A wideband matching circuit, a signal processing circuit, and a wideband post matching circuit

Abstract

The application provides a broadband matching circuit, a signal processing circuit and a broadband post-matching circuit. The broadband matching circuit comprises an input end, an output end, one or more connecting line circuits and one or more branch circuits. One or more connecting line circuits are connected in series between the input end and the output end, and the branch circuits are connected in parallel to one end of the connecting line circuits. Any connecting line circuit adopts a ladder structure, any branch circuit adopts a ladder structure, and the ladder structure comprises two transmission lines.

Description

Technical Field

[0001] This application relates to the field of communication technology, specifically to a broadband matching circuit, a signal processing circuit, and a broadband post-matching circuit. Background Technology

[0002] Current research on high-efficiency operating modes of power amplifier transistors is based on waveform shaping theory, with typical examples including Class E, Class F / inverse Class F, continuous Class F / inverse Class F, and Class J. Theoretically, by precisely controlling the harmonic impedance, the overlap between the time-domain current and voltage waveforms can be reduced, thereby achieving the goals of reducing heat dissipation and improving efficiency. Although the theoretical derivations for each mode differ slightly, the implementation methods of these high-efficiency modes are all similar, requiring the broadband matching circuits to simultaneously achieve precise matching of the fundamental frequency impedance and precise control of the harmonic impedance.

[0003] Existing broadband matching circuits typically consist of two parts: a separately designed harmonic control circuit and a fundamental frequency matching circuit. Usually, in order to achieve an ideal open or short circuit for the harmonic impedance, the harmonic control circuit consists of multiple connecting lines and stubs of specified electrical lengths. These specified electrical lengths refer to λ / 8 or λ / 16 at the fundamental frequency. The fundamental frequency impedance matching problem is then handled separately by the fundamental frequency matching circuit.

[0004] Existing broadband matching circuits are typically complex and their broadband characteristics are difficult to guarantee. Summary of the Invention

[0005] This application provides a broadband matching circuit, a signal processing circuit, and a broadband post-matching circuit, which can simultaneously achieve precise matching of fundamental frequency impedance and precise control of harmonic impedance in a single broadband matching circuit.

[0006] In a first aspect, embodiments of this application provide a broadband matching circuit, comprising: an input terminal, an output terminal, one or more connecting line circuits, and one or more stub circuits; wherein...

[0007] One or more of the connecting line circuits are connected in series between the input terminal and the output terminal, and the stub circuit is connected in parallel to one end of the connecting line circuit;

[0008] Any of the aforementioned connecting line circuits adopts a stepped structure, and any of the aforementioned branch circuits adopts a stepped structure, wherein the stepped structure comprises two transmission lines.

[0009] Secondly, embodiments of this application provide a signal processing circuit, which includes: a stabilization circuit, a bias circuit, a DC blocking circuit, and any of the broadband matching circuits provided in embodiments of this application.

[0010] Thirdly, embodiments of this application provide a broadband post-matching circuit, which is applied to a Doherty power amplifier circuit, and the broadband post-matching circuit includes any of the broadband matching circuits provided in embodiments of this application.

[0011] Based on the fundamental frequency broadband matching circuit, this application achieves precise matching of fundamental frequency impedance and precise control of harmonic impedance in a single broadband matching circuit without the need for a separate harmonic control network. This ensures both a compact circuit layout and a broadband frequency response characteristic.

[0012] Further details regarding the above embodiments and other aspects of this application, as well as their implementations, are provided in the accompanying drawings, detailed description, and claims. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the broadband matching circuit provided in this application;

[0014] Figure 2 This is a schematic diagram of the broadband matching circuit with a third-order bandpass structure provided in this application;

[0015] Figure 3 This is a schematic diagram of the broadband matching circuit with a fourth-order bandpass structure provided in this application;

[0016] Figure 4 This is a schematic diagram of the simulation results of the broadband matching circuit with a fourth-order bandpass structure provided in this application;

[0017] Figure 5 This is a schematic diagram of the broadband matching circuit provided in this application involving a symmetrical structure.

[0018] Figure 6 This is a connection diagram of the signal processing circuit provided in this application;

[0019] Figure 7 This is a connection diagram of the post-matching circuit used in the Doherty power amplifier provided in this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0021] The steps illustrated in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases the steps shown or described may be performed in a different order than that presented here.

[0022] As the unit with the largest power consumption in a wireless communication system, the efficiency of a power amplifier directly affects the overall energy consumption of the system. In traditional high-efficiency modes, efficiency improvement is achieved by adjusting the gate bias voltage of the transistor to control the transistor's conduction angle, such as Class A, Class B, Class AB, and Class C modes. Since it is impossible to reduce the conduction angle indefinitely, this simple control mode cannot achieve sustainable efficiency improvement, and continuously reducing the conduction angle will bring many problems, such as reduced usable gain, decreased saturation power, and deteriorated linearity.

[0023] Current research on high-efficiency operating modes of power amplifier transistors is based on waveform shaping theory, with typical examples including Class E, Class F / inverse Class F, continuous Class F / inverse Class F, and Class J. Theoretically, by precisely controlling the harmonic impedance, the overlap between the time-domain current and voltage waveforms can be reduced, thereby achieving the goals of reducing heat dissipation and improving efficiency. Although the theoretical derivations for each mode differ slightly, the implementation methods of these high-efficiency modes are all similar, requiring the broadband matching circuits to simultaneously achieve precise matching of the fundamental frequency impedance and precise control of the harmonic impedance.

[0024] Existing broadband matching circuits typically consist of two parts: a separately designed harmonic control circuit and a fundamental frequency matching circuit. The circuit structure is usually complex, and broadband characteristics are difficult to guarantee. Typically, to achieve ideal open or short circuit harmonic impedance, the harmonic control circuit consists of multiple connecting lines and stubs of specified electrical lengths. These specified electrical lengths refer to λ / 8 or λ / 16 at the fundamental frequency. The fundamental frequency impedance matching problem is then handled separately by the fundamental frequency matching circuit.

[0025] Furthermore, the biggest drawback of the above scheme is that it approximates the internal equivalent current source reference plane as the external package reference plane, ignoring the influence of various parasitic parameters between the two reference planes. In practice, parasitic parameters will cause the open circuit or short circuit of the package reference plane to be not equivalent to the open circuit or short circuit of the internal equivalent current source reference plane. Therefore, the harmonic impedance handling in the above scheme cannot achieve the intended waveform shaping purpose.

[0026] This application provides a fundamental frequency broadband matching and harmonic control circuit for use in broadband power amplifiers. Based on achieving precise fundamental frequency impedance matching, it simultaneously achieves precise fundamental frequency impedance matching and precise harmonic impedance control in a single circuit unit.

[0027] This application provides a structural diagram of a broadband matching circuit. Figure 1 This is a structural diagram of the broadband matching circuit provided in this application, which simultaneously achieves precise matching of fundamental frequency impedance and precise control of harmonic impedance.

[0028] like Figure 1As shown, the broadband matching circuit provided in this application embodiment includes: an input terminal IN, an output terminal OUT, one or more connecting line circuits 11, and one or more stub circuits 12; wherein,

[0029] One or more of the connecting line circuits 11 are connected in series between the input terminal IN and the output terminal OUT, and the spur circuit 12 is connected in parallel to one end of the connecting line circuit 11; any of the connecting line circuits 11 adopts a stepped structure, and any of the spur circuits 12 adopts a stepped structure, wherein the stepped structure includes two transmission lines.

[0030] The stepped structure comprises two transmission lines of equal electrical length but unequal impedance. Specifically, the connecting line circuit includes two transmission lines of equal electrical length but unequal impedance, and the spur circuit includes two transmission lines of equal electrical length but unequal impedance.

[0031] Both the connecting line circuit and the stub circuit adopt a stepped structure, but the parameters of the two transmission line segments in the connecting line circuit are different from those in the stub circuit. The parameters of the two transmission line segments in each connecting line circuit are different, and the parameters of the two transmission line segments in each stub circuit are also different. These parameters include the electrical length and impedance of the transmission lines.

[0032] Furthermore, the broadband matching circuit includes: N connecting line circuits 11 and M stub circuits 12, wherein the m-th stub circuit is connected in parallel to one end of the n-th connecting line circuit.

[0033] In this embodiment, M and N are any integers greater than or equal to 1. m is any integer from 1 to M, and n is any integer from 1 to N.

[0034] Preferably, M can be equal to N, less than N, or greater than N. The number of branch circuits M can be flexibly adjusted based on rationality and simulation results.

[0035] It should be noted that while larger values ​​of N and M increase circuit complexity, the harmonic suppression effect does not increase proportionally with the increase of N and M. That is, as N and M increase, the improvement in harmonic suppression effect is not significant, but the circuit complexity increases significantly. Therefore, to balance harmonic suppression effect and circuit complexity, N is preferably 1, or preferably 2.

[0036] In one exemplary embodiment, the two transmission lines in the stepped structure have equal electrical lengths but unequal impedances.

[0037] In one exemplary embodiment, the impedances of the two transmission lines in the connection circuit are determined by the circuit parameters of a predetermined baseband broadband matching circuit.

[0038] In one exemplary embodiment, the electrical length of the transmission line in the connection circuit is determined by the impedance of each segment of the transmission line in the connection circuit and a first preset formula.

[0039] Furthermore, the electrical length of each transmission line segment in the stub circuit is one-quarter wavelength.

[0040] In one exemplary embodiment, the impedance value Z of the first transmission line in the spur circuit is... IN It is determined by the predetermined circuit parameters Z of the baseband broadband matching circuit, the first set angle, the first parameter, and the second preset formula.

[0041] In one exemplary embodiment, the first set angle is determined by the ratio of the passband edge angular frequency of the baseband broadband matching circuit to the angular frequency of the center frequency.

[0042] In one exemplary embodiment, the first parameter is determined by the ratio of the angular frequency corresponding to the sideband transmission zero of the baseband broadband matching circuit to the angular frequency of the center frequency.

[0043] In one exemplary embodiment, the impedance value Z of the second transmission line in the spur circuit is... OUT It is determined by the product of the impedance of the first transmission line segment and the first parameter.

[0044] In one application embodiment, a broadband matching circuit for a broadband power amplifier is provided. The broadband matching circuit consists of a series connecting line circuit and a parallel stub circuit. The broadband matching circuit proposed in this application eliminates the need for independent design of fundamental frequency matching and harmonic modulation networks. It can simultaneously achieve precise matching of the preferred fundamental impedance and precise modulation of the preferred harmonic impedance within a single circuit unit, resulting in a more compact circuit structure. Because this circuit is based on a broadband matching structure, it effectively guarantees the broadband response of the circuit.

[0045] Figure 2 This is a schematic diagram of the broadband matching circuit with a third-order bandpass structure provided in this application, corresponding to the case of N=1 and M=2, as shown below. Figure 2 As shown, the fundamental frequency broadband matching circuit consists of a series connecting line M1 and parallel branches M2 and M3. The harmonic modulation proposed in this application is obtained by transforming the aforementioned fundamental frequency broadband matching circuit. The connection method is as follows: the branch circuit composed of transmission line K3 and the terminal open-circuit transmission line K4 is connected to the left end of transmission line K1 in the connecting line circuit. Similarly, the branch circuit composed of transmission line K5 and the terminal open-circuit transmission line K6 is connected to the right end of transmission line K2 in the connecting line circuit.

[0046] It should be noted that the circuit connection method of the fourth-order bandpass structure is similar to that of the third-order bandpass structure, and will not be repeated here.

[0047] In one application implementation, a broadband matching circuit is provided, which utilizes a stepped stub circuit and a stepped connecting line circuit to achieve fundamental frequency impedance matching and harmonic impedance modulation. With acceptable complexity, the fourth-order circuit provides more flexible impedance matching and modulation capabilities. Therefore, this embodiment mainly describes a fourth-order bandpass structure, corresponding to the case of N=2.

[0048] Furthermore, it should be noted that the input and output matching circuits can use the same structure; therefore, in this embodiment, only the output matching circuit will be used as an example for explanation.

[0049] Figure 3 This is a schematic diagram of the broadband matching circuit with a fourth-order bandpass structure provided in this application, corresponding to the case of N=2 and M=3, as shown below. Figure 3 As shown, the baseband broadband matching circuit consists of series connecting lines N1 and N2, and parallel branches N3, N4, and N5. The broadband matching circuit proposed in this application is a modification of the aforementioned baseband broadband matching circuit. It should be noted that the embodiment of this application uses N=2 as an example, but the circuit scheme with N=1 is also within the scope of protection.

[0050] The implementation of the technical solution will be further described in detail below with reference to the accompanying drawings. The main design steps of the broadband matching circuit are as follows:

[0051] Step 1: Based on the load pull, obtain the optimal impedance information for the entire frequency band. According to the analytical formula or the executable instructions in the computer, obtain the specific circuit parameters of the fundamental frequency broadband matching circuit. The characteristic impedances of the two connecting lines N1 and N2 are 13Ω and 29Ω, respectively, and the electrical length is a quarter wavelength. The characteristic impedances of the branch connecting lines N3, N4, and N5 are 6.81Ω, 20.7Ω, and -116Ω, respectively, and the electrical length is a quarter wavelength. The terminal short circuit is also a short circuit.

[0052] Specifically, the optimal impedance information is extracted based on the nonlinear simulation model provided by the manufacturer. The die model used in this embodiment is CG2H40025.

[0053] It should be noted that in this embodiment, the calculated impedance value of spur N5 is negative, which is equivalent to spur N5 having infinite impedance in practice. Furthermore, considering the limitations of actual board fabrication, spur N5 can be omitted in this embodiment. However, it should be understood that spur N5 having infinite impedance is only one special case and does not limit the impedance of the spur connection line N5.

[0054] Step 2: Based on the aforementioned fundamental frequency broadband matching circuit, replace the two series connection lines N1 and N2. The goal of this circuit replacement is to complete the regulation of harmonic impedance in the first stage.

[0055] Specifically, replace connecting line N1 with a connecting line circuit consisting of transmission lines T1 and T2 connected in series; replace connecting line N2 with a connecting line circuit consisting of connecting transmission lines T3 and T4 connected in series.

[0056] Transmission lines T1 and T2 are two transmission lines with equal electrical lengths but unequal impedances; transmission lines T3 and T4 are two transmission lines with equal electrical lengths but unequal impedances.

[0057] The impedance of the transmission line in the connecting line circuit can be determined by the impedance parameters of the fundamental frequency broadband matching circuit. The electrical length of the transmission line in the connecting line circuit can be determined by the impedance of the two segments of the transmission line in the connecting line circuit.

[0058] Specifically, the electrical lengths of transmission lines T1 and T2 can be determined by the impedances of transmission lines T1 and T2, respectively. Similarly, the impedances and electrical lengths of transmission lines T3 and T4 can be determined sequentially using the same method, without further explanation.

[0059] Specifically, the electrical length of the transmission line is obtained by calculating according to the first preset formula, namely formula (1).

[0060]

[0061] Where Z2 represents the high impedance in the connecting line circuit, Z1 represents the low impedance in the connecting line circuit, and α represents the electrical length of the replaced transmission line.

[0062] Step 3: Replace the stepped structure branch circuit.

[0063] Based on the simulation results of step two, transmission zeros are introduced purposefully at different harmonic frequencies to realize the impedance control strategy in the second stage.

[0064] Branch N3 is replaced by a branch circuit consisting of transmission line T5 and terminal open line T6 connected in series; branch N4 is replaced by a branch circuit consisting of transmission line T7 and terminal open line T8 connected in series; and branch N5 is replaced by a branch circuit consisting of transmission line T9 and terminal open line T10 connected in series.

[0065] As mentioned earlier, the theoretical calculated value of spur N5 is negative. In this embodiment, spur N5 can be omitted, and the circuit no longer involves connecting lines T9 and T10.

[0066] Among them, transmission line T5 and terminal open line T6 are two transmission lines with equal electrical length but unequal impedance; transmission line T7 and terminal open line T8 are two transmission lines with equal electrical length but unequal impedance.

[0067] In this embodiment, the electrical lengths of transmission line T5, terminal open line T6, transmission line T7, and terminal open line T8 are theoretically all quarter wavelengths.

[0068] Equivalent transformations are performed according to formulas (2) to (4), replacing the branch connection lines with the corresponding stepped branch circuits.

[0069]

[0070]

[0071]

[0072] Where ω1 is the normalized passband edge angular frequency, ω0 is the angular frequency of the center frequency, and ω ∞ Z is the angular frequency corresponding to the proposed sideband transmission zero, where Z IN Z is the impedance value of the first transmission line segment in the spur circuit. OUT Z is the impedance of the second transmission line in the stub circuit, and Z is the impedance value of the stub transmission line in the fundamental frequency broadband matching circuit.

[0073] Based on the above formula, the impedance values ​​of each connecting line in each support unit are calculated sequentially.

[0074] Step 4: Optimize circuit parameters.

[0075] It should be noted that the impedance and electrical length obtained in steps two and three are theoretical calculations. Due to parasitic effects such as discontinuities in the connecting lines, circuit optimization is required in actual engineering. The matching circuit is connected to the bias circuit, stabilizing circuit, and DC blocking circuit, and the overall layout is optimized to obtain the final circuit dimensions.

[0076] The final circuit parameters of this embodiment are briefly described as follows: T1: 14.9Ω 28.6°@2.2GHz; T2: 11.4Ω 35.2°@2.2GHz; T3: 44.9Ω 25.4°@2.2GHz; T4: 16Ω 23.8°@2.2GHz; T5: 24.9Ω 114.2°@2.2GHz; T6: 12.9Ω 69.1°@2.2GHz; T7: 50Ω 121.6°@2.2GHz; T8: 23.1Ω 39.6°@2.2GHz.

[0077] It should be noted that the final circuit parameters may differ from the theoretically calculated values, but such differences cannot be considered as exceeding the scope of protection of this application.

[0078] Figure 4 This is a schematic diagram of the simulation results of the broadband matching circuit with a fourth-order bandpass structure provided in this application, as shown below. Figure 4 As shown, the transmission characteristics remain unchanged in the fundamental frequency band (1.7 GHz - 2.7 GHz), and significant sideband suppression effects are observed in the second and third harmonic frequency bands, thus realizing the function of harmonic modulation.

[0079] In one application example, the theoretical impedance value of the spur circuit might be negative, indicating the need for an infinite characteristic impedance. However, the maximum impedance achievable by a PCB is generally no more than 120 ohms, making an infinite characteristic impedance impossible. In practice, this spur circuit can be omitted. In this embodiment, the theoretically calculated value of spur circuit N5 is negative, thus, as a special case, spur circuit N5 is not introduced. The number of connecting lines and the number of spurs in this broadband matching circuit are equal, i.e., M equals N.

[0080] In another application example, if the theoretical calculation yields a small stub impedance, leading to an excessively wide transmission line width in the layout implementation, a symmetrical stub design can be used to mitigate the negative impact of unreasonable physical dimensions of the transmission line. Figure 5 This is a schematic diagram of the spur-symmetric broadband matching circuit provided in this application, as shown below. Figure 5 As shown, assuming that for the case of N=1 and M=2, the first stub exhibits excessively low impedance, a more reasonable stub impedance value can be obtained by using two parallel stub circuits (a stub circuit consisting of K3' and K4' connected in series), which facilitates layout implementation. Furthermore, as... Figure 5 As shown, one branch circuit is above the connecting line circuit, and the other branch circuit is below the connecting line circuit.

[0081] In one exemplary embodiment, this application provides a signal processing circuit, including: a stabilization circuit, a bias circuit, a DC blocking circuit, and a broadband matching circuit as described in any of the embodiments of this application.

[0082] Figure 6 This is a connection diagram of the signal processing circuit provided in this application. See [link / reference]. Figure 6The diagram shows the connection of the signal processing circuit, including a power amplifier chip, a stabilizing circuit, a gate bias circuit, a wideband input / output matching circuit, a drain bias circuit, a DC blocking circuit, and input / output port lines (50Ω). The DC blocking circuit is connected to a standard termination impedance of 50Ω. The stabilizing circuit is connected to the input terminal of the chip. The wideband input matching circuit is connected to the input terminal of the chip and is also connected to the stabilizing circuit, the gate bias circuit, and the DC blocking circuit. The wideband output matching circuit is connected to the output terminal of the chip and is also connected to the drain bias circuit and the DC blocking circuit, thus simultaneously achieving the circuit functions of harmonic regulation and fundamental frequency matching.

[0083] Among these, the input and output broadband matching circuits are the core circuit design, namely the fundamental frequency matching and harmonic control circuits provided in the above embodiments. Furthermore, it should be understood that the bias circuit and stabilization circuit can be flexibly configured in their connection order with other circuit units according to the specific design. This application only provides an exemplary description of the most commonly used connection order. It is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings for those skilled in the art.

[0084] The connection order of the broadband matching circuit, stabilization circuit, bias circuit, and DC blocking circuit can be changed. For example, the position of the input stabilization circuit can be before or after the input matching circuit.

[0085] Stabilizing circuits are typically only installed at the input terminal.

[0086] The bias circuit can be placed in many locations, such as near the power amplifier pins, near the DC blocking circuit, or directly connected to the matching circuit. Therefore, the possible connection order of the bias circuit is very diverse, and will not be listed one by one in this embodiment.

[0087] It should be understood that changing the connection relationship between the stabilizing circuit, the bias circuit, the DC blocking circuit and the broadband matching circuit is still within the scope of protection of this application.

[0088] It should be noted that the above embodiments are merely illustrative examples of the circuit connection sequence and are not limited thereto. Other common circuit connection relationships not shown are still within the protection scope of this application.

[0089] It should be noted that the circuit implemented using this technology can be used in the design of input or output circuits for single-transistor power amplifiers, and can further become a component in other power amplifier units, such as the "post-matching" circuit in a wideband Doherty power amplifier. Figure 7 As shown.

[0090] It should be noted that the basic feature of the broadband matching circuit proposed in this application is that the branch section is composed of a stepped structure consisting of two transmission lines with different impedances, and the connecting circuit between the branches is also composed of two transmission lines with different impedances. The calculation formulas provided in this application, including the first preset formula, the second preset formula, the first set angle, and the first parameter, are merely illustrative of the calculation process for the initial values ​​of circuit parameters used for broadband matching with similar structural features. Other theoretical calculation methods are not excluded, but circuit designs that conform to the stepped circuit structure features proposed in this application are still within the protection scope of this application.

[0091] The above description is merely an exemplary embodiment of this application and is not intended to limit the scope of protection of this application.

[0092] The above description of the embodiments is merely for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in this application can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to the embodiments shown in the application, but is to be accorded the widest scope consistent with the principles and novel features disclosed in this application.

[0093] A detailed description of exemplary embodiments of this application has been provided above through exemplary and non-limiting examples. However, various modifications and adjustments to the above embodiments will be apparent to those skilled in the art when considered in conjunction with the accompanying drawings and claims, without departing from the scope of the invention. Therefore, the proper scope of the invention will be determined by the claims.

Claims

1. A broadband matching circuit, characterized in that, include: Input terminal, output terminal, one or more connecting wire circuits, one or more stub circuits; wherein... One or more of the connecting line circuits are connected in series between the input terminal and the output terminal, and the stub circuit is connected in parallel to one end of the connecting line circuit; Any of the aforementioned connecting line circuits adopts a stepped structure, and any of the aforementioned branch circuits adopts a stepped structure, wherein the stepped structure includes two transmission lines; wherein the two transmission lines in the stepped structure have equal electrical lengths but unequal impedances; The impedances of the two transmission lines in the connecting line circuit are determined by the circuit parameters of the predetermined baseband broadband matching circuit, and the electrical length of the transmission lines in the connecting line circuit is determined by the impedance of each transmission line in the connecting line circuit and the first preset formula. The impedance of the first transmission line in the spur circuit is determined by the circuit parameters of the predetermined baseband broadband matching circuit, the first set angle, the first parameter, and the second preset formula.

2. The circuit according to claim 1, characterized in that, The first set angle is determined by the ratio of the passband edge angular frequency to the center frequency of the fundamental frequency broadband matching circuit.

3. The circuit according to claim 1, characterized in that, The first parameter is determined by the ratio of the angular frequency corresponding to the sideband transmission zero of the fundamental frequency broadband matching circuit to the angular frequency of the center frequency.

4. The circuit according to claim 1, characterized in that, The impedance of the second transmission line in the stub circuit is determined by the product of the impedance of the first transmission line and the first parameter.

5. A signal processing circuit, characterized in that, The signal processing circuit includes: a stabilization circuit, a bias circuit, a DC blocking circuit, and a broadband matching circuit as described in any one of claims 1-4.

6. A broadband post-matching circuit, characterized in that, The broadband post-matching circuit is applied to the Doherty power amplifier circuit, and the broadband post-matching circuit includes the broadband matching circuit as described in any one of claims 1-4.

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