Impedance matching circuit, radio frequency circuit and radio frequency front-end module

Abstract

The utility model provides an impedance matching circuit, a radio frequency circuit and a radio frequency front-end module, the impedance matching circuit comprises a first balun and a first inductor, and the first balun comprises a primary coil and a secondary coil which are coupled with each other; a primary coil of the first balun is used for connecting a differential power amplification circuit; one end of a secondary coil of the first balun is connected to the first inductor, and the other end is grounded; the impedance of the first inductor and the impedance conversion ratio of the first balun are in positive correlation. Through the impedance matching circuit, the impedance fluctuation of the differential power amplification circuit under a broadband can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of radio frequency technology, and in particular to an impedance matching circuit, a radio frequency circuit and a radio frequency front-end module. Background Art

[0002] In the field of radio frequency technology, differential power amplifier circuit is one of the important components. Differential power amplifier circuit is an electronic circuit that amplifies the power of differential radio frequency input signal. However, in the related art, the impedance fluctuation of differential power amplifier circuit under broadband is large, which affects the impedance matching of the overall circuit. Therefore, how to reduce the impedance fluctuation of differential power amplifier circuit under broadband has become an urgent problem to be solved. Utility Model Content

[0003] The main purpose of the present application is to provide an impedance matching circuit, by which the impedance fluctuation of a differential power amplifier circuit under broadband can be effectively reduced.

[0004] In a first aspect, the present application provides an impedance matching circuit, the impedance matching circuit being connected to a differential power amplifier circuit and configured to perform impedance matching on a radio frequency signal output by the differential power amplifier circuit;

[0005] The impedance matching circuit includes a first balun and a first inductor, wherein the first balun includes a primary coil and a secondary coil coupled with each other;

[0006] The primary coil of the first balun is used to connect to the differential power amplifier circuit;

[0007] One end of the secondary coil of the first balun is connected to the first inductor, and the other end is grounded;

[0008] The impedance of the first inductor is positively correlated with the impedance conversion ratio of the first balun.

[0009] In one embodiment, the relationship between the input impedance of the impedance matching circuit and the load impedance of the impedance matching circuit is: Z1=(jwL+Z2) / N;

[0010] Among them, Z1 represents the input impedance of the impedance matching circuit, j is an imaginary unit, w represents the angular frequency of the RF signal, L represents the inductance of the first inductor, jwL is the impedance of the first inductor to the RF signal, Z2 represents the load impedance of the impedance matching circuit, and N represents the impedance conversion ratio of the first balun.

[0011] In one embodiment, the impedance matching circuit further includes a first capacitor, and the first capacitor and the first inductor are connected in parallel to resonate at a set resonant frequency.

[0012] In one embodiment, the set resonant frequency is X times the operating frequency of the differential power amplifier circuit, where X≥2 and is an integer.

[0013] In one embodiment, the impedance matching circuit further includes a first series resonant circuit and a second series resonant circuit; the first series resonant circuit includes a second inductor and a second capacitor connected in series, and the second series resonant circuit includes a third inductor and a third capacitor connected in series;

[0014] The first end of the first series resonant circuit is connected to the first end of the primary coil, and the second end of the first series resonant circuit is grounded; the first end of the second series resonant circuit is connected to the second end of the primary coil, and the second end of the second series resonant circuit is grounded.

[0015] In one embodiment, the impedance matching circuit further includes a matching capacitor; and the other end of the secondary coil is grounded through the matching capacitor.

[0016] In a second aspect, the embodiment of the present application further provides a radio frequency circuit, characterized in that it includes:

[0017] A differential power amplifier circuit; and

[0018] As in any one of the embodiments of the present application, the impedance matching circuit is connected to a differential power amplifier circuit.

[0019] In one embodiment, the differential power amplifier circuit includes a first power amplifier unit and a second power amplifier unit;

[0020] The input end of the first power amplifier unit is used to receive a first radio frequency input signal, and the output end of the first power amplifier unit serves as a first output end of the differential power amplifier circuit;

[0021] The input end of the second power amplifier unit is used to receive a second radio frequency input signal, and the output end of the second power amplifier unit serves as a second output end of the differential power amplifier circuit.

[0022] In one embodiment, the differential power amplifier circuit is integrated on a chip, and the first balun and the first inductor in the impedance matching circuit are arranged on a substrate.

[0023] In a third aspect, an embodiment of the present application further provides a radio frequency front-end module, comprising the radio frequency circuit described in any one of the embodiments of the present application.

[0024] The impedance matching circuit provided in the present application includes a first balun and a first inductor, and the impedance of the first inductor is positively correlated with the impedance conversion ratio of the first balun, thereby compensating for the impedance fluctuation of the impedance seen from the input of the impedance matching circuit with the signal frequency. Among them, the greater the impedance conversion ratio of the first balun to the higher frequency RF signal, the lower the impedance of the impedance matching circuit. And the first inductor can produce a higher impedance to the higher frequency RF signal, the higher the impedance of the impedance matching circuit. Therefore, the first inductor can compensate for the impedance fluctuation problem caused by the change of the first balun with the signal frequency, so that the impedance change of the impedance matching circuit under broadband is smaller and the impedance is flatter, so that the impedance fluctuation of the differential power amplifier output matching under broadband can be reduced, resulting in uneven output power. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A circuit diagram of an implementation of an impedance matching circuit provided in an embodiment of the present application;

[0027] Figure 2 A circuit diagram of another implementation of the impedance matching circuit provided in an embodiment of the present application;

[0028] Figure 3 A circuit diagram of another implementation of the impedance matching circuit provided in an embodiment of the present application;

[0029] Figure 4 A circuit diagram of another implementation of the impedance matching circuit provided in an embodiment of the present application;

[0030] Figure 5 A circuit diagram of another implementation of the impedance matching circuit provided in an embodiment of the present application;

[0031] Figure 6 An impedance simulation diagram of an impedance matching circuit provided in an embodiment of the present application;

[0032] Figure 7 A circuit diagram of an implementation of a radio frequency circuit provided in an embodiment of the present application;

[0033] Figure 8 A circuit diagram of a differential power amplifier circuit provided in an embodiment of the present application;

[0034] Fig. 9A circuit diagram of another implementation of the radio frequency circuit provided in an embodiment of the present application;

[0035] Fig.10 A schematic diagram of the structure of the RF front-end module provided in an embodiment of the present application.

[0036] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0039] Please refer to Figure 1 , Figure 1 A circuit diagram of an implementation of an impedance matching circuit provided in an embodiment of the present application.

[0040] The impedance matching circuit 100 is connected to the differential power amplifier circuit 10 , and the impedance matching circuit 100 is used to perform impedance matching on the radio frequency signal output by the differential power amplifier circuit 10 .

[0041] like Figure 1 As shown, the impedance matching circuit 100 includes a first balun 110 and a first inductor 120 .

[0042] The first balun 110 includes a primary coil and a secondary coil coupled to each other. The primary coil of the first balun 110 is used to connect to the differential power amplifier circuit 10. One end of the secondary coil of the first balun 110 is connected to the first inductor 120, and the other end is grounded. The first balun 110 is used to perform impedance conversion on the RF signal output by the differential power amplifier circuit 10.

[0043] The impedance of the first inductor 120 is positively correlated with the impedance conversion ratio of the first balun 110 , so that when the load impedance remains unchanged, the input impedance of the impedance matching circuit 100 is compensated for fluctuations of the signal frequency.

[0044] It should be noted that the impedance conversion ratio of the first balun 110 refers to the ratio of the impedance values ​​of the secondary coil and the primary coil to the RF signal. For example, if the impedance of the primary coil of the first balun 110 to the RF signal is Z0, and the impedance of the secondary coil of the first balun 110 to the RF signal is N*Z0, then the impedance conversion ratio of the first balun 110 is N.

[0045] For ease of description, the present application refers to the input impedance of the impedance matching circuit 100 as Z1, and the load impedance of the impedance matching circuit 100 as Z2. The impedance matching circuit 100 is used to convert the load impedance Z2 into the input impedance Z1 so that the input impedance Z1 of the impedance matching circuit 100 and the load impedance of the differential power amplifier circuit 10 achieve optimal power matching.

[0046] Since the impedance conversion ratio of the balun itself will fluctuate with the change of the signal frequency, the impedance conversion ratio of the first balun 110 is larger under high-frequency signals. Assuming that the load impedance (e.g., 50Ω) of the impedance matching circuit 100 remains unchanged, the impedance conversion ratio of the first balun 110 becomes larger, which makes the input impedance Z1 of the impedance matching circuit 100 lower. When the bandwidth of the working frequency band is large, the fluctuation of the input impedance Z1 is more obvious, making the output power uneven.

[0047] Therefore, the impedance of the first inductor 120 is set to be positively correlated with the impedance conversion ratio of the first balun 110. Specifically, the impedance conversion ratio of the first balun 110 to the higher frequency RF signal is greater, and the corresponding input impedance Z1 is lower; and the first inductor 120 can produce a higher impedance to the higher frequency RF signal, and the corresponding input impedance Z1 is higher, so that the first inductor 120 can compensate for the impedance fluctuation caused by the impedance conversion ratio of the first balun 110 changing with the signal frequency, so that the impedance change of the overall circuit under broadband is smaller and the impedance is flatter.

[0048] Exemplarily, the relationship between the impedance of the first inductor 120 and the impedance conversion ratio of the first balun 110 is: Z1=(jwL+Z2) / N. Wherein, Z1 represents the input impedance of the impedance matching circuit 100, Z2 represents the load impedance of the impedance matching circuit 100, and N represents the impedance conversion ratio of the first balun 110. j is an imaginary unit, w represents the angular frequency of the RF signal output by the differential power amplifier circuit 10, and the angular frequency of the RF signal w=2πf, and f represents the signal frequency of the RF signal. L represents the inductance value of the first inductor 120.

[0049] In actual circuit design, the impedance conversion ratio N of the first balun 110 increases with the increase of signal frequency, so that the input impedance becomes lower under the same load impedance. The impedance of the first inductor 120 is jwL=j*2πf, which increases with the increase of signal frequency, thereby compensating for the frequency characteristics of the first balun 110 itself, that is, compensating for the impedance non-convergence problem caused by the change of signal frequency of the first balun 110.

[0050] It is understandable that when the impedance matching circuit 100 further includes other components, the relationship between the input impedance and the load impedance of the impedance matching circuit 100 can also be adjusted accordingly. For example, when the first inductor 120 is connected in parallel with a capacitor or in series with other inductors, the impedance jwL of the first inductor is adjusted to the impedance of the first inductor 120 connected in parallel with the capacitor, or the impedance of the first inductor 120 connected in series with other inductors. Among them, the impedance of the first inductor 120 is still positively correlated with the impedance conversion ratio of the first balun 110, and the impedance fluctuation caused by the first balun 110 can still be compensated.

[0051] Generally speaking, the impedance conversion ratio of the balun is roughly the square of the turns ratio, and fluctuates with the change of the signal frequency. Therefore, the impedance conversion ratio of the first balun 110 is positively correlated with the turns ratio of the first balun 110. In some embodiments, the inductance value of the first inductor 120 and the turns ratio of the first balun 110 can be set according to the load impedance of the differential power amplifier circuit 10 and the input impedance of the subsequent circuit of the impedance matching circuit 100, so that the first inductor 120 is used to compensate for the impedance non-convergence problem of the first balun 110 caused by the change of the signal frequency, thereby reducing the impedance fluctuation of the overall circuit to the high-frequency signal, so that the impedance change amount under broadband is smaller and the impedance is flatter.

[0052] In one embodiment, if Figure 2 As shown, the impedance matching circuit 100 also includes a first capacitor 130, and the first capacitor 130 and the first inductor 120 are connected in parallel to resonate at a set resonant frequency. The parallel resonant first capacitor 130 and the first inductor 120 form a parallel resonant circuit, which can present a high impedance to a signal close to its resonant frequency to suppress its output. Optionally, the set resonant frequency can be configured as a harmonic frequency of the differential power amplifier circuit 10, thereby achieving harmonic suppression.

[0053] It should be noted that the resonant frequency can be flexibly set to the harmonic frequency band that needs to be suppressed according to actual conditions. For example, the resonant frequency can be set to X times the operating frequency of the differential power amplifier circuit 10, where X ≥ 2 and is an integer. In this way, a better harmonic suppression effect can be achieved. Exemplarily, the parallel resonant circuit is mainly used for third-order / fourth-order harmonic suppression.

[0054] Specifically, based on the setting of the resonant frequency, the capacitance of the first capacitor 130 is negatively correlated with the inductance of the first inductor 120. Exemplarily, the relationship between the inductance of the first inductor 120 and the capacitance of the first capacitor 130 is: Wherein, f0 represents the set resonant frequency, L represents the inductance of the first inductor 120 , and C represents the capacitance of the first capacitor 130 .

[0055] After the inductance of the first inductor 120 is determined according to the required input impedance Z1 and the impedance conversion ratio of the first balun 110, the capacitance of the first capacitor 130 can be determined based on the inductance of the first inductor 120 and the set resonant frequency, so that the harmonic suppression of the set resonant frequency can be accurately achieved. As an implementation, the inductance of the first inductor 120 can be 0.1-0.9nH. The capacitance of the first capacitor 130 can be 0.2-0.8pF.

[0056] It should be noted that in the circuit structure formed by the first inductor 120 and the first capacitor 130 being connected in parallel, since the capacitance of the first capacitor 130 is generally very small, the impedance of the first inductor 120 is dominant and the impedance of the first capacitor 130 can be ignored.

[0057] In one embodiment, Figure 3 As shown, the impedance matching circuit 100 further includes a first series resonant circuit 140 and a second series resonant circuit 150; the first series resonant circuit 140 includes a second inductor and a second capacitor connected in series, and the second series resonant circuit 150 includes a third inductor and a third capacitor connected in series.

[0058] The first end of the first series resonant circuit 140 is connected to the first end of the primary coil, and the second end of the first series resonant circuit 140 is grounded. The first end of the second series resonant circuit 150 is connected to the second end of the primary coil, and the second end of the second series resonant circuit 150 is grounded.

[0059] It should be noted that the first series resonant circuit 140 and the second series resonant circuit 150 can be symmetrically arranged based on the output end (the first end and the second end of the primary coil) of the differential power amplifier circuit 10, and can be used to suppress harmonics in the radio frequency signal output by the differential power amplifier circuit 10.

[0060] The positions of the second inductor and the second capacitor connected in series in the first series resonant circuit 140 can be interchanged. For example, the second inductor can be connected to ground through the second capacitor (eg Figure 3 As shown in FIG. 1 , the second capacitor may also be grounded through the second inductor. Similarly, the positions of the third inductor and the third capacitor in series in the second series resonant circuit 150 may also be interchanged, which will not be described in detail here.

[0061] In one embodiment, the resonant frequencies of the first series resonant circuit 140 and the second series resonant circuit 150 are set in the harmonic frequency band that needs to be suppressed, such as the second-order harmonic, the third-order harmonic, the fourth-order harmonic, etc. The first series resonant circuit 140 and the second series resonant circuit 150 are respectively connected to the first output terminal and the second output terminal of the differential power amplifier circuit 10. The first series resonant circuit 140 and the second series resonant circuit 150 are respectively set at different output terminals of the differential power amplifier circuit 10, which can more effectively achieve harmonic suppression.

[0062] The resonant frequency fn of the first series resonant circuit 140 and the second series resonant circuit 150 is given by the following formula: Wherein, fn represents the harmonic frequency to be suppressed, L1 represents the inductance of the second inductor or the third inductor, and C1 represents the capacitance of the second capacitor or the third capacitor.

[0063] The first series resonant circuit 140 and the second series resonant circuit 150 can be used to suppress any harmonics. The harmonic frequency to be suppressed can be determined according to actual needs, and the values ​​of the second inductor, the third inductor, the second capacitor, and the third capacitor can be set based on the harmonic frequency.

[0064] Exemplarily, the first series resonant circuit 140 and the second series resonant circuit 150 are used to achieve second-order harmonic suppression. The first capacitor 130 and the first inductor 120 are used to achieve third-order harmonic suppression or fourth-order harmonic suppression.

[0065] In one embodiment, if Figure 4 and Figure 5 As shown, the impedance matching circuit 100 further includes a matching capacitor 160; the other end of the secondary coil of the first balun 110 is grounded through the matching capacitor 160. The matching capacitor 160 can participate in the output impedance matching of the differential power amplifier circuit 10 together with the first balun 110 and the first inductor 120, thereby improving the working efficiency of the power amplifier.

[0066] In one embodiment, if Figure 5 As shown, the impedance matching circuit 100 further includes a capacitor C3; the capacitor C3 is connected to both ends of the primary coil of the first balun 110. The capacitor C3 can participate in the output impedance matching of the differential power amplifier circuit 10 together with the first balun 110, thereby improving the working efficiency of the power amplifier.

[0067] The impedance matching function of the first balun 110 and the first inductor 120 in the impedance matching circuit 100 is described below by using a specific example.

[0068] like Figure 6 As shown, the turns ratio of the secondary coil to the primary coil of the first balun 110 is set to 3:1, and the impedance conversion ratio is 3 2The RF signal frequency is in the high frequency band (2.3-2.7 GHz). The first inductor 120 is about 0.5 nH. The load impedance of the impedance matching circuit 100 is set to 50 Ω. Figure 6 The left part is a simulation diagram of the real part of the input impedance of the impedance matching circuit 100. Figure 6 The right part is a simulation diagram of the imaginary part of the input impedance of the impedance matching circuit 100 .

[0069] in, Figure 6 The line segment 11 in the figure represents the input impedance when the impedance matching circuit 100 only includes the first balun 110. It can be seen that in the high frequency band (2.3-2.7 GHz), the real part of the input impedance of the impedance matching circuit 100 fluctuates within the band up to 1Ω, and the imaginary part of the input impedance fluctuates within the band up to nearly 1Ω. Figure 6 The line segment 12 in the figure represents the input impedance of the impedance matching circuit 100 including both the first balun 110 and the first inductor 120. The real part of the input impedance has an in-band fluctuation of only 0.3Ω, and the imaginary part of the input impedance has an in-band fluctuation of almost 0. It can be seen that when the impedance matching circuit 100 includes both the first balun 110 and the first inductor 120, the in-band fluctuation of the input impedance is greatly optimized, and the input impedance is flatter.

[0070] The impedance matching circuit 100 described in the above embodiment includes a first balun 110 and a first inductor 120, and the impedance of the first inductor 120 is positively correlated with the impedance conversion ratio of the first balun 110, thereby compensating for the fluctuation of the input impedance of the impedance matching circuit 100 with the signal frequency. Wherein, assuming that the load impedance of the impedance matching circuit 100 remains unchanged, the greater the impedance conversion ratio of the first balun 110 to the higher frequency RF signal, the lower the input impedance of the impedance matching circuit 100. The higher the input impedance of the impedance matching circuit 100 can produce for the higher frequency RF signal, the higher the input impedance of the impedance matching circuit 100. Therefore, the first inductor 120 can compensate for the impedance fluctuation problem caused by the first balun 110 with the change of signal frequency, so that the impedance change amount under broadband is small and the input impedance is flatter, so that the impedance fluctuation of the differential power amplifier circuit 10 under broadband can be reduced.

[0071] Please refer to Figure 7 , Figure 7 A circuit diagram of an implementation of a radio frequency circuit provided in an embodiment of the present application.

[0072] like Figure 7 As shown, the radio frequency circuit 200 includes a differential power amplifier circuit 210 and an impedance matching circuit 220 , and the impedance matching circuit 220 is connected to the differential power amplifier circuit 210 .

[0073] The differential power amplifier circuit 210 is used to amplify the differential RF input signal to obtain a RF signal, and the impedance matching circuit 220 is used to perform impedance matching on the RF signal output by the differential power amplifier circuit 210. The differential power amplifier circuit 210 includes the differential power amplifier circuit 10 of the above embodiment, and the impedance matching circuit 220 includes the impedance matching circuit 100 of the above embodiment.

[0074] In one embodiment, if Figure 8 As shown, the differential power amplifier circuit 210 includes a first power amplifier unit 211 and a second power amplifier unit 212. The input end of the first power amplifier unit 211 is used to receive a first RF input signal, and the output end of the first power amplifier unit 211 serves as a first output end of the differential power amplifier circuit 210. The input end of the second power amplifier unit 212 is used to receive a second RF input signal, and the output end of the second power amplifier unit 212 serves as a second output end of the differential power amplifier circuit 210.

[0075] The first output end of the differential power amplifier circuit 210 is connected to the first end of the primary coil in the impedance matching circuit 220. The second output end of the differential power amplifier circuit 210 is connected to the second end of the primary coil in the impedance matching circuit 220. The first power amplifier unit 211 may include, for example, a first power amplifier PA1, and the second power amplifier unit 212 may include, for example, a second power amplifier PA2.

[0076] In one embodiment, the differential power amplifier circuit 210 is integrated on a chip, and the first balun and the first inductor in the impedance matching circuit 220 are disposed on a substrate.

[0077] In one embodiment, the radio frequency circuit further includes a front-stage power amplifier circuit, and the front-stage power amplifier circuit may include a single-ended power amplifier circuit or a differential power amplifier circuit.

[0078] For example, Fig. 9 As shown, when the front-stage power amplifier circuit includes a single-ended power amplifier circuit, the RF circuit also includes a third power amplifier unit 231 and a second balun 232. The third power amplifier unit 231 is connected to the input end of the first power amplifier unit 211 and the input end of the second power amplifier unit 212 through the second balun 232.

[0079] like Fig. 9 As shown, the second balun 232 includes a second primary coil and a second secondary coil coupled to each other; the first end of the second primary coil is connected to the third power amplifier unit 231, and the second end of the second primary coil is grounded through a second matching capacitor. The first end of the second secondary coil is connected to the input end of the first power amplifier unit 211, and the second end of the second secondary coil is connected to the input end of the second power amplifier unit 212.

[0080] Exemplarily, when the front-stage power amplifier circuit includes a differential power amplifier circuit, the radio frequency circuit also includes a front-stage differential power amplifier unit and an inter-stage matching unit; the front-stage differential power amplifier unit is connected to the differential power amplifier circuit 210 through the inter-stage matching unit.

[0081] Please refer to Fig.10 , Fig.10 A schematic diagram of the structure of the RF front-end module provided in an embodiment of the present application.

[0082] like Fig.10 As shown, the RF front-end module 300 includes a RF circuit 310 .

[0083] The RF circuit 310 may be the RF circuit 200 described in the above embodiment.

[0084] The RF front-end module 300 may further include a chip, and the differential power amplifier circuit in the RF circuit 310 may be integrated on the chip.

[0085] The RF front-end module 300 may further include a substrate, and the first balun and the first inductor of the impedance matching circuit in the RF circuit 310 may be disposed on the substrate.

[0086] This embodiment provides a radio frequency front-end module, which is a component that integrates two or more discrete devices such as a radio frequency switch, a low noise amplifier, a filter, a duplexer, a power amplifier, and a transformer into an independent module, thereby improving the integration and hardware performance of the radio frequency front-end module and miniaturizing its size. Specifically, the radio frequency front-end module can be applied to 4G and 5G communication devices such as smart phones, tablet computers, and smart watches.

[0087] With the development of information technology, 5G technology and 5G equipment have higher requirements for the performance of RF front-end modules. The technical solution provided in this application can provide an impedance matching circuit, a RF circuit and a RF front-end module, which can effectively reduce the impedance fluctuation of the differential power amplifier circuit under broadband, thereby meeting the needs of 5G technology and can be applied to 5G equipment.

[0088] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0089] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0090] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. An impedance matching circuit, characterized in that: The impedance matching circuit is connected to the differential power amplifier circuit and is used to perform impedance matching on the radio frequency signal output by the differential power amplifier circuit; The impedance matching circuit includes a first balun and a first inductor, wherein the first balun includes a primary coil and a secondary coil coupled with each other; The primary coil of the first balun is used to connect to the differential power amplifier circuit; One end of the secondary coil of the first balun is connected to the first inductor, and the other end is grounded; The impedance of the first inductor is positively correlated with the impedance conversion ratio of the first balun.

2. The impedance matching circuit according to claim 1, characterized in that: The relationship between the input impedance of the impedance matching circuit and the load impedance of the impedance matching circuit is: Z1 = (jwL + Z2) / N; Among them, Z1 represents the input impedance of the impedance matching circuit, j is an imaginary unit, w represents the angular frequency of the RF signal, L represents the inductance of the first inductor, jwL is the impedance of the first inductor to the RF signal, Z2 represents the load impedance of the impedance matching circuit, and N represents the impedance conversion ratio of the first balun.

3. The impedance matching circuit according to claim 1, characterized in that: The impedance matching circuit further includes a first capacitor, which is connected in parallel with the first inductor to resonate at a set resonant frequency.

4. The impedance matching circuit according to claim 3, characterized in that: The set resonant frequency is X times the operating frequency of the differential power amplifier circuit, where X is ≥ 2 and is an integer.

5. The impedance matching circuit according to claim 1, characterized in that: The impedance matching circuit further includes a first series resonant circuit and a second series resonant circuit; the first series resonant circuit includes a second inductor and a second capacitor connected in series, and the second series resonant circuit includes a third inductor and a third capacitor connected in series; The first end of the first series resonant circuit is connected to the first end of the primary coil, and the second end of the first series resonant circuit is grounded; the first end of the second series resonant circuit is connected to the second end of the primary coil, and the second end of the second series resonant circuit is grounded.

6. The impedance matching circuit according to claim 1, characterized in that: The impedance matching circuit also includes a matching capacitor; the other end of the secondary coil is grounded through the matching capacitor.

7. A radio frequency circuit, characterized in that: include: Differential power amplifier circuit; as well as The impedance matching circuit according to any one of claims 1 to 6, wherein the impedance matching circuit is connected to a differential power amplifier circuit.

8. The radio frequency circuit according to claim 7, characterized in that: The differential power amplifier circuit comprises a first power amplifier unit and a second power amplifier unit; The input end of the first power amplifier unit is used to receive a first radio frequency input signal, and the output end of the first power amplifier unit serves as a first output end of the differential power amplifier circuit; The input end of the second power amplifier unit is used to receive a second radio frequency input signal, and the output end of the second power amplifier unit serves as a second output end of the differential power amplifier circuit.

9. The radio frequency circuit according to claim 7, characterized in that: The differential power amplifier circuit is integrated on a chip, and the first balun and the first inductor in the impedance matching circuit are arranged on a substrate.

10. A radio frequency front-end module, characterized in that: Comprising a radio frequency circuit as described in any one of claims 7 to 9.

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