Coupler and radio frequency front-end module

Abstract

The invention provides a coupler. The coupler comprises an input port; an output port; a coupling port; an isolation port; one end of the main line is connected with the input port, and the other end of the main line is connected with the output port; one end of the coupling line is connected with the coupling port, and the other end of the coupling line is connected with the isolated port; the first end of the switchable branch circuit is connected with the isolation port, the second end of the switchable branch circuit is grounded, the switchable branch circuit comprises a resistor branch circuit and at least one group of capacitor branch circuits which are connected in parallel, the resistor branch circuit comprises a first resistor, and each capacitor branch circuit comprises a capacitor and a switch; by changing the capacitance value of the capacitor connected to the isolation port of the coupler, the working bandwidth of the coupler is widened, so that the application requirement of broadband frequency is met.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency technology, and particularly to a coupler and a radio frequency front-end module. Background Art

[0002] A coupler is a device used to transfer high-frequency signals from one circuit to another. Its main function is to transfer high-frequency signals in one circuit to another circuit while maintaining signal stability and accuracy. The working principle of the coupler is based on the principle of electromagnetic induction, and it uses the interaction of electromagnetic fields to transfer signals. The main components of the coupler are two circuits, and they transfer signals through the interaction of electromagnetic fields. One of the circuits is called the "main circuit", and the other circuit is called the "slave circuit". The high-frequency signal in the main circuit is transferred to the slave circuit through the action of the electromagnetic field, thereby realizing signal transmission. The working principle of the coupler includes: the high-frequency signal in the main circuit is transferred to the slave circuit through the action of the electromagnetic field. The high-frequency signal in the slave circuit is excited, thereby generating a reverse electromagnetic field. The reverse electromagnetic field interacts with the high-frequency signal in the main circuit, thereby generating a new electromagnetic field. The new electromagnetic field transfers the signal back to the main circuit, thereby realizing signal transmission. The function of the coupler is to transfer high-frequency signals in one circuit to another circuit while maintaining signal stability and accuracy. It can be used in many different applications, such as wireless communication, radar systems, medical devices, etc. Traditional couplers have a large occupied area due to the complex circuit design of the isolation end and cannot be applied to the circuit design of miniaturized wideband. Therefore, a new circuit design is needed to make the produced chip have a smaller area and stronger performance. Summary of the Invention

[0003] The object of the present invention is to provide a coupler to solve the problem that the coupler cannot take into account both area and performance at the same time.

[0004] A coupler includes: an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, the first end of the switchable branch is connected to the isolation port, and the second end is grounded. The switchable branch includes a resistor branch and at least one group of capacitor branches connected in parallel. The resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch.

[0005] Preferably, the first resistor branch further includes a first compensation capacitor, and the first compensation capacitor is connected in parallel with the resistor of the first resistor branch, and / or, the capacitor branch further includes a second compensation capacitor, and the second compensation capacitor is connected in parallel with the capacitor of the capacitor branch.

[0006] Preferably, the at least one capacitive branch includes a first capacitive branch and a second capacitive branch, and the capacitance value of the first capacitive branch is less than that of the second capacitive branch;

[0007] If the coupler operates in the first frequency band, the first resistance branch is turned on, and the first capacitive branch and the second capacitive branch are both turned off;

[0008] If the coupler operates in the second frequency band, the first resistance branch and the first capacitive branch are turned on, and the second capacitive branch is turned off;

[0009] If the coupler operates in the third frequency band, the first resistance branch and the second capacitive branch are turned on, and the first capacitive branch is turned off;

[0010] If the coupler operates in the first frequency band, the first resistance branch, the first capacitive branch and the second capacitive branch are all turned on.

[0011] Wherein, the first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the third frequency band is greater than the first frequency band.

[0012] Preferably, if the operating frequency band of the coupler is in the range of [1.42 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 2.5 pF].

[0013] Preferably, if the operating frequency band of the coupler is in the range of [1.42 GHz, 1.5 GHz], the capacitance value range presented by the switchable branch is [1.2 pF, 2.5 pF];

[0014] If the operating frequency band of the coupler is in the range of [1.71 GHz, 2.1 GHz], the capacitance value range presented by the switchable branch is [0.5 pF, 1.2 pF];

[0015] If the operating frequency band of the coupler is in the range of [2.3 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 0.5 pF].

[0016] Preferably, the coupler further includes a third compensation capacitor. The capacitive branch and the first resistance branch are connected in parallel and then connected to the first end of the third compensation capacitor, and the second end of the third compensation capacitor is grounded.

[0017] Preferably, the capacitance value range of the third compensation capacitor is [0.1 pF, 1 pF].

[0018] Preferably, the resistance branch further includes a switch connected in series with the first resistance.

[0019] A radio frequency front-end module includes a substrate, a first chip disposed on the substrate, and a coupler disposed on the first chip. The coupler includes: an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, a first end of the switchable branch is connected to the isolation port, and a second end is grounded. The switchable branch includes a resistor branch connected in parallel and at least one group of capacitor branches. The resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch.

[0020] Preferably, the first chip includes a first metal layer, the coupling line includes a first coupling coil segment, the first coupling coil segment and the main line are relatively arranged, and the first coupling coil segment is wound to form a first region. Among them, the switchable branch is located in the first region.

[0021] Preferably, at least one group of the capacitor branches and the resistor branch are arranged in sequence in the first region in a direction away from the main line, and the resistor branch is arranged in the central region of the first region.

[0022] Preferably, the first capacitor branch, the resistor branch, and the second capacitor branch are arranged in sequence in a direction away from the main line.

[0023] Preferably, the first chip further includes a first metal layer and a second metal layer disposed adjacent to each other. The first coupling coil segment and the main line are located in the first metal layer. The coupling line further includes a first coupling line portion, the first coupling line portion is disposed in the second metal layer, the first coupling line portion is connected to the first coupling coil segment through a via hole, and the first coupling line portion and the main line overlap at least partially in the longitudinal direction.

[0024] In this embodiment, by adopting a plurality of parallel capacitor branches, the capacitance value of the capacitor connected to the isolation port of the coupler is changed. For a traditional coupler, by changing the capacitance value of the capacitor connected to the isolation port of the coupler, the working bandwidth of the coupler is broadened, so that the coupler is more widely used, meeting the application requirements of broadband frequency. And the coupler in the embodiment does not additionally increase the occupied area while broadening the working bandwidth of the coupler, realizing the miniaturized design of the coupler. Description of the Drawings

[0025] The drawings here are incorporated into the specification and form a part of this specification, indicating the embodiments that conform to the present invention, and are used together with the specification to explain the principles of the present invention.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic diagram of a circuit structure of the coupler of the present invention;

[0028] Figure 2 It is another schematic diagram of a circuit structure of the coupler of the present invention;

[0029] Figure 3 It is another schematic diagram of a circuit structure of the coupler of the present invention;

[0030] Figure 4 It is another schematic diagram of a circuit structure of the coupler of the present invention;

[0031] Figure 5 It is another schematic diagram of a circuit structure of the coupler of the present invention;

[0032] Figure 6 It is another schematic diagram of a circuit structure of the coupler of the present invention;

[0033] Figure 7 It is another schematic diagram of a circuit structure of the coupler of the present invention. Detailed implementation manners

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0036] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] In the present invention, multiple parallel capacitor branches are provided between the isolation terminal of the coupler and the ground to adjust the capacitance value of the isolation terminal of the coupler, so that the coupler can ensure the stability and accuracy of signal transmission in a relatively wide operating frequency band.

[0038] Embodiment 1

[0039] This application provides a coupler 100, as Figures 1 to 7 shown, including:

[0040] An input port 1, an output port 2, a coupling port 3, and an isolation port 4,

[0041] A main line 10 extending between the input port 1 and the output port 2, and a coupling line 30 extending between the coupling port 3 and the isolation port 4,

[0042] A switchable branch, the first end of the switchable branch is connected to the isolation port 4, the second end is grounded, and the switchable branch includes a parallel-connected resistance branch and at least one capacitor branch. The resistance branch includes a first resistor R1, and each capacitor branch includes a capacitor and a switch.

[0043] Among them, directivity is a measure or quality factor of the ability of a coupler to distinguish incident waves and reflected waves in a transmitting system. The quality of the directivity of a coupler depends on the electric field component and magnetic field component in the coupling circuit. When the components generated by these two sources are balanced, the directivity is optimal. The values of the electric field component and magnetic field component depend on the coupling capacitance and inductance on the coupling plate. Coupler directivity calculation formula: D(dB) = ISO(dB) - C(dB), where D is the directivity of the coupler; ISO is the isolation of the coupler; C is the coupling of the coupler.

[0044] Among them, the impedance of the capacitor in an AC circuit is the capacitive reactance Xc, and the calculation formula is Xc = 1 / (ωC) = 1 / (2πfC), where f is the frequency in Hz, ω = 2πf is the angular frequency in 1 / s. In the RF circuit where the coupler is located, generally, the higher the frequency, the smaller the required capacitance value, and the lower the frequency, the larger the required capacitance value. The capacitive reactance value Xc is an important value to ensure the isolation and directivity of the coupler. In a case of a fixed requirement, for example, assuming that the directivity of the coupler is not less than a preset value (such as 18 dB), the range of Xc can be determined. The higher the frequency, the larger the ω value, and at this time, the capacitance value C is smaller, so that the product ωC of these two values can ensure that it is within a certain fixed value range to ensure that the capacitive reactance value Xc meets the actual requirements.

[0045] In the RF front-end system, the coupler usually needs to transmit signals of multiple different frequency bands. If different couplers are required to transmit the signals of each frequency band, the system cost and area will increase. Therefore, in this embodiment, a coupler capable of operating in a wide frequency band range is designed, which can save the occupied area and cost while ensuring performance. Specifically, in this application, a switchable branch is connected between the isolation port of the coupled line and the ground. The switchable branch includes a resistor branch connected in parallel and at least one group of capacitor branches. The resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch; by switching the state of the capacitor branch, the capacitance value presented by the switchable branch can be changed to change the capacitance value of the isolation degree of the coupler; thus, the demand for coupling capacitance under different frequency bands can be met, and the directivity of the coupler can be further optimized.

[0046] In this embodiment, multiple parallel capacitor branches are adopted to change the capacitance value of the capacitor connected to the isolation port of the coupler. For a traditional coupler, by changing the capacitance value of the capacitor connected to the isolation port of the coupler, the operating bandwidth of the coupler is broadened, so that the coupler is more widely used, meeting the application requirements of the broadband frequency. Moreover, the coupler in the embodiment can not only adjust the bandwidth but also adjust the standing wave ratio, enabling the coupler to better match the line and reduce power loss.

[0047] In this embodiment, a coupler includes an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, a first end of the switchable branch is connected to the isolation port, and a second end is grounded. The switchable branch includes a resistor branch and at least one group of capacitor branches connected in parallel. The resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch; by connecting a switchable branch between the isolation port of the coupling line and the ground, the requirement for the coupling capacitor at different frequency bands can be met, and thus the directivity of the coupler can be optimized.

[0048] In a specific embodiment, the first resistor branch further includes a first compensation capacitor C23, the first compensation capacitor C23 is connected in parallel with the resistor R1 of the first resistor branch, and / or, the capacitor branch further includes a second compensation capacitor, and the second compensation capacitor is connected in parallel with the capacitor of the capacitor branch.

[0049] As Figure 5 shown, the first resistor branch further includes a first compensation capacitor C23, the first compensation capacitor C23 is connected in parallel with the resistor of the first resistor branch, and / or, the capacitor branch further includes a second compensation capacitor (such as Figure 5 the compensation capacitor C21 and the compensation capacitor C22 shown), and the second compensation capacitor is connected in parallel with the capacitor of the capacitor branch

[0050] The first resistor branch in this embodiment further includes a first compensation capacitor connected in parallel with the resistor, and / or, at least one capacitor branch further includes a second compensation capacitor connected in parallel with the capacitor; by adjusting the capacitance values of the first compensation capacitor and the second compensation capacitor, the isolation and directivity of the coupler can be improved well; thereby improving the directivity and isolation of the coupler in a wide frequency band (especially in two frequency points with a large span, for example, in the frequency band range of [1.42 GHz, 2.69 GHz]).

[0051] In at least one embodiment, the first compensation capacitor and the second compensation capacitor can be equivalent capacitors formed by the ground (GND) of the first metal layer on the substrate directly under the chip and the metal on the chip, or can be equivalent capacitors formed by the ground (GND) of the first metal layer on the substrate and the ground (GND) of the second metal layer, so as to optimize the directivity and isolation of the coupler under the requirement of miniaturized area. It should be noted that the ground (GND) of the first metal layer on the substrate and the ground (GND) of the second metal layer can be a whole area of ground (GND) covered on the first metal layer or the second metal layer of the substrate, or can be a partial area of ground (GND) on the first metal layer or the second metal layer of the substrate, or can also be an area directly connected to the ground (GND) on the first metal layer or the second metal layer of the substrate.

[0052] In a specific embodiment, the at least one capacitance branch includes a first capacitance branch and a second capacitance branch, and the capacitance value of the first capacitance branch is less than that of the second capacitance branch;

[0053] If the coupler operates in the first frequency band, the first resistance branch is turned on, and the first capacitance branch and the second capacitance branch are both turned off;

[0054] If the coupler operates in the second frequency band, the first resistance branch and the first capacitance branch are turned on, and the second capacitance branch is turned off;

[0055] If the coupler operates in the third frequency band, the first resistance branch and the second capacitance branch are turned on, and the first capacitance branch is turned off;

[0056] If the coupler operates in the fourth frequency band, the first resistance branch, the first capacitance branch and the second capacitance branch are all turned on.

[0057] Among them, the first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the third frequency band is greater than the fourth frequency band.

[0058] In at least one embodiment, the higher the operating frequency band of the coupler, the smaller the capacitance value that the switchable circuit needs to present; the lower the operating frequency band of the coupler, the larger the capacitance value that the switchable circuit needs to present. In this embodiment, an example is given with two capacitance branches (the first capacitance branch and the second capacitance branch) and one resistance branch (the first resistance branch), but it is not limited to only including the first capacitance branch and the second capacitance branch, and can also include multiple capacitance branches such as the third capacitance branch and the fourth capacitance branch.

[0059] Exemplarily, in the first frequency band: only the first resistor branch is conducting, and the first capacitor branch and the second capacitor branch are both disconnected. At this time, the capacitance value presented by the switchable circuit is the first capacitance value. In the second frequency band, the first resistor branch and the first capacitor branch are conducting, and the second capacitor branch is disconnected. At this time, the capacitance value presented by the switchable circuit is the second capacitance value; the first resistor branch and the second capacitor branch are conducting, and the first capacitor branch is disconnected. At this time, the capacitance value presented by the switchable circuit is the third capacitance value; in the fourth frequency band, the first resistor branch, the first capacitor branch, and the second capacitor branch are all conducting. At this time, the capacitance value presented by the switchable circuit is the fourth capacitance value. The capacitance value that the switchable circuit needs to present is negatively correlated with the operating frequency band of the coupler. Therefore, when the first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the third frequency band is greater than the fourth frequency band, the first capacitance value is less than the second capacitance value, the second capacitance value is less than the third capacitance value, and the third capacitance value is less than the fourth capacitance value.

[0060] As Figure 3 shown, the coupler includes three branches, a first branch A, a second branch B, and a third branch C. In the first branch A, a capacitor C11 and a switch S1 are connected in series. In the second branch B, a resistor R1 and a switch S2 are connected in series. In the third branch, a capacitor C22 and a switch S3 are connected in series. In this embodiment, the purpose of connecting multiple capacitors in parallel is to change the capacitance value presented by the switchable circuit at different operating frequency bands. The total capacitance value after multiple capacitors are connected in parallel is: C = C1 + C2 + C3 + … + Cn. It can be seen that during the process of continuously connecting capacitors in parallel, the total capacitance value in the circuit will become larger and larger, so as to adapt to lower operating frequencies.

[0061] In this embodiment, the coupler includes a resistor branch and multiple capacitor branches connected in parallel. By changing the states of the multiple capacitor branches, the capacitance value of the capacitor connected to the isolation port of the coupler can be changed to adapt to different capacitance values required by the coupler at different operating frequency bands. And because the resistor branch and the multiple capacitor branches in this embodiment are connected in parallel, the combination of the parallel capacitor branches can not only meet the performance requirements of the coupler for a large capacitance at low frequency bands, but also solve the large capacitance requirements of the coupler in a small chip area, thereby saving design area and cost.

[0062] In a specific embodiment, if the operating frequency band of the coupler is in the range of [1.42 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 2.5 pF].

[0063] In at least one embodiment, the larger the operating frequency band of the coupler, the smaller the capacitance requirement, and the smaller the operating frequency band of the coupler, the larger the capacitance requirement. Therefore, when the coupler operates at a higher frequency band, the capacitance value presented by the switchable branch is smaller, and when the coupler operates at a lower frequency band, the capacitance value presented by the switchable branch is larger. In this embodiment, the operating frequency band of the coupler is in

[0064] [1.42 GHz, 2.69 GHz], and the capacitance value range presented by the switchable branch is [0 pF, 2.5 pF], so as to improve the directivity and isolation of the coupler in a wide frequency band (especially in two frequency points with a large span, such as in the frequency band range of [1.42 GHz, 2.69 GHz]).

[0065] In a specific embodiment, if the operating frequency band range of the coupler is [1.42 GHz, 1.5 GHz], the capacitance value range presented by the switchable branch is [1.2 pF, 2.5 pF]; if the operating frequency band range of the coupler is [1.71 GHz, 2.1 GHz], the capacitance value range presented by the switchable branch is [0.5 pF, 1.2 pF]; if the operating frequency band range of the coupler is [2.3 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 0.5 pF].

[0066] In at least one embodiment, the larger the operating frequency band of the coupler, the smaller the capacitance requirement, and the smaller the operating frequency band of the coupler, the larger the capacitance requirement. Therefore, when the coupler operates at a higher frequency band, the capacitance value presented by the switchable branch is smaller, and when the coupler operates at a lower frequency band, the capacitance value presented by the switchable branch is larger. In this embodiment, if the operating frequency band of the coupler is in

[0067] [1.42 GHz, 1.5 GHz] range, the capacitance value range presented by the switchable branch is [1.2 pF, 2.5 pF]; if the operating frequency band of the coupler is in [1.71 GHz, 2.1 GHz] range, the capacitance value range presented by the switchable branch is [0.5 pF, 1.2 pF]; if the operating frequency band of the coupler is in [2.3 GHz, 2.69 GHz] range, the capacitance value range presented by the switchable branch is [0 pF, 0.5 pF]; so as to improve the directivity and isolation of the coupler in different frequency bands of a wide frequency band (especially in two frequency points with a large span, such as in the frequency band range of [1.42 GHz - 2.69 GHz]).

[0068] In a specific embodiment, the coupler further includes a third compensation capacitor. After the first capacitor branch and the first resistor branch are connected in parallel, they are connected to the first end of the third compensation capacitor, and the second end of the third compensation capacitor is grounded. As Figures 1 to 7 shown, the first branch A, the second branch B, and the third branch C are connected in parallel and then connected to one end of the third compensation capacitor C20, and the other end of the third compensation capacitor C20 is grounded.

[0069] In at least one embodiment, when the nodes where each capacitor branch and resistor branch are connected are connected to the ground, a third compensation capacitor C20 can be further connected. The third compensation capacitor C20 can be an equivalent capacitor formed by the ground (GND) of the first metal layer on the substrate directly below the chip and the metal on the chip, or an equivalent capacitor formed by the ground (GND) of the first metal layer on the substrate and the ground (GND) of the second metal layer. Thus, under the requirement of miniaturized area, the directivity and isolation of the coupler can be optimized. It should be noted that the ground (GND) of the first metal layer on the substrate and the ground (GND) of the second metal layer can be a whole area of ground (GND) covered on the first metal layer or the second metal layer of the substrate, or a partial area of ground (GND) on the first metal layer or the second metal layer of the substrate, or an area directly connected to the ground (GND) on the first metal layer or the second metal layer of the substrate.

[0070] In a specific embodiment, the resistor branch further includes a switch S1 connected in series with the first resistor.

[0071] In at least one embodiment, the first resistor branch includes a resistor R1 and a switch S1 connected in parallel. The Ron of the switch S1 in the conducting state can be utilized to more flexibly adjust the resistance value presented by the switchable circuit.

[0072] In at least one embodiment, the more parallel capacitor branches are connected to the coupler, the larger the total capacitance value in the circuit will be, which can adapt to the coupler working in a lower frequency band and meet the requirement of high isolation within the working range of the lower frequency band. Isolation is a measure to suppress interference taken to minimize the influence of various interferences on the receiver. The more parallel capacitor branches are connected in parallel, the stronger the anti-interference ability of the coupler and the better the performance. However, the area and manufacturing cost of the chip will also increase accordingly.

[0073] It can be seen that in this embodiment, multiple parallel capacitor branches are used to broaden the operating frequency band of the coupler. The more capacitors are connected in parallel, the lower the frequency circuit the coupler can operate in. If the coupler operates in a higher frequency circuit, the switch can also be disconnected to reduce the number of capacitors combined in the circuit, thereby reducing the equivalent capacitance value in the circuit and meeting the small capacitance requirement in the high frequency band. Preferably, to avoid excessive occupied area of the coupler, the coupler in this embodiment includes two capacitor branches (the first capacitor branch and the second capacitor branch) and one resistor branch (the first resistor branch).

[0074] Embodiment 2

[0075] A radio frequency front-end module includes a substrate, a first chip disposed on the substrate, and a coupler disposed on the first chip. The coupler includes: an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, the first end of the switchable branch is connected to the isolation port, the second end is grounded, and the switchable branch includes a resistor branch and at least one group of capacitor branches connected in parallel. The resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch.

[0076] Optionally, the first chip can be disposed on the substrate in a flip-chip manner or in a wire bonding manner. This embodiment does not specifically limit the connection manner between the first chip and the substrate.

[0077] In at least one embodiment, the first chip can be manufactured based on the GaAs (gallium arsenide) process or can be manufactured based on the CMOS (complementary metal oxide semiconductor) process, etc. This embodiment does not specifically limit the process manufacturing method of the first chip.

[0078] In a specific embodiment, as Figures 1 to 7 shown, the first chip includes a first metal layer, the coupling line 30 includes a first coupling coil segment 31, the first coupling coil segment 31 and the main line 10 are disposed opposite to each other, the first coupling coil segment 31 is wound to form a first region, and the switchable branch is located in the first region. Among them, the first region formed by winding the first coupling coil segment 31 can be a region of any shape such as a circle, a quadrilateral or a polygon. The first region can be a closed region or an open region. For example: as Figure 6 and Figure 7 shown, the first region formed by winding the first coupling coil segment 31 is a closed quadrilateral region.

[0079] In at least one embodiment, by disposing the switchable branch in the first region formed by winding the first coupling coil segment 31, not only can the performance requirement of a large capacitance of the coupler in the low-frequency band be achieved, but also the requirement of a large capacitance under a small chip area can be solved, thereby saving the design area and cost.

[0080] In a specific embodiment, at least one group of capacitance branches and resistance branches are arranged in sequence in the first region in a direction away from the main line, and the resistance branch is disposed in the central region of the first region.

[0081] In at least one embodiment, the number of capacitance branches can be any number such as one, two, or three, etc. There is one resistance branch. This embodiment takes the case of including two capacitance branches (the first capacitance branch and the second capacitance branch) as an example for illustrative description.

[0082] As an example, the first capacitance branch, the resistance branch, and the second capacitance branch are arranged in sequence in the first region in a direction away from the main line, and the resistance branch is disposed in the central region of the first region, that is, between the first capacitance branch and the second capacitance branch; thereby, the directivity of the isolation end of the coupler within a wide frequency band range can be ensured.

[0083] In a specific embodiment, if the capacitance value of the capacitor in the first capacitance branch is greater than the capacitance value of the capacitor in the second capacitance branch, then the first capacitance branch with a larger capacitance value is disposed in the region close to the main line of the coupler (the left region of the resistance branch in the figure), and the second capacitance branch with a smaller capacitance value is disposed in the region away from the main line of the coupler (the right region of the resistance branch in the figure); thereby, the reasonable layout of the switchable circuit in the first region can be further optimized, and the area can be saved.

[0084] In a specific embodiment, the first chip further includes a first metal layer and a second metal layer disposed adjacent to each other. The first coupling coil segment and the main line are located in the first metal layer. The first coupling line portion 20 is disposed in the second metal layer. The first coupling line portion 20 is connected to the first coupling coil segment 31 through a via hole. The first coupling line portion 20 and the main line 10 overlap at least partially in the longitudinal direction. Among them, the first coupling line portion 20 can be connected to the first coupling coil segment 31 through a metal via hole.

[0085] In at least one embodiment, the first coupling line portion and the main line overlap at least partially in the longitudinal direction to form a compensation capacitance.

[0086] As an example, the first coupling line portion 20 disposed on the second metal layer and the first coupling coil segment 31 disposed on the first metal layer can be connected through a metal via or a jumper. It can be understood that the first coupling coil segment 31 disposed on the first metal layer and the main line 10 are spaced apart and coupled to each other, and at least a part of the projection of the first coupling line portion and the main line in the longitudinal direction overlaps.

[0087] In this embodiment, by making at least a part of the projection of the first coupling line portion and the main line in the longitudinal direction overlap, a compensation capacitor is formed. By setting the overlapping area between the first coupling line portion and the main line or the coupling distance between the first coupling line portion and the main line, the capacitance value of the formed compensation capacitor can be changed. Since the capacitance value of the compensation capacitor is related to the isolation of the coupler, therefore, by making at least a part of the projection of the first coupling line portion and the main line in the longitudinal direction overlap, the capacitance value of the formed compensation capacitor can be flexibly adjusted, thereby improving the directivity and isolation of the coupler in a wide frequency band (especially at two frequency points with a large span, such as:

[0088] [1.42 GHz, 2.69 GHz] frequency band range to meet the actual requirements.

[0089] In a specific embodiment, the resistor and the switch in at least one group of the capacitor branches can be components formed by connecting multiple transistors (such as MOS transistors) in series, and each transistor is implemented as a finger-comb configuration device. The active transistor of the switch in this embodiment is the transistor that makes up the switch; for example: MOS transistor, and the MOS transistor can be a PMOS transistor or an NMOS transistor.

[0090] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A coupler, characterized in that, it includes an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, a first end of the switchable branch is connected to the isolation port, a second end is grounded, the switchable branch includes a resistor branch and at least one group of capacitor branches connected in parallel, the resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch.

2. The coupler according to claim 1, characterized in that, the first resistor branch further includes a first compensation capacitor, the first compensation capacitor is connected in parallel with the resistor of the first resistor branch, and / or, the capacitor branch further includes a second compensation capacitor, the second compensation capacitor is connected in parallel with the capacitor of the capacitor branch.

3. The coupler according to claim 1, characterized in that, the at least one capacitor branch includes a first capacitor branch and a second capacitor branch, and the capacitance value of the first capacitor branch is less than the capacitance value of the second capacitor branch; if the coupler operates in a first frequency band, the first resistor branch is turned on, and the first capacitor branch and the second capacitor branch are both turned off; if the coupler operates in a second frequency band, the first resistor branch and the first capacitor branch are turned on, and the second capacitor branch is turned off; if the coupler operates in a third frequency band, the first resistor branch and the second capacitor branch are turned on, and the first capacitor branch is turned off; if the coupler operates in a fourth frequency band, the first resistor branch, the first capacitor branch and the second capacitor branch are all turned on; wherein, the first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the third frequency band is greater than the fourth frequency band.

4. The coupler according to claim 3, characterized in that, if the operating frequency band of the coupler is in the range of [1.42 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 2.5 pF].

5. The coupler according to claim 4, characterized in that, if the operating frequency band of the coupler is in the range of [1.42 GHz, 1.5 GHz], the capacitance value range presented by the switchable branch is [1.2 pF, 2.5 pF]; if the operating frequency band of the coupler is in the range of [1.71 GHz, 2.1 GHz], the capacitance value range presented by the switchable branch is [0.5 pF, 1.2 pF]; if the operating frequency band of the coupler is in the range of [2.3 GHz, 2.69 GHz], the capacitance value range presented by the switchable branch is [0 pF, 0.5 pF].

6. The coupler according to claim 1, characterized in that, the coupler further includes a third compensation capacitor, the capacitor branch and the first resistor branch are connected in parallel and then connected to the first end of the third compensation capacitor, and the second end of the third compensation capacitor is grounded.

7. The coupler according to claim 6, It is characterized in that the capacitance value range of the third compensation capacitor is [0.1 pF, 1 pF].

8. The coupler according to claim 1, It is characterized in that the resistor branch further includes a switch connected in series with the first resistor.

9. A radio frequency front-end module, characterized in that it includes a substrate, a first chip disposed on the substrate, and a coupler disposed on the first chip, the coupler comprises: an input port; an output port; a coupling port; an isolation port; a main line, one end of the main line is connected to the input port, and the other end is connected to the output port; a coupling line, one end of the coupling line is connected to the coupling port, and the other end is connected to the isolation port; a switchable branch, the first end of the switchable branch is connected to the isolation port, the second end is grounded, the switchable branch includes a resistor branch and at least one group of capacitor branches connected in parallel, the resistor branch includes a first resistor, and each capacitor branch includes a capacitor and a switch.

10. The radio frequency front-end module according to claim 9, It is characterized in that the first chip includes a first metal layer, the coupling line includes a first coupling coil segment, the first coupling coil segment and the main line are oppositely arranged, the first coupling coil segment is wound to form a first region, wherein the switchable branch is located in the first region.

11. The radio frequency front-end module according to claim 10, It is characterized in that at least one group of the capacitor branches and the resistor branch are arranged in sequence in the first region in a direction away from the main line, and the resistor branch is arranged in the central region of the first region.

12. The radio frequency front-end module according to claim 10, It is characterized in that the first capacitor branch, the resistor branch and the second capacitor branch are arranged in sequence in a direction away from the main line.

13. The radio frequency front-end module according to claim 9, It is characterized in that the first chip further includes a first metal layer and a second metal layer arranged adjacent to each other, the first coupling coil segment and the main line are located in the first metal layer, the coupling line further includes a first coupling line portion, the first coupling line portion is disposed in the second metal layer, the first coupling line portion is connected to the first coupling coil segment through a via hole, and the first coupling line portion and the main line overlap at least partially in the longitudinal direction.

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