Radio frequency power amplifier and radio frequency chip

Abstract

The invention is suitable for the technical field of communication, and particularly relates to a radio frequency power amplifier and a radio frequency chip. The radio frequency power amplifier comprises a power amplification unit, an output matching network, a power detection unit, a comparison unit and an input attenuation circuit, the input end of the power amplification unit serves as the input end of the radio frequency power amplifier and is used for receiving radio frequency signals, and the output end of the power amplification unit is connected with the input end of the output matching network and the input end of the power detection unit. The output end of the output matching network serves as the output end of the radio frequency power amplifier and is used for outputting a radio frequency signal to an external antenna. Compared with the prior art, the radio frequency power amplifier can effectively solve the problem that the radio frequency power amplifier is broken down and burnt out due to too high input power or serious load mismatch, and the linearity of the radio frequency power amplifier is effectively improved.

Description

Technical Field

[0001] The present invention is applicable to the field of communication technology, and in particular relates to a radio frequency power amplifier and a radio frequency chip. Background Art

[0002] The power amplifier can be used to output power to the mobile phone antenna. Since the mobile phone antenna will not always be 50 ohms, the antenna will deviate from 50 ohms when the mobile phone is close to a wall or in a basement. At this time, due to the deviation from 50 ohms, the output power of the power amplifier is not as high as when it is 50 ohms. At this time, due to the loop control of the mobile phone, the user's communication quality needs to be guaranteed. At this time, the mobile phone platform will increase the input power of the power amplifier, thereby preventing the antenna power from being reduced and maintaining the communication quality between the mobile phone and the base station. If it continues to deviate from 50 ohms, due to the existence of this mechanism, the input power of the power amplifier will increase. At this time, the output of the power amplifier faces high power and high mismatch, and the power tube will eventually be broken down in the morning.

[0003] In the related art, a diode is often used at the input end of the power amplifier for protection to prevent the input power from being too high. Figure 1 As shown, Figure 1 The circuit structure of a radio frequency power amplifier using a diode as a protection circuit in the related art is shown in FIG. Figure 1 The input protection circuit consists of four diodes. Figure 2 The circuit structure shown, Figure 2 The circuit structure of a radio frequency power amplifier using a diode as a protection circuit in the related art is shown in FIG. Figure 2 , the input protection consists of a structure consisting of two diodes.

[0004] However, if Figure 1 The circuit structure shown in the figure has four diodes forming an input protection circuit. When the input power increases to about 10dBm, the diodes will work to clamp the input power and protect the amplifier. However, the input power of 10dBm is usually relatively high, and the power amplifier will be pushed to saturation. The output amplitude is too large, which may easily cause the output tube to break down. Figure 2 The two diode protections shown in the figure, when the input power is about 4dBm, the diodes work. At this time, the input power is not high. Facing a power amplifier with a lower gain, for example, a power amplifier with a gain of 26dB, the output power OUT1 of the power amplifier is 30dBm. At this time, the power loss caused by the mobile phone wiring loss and the antenna switch loss is not taken into account. These two types of losses are generally 2~3dB. At this time, the antenna power is 28dbm, which cannot meet the current power requirement of 29dBm for mobile phones.

[0005] Therefore, a new RF power amplifier and RF chip are urgently needed to solve the above technical problems. Summary of the invention

[0006] The present invention provides a radio frequency power amplifier and a radio frequency chip, aiming to solve the problem that the radio frequency power amplifier is broken down and burned out due to excessive input power or serious load mismatch, and effectively improve the linearity of the radio frequency power amplifier.

[0007] In a first aspect, the present invention provides a radio frequency power amplifier, the radio frequency power amplifier comprising a power amplification unit, an output matching network, a power detection unit, a comparison unit and an input attenuation circuit; The input end of the power amplification unit serves as the input end of the RF power amplifier and is used to receive the RF signal. The output end of the power amplification unit is respectively connected to the input end of the output matching network and the input end of the power detection unit. The output end of the output matching network serves as the output end of the radio frequency power amplifier, and is used to output a radio frequency signal; The output end of the power detection unit is connected to the input end of the comparison unit; the power detection unit is used to detect the output power of the power amplification unit; The first output end of the comparison unit is connected to the first input end of the input attenuation circuit, and the second output end of the comparison unit is connected to the second input end of the input attenuation circuit; the comparison unit is used to determine whether the output power of the power amplification unit exceeds a preset threshold; The third input terminal of the input attenuation circuit is used to receive a radio frequency signal, the output terminal of the input attenuation circuit is grounded, and the input attenuation circuit is used to adjust the input power of the power amplification unit.

[0008] Preferably, the power amplification unit includes a first capacitor, a second capacitor, a first resistor, a second resistor, a first inductor, a second inductor, a first transistor and a second transistor; The first end of the first capacitor serves as the input end of the power amplifying unit, and the second end of the first capacitor is connected to the input end of the first transistor; the first end of the first resistor is connected to the second end of the first capacitor, and the second end of the first resistor is used to connect to a first bias voltage, the ground end of the first transistor is grounded, the output end of the first transistor is respectively connected to the first end of the first inductor and the first end of the second capacitor, and the second end of the first inductor is used to connect to a first power supply voltage; the second end of the second capacitor is connected to the input end of the second transistor, the first end of the second resistor is connected to the second end of the second capacitor, and the second end of the second resistor is used to connect to a second bias voltage, the ground end of the second transistor is grounded, the output end of the second transistor serves as the output end of the power amplifying unit, the first end of the second inductor is connected to the output end of the second transistor, and the second end of the second inductor is used to connect to a second power supply voltage.

[0009] Preferably, the power detection unit includes a third capacitor, a fourth capacitor, a third resistor, a fourth resistor, a fifth resistor and a third transistor; The first end of the third capacitor serves as the input end of the power detection unit, the second end of the third capacitor is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the input end of the third transistor, the first end of the third resistor is connected to the second end of the fourth resistor, the second end of the third resistor is used to connect a third bias voltage, the output end of the third transistor is used to connect a second power supply voltage, the ground end of the third transistor serves as the output end of the power detection unit, the first end of the fifth resistor and the first end of the fourth capacitor are respectively connected to the ground end of the third transistor, and the second end of the fifth resistor and the second end of the fourth capacitor are respectively grounded.

[0010] Preferably, the comparison unit includes a sixth resistor, a fifth capacitor, a first comparator and a second comparator; the first end of the sixth resistor serves as the input end of the comparison unit, the second end of the sixth resistor is respectively connected to the positive input end of the first comparator and the positive input end of the second comparator, the first end of the fifth capacitor is connected to the second end of the sixth resistor, the second end of the fifth capacitor is grounded, the negative input end of the first comparator is used to connect to a first reference voltage, the output end of the first comparator serves as the first output end of the comparison unit, the negative input end of the second comparator is used to connect to a second reference voltage, and the output end of the second comparator serves as the second output end of the comparison unit.

[0011] Preferably, the input attenuation circuit includes a sixth capacitor, a seventh capacitor, a seventh resistor, an eighth resistor, a first MOS tube and a second MOS tube; the gate of the first MOS tube serves as the first input end of the input attenuation circuit, the source of the first MOS tube is grounded, the drain of the first MOS tube is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the first end of the sixth capacitor, the second end of the sixth capacitor serves as the third input end of the input attenuation circuit, the first end of the seventh capacitor is connected to the second end of the sixth capacitor, the second end of the seventh capacitor is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the drain of the second MOS tube, the gate of the second MOS tube serves as the second input end of the input attenuation circuit, and the source of the second MOS tube is grounded.

[0012] Preferably, the first transistor, the second transistor and the third transistor are all field effect transistors; The input end of the first transistor, the input end of the second transistor and the input end of the third transistor are all gates of the field effect transistor, the output end of the first transistor, the output end of the second transistor and the output end of the third transistor are all drains of the field effect transistor, and the ground end of the first transistor, the ground end of the second transistor and the ground end of the third transistor are all sources of the field effect transistor.

[0013] Preferably, the first transistor, the second transistor and the third transistor are all triodes; The input end of the first transistor, the input end of the second transistor and the input end of the third transistor are all bases of the transistor, the output end of the first transistor, the output end of the second transistor and the output end of the third transistor are all collectors of the transistor, and the ground end of the first transistor, the ground end of the second transistor and the ground end of the third transistor are all emitters of the transistor.

[0014] In a second aspect, the present invention further provides a radio frequency chip, wherein the radio frequency chip comprises a radio frequency power amplifier as described in any one of the above embodiments.

[0015] Compared with the prior art, the RF power amplifier of the present invention includes a power amplification unit, an output matching network, a power detection unit, a comparison unit and an input attenuation circuit; the input end of the power amplification unit is used as the input end of the RF power amplifier for receiving RF signals, and the output end of the power amplification unit is respectively connected to the input end of the output matching network and the input end of the power detection unit; the output end of the output matching network is used as the output end of the RF power amplifier for outputting RF signals to an external antenna; the output end of the power detection unit is connected to the input end of the comparison unit; the first output end of the comparison unit is connected to the first input end of the input attenuation circuit, and the second output end of the comparison unit is connected to the second input end of the input attenuation circuit; the third input end of the input attenuation circuit is used to receive RF signals, the output end of the input attenuation circuit is grounded, and the input attenuation circuit is used to adjust the output power of the power amplification unit. In this way, the RF power amplifier of the present invention can effectively solve the problem of the RF power amplifier being broken down and burned due to excessive input power or serious load mismatch, and effectively improve the linearity of the RF power amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings: Figure 1 The circuit structure of a radio frequency power amplifier using a diode as a protection circuit in the related art is shown in FIG. Figure 1 ; Figure 2 The circuit structure of a radio frequency power amplifier using a diode as a protection circuit in the related art is shown in FIG. Figure 2 ; Figure 3 The schematic diagram of the partial circuit structure of the radio frequency power amplifier provided by the embodiment of the present invention is Figure 1 ; Figure 4 1 is a schematic diagram of the circuit structure of an input attenuation circuit of a radio frequency power amplifier provided in an embodiment of the present invention; Figure 5 is a waveform diagram of a radio frequency power amplifier provided in an embodiment of the present invention; Figure 6 The schematic diagram of the partial circuit structure of the radio frequency power amplifier provided by the embodiment of the present invention is Figure 2 .

[0017] In the figure, 100 is a radio frequency power amplifier, 101 is a power amplification unit, 102 is an output matching network, 103 is a power detection unit, 104 is a comparison unit, and 105 is an input attenuation circuit. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Embodiment 1 Please refer to Figure 3-Figure 6 The present invention provides a radio frequency power amplifier 100, wherein the radio frequency power amplifier 100 includes a power amplification unit 101, an output matching network 102, a power detection unit 103, a comparison unit 104 and an input attenuation circuit 105; The input end of the power amplification unit 101 serves as the input end of the RF power amplifier 100 and is used to receive a RF signal. The output end of the power amplification unit 101 is respectively connected to the input end of the output matching network 102 and the input end of the power detection unit 103; The output end of the output matching network 102 is used as the output end of the RF power amplifier 100 to output the RF signal to the external antenna (i.e. Figure 3 and Figure 6 OUT1 in the output).

[0020] The output end of the power detection unit 103 is connected to the input end of the comparison unit 104; the power detection unit 103 is used to detect the output power of the power amplification unit 101; The first output terminal (Vout1) of the comparison unit 104 is connected to the first input terminal of the input attenuation circuit 105, and the second output terminal (Vout2) of the comparison unit 104 is connected to the second input terminal of the input attenuation circuit 105; the comparison unit 104 is used to determine whether the output power of the power amplification unit 101 exceeds a preset threshold; The third input terminal of the input attenuation circuit 105 is used to receive a radio frequency signal. The output terminal of the input attenuation circuit 105 is grounded. The input attenuation circuit 105 is used to adjust the input power of the power amplification unit 101 .

[0021] In the embodiment of the present invention, the power amplification unit 101 includes a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a first inductor L1, a second inductor L2, a first transistor Q1 and a second transistor Q2; The first end of the first capacitor C1 serves as the input end of the power amplifying unit 101, the second end of the first capacitor C1 is connected to the input end of the first transistor Q1, the first end of the first resistor R1 is connected to the second end of the first capacitor C1, the second end of the first resistor R1 is used to connect to the first bias voltage VBIAS1, the ground end of the first transistor Q1 is grounded, the output end of the first transistor Q1 is respectively connected to the first end of the first inductor L1 and the first end of the second capacitor C2, the second end of the first inductor L1 is used to connect to the first power supply voltage VCC1, the second end of the second capacitor C2 is connected to the input end of the second transistor Q2, the first end of the second resistor R2 is connected to the second end of the second capacitor C2, the second end of the second resistor R2 is connected to the second bias voltage VBIAS2, the ground end of the second transistor Q2 is grounded, the output end of the second transistor Q2 serves as the output end of the power amplifying unit 101, the first end of the second inductor L2 is connected to the output end of the second transistor Q2, and the second end of the second inductor L2 is used to connect to the second power supply voltage VCC2.

[0022] In the embodiment of the present invention, the power detection unit 103 includes a third capacitor C3, a fourth capacitor C4, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a third transistor Q3; The first end of the third capacitor C3 serves as the input end of the power detection unit 103, the second end of the third capacitor C3 is connected to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is connected to the input end of the third transistor Q3, the first end of the third resistor R3 is connected to the second end of the fourth resistor R4, the second end of the third resistor R3 is used to connect the third bias voltage VBIAS3, the output end of the third transistor Q3 is used to connect the second power supply voltage VCC2, the ground end of the third transistor Q3 serves as the output end of the power detection unit 103, the first end of the fifth resistor R5 and the first end of the fourth capacitor C4 are respectively connected to the ground end of the third transistor Q3, and the second end of the fifth resistor R5 and the second end of the fourth capacitor C4 are respectively grounded.

[0023] It should be noted that the first bias voltage VIBAS1, the second bias voltage VIBAS2 and the third bias voltage VIBAS3 can be set according to actual conditions, and their sizes can be the same or different. The first power supply voltage VCC1 and the second power supply voltage VCC2 can be set according to actual conditions, and their sizes can be the same or different.

[0024] In the embodiment of the present invention, the comparison unit 104 includes a sixth resistor R6, a fifth capacitor C5, a first comparator CMP1 and a second comparator CMP2; the first end of the sixth resistor R6 serves as the input end of the comparison unit 104, the second end of the sixth resistor R6 is respectively connected to the positive input end of the first comparator CMP1 and the positive input end of the second comparator CMP2, the first end of the fifth capacitor C5 is connected to the second end of the sixth resistor R6, the second end of the fifth capacitor C5 is grounded, the negative input end of the first comparator CMP1 is used to connect the first reference voltage Vref1, the output end of the first comparator CMP1 serves as the first output end of the comparison unit 104, the negative input end of the second comparator CMP2 is used to connect the second reference voltage Vref2, and the output end of the second comparator CMP2 serves as the second output end of the comparison unit 104.

[0025] In the embodiment of the present invention, the input attenuation circuit 105 includes a sixth capacitor C6, a seventh capacitor C7, a seventh resistor R7, an eighth resistor R8, a first MOS transistor and a second MOS transistor; the gate of the first MOS transistor serves as the first input end of the input attenuation circuit 105, the source of the first MOS transistor is grounded, the drain of the first MOS transistor is connected to the first end of the seventh resistor R7, the second end of the seventh resistor R7 is connected to the first end of the sixth capacitor C6, the second end of the sixth capacitor C6 serves as the third input end of the input attenuation circuit 105, the first end of the seventh capacitor C7 is connected to the second end of the sixth capacitor C6, the second end of the seventh capacitor C7 is connected to the first end of the eighth resistor R8, the second end of the eighth resistor R8 is connected to the drain of the second MOS transistor, the gate of the second MOS transistor serves as the second input end of the input attenuation circuit 105, and the source of the second MOS transistor is grounded.

[0026] In the embodiment of the present invention, it is feasible that the first transistor Q1, the second transistor Q2 and the third transistor Q3 are all field effect transistors or triodes.

[0027] When the first transistor Q1, the second transistor Q2 and the third transistor Q3 are all field effect transistors; the input end of the first transistor Q1, the input end of the second transistor Q2 and the input end of the third transistor Q3 are all gates of the field effect transistors, the output end of the first transistor Q1, the output end of the second transistor Q2 and the output end of the third transistor Q3 are all drains of the field effect transistors, and the ground end of the first transistor Q1, the ground end of the second transistor Q2 and the ground end of the third transistor Q3 are all sources of the field effect transistors. For details, please refer to Figure 6 , Figure 6The schematic diagram of the partial circuit structure of the radio frequency power amplifier provided by the embodiment of the present invention is Figure 2 In the figure, the first transistor Q1, the second transistor Q2 and the third transistor Q3 are all field effect transistors, and correspond to the first field effect transistor, the second field effect transistor and the third field effect transistor respectively; wherein the gate of the first field effect transistor serves as the input end of the first transistor Q1, the source of the first field effect transistor serves as the ground end of the first transistor Q1, and the drain of the first field effect transistor serves as the output end of the first transistor Q1; The gate of the second field effect tube serves as the input terminal of the second transistor Q2, the source of the second field effect tube serves as the ground terminal of the second transistor Q2, and the drain of the second field effect tube serves as the output terminal of the second transistor Q2; The gate of the third field effect tube serves as the input terminal of the third transistor Q3, the source of the third field effect tube serves as the ground terminal of the third transistor Q3, and the drain of the third field effect tube serves as the output terminal of the third transistor Q3.

[0028] When the first transistor Q1, the second transistor Q2 and the third transistor Q3 are all triodes; the input end of the first transistor Q1, the input end of the second transistor Q2 and the input end of the third transistor Q3 are all bases of the triodes, the output end of the first transistor Q1, the output end of the second transistor Q2 and the output end of the third transistor Q3 are all collectors of the triodes, and the ground end of the first transistor Q1, the ground end of the second transistor Q2 and the ground end of the third transistor Q3 are all emitters of the triodes. Please refer to Figure 3 , Figure 3 The schematic diagram of the partial circuit structure of the radio frequency power amplifier provided by the embodiment of the present invention is Figure 1 The first transistor Q1, the second transistor Q2 and the third transistor Q3 are all triodes, and correspond to the first triode, the second triode and the third triode respectively; wherein the base of the first triode serves as the input end of the first transistor Q1, the collector of the first triode serves as the output end of the first transistor Q1, and the emitter of the first triode serves as the ground end of the first transistor Q1; The base of the second transistor serves as the input terminal of the second transistor Q2, the collector of the second transistor serves as the output terminal of the second transistor Q2, and the emitter of the second transistor serves as the ground terminal of the second transistor Q2; The base of the third triode serves as the input end of the third transistor Q3, the collector of the third triode serves as the output end of the third transistor Q3, and the emitter of the third triode serves as the ground end of the third transistor Q3.

[0029] like Figure 5 As shown, Figure 5 1 is a waveform diagram of the RF power amplifier 100 provided by an embodiment of the present invention. When the amplitude at the node OUT2 increases, the voltage Vpeak output by the power detection circuit will also increase when the node OUT2 is a positive swing. When the node OUT2 is a negative swing, the voltage Vpeak output by the power detection circuit is stabilized by the fourth capacitor C4, and the voltage drop is very small. After filtering by the sixth resistor R6 and the fifth capacitor C5, the node V3 waveform is obtained.

[0030] Compared with the prior art, the RF power amplifier of the present invention includes a power amplification unit, an output matching network, a power detection unit, a comparison unit and an input attenuation circuit; the input end of the power amplification unit is used as the input end of the RF power amplifier for receiving RF signals, and the output end of the power amplification unit is respectively connected to the input end of the output matching network and the input end of the power detection unit; the output end of the output matching network is used as the output end of the RF power amplifier for outputting RF signals to an external antenna; the output end of the power detection unit is connected to the input end of the comparison unit; the first output end of the comparison unit is connected to the first input end of the input attenuation circuit, and the second output end of the comparison unit is connected to the second input end of the input attenuation circuit; the third input end of the input attenuation circuit is used to receive RF signals, the output end of the input attenuation circuit is grounded, and the input attenuation circuit is used to adjust the output power of the power amplification unit. In this way, the RF power amplifier of the present invention can effectively solve the problem of the RF power amplifier being broken down and burned due to excessive input power or serious load mismatch, and effectively improve the linearity of the RF power amplifier.

[0031] Embodiment 2 An embodiment of the present invention further provides a radio frequency chip, which includes the radio frequency power amplifier 100 as described in the above embodiment and can achieve the same technical effect. Please refer to the description in the above embodiment and will not be repeated here.

[0032] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0033] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only the preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation manner. The above-mentioned specific implementation manner is only illustrative rather than restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms and equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A radio frequency power amplifier, characterized in that: The radio frequency power amplifier comprises a power amplification unit, an output matching network, a power detection unit, a comparison unit and an input attenuation circuit; The input end of the power amplification unit serves as the input end of the RF power amplifier and is used to receive the RF signal. The output end of the power amplification unit is respectively connected to the input end of the output matching network and the input end of the power detection unit. The output end of the output matching network serves as the output end of the radio frequency power amplifier, and is used to output a radio frequency signal; The output end of the power detection unit is connected to the input end of the comparison unit; the power detection unit is used to detect the output power of the power amplification unit; The first output end of the comparison unit is connected to the first input end of the input attenuation circuit, and the second output end of the comparison unit is connected to the second input end of the input attenuation circuit; the comparison unit is used to determine whether the output power of the power amplification unit exceeds a preset threshold; The third input terminal of the input attenuation circuit is used to receive a radio frequency signal, the output terminal of the input attenuation circuit is grounded, and the input attenuation circuit is used to adjust the input power of the power amplification unit.

2. The radio frequency power amplifier according to claim 1, characterized in that: The power amplification unit includes a first capacitor, a second capacitor, a first resistor, a second resistor, a first inductor, a second inductor, a first transistor and a second transistor; The first end of the first capacitor serves as the input end of the power amplifying unit, and the second end of the first capacitor is connected to the input end of the first transistor; the first end of the first resistor is connected to the second end of the first capacitor, and the second end of the first resistor is used to connect to a first bias voltage, the ground end of the first transistor is grounded, the output end of the first transistor is respectively connected to the first end of the first inductor and the first end of the second capacitor, and the second end of the first inductor is used to connect to a first power supply voltage; the second end of the second capacitor is connected to the input end of the second transistor, the first end of the second resistor is connected to the second end of the second capacitor, and the second end of the second resistor is connected to a second bias voltage; the ground end of the second transistor is grounded, the output end of the second transistor serves as the output end of the power amplifying unit, the first end of the second inductor is connected to the output end of the second transistor, and the second end of the second inductor is used to connect to a second power supply voltage.

3. The radio frequency power amplifier according to claim 2, characterized in that: The power detection unit includes a third capacitor, a fourth capacitor, a third resistor, a fourth resistor, a fifth resistor and a third transistor; The first end of the third capacitor serves as the input end of the power detection unit, and the second end of the third capacitor is connected to the first end of the fourth resistor; the second end of the fourth resistor is connected to the input end of the third transistor, the first end of the third resistor is connected to the second end of the fourth resistor, and the second end of the third resistor is used to connect to a third bias voltage; the output end of the third transistor is used to connect to the second power supply voltage, and the ground end of the third transistor serves as the output end of the power detection unit; The first end of the fifth resistor and the first end of the fourth capacitor are respectively connected to the ground terminal of the third transistor, and the second end of the fifth resistor and the second end of the fourth capacitor are respectively grounded.

4. The radio frequency power amplifier according to claim 1, characterized in that: The comparison unit includes a sixth resistor, a fifth capacitor, a first comparator and a second comparator; the first end of the sixth resistor serves as the input end of the comparison unit, the second end of the sixth resistor is respectively connected to the positive input end of the first comparator and the positive input end of the second comparator, the first end of the fifth capacitor is connected to the second end of the sixth resistor, and the second end of the fifth capacitor is grounded; the negative input end of the first comparator is used to connect to a first reference voltage, the output end of the first comparator serves as the first output end of the comparison unit, the negative input end of the second comparator is used to connect to a second reference voltage, and the output end of the second comparator serves as the second output end of the comparison unit.

5. The radio frequency power amplifier according to claim 1, characterized in that: The input attenuation circuit includes a sixth capacitor, a seventh capacitor, a seventh resistor, an eighth resistor, a first MOS transistor and a second MOS transistor; the gate of the first MOS transistor serves as the first input end of the input attenuation circuit, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is connected to the first end of the seventh resistor; the second end of the seventh resistor is connected to the first end of the sixth capacitor, and the second end of the sixth capacitor serves as the third input end of the input attenuation circuit; the first end of the seventh capacitor is connected to the second end of the sixth capacitor, and the second end of the seventh capacitor is connected to the first end of the eighth resistor; the second end of the eighth resistor is connected to the drain of the second MOS transistor, the gate of the second MOS transistor serves as the second input end of the input attenuation circuit, and the source of the second MOS transistor is grounded.

6. The radio frequency power amplifier according to claim 3, characterized in that: The first transistor, the second transistor and the third transistor are all field effect transistors; The input end of the first transistor, the input end of the second transistor and the input end of the third transistor are all gates of the field effect transistor; the output end of the first transistor, the output end of the second transistor and the output end of the third transistor are all drains of the field effect transistor; The ground terminal of the first transistor, the ground terminal of the second transistor and the ground terminal of the third transistor are all sources of the field effect transistor.

7. The radio frequency power amplifier according to claim 3, characterized in that: The first transistor, the second transistor and the third transistor are all triodes; The input end of the first transistor, the input end of the second transistor and the input end of the third transistor are all bases of the transistor; the output end of the first transistor, the output end of the second transistor and the output end of the third transistor are all collectors of the transistor; the ground end of the first transistor, the ground end of the second transistor and the ground end of the third transistor are all emitters of the transistor.

8. A radio frequency chip, characterized in that: The radio frequency chip includes a radio frequency power amplifier as described in any one of claims 1 to 7 above.

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