Output matching circuit, power amplifier and power amplifier chip

Abstract

The invention discloses an output matching circuit, a power amplifier and a power amplifier chip, relates to the field of amplifiers, and aims to solve the problem that it is difficult to meet the impedance matching requirements of two different frequencies at the same time by sharing an output matching network. The optimal fundamental impedance is used for matching the fundamental impedance of the output end of the amplifier to the drain electrode of the transistor; the first microstrip line is provided with a matching position, and an area from the first end to the matching position in the first microstrip line is a sub-microstrip line; and the harmonic matching assembly comprises a sub-microstrip line and an auxiliary matching module connected with the matching position, and the auxiliary matching module is used for short-circuiting the second harmonic transmitted by the drain electrode of the transistor to the ground at the matching point, so that the second harmonic impedance of the drain electrode of the transistor reaches the optimal second harmonic impedance. According to the invention, the output matching network can match the fundamental wave and the second harmonic wave at the same time, so that the efficiency of the power amplifier is improved.

Description

Technical Field

[0001] The present invention relates to the field of amplifiers, and in particular to an output matching circuit, a power amplifier and a power amplifier chip. Background Art

[0002] With the development of wireless communication technology, power amplifiers are widely used in cellular networks, broadcasting, radar communications and satellite communications. The performance of power amplifiers directly determines the performance of RF transmitters. In the research on improving the efficiency of power amplifiers, although F / F-1 amplifiers can significantly improve the efficiency of power amplifiers, the fundamental wave and higher harmonics of this type of amplifier share the same output matching network. Due to the different frequencies of the fundamental wave and higher harmonics, the shared output matching network is difficult to simultaneously meet the impedance matching requirements of two different frequencies, which is not conducive to improving the efficiency of the power amplifier.

[0003] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Summary of the invention

[0004] The object of the present invention is to provide an output matching circuit, a power amplifier and a power amplifier chip, which can realize the matching of the output matching network to the fundamental wave and the second harmonic at the same time, thereby improving the efficiency of the power amplifier.

[0005] In order to solve the above technical problems, the present invention provides an output matching circuit, comprising:

[0006] A fundamental wave matching component comprising a first microstrip line, used for matching the fundamental wave impedance of the output end of the amplifier to the optimal fundamental wave impedance of the drain of the transistor; the first end of the first microstrip line is connected to the drain of the transistor, the first microstrip line has a matching position, the area from the first end to the matching position in the first microstrip line is a sub-microstrip line, and the length of the sub-microstrip line is determined based on the optimal second harmonic impedance corresponding to the transistor;

[0007] A harmonic matching component includes the sub-microstrip line and an auxiliary matching module connected to the matching position, wherein the auxiliary matching module is used to short-circuit the second harmonic transmitted by the drain of the transistor to the ground at the matching point so that the second harmonic impedance of the drain of the transistor reaches the optimal second harmonic impedance.

[0008] Optionally, the auxiliary matching module includes a first matching element and a first capacitor, a first end of the first matching element and the first capacitor connected in series is connected to the matching position, and a second end of the first matching element and the first capacitor connected in series is grounded.

[0009] Optionally, the first matching element is a second microstrip line or an inductor.

[0010] Optionally, the auxiliary matching module includes an open line, one end of which is connected to the matching position of the microstrip line, and the other end of which remains in an open state.

[0011] Optionally, the fundamental wave matching component also includes a first matching unit and a second matching unit, the first end of the first matching unit is connected to the drain supply voltage, the second end of the first matching unit is respectively connected to the first end of the second matching unit and the second end of the first microstrip line, and the output end of the second matching unit serves as the amplifier output end.

[0012] Optionally, the first matching unit includes a second capacitor and a second matching element, the common end of the first end of the second capacitor and the first end of the second matching element being connected to the drain supply voltage, the second end of the second capacitor being grounded, and the second end of the second matching element serving as the second end of the first matching unit.

[0013] Optionally, the second matching unit includes a third matching element, a third capacitor and a fourth capacitor, the first end of the third matching element serves as the first end of the second matching unit, the first end of the third capacitor is respectively connected to the second end of the third matching element and the first end of the fourth capacitor, and the second end of the fourth capacitor serves as the output end of the second matching unit.

[0014] Optionally, the process of determining the length of the sub-microstrip line based on the optimal second harmonic impedance corresponding to the transistor includes:

[0015] Obtaining an optimal second harmonic impedance corresponding to the transistor, a characteristic impedance and a phase constant of the first microstrip line;

[0016] The length of the sub-microstrip line is calculated based on the optimal second harmonic impedance, the characteristic impedance, and the phase constant.

[0017] In order to solve the above technical problems, the present invention further provides a power amplifier, comprising an input matching circuit, a transistor and an output matching circuit as described in any one of the above.

[0018] To solve the above technical problems, the present invention further provides a power amplifier chip, comprising a transistor and an output matching circuit prepared on the same substrate, wherein the transistor comprises a gate, a drain and a source;

[0019] The output matching circuit includes a fundamental wave matching component and an auxiliary matching module;

[0020] The fundamental wave matching component comprises a first microstrip line, a first end of the first microstrip line is connected to the drain of the transistor, and a second end of the fundamental wave matching component serves as an output end of the power amplifier chip;

[0021] A first end of the auxiliary matching module is connected to the middle position of the first microstrip line, and a second end of the auxiliary matching module is grounded;

[0022] The length from the first end of the first microstrip line to the middle position is determined based on the optimal second harmonic impedance corresponding to the transistor.

[0023] The present invention provides an output matching circuit, wherein a first end of a first microstrip line is connected to a drain of a transistor, a matching position on the first microstrip line is determined based on an optimal second harmonic impedance corresponding to the transistor, an auxiliary matching module is arranged to be connected to the matching position, and the second harmonic is short-circuited to ground at the matching position, so that the second harmonic impedance of the drain of the transistor is moved to the optimal second harmonic impedance, and the auxiliary matching module can short-circuit the second harmonic to ground, that is, the resonant frequency of the auxiliary matching module is consistent with or very close to the frequency of the second harmonic, so the resonant frequency of the auxiliary matching module is far from the fundamental frequency, and is approximately open-circuited to the fundamental, without affecting the transmission of the fundamental, and the fundamental impedance of the output end of the amplifier is matched to the optimal fundamental impedance of the drain of the transistor through a fundamental matching component, so that the output matching network simultaneously matches the fundamental and the second harmonic, thereby improving the efficiency of the power amplifier.

[0024] The present invention also provides a power amplifier and a power amplifier chip, which have the same beneficial effects as the above output matching circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of an output matching circuit provided by the present invention;

[0027] Figure 2 A schematic diagram of the structure of another output matching circuit provided by the present invention;

[0028] Figure 3 A schematic diagram of second harmonic impedance shift of an output matching circuit provided by the present invention;

[0029] Figure 4 This is a schematic diagram of the impedance of an output matching circuit provided by the present invention. DETAILED DESCRIPTION

[0030] The core of the present invention is to provide an output matching circuit, a power amplifier and a power amplifier chip, which can achieve the matching of the output matching network to the fundamental wave and the second harmonic at the same time, thereby improving the efficiency of the power amplifier.

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] First, please refer to Figure 1 , the present invention provides an output matching circuit, comprising:

[0033] A fundamental wave matching component 1 including a first microstrip line 11, which is used to match the fundamental wave impedance of the amplifier output end to the optimal fundamental wave impedance of the drain of the transistor M1; the first end of the first microstrip line 11 is connected to the drain of the transistor M1, the first microstrip line 11 has a matching position, the area from the first end to the matching position in the first microstrip line 11 is a sub-microstrip line, and the length of the sub-microstrip line is determined based on the optimal second harmonic impedance corresponding to the transistor M1;

[0034] The harmonic matching component 2 includes a sub-microstrip line and an auxiliary matching module 21 connected to the matching position. The auxiliary matching module 21 is used to short-circuit the second harmonic transmitted by the drain of the transistor M1 to the ground at the matching point so that the second harmonic impedance of the drain of the transistor M1 reaches the optimal second harmonic impedance.

[0035] In this embodiment, the gate of transistor M1 is connected to the RF input signal ( Figure 1 RFin represents the RF input signal), the RF input signal is amplified and output from the drain of the transistor M1, and the source of the transistor M1 is grounded. The drain of the transistor M1 is connected to a first microstrip line 11, and one end of the first microstrip line 11 connected to the drain of the transistor M1 is a first end of the first microstrip line 11.

[0036] It can be understood that the microstrip line not only serves as a transmission medium to realize the transmission of the signal on the drain of the transistor M1, but also can realize the matching of the fundamental wave and the harmonics in combination with other matching elements (such as capacitors, inductors, etc.). In this embodiment, the auxiliary matching module 21 cooperates with microstrip lines of different lengths, and can also short-circuit the second harmonic output from the drain of the transistor M1 to the ground, so as to achieve second harmonic impedance matching. Specifically, this embodiment reuses the first microstrip line 11, divides a section of sub-microstrip line on the first microstrip line 11 to cooperate with the auxiliary matching module 21, and one end of the sub-microstrip line is the first end of the first microstrip line 11, and then determines the length of the sub-microstrip line used to cooperate with the auxiliary matching module 21 based on the optimal second harmonic impedance corresponding to the transistor M1 ( Figure 1 After the length of the sub-microstrip line is determined, the other end of the sub-microstrip line is also determined, and the position of the other end of the sub-microstrip line on the first microstrip line 11 is the matching position in this embodiment, that is, Figure 1 Point A on.

[0037] The resonant frequency of the auxiliary matching module 21 is set to be the same as or close to the second harmonic frequency. After the auxiliary matching module 21 is connected to the matching position, the auxiliary matching module 21 provides a short-circuit condition at the second harmonic frequency. It can be understood that at the second harmonic frequency, the impedance of the matching position is very low, close to 0. Therefore, when the drain of the transistor M1 outputs the second harmonic, when the second harmonic is transmitted to the matching position along the sub-microstrip line, the auxiliary matching module 21 effectively short-circuits the second harmonic to the ground at the matching position. By short-circuiting the second harmonic at the matching position, the drain of the transistor M1 ( Figure 1 The second harmonic impedance at point B in the middle is optimized to achieve the optimal second harmonic impedance. This optimization helps to reduce the impact of the second harmonic on the amplifier performance, improve the linearity of the amplifier, reduce distortion, and improve overall efficiency.

[0038] Since the resonant frequency of the auxiliary matching module 21 is set to be the same as or close to the second harmonic frequency, and is far away from the fundamental frequency, the auxiliary matching module 21 will not be in a resonant state at the fundamental frequency, and the impedance at the fundamental frequency is high. Therefore, the auxiliary matching module 21 is approximately open circuit to the fundamental wave, and the fundamental wave impedance will not change.

[0039] The output matching circuit in this embodiment also includes a fundamental matching component 1, which includes a first microstrip line 11. The fundamental impedance of the amplifier output end is matched to the optimal fundamental impedance of the drain of the transistor M1 through the fundamental matching component 1. It can be understood that the second harmonic output from the drain of the transistor M1 and the fundamental share a microstrip line (i.e., a sub-microstrip line) of a specific length for transmission. When the fundamental and second harmonics are transmitted to the matching position along the first microstrip line 11, the auxiliary matching module 21 short-circuits the second harmonic to the ground, so that the second harmonic impedance of the drain of the transistor M1 reaches the optimal second harmonic impedance. The fundamental continues to be transmitted backward along the first microstrip line 11 to perform fundamental impedance matching. Therefore, the output matching circuit in this embodiment can match the fundamental and second harmonics at the same time, which not only suppresses the second harmonics, but also maintains good transmission of the fundamental signal.

[0040] It can be seen that in this embodiment, the first end of the first microstrip line 11 is connected to the drain of the transistor M1, and the matching position on the first microstrip line 11 is determined based on the optimal second harmonic impedance corresponding to the transistor M1, and an auxiliary matching module 21 is set to be connected to the matching position, and the second harmonic is short-circuited to the ground at the matching position, so that the second harmonic impedance of the drain of the transistor M1 is moved to the optimal second harmonic impedance, and the auxiliary matching module 21 can short-circuit the second harmonic to the ground, that is, the resonant frequency of the auxiliary matching module 21 is consistent with or very close to the frequency of the second harmonic, so the resonant frequency of the auxiliary matching module 21 is far from the fundamental frequency, and the fundamental is approximately open-circuited, which does not affect the fundamental transmission, and the fundamental impedance of the amplifier output end is matched to the optimal fundamental impedance of the drain of the transistor M1 through the fundamental matching component 1, so that the output matching network can simultaneously match the fundamental and second harmonics, thereby improving the efficiency of the power amplifier. The present invention also provides a power amplifier having the same beneficial effects as the above-mentioned output matching circuit.

[0041] Reference Figure 2 As shown, the output matching circuit is based on the above embodiment:

[0042] In an exemplary embodiment, the auxiliary matching module 21 includes a first matching element 211 and a first capacitor C1, a first end of the first matching element 211 and the first capacitor C1 connected in series is connected to the matching position, and a second end of the first matching element 211 and the first capacitor C1 connected in series is grounded.

[0043] In this embodiment, the auxiliary matching module 21 mainly includes a first capacitor C1 and a first matching element 211, and the first capacitor C1 and the first matching element 211 are connected in series to enable the harmonic matching component 2 to achieve resonance at a specific frequency. As an optional embodiment, the first end of the first matching element 211 is connected to the matching position, and the second end of the first matching element 211 is connected to the first end of the first capacitor C1. The first capacitor C1 is grounded to effectively adjust the characteristic impedance of the first matching element 211 so as to achieve resonance at a specific frequency. Of course, the first matching element 211 can also be grounded according to actual engineering needs.

[0044] In an exemplary embodiment, the first matching element 211 is a second microstrip line or an inductor.

[0045] In this embodiment, the first matching element 211 can be a microstrip line, an inductor or other element for achieving impedance matching. When a microstrip line is selected as the first matching element 211, the microstrip line can provide a wider frequency range, and the width, length and dielectric constant of the microstrip line can be accurately adjusted to achieve the desired resonant frequency. In addition, the microstrip line is small in size and easy to integrate. When an inductor is selected as the first matching element 211, since the values ​​of the inductor and the capacitor are relatively stable and are less affected by external factors such as temperature and frequency, the resonant frequency of the harmonic matching component 2 has good stability. By selecting different inductor and capacitor values, resonances of different frequencies can be easily achieved to meet different application requirements. Broadband matching can also be achieved, which is suitable for processing broadband signals. The type of the first matching element 211 can be selected according to the actual application requirements and circuit design requirements. This embodiment does not limit the type of the first matching element 211.

[0046] In an exemplary embodiment, the auxiliary matching module 21 includes an open line, one end of the open line is connected to the matching position of the microstrip line, and the other end of the open line remains in an open circuit state.

[0047] In this embodiment, in addition to using the auxiliary matching module 21 constructed by the first matching element 211 and the first capacitor C1, an open line can also be connected to the matching position so that the matching position forms a short-circuit point for the second harmonic. Specifically, one end of the open line is connected to the matching position, and the other end remains in an open state. As an optional embodiment, the width of the open line is the same as the width of the first microstrip line 11, so that the two have the same characteristic impedance, and the length of the open line can be determined according to the second harmonic frequency to achieve the best short-circuit effect for the second harmonic frequency.

[0048] In an exemplary embodiment, the fundamental wave matching component 1 also includes a first matching unit and a second matching unit, the first end of the first matching unit is connected to the drain supply voltage, the second end of the first matching unit is respectively connected to the first end of the second matching unit and the second end of the first microstrip line 11, and the output end of the second matching unit serves as the amplifier output end.

[0049] In this embodiment, the fundamental wave matching component 1 includes not only the first microstrip line 11, but also a first matching unit and a second matching unit, wherein the first matching unit is used to adjust the output impedance of the drain of the transistor M1 to match the characteristic impedance of the first microstrip line 11, thereby reducing signal reflection and loss at the fundamental wave frequency. Of course, the first matching unit can also provide a certain filtering effect. The first end of the second matching unit is connected to the second end of the first matching unit to form a continuous matching network. The second matching unit further adjusts the signal impedance output from the first matching unit to ensure that it matches the optimal fundamental wave impedance of the transistor M1, thereby maximizing the power transmission efficiency.

[0050] In an exemplary embodiment, the first matching unit includes a second capacitor C2 and a second matching element 12, a common end after the first end of the second capacitor C2 is connected to the first end of the second matching element 12 is connected to the drain supply voltage, the second end of the second capacitor C2 is grounded, and the second end of the second matching element 12 serves as the second end of the first matching unit.

[0051] In this embodiment, the combination of the second matching element 12 and the second capacitor C2 forms a matching network for optimizing the output impedance matching of the drain of the transistor M1. The first end of the second capacitor C2 is connected to the drain supply voltage, and the second end is grounded, which can play a filtering role, remove the high-frequency noise on the power line, thereby purifying the drain supply voltage, and will not cause a short circuit to the fundamental signal, thereby reducing the impact on the operation of the transistor M1. Since the second capacitor C2 presents a low impedance to high-frequency signals (such as second harmonics), it is convenient to lead the high-frequency noise from the drain supply voltage to the ground, thereby further reducing the propagation of high-frequency noise in the circuit.

[0052] The first end of the second matching element 12 is connected to the first end of the second capacitor C2, and is used to adjust the impedance of the fundamental frequency. Specifically, the output impedance of the transistor M1 is adjusted to an intermediate value, which is closer to the impedance that the second matching unit can handle. The second matching unit further adjusts the intermediate impedance value to match the optimal fundamental impedance.

[0053] The second matching element 12 may be an inductor, a microstrip line or other elements, which may be selected according to actual engineering needs, and is not limited in this embodiment.

[0054] In an exemplary embodiment, the second matching unit includes a third matching element 13, a third capacitor C3 and a fourth capacitor C4, the first end of the third matching element 13 serves as the first end of the second matching unit, the first end of the third capacitor C3 is respectively connected to the second end of the third matching element 13 and the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 serves as the output end of the second matching unit.

[0055] In this embodiment, the first end of the second matching unit is connected to the second end of the first matching unit, so as to further adjust the adjusted intermediate impedance value of the first matching unit to match the optimal fundamental impedance. The first end of the third capacitor C3 is connected to the second end of the third matching element 13 and the first end of the fourth capacitor C4. Such a configuration helps to further adjust the fundamental impedance. The second capacitor C2, the third capacitor C3 and the fourth capacitor C4 provide filtering at the fundamental frequency to remove noise and interference.

[0056] The first matching unit and the second matching unit jointly achieve matching of the fundamental impedance at the output end of the amplifier to the optimal fundamental impedance corresponding to the transistor M1 through a series of impedance transformations and filtering, thereby improving the performance and efficiency of the entire amplification system.

[0057] In an exemplary embodiment, the process of determining the length of the sub-microstrip line of the first microstrip line 11 of the transistor M1 based on the optimal second harmonic impedance corresponding to the transistor M1 includes:

[0058] Obtaining the optimal second harmonic impedance corresponding to the transistor M1, the characteristic impedance and the phase constant of the first microstrip line 11;

[0059] The length of the sub-microstrip line 11 is calculated based on the optimal second harmonic impedance, the characteristic impedance and the phase constant.

[0060] In this embodiment, the distance between the matching position and the first end of the first microstrip line 11, that is, the length L of the sub-microstrip line, is calculated based on the following relationship. First, the optimal second harmonic impedance, the characteristic impedance of the first microstrip line 11, and the phase constant are obtained. The optimal second harmonic impedance Z opt satisfy , , from which we can get:

[0061] ;

[0062] Where β is the phase constant, , is the wavelength of the second harmonic, and Z0 is the characteristic impedance of the first microstrip line 11. Figure 2 , the second harmonic impedance at point A is as follows Figure 3As shown in FIG. 1 , after a common sub-microstrip line of length L, the second harmonic impedance at point B moves to the optimal second harmonic impedance. The impedance diagram of the output matching circuit is shown in FIG. Figure 4 shown.

[0063] In summary, the solution provided by the present invention can match the matching circuit to the second harmonic optimal impedance without changing the fundamental impedance matching circuit elements, thereby improving the efficiency of the power amplifier.

[0064] In a second aspect, the present invention further provides a power amplifier, comprising an input matching circuit, a transistor, and an output matching circuit as described in any one of the above embodiments.

[0065] For an introduction to a power amplifier provided by the present invention, please refer to the above-mentioned embodiment, and the present invention will not be described in detail here.

[0066] A power amplifier provided by the present invention has the same beneficial effects as the above-mentioned output matching circuit.

[0067] In a third aspect, the present invention further provides a power amplifier chip, comprising a transistor and an output matching circuit prepared on the same substrate, wherein the transistor comprises a gate, a drain and a source;

[0068] The output matching circuit includes a fundamental wave matching component and an auxiliary matching module;

[0069] The fundamental wave matching component comprises a first microstrip line, a first end of the first microstrip line is connected to the drain of the transistor, and a second end of the fundamental wave matching component serves as an output end of the power amplifier chip;

[0070] A first end of the auxiliary matching module is connected to the middle position of the first microstrip line, and a second end of the auxiliary matching module is grounded;

[0071] The length from the first end to the middle position of the first microstrip line is determined based on the optimal second harmonic impedance corresponding to the transistor.

[0072] In this embodiment, the transistor is the core of the power amplifier chip and is responsible for amplifying the signal. The transistor includes a gate, a drain and a source. The output matching circuit is used to ensure that the output impedance of the transistor matches the load impedance to maximize the power transmission efficiency. The fundamental matching component includes a first microstrip line, the first end of the first microstrip line is connected to the drain of the transistor, and is used to match the output impedance of the transistor with the system load impedance. The auxiliary matching module is used to deal with the second harmonic problem of the transistor when it is working. The first end of the auxiliary matching module is connected to the middle position of the first microstrip line, and the second end of the auxiliary matching module is grounded. Through the length and characteristics of the first microstrip line, the fundamental matching component can adjust the output impedance of the transistor to match the system load, thereby improving the power transmission efficiency. The length from the first end to the middle position of the first microstrip line is determined based on the optimal second harmonic impedance corresponding to the transistor, which can effectively suppress the second harmonic, reduce nonlinear distortion, and improve the linearity of the signal. The transistor and the output matching circuit are prepared on the same substrate, which can reduce the length of the signal path, reduce parasitic effects, and improve the overall circuit performance. Through the grounded auxiliary matching module, the high-frequency response can be further optimized, the harmonic component can be reduced, and the working efficiency and reliability of the power amplifier chip can be improved. Through this design, the power amplifier chip can provide efficient power amplification under high-frequency operation while maintaining signal clarity and linearity, and is suitable for various wireless communication devices such as mobile phones, wireless network equipment and other RF communication systems.

[0073] Of course, the transistors and the output matching circuits may also be fabricated on different substrates, which can be selected based on the actual manufacturing process, design requirements, cost considerations, and application scenarios, and this embodiment does not make any specific limitations here.

[0074] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0075] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An output matching circuit, characterized in that: include: A fundamental wave matching component including a first microstrip line, used for matching the fundamental wave impedance of the amplifier output end to the optimal fundamental wave impedance of the drain of the transistor; The first end of the first microstrip line is connected to the drain of the transistor, the first microstrip line has a matching position, the area from the first end to the matching position in the first microstrip line is a sub-microstrip line, and the length of the sub-microstrip line is determined based on the optimal second harmonic impedance corresponding to the transistor; A harmonic matching component includes the sub-microstrip line and an auxiliary matching module connected to the matching position, wherein the auxiliary matching module is used to short-circuit the second harmonic transmitted by the drain of the transistor to the ground at the matching point so that the second harmonic impedance of the drain of the transistor reaches the optimal second harmonic impedance.

2. The output matching circuit according to claim 1, characterized in that: The auxiliary matching module includes a first matching element and a first capacitor, wherein a first end of the first matching element and the first capacitor connected in series is connected to the matching position, and a second end of the first matching element and the first capacitor connected in series is grounded.

3. The output matching circuit according to claim 2, characterized in that: The first matching element is a second microstrip line or an inductor.

4. The output matching circuit according to claim 1, characterized in that: The auxiliary matching module includes an open line, one end of which is connected to the matching position of the microstrip line, and the other end of which remains in an open state.

5. The output matching circuit according to claim 1, characterized in that: The fundamental wave matching component also includes a first matching unit and a second matching unit, the first end of the first matching unit is connected to the drain supply voltage, the second end of the first matching unit is respectively connected to the first end of the second matching unit and the second end of the first microstrip line, and the output end of the second matching unit serves as the amplifier output end.

6. The output matching circuit according to claim 5, characterized in that: The first matching unit includes a second capacitor and a second matching element, the common end of the first end of the second capacitor and the first end of the second matching element being connected is connected to the drain supply voltage, the second end of the second capacitor is grounded, and the second end of the second matching element serves as the second end of the first matching unit.

7. The output matching circuit according to claim 5, characterized in that: The second matching unit includes a third matching element, a third capacitor and a fourth capacitor. The first end of the third matching element serves as the first end of the second matching unit. The first end of the third capacitor is respectively connected to the second end of the third matching element and the first end of the fourth capacitor. The second end of the fourth capacitor serves as the output end of the second matching unit.

8. The output matching circuit according to any one of claims 1 to 7, characterized in that: The process of determining the length of the sub-microstrip line based on the optimal second harmonic impedance corresponding to the transistor includes: Obtaining an optimal second harmonic impedance corresponding to the transistor, a characteristic impedance and a phase constant of the first microstrip line; The length of the sub-microstrip line is calculated based on the optimal second harmonic impedance, the characteristic impedance, and the phase constant.

9. A power amplifier, characterized in that: The invention comprises an input matching circuit, a transistor and an output matching circuit as claimed in any one of claims 1 to 8.

10. A power amplifier chip, characterized in that: The invention comprises a transistor and an output matching circuit prepared on the same substrate, wherein the transistor comprises a gate, a drain and a source; The output matching circuit includes a fundamental wave matching component and an auxiliary matching module; The fundamental wave matching component comprises a first microstrip line, a first end of the first microstrip line is connected to the drain of the transistor, and a second end of the fundamental wave matching component serves as an output end of the power amplifier chip; A first end of the auxiliary matching module is connected to the middle position of the first microstrip line, and a second end of the auxiliary matching module is grounded; The length from the first end of the first microstrip line to the middle position is determined based on the optimal second harmonic impedance corresponding to the transistor.

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