A directional coupler and radio frequency front end module

Abstract

The application relates to the field of radio frequency communication, and discloses a directional coupler. The directional coupler comprises a through main line, a first coupling branch line and a second coupling branch line. The through main line, the first coupling branch line and the second coupling branch line are arranged on a first substrate; wherein the first coupling branch line and the second coupling branch line are arranged on the two sides of the through main line respectively. The first coupling branch line and the second coupling branch line are connected through a coupling connection structure. The coupling connection structure is arranged on a second substrate. The area of the second substrate is smaller than that of the first substrate. The second substrate is welded on the first substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency communication, in particular to a directional coupler and a radio frequency front-end module. BACKGROUND

[0002] The radio frequency front-end module is a core component of a radio frequency communication device, and its main function is to be responsible for the reception and transmission of wireless signals. Power detection needs to be performed in the radio frequency front-end module, and the design of the coupler directly relates to the accuracy and stability of the power detection.

[0003] With the frequency coverage range of the radio frequency mobile terminal becoming wider, a wideband directional coupler needs to be used. Since the signal wavelength corresponding to the low frequency band is relatively long, compared with the directional coupler covering only the high frequency band, the wideband directional coupler covering the low frequency band needs a longer through main line and coupling branch line, which will occupy a larger substrate area, and meanwhile, the insertion loss at the high frequency band is large. SUMMARY

[0004] Therefore, the embodiments of the present application provide a directional coupler and a radio frequency front-end module, which can reduce the occupation of the substrate and reduce the insertion loss.

[0005] The technical scheme of the embodiments of the present application is implemented as follows:

[0006] The embodiments of the present application provide a directional coupler applied to a radio frequency front-end module, which comprises a through main line, a first coupling branch line and a second coupling branch line; the through main line, the first coupling branch line and the second coupling branch line are all arranged on a first substrate; wherein the first coupling branch line and the second coupling branch line are arranged on two sides of the through main line respectively; the first coupling branch line and the second coupling branch line are connected through a coupling connection structure; the coupling connection structure is arranged on a second substrate; the area of the second substrate is smaller than the area of the first substrate; and the second substrate is welded on the first substrate.

[0007] In some embodiments of the present application, the directional coupler further comprises a flatness adjusting module, an isolation adjusting module and an impedance adjusting module; the flatness adjusting module is connected to the first end of the first coupling branch line or the first end of the second coupling branch line; the isolation adjusting module is connected to the second end of the first coupling branch line or the second end of the second coupling branch line; and the impedance adjusting module is connected to the first end of the first coupling branch line or the first end of the second coupling branch line; wherein the first end of the first coupling branch line and the first end of the second coupling branch line are close to the input end of the through main line; and the second end of the first coupling branch line and the second end of the second coupling branch line are close to the output end of the through main line.

[0008] In some embodiments of the application, in the flatness adjustment module, the isolation adjustment module and the impedance adjustment module, the inductive device is disposed on the second substrate; a magnetic flux direction of the inductive device is perpendicular to a magnetic flux direction of the coupling connection structure; in the flatness adjustment module, the isolation adjustment module and the impedance adjustment module, the capacitive device and the resistive device are surface mount devices.

[0009] In some embodiments of the application, the coupling connection structure comprises: the coupling connection structure comprises: an interconnection line, a first via and a first pin; the inductive device comprises: an inductive line, a second via and a second pin; the interconnection line and the inductive line are disposed in at least one metal layer above a bottom metal layer of the second substrate; the first pin and the second pin are disposed in the bottom metal layer of the second substrate; two ends of the interconnection line are led out by the first pin and are respectively welded on the first coupling branch line and the second coupling branch line; the interconnection line and the first pin are connected through the first via; the inductive line is wound into a coil; two ends of the inductive line are led out by the second pin; the inductive line and the second pin are connected through the second via.

[0010] In some embodiments of the application, a plurality of the interconnection lines are arranged in sequence along an extension direction of the straight-through main line; each of the interconnection lines intersects the straight-through main line out of plane; the inductive line is in a spiral shape, and a rotation axis of the inductive line is perpendicular to a connecting surface of the first substrate and the second substrate.

[0011] In some embodiments of the application, a plurality of the interconnection lines are divided into at least one coupling area; in each of the coupling areas, shapes and positions of the interconnection lines are determined based on a corresponding frequency band.

[0012] In some embodiments of the application, the interconnection line is in a spiral shape, and a rotation axis of the interconnection line is perpendicular to a connecting surface of the first substrate and the second substrate; a rotation axis of the inductive line is parallel to the connecting surface of the first substrate and the second substrate.

[0013] In some embodiments of the present application, the flatness adjustment module comprises a first capacitor, a first end of the first capacitor is connected to a first end of the first coupling branch, or a first end of the second coupling branch, a second end of the first capacitor is grounded, the isolation adjustment module comprises a first resistor, a first end of the first resistor is connected to a second end of the first coupling branch, or a second end of the second coupling branch, a second end of the first resistor is grounded, the impedance adjustment module comprises a second resistor and a first inductor, the second resistor and the first inductor are connected in parallel, and one end after being connected in parallel is connected to a first end of the first coupling branch, or a first end of the second coupling branch.

[0014] In some embodiments of the present application, the isolation adjustment module further comprises a second capacitor, a first end of the second capacitor is connected to a second end of the first coupling branch, or a second end of the second coupling branch, and a second end of the second capacitor is grounded.

[0015] The embodiments of the present application also provide a radio frequency front end module, which comprises the directional coupler in the above-mentioned scheme.

[0016] It can be understood that the coupling connection structure is arranged in the second substrate, the connection between the first coupling branch and the second coupling branch is realized, and a larger coupling degree is realized by shorter straight-through main lines and coupling branches. In this way, the occupation of the first substrate is reduced, on the one hand, the area of the first substrate is reduced, and on the other hand, the straight-through main lines, the first coupling branch and the second coupling branch can only occupy one metal layer on the surface of the first substrate, and other metal layers do not need to be occupied. At the same time, the straight-through main lines and the coupling branches are shorter, and the insertion loss is reduced.

[0017] In addition, the coupling connection structure is integrated in the second substrate, so that the coupling connection structure is in a relatively closed environment; a shielding structure can be designed on the second substrate, so that the coupling connection structure can be prevented from being disturbed by surrounding high-power signals, and the accuracy of the signals is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 Structure diagram of the directional coupler provided by the embodiments of the present application Figure One ;

[0020] Figure 2A Structure diagram of directional coupler provided by the embodiment of the present application two;

[0021] Figure 2B Structure diagram of directional coupler provided by the embodiment of the present application Figure Three ;

[0022] Figure 2C Structure diagram of directional coupler provided by the embodiment of the present application Figure Four ;

[0023] Figure 2D Structure diagram of directional coupler provided by the embodiment of the present application Figure Five ;

[0024] Figure 3 Structure diagram of directional coupler provided by the embodiment of the present application Figure Six ;

[0025] Figure 4 Structure diagram of directional coupler provided by the embodiment of the present application Figure Seven ;

[0026] Figure 5 Circuit diagram of directional coupler provided by the embodiment of the present application Figure One ;

[0027] Figure 6 Circuit diagram of directional coupler provided by the embodiment of the present application two;

[0028] Figure 7 Structure diagram of radio frequency front end module provided by the embodiment of the present application. DETAILED DESCRIPTION

[0029] The exemplary embodiments of this application will be described hereinafter with reference to the accompanying drawings. While the exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in various forms and should not be limited to specific embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0030] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without one or more of these specific details. In other instances, well-known features have not been described in detail in order to avoid obscuring aspects of the present application.

[0031] In the drawings, the size of layers, regions, elements, and the like, as well as the size of the relative sizes of the same, can be exaggerated for clarity. The same reference numbers are used throughout the drawings to represent the same elements.

[0032] It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application. Conversely, a second element, component, region, layer or section discussed below could be termed a first element, component, region, layer or section without departing from the teachings of the present application.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. All numerical ranges herein are inclusive of the endpoints.

[0034] As shown in FIG. 1, a directional coupler includes a through main line and a coupling branch line. The through main line is located between two ports of RFin and RFout, and a radio frequency signal is transmitted from the through main line. The coupling branch line is located beside the through main line, and the coupling branch line is used to follow the signal change on the through main line, to couple part of the radio frequency signal to the CPLout (coupling output end) and output to a detection module for detection. The coupling branch line needs to reduce the influence on the through main line as much as possible, and the coupling branch line cannot be disturbed by the rest of the high-power signal. Figure 1

[0035] Figure 2A Figure 2B Figure 2C Figure 2D FIGS. 1, 2, 3, 4, 5, and 6 show the external structure of the directional coupler provided by the embodiments of the present application, wherein, Figure 2A FIG. 1 is a top view, Figure 2B FIG. 2 is a left view, Figure 2C FIG. 3 is a front view, and Figure 2D FIG. 4 is a three-dimensional view of different angles.

[0036] Reference is made to FIG. 5, which shows the internal structure of the directional coupler provided by the embodiments of the present application, wherein, Figure 2A ​​​​The directional coupler comprises a through main line 301, a first coupling branch line 401 and a second coupling branch line 402. The through main line 301, the first coupling branch line 401 and the second coupling branch line 402 are arranged on the first substrate 10. The first coupling branch line 401 and the second coupling branch line 402 are arranged on two sides of the through main line 301 respectively.

[0037] With reference to the foregoing Figure 2A The second substrate 20 is welded on the first substrate 10. The area of the second substrate 20 is smaller than the area of the first substrate 10.

[0038] In combination Figure 3 The coupling connection structure 501 is arranged in the second substrate 20. The first coupling branch line 401 and the second coupling branch line 402 are connected through the coupling connection structure 501. The first coupling branch line 401, the second coupling branch line 402 and the coupling connection structure 501 can couple the energy of the through main line 301.

[0039] It should be noted that the substrate (LMT) comprises multiple metal layers. The metal layers can be used to form metal lines to construct a circuit structure.

[0040] For example, with reference to the foregoing Figure 2B The first substrate 10 comprises a top metal layer 101 and a bottom metal layer 102. The through main line 301, the first coupling branch line 401 and the second coupling branch line 402 can be formed in the top metal layer 101, and the bottom metal layer 102 can be used as a ground layer (i.e. a ground terminal).

[0041] For another example, with reference to the foregoing Figure 2B The second substrate 20 comprises a top metal layer 201 and a bottom metal layer 202. The interconnection line 502 of the coupling connection structure can be formed in the top metal layer 201, and the first pin of the coupling connection structure can be formed in the bottom metal layer 202.

[0042] It can be understood that the coupling connection structure 501 arranged in the second substrate 20 can realize the connection between the first coupling branch line 401 and the second coupling branch line 402, so that a larger coupling degree is realized by using shorter through main lines and coupling branch lines. In this way, the occupation of the first substrate 10 is reduced. On the one hand, the area of the first substrate 10 is reduced. On the other hand, the through main line 301, the first coupling branch line 401 and the second coupling branch line 402 can only occupy one metal layer on the surface of the first substrate 10, without occupying other metal layers. At the same time, the through main line and the coupling branch line are shorter, so that the insertion loss is reduced.

[0043] In addition, the coupling connection structure 501 is integrated in the second substrate 20, so that the coupling connection structure 501 is in a relatively closed environment; a shielding structure can be designed on the second substrate 20, so that the coupling connection structure 501 can be prevented from being disturbed by surrounding high-power signals, and the accuracy of the signals is ensured.

[0044] In the embodiments of the present application, compared with the first substrate 10, the second substrate 20 has a smaller area, is flexible to use, easy to process, and easy to realize integrated design of multiple function lines. Therefore, the directional coupler can be miniaturized, has the advantages of easy replication, various forms, and high integration.

[0045] In some embodiments of the present application, referring to Figure 2A The directional coupler further includes a flatness adjusting module 601, an isolation adjusting module 602, and an impedance adjusting module 603.

[0046] In the embodiments of the present application, the flatness adjusting module 601 can be connected to the first end of the first coupling branch 401, or the flatness adjusting module 601 can also be connected to the first end of the second coupling branch 402. The isolation adjusting module 602 can be connected to the second end of the first coupling branch 401, or the isolation adjusting module 602 can also be connected to the second end of the second coupling branch 402. The impedance adjusting module 603 can be connected to the first end of the first coupling branch 401, or the impedance adjusting module 603 can also be connected to the first end of the second coupling branch 402.

[0047] The first end of the first coupling branch 401 and the first end of the second coupling branch 402 are close to the input end of the through main line 301; the second end of the first coupling branch 401 and the second end of the second coupling branch 402 are close to the output end of the through main line 301.

[0048] It can be understood that by setting the flatness adjusting module 601 and the impedance adjusting module 603, the reflection coefficient of the CPLout end and the coupling flatness can be conveniently adjusted, so that the coupling energy can be well output to the detection module. At the same time, by setting the isolation adjusting module 602, good isolation can be achieved.

[0049] In some embodiments of the present application, referring to Figure 3 Or Figure 4 Among the flatness adjusting module 601, the isolation adjusting module 602, and the impedance adjusting module 603, the inductive device 701 is arranged in the second substrate 20. The magnetic flux direction B of the inductive device 701 is perpendicular to the magnetic flux direction A of the coupling connection structure 501.

[0050] It can be understood that, by arranging the inductive device 701 on the second substrate 20, the metal layer in the second substrate 20 can be directly used to form the inductive device 701, and the surface-mounted inductive device 701 is not needed, so that the design flexibility is improved, and the miniaturization and low cost requirements of the directional coupler are facilitated.

[0051] Meanwhile, by integrating the inductive device 701 in the second substrate 20, the inductive device 701 is in a relatively closed environment; a shielding structure can be designed on the second substrate 20, so that the inductive device 701 can be prevented from being disturbed by surrounding high-power signals, and the signal accuracy is ensured.

[0052] In addition, a certain safety distance is designed between the coupling connection structure 501 and the inductive device 701 on the second substrate 20, and the magnetic flux direction B of the inductive device 701 is perpendicular to the magnetic flux direction A of the coupling connection structure 501, so that the mutual inductance between the coupling connection structure 501 and the inductive device 701 can be effectively reduced, and the signal transmission accuracy is ensured.

[0053] In the embodiment of the application, referring to Figure 2B , the coupling connection structure includes an interconnection line 502, a first via hole 503, and a first pin 504. The inductive device includes an inductive line 702, a second via hole 703, and a second pin 704.

[0054] In the embodiment of the application, referring to Figure 2B , the interconnection line 502 and the inductive line 702 are arranged in at least one metal layer above the bottom metal layer 202 of the second substrate 20; for example, the interconnection line 502 and the inductive line 702 can be arranged in the top metal layer 201 of the second substrate 20. The number of metal layers used by the interconnection line 502 can be determined according to the coupling energy size and directionality.

[0055] Referring to Figure 2B , the first pin 504 and the second pin 704 are arranged in the bottom metal layer 202 of the second substrate 20.

[0056] The two ends of the interconnection line 502 are led out by the first pin 504. The first pin 504 and the top metal layer 101 of the first substrate 10 can be soldered by a solder ball, so that the two ends of the interconnection line 502 can be respectively soldered on the first coupling branch line 401 and the second coupling branch line 402. The interconnection line 502 and the first pin 504 are connected through the first via hole 503.

[0057] In addition, the inductor wire 702 is wound into a coil. Two ends of the inductor wire 702 are led out by the second pin 704. The second pin 704 and the top metal layer 101 of the first substrate 10 can also be soldered by tin balls. The inductor wire 702 and the second pin 704 are connected by the second via hole 703.

[0058] In the embodiments of the present application, the first via hole 503 and the second via hole 703 can extend in a direction perpendicular to the connecting surface (the connecting surface between the first substrate 10 and the second substrate 20), so that the interconnection wire 502 and the inductor wire 702 can be connected to the pin, respectively. In addition, the first pin 504 and the second pin 704 are soldered to the first substrate 10 by tin balls, so that the coupling connection structure 501 and the inductor device 701 can form an electrical connection with the coupling branch.

[0059] In some embodiments of the present application, as shown in Figure 3 , a plurality of interconnection wires 502 are arranged in sequence along the extension direction of the straight-through main wire 301. Each interconnection wire 502 intersects the straight-through main wire 301 in a different plane, so that the energy of the straight-through main wire 301 can be coupled. The inductor wire 702 is in a spiral shape, and the rotation axis of the inductor wire 702 is perpendicular to the connecting surface of the first substrate 10 and the second substrate 20.

[0060] Referring to Figure 3 , the magnetic flux direction A of the coupling connection structure 501 is parallel to the connecting surface, while the magnetic flux direction B of the inductor device 701 is perpendicular to the connecting surface. Therefore, the magnetic flux direction A of the coupling connection structure 501 is perpendicular to the magnetic flux direction B of the inductor device 701, so that the mutual inductance between the coupling connection structure 501 and the inductor device 701 can be effectively reduced.

[0061] In some other embodiments of the present application, referring to Figure 3 , the plurality of interconnection wires 502 can be divided into at least one coupling area; in each coupling area, the shape and position of the interconnection wire 502 are determined based on a corresponding frequency band. That is, one or more coupling areas can be divided, and each coupling area corresponds to a frequency band. Then, the shape and position of the interconnection wire 502 in each coupling area can be designed based on the frequency band, for example, the cross-sectional area or the spacing of the interconnection wire can be designed. In this way, the signals of one or more frequency bands can be coupled, so that the flexibility is improved, and the application range of the directional coupler is expanded.

[0062] It should be noted that the number of CPLout terminals in the directional coupler needs to be set according to the number of coupled frequency bands (that is, the number of coupling regions into which the interconnection line 502 is divided); for example, if the interconnection line 502 is divided into two coupling regions, and coupling of signals of two frequency bands can be implemented, then the number of CPLout terminals also needs to be set to two, and the two CPLout terminals are respectively used to output coupled signals of the two frequency bands.

[0063] In some embodiments of the present application, as shown in Figure 4 , the interconnection line 502 is in a spiral shape, and the rotation axis of the interconnection line 502 is perpendicular to the connecting surface of the first substrate 10 and the second substrate 20. The rotation axis of the inductive device 702 is parallel to the connecting surface of the first substrate 10 and the second substrate 20.

[0064] Referring to Figure 4 , the magnetic flux direction A of the coupling connection structure 501 is perpendicular to the connecting surface, and the magnetic flux direction B of the inductive device 701 is parallel to the connecting surface, so the magnetic flux direction A of the coupling connection structure 501 and the magnetic flux direction B of the inductive device 701 are perpendicular to each other, thereby effectively reducing the mutual inductance between the coupling connection structure 501 and the inductive device 701.

[0065] In some embodiments of the present application, among the flatness adjustment module 601, the isolation degree adjustment module 602, and the impedance adjustment module 603, the capacitor device and the resistor device are surface mounted devices (SMD).

[0066] It can be understood that the capacitor device and the resistor device are surface mounted devices, which improves flexibility and is easy to process and adjust the frequency band and bandwidth.

[0067] In some embodiments of the present application, as shown in Figure 5 , the flatness adjustment module 601 includes a first capacitor C1. The first end of the first capacitor C1 is connected to the first end of the first coupling branch line 401, or connected to the first end of the second coupling branch line 402. The second end of the first capacitor C1 is grounded.

[0068] Referring back to Figure 5 , the isolation degree adjustment module 602 includes a first resistor R1. The first end of the first resistor R1 is connected to the second end of the first coupling branch line 401, or connected to the second end of the second coupling branch line 402. The second end of the first resistor R1 is grounded.

[0069] Referring back to Figure 5The impedance adjusting module 603 comprises a second resistor R2 and a first inductor L1. The second resistor R2 and the first inductor L1 are connected in parallel; and one end of the parallel connection is connected to the first end of the first coupling branch 401, or the first end of the second coupling branch 402.

[0070] In some embodiments of the present application, as shown in Figure 6 The isolation adjusting module 602 further comprises a second capacitor C2. The first end of the second capacitor C2 is connected to the second end of the first coupling branch 401, or the second end of the second coupling branch 402. The second end of the second capacitor C2 is grounded.

[0071] The present application also provides a radio frequency front end module, as shown in Figure 7 The radio frequency front end module 90 comprises the directional coupler 80. The directional coupler 80 comprises the technical features of the above embodiments.

[0072] It should be noted that, in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or devices including a series of elements not only include those elements, but also include other elements not explicitly listed, or further include inherent elements of such processes, methods, articles, or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device including the element.

[0073] The above-mentioned serial numbers of the embodiments of the present application are only for description, and do not represent the advantages or disadvantages of the embodiments. The methods disclosed in the several method embodiments provided by the present application can be combined arbitrarily without conflict, to obtain new method embodiments. The features disclosed in the several product embodiments provided by the present application can be combined arbitrarily without conflict, to obtain new product embodiments. The features disclosed in the several method or device embodiments provided by the present application can be combined arbitrarily without conflict, to obtain new method or device embodiments.

[0074] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A directional coupler applied to a radio frequency front end module, characterized in that, The directional coupler comprises a through main line, a first coupling branch line and a second coupling branch line; The through main line, the first coupling branch line and the second coupling branch line are arranged on a first substrate; the first coupling branch line and the second coupling branch line are arranged on two sides of the through main line, respectively; The first coupling branch line and the second coupling branch line are connected through a coupling connection structure; the coupling connection structure is arranged on a second substrate; The area of the second substrate is smaller than the area of the first substrate; the second substrate is welded on the first substrate; The directional coupler further comprises a flatness adjusting module, an isolation adjusting module and an impedance adjusting module; In the flatness adjusting module, the isolation adjusting module and the impedance adjusting module, an inductive device is arranged on the second substrate; the magnetic flux direction of the inductive device is perpendicular to the magnetic flux direction of the coupling connection structure; In the flatness adjusting module, the isolation adjusting module and the impedance adjusting module, a capacitive device and a resistive device are surface mount devices.

2. The directional coupler of claim 1, wherein, The flatness adjusting module is connected to the first end of the first coupling branch line or the first end of the second coupling branch line; The isolation adjusting module is connected to the second end of the first coupling branch line or the second end of the second coupling branch line; The impedance adjusting module is connected to the first end of the first coupling branch line or the first end of the second coupling branch line; The first end of the first coupling branch line and the first end of the second coupling branch line are close to the input end of the through main line; the second end of the first coupling branch line and the second end of the second coupling branch line are close to the output end of the through main line.

3. The directional coupler of claim 2, wherein, The coupling connection structure comprises an interconnection line, a first through hole and a first pin; the inductive device comprises an inductive line, a second through hole and a second pin; The interconnection line and the inductive line are arranged in at least one metal layer above the bottom metal layer of the second substrate; The first pin and the second pin are arranged in the bottom metal layer of the second substrate; The two ends of the interconnection line are led out by the first pin and are welded on the first coupling branch line and the second coupling branch line, respectively; the interconnection line and the first pin are connected through the first through hole; The inductive line is wound into a coil; the two ends of the inductive line are led out by the second pin; the inductive line and the second pin are connected through the second through hole.

4. The directional coupler of claim 3, wherein A plurality of the interconnection lines are arranged in sequence along the extension direction of the through main line; each of the interconnection lines intersects the through main line out of plane; The inductive line is in a spiral shape, and the rotation axis of the inductive line is perpendicular to the connecting surface of the first substrate and the second substrate.

5. The directional coupler of claim 4, wherein A plurality of the interconnection lines are divided into at least one coupling area; In each of the coupling areas, the shape and position of the interconnection line are determined based on a corresponding frequency band.

6. The directional coupler of claim 3, wherein: the interconnection line is in a spiral shape, and an axis of rotation of the interconnection line is perpendicular to a connecting surface of the first substrate and the second substrate; an axis of rotation of the inductive line is parallel to the connecting surface of the first substrate and the second substrate.

7. The directional coupler of claim 2, wherein: the flatness adjustment module comprises a first capacitor, a first end of the first capacitor is connected to a first end of the first coupled branch line, or a first end of the second coupled branch line, and a second end of the first capacitor is grounded; the isolation adjustment module comprises a first resistor, a first end of the first resistor is connected to a second end of the first coupled branch line, or a second end of the second coupled branch line, and a second end of the first resistor is grounded; the impedance adjustment module comprises a second resistor and a first inductor, the second resistor and the first inductor are connected in parallel, and one end of the parallel connection is connected to the first end of the first coupled branch line, or the first end of the second coupled branch line.

8. The directional coupler of claim 7, wherein, the isolation adjustment module further comprises a second capacitor; a first end of the second capacitor is connected to the second end of the first coupled branch line, or the second end of the second coupled branch line, and a second end of the second capacitor is grounded.

9. A radio frequency front-end module, characterized in that, the radio frequency front end module comprises the directional coupler of any one of claims 1 to 8.

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