Multiplexer and communication device

Abstract

The application discloses a multiplexer and a communication device, and belongs to the technical field of filters. The multiplexer comprises an antenna terminal, a first filter connected with the antenna terminal, and a second filter connected with the antenna terminal, the frequency of a first passband of the first filter is smaller than the frequency of a second passband of the second filter, and the first filter comprises multiple-stage series-parallel resonators. A resonant peak value corresponding to a frequency of a first-stage series-parallel resonator closest to the antenna terminal in the first filter is formed through electromagnetic coupling, and the frequency is located on a low-frequency side of the second passband. By adjusting the structural parameters of the first-stage series-parallel resonator closest to the antenna terminal in the first filter, an additional attenuation effect is formed on a low-frequency side of the second filter, so that the near-end suppression performance of the second filter is effectively improved without affecting the original performance of the filter.

Description

Technical Field

[0001] This application belongs to the field of filter technology, and in particular relates to a multiplexer and communication equipment. Background Technology

[0002] As a key component of passive microwave devices, filters have an absolute impact on the performance and size of the entire microwave transceiver system. With the trend towards high integration and miniaturization in RF front-ends, the requirements for the performance, miniaturization, and multi-path integration of surface acoustic wave (SAW) filters in next-generation RF front-end modules (Phase 8L-PAMiD) are constantly increasing. Multiplexers, due to their single antenna port, have multiple signal paths with small frequency spacing between adjacent paths, often resulting in insufficient near-end suppression and crosstalk. This not only degrades their own performance but also leads to a decrease in the receiving sensitivity of the entire microwave transceiver system, including issues such as adjacent channel leakage, signal interference in dynamic spectrum sharing scenarios, and reduced spectrum utilization.

[0003] Traditional surface acoustic wave (SAW) filters employ several methods to address near-end suppression. One approach involves cascading capacitors onto the resonator to increase passband rectangularity. However, this introduces noise at the far end, and the capacitance value is susceptible to shifts due to manufacturing precision, impacting passband performance. Another method is to increase the number of series and parallel stages in the filter topology to enhance near-end suppression. While this improves out-of-band near-end suppression, it also worsens passband insertion loss, making it impossible to simultaneously meet the requirements of low in-band insertion loss and high near-end suppression. A third approach sacrifices passband insertion loss to improve near-end suppression. All of these methods ultimately degrade the filter's original performance. Summary of the Invention

[0004] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a multiplexer and communication device that, by adjusting the structural parameters of the first-stage series-parallel resonator closest to the antenna terminal in the first filter, creates an additional attenuation effect on the near-end signal on the low-frequency side of the second filter, thereby effectively improving the near-end suppression performance of the second filter without affecting the original performance of the filter.

[0005] In a first aspect, this application provides a multiplexer, including an antenna terminal, a first filter connected to the antenna terminal, and a second filter connected to the antenna terminal. The frequency of a first passband of the first filter is lower than the frequency of a second passband of the second filter. The first filter includes a multi-stage series-parallel resonator. The frequency corresponding to the resonance peak formed by the electromagnetic coupling of the first-stage series-parallel resonator closest to the antenna terminal in the first filter is located at the near end of the low-frequency side of the second passband.

[0006] According to one embodiment of this application, the period of at least one resonator in the first-stage series-parallel resonator is less than a first standard value; And / or, the number of fingers of at least one of the resonators in the first-stage series-parallel resonators is less than the second standard value.

[0007] According to one embodiment of this application, the deviation between the period and the first standard value is 3%-5%; And / or, refers to a deviation of 40%-55% between the number of entries and the second standard value.

[0008] According to one embodiment of this application, the first-stage series-parallel resonator includes a first series resonator and a first parallel resonator, the first series resonator being connected to an antenna terminal, and the first parallel resonator being connected to either end of the first series resonator. The first-stage series-parallel resonator satisfies at least one of the following: The period of the first series resonator is 3%-5% smaller than the period of the smallest electrode among the other series resonators in the first filter; The number of fingers in the first series resonator is 40%-55% smaller than the minimum number of fingers in the other series resonators in the first filter; The period of the first parallel resonator is 3%-5% smaller than the minimum electrode period of the other parallel resonators in the first filter; The number of fingers in the first parallel resonator is 40%-55% smaller than the minimum number of fingers in the other parallel resonators in the first filter.

[0009] According to one embodiment of this application, the insertion loss of the second filter near the low-frequency side is less than or equal to -3dB.

[0010] According to one embodiment of this application, the frequency interval between the first passband and the second passband is 30MHz-50MHz.

[0011] According to one embodiment of this application, the frequency of the first passband is 1805MHz-1880MHz, the frequency of the second passband is 1920MHz-1980MHz, and the frequency corresponding to the resonant peak is between 1900MHz-1910MHz.

[0012] According to one embodiment of this application, the multiplexer further includes a third filter connected to the antenna terminal and a fourth filter connected to the antenna terminal; The third filter is used to implement the transmission channel of the Band 3 band, the first filter is used to implement the reception channel of the Band 3 band, the second filter is used to implement the transmission channel of the Band 1 band, and the fourth filter is used to implement the reception channel of the Band 1 band.

[0013] According to one embodiment of this application, the first filter and the second filter have a first resonator circuit topology, and the third filter and the fourth filter have a second resonator circuit topology. The number of resonators in the first resonator circuit topology is different from the number of resonators in the second resonator circuit topology.

[0014] Secondly, this application provides a communication device, including the multiplexer as described above.

[0015] According to the multiplexer and communication equipment of this application, by adjusting the structural parameters of the first-stage series-parallel resonator closest to the antenna terminal in the first filter, a specific electromagnetic coupling effect is generated and transmitted to the second filter through the antenna terminal. A resonant peak is generated at the near end of the low-frequency side of the passband of the second filter, which forms an additional attenuation effect on the near end signal of the low-frequency side of the second filter, thereby effectively improving the near end suppression performance of the second filter without affecting the original performance of the filter.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is one of the structural schematic diagrams of the multiplexer provided in the embodiments of this application; Figure 2 This is a second schematic diagram of the structure of the multiplexer provided in the embodiments of this application; Figure 3 This is a schematic diagram of the passbands of frequency band A and frequency band B provided in the embodiments of this application; Figure 4 This is one of the passband diagrams of frequency band B after the resonator structure optimization provided in the embodiments of this application; Figure 5 This is the second schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application; Figure 6 This is the third schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application; Figure 7 This is the fourth schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application.

[0018] Figure label: Antenna terminal ANT, first filter 100, first-stage series-parallel resonator 110, second filter 200, third filter 300, fourth filter 400, signal terminal 500. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] It should be understood that when a component or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other components or layers, it may be directly on, adjacent to, connected to, or coupled to other components or layers, or there may be intervening components or layers. Conversely, when a component is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other components or layers, there are no intervening components or layers.

[0021] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] Reference Figure 1 , Figure 1This is one of the structural schematic diagrams of a multiplexer provided in an embodiment of this application. In this embodiment, the multiplexer includes an antenna terminal ANT, a first filter 100 connected to the antenna terminal ANT, and a second filter 200 connected to the antenna terminal ANT. The frequency of the first passband of the first filter 100 is lower than the frequency of the second passband of the second filter 200. The first filter 100 includes multiple stages of series-parallel resonators. The frequency corresponding to the resonance peak formed by the electromagnetic coupling of the first-stage series-parallel resonator 110 closest to the antenna terminal ANT in the first filter 100 is located near the low-frequency side of the second passband.

[0024] The antenna terminal ANT is used to connect to an external antenna, through which the multiplexer transmits and receives radio frequency signals. The first filter can be used to transmit signals, and the second filter can be used to receive signals; or the first filter can be used to receive signals, and the second filter can be used to transmit signals; or both can be used to transmit signals; or both can be used to receive signals.

[0025] The first and second filters can be surface acoustic wave (SAW) filters. SAW filters utilize the propagation characteristics of surface acoustic waves on a piezoelectric substrate to achieve frequency selection. SAW filters mainly consist of interdigital transducers (IDTs) and a reflective grating structure, achieving filtering through the mutual conversion between electrical signals and surface acoustic waves. The electrode pitch and the number of fingers of the interdigital transducers are key parameters affecting the resonant characteristics of the resonator.

[0026] The first and second filters can be trapezoidal filters, including series resonators (SR) and parallel resonators (PR). One end of the first and second filters can be connected to signal terminal 500. The resonator connected in series between signal terminal 500 and antenna terminal ANT is a series resonator, and one end of the parallel resonator is connected to the signal line between signal terminal 500 and antenna terminal ANT, while the other end is grounded.

[0027] A series-parallel resonator refers to a resonator network composed of series resonators and parallel resonators. The first-stage series-parallel resonator 110 refers to the resonator network closest to the antenna terminal ANT. It may include at least one series resonator and at least one parallel resonator.

[0028] As an example, such as Figure 1As shown, the first-stage series-parallel resonator 110 includes a series resonator and a parallel resonator. The first end of the series resonator is connected to the antenna terminal ANT, the first end of the parallel resonator is connected to the second end of the series resonator, and the second end of the parallel resonator is grounded.

[0029] In other examples, the first end of the parallel resonator in the above examples may also be connected to the first end of the series resonator. Alternatively, multiple series resonators may be connected in series between the antenna terminal ANT and the first end of the parallel resonator. Or, the first ends of multiple parallel resonators may be connected between the first end of the series resonator and the antenna terminal ANT.

[0030] The series and parallel resonators within the first-stage series-parallel resonator 110 form a resonant network, and its structural parameters affect the impedance characteristics of this resonant network. Furthermore, since each channel is connected to the same antenna terminal ANT, the electromagnetic coupling of the first-stage series-parallel resonator 110 can be transmitted to other filters through the antenna terminal ANT. In this embodiment, the first-stage series-parallel resonator 110 can be designed with structural parameters such that the frequency corresponding to its resonant peak is located near the low-frequency side of the second passband, thereby improving the near-end suppression performance of the second filter.

[0031] Understandably, the resonator structure in the high-frequency channel is more compact, and the first filter with a lower frequency first passband has more adjustment space than the second filter with a higher frequency second passband. Therefore, the near-end rejection performance of the second filter can be improved by adjusting the structure of the first-stage series-parallel resonator 110 in the first filter 100, which is easily implemented.

[0032] In this embodiment, the multiplexer adjusts the structural parameters of the first-stage series-parallel resonator 110, which is closest to the antenna terminal in the first filter, to generate a specific electromagnetic coupling effect. This effect is then transmitted to the second filter through the antenna terminal, generating a resonant peak at the near end of the low-frequency side of the second filter's passband. This creates an additional attenuation effect on the near-end signal of the low-frequency side of the second filter, thereby effectively improving the near-end suppression performance of the second filter without affecting its original performance.

[0033] In some embodiments, the period of at least one of the resonators in the first-stage series-parallel resonators 110 is less than a first standard value; And / or, the number of fingers of at least one of the resonators in the first-stage series-parallel resonators 110 is less than the second standard value.

[0034] The period refers to the distance between the centers of adjacent electrode fingers in the interdigital transducer of a resonator. Adjusting the period is a key parameter that can be used to adjust the resonant frequency of the resonator. The number of fingers refers to the number of pairs of electrode fingers in the interdigital transducer of a resonator. Adjusting the number of fingers can be used to adjust the quality factor and coupling strength of the resonator.

[0035] The first standard value can be the standard period of the first-stage series-parallel resonator 110 when the first filter achieves the first passband. By reducing the period of the first-stage series-parallel resonator 110, the resonant frequency of the first-stage resonant network can be shifted towards higher frequencies, thereby suppressing the near-end signal on the low-frequency side of the second filter.

[0036] The second standard value can be the standard number of fingers of the first-stage series-parallel resonator 110 when the first filter achieves the first passband. By reducing the number of fingers of the first-stage series-parallel resonator 110, the electromagnetic coupling peak of the first-stage resonant network can be made sharper, thereby suppressing the near-end signal on the low-frequency side of the second filter.

[0037] In this embodiment, the first-stage series-parallel resonator 110 includes at least one series resonator and at least one parallel resonator. The series resonator can simultaneously reduce the period and the number of fingers, or reduce one of them. The parallel resonator can also simultaneously reduce the period and the number of fingers, or reduce one of them. The series resonator and the parallel resonator can jointly reduce the same structural parameters, or reduce different structural parameters, which refer to the period and the number of fingers.

[0038] In some embodiments, the deviation between the period and the first standard value is 3%-5%; and / or, the deviation between the number of bars and the second standard value is 40%-55%.

[0039] A period that is 3%-5% smaller than the first standard value ensures the resonant frequency offset while avoiding excessive offset that could degrade the passband performance of the first filter. A finger count that is 40%-55% smaller than the second standard value optimizes the sharpness of the coupling peak, effectively improving the near-end suppression of the second filter.

[0040] In some embodiments, the first-stage series-parallel resonator 110 includes a first series resonator and a first parallel resonator, the first series resonator being connected to an antenna terminal, and the first parallel resonator being connected to either end of the first series resonator.

[0041] Continue to refer to Figure 1As an example, the first-stage series-parallel resonator 110 includes a series resonator and a parallel resonator, the series resonator serving as a first series resonator and the parallel resonator serving as a first parallel resonator. A first terminal of the first series resonator is connected to an antenna terminal, a first terminal of the first parallel resonator is connected to a second terminal of the first series resonator, and a second terminal of the second parallel resonator is grounded. Of course, in other examples, the first terminal of the first parallel resonator may also be connected to the first terminal of the first series resonator.

[0042] In this example, the first-stage series-parallel resonator 110 satisfies at least one of the following: the period of the first series resonator is 3%-5% smaller than the minimum electrode period of the remaining series resonators in the first filter; the number of fingers of the first series resonator is 40%-55% smaller than the minimum number of fingers of the remaining series resonators in the first filter; the period of the first parallel resonator is 3%-5% smaller than the minimum electrode period of the remaining parallel resonators in the first filter; and the number of fingers of the first parallel resonator is 40%-55% smaller than the minimum number of fingers of the remaining parallel resonators in the first filter.

[0043] For example, the first series resonator simultaneously reduces both the period and the number of fingers; or the first parallel resonator simultaneously reduces both the period and the number of fingers; or both the first series resonator and the first parallel resonator reduce both the period and the number of fingers.

[0044] In some embodiments, the insertion loss of the second filter near the low-frequency side is less than or equal to -3 dB.

[0045] In this embodiment, the first-stage series-parallel resonator 110 is designed with structural parameters to form near-end suppression and a high attenuation region near the low-frequency side of the second passband. The insertion loss of the second filter near the low-frequency side can be -3dB, -4dB, or -7dB, etc., to improve the filtering performance of the second filter.

[0046] In some embodiments, the frequency interval between the first passband and the second passband is 30MHz-50MHz.

[0047] The first passband is smaller than the second passband. The frequency interval refers to the frequency difference between the upper frequency limit of the first passband and the lower frequency limit of the second passband. When the frequency interval between the two passbands is 30MHz-50MHz, the near-end suppression problem is particularly prominent due to the small frequency interval. This embodiment is applied to multiplexers with small frequency intervals. By adjusting the parameters of the first-stage series-parallel resonator 110 of the first filter 100, a sharp coupling peak can be generated near the passband of the second filter 200, effectively filling the suppression blind zone between adjacent frequency bands.

[0048] In some embodiments, the frequency of the first passband is 1805MHz-1880MHz, the frequency of the second passband is 1920MHz-1980MHz, and the frequency corresponding to the resonant peak is between 1900MHz-1910MHz.

[0049] The first passband, 1805MHz-1880MHz, corresponds to the receive frequency range of the Band 3 band as defined by the 3GPP (3rd Generation Partnership Project). The second passband, 1920MHz-1980MHz, corresponds to the transmit frequency range of the Band 1 band. The resonant peak frequency of 1900MHz-1910MHz is located near the low-frequency side of the Band 1 passband and is a critical region for near-end suppression. This embodiment generates a sharp coupling peak in the 1900MHz-1910MHz range by adjusting the first-stage series-parallel resonator 110 of the first filter 100, effectively filling the suppression blind zone between the Band 3 and Band 1 bands.

[0050] Reference Figure 2 , Figure 2 This is a second schematic diagram of the multiplexer provided in the embodiments of this application. In this embodiment, the multiplexer further includes a third filter 300 connected to the antenna terminal ANT and a fourth filter 400 connected to the antenna terminal ANT; the third filter 300 is used to implement the transmission channel of the Band 3 frequency band, the first filter 100 is used to implement the reception channel of the Band 3 frequency band, the second filter 200 is used to implement the transmission channel of the Band 1 frequency band, and the fourth filter 400 is used to implement the reception channel of the Band 1 frequency band.

[0051] In this embodiment, the multiplexer is a quadruple structure, containing four filter paths: Band3 receive channel (B3RX), Band3 transmit channel (B3TX), Band1 transmit channel (B1TX), and Band1 receive channel (B1RX). The four filters share the same antenna terminal, enabling simultaneous transmission of signals across four frequency bands.

[0052] The first passband frequency of the first filter 100 can be 1805MHz-1880MHz, the second passband frequency of the second filter 200 can be 1920MHz-1980MHz, the third passband frequency of the third filter 300 can be 1710MHz-1785MHz, and the fourth passband frequency of the fourth filter 400 can be 2110MHz-2170MHz.

[0053] In this embodiment, by optimizing the structural parameters of the first-stage series-parallel resonator 110 in the Band3 receiving channel, the near-end rejection of the Band1 transmitting channel is improved, thereby enhancing signal quality. Since the TX typically requires higher transmit power, optimizing the resonator structure in the RX channel compared to the TX channel reduces the impact on the multiplexer's performance.

[0054] In some embodiments, the first filter 100 and the second filter 200 have a first resonator circuit topology, and the third filter 300 and the fourth filter 400 have a second resonator circuit topology. The number of resonators in the first resonator circuit topology is different from the number of resonators in the second resonator circuit topology.

[0055] Resonator circuit topology refers to the connection topology of series resonators and parallel resonators in a filter. As an example, such as... Figure 2 As shown, the first filter 100 and the second filter 200 adopt the same circuit topology. B3TX and B1RX are located on the lower and upper sides of the entire multiplexer spectrum, respectively. They adopt the same high-order ladder topology and improve wideband suppression by cascading multiple resonators.

[0056] The third filter 300 and the fourth filter 400 use the same circuit topology. The two channels have similar frequencies and use the same short-chain topology to achieve near-end suppression. At the same time, by adjusting the first-stage series-parallel resonator 110 of B3RX, the near-end suppression of B1TX is improved. For example, the insertion loss of 1900MHz-1910MHz can be made less than or equal to -3dB.

[0057] like Figure 2 As shown, the number of resonators in the first resonator circuit topology can be less than the number of resonators in the second resonator circuit topology. Of course, in other examples, the number of resonators in the first resonator circuit topology can also be greater than the number of resonators in the second resonator circuit topology.

[0058] Reference Figure 3 , Figure 3 This is a schematic diagram of the passbands of frequency bands A and B provided in an embodiment of this application. Frequency band A is 1805MHz-1880MHz, corresponding to channel B3RX; frequency band B is 1920MHz-1980MHz, corresponding to channel B1TX. Figure 1 Taking the topology shown as an example, in Figure 1 The figure shows that when the first-stage series-parallel resonator 110 in the B3RX channel adopts standard structural parameters (i.e., unoptimized), the minimum suppression in the 1900MHz-1910MHz region of frequency band B is -2.5dB at 1910MHz.

[0059] Reference Figure 4 , Figure 4 This is one of the passband schematic diagrams for frequency band B after the resonator structure optimization provided in the embodiments of this application. Continuing with... Figure 1 Taking the topology shown as an example, the structural parameters of the first-stage series-parallel resonator 110 are optimized so that the period of the first parallel resonator in the first filter 100 is 4% smaller than the minimum period of all parallel resonators in the path. As can be seen from the figure, the minimum suppression in the 1900MHz-1910MHz region of frequency band B is about -3dB at 1910MHz.

[0060] Reference Figure 5 , Figure 5 This is the second schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application. Continuing with... Figure 1 Taking the topology shown as an example, the structural parameters of the first-stage series-parallel resonator 110 are optimized so that the period of the first series resonator in the first filter 100 is 4% smaller than the minimum period of all series resonators in the path. As can be seen from the figure, the minimum suppression in the 1900MHz-1910MHz region of frequency band B is -4dB.

[0061] Reference Figure 6 , Figure 6 This is the third schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application. Continuing with... Figure 1 Taking the illustrated topology as an example, the structural parameters of the first-stage series-parallel resonator 110 are optimized so that the period of the first parallel resonator in the first filter 100 is 4% smaller than the minimum period of all parallel resonators in the path, and the number of fingers of the first parallel resonator is 45% less than the minimum number of fingers of all parallel resonators in the path. As can be seen from the figure, the minimum suppression in the 1900MHz-1910MHz region of frequency band B is approximately -5dB at 1910MHz.

[0062] Reference Figure 7 , Figure 7 This is the fourth schematic diagram of the passband of frequency band B after the resonator structure optimization provided in the embodiments of this application. Continuing with... Figure 1 Taking the illustrated topology as an example, the structural parameters of the first-stage series-parallel resonator 110 are optimized so that the period of the first series resonator in the first filter 100 is 4% smaller than the minimum period of all series resonators in the path, and the number of fingers of the first series resonator is 45% less than the minimum number of fingers of all series resonators in the path. As can be seen from the figure, the minimum suppression in the 1900MHz-1910MHz region of frequency band B is approximately -4dB at 1910MHz, with its starting position at 1904MHz.

[0063] One embodiment of this application also provides a communication device, including the multiplexer according to the foregoing.

[0064] The specific structure and principle of the multiplexer can be referred to in the foregoing embodiments. Communication equipment can use the multiplexer in the foregoing embodiments, which also has the corresponding technical effects.

[0065] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A multiplexer, characterized in that, The device includes an antenna terminal, a first filter connected to the antenna terminal, and a second filter connected to the antenna terminal. The frequency of the first passband of the first filter is less than the frequency of the second passband of the second filter. The first filter includes a multi-stage series-parallel resonator. The frequency corresponding to the resonance peak formed by the electromagnetic coupling of the first-stage series-parallel resonator closest to the antenna terminal in the first filter is located near the low-frequency side of the second passband.

2. The multiplexer according to claim 1, characterized in that, The period of at least one of the resonators in the first-stage series-parallel resonators is less than the first standard value; And / or, the number of fingers of at least one of the resonators in the first-stage series-parallel resonators is less than the second standard value.

3. The multiplexer according to claim 2, characterized in that, The deviation between the cycle and the first standard value is 3%-5%; And / or, the deviation between the number of indexes and the second standard value is 40%-55%.

4. The multiplexer according to claim 1, characterized in that, The first-stage series-parallel resonator includes a first series resonator and a first parallel resonator. The first series resonator is connected to the antenna terminal, and the first parallel resonator is connected to either end of the first series resonator. The first-stage series-parallel resonator satisfies at least one of the following: The period of the first series resonator is 3%-5% smaller than the period of the smallest electrode among the other series resonators in the first filter; The number of fingers in the first series resonator is 40%-55% smaller than the minimum number of fingers in the remaining series resonators in the first filter; The period of the first parallel resonator is 3%-5% smaller than the period of the smallest electrode among the other parallel resonators in the first filter; The number of fingers in the first parallel resonator is 40%-55% smaller than the minimum number of fingers in the other parallel resonators in the first filter.

5. The multiplexer according to any one of claims 1-4, characterized in that, The insertion loss of the second filter near the low-frequency side is less than or equal to -3 dB.

6. The multiplexer according to any one of claims 1-4, characterized in that, The frequency interval between the first passband and the second passband is 30MHz-50MHz.

7. The multiplexer according to any one of claims 1-4, characterized in that, The first passband has a frequency of 1805MHz-1880MHz, the second passband has a frequency of 1920MHz-1980MHz, and the resonant peak frequency is located between 1900MHz-1910MHz.

8. The multiplexer according to any one of claims 1-4, characterized in that, The multiplexer also includes a third filter connected to the antenna terminal and a fourth filter connected to the antenna terminal; The third filter is used to implement the transmission channel of the Band 3 frequency band, the first filter is used to implement the reception channel of the Band 3 frequency band, the second filter is used to implement the transmission channel of the Band 1 frequency band, and the fourth filter is used to implement the reception channel of the Band 1 frequency band.

9. The multiplexer according to claim 8, characterized in that, The first filter and the second filter have a first resonator circuit topology, and the third filter and the fourth filter have a second resonator circuit topology. The number of resonators in the first resonator circuit topology is different from the number of resonators in the second resonator circuit topology.

10. A communication device, characterized in that, Includes a multiplexer according to any one of claims 1-9.

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