A multiplexer, radio frequency module and electronic device

Abstract

This application provides a multiplexer, an RF module, and an electronic device, relating to the field of multiplexer technology. The multiplexer includes an antenna end, a transmitter filter, and a receiver filter. The transmitter filter includes multiple series resonators and multiple parallel resonators. The series resonators are connected in series between the first and second ends of the transmitter filter, and the parallel resonators are connected to one side of the series resonators. The first end of the transmitter filter is connected to the antenna end. The parallel resonator near the second end of the transmitter filter has an interdigital transducer with an electrode finger width less than a first preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitter filter is a first frequency. The first frequency is greater than the passband frequency of the transmitter filter and less than the stopband frequency of the transmitter filter, thereby enabling a reduction in the size of the transmitter filter without affecting its RF performance.

Description

Technical Field

[0001] This application relates to the field of multiplexer technology, and more particularly to a multiplexer, a radio frequency module, and an electronic device. Background Technology

[0002] Multiplexers are widely used devices in the radio frequency (RF) field and play a crucial role in wireless communication. However, with the development of wireless communication technology, the integration requirements for wireless communication devices are becoming increasingly stringent. Therefore, for multiplexers, how to reduce the size of the filters and thus the size of the multiplexer itself without affecting RF performance, in order to adapt to the trend of high integration in wireless communication devices, has become a key issue for those skilled in the art. Utility Model Content

[0003] In view of this, this application provides a multiplexer, an RF module, and an electronic device, as follows:

[0004] A multiplexer includes: an antenna end, a transmitter filter, and a receiver filter, wherein the antenna end is connected to the transmitter filter and the receiver filter respectively;

[0005] The transmitting filter includes multiple resonators, including series resonators and parallel resonators. The series resonators are connected in series between the first and second ends of the transmitting filter. The parallel resonators are connected to one side of the series resonators and are grounded through a grounding inductor. The first end of the transmitting filter is connected to the antenna end.

[0006] The resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate. The interdigital transducer includes electrode fingers arranged along a first direction, which is parallel to the mounting surface of the piezoelectric substrate.

[0007] Wherein, the parallel resonator near the second end of the transmitting filter, along the first direction, has an electrode finger width in the interdigital transducer that is a first width, which is less than a first preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitting filter is a first frequency, which is greater than the passband frequency of the transmitting filter and less than the stopband frequency of the transmitting filter.

[0008] Optionally, the parallel resonator near the second end of the transmitter filter, along the first direction, has a second width for the gap between adjacent electrode fingers in the interdigital transducer, the second width being less than a second preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitter filter is the first frequency.

[0009] Optionally, the number of electrode fingers in the interdigital transducer of the parallel resonator near the second end of the transmitting filter ranges from 60 to 80, including the endpoint values.

[0010] Optionally, the plurality of resonators includes four series resonators and four parallel resonators;

[0011] Along the direction from the first end to the second end of the transmitting filter, the four series resonators are sequentially a first series resonator, a second series resonator, a third series resonator, and a fourth series resonator, and the four parallel resonators are sequentially a first parallel resonator, a second parallel resonator, a third parallel resonator, and a fourth parallel resonator.

[0012] Wherein, along the first direction, in the interdigital transducer of the fourth parallel resonator, the width of the electrode fingers is a first width, the first width is less than the first preset value, and the resonant frequency of the fourth parallel resonator is the first frequency.

[0013] Optionally, the transmitter filter further includes a first matching structure, which includes a parallel capacitor;

[0014] A parallel capacitor is connected between the resonator near the first end of the transmitting filter and the first end, and the parallel capacitor is grounded;

[0015] A parallel capacitor is connected between the resonator and the second end near the second end of the transmitting filter, and the parallel capacitor is grounded.

[0016] Optionally, the first matching structure further includes a first series inductor;

[0017] A first series inductor is connected in series between the resonator near the first end of the transmitter filter and the first end, and the parallel capacitor is connected between the first series inductor and the resonator near the first end of the transmitter filter.

[0018] A first series inductor is connected in series between the resonator near the second end of the transmitter filter and the second end, and the parallel capacitor is connected between the first series inductor and the resonator near the second end of the transmitter filter.

[0019] Optionally, the transmitter filter further includes a second matching structure, which includes a parallel inductor;

[0020] A parallel inductor is connected between the resonator near the first end of the transmitting filter and the first end, and the parallel inductor is grounded;

[0021] A parallel inductor is connected between the resonator and the second end near the second end of the transmitting filter, and the parallel inductor is grounded.

[0022] Optionally, the transmitting filter further includes a third matching structure, wherein the third matching structure further includes a second series inductor;

[0023] A second series inductor is connected in series between the resonator near the first end of the transmitting filter and the first end;

[0024] The second series inductor is connected in series between the resonator near the second end of the transmitting filter and the second end.

[0025] A radio frequency module comprising any of the multiplexers described above.

[0026] An electronic device comprising the aforementioned radio frequency module.

[0027] Compared with related technologies, the beneficial effects of the technical solution in this application are as follows:

[0028] The multiplexer includes an antenna end, a transmitter filter, and a receiver filter. The transmitter filter includes multiple series resonators and multiple parallel resonators. The series resonators are connected in series between the first and second ends of the transmitter filter. The parallel resonators are connected to one side of the series resonators and are grounded through a grounding inductor. The first end of the transmitter filter is connected to the antenna end. The parallel resonator near the second end of the transmitter filter has an interdigital transducer with an electrode finger width of a first width, which is less than a first preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitter filter is a first frequency. This first frequency is greater than the passband frequency of the transmitter filter and less than the stopband frequency of the transmitter filter. This allows for a reduction in the size of the transmitter filter without affecting its RF performance, thereby reducing the size of the multiplexer and conforming to the trend of high integration. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0031] Figure 1 A schematic diagram of a multiplexer provided in this application;

[0032] Figure 2 A schematic diagram of the structure of a resonator in a multiplexer provided in this application;

[0033] Figure 3 for Figure 2 Enlarged view of the area marked with a dashed line at the midpoint;

[0034] Figure 4 and Figure 5 A performance comparison diagram of the transmitter filter in a multiplexer provided in this application;

[0035] Figure 6 A schematic diagram of another multiplexer provided in this application;

[0036] Figure 7 A schematic diagram of another type of multiplexer provided in this application;

[0037] Figure 8 A schematic diagram of another type of multiplexer provided in this application;

[0038] Figure 9 and Figure 10 A performance comparison diagram of the transmitter filter in another multiplexer provided in this application. Detailed Implementation

[0039] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] As described in the background section, how to reduce the size of filters and thus the size of multiplexers without affecting radio frequency performance, in order to adapt to the trend of high integration in wireless communication devices, has become a key issue for those skilled in the art.

[0042] Based on the above, this application provides a multiplexer, such as... Figure 1 As shown, Figure 1 This application provides a schematic diagram of a multiplexer, which includes an antenna Ant, a transmitter filter TX, and a receiver filter RX, wherein the antenna Ant is connected to both the transmitter filter TX and the receiver filter RX. Figure 1 In the diagram, R1 and R2 represent the two ends of the receiver filter RX, and T1 and T2 represent the two ends of the transmitter filter TX. Both the receiver filter RX and the transmitter filter TX are connected to the antenna Ant. The receiver filter RX generates a first output signal and transmits it downlink through the antenna Ant. The transmitter filter TX generates a second output signal and transmits it uplink through the antenna Ant. It should be understood that the receiver filter RX typically includes components such as multiple series resonators and multiple parallel resonators, but... Figure 1 The specific structure of the receiver filter RX is not shown in the figure.

[0043] Continue as Figure 1 As shown, the transmitter filter TX includes multiple resonators, including series resonators (e.g., Figure 1 (S1~S4) and parallel resonators (e.g.) Figure 1 The transmitter filter TX (P1~P4) can include multiple series resonators and multiple parallel resonators. The series resonators are connected in series between the first terminal T1 and the second terminal T2 of the transmitter filter TX. The parallel resonators are connected to one side of the series resonators and are grounded through a grounding inductor L1. The first terminal T1 of the transmitter filter TX is connected to the antenna terminal Ant, and one parallel resonator is connected between adjacent series resonators.

[0044] The resonator in this multiplexer is a surface acoustic wave resonator, specifically as follows: Figure 2 As shown, Figure 2This application provides a schematic diagram of the resonator structure in a multiplexer. The resonator of the multiplexer includes a piezoelectric substrate 100 and an interdigital transducer 200 located on the piezoelectric substrate 100. The interdigital transducer 200 includes electrode fingers 210 arranged along a first direction. The electrode fingers 210 include first electrode fingers 212 and second electrode fingers 214 arranged along the first direction. That is, the interdigital transducer 200 includes first electrode fingers 212 and second electrode fingers 214 alternately arranged along the first direction, which is parallel to the mounting surface of the piezoelectric substrate 100. It should be noted that, as Figure 2 As shown, the interdigital transducer 200 also includes a first busbar 201, a second busbar 202, and a reflective grid structure 203, wherein the first electrode finger 212 is electrically connected to the first busbar 201 and extends toward the second busbar 202, and the second electrode finger 214 is electrically connected to the second busbar 202 and extends toward the first busbar 201.

[0045] Based on the above, such as Figure 3 As shown, Figure 3 for Figure 2 The enlarged view of the area within the dashed box shows the parallel resonator P4, located near the second terminal T2 of the transmitter filter TX. Along the first direction, the width of the electrode fingers 210 in its interdigital transducer 200 is a first width W1, which is less than a first preset value. This ensures that the resonant frequency of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is a first frequency. This first frequency is greater than the passband frequency of the transmitter filter TX and less than the stopband frequency of the transmitter filter TX. In other words, the first frequency is greater than the frequencies within the passband of the transmitter filter TX and less than the frequencies within the stopband of the transmitter filter TX. This means the first frequency is located outside the passband of the transmitter filter TX and not within the stopband, and is also less than the stopband frequency, thus suppressing the stopband signal of the transmitter filter TX.

[0046] Since the resonant frequency of a surface acoustic wave (SAW) resonator is inversely proportional to the width of its electrode fingers, the resonator frequency can be adjusted by changing the width of the electrode fingers. In this application, in the transmitter filter TX of the multiplexer, the width of the electrode fingers 210 of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is smaller than a first preset value. That is, the width of the electrode fingers 210 can be smaller, thereby allowing for a larger resonant frequency of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX. By reducing the width of the electrode fingers 210 of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX, the resonant frequency of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is located outside the passband of the transmitter filter TX, not within the stopband, and is also lower than the stopband frequency. This allows the parallel resonator P4 near the second terminal T2 of the transmitter filter TX to suppress the stopband of the transmitter filter TX.

[0047] At the same time, according to Figure 4 and Figure 5 It can be seen that reducing the width of the electrode finger 210 of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX does not affect the RF performance of the transmitter filter TX. Furthermore, the stopband of the transmitter filter TX can be suppressed, thereby reducing the size of the transmitter filter TX without affecting its performance, and consequently reducing the size of the multiplexer, in line with the trend towards high integration.

[0048] Specifically, Figure 4 The red curve 1 represents the passband curve of the transmitter filter TX in the multiplexer described in this application, and the blue curve 2 represents the passband curve of the filter with the electrode finger width of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX not reduced. Figure 5 The red curve 3 in the middle is the stopband curve of the transmitter filter TX in the multiplexer described in this application, and the blue curve 4 is the stopband curve of the transmitter filter TX when the electrode finger width of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is not reduced. According to Figure 4 It can be seen that the insertion loss of the transmitter filter TX described in this application is basically the same in the passband range (880MHz~915MHz). Furthermore, according to... Figure 5 It is known that the transmitter filter TX described in this application has a stronger suppression effect on the stopband (925MHz~960MHz).

[0049] Furthermore, since the resonant frequency of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is outside the passband of the transmitter filter TX and also outside the stopband, and even lower than the stopband frequency, the parallel resonator P4 near the second terminal T2 of the transmitter filter TX can be equivalent to a capacitor within the passband of the transmitter filter TX. This allows the blocking effect of the transmitter filter TX to be shifted from a high-resistance region to a low-resistance region. This eliminates the need to increase the area of ​​each resonator, for example, by increasing the electrode index of each resonator, to achieve the same effect, thus further reducing the size of the transmitter filter TX.

[0050] In one embodiment of this application, such as Figure 3 As shown, the parallel resonator P4 near the second terminal T2 of the transmitter filter TX has a second width W2 in the interdigital transducer 200 along the first direction, where the gap between adjacent electrode fingers 210 is smaller than a second preset value, so that the resonant frequency of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is the first frequency. It should be noted that the width of the gap between adjacent electrode fingers 210 is the width of the gap between adjacent first electrode fingers 212 and second electrode fingers 214, i.e., the distance between adjacent first electrode fingers 212 and second electrode fingers 214.

[0051] Since the resonant frequency of a surface acoustic wave resonator is inversely proportional to the spacing between the electrode fingers, in the parallel resonator P4 near the second terminal T2 of the transmitter filter TX, the distance between adjacent electrode fingers 210 is less than a second preset value. This smaller distance allows for a reduction in resonator size while increasing the resonant frequency. This ensures that the first frequency is outside the passband of the transmitter filter TX, not falling into the stopband, and is also lower than the stopband frequency, thus suppressing the stopband of the transmitter filter TX. Therefore, in this multiplexer, the width of the electrode fingers 210 and the distance between adjacent electrode fingers 210 in the parallel resonator P4 near the second terminal T2 of the transmitter filter TX are both small, allowing for a further reduction in the size of the transmitter filter TX without affecting its RF performance.

[0052] In one embodiment of this application, the number of electrodes 210 in the interdigital transducer 200 of the parallel resonator P4 near the second terminal T2 of the transmitter filter TX can range from 60 to 80, including the endpoint values. Specifically, as previously known, the parallel resonator P4 near the second terminal T2 of the transmitter filter TX can be equivalent to a capacitor within the passband of the transmitter filter TX. Without increasing the number of electrodes 210, the blocking effect of the transmitter filter TX can be transformed from a high-resistance region to a low-resistance region. Therefore, the number of electrodes 210 in the parallel resonator P4 can be relatively small, for example, around 70. Since the number of electrodes 210 is typically around 250, the parallel resonator P4 near the second terminal T2 of the transmitter filter TX can significantly reduce the size of the transmitter filter TX.

[0053] In one embodiment of this application, such as Figure 1 As shown, the multiple resonators include four series resonators and four parallel resonators. Along the direction from the first terminal T1 to the second terminal T2 of the transmitter filter TX, the four series resonators are, in order, the first series resonator S1, the second series resonator S2, the third series resonator S3, and the fourth series resonator S4. Along the direction from the first terminal T1 to the second terminal T2 of the transmitter filter TX, the four parallel resonators are, in order, the first parallel resonator P1, the second parallel resonator P2, the third parallel resonator P3, and the fourth parallel resonator P4.

[0054] In this embodiment, along the first direction, in the interdigital transducer 200 of the fourth parallel resonator P4, the width of the electrode fingers 210 is a first width W1, which is less than a first preset value, and the resonant frequency of the fourth parallel resonator P4 is a first frequency. It should be noted that this embodiment is a specific embodiment of the multiplexer described in this application. This application does not limit the number of series and parallel resonators, but requires that the width of the electrode fingers 210 of the parallel resonator near the second terminal T2 of the transmitting filter TX is less than the first preset value, so that the resonant frequency of the parallel resonator is the first frequency.

[0055] It should be noted that if the width of the gap between adjacent electrode fingers 210 in the parallel resonator P4 near the second terminal T2 of the transmitter filter TX is the second width W2, then the width of the gap between adjacent electrode fingers 210 in the fourth parallel resonator P4 is the second width W2.

[0056] In one embodiment of this application, such as Figure 6 As shown, Figure 6 This application provides a schematic diagram of a multiplexer structure. The transmitter filter TX further includes a first matching structure, which includes a parallel capacitor C. PSpecifically, a parallel capacitor C is connected between the resonator at the first terminal T1 of the transmitter filter TX and the first terminal T1. P And the parallel capacitor C P Grounded. A parallel capacitor C is connected between the resonator at the second terminal T2 of the transmitter filter TX and the second terminal T2. P And the parallel capacitor C P Grounding. That is, parallel capacitors C are connected to both ends of the transmitter filter TX. P This can be based on the parallel capacitor C P Impedance transformation can be achieved without increasing the area of ​​each resonator, thereby reducing the size of the transmitter filter TX.

[0057] In one embodiment of this application, such as Figure 6 As shown, the first matching structure also includes a first series inductor L. S-1 A first series inductor L is connected in series between the resonator at the first terminal T1 of the transmitter filter TX and the first terminal T1. S-1 Parallel capacitor C P Connected to the first series inductor L S-1 Between the resonator at the first terminal T1 of the transmitter filter TX and the resonator at the second terminal T2 of the transmitter filter TX, a first series inductor L is connected in series between the resonator and the second terminal T2. S-1 Parallel capacitor C P Connected to the first series inductor L S-1 Between the resonator and the second terminal T2 of the transmitter filter TX. The difference between this embodiment and the previous embodiment is that the first matching structure in this embodiment includes a parallel capacitor C. P and the first series inductor L S-1 This allows for a greater degree of impedance transformation, thereby further reducing the size of the transmitter filter TX. Consequently, the area of ​​one or more resonators in the transmitter filter TX can be reduced to half its original size, resulting in a significant reduction in the area of ​​the transmitter filter TX.

[0058] In one embodiment of this application, such as Figure 7 As shown, Figure 7 This application provides a schematic diagram of a multiplexer structure. The transmitter filter TX further includes a second matching structure, which includes a parallel inductor L. P Specifically, a parallel inductor L is connected between the resonator at the first terminal T1 near the transmitter filter TX and the first terminal T1. P And parallel inductor L P Grounded. A parallel inductor L is connected between the resonator at the second terminal T2 of the transmitter filter TX and the second terminal T2. P And parallel inductor LP Grounding. That is, both ends of the transmitter filter TX are connected to a parallel inductor L. P Based on this parallel inductor L P Impedance transformation can be achieved without increasing the area of ​​each resonator, thereby reducing the size of the transmitter filter TX.

[0059] In one embodiment of this application, such as Figure 8 As shown, Figure 8 This application provides a schematic diagram of a multiplexer structure. The transmitter filter TX further includes a third matching structure, which includes a second series inductor L. S-2 Specifically, a second series inductor L is connected in series between the resonator at the first terminal T1 near the transmitter filter TX and the first terminal T1. S-2 A second series inductor L is connected in series between the resonator at the second terminal T2 of the transmitter filter TX and the second terminal T2. S-2 In other words, a second series inductor L is connected in series across both ends of the transmitter filter TX. S-2 It can be based on the second series inductor L S-2 Impedance transformation can be achieved without increasing the area of ​​each resonator, thereby reducing the size of the transmitter filter TX.

[0060] according to Figure 9 and Figure 10 It can be seen that the first matching structure, the second matching structure, and the third matching structure can reduce the size of the transmitter filter TX without affecting the RF performance of the transmitter filter TX. Specifically, Figure 9 In the middle, red curve 5 represents the passband curve of the transmitter filter TX with the first matching structure, and blue curve 6 represents the passband curve of the transmitter filter TX with the second or third matching structure. Figure 10 The red curve 7 represents the stopband curve of the transmitter filter TX with the first matching structure, while the blue curve 8 represents the stopband curve of the transmitter filter TX with the second or third matching structure. According to... Figure 9 It can be seen that the insertion loss of the transmitter filter TX is basically the same in the passband range (880MHz~915MHz). Figure 10 It can be seen that the suppressive power of the transmitter filter TX for the stopband (925MHz~960MHz) is basically the same.

[0061] Based on the above multiplexer, this application also provides a radio frequency module, which includes the multiplexer described in any of the above embodiments.

[0062] This application also provides an electronic device that includes the above-described radio frequency module.

[0063] In summary, this application provides a multiplexer, an RF module, and an electronic device. The multiplexer includes an antenna end, a transmitter filter, and a receiver filter. The transmitter filter includes multiple series resonators and multiple parallel resonators. The series resonators are connected in series between the first and second ends of the transmitter filter. The parallel resonators are connected to one side of the series resonators and grounded through a grounding inductor. The first end of the transmitter filter is connected to the antenna end. The parallel resonators near the second end of the transmitter filter have interdigitated transducers with a first width less than a first preset value, so that the resonant frequency of the parallel resonators near the second end of the transmitter filter is a first frequency. This first frequency is greater than the passband frequency of the transmitter filter and less than the stopband frequency of the transmitter filter, allowing for a reduction in the size of the transmitter filter without affecting its RF performance.

[0064] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0065] It should be noted that, in the description of this application, the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.

[0066] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multiplexer, characterized in that, include: The system includes an antenna terminal, a transmitter filter, and a receiver filter, wherein the antenna terminal is connected to the transmitter filter and the receiver filter, respectively. The transmitting filter includes multiple resonators, including series resonators and parallel resonators. The series resonators are connected in series between the first and second ends of the transmitting filter. The parallel resonators are connected to one side of the series resonators and are grounded through a grounding inductor. The first end of the transmitting filter is connected to the antenna end. The resonator includes a piezoelectric substrate and an interdigital transducer located on the piezoelectric substrate. The interdigital transducer includes electrode fingers arranged along a first direction, which is parallel to the mounting surface of the piezoelectric substrate. Wherein, the parallel resonator near the second end of the transmitting filter, along the first direction, has an electrode finger width in the interdigital transducer that is a first width, which is less than a first preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitting filter is a first frequency, which is greater than the passband frequency of the transmitting filter and less than the stopband frequency of the transmitting filter.

2. The multiplexer according to claim 1, characterized in that, The parallel resonator near the second end of the transmitter filter, along the first direction, has a second width in the gap between adjacent electrode fingers in the interdigital transducer, which is less than a second preset value, so that the resonant frequency of the parallel resonator near the second end of the transmitter filter is the first frequency.

3. The multiplexer of claim 1, wherein, The number of electrode fingers in the interdigital transducer of the parallel resonator near the second end of the transmitting filter ranges from 60 to 80, including the endpoint values.

4. The multiplexer of claim 1, wherein, The plurality of resonators includes four series resonators and four parallel resonators; Along the direction from the first end to the second end of the transmitting filter, the four series resonators are sequentially a first series resonator, a second series resonator, a third series resonator, and a fourth series resonator, and the four parallel resonators are sequentially a first parallel resonator, a second parallel resonator, a third parallel resonator, and a fourth parallel resonator. Wherein, along the first direction, in the interdigital transducer of the fourth parallel resonator, the width of the electrode fingers is a first width, the first width is less than the first preset value, and the resonant frequency of the fourth parallel resonator is the first frequency.

5. The multiplexer of claim 1, wherein, The transmitter filter further includes a first matching structure, which includes a parallel capacitor. A parallel capacitor is connected between the resonator near the first end of the transmitting filter and the first end, and the parallel capacitor is grounded; A parallel capacitor is connected between the resonator and the second end near the second end of the transmitting filter, and the parallel capacitor is grounded.

6. The multiplexer of claim 5, wherein, The first matching structure further includes a first series inductor; A first series inductor is connected in series between the resonator near the first end of the transmitter filter and the first end, and the parallel capacitor is connected between the first series inductor and the resonator near the first end of the transmitter filter. A first series inductor is connected in series between the resonator near the second end of the transmitter filter and the second end, and the parallel capacitor is connected between the first series inductor and the resonator near the second end of the transmitter filter.

7. The multiplexer of claim 1, wherein, The transmitter filter further includes a second matching structure, which includes a parallel inductor. A parallel inductor is connected between the resonator near the first end of the transmitting filter and the first end, and the parallel inductor is grounded; A parallel inductor is connected between the resonator and the second end near the second end of the transmitting filter, and the parallel inductor is grounded.

8. The multiplexer according to claim 1, characterized in that, The transmitter filter further includes a third matching structure, and the third matching structure further includes a second series inductor; A second series inductor is connected in series between the resonator near the first end of the transmitting filter and the first end; The second series inductor is connected in series between the resonator near the second end of the transmitting filter and the second end.

9. A radio frequency module, characterized in that, Includes the multiplexer as described in any one of claims 1-8.

10. An electronic device, characterized in that, Includes the radio frequency module as described in claim 9.

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