Power amplifier circuit

Abstract

The present invention provides a power amplifier circuit, which includes a signal input terminal, an input matching network, a first transistor, an inter-stage matching network, a second transistor, an output matching network and a signal output terminal connected in sequence, the input terminal of the second resonant circuit is connected to the first output terminal of the second bias circuit; the emitter of the second transistor is grounded, and the collector of the second transistor is respectively connected in series with a second inductor to a second power supply voltage and an input terminal connected to the output matching network; the power amplifier circuit also includes a current limiting circuit, the first terminal of the current limiting circuit is connected to the input terminal of the inter-stage matching network, the second terminal of the current limiting circuit is connected to the input terminal of the second resonant circuit, and the third terminal of the current limiting circuit is connected to the second output terminal of the second bias circuit. The power amplifier circuit of the present invention can improve gain and efficiency and has high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a power amplifier circuit. Background Art

[0002] As humans enter the information age, wireless communication technology has developed rapidly. From mobile phones, wireless LANs, Bluetooth, etc., it has become an indispensable part of social life and development. The progress of wireless communication technology is inseparable from the development of radio frequency circuits. With the development and evolution of modern wireless communication systems, the requirements for data transmission rate and capacity are getting higher and higher.

[0003] At present, in the power amplifier of today's portable mobile communication devices, the distance between the base station and the mobile device will increase or decrease the output power of the power amplifier. Therefore, it is necessary to have a technology to suppress linear distortion in the process of increasing and decreasing the output power of the power amplifier, and reduce the power consumption to a certain range to improve the overall efficiency. In the design of simple linear RF / microwave amplifiers, S parameter matching is generally used to maximize the gain. At the same time, it is also hoped that the gain and power consumption in low power mode are as low as possible.

[0004] However, the gain and efficiency improvement effects of the above power amplifier are poor, the reliability is low, and the application scope is small. Summary of the invention

[0005] In view of the above deficiencies in the prior art, the present invention proposes a power amplifier circuit to solve the problems of poor gain and efficiency improvement effects, low reliability and small application range of the prior power amplifier circuit.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An embodiment of the present invention provides a power amplifier circuit, comprising a signal input terminal, an input matching network, a first transistor, an inter-stage matching network, a second transistor, an output matching network and a signal output terminal connected in sequence, the power amplifier circuit also comprising a first resonant circuit, a second resonant circuit, a first capacitor, a second capacitor, a first bias circuit for providing a bias voltage for the first transistor, and a second bias circuit for providing a bias voltage for the second transistor;

[0008] The first end of the first capacitor is respectively connected to the output end of the input matching network and the first output end of the first resonant circuit, the second end of the first capacitor is respectively connected to the base of the first transistor and the second output end of the first resonant circuit, the input end of the first resonant circuit is connected to the output end of the first bias circuit; the emitter of the first transistor is grounded, the collector of the first transistor is connected in series with the first inductor for connecting to the first power supply voltage, and the collector of the first transistor is also connected to the input end of the inter-stage matching network;

[0009] The first end of the second capacitor is respectively connected to the output end of the inter-stage matching network and the first output end of the second resonant circuit, the second end of the second capacitor is respectively connected to the base of the second transistor and the second output end of the second resonant circuit, and the input end of the second resonant circuit is connected to the first output end of the second bias circuit; the emitter of the second transistor is grounded, the collector of the second transistor is connected in series with the second inductor for connecting to the second power supply voltage, and the collector of the second transistor is also connected to the input end of the output matching network;

[0010] The power amplifier circuit also includes a current limiting circuit, a first end of the current limiting circuit is connected to the input end of the inter-stage matching network, a second end of the current limiting circuit is connected to the input end of the second resonant circuit, and a third end of the current limiting circuit is connected to the second output end of the second bias circuit.

[0011] Preferably, the power amplifier circuit further includes a third transistor, a third capacitor, a third resonant circuit and a third bias circuit;

[0012] The first end of the third capacitor is respectively connected to the output end of the input matching network and the first output end of the third resonant circuit, the second end of the third capacitor is respectively connected to the base of the third transistor and the second output end of the third resonant circuit, the input end of the third resonant circuit is connected to the output end of the third bias circuit; the collector of the third transistor is connected to the input end of the inter-stage matching network, and the emitter of the third transistor is grounded.

[0013] Preferably, the power amplifier circuit further includes a fourth transistor, a fourth capacitor, a fourth resonant circuit and a fourth bias circuit;

[0014] The first end of the fourth capacitor is respectively connected to the output end of the inter-stage matching network and the first output end of the fourth resonant circuit, the second end of the fourth capacitor is respectively connected to the base of the fourth transistor and the second output end of the fourth resonant circuit, the input end of the fourth resonant circuit is connected to the output end of the fourth bias circuit; the collector of the fourth transistor is connected to the input end of the output matching network, and the emitter of the fourth transistor is grounded.

[0015] Preferably, the first resonant circuit includes a fifth capacitor, a third inductor and a first resistor, the first end of the fifth capacitor serves as the first output end of the first resonant circuit, the second end of the fifth capacitor is connected to the first end of the third inductor, the first end of the first resistor serves as the second output end of the first resonant circuit, and the second end of the third inductor and the second end of the first resistor are connected and serve together as the input end of the first resonant circuit.

[0016] Preferably, the second resonant circuit includes a sixth capacitor, a fourth inductor and a second resistor, the first end of the sixth capacitor serves as the first output end of the second resonant circuit, the second end of the sixth capacitor is connected to the first end of the fourth inductor, the first end of the second resistor serves as the second output end of the second resonant circuit, and the second end of the fourth inductor and the second end of the second resistor are connected together as the input end of the second resonant circuit.

[0017] Preferably, the third resonant circuit includes a seventh capacitor, a fifth inductor and a third resistor, the first end of the seventh capacitor serves as the first output end of the third resonant circuit, the second end of the seventh capacitor is connected to the first end of the fifth inductor, the first end of the third resistor serves as the second output end of the third resonant circuit, and the second end of the fifth inductor and the second end of the third resistor are connected together as the input end of the third resonant circuit.

[0018] Preferably, the fourth resonant circuit includes an eighth capacitor, a sixth inductor and a fourth resistor, the first end of the eighth capacitor serves as the first output end of the fourth resonant circuit, the second end of the eighth capacitor is connected to the first end of the sixth inductor, the first end of the fourth resistor serves as the second output end of the fourth resonant circuit, and the second end of the sixth inductor and the second end of the fourth resistor are connected together as the input end of the fourth resonant circuit.

[0019] Preferably, the first bias circuit, the second bias circuit, the third bias circuit and the fourth bias circuit have the same structure;

[0020] The second bias circuit includes a fifth transistor, a sixth transistor, a seventh transistor, a fifth resistor and a ninth capacitor;

[0021] The first end of the fifth resistor is used as the input end of the second bias circuit to connect to the bias voltage, and the second end of the fifth resistor is connected to the collector of the sixth transistor;

[0022] The collector of the fifth transistor is used to connect to a bias power supply, the base of the fifth transistor is respectively connected to the collector of the sixth transistor and the first end of the ninth capacitor, and the emitter of the fifth transistor serves as the first output end of the second bias circuit;

[0023] The base of the sixth transistor is connected to the collector of the sixth transistor, and the emitter of the sixth transistor is connected to the collector of the seventh transistor;

[0024] The base of the seventh transistor is connected to the collector of the seventh transistor, and the emitter of the seventh transistor is connected to the second end of the ninth capacitor and is grounded together.

[0025] Preferably, the current limiting circuit includes a sixth resistor, a seventh resistor and an eighth transistor; the first end of the seventh resistor serves as the first end of the current limiting circuit, the second end of the seventh resistor is connected to the collector of the eighth transistor, the emitter of the eighth transistor serves as the second end of the current limiting circuit, the base of the eighth transistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor serves as the third end of the current limiting circuit.

[0026] Compared with the related art, in the embodiment of the present invention, the first end of the first capacitor is connected to the output end of the input matching network and the first output end of the first resonant circuit respectively, the second end of the first capacitor is connected to the base of the first transistor and the second output end of the first resonant circuit respectively, and the input end of the first resonant circuit is connected to the output end of the first bias circuit; the emitter of the first transistor is grounded, the collector of the first transistor is connected in series with the first inductor for connecting to the first power supply voltage, and the collector of the first transistor is simultaneously connected to the input end of the interstage matching network; the first end of the second capacitor is connected to the output end of the interstage matching network and the first output end of the second resonant circuit respectively, the second end of the second capacitor is connected to the base of the second transistor and the second output end of the second resonant circuit respectively, and the input end of the second resonant circuit is connected to the output end of the second bias circuit; the emitter of the second transistor is grounded, the collector of the second transistor is connected in series with the second inductor for connecting to the second power supply voltage, and the collector of the second transistor is simultaneously connected to the input end of the output matching network. In this way, the first transistor and the second transistor are resonated respectively by the first resonant circuit and the second resonant circuit, so that their resonant frequencies can be changed, thereby changing the AC component of the bias current, thereby more accurately suppressing the deterioration of gain compression and distortion characteristics. At the same time, in the process of designing the power amplifier (PA), technology to suppress the deterioration of linear distortion is added, and different working states of the first transistor and the second transistor are used to adjust the gain of the amplifier in high power mode and low power mode and improve the power added efficiency in low power mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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:

[0028] Figure 1 is a circuit diagram of a power amplifier circuit in an embodiment of the present invention;

[0029] Figure 2 is a circuit diagram of a power amplifier circuit in an embodiment of the present invention;

[0030] Figure 3 A data graph showing efficiency and current in a low power mode of an existing amplifier circuit;

[0031] Figure 4 for Figure 2 Figure 2 shows the efficiency and current in low power mode.

[0032] Among them, 100, power amplifier circuit, 1, signal input end, 2, input matching network, 3, inter-stage matching network, 4, output matching network, 5, signal output end, 6, first resonant circuit, 7, second resonant circuit, 8, third resonant circuit, 9, fourth resonant circuit, 10, first bias circuit, 11, second bias circuit, 12, third bias circuit, 13, fourth bias circuit, 14, current limiting circuit. DETAILED DESCRIPTION

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] See also Figure 1-4 As shown, an embodiment of the present invention provides a power amplifier circuit 100, which includes a signal input terminal 1 (RFIN), an input matching network 2, a first transistor Q1, an inter-stage matching network 3, a second transistor Q2, an output matching network 4 and a signal output terminal 5 (RFOUT) connected in sequence, and the power amplifier circuit 100 also includes a first resonant circuit 6, a second resonant circuit 7, a first capacitor C1, a second capacitor C2, a first bias circuit 10 for providing a bias voltage for the first transistor Q1, and a second bias circuit 11 for providing a bias voltage for the second transistor Q2.

[0037] The first end of the first capacitor C1 is respectively connected to the output end of the input matching network 2 and the first output end of the first resonant circuit 6, the second end of the first capacitor C1 is respectively connected to the base of the first transistor Q1 and the second output end of the first resonant circuit 6, the input end of the first resonant circuit 6 is connected to the first output end of the first bias circuit 10, the emitter of the first transistor Q1 is grounded, the collector of the first transistor Q1 is connected to the first power supply voltage VCC1 via a first series inductor L1, and the collector of the first transistor Q1 is connected to the input end of the inter-stage matching network 3.

[0038] The first end of the second capacitor C2 is respectively connected to the output end of the inter-stage matching network 3 and the first output end of the second resonant circuit 7, the second end of the second capacitor C2 is respectively connected to the base of the second transistor Q2 and the second output end of the second resonant circuit 7, the input end of the second resonant circuit 7 is connected to the output end of the second bias circuit 11; the emitter of the second transistor Q2 is grounded, the collector of the second transistor Q2 is connected to the second power supply voltage VCC2 via a second inductor L2 in series, and the collector of the second transistor Q2 is also connected to the input end of the output matching network 4.

[0039] The first capacitor C1 and the second capacitor C2 play a direct current isolation function. The first inductor L1 and the second inductor L2 are used to prevent the radio frequency signal from leaking to the first power supply voltage VCC1 and the second power supply voltage VCC2 respectively. The first bias circuit 10 and the second bias circuit 11 are used to provide base voltages for the first transistor Q1 and the second transistor Q2 respectively; the first transistor Q1 and the second transistor Q2 are used to amplify the radio frequency signal.

[0040] In this way, the first transistor Q1 and the second transistor Q2 are resonated respectively by the first resonant circuit 6 and the second resonant circuit 7, so that the resonant frequency can be changed, thereby changing the AC component of the bias current, thereby more accurately suppressing the deterioration of gain compression and distortion characteristics. At the same time, in the process of designing the power amplifier (PA), the technology of suppressing the deterioration of linear distortion and the use of different working states of the first transistor Q1 and the second transistor Q2 are added to adjust the gain of the high power mode and the low power mode of the amplifier and improve the power added efficiency in the low power mode.

[0041] In this embodiment, the power amplifier circuit 100 further includes a current limiting circuit 14, a first end of the current limiting circuit 14 is connected to the input end of the inter-stage matching network 3, a second end of the current limiting circuit 14 is connected to the input end of the second resonant circuit 7, and a third end of the current limiting circuit 14 is connected to the base of the fifth transistor. When the second bias circuit 11 provides a bias voltage to the second transistor Q2, the current limiting circuit 14 can extract a part of the base circuit output by the second bias circuit 11, so that the collector current of the second transistor Q2 will also be reduced accordingly, thereby achieving the effect of improving efficiency.

[0042] In this embodiment, the power amplifier circuit 100 further includes a third transistor Q3, a third capacitor C3, a third resonant circuit 8 and a third bias circuit 12. The first end of the third capacitor C3 is respectively connected to the output end of the input matching network 2 and the first output end of the third resonant circuit 8, the second end of the third capacitor C3 is respectively connected to the base of the third transistor Q3 and the second output end of the third resonant circuit 8, the input end of the third resonant circuit 8 is connected to the output end of the third bias circuit 12, the collector of the third transistor Q3 is connected to the input end of the inter-stage matching network 3, and the emitter of the third transistor Q3 is grounded.

[0043] In this embodiment, the power amplifier circuit 100 also includes a fourth transistor Q4, a fourth capacitor C4, a fourth resonant circuit 9 and a fourth bias circuit 13; the first end of the fourth capacitor C4 is respectively connected to the output end of the inter-stage matching network 3 and the first output end of the fourth resonant circuit 9, the second end of the fourth capacitor C4 is respectively connected to the base of the fourth transistor Q4 and the second output end of the fourth resonant circuit 9, the input end of the fourth resonant circuit 9 is connected to the output end of the fourth bias circuit 13, the collector of the fourth transistor Q4 is connected to the input end of the output matching network 4, and the emitter of the fourth transistor Q4 is grounded.

[0044] Among them, the output matching network 4 is used to perform impedance matching so that the power transmission loss between the input to the first transistor Q1 and the third transistor Q3 is minimized; the inter-stage matching is to perform impedance matching between the first transistor Q1 and the third transistor Q3 of the previous stage and the second transistor Q2 and the fourth transistor Q4 of the next stage, so that more power output from the previous stage can reach the next stage; the output matching is the impedance matching between the second transistor Q2 and the fourth transistor Q4 to the output terminal, so that the output power is maximized.

[0045] Specifically, when the power amplifier circuit works in the low power mode, the first bias circuit 10, the second bias circuit 11, the third bias circuit 12 and the fourth bias circuit 13 work in different states respectively. The first bias circuit 10 does not provide a voltage to the first transistor Q1, and the third bias circuit 12 provides a bias voltage to the third transistor Q3; the second bias circuit 11 does not provide a voltage to the second transistor Q2, and the fourth bias circuit 13 provides a bias voltage to the fourth transistor Q4. In this way, only the third transistor Q3 and the fourth transistor Q4 work, so that the gain is greatly reduced in this mode, and the overall efficiency is also improved.

[0046] When the power amplifier circuit operates in the high power mode, the first bias circuit 10, the second bias circuit 11, the third bias circuit 12 and the fourth bias circuit 13 respectively operate in different states. The first bias circuit 10 provides a bias voltage to the first transistor Q1, the second bias circuit 11 provides a voltage to the second transistor Q2, and the third bias circuit 12 provides a bias voltage to the third transistor Q3; the fourth bias circuit 13 provides a bias voltage to the fourth transistor Q4, so that the four transistors are all working, so that the amplifier can achieve the highest gain.

[0047] Of course, the above four transistors Q1-Q4 can be combined in low power mode or high power mode to meet the need of no gain. For example, the first transistor Q1 works, the second transistor Q2 works, the third transistor Q3 does not work, and the fourth transistor Q4 does not work, which can also achieve the purpose of high gain. Optionally, the first transistor Q1 does not work, the second transistor Q2 works, the third transistor Q3 works, and the fourth transistor Q4 does not work, which can also achieve the purpose of low gain and efficiency compromise, and so on.

[0048] The transistor is composed of bipolar transistors such as heterojunction bipolar transistors (HBT). It should be noted that the transistor can also be composed of other transistors such as field effect transistors (MOSFET). In this case, the base, collector and emitter can be replaced by the gate, drain and source respectively.

[0049] The first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4 can be one transistor or several transistors connected in parallel. There is no strict limitation here and it is completely determined by the transistor area after design simulation.

[0050] In this embodiment, the first resonant circuit 6 includes a fifth capacitor C5, a third inductor L3 and a first resistor R1, the first end of the fifth capacitor C5 serves as the first output end of the first resonant circuit 6, the second end of the fifth capacitor C5 is connected to the first end of the third inductor L3, the first end of the first resistor R1 serves as the second output end of the first resonant circuit 6, and the second end of the third inductor L3 and the second end of the first resistor R1 are connected and serve together as the input end of the first resonant circuit 6.

[0051] In this embodiment, the second resonant circuit 7 includes a sixth capacitor C6, a fourth inductor L4 and a second resistor R2, the first end of the sixth capacitor C6 serves as the first output end of the second resonant circuit 7, the second end of the sixth capacitor C6 is connected to the first end of the fourth inductor L4, the first end of the second resistor R2 serves as the second output end of the second resonant circuit 7, and the second end of the fourth inductor L4 and the second end of the second resistor R2 are connected together as the input end of the second resonant circuit 7.

[0052] In this embodiment, the third resonant circuit 8 includes a seventh capacitor C7, a fifth inductor L5 and a third resistor R3, the first end of the seventh capacitor C7 serves as the first output end of the third resonant circuit 8, the second end of the seventh capacitor C7 is connected to the first end of the fifth inductor L5, the first end of the third resistor R3 serves as the second output end of the third resonant circuit 8, and the second end of the fifth inductor L5 and the second end of the third resistor R3 are connected together as the input end of the third resonant circuit 8.

[0053] In this embodiment, the fourth resonant circuit 9 includes an eighth capacitor C8, a sixth inductor L6 and a fourth resistor R4, the first end of the eighth capacitor C8 serves as the first output end of the fourth resonant circuit 9, the second end of the eighth capacitor C8 is connected to the first end of the sixth inductor L6, the first end of the fourth resistor R4 serves as the second output end of the fourth resonant circuit 9, and the second end of the sixth inductor L6 and the second end of the fourth resistor R4 are connected together as the input end of the fourth resonant circuit 9.

[0054] Specifically, the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7 and the eighth capacitor C8 are regarded as open circuit structures relative to the DC component, and are regarded as short circuit conduction relative to the AC component. Thus, the first bias circuit 10, the second bias circuit 11, the third bias circuit 12 and the fourth bias circuit 13 can flow to the base of the first transistor Q1, the base of the second transistor Q2, the base of the third transistor Q3 and the base of the fourth transistor Q4 respectively, and the AC component of the bias current of the base of the first transistor Q1, the base of the second transistor Q2, the base of the third transistor Q3 and the base of the fourth transistor Q4 efficiently flows to the base of the transistor through the first capacitor C1 and the fifth capacitor C5, the second capacitor C2 and the sixth capacitor C6, the third capacitor C3 and the seventh capacitor C7, and the fourth capacitor C4 and the eighth capacitor C8 respectively. The gain compression of the amplifier can be effectively suppressed, and the deterioration of the distortion characteristics of the amplifier can be suppressed.

[0055] Specifically, by appropriately connecting the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7 and the eighth capacitor C8 in series with the third inductor L3, the fourth inductor L4, the fifth inductor L5 and the sixth inductor L6 to form a resonant circuit, the resonant frequency can be changed, thereby changing the AC component of the bias current, thereby more accurately suppressing the deterioration of gain compression and distortion characteristics.

[0056] Among them, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are respectively used to perform ballast functions on the first resonant circuit 6, the second resonant circuit 7, the third resonant circuit 8 and the fourth resonant circuit 9, so as to improve the thermal stability of the corresponding first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4.

[0057] In this embodiment, the first bias circuit 10 , the second bias circuit 11 , the third bias circuit 12 , and the fourth bias circuit 13 have the same structure.

[0058] The second bias circuit 11 includes a fifth transistor Q11, a sixth transistor Q12, a seventh transistor Q13, a fifth resistor R7 and a ninth capacitor C11.

[0059] The first end of the fifth resistor R7 is used as the input end of the second bias circuit 11 to connect to the bias voltage Vreg2, and the second end of the fifth resistor R7 is connected to the collector of the sixth transistor Q12.

[0060] The collector of the fifth transistor Q11 is used to connect to the bias power supply VBAT, the base of the fifth transistor Q11 is respectively connected to the collector of the sixth transistor Q12 and the first end of the ninth capacitor, and the emitter of the fifth transistor Q11 serves as the first output end of the second bias circuit 11.

[0061] The base of the sixth transistor Q12 is connected to the collector of the sixth transistor Q12 , and the emitter of the sixth transistor Q12 is connected to the collector of the seventh transistor Q13 .

[0062] The base of the seventh transistor Q13 is connected to the collector of the seventh transistor Q13 , and the emitter of the seventh transistor Q13 is connected to the second end of the ninth capacitor C11 and is grounded together.

[0063] In this embodiment, the first bias circuit 10 includes a resistor R5 , a transistor Q5 , a transistor Q6 , a transistor Q7 and a capacitor C9 .

[0064] In this embodiment, the third bias circuit 12 includes a resistor R6 , a transistor Q8 , a transistor Q9 , a transistor Q10 , and a capacitor C10 .

[0065] In this embodiment, the fourth bias circuit 13 includes a resistor R8, a transistor Q14, a transistor Q15, a transistor Q17 and a capacitor C12. Since the first bias circuit 10, the second bias circuit 11, the third bias circuit 12 and the fourth bias circuit 13 have the same structure, their circuits are the same as the second bias circuit 11, and the technical effects produced are the same, and they are not described one by one here.

[0066] In this embodiment, the current limiting circuit 14 includes a sixth resistor R9, a seventh resistor R10 and an eighth transistor Q16; the first end of the seventh resistor R10 serves as the first end of the current limiting circuit 14, the second end of the seventh resistor R10 is connected to the collector of the eighth transistor Q16, the emitter of the eighth transistor Q16 serves as the second end of the current limiting circuit 14, the base of the eighth transistor Q16 is connected to the first end of the sixth resistor R9, and the second end of the sixth resistor R9 serves as the third end of the current limiting circuit 14.

[0067] Specifically, one end of the seventh resistor R10 of the current limiting circuit 14 is connected to the collector of the first transistor Q1, and the other end is connected to the collector of Q16; one end of the sixth resistor R9 is connected to the base of Q11, and the other end is connected to the base of the eighth transistor Q16; the emitter of the eighth transistor Q16 is connected to the fourth inductor L4, the second resistor R2, and the emitter of the fifth transistor Q11;

[0068] In most practical use cases, the first power supply voltage VCC1 and the second power supply voltage VCC2 are connected together to the battery, so the first power supply voltage VCC1 and the second power supply voltage VCC2 will change in voltage at the same time; when the voltages of the first power supply voltage VCC1 and the second power supply voltage VCC2 are lower than the base voltage of the second transistor Q2, the voltage of the C node is reduced by the seventh resistor R10 and reaches the collector voltage of the eighth transistor Q16, which is lower than the voltage of the first power supply voltage VCC1. The emitter of the eighth transistor Q16 is connected to the base of the second transistor Q2 through the second resistor R2, so the emitter voltage of the eighth transistor Q16 is greater than the voltage of the second power supply voltage VCC2. voltage, which is greater than the collector voltage of the eighth transistor Q16, that is, the voltage at point E is greater than the voltage at point C. Since the voltage at point B is generated after clamping the sixth transistor Q12 and the seventh transistor Q13, the voltage at point B is higher than the voltage at point E and higher than the voltage at point C. Therefore, the base-collector and base-emitter of the eighth transistor Q16 are forward biased and forward biased, and the voltage at point E is higher than the voltage at point C. Therefore, the current flows from the emitter to the collector, that is, E flows to C. Therefore, when the fifth transistor Q11 provides a bias voltage to the second transistor Q2, a part of the base current will be drawn away by the current limiting circuit 14 at point E. Therefore, the collector current of the second transistor Q2 will also be reduced accordingly, thereby achieving the effect of improving efficiency.

[0069] When the voltages of the first power supply voltage VCC1 and the second power supply voltage VCC2 are higher than the base voltage of the second transistor Q2, the eighth transistor Q16 is in a normal amplification state, and the current at point B is split and given to the base of the fifth transistor Q11 in one direction, and given to the base of the eighth transistor Q16 in another direction after passing through the sixth resistor R9. Therefore, the current after the convergence at point E will be smaller than that of an idle circuit without adding current, and has little effect on the base current of the second transistor Q2 of the overall circuit.

[0070] In this embodiment, Figure 3 There is no increase in the present invention Figure 1 Figure 2. Amplifier circuit with efficiency and current in low power mode. Figure 4 After adding the circuit limiting circuit Figure 2 The data diagram of the efficiency and current of the amplifier circuit in the low power mode is shown; it can be seen that the efficiency of the power amplifier is improved by 2% and the current is reduced by 14mA after adding the current limiting circuit 14, which shows that the current limiting circuit 14 does play an important role.

[0071] 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 power amplifier circuit, comprising a signal input terminal, an input matching network, a first transistor, an inter-stage matching network, a second transistor, an output matching network and a signal output terminal connected in sequence, characterized in that: The power amplifier circuit further includes a first resonant circuit, a second resonant circuit, a first capacitor, a second capacitor, a first bias circuit for providing a bias voltage for the first transistor, and a second bias circuit for providing a bias voltage for the second transistor; The first end of the first capacitor is respectively connected to the output end of the input matching network and the first output end of the first resonant circuit, the second end of the first capacitor is respectively connected to the base of the first transistor and the second output end of the first resonant circuit, the input end of the first resonant circuit is connected to the output end of the first bias circuit; the emitter of the first transistor is grounded, the collector of the first transistor is connected in series with the first inductor for connecting to the first power supply voltage, and the collector of the first transistor is also connected to the input end of the inter-stage matching network; The first end of the second capacitor is respectively connected to the output end of the inter-stage matching network and the first output end of the second resonant circuit, the second end of the second capacitor is respectively connected to the base of the second transistor and the second output end of the second resonant circuit, and the input end of the second resonant circuit is connected to the first output end of the second bias circuit; the emitter of the second transistor is grounded, the collector of the second transistor is connected in series with the second inductor for connecting to the second power supply voltage, and the collector of the second transistor is also connected to the input end of the output matching network; The power amplifier circuit further includes a current limiting circuit, a first end of the current limiting circuit is connected to the input end of the inter-stage matching network, a second end of the current limiting circuit is connected to the input end of the second resonant circuit, and a third end of the current limiting circuit is connected to the second output end of the second bias circuit; The current limiting circuit includes a sixth resistor, a seventh resistor and an eighth transistor; the first end of the seventh resistor serves as the first end of the current limiting circuit, the second end of the seventh resistor is connected to the collector of the eighth transistor, the emitter of the eighth transistor serves as the second end of the current limiting circuit, the base of the eighth transistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor serves as the third end of the current limiting circuit.

2. The power amplifier circuit according to claim 1, characterized in that: The power amplifier circuit further includes a third transistor, a third capacitor, a third resonant circuit and a third bias circuit; The first end of the third capacitor is respectively connected to the output end of the input matching network and the first output end of the third resonant circuit, the second end of the third capacitor is respectively connected to the base of the third transistor and the second output end of the third resonant circuit, the input end of the third resonant circuit is connected to the output end of the third bias circuit; the collector of the third transistor is connected to the input end of the inter-stage matching network, and the emitter of the third transistor is grounded.

3. The power amplifier circuit according to claim 2, characterized in that: The power amplifier circuit further includes a fourth transistor, a fourth capacitor, a fourth resonant circuit and a fourth bias circuit; The first end of the fourth capacitor is respectively connected to the output end of the inter-stage matching network and the first output end of the fourth resonant circuit, the second end of the fourth capacitor is respectively connected to the base of the fourth transistor and the second output end of the fourth resonant circuit, the input end of the fourth resonant circuit is connected to the output end of the fourth bias circuit; the collector of the fourth transistor is connected to the input end of the output matching network, and the emitter of the fourth transistor is grounded.

4. The power amplifier circuit according to claim 1, characterized in that: The first resonant circuit includes a fifth capacitor, a third inductor and a first resistor, the first end of the fifth capacitor serves as the first output end of the first resonant circuit, the second end of the fifth capacitor is connected to the first end of the third inductor, the first end of the first resistor serves as the second output end of the first resonant circuit, and the second end of the third inductor and the second end of the first resistor are connected and serve together as the input end of the first resonant circuit.

5. The power amplifier circuit according to claim 1, characterized in that: The second resonant circuit includes a sixth capacitor, a fourth inductor and a second resistor, the first end of the sixth capacitor serves as the first output end of the second resonant circuit, the second end of the sixth capacitor is connected to the first end of the fourth inductor, the first end of the second resistor serves as the second output end of the second resonant circuit, and the second end of the fourth inductor and the second end of the second resistor are connected together as the input end of the second resonant circuit.

6. The power amplifier circuit according to claim 3, characterized in that: The third resonant circuit includes a seventh capacitor, a fifth inductor and a third resistor, the first end of the seventh capacitor serves as the first output end of the third resonant circuit, the second end of the seventh capacitor is connected to the first end of the fifth inductor, the first end of the third resistor serves as the second output end of the third resonant circuit, and the second end of the fifth inductor and the second end of the third resistor are connected together as the input end of the third resonant circuit.

7. The power amplifier circuit according to claim 3, characterized in that: The fourth resonant circuit includes an eighth capacitor, a sixth inductor and a fourth resistor, the first end of the eighth capacitor serves as the first output end of the fourth resonant circuit, the second end of the eighth capacitor is connected to the first end of the sixth inductor, the first end of the fourth resistor serves as the second output end of the fourth resonant circuit, and the second end of the sixth inductor and the second end of the fourth resistor are connected together as the input end of the fourth resonant circuit.

8. The power amplifier circuit according to claim 3, characterized in that: The first bias circuit, the second bias circuit, the third bias circuit and the fourth bias circuit have the same structure; The second bias circuit includes a fifth transistor, a sixth transistor, a seventh transistor, a fifth resistor and a ninth capacitor; The first end of the fifth resistor is used as the input end of the second bias circuit to connect to the bias voltage, and the second end of the fifth resistor is connected to the collector of the sixth transistor; The collector of the fifth transistor is used to connect to a bias power supply, the base of the fifth transistor is respectively connected to the collector of the sixth transistor and the first end of the ninth capacitor, and the emitter of the fifth transistor serves as the first output end of the second bias circuit; The base of the sixth transistor is connected to the collector of the sixth transistor, and the emitter of the sixth transistor is connected to the collector of the seventh transistor; The base of the seventh transistor is connected to the collector of the seventh transistor, and the emitter of the seventh transistor is connected to the second end of the ninth capacitor and is grounded together.

Images