CN115955204A - A multi-stage amplifier, radio frequency circuit and electronic equipment - Google Patents

Abstract

The invention discloses a multistage amplifier, a radio frequency circuit and electronic equipment, and relates to the field of multistage amplifier design, wherein the multistage amplifier comprises an output selector, a first-stage amplifier, a second-stage amplifier, a third-stage amplifier and an (N + 1) th-stage amplifier. The front N-stage amplifiers comprise amplifiers, power detectors and inter-stage selectors, wherein the power detection switches can detect whether signals output by the pre-stage amplifiers meet preset target power; if yes, directly outputting the output signal to an output selector through the interstage selector and outputting the output signal by the output selector; if not, the output signal is continuously transmitted to the next-stage amplifier until the output signal meets the preset target power. Therefore, the purpose of amplifying the power of the output signal to different preset target powers can be achieved by using one multi-stage amplifier, the number of the multi-stage amplifiers required by the radio frequency circuit is reduced, and therefore the power consumption and the size of the radio frequency circuit are reduced.

Description

A multi-stage amplifier, radio frequency circuit and electronic equipment

technical field

The invention relates to the field of multistage amplifier design, in particular to a multistage amplifier, radio frequency circuit and electronic equipment.

Background technique

The structure of the radio frequency circuit is basically similar. It is generally composed of radio frequency transceivers, switches, low noise amplifiers and power amplifiers. It can be seen that amplifiers are widely used in radio frequency circuits, and radio frequency circuits often require a variety of amplifiers with different amplification stages to input The power of the signal is amplified to the target power. The number of stages of amplifier circuits commonly used in the prior art is fixed, so when the radio frequency circuit needs input signals of various target powers, it is necessary to set up a variety of amplifiers with different amplification stages, which will increase the overall power consumption and volume of the radio frequency circuit .

Contents of the invention

The purpose of the present invention is to provide a multi-stage amplifier, radio frequency circuit and electronic equipment, which can realize the purpose of amplifying the power of the output signal to different preset target powers by using a multi-stage amplifier, and reduce the multi-stage amplifier required by the radio frequency circuit. The number, thereby reducing the power consumption and size of the radio frequency circuit.

In order to solve the above technical problems, the present invention provides a multi-stage amplifier, including an output selector, a first-stage amplifier, a second-stage amplifier, a third-stage amplifier until the N+1th stage amplifier, wherein N is a positive integer;

The i-th stage amplifier includes an amplifier, a power detector and an interstage selector connected in sequence, the input end of the amplifier is used as the input end of the i-stage amplifier, and the first output end of the interstage selector is used as the i-stage amplifier the first output end of the interstage selector, the second output end of the interstage selector is used as the second output end of the i-th stage amplifier, and the first output end of the i-th stage amplifier is connected to the i-th input end of the output selector , the second output end of the i-th stage amplifier is connected to the input end of the i+1-th stage amplifier, the input end of the first-stage amplifier is the input end of the multi-stage amplifier, 1≤i≤N;

The N+1th stage amplifier includes the amplifier, the input end of the amplifier is used as the input end of the N+1st stage amplifier, the output end of the amplifier is used as the output end of the N+1st stage amplifier and the output selector The N+1th input terminal is connected, and the output terminal of the output selector is the output terminal of the multi-stage amplifier;

The power detector is used to detect whether the power of the output signal of the amplifier connected to the power detector is the preset target power; if so, control the first output terminal of the interstage selector connected to the power detector to conduct If not, then control the second output end of the interstage selector connected to the power detector to conduct;

The output selector is used to output the signal received by the input end of the output selector.

Preferably, it also includes an input matching network whose output terminal is connected to the input terminal of the first-stage amplifier, and the input terminal of the input matching network is used as the input terminal of the multi-stage amplifier;

The input matching network is used to filter the input signal of the multi-stage amplifier, and match the output impedance of the input signal with the input impedance of the first-stage amplifier.

Preferably, it also includes an interstage matching network arranged between the second output terminal of the i-th stage amplifier and the input end of the i+1-th stage amplifier;

The inter-stage matching network is used to filter the inter-stage signal output from the second output terminal of the i-th amplifier, and perform impedance matching between the output impedance of the i-th amplifier and the input impedance of the i+1-th amplifier.

Preferably, it also includes an output matching network whose input terminal is connected to the output terminal of the output selector, and the output terminal of the output matching network is used as the output terminal of the multi-stage amplifier;

The output matching network is used to filter the output signal output by the output selector, and perform impedance matching between the input impedance of the output signal and the load connected to the multi-stage amplifier.

Preferably, the input matching network, the output matching network and the inter-stage matching network are L-type matching networks, T-type matching networks or π-type matching networks, or any one or more combinations thereof;

The L-type matching network includes a first capacitor and a first inductance, the two ends of the first capacitor are used as input ends of the L-type matching network, and one end of the first capacitor is connected to one end of the first inductance , the other end of the first capacitor and the other end of the first inductor are used as the output end of the L-shaped matching network;

The T-type matching network includes a second capacitor, a third capacitor and a second inductor, the two ends of the second capacitor are used as the input terminals of the T-type matching network, and the two ends of the second inductor are respectively connected to the The first end of the second capacitor is connected to the first end of the third capacitor, the second end of the second capacitor is connected to the second end of the third capacitor, and the two ends of the third capacitor serve as the The output terminal of the T-shaped matching network;

The π-type matching network includes a fourth capacitor, a fifth capacitor, a third inductance, and a fourth inductance, the third inductance is connected in series with the fourth inductance and the common end connected to the first end of the fourth capacitor Connecting, the first end of the circuit connected in series and the second end of the fourth capacitor are used as the input end of the π-type matching network, and the other end of the circuit connected in series is connected to the first end of the fifth capacitor, The second end of the fifth capacitor is connected to the second end of the fourth capacitor, and the two ends of the fifth capacitor serve as the output ends of the π-type matching network.

Preferably, the N+1th stage amplifier also includes an output power detector and an output prompt module;

The input terminal of the output power detector is connected to the output terminal of the amplifier in the N+1th stage amplifier, and is used to transmit the output signal of the N+1th stage amplifier to the N+1th input of the output selector terminal, and generating a trigger signal when it is detected that the power of the output signal of the N+1th stage amplifier is not the preset target power;

The output prompt module is configured to generate prompt information for prompting that the amplification factor of the multi-stage amplifier does not meet requirements when the trigger signal is received.

Preferably, the output selector is a single-pole multi-throw switch, and the inter-stage selectors are all single-pole double-throw switches;

The N+1 fixed terminals of the single-pole multi-throw switch are respectively used as the N+1 input terminals of the output selector, and the movable terminals of the single-pole multi-throw switch are used as the output terminals of the output selector;

The moving end of the single pole double throw switch is used as the input end of the interstage selector, the first fixed end of the single pole double throw switch is used as the first output end of the interstage selector, and the single pole double throw switch is used as the first output end of the interstage selector. The second fixed end of the switch is used as the second output end of the interstage selector.

In order to solve the above-mentioned technical problems, the present application also provides a radio frequency circuit, including the above-mentioned multi-stage amplifier.

Preferably, it also includes a radio frequency chip, a signal processing circuit and a transmitting antenna;

The radio frequency chip is used to transmit the input signal to the multi-stage amplifier, so that the multi-stage amplifier amplifies the power of the input signal to a preset target power;

The signal processing circuit is used to filter and integrate the output signal of the multi-stage amplifier, and output the filtered and integrated output signal to the transmitting antenna;

The transmitting antenna is used to transmit the filtered and integrated output signal.

In order to solve the above-mentioned technical problem, the present application also provides an electronic device, including the above-mentioned radio frequency circuit.

To sum up, the present invention provides a multi-stage amplifier, radio frequency circuit and electronic equipment, including an output selector, a first-stage amplifier, a second-stage amplifier, a third-stage amplifier and up to the N+1th stage amplifier. The first N stages of amplifiers all include amplifiers, power detectors and interstage selectors. Among them, the power detection switch can detect whether the output signal of the stage amplifier meets the preset target power; if so, the output signal is directly output through the interstage selector to the output selector and the output signal is output by the output selector; if not, continue to transmit the output signal to the next stage amplifier until the output signal meets the preset target power. Therefore, the present application can use a multi-stage amplifier to amplify the power of the output signal to different preset target powers, reducing the number of multi-stage amplifiers required by the radio frequency circuit, thereby reducing the power consumption and volume of the radio frequency circuit .

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the prior art and the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the structural representation of a kind of multistage amplifier provided by the present application;

FIG. 2 is a schematic diagram of a working flow of a multi-stage amplifier provided in the present application.

Detailed ways

The core of the present invention is to provide a multi-stage amplifier, radio frequency circuit and electronic equipment, which can use a multi-stage amplifier to amplify the power of the output signal to different preset target powers, reducing the number of multi-stage amplifiers required by the radio frequency circuit. The number, thereby reducing the power consumption and size of the radio frequency circuit.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to FIG. 1. FIG. 1 is a schematic structural diagram of a multi-stage amplifier provided by the present application. The multi-stage amplifier includes an output selector 1, a first-stage amplifier, a second-stage amplifier, a third-stage amplifier until the N+1th stage stage amplifier, wherein, N is a positive integer;

The i-th stage amplifier includes an amplifier 2, a power detector 3 and an interstage selector 4 connected in sequence, the input end of the amplifier 2 is used as the input end of the i-th stage amplifier, and the first output end of the interstage selector 4 is used as the i-th stage The first output end of the amplifier, the second output end of the interstage selector 4 is used as the second output end of the i-th stage amplifier, and the first output end of the i-th stage amplifier is connected with the i-th input end of the output selector 1, The second output end of the i-th stage amplifier is connected to the input end of the i+1-th stage amplifier, the input end of the first-stage amplifier is the input end of the multi-stage amplifier, 1≤i≤N;

The N+1th stage amplifier includes an amplifier 2, the input end of the amplifier 2 is used as the input end of the N+1st stage amplifier, the output end of the amplifier 2 is used as the output end of the N+1st stage amplifier and the N+th stage of the output selector 1 One input terminal is connected, and the output terminal of the output selector 1 is the output terminal of the multistage amplifier;

Power detector 3 is used to detect whether the power of the output signal of the amplifier 2 that is connected with power detector 3 is preset target power; If not, then control the second output terminal of the interstage selector 4 connected with the power detector 3 to conduct;

The output selector 1 is used to output the signal received by the input terminal of the output selector 1 .

The multi-stage amplifier provided by the present application can automatically output the signal whose power reaches the preset target power. Specifically, the multi-stage amplifier specifically includes the N+1th stage amplifier, wherein the first N-stage amplifiers include amplifier 2, power detection The power detector 3 and the interstage selector 4, the power detector 3 can detect the power of the amplifier 2 connected to itself, and after detecting that the power of the signal output by the amplifier 2 connected to itself reaches the preset target power, it is connected to itself through control The first output terminal of the inter-stage selector 4 is turned on, that is, the signal output by the amplifier 2 of its own stage is directly transmitted to the output selector 1 so that the output selector 1 outputs the signal; when it detects that the amplifier 2 connected to itself When the power of the output signal does not reach the preset target power, the second output terminal of the interstage selector 4 connected to itself is controlled to be turned on, which means that the signal output by the amplifier 2 of its own stage is transmitted to the next stage amplifier 2 so as to continue The power of the signal is amplified until the preset target power is met.

Please refer to Figure 2, Figure 2 is a schematic diagram of the workflow of a multi-stage amplifier provided by yourself, in Figure 2, Poutn is the power of the signal output by the Nth stage amplifier, Pneed is the preset target power, and SPNT is the output selector 1. The input signal is transmitted to the amplifier 2 in the first-stage amplifier through the input matching network, and then the power detector 3 in the first-stage amplifier detects whether the power of the signal output by the amplifier 2 is the preset target power, if so, it is directly output through the SPNT, if Otherwise, transmit to the interstage matching network connected with the first stage amplifier and repeat the above operation.

To sum up, the present invention provides a multi-stage amplifier, including an output selector 1, a first-stage amplifier, a second-stage amplifier, a third-stage amplifier and up to the N+1th stage amplifier. The front N-stage amplifiers all include amplifier 2, power detector 3 and interstage selector 4, wherein the power detection switch can detect whether the signal output by this stage amplifier 2 meets the preset target power; The output signal is directly output to the output selector 1 and the output signal is output by the output selector 1; if not, the output signal is continuously transmitted to the next stage amplifier 2 until the output signal meets the preset target power. Therefore, the present application can use a multi-stage amplifier to amplify the power of the output signal to different preset target powers, reducing the number of multi-stage amplifiers required by the radio frequency circuit, thereby reducing the power consumption and volume of the radio frequency circuit .

On the basis of above-mentioned embodiment:

As a preferred embodiment, it also includes an input matching network whose output end is connected to the input end of the first-stage amplifier, and the input end of the input matching network is used as the input end of the multi-stage amplifier;

The input matching network is used to filter the input signal of the multi-stage amplifier, and match the output impedance of the input signal with the input impedance of the first-stage amplifier.

In this embodiment, an input matching network is provided at the input end of the first-stage amplifier, and the input end of the input matching network is used as an input end of the multi-stage amplifier, and the input signal is input to the first-stage amplifier through the input matching network. The input matching network filters the input signal to the multi-stage amplifier to ensure the power of the required frequency signal, suppresses the harmonic components other than the required frequency, and matches the input signal with the input impedance of the first-stage amplifier to make the amplifier 2 to obtain the maximum excitation power. It should be noted that this application does not specifically limit the specific circuit structure of the input matching network, which can be selected according to actual conditions.

As a preferred embodiment, it also includes an inter-stage matching network arranged between the second output end of the i-th stage amplifier and the input end of the (i+1)-th stage amplifier;

The inter-stage matching network is used to filter the inter-stage signal output from the second output terminal of the i-th amplifier, and perform impedance matching between the output impedance of the i-th amplifier and the input impedance of the (i+1)-th amplifier.

In this embodiment, an interstage matching network is arranged between the amplifiers 2 of each stage in the first N stages of amplifiers, and the interstage matching network filters the interstage signal output by the output terminal of the amplifier 2 to ensure that the load obtains the power of the operating frequency and suppresses the Harmonic components and interference other than the operating frequency, and impedance matching is performed to transmit the signal power to the load, further enabling the amplifier 2 to obtain the maximum excitation power. It should be noted that this application does not specifically limit the specific circuit structure of the inter-stage matching network, which can be selected according to actual conditions.

As a preferred embodiment, it also includes an output matching network whose input end is connected to the output end of the output selector 1, and the output end of the output matching network is used as the output end of the multistage amplifier;

The output matching network is used to filter the output signal output by the output selector 1, and perform impedance matching between the input impedance of the output signal and the load connected to the multi-stage amplifier.

In this embodiment, an output matching network is provided at the output end of the output selector 1. The function of the output matching network is to perform impedance matching between the input impedance of the output signal and the load connected to the multi-stage amplifier, and transform the external load resistance into an amplifier 2 to ensure the maximum output power, and at the same time filter the output signal of the output selector 1 to further optimize the working performance of the multi-stage amplifier, thereby ensuring the performance of the radio frequency circuit. It should be noted that this application does not specifically limit the specific circuit structure of the output matching network, which can be selected according to actual conditions.

As a preferred embodiment, the input matching network, the output matching network and the interstage matching network are L-type matching networks, T-type matching networks or π-type matching networks, or any combination of one or more of them;

The L-shaped matching network includes a first capacitor and a first inductor, and the two ends of the first capacitor are used as input ends of the L-shaped matching network, and one end of the first capacitor is connected to one end of the first inductor, and the other end of the first capacitor and the first The other end of the inductor is used as the output end of the L-shaped matching network;

The T-shaped matching network includes a second capacitor, a third capacitor, and a second inductor. The two ends of the second capacitor are used as the input terminals of the T-shaped matching network. The first end of the capacitor is connected, the second end of the second capacitor is connected to the second end of the third capacitor, and the two ends of the third capacitor are used as the output ends of the T-type matching network;

The π-type matching network includes a fourth capacitor, a fifth capacitor, a third inductance, and a fourth inductance. The third inductance is connected in series with the fourth inductance and the common end connected to the first end of the fourth capacitor is connected. The first end of the circuit after series connection One end and the second end of the fourth capacitor are used as the input end of the π-type matching network, and the other end of the circuit connected in series is connected to the first end of the fifth capacitor, and the second end of the fifth capacitor is connected to the second end of the fourth capacitor. The two ends of the fifth capacitor are used as the output ends of the π-type matching network.

The input matching network, the interstage matching network and the output matching network are composed of capacitors and inductors connected in series and parallel. Usually, the standard impedance of the radio frequency circuit is 50 ohms. The functions of the input matching network, the interstage matching network and the output matching network are roughly similar. One is to filter to ensure the power of the required frequency signal, and to suppress harmonic components and interference other than the required frequency. All high frequency signals can be passed to the point of load. When the impedance of the input end is matched, the transmission line obtains the maximum power; when the impedance of the output end is matched, there are only voltage waves and current waves traveling to the terminal on the transmission line, and all the energy carried is absorbed by the load. The input matching network, the interstage matching network and the output matching network can all choose any one of L-type matching network, T-type matching network or π-type matching network, so as to realize the above functions and further optimize the performance of the multi-stage amplifier.

As a preferred embodiment, the N+1th stage amplifier also includes an output power detector and an output prompt module;

The input end of the output power detector is connected to the output end of the amplifier 2 in the N+1th stage amplifier, and is used to transmit the output signal of the N+1st stage amplifier to the N+1th input end of the output selector, and Generating a trigger signal when it is detected that the power of the output signal of the N+1th stage amplifier is not the preset target power;

The output prompting module is used to generate prompt information for prompting that the amplification factor of the multi-stage amplifier does not meet the requirement when the trigger signal is received.

Considering that in practical applications, the power of the input signal may still not reach the preset target power after the input signal is amplified by the first-stage amplifier to the N+1-th stage amplifier of the multi-stage amplifier. The structure of the amplifier is adjusted or the input signal is adjusted. Therefore, in this embodiment, an output power detector and an output prompting module are provided in the N+1 stage amplifier, that is, the last stage amplifier in the multi-stage amplifier. The output power detector is used to output the output signal of the amplifier 2 in the N+1 amplifier to prevent the staff from thinking that the multi-stage amplifier itself is faulty, and at the same time detect the output signal of the N+1-th amplifier, that is, the final output signal of the multi-stage amplifier. Whether the power of the output signal is the preset target power, when the power of the final output signal of the multi-stage amplifier is not the preset target power, trigger the output prompt module to generate prompt information so that the staff can timely understand the structure of the multi-stage amplifier or the input signal Adjust the frequency and so on to further optimize the performance of the multi-stage amplifier.

As a preferred embodiment, the output selector 1 is a single-pole multi-throw switch, and the inter-stage selectors 4 are all single-pole double-throw switches;

The N+1 fixed terminals of the single-pole multi-throw switch are respectively used as the N+1 input terminals of the output selector 1, and the movable terminals of the single-pole multi-throw switch are used as the output terminals of the output selector 1;

The moving end of the single pole double throw switch is used as the input end of the interstage selector 4, the first fixed end of the single pole double throw switch is used as the first output end of the interstage selector 4, and the second fixed end of the single pole double throw switch is used as the The second output terminal of the interstage selector 4.

In this embodiment, the interstage selector 4 is a single-pole double-throw switch, and the output selector 1 is a single-pole multiple-throw switch. When the power detector 3 in the i-stage amplifier detects that the power of the signal output by the amplifier 2 connected to itself is a preset target power, it controls the fixed end of the single-pole double-throw switch to be connected to the first fixed end so that the The signal is directly transmitted to the i-th fixed end of the SPMT switch, and then output through the moving end of the SPMT switch; the power detector 3 in the front N-stage amplifier detects the signal output from the amplifier 2 connected to itself When the power does not reach the preset target power, the moving end of the SPDT switch is controlled to be connected to the second non-moving end so as to transmit the signal to the (i+1)th stage amplifier for further amplification of the signal. Moreover, a single-pole, multi-throw switch is selected as the output selector 1, and a single-pole, double-throw switch is selected as the inter-stage selector 4, which is low in cost and easy to implement.

The present application also provides a radio frequency circuit, including the above-mentioned multi-stage amplifier.

For the relevant introduction of a radio frequency circuit provided in the present application, please refer to the above embodiment of the multi-stage amplifier, and the present application will not repeat it here.

As a preferred embodiment, it also includes a radio frequency chip, a signal processing circuit and a transmitting antenna;

The radio frequency chip is used to transmit the input signal to the multi-stage amplifier, so that the multi-stage amplifier can amplify the power of the input signal to the preset target power;

The signal processing circuit is used to filter and integrate the output signals of the multi-stage amplifier, and output the filtered and integrated output signals to the transmitting antenna;

The transmitting antenna is used to transmit the filtered and integrated output signal.

In this embodiment, the radio frequency chip also includes a radio frequency chip, a signal processing circuit and a transmitting antenna. The radio frequency chip transmits the input signal to a multi-stage amplifier, and the multi-stage amplifier amplifies the power of the input signal to a preset target power. The signal processing circuit may include The filter circuit and the frequency mixing circuit filter and integrate the output signals of the multi-stage amplifier, and transmit the filtered and integrated signal output value to the antenna, and the transmitting antenna transmits the output signal to realize the function of the radio frequency circuit, and please provide the radio frequency The circuit can automatically realize the function of amplifying the power of the input signal to the preset target power.

The present application also provides an electronic device, including the above-mentioned radio frequency circuit.

It should be noted that the electronic devices provided in this application can be watches, bracelets, earphones, head-mounted wearable devices, or smart home devices such as speakers and cameras, and can also be mobile phones, game controllers, or locators. This is not particularly limited.

It should be noted that in this specification, relative terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations Any such actual relationship or order exists between. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A multistage amplifier, characterized in that, comprises an output selector, a first stage amplifier, a second stage amplifier, a third stage amplifier until the N+1 stage amplifier, wherein N is a positive integer; The i-th stage amplifier includes an amplifier, a power detector and an interstage selector connected in sequence, the input end of the amplifier is used as the input end of the i-stage amplifier, and the first output end of the interstage selector is used as the i-stage amplifier the first output end of the interstage selector, the second output end of the interstage selector is used as the second output end of the i-th stage amplifier, and the first output end of the i-th stage amplifier is connected to the i-th input end of the output selector , the second output end of the i-th stage amplifier is connected to the input end of the i+1-th stage amplifier, and the input end of the first-stage amplifier is used as the input end of the multi-stage amplifier, 1≤i≤N; The N+1th stage amplifier includes the amplifier, the input end of the amplifier is used as the input end of the N+1st stage amplifier, the output end of the amplifier is used as the output end of the N+1st stage amplifier and the output selector The N+1th input terminal is connected, and the output terminal of the output selector is the output terminal of the multi-stage amplifier; The power detector is used to detect whether the power of the output signal of the amplifier connected to the power detector is the preset target power; if so, control the first output terminal of the interstage selector connected to the power detector to conduct If not, then control the second output end of the interstage selector connected to the power detector to conduct; The output selector is used to output the signal received by the input end of the output selector. 2. multistage amplifier as claimed in claim 1, is characterized in that, also comprises the input matching network that output end is connected with the input end of described first stage amplifier, the input end of described input matching network is as described multistage the input of the amplifier; The input matching network is used to filter the input signal of the multi-stage amplifier, and match the output impedance of the input signal with the input impedance of the first-stage amplifier. 3. The multistage amplifier according to claim 2, further comprising an interstage matching network arranged between the second output of the i-th stage amplifier and the input of the (i+1)-th stage amplifier; The inter-stage matching network is used to filter the inter-stage signal output from the second output terminal of the i-th amplifier, and perform impedance matching between the output impedance of the i-th amplifier and the input impedance of the i+1-th amplifier. 4. multistage amplifier as claimed in claim 3, is characterized in that, also comprises the output matching network that input terminal is connected with the output end of described output selector, the output end of described output matching network is as described multistage amplifier the output terminal; The output matching network is used to filter the output signal output by the output selector, and perform impedance matching between the input impedance of the output signal and the load connected to the multi-stage amplifier. 5. The amplifier circuit according to claim 4, wherein the input matching network, the output matching network and the interstage matching network are L-type matching networks or T-type matching networks or π-type matching networks. Any one or combination of multiples; The L-type matching network includes a first capacitor and a first inductance, the two ends of the first capacitor are used as input ends of the L-type matching network, and one end of the first capacitor is connected to one end of the first inductance , the other end of the first capacitor and the other end of the first inductor are used as the output end of the L-shaped matching network; The T-type matching network includes a second capacitor, a third capacitor and a second inductor, the two ends of the second capacitor are used as the input terminals of the T-type matching network, and the two ends of the second inductor are respectively connected to the The first end of the second capacitor is connected to the first end of the third capacitor, the second end of the second capacitor is connected to the second end of the third capacitor, and the two ends of the third capacitor serve as the The output terminal of the T-shaped matching network; The π-type matching network includes a fourth capacitor, a fifth capacitor, a third inductance, and a fourth inductance, the third inductance is connected in series with the fourth inductance and the common end connected to the first end of the fourth capacitor connected, the first end of the series connected circuit and the second end of the fourth capacitor are used as the input end of the π-type matching network, and the other end of the connected circuit is connected to the first end of the fifth capacitor, The second end of the fifth capacitor is connected to the second end of the fourth capacitor, and the two ends of the fifth capacitor serve as the output ends of the π-type matching network. 6. The multistage amplifier according to claim 1, wherein the N+1 stage amplifier also includes an output power detector and an output prompt module; The input terminal of the output power detector is connected to the output terminal of the amplifier in the N+1th stage amplifier, and is used to transmit the output signal of the N+1th stage amplifier to the N+1th input of the output selector terminal, and generating a trigger signal when it is detected that the power of the output signal of the N+1th stage amplifier is not the preset target power; The output prompt module is configured to generate prompt information for prompting that the amplification factor of the multi-stage amplifier does not meet requirements when the trigger signal is received. 7. The multistage amplifier according to any one of claims 1 to 6, wherein the output selector is a single-pole multi-throw switch, and the interstage selectors are all single-pole double-throw switches; The N+1 fixed terminals of the single-pole multi-throw switch are respectively used as the N+1 input terminals of the output selector, and the movable terminals of the single-pole multi-throw switch are used as the output terminals of the output selector; The moving end of the single pole double throw switch is used as the input end of the interstage selector, the first fixed end of the single pole double throw switch is used as the first output end of the interstage selector, and the single pole double throw switch is used as the first output end of the interstage selector. The second fixed end of the switch is used as the second output end of the interstage selector. 8. A radio frequency circuit, characterized by comprising the multi-stage amplifier according to any one of claims 1 to 7. 9. The radio frequency circuit according to claim 8, further comprising a radio frequency chip, a signal processing circuit and a transmitting antenna; The radio frequency chip is used to transmit the input signal to the multi-stage amplifier, so that the multi-stage amplifier amplifies the power of the input signal to a preset target power; The signal processing circuit is used to filter and integrate the output signal of the multi-stage amplifier, and output the filtered and integrated output signal to the transmitting antenna; The transmitting antenna is used to transmit the filtered and integrated output signal. 10. An electronic device, comprising the radio frequency circuit according to any one of claims 7 to 9.

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