Radio frequency power amplifier

Abstract

The invention discloses a radio frequency power amplifier. A radio frequency power amplifier includes an input, at least two amplifier paths, an asymmetric power combiner circuit, and an output. The input end receives a radio frequency signal. Each amplifier path is coupled to an input. Each of the amplifier paths is to amplify a radio frequency signal to produce a corresponding amplified radio frequency signal. An asymmetric power combining circuit is coupled to the amplifier path to combine the amplified radio frequency signals generated by the amplifier path to generate a combined radio frequency signal. An output outputs the combined radio frequency signal. Each of the amplifier paths simultaneously produces a corresponding of the amplified radio frequency signal, and each of the amplifier paths has a reverse isolation superior to about 35 dB.

Description

Technical Field

[0001] The invention relates to a circuit design of wireless communication technology, and in particular to a radio frequency power amplifier. Background Art

[0002] In wireless communication technology, it is hoped that a radio frequency amplifier can be designed using an integrated circuit or chip with a limited volume, and the purpose is to allow the radio frequency amplifier to produce accurate or higher radio frequency output power. In this way, the signal transmission range of wireless communication technology can be further expanded. In the past, multiple radio frequency amplifier stage circuits with the same structure were often connected in parallel to increase the output power of the signal, but this circuit structure is difficult to improve the bandwidth and power added efficiency (PAE) of the final output signal, and will be accompanied by inevitable parasitic capacitance effects and signal loss. With the continuous demand for higher communication data transmission rates and low energy consumption and the adjustment from 3G communication protocols to 5G communication protocols, the signal bandwidth (for example, from 5MHz to 400MHz) and operating frequency (for example, from 1.9GHz to 39GHz) of the radio frequency amplifier are constantly increasing. In other words, broadband, high-power and high-efficiency radio frequency amplifiers are very important in wireless communication technology, so the circuit design of radio frequency amplifiers is very challenging. Summary of the invention

[0003] The radio frequency power amplifier of the present invention comprises an input end, at least two different amplifier paths, an asymmetric power combining circuit and an output end. The input end is used to receive a radio frequency signal. Each of the amplifier paths is coupled to the input end. Each of the amplifier paths is used to amplify the radio frequency signal to generate a corresponding amplified radio frequency signal. The asymmetric power combining circuit is coupled to the amplifier paths. The asymmetric power combining circuit is used to combine the amplified radio frequency signals generated by the amplifier paths to generate a combined radio frequency signal. The output end is used to output the combined radio frequency signal. Each of the amplifier paths simultaneously generates a corresponding amplified radio frequency signal, and the reverse isolation of each of the amplifier paths is better than about 35 dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 A module diagram of a radio frequency power amplifier according to a first embodiment of the present invention is shown.

[0005] Figure 2 A module diagram of a radio frequency power amplifier according to a second embodiment of the present invention is shown.

[0006] Figure 3 A module diagram of a radio frequency power amplifier according to a third embodiment of the present invention is shown.

[0007] Figure 4A module diagram of a radio frequency power amplifier according to a fourth embodiment of the present invention is shown.

[0008] Figure 5 A module diagram of a radio frequency power amplifier according to a fifth embodiment of the present invention is shown.

[0009] Figure 6 A circuit diagram of a radio frequency power amplifier according to a sixth embodiment of the present invention is shown.

[0010] Figures 7 to 12 Schematic diagram of various amplifier stage circuits in an amplifier path according to various embodiments of the present invention.

[0011] Fig.13 A circuit diagram of a radio frequency power amplifier according to a seventh embodiment of the present invention is shown.

[0012] Fig.14 A circuit diagram of a radio frequency power amplifier according to an eighth embodiment of the present invention is shown.

[0013] Fig.15 A circuit diagram of a radio frequency power amplifier according to a ninth embodiment of the present invention is shown.

[0014] Explanation of symbols:

[0015] 100-1~100-5、600、1300、1400、1500:RF power amplifier

[0016] 110-1 to 110-4, 1410-1 to 1410-2, 1510-1 to 1510-2: Amplifier path

[0017] 111-1~113-1、111-2、113-2、711、811、911、1011、1111、1211、1511-1~1512-1、1511-2~1512-2: amplifier circuit

[0018] 118-1~118-6、1518-1~1518-4: Matching circuit

[0019] 120, 1420: Asymmetric power combination circuit

[0020] 121~122、121-1~122-1、1421~1422: Impedance circuit

[0021] 130: Load circuit

[0022] 140: Detection circuit

[0023] 150: Control circuit

[0024] 1021: Resistor-capacitor series circuit

[0025] 1022, 1522-1, 1522-2: Resistor bias circuit

[0026] RFin: Input terminal

[0027] RFout: output terminal

[0028] RFS: Radio Frequency Signal

[0029] AS1, AS2: amplified RF signal

[0030] CRS: Combined Radio Frequency Signal

[0031] DS: Detection Signal

[0032] Z1, Z2: Impedance

[0033] C, Cpa1~Cpa2: capacitance

[0034] R, R11, R21, R31, R12, R22, R32, Rpa: resistance

[0035] L, L11, L21, L31, L12, L22, L32, Lpa: Inductance

[0036] FC, FC1~FC4: Filter circuit

[0037] VG, VG1~VG2, VD1, VD2, VD3, VDN: working voltage terminal

[0038] GND: reference voltage terminal

[0039] T11, T21, T31, T12, T22, T32, Tpa, Tpa1~Tpa6: transistors

[0040] PAin: Input terminal of amplifier circuit

[0041] PAout: output end of amplifier circuit

[0042] SAS1: First combined RF signal

[0043] SAS2: Second combined RF signal DETAILED DESCRIPTION

[0044] Figure 1The module diagram of the RF power amplifier 100-1 of the first embodiment of the present invention is shown. The RF power amplifier 100-1 includes an input terminal RFin, at least two different amplifier paths, an asymmetric power combining circuit 120, and an output terminal RFout. The input terminal RFin receives a RF signal. The RF power amplifier 100-1 processes and amplifies the RF signal RFS to output it to a load coupled to the output terminal RFout (e.g., a load circuit at the back end, or an antenna) through the output terminal RFout.

[0045] The radio frequency power amplifier of the embodiment of the present invention includes at least two different amplifier paths. Figure 1 The RF power amplifier 100-1 includes two different amplifier paths (e.g., a first amplifier path 110-1 and a second amplifier path 110-2). Each amplifier path 110-1, 110-2 is coupled to an input terminal RFin. Each amplifier path 110-1, 110-2 is used to amplify a RF signal RFS to generate corresponding amplified RF signals AS1, AS2. In this embodiment, the circuit structures / parameters (e.g., different transistor sizes, bias voltages, phases, signal gains, etc.) of the amplifier paths 110-1 and 110-2 are not exactly the same, so the amplifier paths 110-1 and 110-2 are asymmetric circuit structures. An asymmetric power combining circuit 120 is coupled to the amplifier paths 110-1 and 110-2. The asymmetric power combining circuit 120 is used to combine the amplified RF signals AS1, AS2 generated by the amplifier paths 110-1, 110-2 to create a combined RF signal CRS. The output terminal RFout is used to output the combined RF signal CRS. Each amplifier path 110-1, 110-2 simultaneously generates a corresponding amplified RF signal AS1, AS2. Since the output matching from the asymmetric power combining circuit 120 interacts with the circuits in the amplifier paths 110-1, 110-2, the combined output power Pout and PAE of the RF power amplifier are reduced. In this embodiment, the reverse isolation of each amplifier path 110-1, 110-2 is designed to be better than about 35dB to improve the combined output power Pout and PAE of the RF power amplifier. For example, the reverse isolation of each of the amplifier paths 110-1 and 110-2 is designed to be better than 35 to 40dB, depending on the operating frequency, etc. The "reverse isolation" described in this embodiment is the amplifier reverse transmission response measured from the output end of the amplifier path 110-1 or 110-2 to its input end.

[0046] Figure 2 A module diagram of a radio frequency power amplifier 100 - 2 according to a second embodiment of the present invention is shown. Figure 2It mainly presents the detailed module structure of the load circuit 130 and the asymmetric power combination circuit 120 in the RF power amplifier 100 - 2 . Figure 2 The RF power amplifier 100 - 2 further includes a load circuit 130 coupled to the output terminal RFout. The load circuit 130 may be a back-end circuit structure, an antenna, or a combination of the two.

[0047] Figure 2 The asymmetric power combination circuit 120 of the RF power amplifier 100-2 includes impedance circuits 121 and 122. The impedance circuit 121 is coupled between the output terminal RFout and the amplifier path 110-1. The impedance circuit 122 is coupled between the output terminal RFout and the amplifier path 110-2. The circuit structures / parameters of the impedance circuits 121 and 122 of the present embodiment are not completely the same, so the impedance circuits 121 and 122 are asymmetric circuit structures. With the output terminal RFout as a reference, the impedance circuit 121 has an impedance Z1 and the impedance circuit 122 has an impedance Z2. In other words, when looking from the output terminal RFout to the impedance circuits 121 and 122, the impedance circuits 121 and 122 respectively have impedances Z1 and Z2.

[0048] The present embodiment is designed so that the impedances Z1 and Z2 are substantially complex conjugate matched. The present embodiment designs the impedance circuits 121 and 122 so that the impedance difference between the impedances Z1 and Z2 is within plus or minus 25%. Furthermore, the equivalent impedance formed by the impedances Z1 and Z2 is approximately equal to the impedance of the load circuit 130. In this way, the signal bandwidth of the RF power amplifier will be increased. For example, the impedance of the load circuit 130 may be designed to be 50 ohms (Ω), and the impedances Z1 and Z2 are designed toward 100 ohms. Since the impedances Z1 and Z2 are connected in parallel, the impedance value formed by the impedances Z1 and Z2 after being connected in parallel is approximately 50 ohms.

[0049] Figure 3 A module diagram of a radio frequency power amplifier 100-3 according to a third embodiment of the present invention is shown. In this embodiment, the impedance Z1 corresponding to the impedance circuit 121 and the impedance Z2 corresponding to the impedance circuit 122 are variable. In this embodiment, circuit elements (e.g., variable capacitors, variable resistors, variable inductors, etc.) that can be controlled to adjust their own values ​​can be set in the internal structures of the impedance circuits 121 and 122, and these circuit elements can be controlled by the control circuit 150.

[0050] Figure 3The RF power amplifier 100-3 also includes a detection circuit 140 and a control circuit 150. The detection circuit 140 is used to detect the electrical characteristics of the RF signal RFS or the combined RF signal CRS and generate a detection signal DS. The aforementioned electrical characteristics may be the signal frequency or signal power of the signal, etc. The control circuit 150 is coupled to the detection circuit 140. The control circuit 150 controls at least part of the circuit elements in the impedance circuits 121 and 122 according to the detection signal DS to adjust the impedance Z1 and the impedance Z2, thereby adaptively adjusting the characteristics of the RF power amplifier. The characteristics of the aforementioned RF power amplifier are, for example, gain (Gain), 1dB compression point (OP1dB), maximum power added efficiency (Max.PAE), and / or output power in saturation state (Pout, SAT)... etc.

[0051] For example, the detection circuit 140 is used to detect the signal frequency of the RF signal RFS or the combined RF signal CRS, and generates a detection signal DS related to the signal frequency through a look-up table. The control circuit 150 controls the variable circuit elements in the impedance circuits 121 and 122 according to the detection signal DS to adjust the impedance Z1 and the impedance Z2, so that the characteristics of the power amplifier can still be maintained within a reasonable range when the signal frequency changes, so as to further increase the signal bandwidth of the RF power amplifier. Figure 3 The detection circuit 140 and the control circuit 150 can be applied to many embodiments of the present invention. For the convenience of explaining other contents, the detection circuit 140 and the control circuit 150 are not additionally illustrated in the corresponding figures of other embodiments.

[0052] Figure 4 A module diagram of a radio frequency power amplifier 100 - 4 according to a fourth embodiment of the present invention is shown. Figure 4Each amplifier path 110-1, 110-2 of the RF power amplifier 100-4 may include a plurality of amplifier stage circuits connected in series. In order to make the reverse isolation of each amplifier path 110-1, 110-2 better than about 35dB (for example, better than 35 to 40dB, depending on the operating frequency, etc.), the number of amplifier stage circuits connected in series in each amplifier path 110-1, 110-2 may be designed to be greater than or equal to 3. For example, the amplifier path 110-1 includes three amplifier stage circuits 111-1 to 113-1, and the amplifier path 110-2 includes three amplifier stage circuits 111-2 to 113-2. Compared to the embodiment in which the amplifier paths 110-1 and 110-2 only include two amplifier stage circuits, the fourth embodiment of the present invention has a larger number of amplifier stage circuits and a larger number of corresponding matching circuits. Generally speaking, it is considered that it is easier to interact with the output matching from the asymmetric power combining circuit 120, thereby reducing the output power (Pout) and PAE of the RF power amplifier 100-1. However, because the order of the amplifier stage circuits in the fourth embodiment of the present invention is increased, the reverse isolation of the amplifier paths 110-1 and 110-2 is improved, thereby reducing the interaction between the matching circuits in the amplifier paths 110-1 and 110-2 and the output matching of the asymmetric power combining circuit 120, thereby actually improving the output power (Pout) and PAE of the RF power amplifier 100-1.

[0053] In detail, in the present embodiment, when designing the RF power amplifier 100-4, two amplifier paths 110-1 and 110-2 are connected in parallel, and the amplifier paths 110-1 and 110-2 each include three amplifier stage circuits 111-1 to 113-1, 111-2 to 113-2, and the amplifier stage circuits 111-1 to 113-1, 111-2 to 113-2 in the amplifier paths 110-1 and 110-2 can each have different types of amplifier types. The aforementioned amplifier types are, for example, common source amplifiers, common emitter amplifiers, cascode amplifiers, multi-stacked-transistors amplifiers, various types of cascade amplifiers, two-stack amplifiers, etc.

[0054] This embodiment can also be designed so that the amplifier circuits with the same order in the amplifier paths 110-1 and 110-2 (e.g., amplifier circuits 111-1 and 111-2, 112-1 and 112-2, 113-1 and 113-2) are of the same type (e.g., the amplifier circuits in the amplifier paths are all common source amplifiers or common emitter amplifiers), and the amplifier circuits with the same order in the amplifier paths are each provided with different transistor sizes. In this way, the amplifier paths 110-1 and 110-2 in the RF power amplifier 100-4 can be designed to be an asymmetric circuit structure.

[0055] Figure 5 A module diagram of a radio frequency power amplifier 100 - 5 according to a fifth embodiment of the present invention is shown. Figure 5 The RF power amplifier 100-5 also includes at least one impedance matching circuit, for example Figure 5 Matching circuits 118-1 to 118-6. Matching circuits 118-2 to 118-3, 118-5 and 118-6 are coupled between amplifier stage circuits 111 to 113-1, 111-2 to 113-2 connected in series in amplifier paths 110-1 and 110-2. Matching circuit 118-1 is coupled between amplifier stage circuit 111-1 coupled to input terminal RFin and input terminal RFin in amplifier path 110-1. Matching circuit 118-4 is coupled between amplifier stage circuit 111-2 coupled to input terminal RFin and input terminal RFin in amplifier path 110-2. The user of this embodiment appropriately adjusts the signal gain, bandwidth, output impedance and power consumption of amplifier paths 110-1 and 110-2 by designing matching circuits 118-1 to 118-6.

[0056] Figure 6 FIG. 6 is a circuit diagram of a radio frequency power amplifier 600 according to a sixth embodiment of the present invention. Figure 5 A detailed circuit diagram of the RF power amplifier 100-5. Figure 6The amplifier circuits 111-1 to 113-1, 111-2 to 113-2 connected in series in the amplifier paths 110-1 to 110-2 are all common source amplifiers (or common emitter amplifiers), but they can also be cascade amplifiers. Compared with common source amplifiers, the cascade amplifiers will improve reverse isolation and have better reverse isolation characteristics. In detail, taking the amplifier circuit 111-1 as an example, the amplifier circuit 111-1 is used to receive the working voltage VD1 and includes a transistor T11, a resistor R11 and an inductor L11 that constitute a common source amplifier. The control end of the transistor T11 is used to input a radio frequency signal, the first end (drain end) of the transistor T11 is used to receive the working voltage VD1 and output the amplified radio frequency signal, and the second end (source end) of the transistor T11 is used to receive a reference voltage. The amplifier stage circuit 111-1 further includes other circuit elements (e.g., inductor L) to adaptively adjust the signal gain, bandwidth, output impedance, power consumption, etc. of the amplifier paths 110-1 and 110-2. Similar to the circuit structure of the amplifier stage circuit 111-1, the amplifier stage circuits 112-1, 113-1, 111-2, 112-2, and 113-2 are respectively used to receive the working voltages VD2, VD3, VD1, VD2, and VD3 and include transistors T21, T31, T12, T22, and T32, resistors R21, R31, R12, R22, and R32, and inductors L21, L31, L12, L22, and L32 that form a common source amplifier. The amplifier stage circuit 112-1 further includes other circuit elements, such as a filter circuit FC12.

[0057] It is particularly noted that the common source amplifiers or common emitter amplifiers with the same order in the amplifier paths 110-1 and 110-2 (e.g., the common source amplifiers in the amplifier stage circuits 111-1 and 111-2, 112-1 and 112-2, 113-1 and 113-2) may have at least one order with different transistor sizes. The common source amplifiers or common emitter amplifiers with the same order in the amplifier paths 110-1 and 110-2 may also have different transistor sizes. For example, in this embodiment, the size of the transistor T11 in the common source amplifier in the amplifier stage circuit 111-1 is 2×25 micrometers (μm), and the size of the transistor T12 in the common source amplifier in the amplifier stage circuit 111-2 is 2×15 μm; the size of the transistor T21 is 2×50 μm, and the size of the transistor T22 is 2×25 μm; the size of the transistor T31 is 4×75 μm, and the size of the transistor T32 is 4×50 μm. Therefore, the circuit structures / parameters of the amplifier paths 110 - 1 and 110 - 2 are different from each other, and the RF power amplifier 600 has an asymmetric circuit structure.

[0058] The matching circuits 118-1 to 118-6 can be implemented by resistors R, capacitors C, inductors L, filter circuits FC, or any combination of the above four. Although the matching circuits 118-1 to 118-6 all have resistors, capacitors, and inductors marked as R, C, and L, respectively, the values ​​of each resistor R, each capacitor C, and each inductor L are not necessarily the same, but can be adjusted by the user of the present embodiment according to their needs. The filter circuits in the various embodiments of the present invention (e.g., filter circuits FC, FC12) can be resistors or circuits composed of inductor-capacitor (LC) elements or resistor-inductor-capacitor (RLC) elements, and the circuit structure of each filter circuit is not necessarily the same. The user of the present embodiment can adjust the circuit structure of each filter circuit according to their needs.

[0059] The asymmetric power combination circuit 120 includes impedance circuits 121 and 122 . Figure 6 The circuit structures of the impedance circuits 121 and 122 are different. The impedance circuit 121 is composed of a capacitor C and two filter circuits FC1 and FC2. The impedance circuit 122 is composed of two capacitors C and two filter circuits FC3 and FC4.

[0060] Table 1 presents some simulation characteristics of the RF power amplifier 600 from 26 to 30 GHz. Since the number of amplifier stage circuits connected in series in each amplifier path 110-1, 110-2 of the RF power amplifier 600 is designed to be greater than or equal to 3, the reverse isolation of each amplifier path 110-1, 110-2 can be better than about 35 dB, thereby providing the RF power amplifier 600 with better gain (Gain), 1dB compression point (OP1dB), maximum power added efficiency (Max.PAE), and output power in saturation state (Pout, SAT) at multiple frequencies, so it can also meet broadband requirements.

[0061] Frequency (GHz) 26 28 30 Gain(dB) 25.5 26.6 25.8 OP1dB(dBm) 17.2 12.1 13.6 Max.PAE(%) 28.1 16.3 27.9 Pout,SAT(dBm) 21.7 19.2 21

[0062] Table 1

[0063] The sixth embodiment Figure 6The amplifier stage circuits 111-1, 112-1, 113-1, 111-2, 112-2 and 113-2 are used to receive working voltages VD1, VD2, VD3, VD1, VD2 and VD3 respectively. The corresponding embodiment of Table 1 is an example in which VD1, VD2 and VD3 are the same. In other embodiments, VD1, VD2 and VD3 may also be different, for example, VD3 is greater than VD2 and VD1. In other words, the working voltage VD3 of the last-stage amplifier stage circuit 113-1, 113-2 in the amplifier path 110-1, 110-2 may be greater than the working voltages VD1, VD2 of the other-stage amplifier stage circuits 111-1~111-2, 112-1~112-2. Please refer to Table 2, which shows some characteristics of the RF power amplifier 600 when VD3 is larger than VD2 and VD1, for example, when VD3 is 1 Volt larger than VD2 and VD1.

[0064] Frequency (GHz) 25.5 28 30 Gain(dB) 28.1 26.6 31 OP1dB(dBm) 22.3 16.1 17.2 Max.PAE(%) 38.6 21.9 31 Pout,SAT(dBm) 22.5 19.9 21.2

[0065] Table 2

[0066] Compared with the embodiment corresponding to Table 1 (VD1, VD2 and VD3 are the same), the embodiment corresponding to Table 2 (VD3 is larger than VD2 and VD1) can provide the RF power amplifier 600 with better gain (Gain), 1dB compression point (OP1dB), maximum power added efficiency (Max.PAE), and output power in saturation state (Pout, SAT) at multiple frequencies, so it can better meet the requirements of broadband. Table 3 is the measurement results of the embodiments corresponding to Table 1 and Table 2. In Table 3, the embodiment corresponding to Table 2 has better performance than the embodiment corresponding to Table 1.

[0067]

[0068]

[0069] Table 3

[0070] It is particularly noted that, since common source amplifiers and common emitter amplifiers have better reverse isolation characteristics, the sixth embodiment takes the amplifier stage circuits as common source amplifiers as an example, so as to better achieve the technical feature that the reverse isolation of each amplifier path is better than about 35dB. However, in other embodiments, in addition to being realized by common source amplifiers or common emitter amplifiers, Figure 6 In addition to the amplifier circuits 111-1 to 113-1 and 111-2 to 113-2, different types of cascade amplifiers or cascade amplifiers can also be used to implement the circuits. Figure 6 The amplifier stage circuits 111 - 1 ˜ 113 - 1 and 111 - 2 ˜ 113 - 2 can also achieve the technical feature that the reverse isolation of each amplifier path is better than about 35 dB. Figures 7 to 12 This is a circuit diagram of each amplifier stage circuit located in the amplifier path in accordance with many embodiments of the present invention. Figures 7 to 12 The mid-amplifier circuit is selectively applied to Figures 1 to 6 Each amplifier stage circuit in the RF power amplifier. For example, Figure 6 Each amplifier stage circuit in the RF power amplifier 600 may be a common source amplifier (corresponding to Figure 6 and Figure 7 ), common emitter amplifier, cascode amplifier (corresponding to Figure 8 ), cascade amplifier (corresponding to Fig. 9 ), double stack amplifier (corresponding to Fig.10 ), a common-source amplifier in cascade with a common-gate amplifier, corresponding to Fig.11 ) or a multi-stacked-transistors amplifier (e.g., a three-stacked-transistors amplifier, etc., corresponding to Fig.12 ), or a combination of the above amplifiers. In addition, since the last amplifier stage circuit in the multiple amplifier stage circuits connected in series provides a larger part of the reverse isolation characteristics, Figure 6 The amplifier stages 113-1 and 113-2 in the amplifier paths 110-1 and 110-2 coupled to the asymmetrical power combination circuit 120 (i.e., the last amplifier stage circuits in the plurality of amplifier stage circuits connected in series corresponding to different amplifier paths) can be cascade amplifiers, which can improve reverse isolation and have better reverse isolation characteristics compared to common source amplifiers (or common emitter amplifiers). Therefore, in other embodiments, the last amplifier stage circuit can also be a common source amplifier (corresponding to Figure 6 and Figure 7 ) is adjusted to a cascode amplifier (corresponding to Figure 8 ), cascade amplifier (corresponding to Fig. 9 ), double stack amplifier (corresponding to Fig.10 ), a cascaded amplifier connected in series from a common source amplifier to a common gate amplifier (corresponding to Fig.11 ) or a multi-stacked-transistors amplifier (e.g., a three-stacked-transistors amplifier, etc., corresponding to Fig.12 ), and can also achieve a technical feature of reverse isolation of better than about 35dB for each amplifier path.

[0071] Detailed description here Figures 7 to 12 Each amplifier stage circuit in the. Figures 7 to 12 The transistors Tpa, Tpa1 and Tpa2 can be implemented by metal oxide semi-conductor field effect transistors (MOSFET), and the first end, the second end and the control end of the transistors Tpa, Tpa1 and Tpa2 can be the drain end, the source end and the gate end respectively. In other embodiments consistent with the present invention, Figures 7 to 12 The transistors Tpa, Tpa1 and Tpa2 can also be implemented by bipolar junction transistors (BJT), and the first end, the second end and the control end of the transistors Tpa1 and Tpa2 can also be the collector end, the emitter end and the base end respectively.

[0072] See also Figure 7 , Figure 7 The amplifier stage circuit 711 is a common source amplifier. The amplifier stage circuit 711 includes an input terminal PAin, a transistor Tpa, an inductor Lpa and an output terminal PAout. The control terminal (gate terminal) of the transistor Tpa is coupled to the input terminal PAin. The second terminal (source terminal) of the transistor Tpa is coupled to the reference voltage terminal GND, and the first terminal (drain terminal) of the transistor Tpa is coupled to the output terminal PAout and one end of the inductor Lpa. The other end of the inductor Lpa is coupled to the working voltage terminal VDN. The amplifier stage circuit 711 may selectively include a resistor Rpa, which is coupled between the input terminal PAin and the working voltage terminal VG. The amplifier stage circuit 711 may also be replaced by a common emitter amplifier, in which the first terminal, the second terminal and the control terminal of the transistor Tpa are the collector, the emitter and the base, respectively.

[0073] See also Figure 8 , Figure 8 The amplifier stage circuit 811 is a stacked amplifier in each embodiment of the present invention. The amplifier stage circuit 811 includes an input terminal PAin, transistors Tpa1, Tpa2 and an output terminal PAout. The control terminal (gate terminal) of transistor Tpa1 is coupled to the input terminal PAin, the second terminal (source terminal) of transistor Tpa1 is coupled to the reference voltage terminal GND, and the first terminal (drain terminal) of transistor Tpa1 is coupled to the second terminal (source terminal) of transistor Tpa2. The control terminal of transistor Tpa2 is coupled to the working voltage terminal VDN, and the first terminal (drain terminal) of transistor Tpa2 is coupled to the output terminal PAout. It is particularly noted that, compared to Figure 7 The common source amplifier, Figure 8 The cascaded amplifiers in the embodiment have better reverse isolation characteristics, and thus can better achieve the technical characteristic of better than about 35dB reverse isolation for each amplifier path (depending on the operating frequency, etc.).

[0074] See also Fig. 9 , Fig. 9The amplification stage circuit 911 is a cascaded amplifier. The amplification stage circuit 911 includes an input terminal PAin, transistors Tpa1, Tpa2, and an output terminal PAout. The control terminal (gate terminal) of transistor Tpa1 is coupled to the input terminal PAin, the second terminal (source terminal) of transistor Tpa1 is coupled to the reference voltage terminal GND, and the first terminal (drain terminal) of transistor Tpa1 is coupled to the control terminal (gate terminal) of transistor Tpa2. The second terminal (source terminal) of transistor Tpa2 is coupled to the reference voltage terminal GND, and the first terminal (drain terminal) of transistor Tpa2 is coupled to the output terminal PAout. It should be specifically noted that, compared with Figure 7 the common-source amplifier, Fig. 9 the cascaded amplifier has better reverse isolation characteristics, so that the technical feature that the reverse isolation of each amplifier path is better than about 35 dB (depending on the operating frequency, etc.) can be better achieved.

[0075] See Fig.10 , Fig.10 The amplification stage circuit 1011 is a two-stack amplifier in various embodiments of the present invention. Fig.10 There are two mutually stacked transistors in the amplification stage circuit 1011, which is called a two-stack amplifier. Fig.10 The amplification stage circuit 1011 includes an input terminal PAin, transistors Tpa1 and Tpa2, a capacitor Cpa1, a resistor biasing circuit 1022, and an output terminal PAout. The control terminal (gate terminal) of transistor Tpa1 is coupled to the input terminal PAin, and the second terminal (source terminal) of transistor Tpa1 is coupled to the reference voltage terminal GND. The first terminal (drain terminal) of transistor Tpa1 is coupled to the second terminal (source terminal) of transistor Tpa2. The first terminal (drain terminal) of transistor Tpa2 is coupled to the output terminal PAout. The control terminal (gate terminal) of transistor Tpa2 is coupled to the reference voltage terminal GND through the capacitor Cpa1. The control terminal of transistor Tpa2 is also coupled to the operating voltage terminal VDN through the resistor biasing circuit 1022. The amplification stage circuit 1011 may selectively include a capacitor Cpa2 and a resistor-capacitor series circuit 1021. The control terminal of transistor Tpa1 is coupled to the input terminal PAin through the capacitor Cpa2, and the control terminal of transistor Tpa1 is also coupled to the reference voltage terminal GND through the resistor-capacitor series circuit 1021. It should be specifically noted that, compared with Figure 8 the stacked amplifier, Fig.10 the two-stack amplifier has better reverse isolation characteristics, so that the technical feature that the reverse isolation of each amplifier path is better than about 35 dB can be better achieved.

[0076] See Fig.11 , Fig.11The amplifier stage circuit 1111 is another effect of a cascaded amplifier in which a common-source amplifier is serially connected to a common-gate amplifier in each embodiment of the present invention. Fig.11 The amplifier stage circuit 1111 has two transistors, called a cascade amplifier, which is a common-source amplifier connected in series to a common-gate amplifier. Fig.11 The amplifier stage circuit 1111 includes an input terminal PAin, a transistor Tpa1 and a transistor Tpa2, a capacitor Cpa1, a filter circuit FC1 and an output terminal PAout. The control terminal (gate terminal) of the transistor Tpa1 is coupled to the input terminal PAin, and the second terminal (source terminal) of the transistor Tpa1 is coupled to the reference voltage terminal GND. The first terminal (drain terminal) of the transistor Tpa1 is coupled to the second terminal (source terminal) of the transistor Tpa2. The control terminal (gate terminal) of the transistor Tpa2 is coupled to the reference voltage terminal GND through the capacitor Cpa1. The filter circuit FC1 is coupled between the control terminal of the transistor Tpa2 and the second terminal (source terminal) of the transistor Tpa2. The first terminal (drain terminal) of the transistor Tpa2 serves as the signal output terminal (i.e., the output terminal PAout) of the amplifier stage circuit 1111. The filter circuit FC1 may include a resistor, or may include an inductor-capacitor (LC) circuit or a resistor-inductor-capacitor (RLC) circuit. It is particularly noted that, compared to Fig.10 Dual stack amplifiers, Fig.11 The stacked amplifier also has good reverse isolation characteristics, so it can better achieve the technical feature of reverse isolation of each amplifier path being better than about 35dB.

[0077] See also Fig.12 , Fig.12 The amplifier stage circuit 1211 is a multi-stack transistor amplifier in each embodiment of the present invention. The multi-stack transistor amplifier can be a three-stack transistor amplifier (corresponding to Fig.12 ), a four-stacked transistor amplifier, etc. That is, the multi-stacked transistor amplifier may be an N-stacked transistor amplifier having N stacked transistors, and N>2. Fig.12 The amplifier stage circuit 1211 includes three stacked transistors, which is also called a three-stack amplifier. Fig.12 The amplifier circuit 1211 is mainly based on Fig.11 The amplifier stage circuit 1111 also adds a circuit structure of a stacked transistor (eg, transistor Tpa3). The amplifier stage circuit 1211 includes three transistors Tpa1, Tpa2, and Tpa3. In detail, Fig.12 Compared with the amplifier stage circuit 1211 Fig.10The amplifier stage circuit 1011 further includes a transistor Tpa3, a capacitor Cpa2 and a filter circuit FC2. The second end (source end) of the transistor Tpa3 is coupled to the first end (drain end) of the transistor Tpa2. The control end (gate end) of the transistor Tpa3 is coupled to the reference voltage end GND through the capacitor Cpa2. The filter circuit FC2 is coupled between the control end of the transistor Tpa3 and the second end (source end) of the transistor Tpa3. The first end (drain end) of the transistor Tpa3 serves as the signal output end (i.e., the output end PAout) of the amplifier stage circuit 1211. It is particularly noted that, compared to Fig.11 The stacked amplifier, Fig.12 The multi-stacked transistor amplifier has better reverse isolation characteristics, so the technical feature of better than about 35dB reverse isolation for each amplifier path can be better and significantly achieved with only a single three-stacked amplifier.

[0078] The user of this embodiment can Figures 7 to 12 The mid-amplifier circuit is selectively applied to Figures 1 to 6 Furthermore, if the types of the amplifier stages with the same order in each amplifier path are the same, this embodiment is designed so that the amplifier stages with the same order in each amplifier path have different transistor sizes.

[0079] Fig.13 A circuit diagram of a radio frequency power amplifier 1300 according to a seventh embodiment of the present invention is shown. The radio frequency power amplifier according to various embodiments of the present invention may include two or more amplifier paths and utilize an asymmetric power combining circuit 120 to combine the amplified radio frequency signals. For example, Fig.13The RF power amplifier 1300 includes four amplifier paths 110-1 to 110-4 and an asymmetric power combining circuit 120. The circuit structures / parameters of the amplifier paths 110-1 to 110-4 are not completely the same, so as to form an asymmetric circuit structure. The asymmetric power combining circuit 120 includes sub-power combining circuits 121-1 and 121-2. The sub-power combining circuit 121-1 is used to combine the two amplified RF signals generated by the amplifier paths 110-1 and 110-2 to generate a first combined RF signal SAS1. The sub-power combining circuit 121-2 is used to combine the two amplified RF signals generated by the amplifier path 110-3 and the amplifier path 110-4 to generate a second combined RF signal SAS2. The first and second combined RF signals are superimposed to form a combined RF signal CRS output through the output terminal RFout to provide a higher output power. In addition, the impedance of the amplifier paths 110-1 to 110-4 and the sub-power combination circuits 121-1 and 121-2 are designed in this embodiment to meet the output impedance requirements of this embodiment. Figures 2 to 6 , further including a load circuit 130 coupled to the output terminal RFout. When the output terminal RFout is used as a reference, the impedances Z1 and Z2 of the sub-power combination circuits 121-1 and 121-2 are approximately 100 ohms respectively. Therefore, the impedances Z1 and Z2 of the sub-power combination circuits 121-1 and 121-2 after being connected in series are approximately equal to the impedance (50 ohms) of the load circuit 130.

[0080] In some embodiments, Fig.10 Dual stack amplifiers, Fig.11 The stacked amplifier and Fig.12 The multi-stacked transistor amplifier has sufficient reverse isolation characteristics. Therefore, under proper design, when the amplifier stage circuit 1011, 1111 or 1211 is used as the last amplifier stage circuit in a plurality of amplifier stage circuits connected in series in an amplifier path, or even as a single first-order amplifier stage circuit in an amplifier path, the reverse isolation of each amplifier path can be better than about 35 dB, without the need to set more than or equal to three amplifier stage circuits connected in series in each amplifier path.

[0081] Fig.14 FIG. 1 is a circuit diagram of a radio frequency power amplifier 1400 according to an eighth embodiment of the present invention. Figure 1 and Figure 2 A detailed circuit diagram of one of the RF power amplifiers 100 - 1 and 100 - 2 . The RF power amplifier 1400 mainly includes an input terminal RFin, amplifier paths 1410 - 1 and 1410 - 2 , an asymmetric power combining circuit 1420 , and an output terminal RFout. Fig.14 Each of the amplifier paths 1410-1 and 1410-2 has a first-order amplifier stage circuit, and the circuit structure of this amplifier stage circuit is the same as that of Fig.12 the amplifier stage circuit 1211 (the aforementioned triple-stack amplifier). It should be noted that the circuit structures / parameters of the amplifier paths 1410-1 and 1410-2 are not exactly the same. The size of the transistor Tpa1 in the amplifier stage circuit of the amplifier path 1410-1 is different from the size of the transistor Tpa4 in the amplifier stage circuit of the amplifier path 1410-2. The size of the transistor Tpa2 in the amplifier stage circuit of the amplifier path 1410-1 is different from the size of the transistor Tpa5 in the amplifier stage circuit of the amplifier path 1410-2. The size of the transistor Tpa3 in the amplifier stage circuit of the amplifier path 1410-1 is different from the size of the transistor Tpa6 in the amplifier stage circuit of the amplifier path 1410-2. The asymmetric power combining circuit 1420 includes impedance circuits 1421 and 1422. Fig.14 For the detailed circuit structure and operation of the RF power amplifier 1400, please refer to the foregoing Figure 1 , Figure 2 , Fig.12 and the corresponding descriptions of the foregoing embodiments.

[0082] Fig.15 FIG. shows a circuit schematic diagram of the RF power amplifier 1500 according to the ninth embodiment of the present invention. The RF power amplifier 1500 is one of the detailed circuit diagrams that conforms to Figure 1 and Figure 2 the RF power amplifiers 100-1 and 100-2. The RF power amplifier 1500 includes an input terminal RFin, amplifier paths 1510-1 and 1510-2, an asymmetric power combining circuit 1520, and an output terminal RFout. Each of the amplifier paths 1510-1 and 1510-2 has two-order amplifier stage circuits 1511-1 to 1511-2 and 1512-1 to 1512-2. The amplifier paths 1510-1 and 1510-2 further include matching circuits 1518-1 to 1518-4. The matching circuit 1518-1 is coupled between the amplifier stage circuit 1511-1 in the amplifier path 1510-1 and the input terminal RFin. The matching circuit 1518-2 is coupled between the amplifier stage circuits 1511-1 and 1511-2. The matching circuit 1518-3 is coupled between the amplifier stage circuit 1512-1 in the amplifier path 1510-2 and the input terminal RFin. The matching circuit 1518-4 is coupled between the amplifier stage circuits 1512-1 and 1512-2.

[0083] The first-order amplifier stage circuits 1511-1 and 1512-1 in the amplifier paths 1510-1 and 1510-2 are both common-source amplifiers (similar to Figure 7The circuit structure of the common source amplifier 711 is similar to that of the common source amplifier 711, but the circuit structures / parameters (especially the size of the transistors) of the two are slightly different. The first-stage amplifier circuits 1511-1 and 1512-1 in the amplifier paths 1510-1 and 1510-2 are both common source amplifiers. The amplifier circuit 1511-1 includes a transistor T11 that constitutes a common source amplifier. The amplifier circuit 1511-1 may also selectively include a resistor R11, an inductor L11, and other components not shown. Fig.15 The inductor L11 is coupled to the working voltage terminal VD1. The resistor R11 is coupled to the working voltage terminal VG1. The amplifier stage circuit 1512-1 includes a transistor T21 that constitutes a common source amplifier. The amplifier stage circuit 1512-1 may also selectively include a resistor R21, an inductor L21, and other components not shown in FIG. Fig.15 The inductor L21 is coupled to the working voltage terminal VD1. The resistor R21 is coupled to the working voltage terminal VG1.

[0084] The second-stage amplifier circuits 1511-2 and 1512-2 in the amplifier paths 1510-1 and 1510-2 are both double-stack amplifiers (similar to Fig.10 The circuit structure of the double stacked series amplifier 1011) is similar to that of the double stacked series amplifier 1011, but the circuit structures / parameters (especially the size of the transistors) of the two are slightly different. Taking the amplifier stage circuit 1511-2 as an example, the amplifier stage circuit 1511-2 mainly includes transistors Tpa1, Tpa2, capacitor Cpa1 and a resistor bias circuit 1522-1 connected in series with each other. The amplifier stage circuit 1511-2 may also selectively include a capacitor Cpa2 and a resistor bias circuit 1522-2. The control end of the transistor Tpa1 is coupled to the input end PAin through the capacitor Cpa2. The control end of the transistor Tpa1 is also coupled to the working voltage end VG1 through the resistor bias circuit 1522-2. The control end of the transistor Tpa2 is coupled to the reference voltage end GND through the capacitor Cpa1. The control end of the transistor Tpa2 is also coupled to the working voltage end VG3 through the resistor bias circuit 1522-1. The circuit structure of the amplifier stage circuit 1511 - 2 is similar to that of the amplifier stage circuit 1512 - 2 , but the size of the transistor Tpa1 is different from that of the transistor Tpa3 , and the size of the transistor Tpa2 is different from that of the transistor Tpa4 .

[0085] Table 4 shows some simulation characteristics of the RF power amplifier 1500. Table 5 shows some simulation characteristics when the dual stacked amplifiers of the second-stage amplifier circuits 1511-2 and 1512-2 of the RF power amplifier 1500 are replaced with common source amplifiers. In other words, the first-stage amplifier circuit and the second-stage amplifier circuit of the RF power amplifier corresponding to Table 4 are both common source amplifiers. It can be seen from Tables 3 and 4 that although the RF power amplifier 1500 only has two-stage amplifier circuits, since its last stage is a dual stacked amplifier, it can provide sufficient isolation and provide better small signal gain (Small Signal Gain), 1dB compression point (OP1dB), output power 1dB compression point power added efficiency (PAE@P1dB), and maximum power added efficiency (Max.PAE) at multiple frequencies, so it can better meet the needs of broadband.

[0086] Frequency (GHz) 24 28 30 Gain(dB) 17.8 20.6 20.4 OP1dB(dBm) 26.4 27.3 26.6 Max.PAE(%) 28.5 36.2 30.5 Pout,SAT(dBm) 34 42.4 44

[0087] Table 4

[0088] Frequency (GHz) 24 28 30 Gain(dB) 14.5 15.8 14.4 OP1dB(dBm) 18.7 26 26.3 Max.PAE(%) 24.4 25 27.3 Pout,SAT(dBm) 22.7 32.3 29.8

[0089] Table 5

[0090] In summary, the RF power amplifier provided by the embodiment of the present invention is realized by connecting at least two different amplifier paths in parallel. These amplifier paths have a plurality of amplifier stage circuits of the same number and connected in series, but the amplifier stage circuits of the same order in these amplifier paths do not have exactly the same circuit structure / parameters, but each has at least one different circuit structure / parameter (for example, different transistor size, bias, phase, signal gain, etc.) and belongs to an asymmetric circuit structure. The embodiment of the present invention uses at least two different amplifier paths of an asymmetric circuit structure as an asymmetric power combination, and designs the corresponding output impedances of the two different amplifier paths to be roughly complex conjugate matching (if there are more than two paths, the combined output impedance only needs to be closely matched with the load to achieve an effective asymmetric power combination) and the reverse isolation of each amplifier path is better than a specific maximum value (for example, 35dB, which depends on the operating frequency), so that the RF power amplifier has a sufficiently wide transmission bandwidth and peak power added efficiency, thereby providing sufficient transmission rate, signal gain and lower power consumption. On the other hand, the control circuit can also adjust the adjustable circuit elements in the impedance circuit accordingly through the detection circuit through the electrical characteristics of the RF signal or the amplified RF signal (such as signal frequency, signal power, etc.), thereby dynamically adjusting the output impedance of the RF power amplifier and further improving the performance of the RF power amplifier.

Claims

1. A radio frequency power amplifier, characterized in that: include: An input terminal for receiving a radio frequency signal; at least two amplifier paths, each amplifier path coupled to the input terminal, each amplifier path configured to amplify the RF signal to generate a corresponding amplified RF signal; an asymmetric power combining circuit coupled to the amplifier paths for combining the amplified RF signals generated by the amplifier paths to generate a combined RF signal; as well as an output terminal, for outputting the combined radio frequency signal, Each of the amplifier paths simultaneously generates the corresponding amplified RF signal, and the reverse isolation of each of the amplifier paths is better than 35 dB.

2. The radio frequency power amplifier according to claim 1, characterized in that: Each of the amplifier paths includes a plurality of amplifier stage circuits connected in series.

3. The radio frequency power amplifier according to claim 2, characterized in that: The number of the amplifier stage circuits connected in series in each amplifier path is greater than or equal to 3.

4. The radio frequency power amplifier according to claim 2, characterized in that: The last-stage amplifier circuit in each of the amplifier paths is a common-source amplifier, a common-emitter amplifier, a cascade amplifier, a double-stacked amplifier, a cascade amplifier in which a common-source amplifier is connected in series to a common-gate amplifier, or a multi-stacked transistor amplifier.

5. The radio frequency power amplifier according to claim 2, characterized in that: The amplifier stage circuits connected in series in each of the amplifier paths are common source amplifiers, common emitter amplifiers, or a combination of common source amplifiers, common emitter amplifiers, cascade amplifiers, double stack amplifiers, and multi-stack transistor amplifiers.

6. The radio frequency power amplifier according to claim 2, characterized in that: The amplifier stage circuits with the same order in each of the amplifier paths have different transistor sizes.

7. The radio frequency power amplifier according to claim 2, characterized in that: The last-stage amplifier circuit in each amplifier path includes: A first transistor and a second transistor stacked on each other; A first capacitor, through which the control terminal of the second transistor is coupled to a reference voltage terminal; and A first resistor bias circuit, the control end of the second transistor is coupled to the working voltage end through the first resistor bias circuit.

8. The radio frequency power amplifier according to claim 2, characterized in that: The last-stage amplifier circuit in each amplifier path includes: A first transistor and a second transistor; A first capacitor, through which the control terminal of the second transistor is coupled to a reference voltage terminal; and The first filter circuit is coupled between the control end of the second transistor and the second end of the second transistor, wherein the first end of the second transistor serves as the signal output end of the amplifier stage circuit, and the second end of the second transistor is coupled to the first end of the first transistor.

9. The radio frequency power amplifier according to claim 2, characterized in that: The amplifier stage circuits connected in series in each amplifier path are used to receive an operating voltage; and the operating voltage of the last-stage amplifier stage circuit in each amplifier path is greater than the operating voltages of the other-stage amplifier stage circuits.

10. The radio frequency power amplifier according to claim 2, characterized in that: One of the amplifier stage circuits includes a double stack amplifier, the double stack amplifier includes a first transistor and a second transistor stacked on each other, and one of the amplifier stage circuits further includes: A first capacitor, through which the control terminal of the second transistor is coupled to a reference voltage terminal; and A first resistor bias circuit, the control end of the second transistor is coupled to a working voltage end through the first resistor bias circuit.

11. The radio frequency power amplifier according to claim 2, characterized in that: One of the amplifier stage circuits includes a cascade amplifier, the cascade amplifier includes a first transistor and a second transistor, and one of the amplifier stage circuits further includes: A first capacitor, through which the control terminal of the second transistor is coupled to a reference voltage terminal; and The first filter circuit is coupled between the control end of the second transistor and the second end of the second transistor, wherein the first end of the second transistor serves as the signal output end of the amplifier stage circuit, and the second end of the second transistor is coupled to the first end of the first transistor.

12. The radio frequency power amplifier according to claim 1, characterized in that: Each of the amplifier paths includes at least one amplifier stage circuit, the at least one amplifier stage circuit is coupled to the asymmetric power combination circuit, and the at least one amplifier stage circuit includes: A first transistor and a second transistor stacked on each other; and A first resistor bias circuit, the control end of the second transistor is coupled to a working voltage end through the resistor bias circuit.

13. The radio frequency power amplifier according to claim 1, characterized in that: Each of the amplifier paths includes at least one amplifier stage circuit, the at least one amplifier stage circuit is coupled to the asymmetric power combination circuit, and the at least one amplifier stage circuit includes: A first transistor and a second transistor; and The first filter circuit is coupled between the control end of the second transistor and the second end of the second transistor, wherein the first end of the second transistor serves as the signal output end of the amplifier stage circuit, and the second end of the second transistor is coupled to the first end of the first transistor.

14. The radio frequency power amplifier according to claim 1, characterized in that: The at least two amplifier paths include a first amplifier path and a second amplifier path, and the asymmetric power combination circuit includes: A first impedance circuit coupled between the output terminal and the first amplifier path, wherein the first impedance circuit has a first impedance when the output terminal is used as a reference; and A second impedance circuit is coupled between the output terminal and the second amplifier path, wherein the second impedance circuit has a second impedance when the output terminal is used as a reference. The first impedance and the second impedance are substantially complex conjugate matched.

15. The radio frequency power amplifier according to claim 14, characterized in that: Also includes: a load circuit coupled to the output terminal, The equivalent impedance formed by the first impedance and the second impedance is equal to the impedance of the load circuit.

16. The radio frequency power amplifier according to claim 14, characterized in that: The first impedance corresponding to the first impedance circuit and the second impedance corresponding to the second impedance circuit are variable, and the RF power amplifier further includes: a detection circuit for detecting the electrical characteristics of the RF signal or the combined RF signal and generating a detection signal; and The control circuit is coupled to the detection circuit, and is used for controlling at least part of the circuit elements in the first impedance circuit and the second impedance circuit according to the detection signal to adjust the first impedance and the second impedance.

17. The radio frequency power amplifier according to claim 1, characterized in that: wherein the at least two amplifier paths include a first amplifier path, a second amplifier path, a third amplifier path, and a fourth amplifier path, The asymmetric power combining circuit includes a first sub-power combining circuit and a second sub-power combining circuit, wherein the first sub-power combining circuit is used to combine two first amplified RF signals generated by the first amplifier path and the second amplifier path to generate a first combined RF signal, and the second sub-power combining circuit is used to combine two second amplified RF signals generated by the third amplifier path and the fourth amplifier path to generate a second combined RF signal, wherein the first combined RF signal and the second combined RF signal are superimposed to form the combined RF signal.

18. The radio frequency power amplifier according to claim 1, characterized in that: The reverse isolation is the amplifier reverse transmission response measured from the output of the amplifier path to its input.

19. A radio frequency power amplifier, characterized in that: include: An input terminal, receiving a radio frequency signal; at least two amplifier paths, each amplifier path coupled to the input terminal, each amplifier path configured to amplify the RF signal to generate a corresponding amplified RF signal; as well as an asymmetric power combining circuit coupled to the amplifier paths for combining the amplified RF signals generated by the amplifier paths to generate a combined RF signal, Each of the amplifier paths simultaneously generates a corresponding amplified RF signal, and each of the amplifier paths comprises: A first transistor, a second transistor and a third transistor stacked on each other; a first capacitor, wherein the control terminal of the second transistor is coupled to a reference voltage terminal through the first capacitor; a first filter circuit coupled between the control terminal of the second transistor and the second terminal of the second transistor, wherein the second terminal of the second transistor is coupled to the first terminal of the first transistor, A second capacitor, the control end of the third transistor is coupled to the reference voltage end through the second capacitor; The second filter circuit is coupled between the control end of the third transistor and the second end of the third transistor, wherein the first end of the third transistor serves as the signal output end of the amplifier path, and the second end of the third transistor is coupled to the first end of the second transistor.

20. The radio frequency power amplifier according to claim 19, characterized in that: The reverse isolation of each of the amplifier paths is better than 35dB.

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