Barlow structure, power amplifier and radio frequency front end module

Abstract

The application discloses a balun structure, a power amplifier and a radio frequency front end module. The balun structure comprises a first balanced end, a second balanced end and an unbalanced end. The balun structure further comprises a first coupling line, a first end of the first coupling line being connected to the first balanced end, and a second end of the first coupling line being used for grounding; a second coupling line, a first end of the second coupling line being connected to the second balanced end, and a second end of the second coupling line being used for grounding; and a third coupling line, a first end of the third coupling line being connected to the unbalanced end, and a second end of the third coupling line being used for grounding. The first coupling line and the second coupling line are respectively coupled to the third coupling line. The first coupling line is arranged on a first metal layer, the second coupling line is arranged on a second metal layer, and the first metal layer and the second metal layer are different metal layers. The two main-stage coupling lines are arranged on different metal layers, and the two main-stage coupling lines are coupled to the third coupling line as a secondary stage, so that the voltage peaks generated by the two main-stage coupling lines due to coupling are relatively close, and the balance of the balun is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency technology, in particular to a balun structure, a power amplifier and a radio frequency front-end module. BACKGROUND

[0002] A balun is a transformer capable of realizing balanced-unbalanced conversion, which generally includes a primary coil, a secondary coil, two balanced ends and an unbalanced end. Generally, the primary coil is connected in series between the two balanced ends with the middle node grounded, and one end of the secondary coil is connected to the unbalanced end and the other end is grounded.

[0003] In the background art, the primary coil of the balun is divided into two segments from the middle node, and the two segments of the primary coil have a voltage imbalance problem. Therefore, how to improve the balance of the balun is a problem to be solved at present. SUMMARY

[0004] The present application provides a balun structure, a power amplifier and a radio frequency front-end module, which can improve the balance of the balun structure.

[0005] The first aspect of the present application provides a balun structure, which includes a first balanced end, a second balanced end and an unbalanced end, and further includes a first coupling line, a second coupling line and a third coupling line; a first end of the first coupling line is connected to the first balanced end, a first end of the second coupling line is connected to the second balanced end, and the first coupling line and the second coupling line are connected in series between the first balanced end and the second balanced end; a first end of the third coupling line is connected to the unbalanced end, and a second end of the third coupling line is used for grounding; wherein the first coupling line is arranged on a first metal layer, the second coupling line is arranged on a second metal layer, the first metal layer and the second metal layer are different metal layers, and the first coupling line and the second coupling line are both coupled with the third coupling line.

[0006] As a feasible implementation manner, the third coupling line includes at least one sub-coupling line coupled with the first coupling line and the second coupling line; or the third coupling line includes two groups of parallel sub-coupling lines, the first coupling line and the second coupling line are respectively coupled with one group of the two groups of parallel sub-coupling lines, and the number of each group of sub-coupling lines is at least one.

[0007] As a feasible implementation, the third coupling line comprises a first sub-coupling line, a second sub-coupling line, a third sub-coupling line and a fourth sub-coupling line; the first sub-coupling line and the third sub-coupling line are arranged on the first metal layer and coupled with the first coupling line at least, and the second sub-coupling line and the fourth sub-coupling line are arranged on the second metal layer and coupled with the second coupling line at least; the first end of the first sub-coupling line and the first end of the second sub-coupling line are connected to the unbalanced end respectively, the first end of the third sub-coupling line is connected to the second end of the first sub-coupling line, and the second end of the third sub-coupling line is grounded; the first end of the fourth sub-coupling line is connected to the second end of the second sub-coupling line, and the second end of the fourth sub-coupling line is grounded.

[0008] As a feasible implementation, the third coupling line comprises a first sub-coupling line, a second sub-coupling line, a third sub-coupling line and a fourth sub-coupling line; the first end of the first sub-coupling line is connected to the unbalanced end, the second end of the first sub-coupling line is connected to the first end of the second sub-coupling line, and the second end of the second sub-coupling line is grounded; the first end of the third sub-coupling line is connected to the unbalanced end, the second end of the third sub-coupling line is connected to the first end of the fourth sub-coupling line, and the second end of the fourth sub-coupling line is grounded; the first end of the fourth sub-coupling line is connected to the first end of the second sub-coupling line, and the second end of the fourth sub-coupling line is connected to the second end of the second sub-coupling line; wherein, the first sub-coupling line and the third sub-coupling line are arranged on the first metal layer and located on both sides of the first coupling line, and the second sub-coupling line and the fourth sub-coupling line are arranged on the second metal layer and located on both sides of the second coupling line.

[0009] As a feasible implementation, the third coupling line comprises a first sub-coupling line and a second sub-coupling line, the first sub-coupling line is arranged on the first metal layer and coupled with the first coupling line, and the second sub-coupling line is arranged on the second metal layer and coupled with the second coupling line; the first end of the first sub-coupling line and the first end of the second sub-coupling line are connected to the unbalanced end respectively, and the second end of the first sub-coupling line and the second end of the second sub-coupling line are grounded respectively.

[0010] As a feasible implementation, the third coupling line includes a first sub-coupling line and a second sub-coupling line, the first sub-coupling line is arranged on the first metal layer, and the second sub-coupling line is arranged on the second metal layer; the first balun structure further includes: a fourth coupling line, a first end of the fourth coupling line is connected to a first end of the first coupling line, and a second end of the fourth coupling line is connected to a second end of the first coupling line; and a fifth coupling line, a first end of the fifth coupling line is connected to a first end of the second coupling line, and a second end of the fifth coupling line is connected to a second end of the second coupling line; wherein the fourth coupling line is located on the first metal layer, and the fourth coupling line and the first coupling line are located on two sides of the first sub-coupling line respectively; and the fifth coupling line is located on the second metal layer, and the fifth coupling line and the second coupling line are located on two sides of the second sub-coupling line respectively.

[0011] The balun structure provided in the first aspect of the present application can improve the balance of the balun by arranging two main-stage coupling lines on different metal layers and coupling the two main-stage coupling lines with the third coupling line as a secondary stage, so that the voltage peaks generated by the coupling of the two main-stage coupling lines are close to each other.

[0012] The balun structure provided in the second aspect of the present application can be integrated in a chip, and each of the first coupling line, the second coupling line, the fourth coupling line and the fifth coupling line as a main stage is coupled with the two sub-coupling lines of the third coupling line as a secondary stage, and the coupling voltages generated on the main-stage coupling lines are almost the same, thereby improving the balance of the balun.

[0013] The balun structure provided in the second aspect of the present application can be integrated in a chip, and each of the first coupling line, the second coupling line, the fourth coupling line and the fifth coupling line as a main stage is coupled with the two sub-coupling lines of the third coupling line as a secondary stage, and the coupling voltages generated on the main-stage coupling lines are almost the same, thereby improving the balance of the balun.

[0014] The third aspect of the present application provides a balun structure, the balun structure comprising M first primary coupling lines and M first secondary coupling lines, the M first primary coupling lines and the M first secondary coupling lines one-to-one corresponding are arranged on M metal layers, and the primary coupling line and the secondary coupling line on the same metal layer are coupled; the projection of any two first primary coupling lines located on different metal layers on any metal layer has at least partial overlap; the projection of any two first secondary coupling lines located on different metal layers on any metal layer has at least partial overlap; wherein M is a positive integer and M is greater than or equal to 2.

[0015] The balun structure provided in the second aspect of the present application enables a plurality of primary coupling lines to be coupled with the same secondary coupling line, compared with the traditional balun in which each primary coupling line is coupled with different parts of the secondary coupling line, the voltage peak value generated by coupling on different primary coupling lines is closer, thereby improving the balance of the balun, and the coupling degree of the balun structure can also be improved.

[0016] The fourth aspect of the present application provides a power amplifier, the power amplifier comprising a first power amplification circuit, a second power amplification circuit and the balun structure of the first aspect or the second aspect, wherein the first balance end of the balun structure is connected to the output end or the input end of the first power amplification circuit, and the second balance end of the balun structure is connected to the output end or the input end of the second power amplification circuit.

[0017] The fifth aspect of the present application provides a radio frequency front-end module, the radio frequency front-end module comprising a substrate and a first chip arranged on the substrate, the first chip being integrated with the balun structure of the first aspect or the second aspect, or the power amplifier of the third aspect.

[0018] Based on the balun structure provided in the present application having good balance, the balance of the power amplifier and the radio frequency front-end module adopting the above balun structure can also be improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0020] Figure 1 A schematic diagram of a balun structure in the related art is shown.

[0021] Figure 2A circuit diagram of a power amplifier provided by an embodiment of the present application is shown;

[0022] Figure 3 A circuit diagram of a power amplifier provided by another embodiment of the present application is shown;

[0023] Figure 4 A circuit diagram of a power amplifier provided by yet another embodiment of the present application is shown;

[0024] Figure 5 A schematic diagram of a balun structure provided by an embodiment of the present application is shown;

[0025] Figure 6a A schematic diagram of a balun structure provided by another embodiment of the present application is shown;

[0026] Figure 6b A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0027] Figure 7a A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0028] Figure 7b A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0029] Figure 8 A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0030] Figure 9 A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0031] Figure 10 A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0032] Figure 11 A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0033] Figure 12a A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0034] Figure 12b A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown;

[0035] Figure 13 A schematic diagram of a balun structure provided by yet another embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application, so that those skilled in the art can better understand the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0037] The terms "first", "second", and the like in the present application are used to distinguish different objects, and are not used to describe a specific sequence. The term "multiple" refers to two or more. The term "and / or" refers to at least one of the listed objects, for example, "A and / or B" can be any of the following 3 cases: including A but not including B, including B but not including A, and including A and B.

[0038] In the present application, unless otherwise explicitly specified or limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly. For example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication between two elements, or it can be only surface contact. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units not listed, or optionally also includes other steps or units inherent to the process, method, product or device.

[0040] In this document, the term "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive or alternative to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0041] In the related art, as Figure 1As shown, the balun generally includes a primary winding M1, a secondary winding Sec, two balanced ends Bal 1, Bal 2 and an unbalanced end Unb. Generally, the primary winding M1 is connected in series between the two balanced ends Bal 1 and Bal 2, one end of the secondary winding Sec is connected to the unbalanced end Unb, and the other end is grounded. Assuming that the voltage peak value of the unbalanced end Unb is V, and the voltage peak value of the grounded end is close to 0, the secondary winding Sec presents a rule that the voltage peak value gradually decays from the unbalanced end to the grounded end from V to 0.

[0042] Since the primary winding M1 is coupled with the secondary winding Sec, the voltage amplitude of each node of the primary winding M1 has a multiple relationship with the voltage amplitude of the corresponding node of the secondary winding Sec, and therefore the primary winding M1 also presents a rule that the voltage peak value gradually decays from one balanced end to the other balanced end from k*V to 0 (k is the transformation ratio of the balun). If the primary winding M1 of the balun is divided into two segments from the middle node C1, such as M11 and M12 in Figure 1 , the voltage peak value on M11 presents a rule that gradually decays from the balanced end Bal 1 to the middle node C1 from k*V to 1 / 2k*V, and the voltage peak value on M12 presents a rule that gradually rises from the balanced end Bal 2 to the middle node C1 from 0 to 1 / 2k*V.

[0043] It can be seen that the voltage peak value variation rules of the two balanced ends to the middle node C1 of the primary winding in the related art are completely opposite, and the voltages on the two segments of the primary winding M11 and M12 are quite different, which leads to poor balance of the balun.

[0044] Based on this, the first aspect of the present application provides a balun structure capable of improving the balance of the balun. The balun structure can be applied to a power amplifier, specifically, at least one of the input impedance matching network, the inter-stage impedance matching network and the output impedance matching network of the power amplifier.

[0045] As an implementation manner, as shown in Figure 2 , when the input stage of the power amplifier 202 is a differential power amplification circuit, and the front-stage circuit 201 of the power amplifier is a single-ended output, the balun structure of the present application can be used in the input impedance matching network of the power amplifier, so as to convert the input impedance while converting one unbalanced signal from the front-stage circuit into a pair of balanced signals, so that the differential power amplification circuit can perform power amplification thereon.

[0046] As an implementation manner, as shown in Figure 3As shown, when the output stage of power amplifier 202 is a differential power amplifier circuit and the subsequent stage circuit of power amplifier is a single-ended input, the balun structure of this application can be used in the output impedance matching network of power amplifier to convert a pair of balanced signals output by differential power amplifier circuit into an unbalanced signal while converting the output impedance, so that the subsequent stage circuit can receive it.

[0047] As one implementation method, such as Figure 4 As shown, when the power amplifier 202 includes at least two stages of power amplifier circuits, one of which is a single-ended power amplifier circuit and the other is a differential power amplifier circuit, taking the differential power amplifier circuit as the stage following the single-ended power amplifier circuit as an example, the balun structure of this application can be used in the interstage impedance matching network between the single-ended power amplifier circuit and the differential power amplifier circuit. This allows for impedance matching between the two stages while converting the unbalanced signal output from the previous stage into a pair of balanced signals, so that the differential power amplifier circuit in the next stage can amplify the power. For example, the differential power amplifier circuit includes a first power amplifier circuit PA1 and a second power amplifier circuit PA2, and the single-ended power amplifier circuit includes a third power amplifier circuit PA3. The output terminal of the third power amplifier circuit PA3 is connected to the unbalanced terminal Unb of the interstage balun, the first balanced terminal Bal1 of the interstage balun is connected to the input terminal of the first power amplifier circuit PA1, and the second balanced terminal Bal2 of the balun structure is connected to the input terminal of the second power amplifier circuit PA2. Optionally, when the differential power amplifier circuit is the output stage of a power amplifier, an output balun can also be provided at the output terminal of the differential power amplifier circuit. Either or both of the inter-stage balun and the output balun can adopt the balun structure of this application.

[0048] Please refer to Figure 5 , Figure 5 A balun structure according to an embodiment of this application is shown. For example... Figure 5 As shown, the balun structure includes a first balanced end, a second balanced end, and an unbalanced end, as well as a first coupling line 11, a second coupling line 12, and a third coupling line 13. The first coupling line 11 and the second coupling line 12 are primary coupling lines, connected in series between the first and second balanced ends. The third coupling line 13 is a secondary coupling line, with one end connected to the unbalanced end and the other end grounded. For example, the first end S1 of the third coupling line 13 is connected to the unbalanced end, and the second end S2 is grounded; or, the first end S1 of the third coupling line 13 is grounded, and the second end S2 is connected to the unbalanced end.

[0049] Optionally, the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected to realize the series connection of the first coupling line 11 and the second coupling line 12; or the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected to two equipotential points respectively to realize the series connection.

[0050] As an implementation, the second end of the first coupling line 11 and the second end of the second coupling line 12 are grounded to realize the series connection of the first coupling line 11 and the second coupling line 12 and further improve the balance of the balun structure. For example, the first end of the first coupling line 11 is connected to the first balanced end, the second end of the first coupling line 11 is grounded, the first end of the second coupling line 12 is connected to the second balanced end, and the second end of the second coupling line 12 is grounded. Optionally, the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected to the same ground terminal; or the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected to different ground terminals respectively.

[0051] As an implementation, the second end of the first coupling line 11 and the second end of the second coupling line 12 are grounded through capacitors, which can improve the balance of the balun structure and utilize the ground capacitors to participate in impedance matching. Optionally, the second end of the first coupling line 11 and the second end of the second coupling line 12 can be grounded through different capacitors respectively, and only the capacitance values of the two capacitors need to be consistent; or the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected to the same capacitor, which can reduce the circuit components and is conducive to the miniaturization design of the power amplifier and the radio frequency front-end module.

[0052] In the embodiment, the first coupling line 11 and the second coupling line 12 are coupled to the third coupling line 13. For example, the part of the third coupling line 13 coupled to the first coupling line 11 is referred to as the first part, and the part of the third coupling line 13 coupled to the second coupling line 12 is referred to as the second part. Optionally, the first part and the second part include the same part of the third coupling line 13, or the first part and the second part include two parts of the third coupling line 13 in parallel connection, so that the voltage peaks generated in the first coupling line 11 and the second coupling line 12 are relatively close, which can improve the balance of the balun structure.

[0053] Further, the first part and the second part can be the same part of the third coupling line 13; or the first part and the second part are in parallel connection, so that the voltage peaks generated in the first coupling line 11 and the second coupling line 12 are almost consistent, which can further improve the balance of the balun structure.

[0054] In this embodiment, the first coupling line 11 and the second coupling line 12 are located in different metal layers. For example, the first coupling line 11 is disposed in the first metal layer L1, and the second coupling line is disposed in the second metal layer L2. To achieve good coupling with both the first coupling line 11 and the second coupling line 12, as one implementation method, such as... Figure 5 As shown in (a), the third coupling line 13 can be disposed in either the first metal layer L1 or the second metal layer L2, and its projection on the other layer is close to or partially overlaps with the first coupling line or the second coupling line of that layer; for example, the third coupling line 13 is disposed in the first metal layer L1 and close to the first coupling line 11, and the projection of the third coupling line 13 on the second metal layer L2 is close to or at least partially overlaps with the second coupling line 12, so that the third coupling line 13 can be coupled with both the first coupling line 11 and the second coupling line 12. Alternatively, the third coupling line 13 is disposed in the second metal layer L2 and close to the second coupling line 12, and the projection of the third coupling line 13 on the first metal layer L1 is close to or at least partially overlaps with the first coupling line 11, so that the third coupling line 13 can be coupled with both the first coupling line 11 and the second coupling line 12. For example, the first metal layer L1 is substantially parallel to the second metal layer L2, and the projections of the first coupling line 11 and the second coupling line 12 on the first metal layer L1 or the second metal layer L2 overlap with each other. The third coupling line can be disposed on any metal layer and is adjacent to the first coupling line 11 or the second coupling line 12 on that metal layer. In this embodiment, both the first coupling line 11 and the second coupling line 12 are coupled to the entire third coupling line 13, and the voltage peaks generated by the coupling are substantially the same, thereby improving the balance of the balun.

[0055] As another implementation method, such as Figure 5As shown in (b) of FIG. 1, the third coupling line 13 is partially disposed in the first metal layer L1 and partially disposed in the second metal layer L2, and the portion of the third coupling line 13 disposed in the first metal layer L1 is in parallel with the portion of the third coupling line 13 disposed in the second metal layer L2; or, the portion of the third coupling line 13 disposed in the first metal layer L1 is coupled with both the first coupling line 11 and the second coupling line 12, and the portion of the third coupling line 13 disposed in the second metal layer L2 is also coupled with both the first coupling line 11 and the second coupling line 12. In this way, the portion of the third coupling line 13 coupled with the first coupling line 11 and the portion of the third coupling line 13 coupled with the second coupling line 12 are consistent or in parallel, and the voltage peaks generated by the first coupling line 11 and the second coupling line 12 due to the coupling are substantially consistent, thereby improving the balance of the balun. Exemplarily, the first coupling line 11 and the second coupling line 12 can be both coupled with the complete third coupling line. In order to generate good coupling with the first coupling line 11 and the second coupling line 12, the portion of the third coupling line 13 disposed in the first metal layer L1 is adjacent to the first coupling line 11, and the projection of the portion of the third coupling line 13 in the second metal layer L2 is adjacent to or at least partially overlaps with the second coupling line 12; the portion of the third coupling line 13 disposed in the second metal layer L2 is adjacent to the second coupling line 12, and the projection of the portion of the third coupling line 13 in the first metal layer L1 is adjacent to or at least partially overlaps with the first coupling line 11. Exemplarily, the projection of the portion of the third coupling line 13 in the first metal layer L1 in the second metal layer L2 substantially overlaps with the second coupling line 12, and the projection of the portion of the third coupling line 13 in the second metal layer L2 in the first metal layer L1 substantially overlaps with the first coupling line 11, so that the degrees of coupling of the first coupling line 11 and the second coupling line 12 with the third coupling line 13 are more close, thereby further improving the balance of the balun. Exemplarily, the portion of the third coupling line 13 in the first metal layer L1 and the portion of the third coupling line 13 in the second metal layer L2 substantially overlap in the projection in any metal layer, so as to facilitate the connection of the two portions; the first coupling line 11 and the second coupling line 12 substantially overlap in the projection in any metal layer, so that the second end of the first coupling line 11 and the second end of the second coupling line 12 can be grounded through the same conductive via hole penetrating the first metal layer and the second metal layer.

[0056] As another embodiment, as Figure 5As shown in (c) of FIG. 1, the third coupling line 13 is located in a different metal layer from the first coupling line 11 and the second coupling line 12, for example, the third coupling line is located in a third metal layer, and the third metal layer is located between the first metal layer L1 and the second metal layer L2. In order to generate good coupling with the first coupling line 11 and the second coupling line 12, the projection of the third coupling line 13 on the first metal layer L1 at least partially overlaps the first coupling line 11, and the projection of the third coupling line 13 on the second metal layer L2 at least partially overlaps the second coupling line 12. Exemplarily, the first metal layer L1, the second metal layer L2 and the third metal layer are substantially parallel, and the projections of the first coupling line 11, the second coupling line 12 and the third coupling line 13 on any metal layer are substantially overlapped, so that the coupling coefficient of the balun can be maximized. In the embodiment, the first coupling line 11 and the second coupling line 12 are coupled with the entire third coupling line 13, and the voltage peaks generated by the coupling of the two are substantially consistent, so that the balance of the balun can be improved.

[0057] Optionally, the first coupling line 11, the second coupling line 12 and the third coupling line 13 can be straight lines, or can be bent, or can be arranged around an axis or in a specific shape, which is not limited in the application.

[0058] The balun structure provided by the embodiment of the application can improve the balance of the balun by arranging two main coupling lines in different metal layers and coupling the two main coupling lines with a third coupling line as a secondary coupling line, so that the voltage peaks generated by the coupling of the two main coupling lines are close to each other, thereby improving the balance of the balun.

[0059] In some embodiments, the third coupling line 13 includes at least one sub-coupling line coupled with the first coupling line 11 and the second coupling line 12, so that the first coupling line 11 and the second coupling line 12 are coupled with at least one same sub-coupling line of the third coupling line 13. Compared with the traditional balun in which the first coupling line 11 and the second coupling line 12 are coupled with different parts of the third coupling line 13 respectively, the voltage peaks generated by the coupling of the first coupling line 11 and the second coupling line 12 are closer to each other, thereby improving the balance of the balun.

[0060] As an implementation, the third coupling line 13 includes a plurality of sub-coupling lines, and the plurality of sub-coupling lines are distributed in the first metal layer and the second metal layer, for example, at least one sub-coupling line is located in the first metal layer, and at least one other sub-coupling line is located in the second metal layer, so that the coupling degree of at least one sub-coupling line with the first coupling line 11 is slightly higher than the coupling degree with the second coupling line 12, and the coupling degree of at least one other sub-coupling line with the first coupling line 11 is slightly lower than the coupling degree with the second coupling line 12, so that the coupling degree of the third coupling line 13 as a whole with the first coupling line 11 and the second coupling line 12 is close, and the balance of the balun can be further improved.

[0061] As an implementation, the third coupling line 13 includes a plurality of sub-coupling lines, and the plurality of sub-coupling lines are distributed in the first metal layer and the second metal layer, for example, at least one sub-coupling line is located in the first metal layer, and at least one other sub-coupling line is located in the second metal layer, so that the coupling degree of at least one sub-coupling line with the first coupling line 11 is slightly higher than the coupling degree with the second coupling line 12, and the coupling degree of at least one other sub-coupling line with the first coupling line 11 is slightly lower than the coupling degree with the second coupling line 12, so that the coupling degree of the third coupling line 13 as a whole with the first coupling line 11 and the second coupling line 12 is close, and the balance of the balun can be further improved.

[0062] In some embodiments, the third coupling line 13 includes two groups of parallel sub-coupling lines, the first coupling line 11 and the second coupling line 12 are coupled with one group of the two groups of parallel sub-coupling lines respectively, so that the voltage peak value distribution rules of the two groups of parallel sub-coupling lines are substantially the same, and the voltage peak value distribution rules generated by coupling on the first coupling line 11 and the second coupling line 12 are also substantially the same, thereby effectively improving the balance of the balun. Each group of sub-coupling lines includes at least one sub-coupling line, and optionally, when a group includes a plurality of coupling lines, the plurality of sub-coupling lines in the same group can be connected in parallel or in series. The plurality of sub-coupling lines in the same group can be located in the same metal layer or different metal layers.

[0063] In one embodiment, as Figure 6a and Figure 6bAs shown, the first coupling line 11 of the balun structure is arranged on the first metal layer L1, the second coupling line 12 is arranged on the second metal layer L2, the third coupling line 13 includes a first sub-coupling line 131, a second sub-coupling line 132, a third sub-coupling line 133 and a fourth sub-coupling line 134, the first sub-coupling line 131 and the third sub-coupling line 133 are both arranged on the first metal layer L1 and are respectively coupled with the first coupling line 11, and the second sub-coupling line 132 and the fourth sub-coupling line 134 are both arranged on the second metal layer L2 and are respectively coupled with the second coupling line 12. Among them, the first sub-coupling line 131 and the third sub-coupling line 133 located on the first metal layer L1 are a group and are connected in series with each other, the second sub-coupling line 132 and the fourth sub-coupling line 134 located on the second metal layer L2 are a group and are connected in series with each other, and the two groups of sub-coupling lines after being connected in series are connected in parallel with each other. Specifically, the first end P11 of the first coupling line 11 is connected to the first balanced end Bal 1, the second end P12 of the first coupling line 11 is grounded, the first end P21 of the second coupling line 12 is connected to the second balanced end Bal 2, and the second end P22 of the second coupling line 12 is grounded. The first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 are respectively connected to the unbalanced end Unb, the first end of the third sub-coupling line 133 is connected to the second end of the first sub-coupling line 131, and the second end of the third sub-coupling line 133 is grounded; the first end of the fourth sub-coupling line 134 is connected to the second end of the second sub-coupling line 132, and the second end of the fourth sub-coupling line 132 is grounded.

[0064] Optionally, the balun structure in the embodiment can be arranged on a substrate of a radio frequency front end module or integrated in a chip. Correspondingly, the first metal layer L1 and the second metal layer L2 are different metal layers in the substrate or the chip, and the two adjacent metal layers can be separated by an insulating medium layer. When the balun structure is integrated in the chip, the chip can be an HBT (heterojunction bipolar transistor) chip or an IPD (Integrated Passive Device) chip, and can also be a chip based on III-V compound semiconductors or a silicon chip. The type of the chip is not limited in the present application.

[0065] In the embodiment, the two groups of sub-coupling lines on the first metal layer L1 and the second metal layer L2 are in parallel relationship, and the variation law of the voltage peak value is consistent. Therefore, when the first coupling line 11 and the second coupling line 12 are coupled with one group of sub-coupling lines respectively, the voltage peak values generated by the coupling of the first coupling line 11 and the second coupling line 12 are also almost consistent, thereby effectively improving the balance of the balun. On the other hand, when the balun structure is integrated in a chip, the thickness of each layer in the chip is very thin, and the distance between the first metal layer and the second metal layer is very close. Therefore, while the first coupling line 11 is coupled with the first sub-coupling line 131 and the third sub-coupling line 133 located in the first metal layer, the first coupling line 11 is also coupled between the second sub-coupling line 132 and the fourth sub-coupling line 134 located in the other metal layer. Similarly, while the second coupling line 12 is coupled with the second sub-coupling line 132 and the fourth sub-coupling line 134 located in the second metal layer, the second coupling line 12 is also coupled between the first sub-coupling line 131 and the third sub-coupling line 133 located in the other metal layer. Therefore, the first coupling line 11 and the second coupling line 12 are substantially coupled with the four sub-coupling lines of the third coupling line 133, and the coupling voltages generated by the first coupling line 11 and the second coupling line 12 are almost consistent, thereby effectively improving the balance of the balun.

[0066] The first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 are both the first end S1 of the third coupling line 13. Alternatively, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 can be connected through the conductive via 1 penetrating the first metal layer L1 and the second metal layer L2, and then connected to the unbalanced end Unb through the same connecting line. Alternatively, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 can be connected to the unbalanced end Unb through different conductive vias and lines respectively, which are not limited in the present application.

[0067] The second end of the third sub-coupling line 133 and the second end of the fourth sub-coupling line 134 are both the second end S2 of the third coupling line 13. Alternatively, the second end of the third sub-coupling line 133 and the second end of the fourth sub-coupling line 134 can be connected through the conductive via 2 penetrating the first metal layer L1 and the second metal layer L2, and then grounded through the same connecting line. Alternatively, the second end of the third sub-coupling line 133 and the second end of the fourth sub-coupling line 134 can be grounded through different conductive vias and lines respectively, which are not limited in the present application.

[0068] As an implementation manner, the plurality of sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape arranged along the same axis. Further, the plurality of sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 can be substantially parallel.

[0069] As an implementation, in order to make the first sub-coupling line 131 and the third sub-coupling line 133 have good coupling degrees with the first coupling line 11 respectively, the first coupling line 11 is arranged between the first sub-coupling line 131 and the third sub-coupling line 133, that is, the first sub-coupling line 131 and the third sub-coupling line 133 are respectively located on two sides of the first coupling line 11; in order to make the second sub-coupling line 132 and the fourth sub-coupling line 134 have good coupling degrees with the second coupling line 12 respectively, the second coupling line 12 is arranged between the second sub-coupling line 132 and the fourth sub-coupling line 134, that is, the second sub-coupling line 132 and the fourth sub-coupling line 134 are respectively located on two sides of the second coupling line 12.

[0070] Exemplarily, when the first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are all straight line segments, the first sub-coupling line 131 and the third sub-coupling line 133 can be distributed on two sides in the width direction of the first coupling line 11; the second sub-coupling line 132 and the fourth sub-coupling line 134 can be distributed on two sides in the width direction of the second coupling line 12. By arranging the sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 as straight lines, the insertion loss of the balun can be effectively reduced.

[0071] Exemplarily, when the first coupling line, the second coupling line, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are all arranged around the first axis perpendicular to the first metal layer or the second metal layer, the first sub-coupling line 131 and the third sub-coupling line 133 can be distributed on the inner and outer sides of the first coupling line 11 and connected through the connecting lines across the first coupling line 11; the second sub-coupling line 132 and the fourth sub-coupling line 134 can be distributed on the inner and outer sides of the second coupling line 12 and connected through the connecting lines across the second coupling line 12.

[0072] Exemplarily, the shapes of the first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are substantially the same, and the lengths of the traces are close to each other, at this time, the ratio of the inductance of the primary stage to the inductance of the secondary stage is substantially 1:1, which can be applied to the inter-stage impedance matching of the multi-stage power amplifier or used for the output impedance matching of the power amplifier.

[0073] Further, the distance between the first coupling line 11 and the first sub-coupling line 131 and the third sub-coupling line 133 is substantially the same, and the distance between the second coupling line 12 and the second sub-coupling line 132 and the fourth sub-coupling line 134 is substantially the same, so that the spacing between each primary stage coupling line and the two sub-coupling lines on the same layer is equal, and the coupling coefficients are close, which can improve the coupling degree of the balun.

[0074] As an implementation, the projection of the first coupling line 11 on the second metal layer L2 at least partially overlaps with the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 at least partially overlaps with the second sub-coupling line 132; the projection of the third sub-coupling line 133 on the second metal layer L2 at least partially overlaps with the fourth sub-coupling line 134. In this way, the distance between the first sub-coupling line 131 and the first coupling line 11, the distance between the second sub-coupling line 132 and the second coupling line 12, the distance between the third sub-coupling line 133 and the first coupling line 11, and the distance between the fourth sub-coupling line 134 and the second coupling line 12 are similar or equal, which can further improve the coupling degree of the balun.

[0075] Exemplarily, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps with the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps with the second sub-coupling line 132; the projection of the third sub-coupling line 133 on the second metal layer L2 substantially overlaps with the fourth sub-coupling line 134. At this time, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 are connected through the conductive via 1 penetrating the first metal layer L1 and the second metal layer L2, and then connected to the unbalanced end Unb through the same connection line; the second end of the third sub-coupling line 133 and the second end of the fourth sub-coupling line 134 are connected through the conductive via 2 penetrating the first metal layer L1 and the second metal layer L2, and then grounded through the same connection line; the second end of the first coupling line 11 and the second end of the second coupling line 12 are connected through the conductive via 3 penetrating the first metal layer L1 and the second metal layer L2, and then grounded through the same connection line. Thus, while improving the coupling degree of the balun, the wiring can also be facilitated.

[0076] As an implementation, as shown in Figure 6a The first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are all continuous coils or line segments. In order to avoid short-circuiting of the above-mentioned connection lines with the first coupling line or the second coupling line, the connection lines need to be arranged on other metal layers except the first metal layer L1 and the second metal layer L2. At this time, the above-mentioned conductive vias not only penetrate the first metal layer L1 and the second metal layer, but also penetrate the metal layer where the corresponding connection line is located, so that the connection line can be connected with the corresponding coupling line or sub-coupling line.

[0077] As another implementation, at least one of the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 can be segmented and connected to another metal layer through a conductive via to avoid shorting with the first coupling line 11 and the second coupling line 12, so that the connection line can be set without additional metal layers, thereby reducing the number of metal layers occupied by the balun structure and thus reducing the cost.

[0078] For example, as shown in FIG. 1, the first coupling line 11 and the second coupling line 12 are located in the first metal layer L1 and the second metal layer L2 respectively, and the first coupling line 11 and the second coupling line 12 are connected in series through a conductive via via3. Figure 6b For example, as shown in FIG. 1, the first coupling line 11 and the second coupling line 12 are located in the first metal layer L1 and the second metal layer L2 respectively, and the first coupling line 11 and the second coupling line 12 are connected in series through a conductive via via3.

[0079] For example, as shown in FIG. 1, the first coupling line 11 and the second coupling line 12 are located in the first metal layer L1 and the second metal layer L2 respectively, and the first coupling line 11 and the second coupling line 12 are connected in series through a conductive via via3.

[0080] It can be seen that by segmenting some sub-coupled lines in the third coupling line and setting the above-mentioned conductive vias 3 to vias 7, each connecting line can avoid the first coupling line 11 and the second coupling line 12 without occupying additional metal layers, thereby reducing the total number of metal layers occupied by the balun structure and reducing costs.

[0081] In this embodiment, the first coupling line 11 and the second coupling line 12, serving as the primary stage, are respectively disposed on the first metal layer and the second metal layer. The four sub-coupling lines, serving as the secondary stage, are divided into two groups and disposed on the first metal layer and the second metal layer. By connecting the two groups of sub-coupling lines in parallel, the voltage peaks generated by the coupling of the first coupling line 11 and the second coupling line 12 tend to be consistent, thereby effectively improving the balance of the balun. Furthermore, the first sub-coupling line 131 and the second sub-coupling line 132 are connected in parallel on different metal layers, and the third sub-coupling line 133 and the fourth sub-coupling line 134 are connected in parallel on different metal layers. This is equivalent to increasing the metal thickness of the first / second and third / fourth sub-coupling lines, which can improve the quality factor of the coupling lines and thus reduce the insertion loss of the balun.

[0082] In one embodiment, such as Figure 7a and Figure 7b As shown, the first coupling line 11 of the balun structure is disposed on the first metal layer L1, the second coupling line 12 is disposed on the second metal layer L2, and the third coupling line 13 includes a first sub-coupling line 131, a second sub-coupling line 132, a third sub-coupling line 133, and a fourth sub-coupling line 134. The first sub-coupling line 131 and the third sub-coupling line 133 are disposed on the first metal layer L1 and located on both sides of the first coupling line 11, while the second sub-coupling line 132 and the fourth sub-coupling line 134 are disposed on the second metal layer L2 and located on both sides of the second coupling line 12. In this embodiment, the first sub-coupling line 131 and the second sub-coupling line 132 are a group and connected in series, and the third sub-coupling line 133 and the fourth sub-coupling line 134 are a group and connected in series. The two groups of sub-coupling lines connected in series are then connected in parallel. Specifically, the first end P11 of the first coupling line 11 is connected to the first balanced end Bal 1, the second end P12 of the first coupling line 11 is grounded, the first end P21 of the second coupling line 12 is connected to the second balanced end Bal 2, and the second end P22 of the second coupling line 12 is grounded. The first end of the first sub-coupling line 131 is connected to the unbalanced end Unb, the second end of the first sub-coupling line 131 is connected to the first end of the second sub-coupling line 132, and the second end of the second sub-coupling line 132 is grounded; the first end of the third sub-coupling line 133 is also connected to the unbalanced end Unb, the second end of the third sub-coupling line 133 is connected to the first end of the fourth coupling line 134, and the second end of the fourth coupling line 134 is grounded.

[0083] The first end of the first sub-coupling line 131 and the first end of the third sub-coupling line 133 are both the first end S1 of the third coupling line 13. Alternatively, the first end of the first sub-coupling line 131 and the first end of the third sub-coupling line 133 can be connected by a connecting line crossing the first coupling line 11 and connected to the unbalanced end Unb. Alternatively, the first end of the first sub-coupling line 131 and the first end of the third sub-coupling line 133 can be connected to the unbalanced end Unb by different connecting lines respectively, which is not limited in the present application.

[0084] The second end of the second sub-coupling line 132 and the second end of the fourth sub-coupling line 134 are both the second end S2 of the third coupling line 13. Alternatively, the second end of the second sub-coupling line 132 and the second end of the fourth sub-coupling line 134 can be connected by a connecting line crossing the second coupling line 12 and grounded. Alternatively, the second end of the second sub-coupling line 132 and the second end of the fourth sub-coupling line 134 can be grounded by different connecting lines respectively, which is not limited in the present application.

[0085] Alternatively, the second end of the first sub-coupling line 131 and the second end of the third sub-coupling line 133 can be connected to each other or not. Similarly, the first end of the second sub-coupling line 132 and the first end of the fourth sub-coupling line 134 can be connected to each other or not.

[0086] As an embodiment, the plurality of sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape around the same axis. Further, the plurality of sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 can be substantially parallel.

[0087] As an embodiment, in order to make the first sub-coupling line 131 and the third sub-coupling line 133 have good coupling degree with the first coupling line 11 respectively, the first coupling line 11 is arranged between the first sub-coupling line 131 and the third sub-coupling line 133, i.e. the first sub-coupling line 131 and the third sub-coupling line 133 are located on both sides of the first coupling line 11 respectively; in order to make the second sub-coupling line 132 and the fourth sub-coupling line 134 have good coupling degree with the second coupling line 12 respectively, the second coupling line 12 is arranged between the second sub-coupling line 132 and the fourth sub-coupling line 134, i.e. the second sub-coupling line 132 and the fourth sub-coupling line 134 are located on both sides of the second coupling line 12 respectively.

[0088] Exemplarily, when the first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are all straight line segments, the first sub-coupling line 131 and the third sub-coupling line 133 can be distributed on both sides of the width direction of the first coupling line 11 and substantially keep parallel with the first coupling line 11; the second sub-coupling line 132 and the fourth sub-coupling line 134 can be distributed on both sides of the width direction of the second coupling line 12 and substantially keep parallel with the second coupling line 12. By setting the sub-coupling lines of the first coupling line 11, the second coupling line 12 and the third coupling line 13 as straight lines, the insertion loss of the balun can be effectively reduced.

[0089] Exemplarily, when the first coupling line, the second coupling line, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are all arranged around the first axis perpendicular to the first metal layer or the second metal layer, the first sub-coupling line 131 and the third sub-coupling line 133 can be distributed on both sides of the first coupling line 11 and connected by the connecting lines across the first coupling line 11; the second sub-coupling line 132 and the fourth sub-coupling line 134 can be distributed on both sides of the second coupling line 12 and connected by the connecting lines across the second coupling line 12.

[0090] Exemplarily, the shapes of the first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 are substantially the same, and the lengths of the traces are close to each other, so that the ratio of the inductance of the primary stage to the inductance of the secondary stage is substantially 1:1, which can be applied to the inter-stage impedance matching of the multi-stage power amplifier or the output impedance matching of the power amplifier.

[0091] Further, the distance between the first coupling line 11 and the first sub-coupling line 131 and the third sub-coupling line 133 is substantially the same, and the distance between the second coupling line 12 and the second sub-coupling line 132 and the fourth sub-coupling line 134 is substantially the same, so that the distance between each primary stage coupling line and the two sub-coupling lines on the same layer is equal, and the coupling coefficients are close, which can improve the coupling degree of the balun.

[0092] As an implementation manner, the projection of the first coupling line 11 on the second metal layer L2 at least partially overlaps the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 at least partially overlaps the second sub-coupling line 132; and the projection of the third sub-coupling line 133 on the second metal layer L2 at least partially overlaps the fourth sub-coupling line 134. In this way, the distance between the first sub-coupling line and the first coupling line, the distance between the second sub-coupling line and the second coupling line, the distance between the third sub-coupling line and the first coupling line, and the distance between the fourth sub-coupling line and the second coupling line are close or equal, which can further improve the coupling degree of the balun.

[0093] For example, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps the second sub-coupling line 132; the projection of the third sub-coupling line 133 on the second metal layer L2 substantially overlaps the fourth sub-coupling line 134, at this time, the third sub-coupling line 133 and the first coupling line 131 can be connected in parallel with each other, the fourth sub-coupling line 134 and the second sub-coupling line 132 can also be connected in parallel with each other, for example, the first end of the third sub-coupling line 133 and the first end of the first sub-coupling line 131 can be connected through a connection line crossing the first coupling line 11, and then connected to the unbalanced end Unb; the second end of the third sub-coupling line 133 and the second end of the first sub-coupling line 131 are connected through another connection line crossing the first coupling line 11; similarly, the first end of the fourth sub-coupling line 134 and the first end of the second sub-coupling line 132 can be connected through a connection line crossing the second coupling line 12, and the second end of the fourth sub-coupling line 134 and the second end of the second sub-coupling line 132 are connected through another connection line crossing the second coupling line 12, in this way, the coupling degree of the balun is enhanced, and the area occupied by the balun is also saved.

[0094] For example, the connection line between the second end of the third sub-coupling line 133 and the second end of the first sub-coupling line 131 and the connection line between the first end of the fourth sub-coupling line 134 and the first end of the second sub-coupling line 132 can be the same connection line. For example, the second end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 can be connected through a conductive via hole via1 penetrating the first metal layer L1 and the second metal layer L2, the second end of the third sub-coupling line 133 and the first end of the fourth sub-coupling line 134 can be connected through another conductive via hole via2 penetrating the first metal layer L1 and the second metal layer L2, and the two conductive via holes via1 and via2 are connected through a connection line. In this way, the series connection of the third sub-coupling line 133 and the first sub-coupling line 131 and the series connection of the fourth sub-coupling line 134 and the second sub-coupling line 132 can be realized through the connection line, thereby optimizing the layout of the balun structure.

[0095] It should be noted that the above-mentioned connection lines can be arranged on other metal layers except the first metal layer L1 and the second metal layer L2, so as to avoid short-circuiting with the first coupling line or the second coupling line. The above-mentioned conductive via holes not only penetrate the first metal layer L1 and the second metal layer, but also penetrate the metal layer where the corresponding connection line is located, so that the connection line can be connected with the corresponding coupling line or sub-coupling line.

[0096] In the embodiments of the present application, since the distance between the metal layers is very close, the first coupling line 11 is coupled with the first sub-coupling line 131 and the third sub-coupling line 133 located in the first metal layer, and is also coupled between the second sub-coupling line 132 and the fourth sub-coupling line 134 located in another metal layer. Similarly, the second coupling line 12 is coupled with the second sub-coupling line 132 and the fourth sub-coupling line 134 located in the second metal layer, and is also coupled between the first sub-coupling line 131 and the third sub-coupling line 133 located in another metal layer. Therefore, the first coupling line 11 and the second coupling line 12 are substantially coupled with all the four sub-coupling lines of the third coupling line 133, and the coupling voltages generated by the first coupling line 11 and the second coupling line 12 are almost the same, so that the balance of the balun can be effectively improved. In addition, the first sub-coupling line 131 and the third sub-coupling line 133 are parallel in the first metal layer, and the second sub-coupling line 132 and the fourth sub-coupling line 134 are parallel in the second metal layer, which is equivalent to increasing the line width of the first sub-coupling line / second sub-coupling line and the third sub-coupling line / fourth sub-coupling line, so that the quality factor of the coupling line can be improved, thereby reducing the insertion loss of the balun.

[0097] It should be noted that, in the Figure 7b embodiments, since the second balance end Bal 2 led out from the first end P21 of the second coupling line 12 is also located in the second metal layer L2, in order to avoid the short circuit between the second sub-coupling line 132 and the second coupling line 12, the second sub-coupling line 132 is split into three segments 132a, 132b and 132c. Specifically, in the second metal layer, from the position of the conductive via Via1, the 132a is wound to the vicinity of the first end P21 of the second coupling line 12, then is jumped to the first metal layer L1 through a conductive via and is wound to the 132b, and then is jumped back to the second metal layer L2 through another conductive via and is continued to be wound to the 132c. At this time, the second sub-coupling line 132 only has a small segment jumped to other metal layers for avoiding the second coupling line 12, and the second coupling line 12 can be considered to be arranged in the second metal layer L2.

[0098] In one embodiment, as Figure 8As shown, the balun structure includes a first coupling line 11, a second coupling line 12 and a third coupling line 13, the third coupling line 13 includes a first sub-coupling line 131 and a second sub-coupling line 132, the first sub-coupling line 131 is disposed on the first metal layer L1 and coupled with the first coupling line 11, and the second sub-coupling line 132 is disposed on the second metal layer L2 and coupled with the second coupling line 12; a first end P11 of the first coupling line 11 is connected to the first balanced end Bal 1, and a second end P12 of the first coupling line 11 is grounded; a first end P21 of the second coupling line 12 is connected to the second balanced end Bal 2, and a second end P22 of the second coupling line 12 is grounded. A first end of the first sub-coupling line 131 and a first end of the second sub-coupling line 132 are respectively connected to the unbalanced end Unb, and a second end of the first sub-coupling line 131 and a second end of the second sub-coupling line 132 are respectively grounded.

[0099] In the embodiment, since the first sub-coupling line 131 and the second sub-coupling line 132 are in parallel relationship, the change rule of the voltage peak value is consistent, therefore, in the case that the first coupling line 11 and the second coupling line 12 are respectively coupled with one of the sub-coupling lines, the voltage peak values generated by the coupling of the first coupling line 11 and the second coupling line 12 are also almost consistent, thereby effectively improving the balance of the balun. On the other hand, when the balun structure is integrated in a chip, since the thickness of each layer in the chip is very thin and the distance between the metal layers is very close, the first coupling line 11 is coupled with the first sub-coupling line 131 located in the same first metal layer, and also coupled with the second sub-coupling line 132 located in another metal layer. Similarly, the second coupling line 12 is coupled with the second sub-coupling line 132 located in the same second metal layer, and also coupled with the first sub-coupling line 131 located in the first metal layer L1, therefore, the first coupling line 11 and the second coupling line 12 are substantially coupled with both sub-coupling lines of the third coupling line 133, and the coupling voltages generated by the two are almost consistent, thereby effectively improving the balance of the balun.

[0100] In the embodiment, since the first sub-coupling line 131 and the second sub-coupling line 132 are in parallel relationship, the change rule of the voltage peak value is consistent, therefore, in the case that the first coupling line 11 and the second coupling line 12 are respectively coupled with one of the sub-coupling lines, the voltage peak values generated by the coupling of the first coupling line 11 and the second coupling line 12 are also almost consistent, thereby effectively improving the balance of the balun. On the other hand, when the balun structure is integrated in a chip, since the thickness of each layer in the chip is very thin and the distance between the metal layers is very close, the first coupling line 11 is coupled with the first sub-coupling line 131 located in the same first metal layer, and also coupled with the second sub-coupling line 132 located in another metal layer. Similarly, the second coupling line 12 is coupled with the second sub-coupling line 132 located in the same second metal layer, and also coupled with the first sub-coupling line 131 located in the first metal layer L1, therefore, the first coupling line 11 and the second coupling line 12 are substantially coupled with both sub-coupling lines of the third coupling line 133, and the coupling voltages generated by the two are almost consistent, thereby effectively improving the balance of the balun.

[0101] The second end of the first sub-coupling line 131 and the second end of the second sub-coupling line 132 are both the second end S2 of the third coupling line 13. Alternatively, the two can be connected by a conductive via hole via2 penetrating the first metal layer L1 and the second metal layer L2, and then grounded by the same connecting line. Alternatively, the second end of the first sub-coupling line 131 and the second end of the second sub-coupling line 132 can also be grounded by different conductive via holes and lines respectively, and the present application does not limit this.

[0102] As an embodiment, the first coupling line 11, the second coupling line 12, the first sub-coupling line 131 and the second sub-coupling line 132 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape around the same axis. Further, the first coupling line 11, the second coupling line 12, the first sub-coupling line 131 and the second sub-coupling line 132 can be substantially parallel.

[0103] Exemplarily, the first coupling line 11, the second coupling line 12, the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 have substantially the same shape and the lengths of the lines are close to each other, so that the ratio of the inductance of the primary stage to the secondary stage is approximately 2:1.

[0104] Further, the distance between the first coupling line 11 and the first sub-coupling line 131 and the distance between the second coupling line 12 and the second sub-coupling line 132 are substantially the same, so that the spacing between each primary stage coupling line and the sub-coupling line in the same layer is equal, and the coupling coefficient is close, which can improve the coupling degree of the balun. For example, the projection of the first coupling line 11 on the second metal layer L2 at least partially overlaps the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 at least partially overlaps the second sub-coupling line 132, so that the spacing between the first coupling line 11 and the first sub-coupling line 131 and the spacing between the first coupling line 12 and the second sub-coupling line 132 are closer.

[0105] Exemplarily, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps with the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps with the second sub-coupling line 132, at this time, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 can be connected through the conductive via 1 penetrating the first metal layer L1 and the second metal layer L2, and then connected to the unbalanced end Unb through the connecting line; the second end of the first sub-coupling line 131 and the second end of the second sub-coupling line 132 can be connected through the conductive via 2 penetrating the first metal layer L1 and the second metal layer L2, and then grounded through the connecting line; the second end P12 of the first coupling line 11 and the second end P22 of the second coupling line 12 can also be connected through the conductive via 3 penetrating the first metal layer L1 and the second metal layer L2, and then grounded through the connecting line, thereby facilitating the wiring of the balun structure, and reducing the area occupied by the balun structure, and optimizing the layout of the layout.

[0106] Wherein, each of the above connecting lines can be arranged on other metal layers except the first metal layer L1 and the second metal layer L2, so as to avoid short-circuiting with the first coupling line or the second coupling line. Each of the above conductive vias not only penetrates the first metal layer L1 and the second metal layer, but also penetrates the metal layer where the corresponding connecting line is located, so that the connecting line can be connected with the corresponding coupling line or sub-coupling line.

[0107] In the embodiment, the first sub-coupling line 131 and the second sub-coupling line 132 are located in different metal layers and are connected in parallel with each other, which is equivalent to increasing the metal thickness of the first sub-coupling line 131 or the second sub-coupling line 132, improving the quality factor of the third coupling line, and thus reducing the insertion loss of the balun.

[0108] As an implementation manner, as Figure 9As shown, the third coupling line 13 further comprises a third sub-coupling line 133 and a fourth sub-coupling line 134, the third sub-coupling line 133 is disposed on the first metal layer L1 and is in parallel with the first sub-coupling line 131, and the fourth sub-coupling line 134 is disposed on the second metal layer L2 and is in parallel with the second sub-coupling line 132; wherein the first sub-coupling line 131 and the third sub-coupling line 133 are located on both sides of the first coupling line, and the second sub-coupling line 132 and the fourth sub-coupling line 134 are located on both sides of the second coupling line. In this way, the first coupling line 11 as the primary level can be coupled with both of the two sub-coupling lines (the first sub-coupling line 131 and the third sub-coupling line 133) as the secondary level, and similarly, the second coupling line 12 as the primary level can be coupled with both of the two sub-coupling lines (the third sub-coupling line 133 and the fourth sub-coupling line 134) as the secondary level, thereby enhancing the coupling degree between the primary level and the secondary level and improving the coupling coefficient of the balun. Moreover, the first sub-coupling line 131 is not only in parallel with the second sub-coupling line 132 of another metal layer, but also in parallel with the third sub-coupling line 133 of the same metal layer, which is equivalent to simultaneously increasing the metal thickness and the line width of the first sub-coupling line 131, further improving the quality factor of the third coupling line and reducing the insertion loss of the balun.

[0109] As an implementation manner, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps the second coupling line 12; the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps the second sub-coupling line 132, and the projection of the third sub-coupling line 133 on the second metal layer can substantially overlap the fourth sub-coupling line 134. Exemplarily, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 are connected by a conductive via 1, the second end of the first sub-coupling line 131 and the second end of the second sub-coupling line 132 are connected by a conductive via 2, the first end of the third sub-coupling line 133 and the first end of the fourth sub-coupling line 134 are connected by a conductive via 4, and the second end of the third sub-coupling line 133 and the second end of the fourth sub-coupling line 134 are connected by a conductive via 5, the conductive via 1 and the conductive via 4 are connected by a connection line, and the conductive via 2 and the conductive via 5 can be connected by another connection line, so as to realize the parallel connection of the first sub-coupling line 131, the second sub-coupling line 132, the third sub-coupling line 133 and the fourth sub-coupling line 134 through simple wiring, while further reducing the insertion loss of the balun, the layout of the balun structure can also be optimized.

[0110] In one embodiment, as shown in FIG. 1, the first coupling line 11 and the second coupling line 12 are disposed on the first metal layer L1 and the second metal layer L2, respectively, and the third coupling line 13 is disposed on the first metal layer L1 and the second metal layer L2. Figure 10 and Figure 11As shown, the balun structure includes a first coupling line 11, a second coupling line 12, a third coupling line 13, a fourth coupling line 14 and a fifth coupling line 15. Among them, the third coupling line 13 is a secondary coupling line, including a first sub-coupling line 131 located in the first metal layer L1 and a second sub-coupling line 132 located in the second metal layer L2. The first coupling line 11, the second coupling line 12, the fourth coupling line 14 and the fifth coupling line 15 are all primary coupling lines. The fourth coupling line 14 is in parallel with the first coupling line 11, both of which are located in the first metal layer L1 and distributed on both sides of the first sub-coupling line 131. The fifth coupling line 15 is in parallel with the second coupling line 12, both of which are located in the second metal layer L2 and distributed on both sides of the second sub-coupling line 132. Specifically, the first end of the fourth coupling line 14 is connected to the first end of the first coupling line 11, the second end of the fourth coupling line 14 is connected to the second end of the first coupling line 11, the first end of the fifth coupling line 15 is connected to the first end of the second coupling line 12, and the second end of the fifth coupling line 15 is connected to the second end of the second coupling line 12. The above connections can be realized through corresponding conductive vias, and specific details can be referred to the related description of the foregoing embodiments, which will not be described here.

[0111] As an implementation, as shown in Figure 10 The first sub-coupling line 131 and the second sub-coupling line 132 are in parallel with each other, for example, the first end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 can be connected through a conductive via via1 penetrating the first metal layer L1 and the second metal layer L2, and connected to the unbalanced end Unb through a connection line. The second end of the first sub-coupling line 131 and the second end of the second sub-coupling line 132 can be connected through another conductive via via2 penetrating the first metal layer L1 and the second metal layer L2, and connected to ground through another connection line. In this way, since the first sub-coupling line 131 and the second sub-coupling line 132 are in parallel, the voltage peak value change law of the two is basically the same, so the voltage peak value change law of the first sub-coupling line 131 and the second sub-coupling line 132 respectively coupled with one of the sub-coupling lines is also roughly the same, thereby improving the balance of the balun.

[0112] As an implementation, as shown in Figure 11As shown, the first sub-coupling line 131 and the second sub-coupling line 132 are connected in series, for example, the first end of the first sub-coupling line 131 is connected to the unbalanced end Unb, the second end of the first sub-coupling line 131 and the first end of the second sub-coupling line 132 are connected through a conductive via, and the second end of the second sub-coupling line 132 is grounded. In this embodiment, the balun structure can be integrated in a chip. Since the distance between the metal layers in the chip is very close, the first coupling line 11 and the fourth coupling line 14 are coupled with the first sub-coupling line 131 and the second sub-coupling line 132 in the same metal layer, and also have very good coupling between the first sub-coupling line 131 and the second sub-coupling line 132 in different metal layers. Similarly, the second coupling line 12 and the fifth coupling line 15 are coupled with the second sub-coupling line 132 and the first sub-coupling line 131 in the same metal layer, and also have very good coupling between the second sub-coupling line 132 and the first sub-coupling line 131 in different metal layers. Therefore, the first coupling line 11, the second coupling line 12, the fourth coupling line 14 and the fifth coupling line 15 are substantially coupled with both sub-coupling lines of the third coupling line 133, and the coupling voltages generated on the primary coupling lines are almost the same, thereby effectively improving the balance of the balun.

[0113] As an embodiment, the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15 and the plurality of sub-coupling lines of the third coupling line 13 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape around the same axis. Further, the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15 and the plurality of sub-coupling lines of the third coupling line 13 can be substantially parallel. For example, the distance between the first coupling line 11 and the fourth coupling line 14 and the first sub-coupling line 131 is substantially the same, and the distance between the second coupling line 12 and the fifth coupling line 15 and the second sub-coupling line 132 is substantially the same. In this way, the distance between each secondary sub-coupling line and the two primary coupling lines in the same layer is equal, the coupling coefficients are close, and the coupling degree of the balun can be further improved.

[0114] For example, the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15, the first sub-coupling line 131 and the second sub-coupling line 132 have substantially the same shape and similar lengths. If the first sub-coupling line 131 and the second sub-coupling line 132 are connected in parallel, the ratio of the inductance of the primary and secondary is substantially 2:1. If the first sub-coupling line 131 and the second sub-coupling line 132 are connected in series, the ratio of the inductance of the primary and secondary is substantially 1:1, which can be applied to the inter-stage impedance matching of a multi-stage power amplifier or the output impedance matching of a power amplifier.

[0115] Exemplarily, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps with the second coupling line 12, the projection of the fourth coupling line 14 on the second metal layer L2 substantially overlaps with the fifth coupling line 15, and the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps with the second sub-coupling line 132, so that the coupling degree between the primary coupling lines and the secondary sub-coupling lines of different metal layers can be enhanced, and the area occupied by the balun structure can be saved.

[0116] In the embodiment, the first sub-coupling line 131 of the secondary can be coupled with both the first coupling line 11 and the fourth coupling line 14, and the second sub-coupling line 132 of the secondary can be coupled with both the second coupling line 12 and the fifth coupling line 15, so that the coupling degree between the primary and the secondary of the balun can be improved, and the fourth coupling line 14 is in parallel with the first coupling line 11, which is equivalent to increasing the line width of the first coupling line 11, and the fifth coupling line 15 is in parallel with the second coupling line 12, which is equivalent to increasing the line width of the second coupling line 12, so that the quality factor of the first coupling line and the second coupling line can be improved, and the insertion loss of the balun can be reduced while improving the coupling degree.

[0117] In one embodiment, as shown in FIGS. 1 and 2, the balun structure of the present application comprises a first balanced end Bal1, a second balanced end Bal2 and an unbalanced end Unb, and further comprises a first coupling line 11, a second coupling line 12, a third coupling line 13, a fourth coupling line 14 and a fifth coupling line 15. Figure 12a and Figure 12b The first end P11 of the first coupling line 11 is connected to the first balanced end Bal1, and the second end P12 is used for grounding. The first end P21 of the second coupling line 12 is connected to the second balanced end Bal2, and the second end P22 is used for grounding. The first end S1 of the third coupling line 13 is connected to the unbalanced end Unb, and the second end S2 is used for grounding. The third coupling line 13 comprises a first sub-coupling line 131 arranged on the first metal layer L1 and a second sub-coupling line 132 arranged on the second metal layer L2. Specifically, the first coupling line 11, the second coupling line 12 and the first sub-coupling line 131 are all arranged on the first metal layer L1, and the first sub-coupling line 131 is sandwiched between the first coupling line 11 and the second coupling line 12. The fourth coupling line 14, the fifth coupling line 15 and the second sub-coupling line 132 are all arranged on the second metal layer L2, and the second sub-coupling line 132 is sandwiched between the fourth coupling line 14 and the fifth coupling line 15.

[0118] In the embodiment, the third coupling line 13 is a secondary coupling line, and the first sub-coupling line 131 and the second sub-coupling line 132 in the third coupling line 13 are in series. Exemplarily, the first end of the first sub-coupling line 131 is connected to the unbalanced end Unb, the second end of the first sub-coupling line 131 is connected to the first end of the second sub-coupling line 132, and the second end of the second sub-coupling line 132 is grounded.

[0119] In the embodiment, the first coupling line 11, the second coupling line 12, the fourth coupling line 14 and the fifth coupling line 15 are all main-stage coupling lines, and the fourth coupling line 14 is connected in parallel with the first coupling line 11, and the fifth coupling line 15 is connected in parallel with the second coupling line 12. Exemplarily, the first end of the fourth coupling line 14 is connected to the first end P11 of the first coupling line through the conductive via 4, and the second end of the fourth coupling line 14 is connected to the second end of the first coupling line through the conductive via 6; the first end of the fifth coupling line 15 is connected to the first end of the second coupling line through the conductive via 5, and the second end of the fifth coupling line 15 is connected to the second end of the second coupling line through the conductive via 7. Specifically, the above connections can be achieved through corresponding conductive vias, and specific reference can be made to the related description of the foregoing embodiments, which will not be described here again.

[0120] In the embodiment, the first coupling line 11 is connected in parallel with the fourth coupling line 14 on another metal layer, and the second coupling line 12 is connected in parallel with the fifth coupling line 15 on another metal layer, which is equivalent to increasing the metal thickness of the first coupling line 11 and the second coupling line 12, thereby improving the quality factor of the balun and reducing the insertion loss of the balun.

[0121] The balun structure of the embodiment can be integrated in a chip. Since the distance between different metal layers in the chip is very close, when the first coupling line 11 is coupled with the first sub-coupling line 131 on the same layer and the fourth coupling line 14 is coupled with the second sub-coupling line 132 on the same layer, the first coupling line 11 also has good coupling with the second sub-coupling line 132 on another layer, and the fourth coupling line 14 also has good coupling with the first sub-coupling line 131 on another layer, that is, the first coupling line 11 and the fourth coupling line 14 are coupled with the first sub-coupling line 131 and the second sub-coupling line 132; similarly, the second coupling line 12 and the fifth coupling line 15 are also coupled with the first sub-coupling line 131 and the second sub-coupling line 132. In other words, each of the first coupling line 11, the second coupling line 12, the fourth coupling line 14 and the fifth coupling line 15 is coupled with both of the two sub-coupling lines of the third coupling line 133, and the coupling voltages generated on each main-stage coupling line are almost consistent, thereby effectively improving the balance of the balun.

[0122] It should be noted that the embodiment is applicable not only to the scenario where the thickness of the first metal layer L1 is the same as the thickness of the second metal layer L2, but also to the scenario where the thickness of the first metal layer L1 is different from the thickness of the second metal layer L2.

[0123] Even if the thickness of the first metal layer L1 is different from the thickness of the second metal layer L2, resulting in different inductance of the first coupling line 11 and the fourth coupling line 14, and different inductance of the second coupling line 12 and the fifth coupling line 15, but since the first coupling line 11 and the fourth coupling line 14 are in parallel, and the second coupling line 12 and the fifth coupling line 15 are in parallel, the voltage generated on the different primary coupling lines can still maintain good consistency, so the balun structure can still maintain good balance.

[0124] Alternatively, the second end of the first coupling line 11 and the second end of the second coupling line 12 can be connected by a connection line across the first sub-coupling line 131 and grounded; or the second end P11 of the first coupling line 11 and the second end P22 of the second coupling line 12 can be respectively grounded by different connection lines, which is not limited in the present application. It should be noted that the above connection lines can be provided on other metal layers except the first metal layer L1 to avoid shorting with the first sub-coupling line 131. It should be noted that the second end of the first coupling line 11 and the second end of the second coupling line 12 can be directly grounded, or grounded through a capacitor, which is not limited in the present application.

[0125] As an embodiment, the first coupling line 11, the second coupling line 12 and the first sub-coupling line 131 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape around the same axis. Further, the first coupling line 11, the second coupling line 12 and the first sub-coupling line 131 can be substantially parallel, and the distance between the first coupling line 11 and the second coupling line 12 and the first sub-coupling line 131 is substantially equal, so that the coupling degree of the first coupling line 11 and the first sub-coupling line 131 is substantially equal to the coupling degree of the second coupling line 12 and the first sub-coupling line 131, which can further improve the balance of the balun structure.

[0126] As an embodiment, the width of the first coupling line 11 and the second coupling line 12 can be slightly smaller than the line width of the first sub-coupling line 131, or substantially the same as the line width of the first sub-coupling line 131, which can make the coupling degree of the balun structure better.

[0127] As an embodiment, the first coupling line 11, the second coupling line 12 and the first sub-coupling line 131 have substantially the same shape, for example, all are straight segments, L-shaped, U-shaped or a specific shape around the same axis. Further, the first coupling line 11, the second coupling line 12 and the first sub-coupling line 131 can be substantially parallel and have a length close to each other, so that the ratio of the inductance of the primary and the secondary is substantially 2:1.

[0128] In the embodiment, when the shapes of the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15, the first sub-coupling line 131 and the second sub-coupling line 132 are substantially the same, and the lengths of the traces are close, the ratio of the inductance of the primary stage to the inductance of the secondary stage is substantially 1:1, and the power amplifier can be applied to the inter-stage impedance matching of the multi-stage power amplifier or the output impedance matching of the power amplifier.

[0129] Optionally, each of the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15 and the sub-coupling lines of the third coupling line is in a straight line segment; or each of the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15 and the sub-coupling lines of the third coupling line surrounds the second axis, and the second axis is perpendicular to the first metal layer or the second metal layer.

[0130] Exemplarily, the projection of the first coupling line 11 on the second metal layer L2 at least partially overlaps the fourth coupling line 14; the projection of the second coupling line 12 on the second metal layer L2 at least partially overlaps the fifth coupling line 15; and the projection of the first sub-coupling line 131 on the second metal layer L2 at least partially overlaps the second sub-coupling line 132. Further, the projection of the first coupling line 11 on the second metal layer L2 substantially overlaps the fourth coupling line 14, the projection of the second coupling line 12 on the second metal layer L2 substantially overlaps the fifth coupling line 15, and the projection of the first sub-coupling line 131 on the second metal layer L2 substantially overlaps the second sub-coupling line 132, so as to strengthen the coupling degree between the primary coupling lines and the secondary sub-coupling lines of different metal layers, and save the area occupied by the balun structure.

[0131] In the embodiment, by arranging the first coupling line 11, the second coupling line 12, the fourth coupling line 14, the fifth coupling line 15, the first sub-coupling line 131 and the second sub-coupling line 132, the balance of the balun can be improved, the insertion loss of the balun can be reduced, and the adjustment of the transformation ratio of the balun can be realized according to the requirement.

[0132] As an embodiment, as shown in FIG. 1, a balun structure is provided, which comprises a first metal layer L1 and a second metal layer L2. Figure 12aAs shown, the first coupling line 11, the second coupling line 12, the third coupling line 13, the fourth coupling line 14, the first sub-coupling line 131 and the second sub-coupling line 132 are all continuous loops or segments, the second end of the first coupling line 11 and the second end of the second coupling line 12 are connected in series through the connecting line w3, and the second end of the fourth coupling line 14 and the second end of the fifth coupling line 15 are also connected in series through the connecting line w3. In order to avoid short-circuiting of the connecting line w3 with the first sub-coupling line 131 or the second sub-coupling line 132, the connecting line w3 needs to be arranged on a metal layer other than the first metal layer L1 and the second metal layer L2. At this time, the conductive via 6 and the conductive via 7 not only penetrate the first metal layer L1 and the second metal layer, but also penetrate the metal layer where the corresponding connecting line w3 is located, so that the connecting line w3 can realize the series connection of the first coupling line 11 and the second coupling line 12, and the series connection of the fourth coupling line 14 and the fifth coupling line 15.

[0133] In the present embodiment, since the first sub-coupling line 131 is located inside the first coupling line 11, and the second sub-coupling line 132 is located inside the fourth coupling line 14, in order to avoid short-circuiting of the first sub-coupling line 131 and the second sub-coupling line 132 with the first coupling line 11 and the fourth coupling line 14, when the unbalanced end Unb is led out from the first end of the first sub-coupling line 131, the first end of the first sub-coupling line 131 needs to be connected to a metal layer other than the first metal layer L1 and the second metal layer L2 through the conductive via 1, and the unbalanced end Unb is led out from the metal layer. Similarly, when the second end of the second sub-coupling line 132 is grounded, the second end of the second sub-coupling line 132 needs to be connected to a metal layer other than the first metal layer L1 and the second metal layer L2 through the conductive via 2, and the metal layer is grounded.

[0134] Also because the second coupling line 12 and the fifth coupling line 15 are respectively located inside the first sub-coupling line 131 and the second sub-coupling line 132, when the second balanced end Bal2 is led out from the second end of the second coupling line 12 and the second end of the fifth coupling line 15, the second end of the second coupling line 12 and the second end of the fifth coupling line 15 also need to be connected to a metal layer other than the first metal layer L1 and the second metal layer L2 through the conductive via 5, and the second balanced end Bal2 is led out from the metal layer.

[0135] As can be seen, in the present embodiment, the first coupling line 11, the second coupling line 12, the third coupling line 13, the fourth coupling line 14, the first sub-coupling line 131 and the second sub-coupling line 132 are all continuous loops or segments, making the wiring relatively simple and easy to implement, but the present embodiment needs to additionally occupy at least one metal layer to arrange the connecting line, so the cost is relatively high.

[0136] As another implementation, at least one of the sub-coupling lines 11, 12, 143 and 15 can be segmented and connected to another metal layer via conductive vias to avoid shorting with the first sub-coupling line 131 and the second sub-coupling line 132. This eliminates the need to add other metal layers to set the connecting lines, thereby reducing the number of metal layers occupied by the balun structure and thus reducing costs.

[0137] For example, such as Figure 12b As shown, the first coupling line 11 located in the first metal layer L1 is divided into two segments: coupling line segment 11a and coupling line segment 11b. The fourth coupling line 14 located in the second metal layer L2 is also divided into two segments: coupling line segment 14a and coupling line segment 14b. The projections of coupling line segment 11a and coupling line segment 14a in the direction perpendicular to the substrate overlap, and their two ends are connected in parallel through vias via4 and via6, respectively. The projections of coupling line segment 11b and coupling line segment 14b in the direction perpendicular to the substrate overlap, and their two ends are connected in parallel through vias via5 and via9, respectively. In this configuration, the second ends of coupling line segment 11a and coupling line segment 14a are connected to the inner side via conductive via 6, connecting line w4 located in the first metal layer L1, and conductive via 7, and are connected to the first end of the second coupling line 12 and the first end of the fifth coupling line 15. The second ends of the second coupling line 12 and the second ends of the fifth coupling line 15 are then connected to the outer side via conductive via 8, connecting line w5 located in the second metal layer L2, and conductive via 9, and are connected to the first ends of coupling line segment 11b and coupling line segment 14b, thereby realizing the series connection of the first coupling line 11 and the second coupling line 11, and the series connection of the fourth coupling line 14 and the fifth coupling line 15.

[0138] Furthermore, the first sub-coupling line 131 located in the first metal layer L1 and the second sub-coupling line 132 located in the second metal layer L2 are connected in series through a conductive via 3. Since the first sub-coupling line 131 is located outside the second coupling line 12, that is, outside the conductive via 7, and since the first end of the first sub-coupling line 131 is located between the conductive via 7 and the conductive vias 6 and 8, the connecting line w4 connected between the conductive vias 7 and 6, although located in the first metal layer L1, will not be short-circuited with the first sub-coupling line 131; similarly, the connecting line w5 connected between the conductive vias 8 and 9, although located in the second metal layer L2, will not be short-circuited with the second sub-coupling line 132.

[0139] Therefore, by means of the segmentation of the coupling lines and the arrangement of the conductive vias 6-9, each connection line can avoid the first coupling line 11 and the second coupling line 12 without occupying extra metal layers, thereby reducing the total number of metal layers occupied by the balun structure and reducing the cost.

[0140] In some embodiments, the balun structure can include M first primary coupling lines and M first secondary coupling lines, where M is a positive integer and M≥2. The M first primary coupling lines and the M first secondary coupling lines are arranged one by one on M metal layers, specifically, each first primary coupling line and the corresponding first secondary coupling line are arranged on the same metal layer and are coupled to each other. Optionally, the metal layer can be a metal layer of a chip or a metal layer of a package substrate.

[0141] In the present embodiment, the projection of any two first primary coupling lines on different metal layers on any metal layer has at least partial overlap, and the projection of any two first secondary coupling lines on different metal layers on any metal layer has at least partial overlap. In this way, since the spacing between the metal layers of the chip / packaging substrate is very small, and the positions of the M first primary coupling lines substantially overlap, and the positions of the M first secondary coupling lines also substantially overlap, for any one first primary coupling line, when the distance between it and the first secondary coupling line on the same metal layer is small enough to produce coupling, it can also produce coupling with the first secondary coupling line on the adjacent metal layer. Similarly, for any one first secondary coupling line, when the distance between it and the first primary coupling line on the same metal layer is small enough to produce coupling, it can also produce coupling with the first primary coupling line on the adjacent metal layer. This not only improves the coupling degree between the primary coupling lines and the secondary coupling lines, but also makes the voltage peaks produced by the coupling on different primary coupling lines closer, thereby improving the balance of the balun.

[0142] Exemplarily, the balun structure is integrated in a chip, and the metal layers are the metal layers inside the chip. Since the distance between the metal layers inside the chip is smaller than the layer spacing of the substrate, the coupling between the primary coupling lines and the secondary coupling lines on adjacent two metal layers is stronger, and therefore, integrating the balun structure in the chip can obtain better coupling degree and balance.

[0143] As an implementation, the length of each first primary coupling line is substantially the same as the length of each first secondary coupling line, for example, the difference between the length of any one first primary coupling line and the length of any one first secondary coupling line is not more than 10% of the length of the first primary coupling line. In this way, the coupling degree between the primary and the secondary can be enhanced, thereby improving the performance of the balun structure. In addition, it is also convenient to adjust the transformation ratio of the balun structure as needed.

[0144] In the embodiments of the present application, further, the connection relationship between the M first primary coupling lines and / or the connection relationship between the M first secondary coupling lines can be set according to the transformation ratio required by impedance matching.

[0145] As an implementation, when the primary-secondary transformation ratio of the balun structure required is M:N (M and N are both positive integers and M≥N≥2), M first primary coupling lines can be set in series, N first secondary coupling lines can be set in series, and the length of each coupling line (including the first primary coupling line and the first secondary coupling line) is substantially the same. In the case that the length of each coupling line is substantially the same, assuming that the inductance of each coupling line is substantially L, the inductance of the M first primary coupling lines in series is M*L, and the inductance of the N first secondary coupling lines in series is N*L, thus a balun structure with a primary-secondary transformation ratio of M:N can be obtained.

[0146] Exemplarily, (M-N+1) first secondary coupling lines of the M first secondary coupling lines can be connected in parallel to obtain an inductance of substantially L, and then (N-1) first secondary coupling lines are connected in parallel to obtain an inductance of L+(N-1)*L, so that the total inductance of the secondary side is N*L. Since the total inductance of the primary side is M*L, a balun structure with a primary-secondary transformation ratio of M:N can be obtained.

[0147] Alternatively, the (M-N+1) first secondary coupling lines can be selected arbitrarily from the M first secondary coupling lines. For example, the (M-N+1) first secondary coupling lines can be distributed on (M-N+1) continuous metal layers to facilitate the connection between different layers; or the (M-N+1) first secondary coupling lines and the (N-1) first secondary coupling lines can be arranged alternately on M metal layers, and the present application does not limit this.

[0148] As another implementation, when the primary-secondary transformation ratio of the balun structure required is N:M (M and N are both positive integers and M≥N≥2), N first primary coupling lines can be set in series, M first secondary coupling lines can be set in series, and the length of each coupling line (including the first primary coupling line and the first secondary coupling line) is substantially the same. In the case that the length of each coupling line is substantially the same, assuming that the inductance of each coupling line is substantially L, the inductance of the N first primary coupling lines in series is N*L, and the inductance of the M first secondary coupling lines in series is M*L, thus a balun structure with a primary-secondary transformation ratio of N:M can be obtained.

[0149] Exemplarily, (M-N+1) first primary coupling lines of the M first primary coupling lines can be connected in parallel to obtain an inductance of approximately L, and then (N-1) first primary coupling lines are connected in parallel to obtain an inductance of L+(N-1)*L, so that the total inductance of the primary side is N*L. Since the total inductance of the secondary side is M*L, the balun structure with a primary-to-secondary ratio of N:M is obtained.

[0150] Optionally, the (M-N+1) first primary coupling lines can be selected from the M first primary coupling lines. For example, the (M-N+1) first primary coupling lines can be distributed on (M-N+1) consecutive metal layers to facilitate connection between different layers, or the (M-N+1) first primary coupling lines and the (N-1) first primary coupling lines can be arranged on the M metal layers, and the application does not limit this.

[0151] Further, in order to ensure the balance of the balun structure, the M first primary coupling lines can be divided into two groups in series, each group including M / 2 first primary coupling lines. [(M-N) / 2+1] first primary coupling lines in each group are connected in parallel to obtain an inductance of approximately L, and then (N / 2-1) first primary coupling lines are connected in series to obtain an inductance of approximately N / 2*L. Then, the two groups of first primary coupling lines are connected in series to obtain an inductance of approximately N*L, realizing a primary-to-secondary ratio of approximately N:M. Wherein, M and N are multiples of 2.

[0152] Wherein, the two groups of first primary coupling lines can be symmetrically arranged to further improve the balance of the balun structure. Exemplarily, the M first primary coupling lines are distributed on M consecutive metal layers. In a top-down or bottom-up direction, the first primary coupling lines on the first M / 2 layers are divided into one group, and the first primary coupling lines on the last M / 2 layers are divided into another group, and the two groups of first primary coupling lines are symmetrically arranged with respect to the middle plane of the M / 2 layer and the (M / 2+1) layer. For example, when one group is [(M-N) / 2+1] first primary coupling lines in parallel and (N / 2-1) first primary coupling lines in series, the other group is [(M-N) / 2+1] first primary coupling lines in parallel and (N / 2-1) first primary coupling lines in series. Thus, the inductance of the two groups of first primary coupling lines remains consistent, improving the symmetry of the balun.

[0153] It should be noted that the two groups of first primary coupling lines respectively lead out one balanced end, for example, one leads out a first balanced end, and the other leads out a second balanced end.

[0154] In the embodiments of the present application, further, the number of the primary coupling lines on at least some of the metal layers can be greater than 1, for example, two primary coupling lines and one secondary coupling line are provided on at least some of the metal layers, and the secondary coupling line is sandwiched between the two primary coupling lines, so as to enhance the coupling degree between the primary and the secondary. Similarly, the number of the secondary coupling lines on at least some of the metal layers can also be greater than 1, for example, two secondary coupling lines and one primary coupling line are provided on at least some of the metal layers, and the primary coupling line is sandwiched between the two secondary coupling lines, so as to enhance the coupling degree between the primary and the secondary.

[0155] As an implementation, the balun structure further comprises J second primary coupling lines, where J is a positive integer and J≤M; the J second primary coupling lines are provided on the J metal layers respectively, and the projections of any two second primary coupling lines on any metal layer have at least partial overlap; on each metal layer provided with a second primary coupling line, the second primary coupling line is provided on both sides of the first secondary coupling line with the first primary coupling line.

[0156] Exemplarily, J=M, i.e., on each metal layer, the first secondary coupling line is provided between the first primary coupling line and the second primary coupling line, and the coupling degree and the balance of the balun structure can be further improved.

[0157] Optionally, the second primary coupling line on at least some of the metal layers is in parallel with the first primary coupling line on the same metal layer; and / or, the second primary coupling line on at least some of the metal layers is in series with the first primary coupling line on the same metal layer. As an implementation, the first primary coupling line and the second primary coupling line on each metal layer can be in parallel, so that the ratio of the total inductance of the primary coupling lines to the inductance of the secondary coupling line on the metal layer is approximately 1:1. It can be understood that in other implementations, when it is needed to adjust the transformation ratio of the balun structure, the first primary coupling line and the second primary coupling line on at least some of the metal layers can also be in series, so that the ratio of the total inductance of the primary coupling lines to the inductance of the secondary coupling line on the metal layer is approximately 2:1, thereby increasing the transformation ratio of the balun structure without affecting the balance of the balun structure.

[0158] For example, when it is required to adjust the turns ratio of the balun structure to be (M+t):N, the first primary coupling line on the t metal layers can be connected in series with the second primary coupling line, the first primary coupling line on the other (J-t) metal layers can be connected in parallel with the second primary coupling line, and the first primary coupling line on the other (M-J) metal layers can be connected in series with the first primary coupling line, so that the total inductance of the primary coupling lines is (M+t)*L. In addition, the first secondary coupling line on the (M-N+1) metal layers can be connected in parallel and then connected in series with the first secondary coupling line on the other (N-l) metal layers, so that the total inductance of the secondary coupling lines is N*L, thereby obtaining a balun structure with a turns ratio of (M+t):N. Here, t is a positive integer and t≤J.

[0159] As another embodiment, the balun structure further comprises K second secondary coupling lines, where K is a positive integer and K≤M; the K second secondary coupling lines are arranged one on each of the K metal layers, and the projections of any two second secondary coupling lines on the substrate have at least partial overlap; and on each metal layer on which a second secondary coupling line is arranged, the second secondary coupling line is arranged on both sides of the first primary coupling line with respect to the first secondary coupling line.

[0160] Exemplarily, K=M, i.e. on each metal layer, the first primary coupling line is arranged between the first secondary coupling line and the second secondary coupling line, and the coupling degree and the balance of the balun structure can be further improved.

[0161] Optionally, the second secondary coupling lines on at least some of the metal layers are connected in parallel with the first secondary coupling lines on the same metal layers, and / or the second secondary coupling lines on at least some of the metal layers are connected in series with the first secondary coupling lines on the same metal layers. As an embodiment, the second secondary coupling line on each metal layer can be connected in parallel with the first secondary coupling line on the same metal layer, so that the ratio of the total inductance of the primary coupling lines to the inductance of the secondary coupling lines on the metal layer is approximately 1:1. It can be understood that in other embodiments, when it is required to adjust the turns ratio of the balun structure, the first secondary coupling lines on at least some of the metal layers can be connected in series with the second secondary coupling lines, so that the ratio of the total inductance of the primary coupling lines to the inductance of the secondary coupling lines on the metal layer is approximately 1:2, thereby reducing the turns ratio of the balun structure without affecting the balance of the balun structure.

[0162] For example, when the turns ratio of the balun structure needs to be adjusted to N:(M+p), the first secondary coupling line on p metal layers can be connected in series with the second secondary coupling line, the first secondary coupling line on the other (K-p) metal layers can be connected in parallel with the second secondary coupling line, and the first secondary coupling line on the other (M-K) metal layers can be connected in series with the second secondary coupling line, so that the total inductance of the secondary coupling lines is (M+p)*L. In addition, the first primary coupling line on (M-N+1) metal layers can be connected in parallel and then connected in series with the first primary coupling line on the other (N-1) metal layers, so that the total inductance of the primary coupling lines is N*L, thereby obtaining a balun structure with a turns ratio of N:(M+p). Here, p is a positive integer and p≤K.

[0163] In the above various embodiments, as an implementation, when the primary and secondary of the balun are coils arranged around an axis, the number of bends of at least one of the primary coil and the secondary coil of the balun can be reduced to reduce the loss of the radio frequency signal. For example, as shown in FIG. 1, the shape of the balun structure is generally octagonal, and the first end P11 of the first coupling line 11 and the first end P21 of the second coupling line 12 are arranged on opposite two sides of the octagon, rather than being respectively led out from the same side of the octagon, so that the number of bends of the first coupling line 11 and the second coupling line 12 is respectively reduced from 8 to 6, thereby effectively reducing the loss of the radio frequency signal. Figure 13

[0164] Further, when the first balance end Bal 1 and the second balance end Bal 2 are respectively led out from the first end P11 of the first coupling line 11 and the first end P21 of the second coupling line 12, the first balance end Bal 1 is sequentially arranged along the extension direction of the first coupling line 11 at the first end P11, and the second balance end Bal 2 is sequentially arranged along the extension direction of the second coupling line 12 at the first end P21, which can reduce the loss of the radio frequency signal when the radio frequency signal is output or input from the first balance end Bal 1 and the second balance end Bal 2.

[0165] Further, the metal area of the first balance end Bal 1 and the second balance end Bal 2 can be increased, for example, the width of the first balance end Bal 1 and the second balance end Bal 2 is greater than the line width of the first coupling line 11 and the second coupling line 12, which can further reduce the loss of the radio frequency signal when the radio frequency signal is output or input from the first balance end Bal 1 and the second balance end Bal 2.

[0166] For example, in the above various embodiments, when the balun structure is applied to the inter-stage impedance matching of a multi-stage power amplifier, the balun structure can be integrated with the power amplification circuits of the front and rear stages in the same chip, at this time, the coupling lines and the sub-coupling lines in the balun structure can be arranged in the form of coils around an axis to reduce the occupation of the chip area and avoid the chip having an excessively large aspect ratio. ​

[0167] Exemplarily, in the above various embodiments, when the balun structure is applied to the output impedance matching of the power amplifier, the balun structure can be arranged on the substrate of the radio frequency front-end module together with the chip integrated with the power amplification circuit and connected through the circuit on the substrate. Since the space on the substrate is more sufficient than the space in the chip, the coupling lines and the sub-coupling lines in the balun structure can be arranged in straight segments to reduce the insertion loss of the balun. Understandably, when the balun structure is applied to the output impedance matching of the multi-stage power amplifier, the balun structure can also be integrated in the same chip with the power amplification circuit of the previous stage for the consideration of area saving. At this time, the coupling lines and the sub-coupling lines in the balun structure can be arranged in coil shape around an axis.

[0168] Exemplarily, in the above various embodiments, the line widths of the coupling lines and the sub-coupling lines can be set to be similar or substantially the same to improve the coupling degree of the balun.

[0169] The second aspect of the present application provides a power amplifier, such as Figure 2 , Figure 3 As shown in the figure, the power amplifier 202 includes a first power amplification circuit PA1, a second power amplification circuit PA2, and a balun structure according to any of the above embodiments. The first balanced end Bal 1 of the balun structure is connected to the output end or the input end of the first power amplification circuit PA1, and the second balanced end Bal 2 of the balun structure is connected to the output end or the input end of the second power amplification circuit PA2.

[0170] As an implementation manner, the power amplifier includes a multi-stage power amplification circuit, and the balun structure is an inter-stage balun of the power amplifier. As shown in the figure, the power amplifier further includes a third power amplification circuit PA3. The output end of the third power amplification circuit PA3 is connected to the unbalanced end Unb of the balun structure. The first balanced end Bal 1 of the balun structure is connected to the input end of the first power amplification circuit PA1, and the second balanced end Bal 2 of the balun structure is connected to the input end of the second power amplification circuit PA1. Figure 4

[0171] Among them, the third power amplification circuit PA3 is a single-ended power amplification circuit, and the first power amplification circuit PA1 and the second power amplification circuit PA2 constitute a differential power amplification circuit. The balun structure is used to convert the unbalanced signal output by the single-ended power amplification circuit into the balanced signal required by the differential power amplification circuit, and realize the impedance matching between the single-ended power amplification circuit of the previous stage and the differential power amplification circuit of the subsequent stage.

[0172] ​The power amplifier circuit can be an amplifier circuit composed of at least one power amplifier transistor. For example, the power amplifier transistor can be any type of transistor such as a bipolar junction transistor, a metal-oxide semiconductor field effect transistor, etc. Illustratively, the power amplifier transistor is a heterojunction transistor implemented using a GaAs process. In at least one implementation, the power amplifier transistor is an NPN transistor. Illustratively, the first power amplifier circuit PA1, the second power amplifier circuit PA2, the third power amplifier circuit PA3, and the above-described balun structure are integrated in the same chip, for example, in a first chip. In this case, each of the coupling lines and the sub-coupling lines in the balun structure is arranged in a coil shape around an axis, which can reduce the occupation of the chip area and avoid an excessively large aspect ratio of the chip.

[0173] The third aspect of the present application provides a radio frequency front-end module. The radio frequency front-end module includes a substrate and a first chip disposed on the substrate. The first chip integrates the balun structure or the power amplifier of any of the above-described embodiments.

[0174] In some embodiments, the radio frequency front-end module can further include a radio frequency switch, a low noise amplifier, a filter, a duplexer, etc., which can be integrated into one module, thereby improving the integration and performance and miniaturizing the volume.

[0175] Specifically, the radio frequency front-end module can be applied to a communication device such as a smart phone, a tablet computer, a smart watch, etc. The radio frequency front-end module is, for example, a radio frequency front-end module applied to a communication device such as LTE (Long Term Evolution, LTE for short) and 5G (5th Generation Mobile Communication Technology).

[0176] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the same. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that the technical solutions described in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features. Such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A balun structure comprising a first balanced terminal, a second balanced terminal and an unbalanced terminal, characterized in that, The balun structure further comprises a first coupling line, a second coupling line and a third coupling line; a first end of the first coupling line is connected to the first balanced end, a first end of the second coupling line is connected to the second balanced end, and the first coupling line and the second coupling line are connected in series between the first balanced end and the second balanced end; a first end of the third coupling line is connected to the unbalanced end, and a second end of the third coupling line is used for grounding; wherein the first coupling line is arranged on a first metal layer, the second coupling line is arranged on a second metal layer, and the first metal layer and the second metal layer are different metal layers; the third coupling line comprises two groups of parallel sub-coupling lines, and the first coupling line and the second coupling line are coupled to one group of the two groups of parallel sub-coupling lines respectively, and the number of each group of sub-coupling lines is at least one.

2. The balun structure according to claim 1, wherein the third coupling line comprises a first sub-coupling line, a second sub-coupling line, a third sub-coupling line and a fourth sub-coupling line; the first sub-coupling line and the third sub-coupling line are arranged on the first metal layer and are coupled to at least the first coupling line, and the second sub-coupling line and the fourth sub-coupling line are arranged on the second metal layer and are coupled to at least the second coupling line; a first end of the first sub-coupling line and a first end of the second sub-coupling line are connected to the unbalanced end, a first end of the third sub-coupling line is connected to a second end of the first sub-coupling line, and a second end of the third sub-coupling line is grounded; a first end of the fourth sub-coupling line is connected to a second end of the second sub-coupling line, and a second end of the fourth sub-coupling line is grounded.

3. The balun structure of claim 2, wherein, the first sub-coupling line and the third sub-coupling line are located on two sides of the first coupling line respectively; the second sub-coupling line and the fourth sub-coupling line are located on two sides of the second coupling line respectively.

4. The balun structure of claim 1, wherein the third coupling line comprises a first sub-coupling line, a second sub-coupling line, a third sub-coupling line and a fourth sub-coupling line; a first end of the first sub-coupling line is connected to the unbalanced end, a second end of the first sub-coupling line is connected to a first end of the second sub-coupling line, and a second end of the second sub-coupling line is grounded; a first end of the third sub-coupling line is connected to the unbalanced end, a second end of the third sub-coupling line is connected to a first end of the fourth sub-coupling line, and a second end of the fourth sub-coupling line is grounded; a first end of the fourth sub-coupling line is connected to the first end of the second sub-coupling line, and a second end of the fourth sub-coupling line is connected to the second end of the second sub-coupling line; wherein the first sub-coupling line and the third sub-coupling line are arranged on the first metal layer and located on two sides of the first coupling line, and the second sub-coupling line and the fourth sub-coupling line are arranged on the second metal layer and located on two sides of the second coupling line.

5. The balun structure of claim 4, wherein, the second end of the first sub-coupling line and the first end of the second sub-coupling line are connected through a conductive via hole, and the second end of the third sub-coupling line and the first end of the fourth sub-coupling line are connected through another conductive via hole.

6. The balun structure of claim 1, wherein: the third coupling line comprises a first sub-coupling line and a second sub-coupling line, the first sub-coupling line is disposed on the first metal layer and coupled with the first coupling line, and the second sub-coupling line is disposed on the second metal layer and coupled with the second coupling line; a first end of the first sub-coupling line and a first end of the second sub-coupling line are connected to the unbalanced terminal, and a second end of the first sub-coupling line and a second end of the second sub-coupling line are grounded.

7. The balun structure of claim 6, wherein, the third coupling line further comprises a third sub-coupling line and a fourth sub-coupling line, the third sub-coupling line is disposed on the first metal layer and in parallel with the first sub-coupling line, and the fourth sub-coupling line is disposed on the second metal layer and in parallel with the second sub-coupling line; wherein the first sub-coupling line and the third sub-coupling line are located on two sides of the first coupling line, and the second sub-coupling line and the fourth sub-coupling line are located on two sides of the second coupling line.

8. The balun structure of claim 2 or 4 or 7, wherein: a projection of the first coupling line on the second metal layer at least partially overlaps with the second coupling line; a projection of the first sub-coupling line on the second metal layer at least partially overlaps with the second sub-coupling line; a projection of the third sub-coupling line on the second metal layer at least partially overlaps with the fourth sub-coupling line.

9. The balun structure of claim 1, wherein, the third coupling line comprises a first sub-coupling line and a second sub-coupling line in parallel, the first sub-coupling line is disposed on the first metal layer, and the second sub-coupling line is disposed on the second metal layer; and the balun structure further comprises: a fourth coupling line, a first end of which is connected to a first end of the first coupling line, and a second end of which is connected to a second end of the first coupling line; a fifth coupling line, a first end of which is connected to a first end of the second coupling line, and a second end of which is connected to a second end of the second coupling line; wherein the fourth coupling line is located on the first metal layer, and the fourth coupling line and the first coupling line are respectively located on two sides of the first sub-coupling line; the fifth coupling line is located on the second metal layer, and the fifth coupling line and the second coupling line are respectively located on two sides of the second sub-coupling line.

10. The balun structure of claim 9, wherein: a projection of the first coupling line on the second metal layer at least partially overlaps with the second coupling line; a projection of the first sub-coupling line on the second metal layer at least partially overlaps with the second sub-coupling line; 11. The balun structure according to any of claims 2-7 and 9-10, characterized by a projection of the fourth coupling line on the second metal layer at least partially overlaps with the fifth coupling line.

12. The balun structure according to any one of claims 2-7 and 9-10, characterized by each of the sub-coupling lines of the first coupling line, the second coupling line and the third coupling line is a straight line segment.

13. The balun structure of claim 1, wherein, each of the sub-coupling lines of the first coupling line, the second coupling line and the third coupling line is disposed around an axis, and the axis is perpendicular to the first metal layer or the second metal layer. the third coupling line is disposed on a third metal layer, and the third metal layer is located between the first metal layer and the second metal layer.

14. A balun structure comprising a first balanced terminal, a second balanced terminal and an unbalanced terminal, characterized in that, The balun structure is integrated in a chip, and further comprises a first coupling line, a second coupling line, a third coupling line, a fourth coupling line and a fifth coupling line: A first end of the first coupling line is connected to the first balanced end, a first end of the second coupling line is connected to the second balanced end, the first coupling line and the second coupling line are connected in series between the first balanced end and the second balanced end, the fourth coupling line is connected in parallel with the first coupling line, and the fifth coupling line is connected in parallel with the second coupling line; The third coupling line comprises at least a first sub-coupling line and a second sub-coupling line, a first end of the first sub-coupling line is connected to the unbalanced end, a second end of the first sub-coupling line is connected to a first end of the second sub-coupling line, and a second end of the second sub-coupling line is grounded; The first sub-coupling line, the first coupling line and the second coupling line are arranged on a first metal layer, and the first sub-coupling line is arranged between the first coupling line and the second coupling line; The second sub-coupling line, the fourth coupling line and the fifth coupling line are arranged on a second metal layer, and the second sub-coupling line is arranged between the fourth coupling line and the fifth coupling line.

15. The balun structure of claim 14, wherein, The first coupling line, the second coupling line, the fourth coupling line, the fifth coupling line and each sub-coupling line of the third coupling line are arranged in a straight line segment; or The first coupling line, the second coupling line, the fourth coupling line, the fifth coupling line and each sub-coupling line of the third coupling line are arranged around an axis, and the axis is perpendicular to the first metal layer or the second metal layer.

16. The balun structure of claim 14 or 15, wherein, A projection of the first coupling line on the second metal layer at least partially overlaps the fourth coupling line; A projection of the second coupling line on the second metal layer at least partially overlaps the fifth coupling line; A projection of the first sub-coupling line on the second metal layer at least partially overlaps the second sub-coupling line.

17. A balun structure, characterized by M first primary coupling lines and M first secondary coupling lines are arranged on M metal layers in one-to-one correspondence, and the first primary coupling line and the first secondary coupling line on the same metal layer are coupled, and the first primary coupling line is also coupled with the first secondary coupling line on the adjacent metal layer; The projections of any two first primary coupling lines on different metal layers on any of the metal layers at least partially overlap; The projections of any two first secondary coupling lines on different metal layers on any of the metal layers at least partially overlap; M is a positive integer and M≥2, and N is a positive integer and N≤M; wherein: The M first primary coupling lines are connected in series; (M-N+1) first secondary coupling lines are connected in parallel and connected in series with another (N-1) first secondary coupling lines; or The M first secondary coupling lines are connected in series; (M-N+1) first primary coupling lines are connected in parallel and connected in series with another (N-1) first primary coupling lines; or M first primary coupling lines are connected in series; M first primary coupling lines are divided into two groups connected in series, each group comprising M / 2 first primary coupling lines, and [ (M-N) / 2+1] first primary coupling lines in each group are connected in parallel and connected in series with another (N / 2-1) first primary coupling lines; M and N are both multiples of 2.

18. The balun structure of claim 17, wherein, The two groups of first primary coupling lines are symmetrically arranged.

19. The balun structure according to any of claims 17-18, characterized by The balun structure further comprises J second primary coupling lines, wherein J is a positive integer and J≤M; J second primary coupling lines are arranged one by one on J metal layers, and the projections of any two second primary coupling lines on any metal layer have at least partial overlap; On each metal layer provided with the second primary coupling line, the second primary coupling line is arranged on both sides of the first primary coupling line.

20. The balun structure of claim 19, wherein, The second primary coupling line on at least part of the metal layer is connected in parallel with the first primary coupling line on the same metal layer; and / or, the second primary coupling line on at least part of the metal layer is connected in series with the first primary coupling line on the same metal layer.

21. The balun structure of any of claims 17-18, wherein, The balun structure further comprises K second secondary coupling lines, wherein K is a positive integer and K≤M; K second secondary coupling lines are arranged one by one on K metal layers, and the projections of any two second secondary coupling lines on any metal layer have at least partial overlap; On each metal layer provided with the second secondary coupling line, the second secondary coupling line is arranged on both sides of the first primary coupling line.

22. The balun structure of claim 21, wherein, The second secondary coupling line on at least part of the metal layer is connected in parallel with the first secondary coupling line on the same metal layer, and / or the second secondary coupling line on at least part of the metal layer is connected in series with the first secondary coupling line on the same metal layer.

23. A power amplifier, characterized by The power amplifier comprises a first power amplifier circuit, a second power amplifier circuit and the balun structure according to any one of claims 1-22, wherein the first balanced end of the balun structure is connected to the output end or the input end of the first power amplifier circuit, and the second balanced end of the balun structure is connected to the output end or the input end of the second power amplifier circuit.

24. The power amplifier of claim 23, wherein, The power amplifier further comprises a third power amplifier circuit, wherein the output end of the third power amplifier circuit is connected to the unbalanced end of the balun structure, the first balanced end of the balun structure is connected to the input end of the first power amplifier circuit, and the second balanced end of the balun structure is connected to the input end of the second power amplifier circuit.

25. A radio frequency front end module, comprising: The radio frequency front end module comprises a substrate and a first chip arranged on the substrate, and the first chip is integrated with the balun structure according to any one of claims 1-22 or the power amplifier according to any one of claims 23-24.

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