Power combining circuit and power amplifier

Abstract

A power combining circuit and a power amplifier. The power combining circuit comprises a first signal input end, a second signal input end, an input impedance matching circuit, a first harmonic suppression circuit, a second harmonic suppression circuit, a first high-pass filter circuit, a second high-pass filter circuit, a low-pass filter circuit, and a signal combining output end; the low-pass filter circuit comprises a first inductor, a second inductor, and a first capacitor; a first end of the first inductor serves as a first input end of the low-pass filter circuit, a first end of the second inductor serves as a second input end of the low-pass filter circuit, a second end of the first inductor is separately connected to a first end of the first capacitor and a second end of the second inductor and serves as an output end of the low-pass filter circuit, and a second end of the first capacitor is grounded. The power combining circuit has impedance transformation characteristics, and also has advantages such as low costs, high isolation, and high integration.

Description

Power combining circuit and power amplifier Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a power combining circuit and a power amplifier. Background Technology

[0002] In wireless communication systems, the rapid development of 5G networks and Internet of Things (IoT) technologies has placed higher demands on the linear power of radio frequency (RF) front-end modules. However, single-ended power amplifiers struggle to output higher power, necessitating the use of power combining techniques. Existing RF front-end modules in cellular communications typically employ differential phase combining and 90° balanced phase combining.

[0003] Currently, differential structures typically incorporate bulky baluns at both the input and output of power amplifiers, increasing chip and module costs. Furthermore, differential baluns used in 5G communications generally exhibit poor balance, resulting in lower power amplifier stability and isolation. 90° balanced phase combining in 5G communication RF front-ends often employs a transformer-based 90° combining scheme. Similar to the aforementioned differential combining, this scheme incorporates large transformer-based 90° couplers at both the input and output of the power amplifier. Moreover, this 90° coupler lacks impedance transformation capabilities, requiring additional impedance transformation circuitry, thus occupying a significant amount of chip and module area and contributing to higher costs. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention proposes a power combining circuit to solve the problem of high cost in existing power combining circuits.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a power combining circuit, including an input impedance matching circuit, a first harmonic suppression circuit, a second harmonic suppression circuit, a first high-pass filter circuit, a second high-pass filter circuit, and a low-pass filter circuit;

[0007] The first terminal of the input impedance matching circuit serves as the first signal input terminal of the power combining circuit, and the second terminal of the input impedance matching circuit serves as the second signal input terminal of the power combining circuit. The first terminal of the first harmonic suppression circuit is connected to the first terminal of the input impedance matching circuit. The second terminal of the first harmonic suppression circuit is grounded, and the first terminal of the second harmonic suppression circuit is connected to the second terminal of the input impedance matching circuit, and the second terminal of the second harmonic suppression circuit is grounded. The input impedance matching circuit provides power supply and impedance matching. The first harmonic suppression circuit filters out second harmonics from the signal output from the first terminal of the input impedance matching circuit. The second harmonic suppression circuit filters out second harmonics from the signal output from the second terminal of the input impedance matching circuit.

[0008] The input terminal of the first high-pass filter circuit is connected to the first terminal of the first harmonic suppression circuit, and the output terminal of the first high-pass filter circuit is connected to the first input terminal of the low-pass filter circuit. The input terminal of the second high-pass filter circuit is connected to the first terminal of the second harmonic suppression circuit, and the output terminal of the second high-pass filter circuit is connected to the second input terminal of the low-pass filter circuit. The output terminal of the low-pass filter circuit serves as the signal synthesis output terminal of the power combining circuit. The first high-pass filter circuit is used to filter the signal output from the first terminal of the input impedance matching circuit. The second high-pass filter circuit is used to filter the signal output from the second terminal of the input impedance matching circuit. The low-pass filter circuit is used to synthesize and filter the signals output from the first high-pass filter circuit and the second high-pass filter circuit respectively before outputting the result.

[0009] The low-pass filter circuit includes a first inductor, a second inductor, and a first capacitor; the first end of the first inductor serves as the first input terminal of the low-pass filter circuit, the first end of the second inductor serves as the second input terminal of the low-pass filter circuit, the second end of the first inductor is connected to the first end of the first capacitor and the second end of the second inductor respectively and serves as the output terminal of the low-pass filter circuit, and the second end of the first capacitor is grounded.

[0010] Preferably, the first high-pass filter circuit includes a second capacitor and a third inductor; the first terminal of the second capacitor serves as the input terminal of the first high-pass filter circuit, the second terminal of the second capacitor is connected to the first terminal of the third inductor and serves as the output terminal of the first high-pass filter circuit, and the second terminal of the third inductor is grounded;

[0011] The second high-pass filter circuit includes a third capacitor and a fourth inductor; the first terminal of the third capacitor serves as the input terminal of the second high-pass filter circuit, the second terminal of the third capacitor is connected to the first terminal of the fourth inductor and serves as the output terminal of the second high-pass filter circuit, and the second terminal of the fourth inductor is grounded.

[0012] Preferably, the power combining circuit further includes a first resistor; the first end of the first resistor is connected to the output terminal of the first high-pass filter circuit, and the second end of the first resistor is connected to the output terminal of the second high-pass filter circuit.

[0013] Preferably, the input impedance matching circuit includes a voltage source, a fifth inductor, and a sixth inductor; the negative terminal of the voltage source is grounded, and the positive terminal of the voltage source is connected to the first terminal of the fifth inductor and the first terminal of the sixth inductor, respectively; the second terminal of the fifth inductor serves as the first terminal of the input impedance matching circuit; and the second terminal of the sixth inductor serves as the second terminal of the input impedance matching circuit.

[0014] Preferably, the first harmonic suppression circuit includes a fourth capacitor and a seventh inductor; the first terminal of the fourth capacitor serves as the second terminal of the first harmonic suppression circuit, the second terminal of the fourth capacitor is connected to the first terminal of the seventh inductor, and the second terminal of the seventh inductor serves as the first terminal of the first harmonic suppression circuit.

[0015] The second harmonic suppression circuit includes a fifth capacitor and an eighth inductor; the first terminal of the fifth capacitor serves as the second terminal of the second harmonic suppression circuit, and the second terminal of the fifth capacitor is connected to the first terminal of the eighth inductor, which in turn serves as the first terminal of the second harmonic suppression circuit.

[0016] Preferably, the first capacitor is an SMD capacitor or an HBT / SOI on-chip capacitor.

[0017] Secondly, embodiments of the present invention provide a power amplifier, the power amplifier including a signal source, a first amplifier, a second amplifier, and a power combining circuit as described above;

[0018] The first end of the signal source is grounded, and the second end of the signal source outputs radio frequency signals to the input end of the first amplifier and the input end of the second amplifier, respectively. The output end of the first amplifier is connected to the first signal input end, and the output end of the second amplifier is connected to the second signal input end.

[0019] Compared with related technologies, in the embodiments of the present invention, by directly connecting the signal source to the first amplifier and the second amplifier, compared with differential synthesis and 90° synthesis, the input end of the amplifier does not need to be added to any power distribution network, thereby simplifying the input end and reducing chip area and cost. Simultaneously, the outputs of the first and second amplifiers are combined into a single power output via a non-inverting power combining circuit. Furthermore, the first terminal of the input impedance matching circuit serves as the first signal input of the power combining circuit, and the second terminal serves as the second signal input. The first signal input is sequentially connected to the first inputs of the first harmonic suppression circuit, the first high-pass filter circuit, and the low-pass filter circuit. The second signal input is sequentially connected to the second inputs of the second harmonic suppression circuit, the second high-pass filter circuit, and the low-pass filter circuit. The output of the low-pass filter circuit serves as the signal combining output of the power combining circuit. The first terminal of the first inductor of the low-pass filter circuit serves as its first input, and the first terminal of the second inductor serves as its second input. The second terminal of the first inductor is connected to the first terminal of the first capacitor and the second terminal of the second inductor, respectively, and serves as the output of the low-pass filter circuit. The second terminal of the first capacitor is grounded. Through appropriate impedance, filtering, and resonance processing, the power amplifier possesses impedance transformation characteristics, while also offering advantages such as low cost, high isolation, and high integration. Attached Figure Description

[0020] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0021] Figure 1 is a circuit diagram of the power combining circuit provided in Embodiment 1 of the present invention;

[0022] Figure 2 is a schematic diagram of the fundamental impedance matching result of the power combining circuit provided in Embodiment 1 of the present invention;

[0023] Figure 3 is a circuit diagram of the power combining circuit provided in Embodiment 2 of the present invention;

[0024] Figure 4 is a circuit structure block diagram of the power amplifier provided in Embodiment 3 of the present invention.

[0025] Among them, 100 is the power combining circuit, 1 is the input impedance matching circuit, 2 is the first harmonic suppression circuit, 3 is the second harmonic suppression circuit, 4 is the first high-pass filter circuit, 5 is the second high-pass filter circuit, 6 is the low-pass filter circuit, and 200 is the power amplifier. Detailed Implementation

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] Please refer to Figure 1. An embodiment of the present invention provides a power combining circuit 100, including an input impedance matching circuit 1, a first harmonic suppression circuit 2, a second harmonic suppression circuit 3, a first high-pass filter circuit 4, a second high-pass filter circuit 5, and a low-pass filter circuit 6.

[0031] The first terminal of the input impedance matching circuit 1 serves as the first signal input terminal Input1 of the power combining circuit 100, and the second terminal of the input impedance matching circuit 1 serves as the second signal input terminal Input2 of the power combining circuit 100.

[0032] Specifically, the first terminal of the first harmonic suppression circuit 2 is connected to the first terminal of the input impedance matching circuit 1, and the first terminal of the second harmonic suppression circuit 3 is connected to the second terminal of the input impedance matching circuit 1; the input impedance matching circuit 1 is used to provide power supply and impedance matching. The first harmonic suppression circuit 2 is used to filter out second harmonics from the signal output from the first terminal of the input impedance matching circuit 1. The second harmonic suppression circuit 3 is used to filter out second harmonics from the signal output from the second terminal of the input impedance matching circuit 1.

[0033] The input terminal of the first high-pass filter circuit 4 is connected to the first terminal of the first harmonic suppression circuit 2; the output terminal of the first high-pass filter circuit 4 is connected to the first input terminal of the low-pass filter circuit 6. The input terminal of the second high-pass filter circuit 5 is connected to the first terminal of the second harmonic suppression circuit 3; the output terminal of the second high-pass filter circuit 5 is connected to the second input terminal of the low-pass filter circuit 6. The output terminal of the low-pass filter circuit 6 serves as the signal synthesis output terminal (Output) of the power synthesis circuit 100. The first high-pass filter circuit 4 is used to filter the signal output from the first terminal of the input impedance matching circuit 1. The second high-pass filter circuit 5 is used to filter the signal output from the second terminal of the input impedance matching circuit 1. The low-pass filter circuit 6 is used to synthesize and filter the signals output from the first high-pass filter circuit 4 and the second high-pass filter circuit 5 respectively, and then output the filtered signal.

[0034] The low-pass filter circuit 6 includes a first inductor L1, a second inductor L2, and a first capacitor C1. The first end of the first inductor L1 serves as the first input terminal of the low-pass filter circuit 6, and the first end of the second inductor L2 serves as the second input terminal. The second end of the first inductor L1 is connected to both the first end of the first capacitor C1 and the second end of the second inductor L2, serving as the output terminal of the low-pass filter circuit 6. The second end of the first capacitor C1 is grounded. This design allows for high isolation between the two in-phase power combiners over a wide frequency band. Through appropriate impedance, filtering, and resonance processing, the power combining circuit 100 exhibits impedance transformation characteristics and achieves low cost, high isolation, and high integration, while simultaneously enabling the power amplifier circuit 200 to perform in-phase power combining.

[0035] In this embodiment, the first high-pass filter circuit 4 includes a second capacitor C2 and a third inductor L3. The first terminal of the second capacitor C2 serves as the input terminal of the first high-pass filter circuit 4, and the second terminal of the second capacitor C2 is connected to the first terminal of the third inductor L3 and serves as the output terminal of the first high-pass filter circuit 4. The second terminal of the third inductor L3 is grounded. The connection between the second capacitor C2 and the third inductor L3 removes low-frequency components from the signal, allowing high-frequency signals to pass. Its working principle is based on the different frequency responses of the second capacitor C2 and the third inductor L3 to the signal; by removing signals below a certain frequency, high-frequency signals are allowed to pass, achieving the effect of high-pass filtering. The connection between the second capacitor C2 and the third inductor L3 also performs impedance transformation on the passed signal, improving the impedance matching performance of each part of the overall circuit.

[0036] The second high-pass filter circuit 5 includes a third capacitor C3 and a fourth inductor L4. The first terminal of the third capacitor C3 serves as the input terminal of the second high-pass filter circuit 5, and the second terminal of the third capacitor C3 is connected to the first terminal of the fourth inductor L4 and serves as the output terminal of the second high-pass filter circuit 5. The second terminal of the fourth inductor L4 is grounded. Connecting the third capacitor C3 in series and the fourth inductor L4 in parallel removes low-frequency components from the signal, allowing high-frequency signals to pass. The connection of the third capacitor C3 and the fourth inductor L4 also performs impedance transformation on the transmitted signal, improving the impedance matching performance of each part of the overall circuit.

[0037] In this embodiment, the input impedance matching circuit 1 includes a voltage source SRC2, a fifth inductor L5, and a sixth inductor L6. The negative terminal of the voltage source SRC2 is grounded, and the positive terminal of the voltage source SRC2 is connected to the first terminals of the fifth inductor L5 and the sixth inductor L6, respectively. The second terminal of the fifth inductor L5 serves as the first terminal of the input impedance matching circuit 1. The second terminal of the sixth inductor L6 serves as the second terminal of the input impedance matching circuit 1. Specifically, the second terminal of the fifth inductor L5 is connected to the first terminal of the first signal input terminal Input1 and the first terminal of the first harmonic suppression circuit 2, respectively. The second terminal of the sixth inductor L6 is connected to the first terminal of the second signal input terminal Input2 and the first terminal of the second harmonic suppression circuit 3, respectively. Both the fifth inductor L5 and the sixth inductor L6 participate in impedance matching and also act as choke inductors to isolate the DC power supply of the voltage source SRC2 from the radio frequency signal. The voltage source SRC2 supplies power to the entire circuit, and the fifth inductor L5 and the sixth inductor L6 perform impedance matching on the input signal before outputting it.

[0038] In this embodiment, the first harmonic suppression circuit 2 includes a fourth capacitor C4 and a seventh inductor L7. The first terminal of the fourth capacitor C4 serves as the second terminal of the first harmonic suppression circuit 2 and is grounded. The second terminal of the fourth capacitor C4 is connected to the first terminal of the seventh inductor L7, and the second terminal of the seventh inductor L7 serves as the first terminal of the first harmonic suppression circuit 2. The fourth capacitor C4 and the seventh inductor L7 are used to filter out second harmonics, and simultaneously, they also perform impedance matching. This allows the matching signal output from the input impedance matching circuit 1 to perform secondary impedance matching, controlling the second harmonic impedance value of the amplifier load impedance, thus fulfilling the second harmonic impedance requirements of the power amplifier 200.

[0039] Specifically, the second harmonic suppression circuit 3 includes a fifth capacitor C5 and an eighth inductor L8. The first terminal of the fifth capacitor C5 serves as the second terminal of the second harmonic suppression circuit 3 and is grounded. The second terminal of the fifth capacitor C5 is connected to the first terminal of the eighth inductor L8, which serves as the first terminal of the second harmonic suppression circuit 3. The fifth capacitor C5 and the eighth inductor L8 are used to filter out second harmonics, and simultaneously, they also perform impedance matching. This allows the matching signal output from the input impedance matching circuit 1 to perform secondary impedance matching, controlling the second harmonic impedance value of the amplifier load impedance, thus fulfilling the second harmonic impedance requirements of the power amplifier 200.

[0040] In this embodiment, the first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the seventh inductor L7, and the eighth inductor L8 can all be represented by gold wire. The second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 can all be HBT on-chip capacitors.

[0041] In this embodiment, the first capacitor C1 is an SMD capacitor or an on-chip capacitor for HBT / SOI. Therefore, it occupies a very small area of ​​the HBT chip and the RF front-end module, reducing material costs. Figure 2 below is a Smith chart showing the fundamental impedance matching results in the 2.3GHz to 2.7GHz frequency band of mobile communication. It can be seen that the impedance bandwidth is good, matching from 50 ohms to 3 ohms.

[0042] Example 2

[0043] As shown in Figure 3, this embodiment is basically the same as Embodiment 1 above, except that in this embodiment, the power combining circuit 100 further includes a first resistor R1. The first end of the first resistor R1 is connected to the output terminal of the first high-pass filter circuit 4, and the second end of the first resistor R1 is connected to the output terminal of the second high-pass filter circuit 5. By adding the first resistor R1 in parallel between the two paths, it is used to absorb the signal leaked between the two paths, thereby achieving higher isolation. Specifically, the first end of the first resistor R1 is connected to the second end of the third inductor L3, and the second end of the first resistor R1 is connected to the second end of the sixth inductor L6.

[0044] Example 3

[0045] As shown in Figure 4, an embodiment of the present invention provides a power amplifier 200, which includes a signal source SRC1, a first amplifier AMP1, a second amplifier AMP2, and a power combining circuit 100 as described in any one of embodiments one to two above.

[0046] The first terminal of the signal source SRC1 is grounded, and the second terminal of the signal source SRC1 outputs radio frequency signals to the input terminals of the first amplifier AMP1 and the second amplifier AMP2, respectively. The output terminal of the first amplifier AMP1 is connected to the first signal input terminal Input1, and the output terminal of the second amplifier AMP2 is connected to the second signal input terminal Input2. By directly connecting the signal source SRC1 to the first amplifier AMP1 and the second amplifier AMP2, compared with differential combining and 90° combining, no power distribution network needs to be added to the input terminal of the amplifier, simplifying the input terminal and reducing chip area and cost. At the same time, the output terminals of the first amplifier AMP1 and the second amplifier AMP2 are combined and output through the power combining circuit 100.

[0047] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A power combining circuit, characterized in that, It includes an input impedance matching circuit, a first harmonic suppression circuit, a second harmonic suppression circuit, a first high-pass filter circuit, a second high-pass filter circuit, and a low-pass filter circuit; The first terminal of the input impedance matching circuit serves as the first signal input terminal of the power combining circuit, and the second terminal of the input impedance matching circuit serves as the second signal input terminal of the power combining circuit. The first terminal of the first harmonic suppression circuit is connected to the first terminal of the input impedance matching circuit. The second terminal of the first harmonic suppression circuit is grounded, and the first terminal of the second harmonic suppression circuit is connected to the second terminal of the input impedance matching circuit, and the second terminal of the second harmonic suppression circuit is grounded. The input impedance matching circuit provides power supply and impedance matching. The first harmonic suppression circuit filters out second harmonics from the signal output from the first terminal of the input impedance matching circuit. The second harmonic suppression circuit filters out second harmonics from the signal output from the second terminal of the input impedance matching circuit. The input terminal of the first high-pass filter circuit is connected to the first terminal of the first harmonic suppression circuit, and the output terminal of the first high-pass filter circuit is connected to the first input terminal of the low-pass filter circuit; the input terminal of the second high-pass filter circuit is connected to the first terminal of the second harmonic suppression circuit, and the output terminal of the second high-pass filter circuit is connected to the second input terminal of the low-pass filter circuit; the output terminal of the low-pass filter circuit serves as the signal synthesis output terminal of the power combining circuit; the first high-pass filter circuit is used to filter the signal output from the first terminal of the input impedance matching circuit. The second high-pass filter circuit is used to filter the signal output from the second terminal of the input impedance matching circuit; the low-pass filter circuit is used to combine the signals output from the first high-pass filter circuit and the second high-pass filter circuit respectively, and output them after filtering. The low-pass filter circuit includes a first inductor, a second inductor, and a first capacitor; the first end of the first inductor serves as the first input terminal of the low-pass filter circuit, the first end of the second inductor serves as the second input terminal of the low-pass filter circuit, the second end of the first inductor is connected to the first end of the first capacitor and the second end of the second inductor respectively and serves as the output terminal of the low-pass filter circuit, and the second end of the first capacitor is grounded.

2. The power combining circuit according to claim 1, characterized in that, The first high-pass filter circuit includes a second capacitor and a third inductor; the first terminal of the second capacitor serves as the input terminal of the first high-pass filter circuit, the second terminal of the second capacitor is connected to the first terminal of the third inductor and serves as the output terminal of the first high-pass filter circuit, and the second terminal of the third inductor is grounded; The second high-pass filter circuit includes a third capacitor and a fourth inductor; the first terminal of the third capacitor serves as the input terminal of the second high-pass filter circuit, the second terminal of the third capacitor is connected to the first terminal of the fourth inductor and serves as the output terminal of the second high-pass filter circuit, and the second terminal of the fourth inductor is grounded.

3. The power combining circuit according to claim 1 or 2, characterized in that, The power combining circuit further includes a first resistor; the first end of the first resistor is connected to the output terminal of the first high-pass filter circuit, and the second end of the first resistor is connected to the output terminal of the second high-pass filter circuit.

4. The power combining circuit according to claim 1, characterized in that, The input impedance matching circuit includes a voltage source, a fifth inductor, and a sixth inductor; the negative terminal of the voltage source is grounded, and the positive terminal of the voltage source is connected to the first terminal of the fifth inductor and the first terminal of the sixth inductor, respectively; the second terminal of the fifth inductor serves as the first terminal of the input impedance matching circuit; and the second terminal of the sixth inductor serves as the second terminal of the input impedance matching circuit.

5. The power combining circuit according to claim 4, characterized in that, The first harmonic suppression circuit includes a fourth capacitor and a seventh inductor; the first terminal of the fourth capacitor serves as the second terminal of the first harmonic suppression circuit, the second terminal of the fourth capacitor is connected to the first terminal of the seventh inductor, and the second terminal of the seventh inductor serves as the first terminal of the first harmonic suppression circuit. The second harmonic suppression circuit includes a fifth capacitor and an eighth inductor; the first terminal of the fifth capacitor serves as the second terminal of the second harmonic suppression circuit, and the second terminal of the fifth capacitor is connected to the first terminal of the eighth inductor, which in turn serves as the first terminal of the second harmonic suppression circuit.

6. The power combining circuit according to claim 1, characterized in that, The first capacitor is an SMD capacitor or an HBT / SOI on-chip capacitor.

7. A power amplifier, characterized in that, The power amplifier includes a signal source, a first amplifier, a second amplifier, and a power combining circuit as described in any one of claims 1-6; The first end of the signal source is grounded, and the second end of the signal source outputs radio frequency signals to the input end of the first amplifier and the input end of the second amplifier, respectively. The output end of the first amplifier is connected to the first signal input end, and the output end of the second amplifier is connected to the second signal input end.

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