Power amplifier

Abstract

The embodiment of the invention provides a power amplifier which comprises an amplifying circuit used for amplifying a differential signal; the amplifying circuit comprises a first transistor and a second transistor; the first resonance circuit is connected with the output end of the first transistor and the output end of the second transistor; the first inductor is connected with the first resonance circuit and a grounding end; the first inductor and the first resonant circuit form a second resonant circuit; the first resonance circuit and the second resonance circuit are used for suppressing different harmonic waves.

Description

Technical Field

[0001] The present disclosure relates to the field of electronic technology, and relates to but is not limited to a power amplifier. Background Art

[0002] With the development of mobile communication technology, signal modulation methods are becoming more and more complex, the peak to average power ratio (PAPR) is increasing, and the harmonic suppression requirements of power amplifiers are becoming more and more stringent. However, existing power amplifiers still require more components to achieve better harmonic suppression effects, resulting in increased chip area and higher costs. Summary of the invention

[0003] In view of this, an embodiment of the present disclosure provides a power amplifier, including:

[0004] an amplifier circuit, used for amplifying the differential signal; the amplifier circuit comprises a first transistor and a second transistor;

[0005] a first resonant circuit, connecting an output end of the first transistor and an output end of the second transistor;

[0006] A first inductor connects the first resonant circuit and a ground terminal; the first inductor and the first resonant circuit constitute a second resonant circuit; the first resonant circuit and the second resonant circuit are used to suppress different harmonics.

[0007] In some embodiments, the first resonant circuit is used to suppress N-order harmonics, and the second resonant circuit is used to suppress M-order harmonics; wherein N and M are both integers greater than 1, and N is greater than M.

[0008] In some embodiments, the first resonant circuit comprises:

[0009] a first sub-resonance circuit, connecting the output end of the first transistor and the first end of the first inductor;

[0010] a second sub-resonance circuit, connecting the output end of the second transistor and the first end of the first inductor;

[0011] The second end of the first inductor is connected to the ground end.

[0012] In some embodiments, the first sub-resonance circuit includes a first capacitor and a second inductor; a first end of the first capacitor is connected to the output end of the first transistor, a second end of the first capacitor is connected to the first end of the second inductor, and a second end of the second inductor is connected to the first end of the first inductor;

[0013] The second sub-resonance circuit includes a second capacitor and a third inductor; the first end of the second capacitor is connected to the output end of the second transistor, the second end of the second capacitor is connected to the first end of the third inductor, and the second end of the third inductor is connected to the first end of the first inductor.

[0014] In some embodiments, the first sub-resonance circuit and the second sub-resonance circuit are symmetrically arranged, or the first sub-resonance circuit and the second sub-resonance circuit are asymmetrically arranged.

[0015] In some embodiments, the first capacitor and the second capacitor have different capacitance values;

[0016] and / or,

[0017] The second inductor and the third inductor have different inductance values.

[0018] In some embodiments, at least one of the first capacitor and the second capacitor is a variable capacitor;

[0019] and / or,

[0020] At least one of the first inductor, the second inductor, and the third inductor is a variable inductor.

[0021] In some embodiments, the power amplifier further comprises:

[0022] A combiner circuit connects the output end of the first transistor and the output end of the second transistor.

[0023] In some embodiments, the combiner circuit includes a balun; the first resonant circuit, the first inductor and the balun jointly perform impedance matching.

[0024] In some embodiments, the balun includes a primary coil, a secondary coil and a third capacitor; wherein,

[0025] A first end of the primary coil is connected to an output end of the first transistor, and a second end of the primary coil is connected to an output end of the second transistor;

[0026] The first end of the secondary coil serves as the output end of the power amplifier;

[0027] A first end of the third capacitor is connected to the second end of the secondary coil, and a second end of the third capacitor is connected to the ground end.

[0028] In some embodiments, the third capacitor and the secondary coil form a third resonant circuit, and the first resonant circuit, the second resonant circuit and the third resonant circuit are used to suppress different harmonics.

[0029] In some embodiments, the power amplifier further comprises a power supply;

[0030] The power supply is connected to the balun and fed through the balun;

[0031] or,

[0032] The power supply is connected to the output end of the first transistor and the output end of the second transistor via a fourth inductor, and is fed via the fourth inductor.

[0033] In the disclosed embodiment, the first resonant circuit can be equivalent to a capacitor, and the capacitor and the first inductor form a second resonant circuit, and the first resonant circuit and the second resonant circuit are used to suppress different harmonics. In this way, on the one hand, the second resonant circuit reuses the first resonant circuit, thereby effectively reducing the number of components and the occupied area of ​​the power amplifier, which is conducive to reducing manufacturing costs and improving integration; on the other hand, a smaller number of components is conducive to reducing the loss of the power amplifier; on the other hand, the first resonant circuit and the second resonant circuit are used to suppress different harmonics, which is conducive to achieving a better harmonic suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a power amplifier provided by the present disclosure;

[0035] Figure 2 A schematic diagram of another power amplifier provided by the present disclosure;

[0036] Figure 3 A schematic diagram of a first resonant circuit in another power amplifier provided by the present disclosure;

[0037] Figure 4 A circuit diagram of a first resonant circuit in another power amplifier provided by the present disclosure;

[0038] Figure 5 A schematic diagram of another combiner circuit in a power amplifier provided by the present disclosure;

[0039] Figure 6 A circuit diagram of another power amplifier provided by the present disclosure;

[0040] Figure 7 A circuit diagram of yet another power amplifier provided by the present disclosure. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present disclosure, the exemplary embodiments of the present disclosure will be described in more detail below with reference to the relevant drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the specific embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0042] In the following description, a large number of specific details are given to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In some embodiments, in order to avoid confusion with the present disclosure, some technical features known in the art are not described; that is, all features of the actual embodiment may not be described here, and well-known functions and structures may not be described in detail.

[0043] Generally, terms can be understood at least in part from their use in context. For example, depending at least in part on the context, the term "one or more" as used herein can be used to describe any feature, structure or characteristic in a singular sense, or can be used to describe a combination of features, structures or characteristics in a plural sense. Similarly, terms such as "one" or "the" can also be understood to convey singular usage or to convey plural usage, depending at least in part on the context. In addition, the term "based on" can be understood to not necessarily be intended to convey an exclusive set of factors, and can alternatively allow for the presence of additional factors that are not necessarily explicitly described, which also depends at least in part on the context.

[0044] Unless otherwise defined, the purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present disclosure. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0045] In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present disclosure. The preferred embodiments of the present disclosure are described in detail below, but in addition to these detailed descriptions, the present disclosure may also have other implementations.

[0046] like Figure 1As shown, the power amplifier 100 in the prior art includes: transistors 111 and 112, which are respectively used to amplify differential signals RFIN+ and RFIN-; resonant circuits Trap1, Trap2, Tank1, and Tank2, which are respectively used to suppress different harmonics; and balun 150, which is connected to two transistors through a resonant circuit and is used to combine the differential signal. Among them, the resonant circuit Trap1 and the second series resonant circuit Trap2 are used to suppress second-order harmonics, and the resonant circuits Tank1 and Tank2 are used to suppress third-order harmonics.

[0047] In this way, the resonant circuit in the power amplifier 100 can effectively suppress harmonics of various orders, thereby improving the efficiency of the amplifier. However, the series resonant circuit and the parallel resonant circuit in the power amplifier 100 are relatively independently arranged, and the number of inductors and capacitors required is large, which increases the output loss, narrows the bandwidth, increases the chip area, and increases the cost.

[0048] like Figure 2 As shown, an embodiment of the present disclosure provides a power amplifier 200, including: an amplifier circuit 210, used to amplify differential signals RFIN+ and RFIN-; the amplifier circuit 210 includes a first transistor 211 and a second transistor 212; a first resonant circuit 220, connected to the output end of the first transistor 211 and the output end of the second transistor 212; a first inductor L1, connected to the first resonant circuit 220 and the ground end; the first inductor L1 and the first resonant circuit 220 constitute a second resonant circuit 230; the first resonant circuit 220 and the second resonant circuit 230 are used to suppress different harmonics.

[0049] The present disclosure can utilize a power divider circuit ( Figure 2 The first transistor 211 is used to amplify RFIN+, and the second transistor 212 is used to amplify RFIN-. The first transistor 211 and the second transistor 212 can be bipolar junction transistors (Bipolar Junction Transistor, BJT), such as triodes, or field effect transistors (Field Effect Transistor, FET), such as MOS tubes, which are not limited in this application.

[0050] The first resonant circuit 220 can be composed of one or more capacitors and one or more inductors. The first resonant circuit 220 is connected to the output end of the first transistor 211 and the output end of the second transistor 212. The first resonant circuit 220 can resonate at the frequency of the Nth order harmonic (such as the third order harmonic), thereby achieving suppression of the Nth order harmonic, where N is an integer greater than 1.

[0051] The first inductor L1 connects the first resonant circuit 220 and the ground terminal. At this time, the first resonant circuit 220 can be equivalent to a capacitor. The capacitor and the first inductor L1 constitute the second resonant circuit 230, that is, the second resonant circuit 230 reuses the first resonant circuit 220. The second resonant circuit 230 can resonate at the frequency of the M-order harmonic (such as the 2nd-order harmonic), so as to suppress the M-order harmonic, where M is an integer greater than 1, and M is different from N, that is, the first resonant circuit 220 and the second resonant circuit 230 are used to suppress different harmonics.

[0052] In this way, on the one hand, the second resonant circuit 230 reuses the first resonant circuit 220, thereby effectively reducing the number of components and the occupied area of ​​the power amplifier 200, which is beneficial to reducing manufacturing costs and improving integration; on the other hand, the smaller number of components is beneficial to reducing the loss of the power amplifier 200; on the other hand, the first resonant circuit and the second resonant circuit are used to suppress different harmonics, which is beneficial to achieving a better harmonic suppression effect.

[0053] In some embodiments, the first resonant circuit 220 is used to suppress N-order harmonics, and the second resonant circuit 230 is used to suppress M-order harmonics; wherein N and M are both integers greater than 1, and N is greater than M.

[0054] Since the order of the harmonics suppressed by the second resonant circuit 230 is lower than the order of the harmonics suppressed by the first resonant circuit 220, that is, the first resonant circuit 220 is used to suppress higher-order harmonics, the occupied area of ​​the capacitor and the inductor in the first resonant circuit 220 can be smaller, further improving the integration of the power amplifier 200 and reducing the manufacturing cost. For example, the first resonant circuit 220 resonates at the frequency of the 3rd order harmonic, and the second resonant circuit 230 resonates at the frequency of the 2nd order harmonic; for another example, the first resonant circuit 220 resonates at the frequency of the 4th order harmonic, and the second resonant circuit 230 resonates at the frequency of the 2nd order harmonic; for another example, the first resonant circuit 220 resonates at the frequency of the 4th order harmonic, and the second resonant circuit 230 resonates at the frequency of the 3rd order harmonic.

[0055] It is understandable that compared to Figure 1 In the embodiment shown in FIG. 2 , the second resonant circuit 230 not only reuses the first resonant circuit 220, but the first resonant circuit 220 is also used to suppress higher-order harmonics, further reducing the occupied area of ​​the first resonant circuit 220 (the reused part), thereby greatly saving the area of ​​the power amplifier 200.

[0056] In some embodiments, Figure 3As shown, the first resonant circuit 220 includes: a first sub-resonant circuit 221, connecting the output end of the first transistor 211 and the first end of the first inductor L1; a second sub-resonant circuit 222, connecting the output end of the second transistor 212 and the first end of the first inductor L1; and the second end of the first inductor L1 is connected to the ground end.

[0057] The first resonant circuit 220 includes a first sub-resonant circuit 221 and a second sub-resonant circuit 222. The first sub-resonant circuit 221 can be composed of one or more capacitors and one or more inductors, and the second sub-resonant circuit 222 can be composed of one or more capacitors and one or more inductors. The circuit structures of the first sub-resonant circuit 221 and the second sub-resonant circuit 222 can be the same or different.

[0058] The first sub-resonance circuit 221 is used to suppress the N-order harmonics of the output signal of the first transistor 211, and the second sub-resonance circuit 222 is used to suppress the N-order harmonics of the output signal of the second transistor 212. The first sub-resonance circuit 221 and the first inductor L1 can be used to suppress the M-order harmonics of the output signal of the first transistor 211, and the second sub-resonance circuit 222 and the first inductor L1 can be used to suppress the M-order harmonics of the output signal of the second transistor 212. In this way, the N-order harmonics and the M-order harmonics of the differential signals RFIN+ and RFIN- input to the power amplifier 200 can be effectively suppressed, thereby improving the efficiency of the amplifier.

[0059] In some embodiments, Figure 4 As shown, the first sub-resonance circuit 221 includes a first capacitor C1 and a second inductor L2; the first end of the first capacitor C1 is connected to the output end of the first transistor 211, the second end of the first capacitor C1 is connected to the first end of the second inductor L2, and the second end of the second inductor L2 is connected to the first end of the first inductor L1; the second sub-resonance circuit 222 includes a second capacitor C2 and a third inductor L3; the first end of the second capacitor C2 is connected to the output end of the second transistor 212, the second end of the second capacitor C2 is connected to the first end of the third inductor L3, and the second end of the third inductor L3 is connected to the first end of the first inductor L1.

[0060] The first sub-resonance circuit 221 includes a first capacitor C1 and a second inductor L2 connected in series between the output end of the first transistor 211 and the first inductor L1, and the second sub-resonance circuit 222 includes a second capacitor C2 and a third inductor L3 connected in series between the output end of the second transistor 212 and the first inductor L1.

[0061] The first capacitor C1 and the second inductor L2 can resonate at the frequency of the N-order harmonic, thereby suppressing the N-order harmonic of the output signal of the first transistor 211; the second capacitor C2 and the third inductor L3 can resonate at the frequency of the N-order harmonic, thereby suppressing the N-order harmonic of the output signal of the second transistor 212. The first capacitor C1 and the second inductor L2 are equivalent to a capacitor, and the capacitor and the first inductor L1 can resonate at the frequency of the M-order harmonic, thereby suppressing the M-order harmonic of the output signal of the first transistor 211; the second capacitor C2 and the third inductor L3 are equivalent to a capacitor, and the capacitor and the first inductor L1 can resonate at the frequency of the M-order harmonic, thereby suppressing the M-order harmonic of the output signal of the second transistor 212.

[0062] Since N is greater than M, compared with the second resonant circuit 230, the first resonant circuit 220 is used to suppress higher-order harmonics, so the occupied area of ​​the first capacitor C1, the second inductor L2, the third capacitor C3 and the third inductor L3 can be smaller, further improving the integration of the power amplifier 200 and reducing the manufacturing cost.

[0063] In some embodiments, the first sub-resonance circuit and the second sub-resonance circuit are symmetrically arranged, or the first sub-resonance circuit and the second sub-resonance circuit are asymmetrically arranged.

[0064] In the present disclosure, the harmonic suppression points of the first sub-resonance circuit and the second sub-resonance circuit may be the same or different. Exemplarily, the first sub-resonance circuit may have the same elements and connection method as the second sub-resonance circuit, that is, the first sub-resonance circuit and the second sub-resonance circuit are symmetrically arranged, and the harmonic suppression points of the first sub-resonance circuit and the second sub-resonance circuit are the same; the first sub-resonance circuit may have different elements or connection methods from the second sub-resonance circuit, that is, the first sub-resonance circuit and the second sub-resonance circuit are asymmetrically arranged, and the harmonic suppression points of the first sub-resonance circuit and the second sub-resonance circuit are different, thereby improving the flexibility of the power amplifier in suppressing harmonics.

[0065] In some embodiments, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are different; and / or the inductance values ​​of the second inductor L2 and the third inductor L3 are different. In other words, the first sub-resonance circuit 221 and the second sub-resonance circuit 222 are asymmetrically arranged, and the harmonic suppression points of the first sub-resonance circuit 221 and the second sub-resonance circuit 222 are different.

[0066] In some embodiments, the structures of the first sub-resonance circuit and the second sub-resonance circuit may also be different. For example, the first sub-resonance circuit is an LC type filter structure, and the second sub-resonance circuit is a CL type filter structure, or the first sub-resonance circuit is a CL type filter structure, and the second sub-resonance circuit is an LC type filter structure; for another example, the first sub-resonance circuit is a CLC type filter structure, and the second sub-resonance circuit is an LCL type filter structure, or the first sub-resonance circuit is an LCL type filter structure, and the second sub-resonance circuit is a CLC type filter structure; for another example, the first sub-resonance circuit is a CRC type filter structure, and the second sub-resonance circuit is an RCR type filter structure, or the first sub-resonance circuit is an RCR type filter structure, and the second sub-resonance circuit is a CRC type filter structure. It can be understood that the first sub-resonance circuit and the second sub-resonance circuit can be any combination of the same two filter structures or different two filter structures in the filter structures such as LC type, CL type, RC type, CLC type, LCL type, CRC type, RCR type, DLC type, etc., and the present disclosure is not limited.

[0067] In some embodiments, at least one of the first capacitor C1 and the second capacitor C2 is a variable capacitor; and / or at least one of the first inductor L1, the second inductor L2, and the third inductor L3 is a variable inductor. In this way, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be adjusted according to actual needs, and the inductance values ​​of the first inductor L1, the second inductor L2, and the third inductor L3 can be adjusted according to actual needs. Exemplarily, each variable capacitor and each variable inductor in the present disclosure can be adjusted according to the frequency band, power, mode, etc. of the input signal.

[0068] In some embodiments, Figure 5 As shown, the power amplifier 200 also includes: a combiner circuit 240, which is connected to the output end of the first transistor 211 and the output end of the second transistor 212. The combiner circuit 240 is used to combine the two differential signals output by the first transistor 211 and the second transistor 212 into a single-ended output signal. The combiner circuit 240 can be implemented by a balun or other circuits, and the present disclosure does not impose too many restrictions.

[0069] In some embodiments, the combiner circuit 240 includes a balun; the first resonant circuit 220, the first inductor L1 and the balun perform impedance matching together.

[0070] The combiner circuit 240 can combine two differential signals through a balun, thereby achieving a larger bandwidth, and the structure of the balun is simpler, which is conducive to reducing costs. In addition, the first resonant circuit 220, the first inductor L1 and the balun perform impedance matching together, thereby further reducing the loss of the power amplifier 200.

[0071] In some embodiments, Figure 6As shown, the balun includes a primary coil Lpc, a secondary coil Lsc and a third capacitor C3; wherein the first end of the primary coil Lpc is connected to the output end of the first transistor 211, and the second end of the primary coil Lpc is connected to the output end of the second transistor 212; the first end of the secondary coil Lsc serves as the output end of the power amplifier 200; the first end of the third capacitor C3 is connected to the second end of the secondary coil Lsc, and the second end of the third capacitor C3 is connected to the ground end. In this way, by combining and impedance matching the balun, the loss can be further reduced and the bandwidth can be improved.

[0072] In some embodiments, the third capacitor C3 can be set as a variable capacitor, and the capacitance value of the third capacitor C3 can be adjusted according to the frequency band, power, mode, etc. of the input signal.

[0073] In some embodiments, Figure 6 As shown, the third capacitor C3 and the secondary coil Lsc form a third resonant circuit 250, and the first resonant circuit 220, the second resonant circuit 230 and the third resonant circuit 250 are used to suppress different harmonics.

[0074] The third capacitor C3 and the secondary coil Lsc in the balun can also form a third resonant circuit 250, which can be used to suppress P-order harmonics, and P, N and M are different, that is, the first resonant circuit 220, the second resonant circuit 230 and the third resonant circuit 250 are used to suppress different harmonics. Exemplarily, the third resonant circuit 250 is used to suppress 4-order harmonics, the first resonant circuit 220 is used to suppress 3-order harmonics, and the second resonant circuit 230 is used to suppress 2-order harmonics. In this way, the harmonic suppression effect of the power amplifier 200 can be further improved.

[0075] In some embodiments, Figure 6 As shown, the power amplifier also includes a power supply Vcc; the power supply Vcc is connected to the balun and fed through the balun; or, as shown Figure 7 As shown, the power source Vcc is connected to the output end of the first transistor 211 and the output end of the second transistor 212 through the fourth inductor L4, and is fed through the fourth inductor L4.

[0076] In some embodiments, Figure 6As shown, the power supply Vcc is connected to the primary coil Lpc of the balun and is fed through the primary coil Lpc. Among them, the power supply Vcc divides the primary coil Lpc into two parts, and the two parts of the coil are used as the choke inductor of the first transistor 211 and the second transistor 212 respectively, that is, the inductor in the balun is reused, which is used as both a combiner and a choke inductor to avoid interference of the radio frequency signal to the power supply Vcc. It should be noted that the inductance values ​​of the two parts of the coil can be the same or different. In some embodiments, the primary coil Lpc can be set with multiple connection points, and each connection point makes the two choke inductors have different inductance values, so that the power supply Vcc can be connected to one of the connection points as needed. In addition, the power supply Vcc can also reuse other inductors in the balun except the primary coil Lpc, and the present disclosure does not limit this.

[0077] In some embodiments, Figure 7 As shown, the power supply Vcc is connected to the output end of the first transistor 211 through a fourth inductor L4, and is connected to the output end of the second transistor 212 through another fourth inductor L4, so as to be fed through the fourth inductor L4, that is, the two fourth inductors L4 can be used as choke inductors to avoid interference of the radio frequency signal on the power supply Vcc. In other embodiments, the two fourth inductors L4 can also be used for impedance matching, and the inductance values ​​of the two fourth inductors L4 can be the same or different.

[0078] The present disclosure also provides an electronic device, including any power amplifier in the above embodiments. The electronic device includes but is not limited to a mobile phone, a tablet computer, a smart wearable device, etc.

[0079] It should be noted that the features disclosed in several method or device embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0080] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A power amplifier, characterized in that: include: an amplifier circuit, used for amplifying the differential signal; the amplifier circuit comprises a first transistor and a second transistor; a first resonant circuit, connecting an output end of the first transistor and an output end of the second transistor; a first inductor, connecting the first resonant circuit and a ground terminal; the first inductor and the first resonant circuit constitute a second resonant circuit; The first resonant circuit and the second resonant circuit are used to suppress different harmonics.

2. The power amplifier according to claim 1, characterized in that: The first resonant circuit is used to suppress N-order harmonics, and the second resonant circuit is used to suppress M-order harmonics; wherein N and M are both integers greater than 1, and N is greater than M.

3. The power amplifier according to claim 1, characterized in that: The first resonant circuit comprises: a first sub-resonance circuit, connecting the output end of the first transistor and the first end of the first inductor; a second sub-resonance circuit, connecting the output end of the second transistor and the first end of the first inductor; The second end of the first inductor is connected to the ground end.

4. The power amplifier according to claim 3, characterized in that: The first sub-resonance circuit includes a first capacitor and a second inductor; a first end of the first capacitor is connected to the output end of the first transistor, a second end of the first capacitor is connected to the first end of the second inductor, and a second end of the second inductor is connected to the first end of the first inductor; The second sub-resonance circuit includes a second capacitor and a third inductor; the first end of the second capacitor is connected to the output end of the second transistor, the second end of the second capacitor is connected to the first end of the third inductor, and the second end of the third inductor is connected to the first end of the first inductor.

5. The power amplifier according to claim 3, characterized in that: The first sub-resonance circuit and the second sub-resonance circuit are symmetrically arranged, or the first sub-resonance circuit and the second sub-resonance circuit are asymmetrically arranged.

6. The power amplifier according to claim 4, characterized in that: The first capacitor and the second capacitor have different capacitance values; and / or, The second inductor and the third inductor have different inductance values.

7. The power amplifier according to claim 4, characterized in that: At least one of the first capacitor and the second capacitor is a variable capacitor; and / or, At least one of the first inductor, the second inductor, and the third inductor is a variable inductor.

8. The power amplifier according to claim 1, characterized in that: The power amplifier further comprises: A combiner circuit connects the output end of the first transistor and the output end of the second transistor.

9. The power amplifier according to claim 8, characterized in that: The combiner circuit includes a balun; the first resonant circuit, the first inductor and the balun jointly perform impedance matching.

10. The power amplifier according to claim 9, characterized in that: The balun includes a primary coil, a secondary coil and a third capacitor; wherein, A first end of the primary coil is connected to an output end of the first transistor, and a second end of the primary coil is connected to an output end of the second transistor; The first end of the secondary coil serves as the output end of the power amplifier; A first end of the third capacitor is connected to the second end of the secondary coil, and a second end of the third capacitor is connected to the ground end.

11. The power amplifier according to claim 10, characterized in that: The third capacitor and the secondary coil form a third resonant circuit, and the first resonant circuit, the second resonant circuit and the third resonant circuit are used to suppress different harmonics.

12. The power amplifier according to claim 9, characterized in that: The power amplifier also includes a power supply; The power supply is connected to the balun and fed through the balun; or, The power supply is connected to the output end of the first transistor and the output end of the second transistor via a fourth inductor, and is fed via the fourth inductor.

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