Radio frequency power amplifier

Abstract

The invention relates to the technical field of wireless communication, and provides a radio frequency power amplifier which comprises a power amplifying circuit, a first biasing circuit, a second biasing circuit and a feedback circuit. The first biasing circuit comprises a first resistor, a first voltage division circuit and a first triode, the first end of the first resistor is used for being connected to an external first power supply, and the second end of the first resistor is connected with the first end of the first voltage division circuit and the base electrode of the first triode; the second biasing circuit comprises a second resistor, a second voltage division circuit and a second triode; the first end of the second resistor is connected with the second end of the first resistor, the second end of the second resistor is connected with the second voltage division circuit and the second triode, and the second triode is connected with the feedback circuit and the power amplification circuit. According to the radio frequency power amplifier, power amplifier gain and linear performance fluctuation caused by temperature change can be reduced, and simplified circuit layout and smaller chip area occupation can be realized.

Description

Technical Field

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

[0002] A radio frequency power amplifier (Power Amplifier, abbreviated as PA) is an important component of a communication system. As the last amplification unit in the transmitting channel, its function is to amplify a low-power radio frequency signal and then send it to the antenna for transmission. With the rapid development of wireless communication (such as communication protocols like 5G and wifi7), higher requirements are imposed on the linear performance of radio frequency power amplifiers. However, when the amplitude modulation-amplitude modulation curve (AM-AM) of a radio frequency power amplifier approaches the output P-1dB power, a large collapse usually occurs, resulting in amplitude distortion and a significant deterioration of linear performance.

[0003] In the prior art, a power amplifier includes a signal input end, an amplifier circuit, and a signal output end connected in sequence, and a power boost (power gain boost technology) bias circuit for providing a bias current to the amplifier circuit. The power boost bias circuit can make the collapsed AM-AM curve flatter when the output power of the power amplifier approaches the saturation power.

[0004] However, due to the introduction of the power boost circuit, the performance of the PA is more sensitive to temperature, that is, the gain change and linear performance change of the power amplifier under environmental temperature changes such as high and low temperatures are increased. This kind of temperature sensitivity will cause the deteriorated linear performance and gain of the PA to not meet the communication requirements at high or low temperatures. Summary of the Invention

[0005] Aiming at the above deficiencies of the prior art, the present invention proposes a radio frequency power amplifier to solve the problem of temperature sensitivity of existing radio frequency power amplifiers.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: An embodiment of the present invention provides a radio frequency power amplifier, which includes a power amplification circuit, a first bias circuit, a second bias circuit, and a feedback circuit; the input unit of the power amplification circuit is used to access a radio frequency signal, and the output end of the power amplification circuit is used to amplify and output the radio frequency signal; the first bias circuit and the second bias circuit are respectively used to provide a bias current to the power amplification circuit; the first end of the feedback circuit is connected to the output end of the second bias circuit, and the second end of the feedback circuit is connected to the output end of the power amplification circuit. The feedback circuit is used to receive the signal output by the power amplification circuit and feedback it to the second bias circuit; The first bias circuit includes a first resistor, a first voltage-dividing circuit, and a first triode; a first end of the first resistor is used to connect to an external first power supply, a second end of the first resistor is respectively connected to a first end of the first voltage-dividing circuit and a base of the first triode, a second end of the first voltage-dividing circuit is grounded, an emitter of the first triode is connected to an input end of the power amplification circuit, and a collector of the first triode is used to connect to an external second power supply; The second bias circuit includes a second resistor, a second voltage-dividing circuit, and a second triode; a first end of the second resistor is connected to the second end of the first resistor, a second end of the second resistor is respectively connected to a first end of the second voltage-dividing circuit and a base of the second triode, a collector of the second triode is used to connect to the second power supply, a second end of the second voltage-dividing circuit is grounded, and an emitter of the second triode is respectively connected to a first end of the feedback circuit and an input end of the power amplification circuit.

[0007] Preferably, the first voltage-dividing circuit includes a first diode and a second diode, a positive electrode of the first diode serves as the first end of the first voltage-dividing circuit, a negative electrode of the first diode is connected to a positive electrode of the second diode, and a negative electrode of the second diode serves as the second end of the first voltage-dividing circuit; The second voltage-dividing circuit includes a third diode and a fourth diode, a positive electrode of the third diode serves as the first end of the second voltage-dividing circuit, a negative electrode of the third diode is connected to a positive electrode of the fourth diode, and a negative electrode of the fourth diode serves as the second end of the second voltage-dividing circuit.

[0008] Preferably, the radio frequency power amplifier further includes a first capacitor, a first end of the first capacitor is connected to the base of the first triode, and a second end of the first capacitor is grounded.

[0009] Preferably, the radio frequency power amplifier further includes a second capacitor, a first end of the second capacitor is connected to the base of the second triode, and a second end of the second capacitor is grounded.

[0010] Preferably, the radio frequency power amplifier further includes a third resistor, a first end of the third resistor is connected to the emitter of the first triode, and a second end of the third resistor is connected to the input end of the power amplification circuit.

[0011] Preferably, the radio frequency power amplifier further includes a fourth resistor, a first end of the fourth resistor is respectively connected to the emitter of the second triode and the first end of the feedback circuit, and a second end of the fourth resistor is connected to the input end of the power amplification circuit.

[0012] Preferably, the feedback circuit includes a third capacitor and a fifth resistor; the first end of the fifth resistor serves as the first end of the feedback circuit, the second end of the fifth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor serves as the second end of the feedback circuit.

[0013] Preferably, the RF power amplifier further includes a fourth capacitor, the first end of the fourth capacitor is used to access the RF signal, and the second end of the fourth capacitor is connected to the input end of the power amplification circuit.

[0014] Preferably, the RF power amplifier further includes a first inductor; the first end of the first inductor is used to be connected to an external third power supply, and the second end of the first inductor is respectively connected to the second end of the feedback circuit and the output end of the power amplification circuit.

[0015] Preferably, the power amplification circuit includes a third triode, the base of the third triode serves as the input end of the power amplification circuit, the collector of the third triode serves as the output end of the power amplification circuit, and the emitter of the third triode is grounded.

[0016] Compared with the related art, in the embodiments of the present invention, by using the first bias circuit and the second bias circuit to respectively provide bias current for the power amplification circuit, the gain and linear performance of the PA are stabilized at high and low temperatures; the second end of the first resistor of the first bias circuit is respectively connected to the first end of the first voltage dividing circuit and the base of the first triode, the second end of the first voltage dividing circuit is grounded, and the emitter of the first triode is connected to the input end of the power amplification circuit; the second end of the second resistor of the second bias circuit is respectively connected to the first end of the second voltage dividing circuit and the base of the second triode, the collector of the first triode is connected to the collector of the second triode and jointly connected to the second power supply, the second end of the second voltage dividing circuit is grounded, and the emitter of the second triode is respectively connected to the first end of the feedback circuit and the input end of the power amplification circuit; through the temperature change characteristics of the first voltage dividing circuit and the second voltage dividing circuit, the node voltage at the first end of the first voltage dividing circuit also decreases as the temperature rises, and at the same time, the node voltage at the first end of the second voltage dividing circuit also decreases as the temperature rises, so that the voltage changes of the two node voltages can compensate each other with the temperature change, so that the voltage drop across the second resistor remains unchanged, and further the bias current remains unchanged, reducing the changes in the linear performance and gain of the power amplifier as the temperature rises; at low temperatures, similarly, the changes in the linear performance and gain of the power amplifier as the temperature decreases can also be reduced. In addition, a simplified circuit layout and a smaller chip area occupation can be achieved. Description of the Drawings

[0017] The present invention will be described in detail below with reference to the accompanying drawings. Through the detailed description made in conjunction with the following drawings, the above or other aspects of the present invention will become clearer and easier to understand. In the drawings: Figure 1 is the circuit diagram of the radio frequency power amplifier provided by an embodiment of the present invention.

[0018] Among them, 100 is the radio frequency power amplifier, 1 is the power amplification circuit, 2 is the first bias circuit, 21 is the first voltage division circuit, 3 is the second bias circuit, 31 is the second voltage division circuit, and 4 is the feedback circuit. Specific embodiments

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the description of the present application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0020] Referring to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to Figure 1As shown in the figure, an embodiment of the present invention provides a radio frequency power amplifier 100, and the radio frequency power amplifier 100 includes a power amplification circuit 1, a first bias circuit 2, a second bias circuit 3 (power boost bias circuit), and a (power boost) feedback circuit 4. The input unit of the power amplification circuit 1 is used to access a radio frequency signal, and the radio frequency signal is output through a signal input terminal (Input). The output terminal of the power amplification circuit 1 is used to output the radio frequency signal after amplification, and the radio frequency signal is output through a signal output terminal (Output). The first bias circuit 2 and the second bias circuit 3 are respectively used to provide a bias current for the power amplification circuit 1. The first end of the feedback circuit 4 is connected to the output terminal of the second bias circuit 3, and the second end of the feedback circuit 4 is connected to the output terminal of the power amplification circuit 1. The feedback circuit 4 is used to receive the signal output by the power amplification circuit 1 and feedback it to the second bias circuit 3. By inputting a radio frequency signal to the power amplification circuit 1 for signal amplification, and outputting it through the output terminal of the power amplification circuit 1. The first bias circuit 2 and the second bias circuit 3 respectively provide a bias current for the input terminal of the power amplification circuit 1, so that the bias current remains unchanged, reducing the changes in the linear performance and gain of the power amplifier caused by temperature changes, and having good temperature stability.

[0023] The first bias circuit 2 includes a first resistor R1, a first voltage dividing circuit 21, and a first triode BJT1. The first end of the first resistor R1 is used to connect to an external first power source SRC1, the second end of the first resistor R1 is respectively connected to the first end of the first voltage dividing circuit 21 and the base of the first triode BJT1, and the second end of the first voltage dividing circuit 21 is grounded. The emitter of the first triode BJT1 is connected to the input terminal of the power amplification circuit 1, and the collector of the first triode is used to connect to an external second power source SRC2. The first power source SRC1 is used to supply a DC power source for the first resistor R1.

[0024] The second bias circuit 3 includes a second resistor R2, a second voltage dividing circuit 31, and a second triode BJT2. The first end of the second resistor R2 is connected to the second end of the first resistor R1, the second end of the second resistor R2 is respectively connected to the first end of the second voltage dividing circuit 31 and the base of the second triode BJT2, the collector of the second triode BJT2 is connected to the second power source SRC2, and the second end of the second voltage dividing circuit 31 is grounded. The emitter of the second triode BJT2 is respectively connected to the first end of the feedback circuit 4 and the input terminal of the power amplification circuit 1. The second power source SRC2 is used to supply a DC power source for the collector of the first triode BJT1 and the collector of the second triode BJT2.

[0025] Specifically, the first resistor R1 and the second resistor R2 are voltage-current conversion resistors. Since the first bipolar junction transistor BJT1 and the second bipolar junction transistor BJT2 are current-driven devices, the first resistor R1 and the second resistor R2 are used to provide bias currents for the input terminals of the power amplifier circuit 1 respectively. The DC power supply provided by the first power supply SRC1 and the fixed voltage of the node P1 are respectively converted into the base currents of the first bipolar junction transistor BJT1 and the second bipolar junction transistor BJT2 through the first resistor R1 and the second resistor R2, so as to realize the current bias of the power amplifier circuit 1. The DC power supply of the first bias circuit 2 is provided by the node P1. The voltage of the node P1 at room temperature is fixed, about 2.5V, and does not change with the change of the voltage of the first power supply SRC1. Therefore, the supply voltage of the first bias circuit 2 is also very stable. By adjusting the resistance value of the second resistor R2, the bias current intensity of the circuit can be conveniently adjusted.

[0026] According to the diode temperature change characteristics of the first voltage dividing circuit 21 and the second voltage dividing circuit 31, the voltage of the node P1 at the first end of the first voltage dividing circuit 21 decreases as the temperature rises. At the same time, the voltage of the node P2 at the first end of the second voltage dividing circuit 31 also decreases as the temperature rises, so that the voltage changes of the two node voltages can compensate each other with the temperature change, so that the voltage drop across the second resistor R2 remains unchanged. Further, the bias current of the second bias circuit 3 is kept constant, reducing the changes in the power amplifier linear performance and gain caused by the temperature rise. At low temperatures, similarly, the changes in the power amplifier linear performance and gain caused by the temperature drop can also be reduced. In addition, this solution reduces the number of DC power supplies, thus simplifying the circuit layout and reducing the chip area occupied.

[0027] In this embodiment, the first voltage dividing circuit 21 includes a first diode D1 and a second diode D2. The positive electrode of the first diode D1 serves as the first end of the first voltage dividing circuit 21. The negative electrode of the first diode D1 is connected to the positive electrode of the second diode D2. The negative electrode of the second diode D2 serves as the second end of the first voltage dividing circuit 21. Through the temperature change characteristics of the first diode D1 and the second diode D2, the PA gain change and linear performance change caused by temperature change can be reduced. The negative electrode of the second diode D2 is connected to the ground terminal. The connection node P1 between the first power supply SRC1 and the first diode D1 is connected to the base of the first bipolar junction transistor BJT1. The input current of the first power supply SRC1 is input to the base of the first bipolar junction transistor BJT1 after being subjected to voltage division by the first diode D1 and the second diode D2, so that the first bipolar junction transistor BJT1 forms a bias current and outputs it from its emitter.

[0028] The second voltage dividing circuit 31 includes a third diode D3 and a fourth diode D4. The positive electrode of the third diode D3 serves as the first end of the second voltage dividing circuit 31, the negative electrode of the third diode D3 is connected to the positive electrode of the fourth diode D4, and the negative electrode of the fourth diode D4 serves as the second end of the second voltage dividing circuit 31. By the temperature change characteristics of the third diode D3 and the fourth diode D4, the PA gain change and linear performance change caused by temperature change can be reduced. The negative electrode of the fourth diode D4 is connected to the ground terminal, and the connection node P1 between the first power source SRC1 and the third diode D3 is connected to the base of the second triode BJT2. The input current of the first power source SRC1 is input to the base of the second triode BJT2 after being subjected to voltage division processing formed by the third diode D3 and the fourth diode D4, so that the second triode BJT2 forms a bias current and outputs from its emitter.

[0029] In this embodiment, the radio frequency power amplifier 100 further includes a first capacitor C1. The first end of the first capacitor C1 is connected to the base of the first triode BJT1, and the second end of the first capacitor C1 is grounded. The first capacitor C1 is a bias gain expansion capacitor. Connecting the first capacitor C1 to the base of the first triode BJT1 can, to a certain extent, optimize the linearity of the AM-AM of the power amplifier.

[0030] In this embodiment, the radio frequency power amplifier 100 further includes a second capacitor C2. The first end of the second capacitor C2 is connected to the base of the second triode BJT2, and the second end of the second capacitor C2 is grounded. The second capacitor C2 is a bias gain expansion capacitor. Connecting the second capacitor C2 to the base of the second triode BJT2 can, to a certain extent, optimize the linearity of the AM-AM of the power amplifier.

[0031] In this embodiment, the radio frequency power amplifier 100 further includes a third resistor R3. The first end of the third resistor R3 is connected to the emitter of the first triode BJT1, and the second end of the third resistor R3 is connected to the input end of the power amplification circuit 1. By connecting the third resistor R3 to the emitter of the first triode BJT1, the bias current output by the first triode BJT1 is made stable.

[0032] In this embodiment, the radio frequency power amplifier 100 further includes a fourth resistor R4. The first end of the fourth resistor R4 is respectively connected to the emitter of the second triode BJT2 and the first end of the feedback circuit 4, and the second end of the fourth resistor R4 is connected to the input end of the power amplification circuit 1. By connecting the fourth resistor R4 to the emitter of the second triode BJT2, the bias current output by the second triode BJT2 is made stable.

[0033] In this embodiment, the feedback circuit 4 includes a third capacitor C3 and a fifth resistor R5. The first end of the fifth resistor R5 serves as the first end of the feedback circuit 4, the second end of the fifth resistor R5 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 serves as the second end of the feedback circuit 4. The output signal of the power amplifier circuit 1 can be fed back to the second bias circuit 3 through the third capacitor C3 and the fifth resistor R5, so that when the power amplifier circuit 1 outputs a large signal, the collapsed AM-AM of the power amplifier itself becomes flatter after being linearly biased by the first bias circuit 2 and the second bias circuit 3.

[0034] In this embodiment, the RF power amplifier 100 further includes a fourth capacitor C4, a first end of the fourth capacitor C4 is used to access the RF signal, and a second end of the fourth capacitor C4 is connected to the input end of the power amplifier circuit 1. The fourth capacitor C4 is used to implement an input matching function.

[0035] In this embodiment, the RF power amplifier 100 further includes a first inductor L1, a first end of the first inductor L1 is used to connect to an external third power supply SRC3, and a second end of the first inductor L1 is respectively connected to a second end of the feedback circuit 4 and an output end of the power amplifier circuit 1. The third power supply SRC3 provides power supply to the output end of the power amplifier circuit 1, so that the power amplifier circuit 1 can operate normally.

[0036] In this embodiment, the power amplifier circuit 1 includes a third transistor BJT3, the base of the third transistor BJT3 serves as the input end of the power amplifier circuit 1, the collector of the third transistor BJT3 serves as the output end of the power amplifier circuit 1, and the emitter of the third transistor BJT3 is grounded. The third transistor BJT3 is used to power amplify the RF input signal.

[0037] In this embodiment, the first transistor BJT1, the second transistor BJT2 and the third transistor BJT3 may also be heterojunction bipolar transistors (HBT) transistors, metal oxide semiconductor (MOS) transistors, etc. The principles and effects produced are the same and will not be described again.

[0038] It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than to limit the scope of the present invention. Those skilled in the art should understand that any modification or equivalent substitution of the present invention without departing from the spirit and scope of the present invention should be included within the scope of the present invention. In addition, unless otherwise indicated by the context, words appearing in the singular include the plural form, and vice versa. In addition, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A radio frequency power amplifier, characterized in that: The radio frequency power amplifier comprises a power amplifier circuit, a first bias circuit, a second bias circuit and a feedback circuit; the input unit of the power amplifier circuit is used to receive a radio frequency signal, and the output end of the power amplifier circuit is used to amplify the radio frequency signal and then output it; the first bias circuit and the second bias circuit are respectively used to provide bias current for the power amplifier circuit; The first end of the feedback circuit is connected to the output end of the second bias circuit, the second end of the feedback circuit is connected to the output end of the power amplifier circuit, and the feedback circuit is used to receive the signal output by the power amplifier circuit and feed it back to the second bias circuit; The first bias circuit includes a first resistor, a first voltage divider circuit and a first transistor; the first end of the first resistor is used to connect to an external first power supply, the second end of the first resistor is respectively connected to the first end of the first voltage divider circuit and the base of the first transistor, the second end of the first voltage divider circuit is grounded, the emitter of the first transistor is connected to the input end of the power amplifier circuit, and the collector of the first transistor is used to connect to an external second power supply; The second bias circuit includes a second resistor, a second voltage divider circuit and a second transistor; the first end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is respectively connected to the first end of the second voltage divider circuit and the base of the second transistor, the collector of the second transistor is used to be connected to the second power supply, the second end of the second voltage divider circuit is grounded, and the emitter of the second transistor is respectively connected to the first end of the feedback circuit and the input end of the power amplifier circuit.

2. The radio frequency power amplifier according to claim 1, characterized in that: The first voltage divider circuit includes a first diode and a second diode, the anode of the first diode serves as a first end of the first voltage divider circuit, the cathode of the first diode is connected to the anode of the second diode, and the cathode of the second diode serves as a second end of the first voltage divider circuit; The second voltage divider circuit includes a third diode and a fourth diode, the anode of the third diode serves as the first end of the second voltage divider circuit, the cathode of the third diode is connected to the anode of the fourth diode, and the cathode of the fourth diode serves as the second end of the second voltage divider circuit.

3. The radio frequency power amplifier according to claim 1, characterized in that: The radio frequency power amplifier further includes a first capacitor, a first end of the first capacitor is connected to the base of the first transistor, and a second end of the first capacitor is grounded.

4. The radio frequency power amplifier according to claim 1, characterized in that: The radio frequency power amplifier further includes a second capacitor, a first end of the second capacitor is connected to the base of the second transistor, and a second end of the second capacitor is grounded.

5. The radio frequency power amplifier according to claim 1, characterized in that: The RF power amplifier further includes a third resistor, a first end of the third resistor is connected to the emitter of the first transistor, and a second end of the third resistor is connected to the input end of the power amplifier circuit.

6. The radio frequency power amplifier according to claim 1, characterized in that: The RF power amplifier also includes a fourth resistor, a first end of the fourth resistor is respectively connected to the emitter of the second transistor and the first end of the feedback circuit, and a second end of the fourth resistor is connected to the input end of the power amplifier circuit.

7. The radio frequency power amplifier according to claim 1, characterized in that: The feedback circuit includes a third capacitor and a fifth resistor; the first end of the fifth resistor serves as the first end of the feedback circuit, the second end of the fifth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor serves as the second end of the feedback circuit.

8. The radio frequency power amplifier according to claim 1, characterized in that: The RF power amplifier further includes a fourth capacitor, a first end of the fourth capacitor is used to access the RF signal, and a second end of the fourth capacitor is connected to an input end of the power amplifier circuit.

9. The radio frequency power amplifier according to claim 1, characterized in that: The RF power amplifier also includes a first inductor; a first end of the first inductor is used to connect to an external third power supply, and a second end of the first inductor is respectively connected to a second end of the feedback circuit and an output end of the power amplifier circuit.

10. The radio frequency power amplifier according to claim 1, characterized in that: The power amplifier circuit includes a third transistor, the base of the third transistor serves as the input end of the power amplifier circuit, the collector of the third transistor serves as the output end of the power amplifier circuit, and the emitter of the third transistor is grounded.

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