of a resonance unit and a capacitance element. Specifically, the resonance unit includes at least one resonator or multiple resonators. When the resonance unit includes multiple resonators, the multiple resonators are connected in series and / or in parallel.

[0031] Furthermore, when the series resonance units SZ1 - SZ M and the parallel resonance units PZ1 - PZ P are selected from the form of a series connection of a resonance unit and at least one inductance element, the inductance values of the inductance elements between different resonance units can be equal or unequal. When the series resonance units SZ1 - SZ Mand the parallel resonance units PZ1 - PZ P When selected in the form of a parallel connection of a resonance unit and a capacitive element, the capacitance values of the capacitive elements between different resonance units can be equal or unequal.

[0032] It can be understood that the setting methods of the series branches and parallel resonance branches of each filter of the receiving filter 100 can refer to the setting method of the transmitting filter 110, which will not be elaborated here.

[0033] In the duplexer of the present invention, for the connection methods of the series branches and parallel resonance branches of each filter, the parallel resonance branches in each filter can be connected to the common port prior to the series resonance branches, or the series resonance branches in each filter can be connected to the common port prior to the parallel resonance branches. In the present invention, it is preferred that the parallel resonance branches are connected to the common port prior to the series resonance branches. Further, the frequency of the thin - film bulk acoustic wave resonator in the parallel resonance branch closest to the common port A of the transmitting filter is set to be much lower than the frequency of the thin - film bulk acoustic wave resonators in other parallel resonance branches. Preferably, the frequency of the thin - film bulk acoustic wave resonator in the parallel resonance branch closest to the common port A of the transmitting filter is set to be lower than the frequency of the passband of the transmitting filter, thereby improving the nonlinear distortion of the duplexer and enhancing the communication quality.

[0034] In another embodiment, as Figure 1 shown, at least one of the receiving filter 100 and the transmitting filter 110 in the duplexer of the present invention may have a second matching unit MC2. Specifically, the second matching unit MC2 can be disposed at the transmitting port TP of the transmitting filter 110 and / or at the receiving port RP of the receiving filter 100.

[0035] Further, when the second matching unit MC2 is disposed at the transmitting port TP of the transmitting filter 110, it can be serially disposed between the node N M+1 and the transmitting port TP of the transmitting filter 110, or the second matching unit MC2 can be parallely disposed between the node N M+1 of the transmitting filter 110 and the ground potential. At this time, the second matching unit MC2 is used to match the impedance of the transmitting filter 110 itself to avoid signal reflection and signal loss. The second matching unit MC2 can be various series - parallel combinations of capacitors and / or inductors.

[0036] It can be understood that when the second matching unit MC2 is disposed at the receiving port RP of the receiving filter 100, the method and function are the same as those when the second matching unit MC2 is disposed at the transmitting port TP of the transmitting filter 110, which will not be elaborated here.

[0037] Please refer to Figure 2 , Figure 2Shows a schematic diagram of a specific circuit structure of the duplexer provided by the present utility model.

[0038] As Figure 2 shown, the duplexer may include a common port A, a transmit port TP, a receive port RP, a first matching unit, a transmit filter 110, and a receive filter 100.

[0039] Specifically, the common port A is an external port for transmitting and receiving radio waves through an antenna element (not shown in the figure);

[0040] The first matching unit includes a T-shaped inductance unit disposed between the common port A and the output end of the transmit filter 110 and the input end of the receive filter 100. The first end of the T-shaped inductance unit is connected to the common port, the second end of the T-shaped inductance unit is connected to the output end of the transmit filter, and the third end of the T-shaped inductance unit is connected to the input end of the receive filter. More specifically, the first end of the inductance Lm1 in the T-shaped inductance unit is connected to the common port A, the second end of the inductance Lm1 is connected to the first end of the inductance Lm2 and the first end of the inductance Lm3, the second end of the inductance Lm2 is connected to the input end of the receive filter 100, and the second end of the inductance Lm3 is connected to the output end of the transmit filter 110.

[0041] The transmit filter 110 is disposed between the first matching unit and the transmit port TP. As Figure 2 shown, the transmit filter 110 includes 4 series resonance branches and 5 parallel resonance branches. The 4 series resonance branches are sequentially connected in series between the first matching unit and the transmit port TP. There are connection nodes between the first matching unit and the first series resonance branch, between the 4 series resonance branches, and between the fourth series resonance branch and the transmit port TP. As Figure 2 shown, there are a total of 5 connection nodes N7-N11 between the first matching unit and the transmit port TP.

[0042] Series resonance units are provided on each series resonance branch. As Figure 2 described, the series resonance unit on the first series resonance branch is composed of the resonator s6 and the resonator s7; the series resonance unit on the second series resonance branch is composed of the resonator s8 and the resonator s9; the series resonance unit on the third series resonance branch is composed of the resonator s10; the series resonance unit on the fourth series resonance branch is composed of the resonator s11.

[0043] Parallel resonance units are provided on each parallel resonance branch. As Figure 2Among the five parallel resonant branches shown in the figure, the resonant unit on the first parallel resonant branch is composed of the thin film bulk acoustic wave resonator p6; the resonant unit on the second parallel resonant branch is composed of the parallel connection of the thin film bulk acoustic wave resonator p7 and the thin film bulk acoustic wave resonator p8; the resonant unit on the third parallel resonant branch is composed of the thin film bulk acoustic wave resonator p9; the resonant unit on the fourth parallel resonant branch is composed of the thin film bulk acoustic wave resonator p10; the resonant unit on the fifth parallel resonant branch is composed of the thin film bulk acoustic wave resonator p11. The resonant frequency of the thin film bulk acoustic wave resonator p6 is set to be much lower than the resonant frequencies of the thin film bulk acoustic wave resonators p7, p8, p9, p10, and p11. Preferably, the resonant frequency of the thin film bulk acoustic wave resonator p6 in the parallel resonant branch of the transmit filter is set to be lower than the frequency of the passband of the transmit filter.

[0044] Further, the first end of the resonator p6 is connected to the connection node N7, the second end of the resonator p6 is connected to the first end of the common inductance L6, and the second end of the common inductance L6 is connected to the ground. The first ends of the resonator p7 and the resonator p8 are connected to the connection node N8, the second ends of the resonator p7 and the resonator p8 are connected to the first end of the inductance L7, and the second end of the inductance L7 is connected to the ground. The first end of the resonator p9 is connected to the connection node N9, and the second end of the resonator p9 is connected to the first end of the common inductance L6. The first end of the resonator p10 is connected to the connection node N10, and the second end of the resonator p10 is connected to the first end of the inductance L8. The second end of the inductance L8 is connected to the ground. The first end of the resonator p11 is connected to the connection node N11, the second end of the resonator p11 is connected to the first end of the inductance L9, and the second end of the inductance L9 is connected to the ground.

[0045] Further, an inductance L10 can be connected between the connection node N11 and the ground to achieve impedance matching of the first input / output port B of the transmit filter 110.

[0046] The receive filter 100 is disposed between the first matching unit and the receive port RP, as Figure 2 shown, the receive filter 100 includes four series resonant branches and four parallel resonant branches, and the four series resonant branches are sequentially connected in series between the first matching unit and the receive port RP. There are connection nodes between the first matching unit and the first series resonant branch of the receive filter 100, between the four series resonant branches of the receive filter 100, and between the fourth series resonant branch of the receive filter 100 and the transmit port TP, as Figure 1 shown, there are a total of six connection nodes N1 - N6 between the common port A and the transmit port TP.

[0047] Series resonant units are disposed on each series resonant branch of the receive filter 100. As Figure 2As described in [reference], the series resonance unit on the first series resonance branch of the receiving filter 100 is composed of the serially connected resonators s1 and s2; the series resonance unit on the second series resonance branch is composed of the resonator s3; the series resonance unit on the third series resonance branch is composed of the resonator s4; and the series resonance unit on the fourth series resonance branch is composed of the resonator s5.

[0048] Parallel resonance units are provided on each parallel resonance branch. As Figure 2 In the 4 parallel resonance branches shown in [reference], the parallel resonance unit on the first parallel resonance branch is composed of the parallel resonators p1 and p2; the series resonance unit on the second parallel resonance branch is composed of the resonator p3; the series resonance unit on the third parallel resonance branch is composed of the resonator p4; and the series resonance unit on the fourth parallel resonance branch is composed of the resonator p5.

[0049] The first end of the resonator p1 is connected to the connection node N2, the first end of the resonator p2 is connected to the connection node N2, the second end of the resonator p1 is connected to the second end of the resonator p2 and then connected to the first end of the inductor L1, and the first end of the inductor L1 is connected to the ground. The first end of the resonator p3 is connected to the connection node N3, the second end of the resonator p3 is connected to the first end of the inductor L2, and the second end of the inductor L2 is connected to the ground. The first end of the resonator p4 is connected to the connection node N4, the first end of the resonator p5 is connected to the connection node N5, the second end of the resonator p4 is connected to the second end of the resonator p5 and then connected to the first end of the common inductor L3, and the second end of the common inductor L3 is connected to the ground.

[0050] Furthermore, an inductor L4 can be connected between the receiving port RP and the ground, and an inductor L5 can be connected between the connection node N6 and the receiving port RP to achieve impedance matching of the receiving port RP of the receiving filter 100.

[0051] In summary, in the duplexer provided by the present invention, in the transmitting filter 110 and the receiving filter 100, the frequency of the thin film bulk acoustic wave resonator p6 in the parallel resonance branch closest to the common port A of the transmitting filter 110 is set to be much lower than the frequencies of the thin film bulk acoustic wave resonators in other parallel resonance branches. Preferably, the frequency of the thin film bulk acoustic wave resonator p6 in the parallel resonance branch closest to the common port A of the transmitting filter is set to be lower than the frequency of the passband of the transmitting filter, thereby improving the nonlinear distortion of the duplexer and improving the communication quality.

[0052] The duplexer in the present invention can be used in the fields of portable communication devices such as mobile phones, personal digital assistants (PDAs), personal wearable devices, and electronic game devices.

[0053] Although the technology has been described and illustrated with respect to one or more embodiments, modifications and / or changes 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 that performs the specified function of the described component (e.g., functionally equivalent), even if not structurally equivalent to the disclosed structure that performs the functions in the exemplary embodiments described herein, unless otherwise specified. Additionally, 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 one or more other embodiments as may be desired and advantageous for any given or particular application. Further, to the extent that the detailed description or claims use the terms "comprises," "comprising," "has," "having," "contains," or variants thereof, such terms are intended to be inclusive in a manner similar to the term "including."

[0054] Numerous specific details are set forth in the foregoing description in order to provide a thorough understanding of the present utility model. However, the above description is only a preferred embodiment of the present utility model, and the present utility model can be implemented in many other ways different from those described herein. Therefore, the present utility model is not limited by the specific embodiments disclosed above. At the same time, any person skilled in the art can, without departing from the scope of the technical solution of the present utility model, make many possible changes and modifications to the technical solution of the present utility model by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes. All simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the content of the technical solution of the present utility model still fall within the scope of the protection of the technical solution of the present utility model.

Claims

1. A duplexer, characterized in that, Comprising: A common port, a first input / output terminal, a second input / output terminal, a transmit filter, and a receive filter; A transmit filter is provided between the common port and the first input / output terminal. The transmit filter includes a filter network composed of multiple series resonance branches containing thin film bulk acoustic wave resonators and multiple parallel resonance branches containing thin film bulk acoustic wave resonators. The output terminal of the transmit filter is connected to the common port, and the input terminal of the transmit filter is connected to the first input / output terminal; A receive filter is provided between the common port and the second input / output terminal. The receive filter includes a filter network composed of multiple series resonance branches containing thin film bulk acoustic wave resonators and multiple parallel resonance branches containing thin film bulk acoustic wave resonators. The input terminal of the receive filter is connected to the common port, and the output terminal of the receive filter is connected to the second input / output terminal; The frequency of the thin film bulk acoustic wave resonator in the parallel resonance branch closest to the common port in the transmit filter is set lower than the frequency of the thin film bulk acoustic wave resonators in the other parallel resonance branches of the transmit filter.

2. The duplexer according to claim 1, characterized in that: The frequency of the thin film bulk acoustic wave resonator in the parallel resonance branch closest to the common port of the transmit filter is set lower than the frequency of the passband of the transmit filter.

3. The duplexer according to claim 1 or 2, wherein: A first matching circuit is further provided between the receive filter and the transmit filter and the common port; a second matching circuit is further provided in the receive filter and / or the transmit filter.

4. The duplexer according to claim 3, characterized in that: The first matching unit is a matching unit presenting inductance.

5. The duplexer according to claim 4, wherein: The transmit filter includes 4 series resonance branches and 5 parallel resonance branches. Each of the 4 series resonance branches of the transmit filter includes at least one thin film bulk acoustic wave resonator; the first parallel resonance branch of the transmit filter includes one thin film bulk acoustic wave resonator; each of the other parallel resonance branches of the transmit filter includes at least one thin film bulk acoustic wave resonator.

6. The duplexer according to claim 5, wherein: The receive filter includes 4 series resonance branches and 4 parallel resonance branches. Each of the 4 series resonance branches of the receive filter includes at least one thin film bulk acoustic wave resonator, and each of the other parallel resonance branches of the receive filter includes at least one thin film bulk acoustic wave resonator.

7. The duplexer according to claim 6, wherein: The first matching unit includes a T-shaped inductance unit. The first end of the T-shaped inductance unit is connected to the common port, the second end of the T-shaped inductance unit is connected to the output terminal of the transmit filter, and the third end of the T-shaped inductance unit is connected to the input terminal of the receive filter.

8. The duplexer according to claim 7, wherein: The first series resonance branch of the transmit filter includes a sixth series resonator and a seventh series resonator connected in series, the second series resonance branch includes an eighth series resonator and a ninth series resonator connected in series, the third series resonance branch includes a tenth series resonator, and the fourth series resonance branch includes an eleventh series resonator; the first parallel resonance branch of the transmit filter includes a sixth parallel resonator, the second parallel resonance branch includes a seventh parallel resonator and an eighth parallel resonator connected in parallel, the third parallel resonance branch includes a ninth parallel resonator, the fourth parallel resonance branch includes a tenth parallel resonator, the fifth parallel resonance branch includes an eleventh parallel resonator, the sixth parallel resonator and the ninth parallel resonator are connected to ground through a common inductor L6, the seventh parallel resonator and the eighth parallel resonator are connected to ground through a common inductor L7, the tenth parallel resonator is connected to ground through an inductor L8, and the eleventh parallel resonator is connected to ground through an inductor L9; a matching inductor L10 is connected between the first input / output terminal and ground.

9. The duplexer according to claim 8, wherein: The first series resonance branch of the receive filter includes a first series resonator and a second series resonator connected in series, the second series resonance branch includes a third series resonator, the third series resonance branch includes a fourth series resonator, and the fourth series resonance branch includes a fifth series resonator; the first parallel resonance branch of the receive filter includes a first parallel resonator and a second parallel resonator connected in parallel, the second parallel resonance branch includes a third parallel resonator, the third parallel resonance branch includes a fourth parallel resonator, the fourth parallel resonance branch includes a fifth parallel resonator, the first parallel resonator and the second parallel resonator are connected to ground through a common inductor L1, the third parallel resonator is connected to ground through an inductor L2, and the fourth parallel resonator and the fifth parallel resonator are connected to ground through a common inductor L3; a matching inductor L4 is connected between the second input / output terminal and ground, and a matching inductor L5 is connected between the second input / output terminal and the output terminal of the receive filter.

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

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