A system and method for adjusting multi-level power supply voltage of a power amplifier based on transmitter branch gain setting

Abstract

The present invention discloses a system and method for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting. The system comprises a radio frequency transceiver, a step-up / step-down DC-DC converter, a radio frequency predistorter and a power amplifier. The radio frequency transceiver sends an analog voltage signal to the step-up / step-down DC-DC converter to control the step-up / step-down DC-DC converter to output a corresponding power supply voltage value to the power amplifier. The radio frequency transceiver sends a radio frequency excitation signal to the radio frequency predistorter, and the radio frequency predistorter sends the processed radio frequency predistortion signal to an input end of the power amplifier. The power amplifier amplifies the received radio frequency predistortion signal, and a part of the generated radio frequency amplification signal is sent to an antenna for transmission through a duplexer, and another small part is fed back to the radio frequency predistorter through a coupler, and is also fed back to a receiver input end of the radio frequency transceiver.

Description

Technical Field

[0001] The invention belongs to the field of radio communications, and in particular relates to a system and method for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting. Background Art

[0002] Usually, the power amplifier is used as a terminal device unit of a wireless transmitter system or device. When the power amplifier amplifies the RF signal, the power supply voltage of the amplifier remains fixed regardless of whether the average power of the output RF signal after amplification is strong or weak. When the power of the RF signal amplified by the power amplifier is weak, the power supply voltage of the amplifier remains fixed, so the DC power consumption of the power amplifier is also large, and the power efficiency is reduced. One of the effective ways to improve power efficiency is to dynamically adjust the power supply voltage value of the amplifier according to the power strength of the power amplifier output signal. The power supply voltage increases as the power of the amplifier output signal increases, and vice versa. This adjustment of the power supply voltage value can effectively improve power efficiency, especially when the output signal power is weak or relatively weak.

[0003] The power modulator or the step-up / step-down DC-DC converter can provide a variable power supply voltage to the power amplifier. The variable power supply voltage is based on the envelope change of the RF signal input to the power amplifier or the average power of the RF signal output by the power amplifier in the next time period. Therefore, the corresponding methods of providing a variable power supply voltage to the power amplifier are respectively called envelope tracking (ET) technology and average power tracking (APT) technology (such as Figure 1 shown).

[0004] Envelope tracking technology is to extract the RF signal envelope before the RF signal enters the power amplifier, and then use the envelope signal as input to control the power modulator (such as Figure 1 The envelope tracking component in the power modulator is used to make the output signal of the power modulator track the envelope change of the RF signal and use it as the power supply voltage of the power amplifier. The power supply voltage is a dynamic power supply voltage, and the dynamic power supply voltage tracks the envelope change of the RF signal, so the power supply current also rises or falls with the envelope change of the RF signal, which reduces the excess DC voltage and ensures that the amplifier can output instantaneous power, thereby maximizing the power efficiency and extending the duration of the power battery. However, the disadvantage of this technology is that due to the transmission bandwidth limitation of the power modulator, the envelope change of the RF signal output by the power modulator will cause serious nonlinear distortion in the power amplifier, thereby reducing the performance of the transmitted signal.

[0005] Compared with envelope tracking (ET) technology, average power tracking (APT) technology uses the average power measurement or estimation of the RF signal over a period of time to generate a voltage through a step-up / step-down DC-DC converter (such as Figure 1The power supply voltage is set by the average power tracking component in the middle. Compared with the envelope tracking (ET) technology, although the power amplifier transmission power efficiency is slightly lower, the amplified RF signal has good performance in suppressing in-band spectrum sidelobes and out-of-band spurious signals, and the hardware implementation is relatively simple and low-cost. Compared with the conventional fixed power supply voltage power amplifier, the average power tracking (APT) has the advantages of high power amplifier transmission power efficiency and less complex hardware implementation. Especially for the transmission signal with a large peak power to average power ratio (PAPR) and low amplifier input RF signal power, compared with the conventional fixed power supply voltage power amplifier, the average power tracking (APT) can further improve the transmission power efficiency of the power amplifier. However, the disadvantage of this technology is that it is necessary to measure or estimate the average power of the RF signal in the next period of time, but the difficulty is how to measure or estimate the signal power in real time during the period, and adjust the power supply voltage of the power amplifier based on the measured or estimated signal power without delaying and affecting the transmission of the RF signal. Summary of the invention

[0006] In view of the above-mentioned technical problems, the present invention proposes a method for directly adjusting the multi-level power supply voltage of a power amplifier according to the transmitter branch gain setting for the next frame transmission radio frequency signal in a wireless transceiver and communication equipment, providing the power amplifier with a corresponding power supply voltage value to reduce excess DC power consumption, thereby improving the power efficiency of the power amplifier, and simultaneously using a radio frequency predistorter (RFPD) to assist in compensating for the nonlinear distortion caused by the power amplifier under different power supply voltage excitations.

[0007] The transmitter branch gain is used to control the size or strength of the average power of the RF signal output by the power amplifier in the next frame, and the relationship between it and the average power of the output RF signal is determined through test calibration in offline mode.

[0008] The technical solution adopted by the present invention is:

[0009] A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting, the system comprising

[0010] A radio frequency transceiver, the radio frequency transceiver comprising a radio frequency transmitter and a radio frequency receiver, wherein the radio frequency transmitter is used to output an analog voltage signal to control the output variable multi-level power supply voltage value of the step-up / step-down DC-DC converter as the power supply voltage of the power amplifier, and output a radio frequency excitation signal to the radio frequency predistorter for predistortion processing;

[0011] A step-up / step-down DC-DC converter is used to receive an analog voltage signal output by a radio frequency transmitter, and convert an input DC voltage of the step-up / step-down DC-DC converter into a corresponding value of a multi-level power supply voltage as an output voltage to provide a power supply voltage value to a power amplifier, wherein the output voltage may be less than or greater than the input voltage;

[0012] The RF predistorter is used to receive the RF excitation signal output by the RF transmitter, perform predistortion processing on the RF excitation signal to obtain the RF predistortion signal, and output the RF predistortion signal to the power amplifier; it is also used to receive the RF amplified signal output by the power amplifier, which is a branch feedback RF signal coupled by the first coupler, and receive the RF excitation signal output by the RF transmitter, which is a branch RF signal coupled by the second coupler;

[0013] The power amplifier is used to receive a multi-level power supply voltage and a radio frequency predistortion signal, and amplify the radio frequency predistortion signal under a corresponding power supply voltage supply, and send the amplified radio frequency predistortion signal as a radio frequency amplified signal to the antenna, and a small part of a branch signal of the radio frequency amplified signal is coupled by a first coupler and then fed back to the radio frequency predistorter; it is also used to feed back the radio frequency signal power strength indication analog voltage signal to the radio frequency transceiver.

[0014] Preferably, the radio frequency predistorter comprises

[0015] An error signal generator is used to receive a branch feedforward RF signal coupled by a second coupler from an RF excitation signal output by an RF transmitter and a branch feedback RF signal coupled by a first coupler from an RF amplified signal output by a power amplifier, and obtain an equivalent baseband signal of the feedforward RF signal and an equivalent baseband signal of the feedback RF signal through down-conversion and demodulation respectively, and generate an error signal according to the difference between the equivalent baseband signal of the input RF signal and the equivalent baseband signal of the feedback RF signal in the time domain or the frequency domain, and send the error signal to a predistortion coefficient generator;

[0016] A predistortion coefficient generator adaptively updates the predistortion coefficient according to the error signal until the error signal decreases and converges, and sends it to the predistortion polynomial generator;

[0017] The predistortion polynomial generator processes the baseband signal of the input feedforward RF signal after down-conversion, demodulation, and low-pass filtering according to the updated predistortion coefficient to obtain a nonlinear polynomial, which is sent to the predistortion generator;

[0018] The predistortion generator processes the RF excitation signal according to the nonlinear polynomial to obtain a RF predistortion signal, which is sent to the power amplifier for power amplification.

[0019] Preferably, the radio frequency transmitter comprises

[0020] An analog-to-digital converter, used for receiving and converting an analog signal indicating the power strength of the radio frequency signal amplified by the power amplifier, and sending the converted digital signal to the gain index control unit;

[0021] The gain index control unit is used to calibrate the measured transmission power and the target power in an offline mode before the system leaves the factory, so that the error between the two is less than the threshold value, and set the corresponding gain index as the output to control the transmission branch gain search unit and the control index simplification unit respectively;

[0022] The transmitting branch gain search unit is used to receive the gain index output by the gain index control unit, allocate the power amplification factor or gain of each circuit in the transmitting branch circuit unit by looking up a table, and output a signal to set the corresponding power gain value of each circuit controlled by the transmitting branch circuit unit;

[0023] The transmitting branch circuit unit is used to set the corresponding power gain value of each circuit according to the power amplification factor or gain of each circuit of the transmitting branch assigned by the transmitting branch gain search unit, so as to determine the power of the RF excitation signal at the input end of the RF predistorter;

[0024] A control index simplification unit is used to receive the gain index output by the gain index control unit, simplify it to obtain a simplified control index, and send it to the power supply voltage search unit;

[0025] The power supply voltage search unit is used to find the corresponding power supply voltage value according to the received simplified gain index, and convert it into an analog voltage signal through the first digital-to-analog converter to control the step-up / step-down DC-DC converter to output the corresponding voltage level as the power amplifier power supply voltage value.

[0026] Preferably, the transmitting branch circuit unit includes a second digital-to-analog converter, an analog filter, an amplifier, a modulator, an up-converter and a radio frequency power amplifier driver;

[0027] Among them, the second digital-to-analog converter converts the digital baseband signal into an analog baseband signal, and the analog filter is located at the output end of the second digital-to-analog converter and is used to remove high-frequency components; the amplifier appropriately amplifies the filtered baseband signal, and its amplification gain is used as a part of the transmission branch gain; the modulator uses the amplified input baseband signal to modulate the carrier signal, and the modulated signal realizes spectrum shifting, that is, the low-frequency spectrum is moved to the high-frequency spectrum, and the up-converter and the modulator are designed together to realize spectrum shifting; the RF power amplifier driver performs power amplification on the modulated signal to meet the input signal power requirement of the subsequent power amplifier, and the power amplifier amplification gain is fixed, while the RF power amplifier driver amplification gain is adjustable, and the output signal power of the power amplifier can be increased or decreased by adjustment;

[0028] The sum of the power gain decibels of the analog filter, amplifier, modulator, up-converter and RF power amplifier driver constitutes the transmission branch gain decibel, and the sum of the transmission branch gain decibel and the power amplifier gain jointly determines the output power of the power amplifier.

[0029] Preferably, the process of simplifying the gain index by the control index simplification unit includes: simplifying the gain index range into several limited areas in order of size, and setting a representative code for each area, the representative code of each area corresponds to the corresponding power amplifier output power value range, and providing the corresponding power supply voltage value to the power amplifier through the power supply voltage search unit, and the power supply voltage value indirectly sets the size of the average power area of ​​the next frame transmission signal according to the representative code of the gain index area, so as to select a reasonable power supply voltage value to avoid using redundant and excessive power supply voltage values.

[0030] Preferably, the power supply voltage search unit directly sets or adjusts the power supply voltage of the power amplifier according to the area where the transmitter branch gain index is located and through a step-up / step-down DC-DC converter, and uses it as the power supply voltage of the power amplifier when transmitting the next frame of RF signal. The power supply voltage value is set before the next frame of transmission signal and is stable when the next frame of transmission signal is transmitted.

[0031] Preferably, in the offline mode, the input signal and the output signal of the power amplifier are respectively collected to obtain the corresponding RF predistortion coefficient as the initial predistortion coefficient in the online mode. Therefore, the system also includes a RF signal generator, a boost / buck DC-DC controller, an attenuator, a spectrum analyzer and a computer. The output end of the RF signal generator is connected to the power amplifier, the attenuator, the spectrum analyzer and the computer in sequence to collect the output signal of the power amplifier. The output end of the RF signal generator is also directly connected to the spectrum analyzer to collect the input signal of the power amplifier. The boost / buck DC-DC controller outputs an analog voltage signal to control the output voltage of the boost / buck DC-DC converter, and the voltage is the power supply voltage of the power amplifier.

[0032] Preferably, in offline mode, the RF signal generator outputs a modulated RF signal for a specific application. First, the modulated RF signal is output to a power amplifier for amplification. The amplified RF signal is attenuated by an attenuator and then sent to a spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal output of the power amplifier, and the signal is sent to a computer. After that, the modulated RF signal is directly output to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal input of the power amplifier, and the signal is sent to the computer. The computer digitizes the equivalent baseband signal of the RF signal output of the power amplifier and the equivalent baseband signal of the RF signal input of the power amplifier.

[0033] Preferably, in an offline state, the computer obtains a predistortion coefficient by respectively collecting an equivalent baseband signal output by the power amplifier RF signal and an equivalent baseband signal input by the power amplifier RF signal, and substituting the collected data into a least squares (LS) formula. The predistortion coefficient is an initial coefficient group corresponding to the power supply voltage value. Different power supply voltage values ​​correspond to different predistortion coefficient groups, and different initial predistortion coefficient groups are generated. The predistortion coefficient groups corresponding to different power supply voltage values ​​are sent to a polynomial coefficient table corresponding to different voltage values ​​in the RF transmitter for storage. The predistortion coefficient group is used as an initial predistortion coefficient in the online mode of the RF predistorter, and the predistortion coefficient is adaptively updated on this basis to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages in the online mode.

[0034] Preferably, the process of the RF predistorter adaptively updating the predistortion coefficient in the online mode to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages includes:

[0035] Step S1: the error signal generator collects the feedforward RF signal coupled by the second coupler of the RF excitation signal output by the RF transceiver and the feedback RF signal coupled by the first coupler of the RF amplified signal output by the power amplifier, and obtains the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal after down-conversion and demodulation respectively, and generates the error signal by using the difference between the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal in the time domain, or obtains the error signal according to the strength of the leakage signal outside the frequency band of the feedback RF signal in the frequency domain, and then substitutes the error signal into the adaptive display algorithm to update the initial pre-distortion coefficient;

[0036] Step S2: sending the predistortion coefficient updated in step S1 to a predistortion polynomial generator to generate a predistortion polynomial, sending the predistortion polynomial to the predistortion generator, the predistortion polynomial is a complex polynomial, which includes an in-phase component and an orthogonal component polynomial, and both have nonlinear characteristics;

[0037] Step S3: In the predistortion generator, the in-phase component of the predistortion polynomial is multiplied by the in-phase signal of the input RF excitation signal, and the orthogonal component of the predistortion polynomial is multiplied by the orthogonal signal of the input RF excitation signal; then the results of the two calculations are added to generate the required RF predistortion signal.

[0038] A method for adjusting a multi-level power supply voltage of a power amplifier based on a transmitter branch gain setting, the method comprising:

[0039] In the online mode, the control index simplification unit in the radio frequency transmitter simplifies the received gain index to obtain a simplified control index, and the power supply voltage search unit searches for the corresponding power supply voltage value according to the input simplified control index, and converts it into an analog voltage signal through the first digital-to-analog converter to control the output voltage level of the boost / buck DC-DC converter as the corresponding actual power supply voltage of the power amplifier in the next frame transmission power value range;

[0040] The power amplifier works under different power supply voltages, and the corresponding initial pre-distortion coefficient of the RF pre-distorter is configured through the RF transceiver. The RF pre-distorter enters the initial pre-distortion coefficient adaptive adjustment stage to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages.

[0041] The transmitting branch gain search unit in the RF transmitter allocates the received gain index to the power gain or gain of each circuit in the transmitting branch circuit unit by looking up the table. The transmitting branch circuit unit sets the corresponding power gain value of each circuit according to the allocated power gain or gain of each circuit of the transmitting branch, and determines the power of the RF excitation signal at the input end of the RF predistorter;

[0042] The RF excitation signal output by the RF transmitter is sent to the RF predistorter through a branch of feedforward RF output coupled signals coupled by the second coupler, and the baseband signal of the feedforward RF signal is obtained after down-conversion and demodulation processing, and is sent to the error signal generator. At the same time, the error signal generator also collects the RF amplification signal output by the power amplifier, and a branch of feedback RF signal is coupled by the first coupler, and the baseband signal of the feedback RF signal is obtained after down-conversion and demodulation processing. The error signal is generated by using the difference between the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal in the time domain, or the error signal is obtained according to the strength of the leakage signal outside the frequency band of the feedback RF signal in the frequency domain. , then substitute the error signal into the adaptive algorithm to update the initial predistortion coefficient, and send the updated predistortion coefficient to the predistortion polynomial generator to generate a predistortion polynomial, which is a complex polynomial, including an in-phase component and an orthogonal component polynomial. The predistortion polynomial is sent to the predistortion generator, and in the predistortion generator, the in-phase component of the predistortion polynomial is multiplied by the in-phase signal of the input RF excitation signal, and the orthogonal component of the predistortion polynomial is multiplied by the orthogonal signal of the input RF excitation signal; then add the results of the two calculations to generate the required RF predistortion signal, and send the RF predistortion signal to the power amplifier for amplification processing;

[0043] or

[0044] In the offline mode, the RF signal generator outputs a modulated RF signal for a specific application. First, the modulated RF signal is output to the power amplifier for amplification. The amplified RF signal is attenuated by the attenuator and then sent to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal output of the power amplifier, and sent to the computer. After that, the modulated RF signal is directly output to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal input of the power amplifier, and sent to the computer. The computer compares the collected equivalent baseband signal output by the power amplifier RF signal with the power amplifier RF signal. The equivalent baseband signal of the amplifier RF signal input is substituted into the least squares formula to obtain the pre-distortion coefficient, which is the initial coefficient group under the corresponding power supply voltage value. Different power supply voltage values ​​correspond to different pre-distortion coefficient groups, and different initial pre-distortion coefficient groups are generated. The pre-distortion coefficient groups corresponding to different power supply voltage values ​​are sent to the polynomial coefficient table corresponding to different voltage values ​​in the RF transmitter for storage. The pre-distortion coefficient group is used as the initial pre-distortion coefficient in the online mode of the RF predistorter, and its pre-distortion coefficient is adaptively updated on this basis to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages in the online mode.

[0045] Preferably, the output voltage of the step-up / step-down DC-DC converter is controlled by an analog voltage input thereto, the analog voltage is adjusted by a transmit branch gain setting in an RF transmitter, and the output voltage of the step-up / step-down DC-DC converter is used as a power supply voltage for a power amplifier during the next frame of transmission signal.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows: the system for adjusting the multi-level power supply voltage of a power amplifier based on the transmitter branch gain setting of the present invention is characterized in that the power supply voltage of the power amplifier is directly adjusted based on the transmitter branch gain setting range without measuring the average power of the power amplifier output signal within the next frame signal transmission time, because the relationship between the gain value setting of the transmission branch and the average power output of the power amplifier is obtained through actual measurement during the calibration stage and stored in the memory of the transmitter, so the amplifier power supply voltage is directly and automatically adjusted and set according to the transmission branch gain setting range and through a table lookup method without actual measurement, and the transmission branch gain setting is used to adjust the power size of the next frame of radio frequency transmission signal. When the average power of the output signal required by the power amplifier is small within the next frame signal transmission time, the transmission branch gain adjusts the power supply voltage of the power amplifier so that it is also reduced accordingly, so that the DC current is also reduced, and as a result, the redundant DC power consumption is reduced, the battery life is extended, and the energy or power efficiency of the power amplifier is improved. The power efficiency of the power amplifier can be further improved by adjusting the power supply voltage to reduce the redundant DC power consumption and simultaneously using a radio frequency predistorter to assist in the excitation of the power supply voltage of the power amplifier so as to compensate for the non-linear distortion generated by the amplifier output signal while maintaining a relatively large power output signal of the power amplifier.

[0047] The main application fields of the present invention are power amplifiers in base stations (BS) of 4th generation (4G) and 5th generation (5G) wireless communication networks, and power amplifiers in access points (AP) of wireless area networks (Wi-Fi). In these application system devices, the power consumption of the power amplifier accounts for about 60%-70% of the total system device consumption, so improving the power efficiency of the power amplifier plays a pivotal role in improving the power efficiency of the entire system.

[0048] The social, economic and environmental benefits of the present invention are to adjust the multi-level power supply voltage of the power amplifier based on the transmitter branch gain setting, so as to reduce the excess power supply DC power consumption, thereby improving the power amplifier power transmission efficiency, saving electricity operating costs, reducing carbon dioxide emissions in the atmosphere, and improving the green environment. This is because this excess DC power consumption will be converted into heat energy and dissipated into the atmosphere, increasing carbon dioxide emissions in the atmosphere, producing a greenhouse effect, and affecting environmental quality. Therefore, the technology of improving power transmission efficiency by reducing DC power consumption of the system equipment is also called green radio technology. Driven by the two important factors of economic considerations and environmental considerations, improving the power efficiency of the power amplifier is one of the most promising and active invention and innovation directions in many studies. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 A schematic diagram of the structure of an envelope and average power excitation (tracking) power amplifier system and digital predistortion (DPD) compensation in the prior art;

[0051] Figure 2 A schematic diagram of the structure of a radio frequency predistortion (RFPD) compensation in the prior art;

[0052] Figure 3 It is a structural schematic diagram of a transmission branch gain adjustment power amplifier multi-level power supply voltage and radio frequency pre-distortion (RFPD) compensation 100 in the first embodiment of the present invention;

[0053] Figure 4 It is a detailed structural diagram of a transmission branch gain adjustment power amplifier power supply voltage and a radio frequency predistortion (RFPD) compensation 600 in the second embodiment of the present invention;

[0054] Figure 5 A relationship table between the gain configuration generation of each circuit unit in the transmitting branch and the output power of the power amplifier;

[0055] Figure 6 Another detailed structural diagram of the transmission branch gain adjustment power amplifier power supply voltage and radio frequency predistortion (RFPD) compensation in the first embodiment of the present invention;

[0056] Figure 7 is the schematic diagram of the pre-distortion generator circuit;

[0057] Figure 8 The present invention proposes a waveform diagram for indirectly estimating the average power during the next frame transmission signal period (within a certain time period) and directly adjusting the power amplifier power supply voltage according to the setting of the transmission branch gain;

[0058] Fig. 9 It is a structural schematic diagram of obtaining a radio frequency predistortion (RFPD) coefficient 500 for a power amplifier operating at different power supply voltages in an offline mode, i.e., a non-operating mode, according to the present invention;

[0059] Fig.10 The present invention is a flow chart for obtaining radio frequency predistortion (RFPD) coefficients as initial values ​​for a power amplifier operating at different power supply voltages in an offline mode. DETAILED DESCRIPTION

[0060] 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 are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0061] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Example 1

[0063] The present invention discloses a system for adjusting a multi-level power supply voltage of a power amplifier based on a transmitter branch gain setting, such as Figure 3 As shown, the system 100 includes a power amplifier 116 , a radio frequency transceiver 170 , a radio frequency predistorter 150 , and a step-up / step-down DC-DC converter 112 .

[0064] For details (please refer to Figure 6 As shown), the RF transceiver 170 includes a RF transmitter 180 and a RF receiver 190, wherein the RF transmitter 180 is used to output a control analog voltage signal 108 to control a fixed power supply voltage in the output multi-level power supply voltage value of the boost / buck DC-DC converter 112 as the power supply voltage of the power amplifier 116, and output the RF excitation signal 160 to the RF predistorter 150 for predistortion processing.

[0065] The boost / buck DC-DC converter 112 is directly based on the setting of the transmission branch amplification gain region range output signal, and controls the boost / buck converter 112 to output a fixed power supply voltage in the corresponding multi-level power supply voltage value as the power supply voltage of the power amplifier 116. The RF transceiver 170 can program the amplification gain region range output signal. The output power supply voltage value is controlled by the transmission branch gain region range setting. The gain region and the region range where the average power value of the next frame of RF signal falls have a close correspondence. When the average power value of the next frame of RF signal output is relatively large, the power supply voltage is also relatively large. Conversely, the power supply voltage is relatively small.

[0066] like Figure 6 As shown, the RF predistorter 150 includes

[0067] The error signal generator 146 is used to receive the RF excitation signal 160 output by the RF transmitter 180, the branch feedforward RF output coupling signal 168 coupled by the second coupler 136, and the branch feedback RF signal 130 coupled by the RF amplified signal output by the power amplifier 116 through the first coupler 124, and obtain the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal after down-conversion and demodulation respectively, and generate an error signal according to the difference between them in the time domain or the nonlinear distortion characteristics in the frequency domain, such as adjacent channel leakage power (ACLR), and send it to the pre-distortion coefficient generator 142;

[0068] The pre-distortion coefficient generator 144 adaptively updates the pre-distortion coefficient according to the error signal, and updates the pre-distortion coefficient by repeatedly calculating the difference between the input RF coupling signal 168 and the feedback RF signal 130 in the time domain and substituting it into an iterative formula until the error signal decreases and converges, and sends it to the pre-distortion polynomial generator 142;

[0069] The predistortion polynomial generator 142, when the start signal 162 is at a high level, processes the baseband signal of the RF coupling signal 168 input before amplification after down-conversion, demodulation, and low-pass filtering according to the updated predistortion coefficient to obtain a nonlinear polynomial, which is sent to the predistortion generator 148. On the contrary, when the start signal 162 is at a low level, the predistortion polynomial generator 142 is in a non-working state.

[0070] The predistortion generator 148 performs predistortion processing on the RF excitation signal 160 according to the nonlinear polynomial to obtain a RF predistortion signal 128 , and sends the predistortion signal to the power amplifier 116 .

[0071] The power amplifier 116 receives the predistortion signal 128, and performs power amplification on the predistortion signal 128 to generate a power-amplified radio frequency amplified signal 120. In addition, the power amplifier 116 also feeds back a power-amplified radio frequency signal power strength indication analog signal (TSSI) 126 to the radio frequency transceiver 170. The signal is used to detect the strength of the radio frequency amplified signal of the current frame, and jointly determine the strength or size of the signal to be transmitted in the next frame according to the quality feedback information of the signal received by the remote user, so as to adjust the strength of the signal to be transmitted in the next frame by setting the corresponding amplification gain value of the transmission branch, and adjust the voltage value output by the step-up / step-down DC-DC converter 112 according to the area range of the amplification gain.

[0072] like Figure 6 FIG. 4 is a more detailed block diagram of a system for adjusting a multi-level power supply voltage of a power amplifier based on a transmitter branch gain setting.

[0073] The RF amplified signal output by the power amplifier 116 is processed by the duplexer 122 and sent to the transmitting antenna 114 for transmission. The RF signal received from the transmitting antenna 114 is processed by the duplexer 122 and amplified by the external low noise amplifier 134 and sent to the RF receiver 190 in the RF transceiver 170. After the RF amplified signal output by the power amplifier 116 passes through the first coupler 124, a small part of the feedback RF signal 130 is fed back to the RF predistorter 150, and at the same time, a part of the signal feedback RF is sent to the RF receiver in the RF transceiver 170 for down-conversion and demodulation. As another option that may replace the predistortion function generator, the advantage of doing so is that the RF transceiver 170 can be used in the transmission mode, while the RF receiver 190 is in an idle state for down-conversion and demodulation, thereby eliminating the down-converter, demodulator, and analog-to-digital converter 152 in the RF predistorter 150 to simplify the system design. The above selection is controlled by the start signal 162.

[0074] Specifically, the RF transceiver 170 includes a RF receiver 190, a digital signal processing unit 172 and a RF transmitter 180 connected in sequence, wherein the RF receiver 190 includes:

[0075] The internal low noise amplifier 199 is used to receive the radio frequency signal 138 sent by the external low noise amplifier 134, and further amplify the radio frequency signal and send it to the radio frequency switch 196;

[0076] The RF switch 196 is used to receive the RF signal sent by the internal low noise amplifier 199 and the feedback RF signal 130 sent by the coupler 124 and output it to the down converter 194;

[0077] The down converter 194 is used to receive the RF signal 138 or the feedback RF signal 130 after being selected by the RF switch 196, and at the same time receive the single frequency local carrier signal sent by the receiving local oscillator 198. After passing through the down converter 194, the baseband signal and the high-frequency harmonic signal are output to the receiving baseband 192. In the receiving baseband 192, the high-frequency harmonic signal is filtered out by the low-pass filter, and the low-frequency baseband signal is sent to the digital signal processing unit 172 through the low-pass filter.

[0078] The radio frequency transmitter 180 comprises:

[0079] The transmitting baseband 182 is used to receive the baseband signal processed by the digital signal processing unit 172, and perform digital-to-analog conversion, low-pass filtering to remove high-frequency harmonic signals, and digital-to-analog baseband signal amplification on the input digital baseband signal, and then send it to the up-converter 184;

[0080] The up-converter 184 uses the amplified analog baseband signal to multiply or modulate the carrier signal from the transmitting local oscillator 188 to perform up-conversion spectrum shifting into a radio frequency signal, and sends the radio frequency signal to the power amplifier driving unit 186;

[0081] The power amplifier driving unit 186 is used to power amplify the RF signal and use it as the output signal of the system transceiver 170. The output power driving signal of the power amplifier driving unit 186 is sent to the subsequent power amplifier 116 for further power amplification or first passes through the RF predistorter 150 for predistortion processing.

[0082] Figure 7 for Figure 6 The predistortion generator 148 is a more detailed circuit diagram, and the predistortion generator 148 includes a delay circuit 310 to implement a delay time τ1 so as to match the delay generated by the orthogonal RF modulator 320;

[0083] The orthogonal RF modulator 320 is composed of a delay circuit 330, an in-phase multiplier 340, an orthogonal multiplier 350, and an adder 360, wherein the delay circuit 330 generates a delay time τ2 to achieve a -90 degree phase shift, thereby forming an orthogonal branch RF signal; in the orthogonal RF modulator 320, the in-phase predistortion polynomial and the orthogonal predistortion polynomial are output signals of the polynomial generator 142, and are multiplied by the in-phase multiplier 340 and the orthogonal multiplier 350 respectively, and the multiplied outputs are added by the adder 360 and sent to the third coupler 166 for synthesis and addition.

[0084] The second coupler 136 couples out a small portion of the RF signal and sends it to the orthogonal RF modulator 320. The third coupler 166 combines the RF signal output by the adder 360 with the predistortion signal and adds them in the third coupler 166, and then sends them to the power amplifier 116 for power amplification.

[0085] Example 2

[0086] The present invention discloses a system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting, such as Figure 4 As shown, the device is described in offline mode, measuring the power value of the power amplifier output signal and calibrating the one-to-one relationship between the transmitter branch gain index and the average power value of the power amplifier output with the help of the power amplifier output transmit signal strength indication signal (TSSI) 126. The transmit signal strength indication signal (TSSI) 126 is a DC voltage of the radio frequency RF signal after rectification by the power detector, and its size is proportional to the strength of the radio frequency RF signal.

[0087] It should be noted that there is a difference between offline mode and online mode: offline mode means that the RF transceiver is in a non-working state, such as the device or system is in the factory parameter performance test and parameter calibration stage; while online mode means that the device or system is in working use, such as the device or system is in user use.

[0088] The power measuring unit 618 and the transmission signal strength model establishing unit 616 in the dotted box indicate that the unit only works and exists in the offline mode; a small part of the RF signal of the RF amplified signal 120 output by the power amplifier is fed back to the RF predistorter 150 after passing through the first coupler 124, and at the same time, the RF amplified signal 120 is sent to the power measuring unit 618, and the output end of the power measuring unit 618 is connected to the input end of the transmission signal strength model establishing unit 616, and the output end of the transmission signal strength model establishing unit 616 is connected to the input end of the transmission branch gain search unit 608 in the RF transmitter 180.

[0089] In the offline mode, the RF transceiver 170 Figure 4 and Figure 6 As shown, the transmitter branch gain index is calibrated, and the radio frequency transmitter includes:

[0090] An analog-to-digital converter (ADC) 602 is used to receive and convert the analog voltage signal 126 indicating the power strength of the radio frequency signal amplified by the power amplifier 116, and send the converted digital signal to the gain index control unit 604;

[0091] The gain index control unit 604 is used to calibrate the measured transmission power and the target power in an offline mode before the system equipment leaves the factory, so that the error between the two is less than a threshold value, and set the corresponding gain index as an output to control the transmission branch gain search unit 608 and the control index simplification unit 606 respectively;

[0092] The transmitting branch gain search unit 608 is used to receive the gain index output by the gain index control unit 604, allocate the power amplification factor or gain of each circuit in the transmitting branch circuit unit by looking up a table, and output a signal to set the corresponding power gain value of each circuit controlled by the transmitting branch circuit unit 614;

[0093] The transmitting branch circuit unit 614 is used to set the corresponding power gain value of each circuit according to the power amplification factor or gain of each circuit of the transmitting branch assigned by the transmitting branch gain search unit 608, so as to determine the power of the RF excitation signal at the input end of the RF predistorter; the transmitting branch circuit unit 614 includes a second digital-to-analog converter (DAC), an analog low-pass filter, an analog baseband signal amplifier, in-phase and quadrature branch modulators and a power amplifier driver, wherein the analog filter is located at the output end of the second digital-to-analog converter (DAC), and its function is to remove high-frequency components and smooth its input waveform to remove false high-frequency copies or "images"; the modulator uses the amplified input baseband signal to modulate the carrier signal, that is, multiply it, also known as frequency up-conversion, and the modulated signal realizes spectrum shifting, that is, the low-frequency spectrum is moved to the high-frequency spectrum, and the up-converter and the modulator are designed together to realize spectrum shifting; the RF power amplifier driver performs power amplification on the modulated signal to meet the input signal power requirement of the subsequent power amplifier, and the amplification gain of the amplifier driver is adjustable, and the output signal power of the power amplifier can be increased or decreased by adjustment.

[0094] The transmitting branch circuit unit 614 is mainly composed of analog circuits, including baseband signal and radio frequency signal circuits.

[0095] The control index simplification unit 606 is used to receive the gain index output by the gain index control unit 604, simplify the gain index to obtain a simplified control index, and send the simplified control index to the power supply voltage search unit 610;

[0096] The power supply voltage search unit 610 is used to find the corresponding power supply voltage value according to the received simplified gain index, and convert it into an analog voltage signal through a first digital-to-analog converter (DAC) 612 to control the step-up / step-down DC-DC converter 112 to output the corresponding multi-level power supply voltage as the power amplifier power supply voltage value.

[0097] The transmission branch gain setting is achieved by setting the amplification gain of each circuit in the transmission branch unit, and its purpose is to adjust the power of the RF amplified signal 120 output by the power amplifier 116. Figure 5A distribution relationship between the transmission branch gain index and the gain of each circuit unit is listed. The sum of the gain decibels (dB) of each circuit unit is equal to the gain decibel (dB) of the transmission branch. The output power of the power amplifier is equal to the input power decibel milliwatt of the low-pass filter plus the gain decibel of the transmission branch, plus the gain decibel of the power amplifier. For example, when the gain index h = 50, the output power of the power amplifier is equal to: P IN (dBm)+15(dB)+25(dB)=P IN +40(dBm).

[0098] In offline mode, the gain index calibration works as follows:

[0099] First, the power amplifier output target power decibel milliwatt (dBm) value is preset, and then the gain index control unit 604 sets the amplification gain index, which corresponds to the estimated transmission branch amplification gain value, and the amplification gain value is equal to the sum of the amplification gain decibel values ​​of each circuit in the transmission branch circuit unit 614. Figure 5 As shown. Then, the output gain index signal of the index control unit 604 is sent to the transmission branch gain search unit 608 to find out the pre-designed amplification gain allocation format of each circuit, and the gain allocation format is sent to the transmission branch circuit unit 614 to set the amplification gain value of each circuit unit. The above-mentioned amplification gain index setting is expected to obtain a difference between the measured power and the target power decibel milliwatt (dBm) at the output end of the power amplifier less than a specific threshold value, and vice versa, the gain index control unit 604 repeatedly adjusts the gain index h so that the difference between them is less than a specific threshold value.

[0100] The output voltage value of the step-up / step-down DC-DC converter 112 depends on the analog voltage signal input by the step-up / step-down DC-DC converter. The power supply voltage of the power amplifier is directly set or adjusted through the step-up / step-down DC-DC converter according to the area where the transmitter branch gain index is located, and is used as the power supply voltage of the power amplifier when transmitting the next frame of RF signal. The power supply voltage value is set before the next frame of transmission signal and is stable when the next frame of transmission signal is transmitted. In this way, the analog voltage signal can be corrected according to the number of area divisions of the control coefficient simplification unit 606 to meet the actual application requirements.

[0101] The relationship between the power amplifier power supply voltage setting value and the strength of the 802.11 wireless local area network radio frequency signal in each frame signal waveform is as follows: Figure 8As shown, the strength of each frame signal waveform is proportional to the average power of the frame signal. Ttx is the time for the RF transceiver 170 to transmit the frame signal to the user in the transmission mode, and Trx is the time for the RF transceiver 170 to receive the confirmation from the user that it has been received correctly in the reception mode. Figure 8 It can be seen that the power amplifier power supply voltage is set by the transmit branch gain (see Figure 5 ) is proportional to the average power of the power amplifier output signal, that is, as the average power value of each frame signal increases or decreases, the power supply voltage also increases or decreases. When the average power of each frame signal is reduced, the DC power consumption decreases as the power supply voltage decreases, thereby improving energy efficiency without causing RF signal distortion. This method of reducing DC power consumption by reducing excess DC power consumption and not causing RF signal distortion is because the power supply voltage has been set stable before the next frame signal is transmitted, and the voltage is of appropriate size, so it will not cause distortion of the transmission signal.

[0102] Before leaving the factory, the calibration of the relationship between the power size or strength of the power amplifier output signal and the transmitter branch gain index is carried out in an offline state. Three representative frequency points are selected within the transmission frequency bandwidth, namely the lowest, middle and highest channel center frequency points. The selection of the channel center frequency point is related to the bandwidth of the transmitted signal. First, the calibration of the relationship between the power size or strength of the power amplifier output signal and the transmitter branch gain index is carried out on the required transmission signal at the low-end channel center frequency point. The transmitter branch gain index is adjusted from small to large, and the power step is about 0.5 dB. The power of the power amplifier output signal is measured at each gain index setting, thereby recording the relationship between all gain indices and the measured power. Then repeat the above steps to calibrate the relationship between the power size of the power amplifier output signal and the transmitter branch gain index at the middle channel center frequency point and the highest channel center frequency point, and adjust the gain index at each frequency point until the error between the measured RF transmitter output power and the target power is ≤±1 dB.

[0103] The calibrated gain index is stored in the memory inside the RF transceiver and is used in the online working mode to set the transmission branch gain according to the required output power of the next frame by adjusting the gain index to achieve the required transmission power output. At the same time, the corresponding power supply voltage value is found according to the simplified gain index, and is converted into an analog voltage signal through a digital-to-analog converter to control the boost / buck DC-DC converter to output the corresponding voltage level as the power amplifier power supply voltage value.

[0104] like Fig. 9As shown, in the offline mode, Embodiment 1-2 of the present invention collects the input and output equivalent baseband signals of the power amplifier respectively, and extracts the RF predistortion coefficients of the power amplifier working under different power supply voltages.

[0105] The system includes a radio frequency signal generator 510, a step-up / step-down DC-DC controller 506, a step-up / step-down DC-DC converter 112, a power amplifier 116, an attenuator 514, a spectrum analyzer 516, and a computer 504. When the power amplifier outputs an equivalent baseband signal, the output end of the radio frequency signal generator 510 is connected to the power amplifier 116, the attenuator 514, the spectrum analyzer 516, and the computer 504 in sequence. When the power amplifier inputs an equivalent baseband signal, the output end of the radio frequency signal generator 510 is connected to the spectrum analyzer 516 and the computer 504 in sequence. The step-up / step-down DC-DC controller 506 outputs an analog voltage signal to control the output voltage of the step-up / step-down DC-DC converter 112, and the voltage is the power supply voltage of the power amplifier 118.

[0106] It should be noted here that the signal connected to the input end of the spectrum analyzer 516 through the solid line is used to collect the output signal data of the power amplifier 116, while the signal connected to the input end of the spectrum analyzer through the dotted line is used to collect the input signal data of the RF signal generator 510 as the input signal data of the power amplifier 116. These two different ways of connecting to the input end of the spectrum analyzer 516 will not be carried out at the same time, but are connected separately for collecting different signal data.

[0107] Among them, the RF signal generator 510 outputs a modulated RF signal of a specific application, which is used as the input signal of the power amplifier 116 and is amplified by the power amplifier. In order to reflect the nonlinear characteristics of the power amplifier, the input signal strength of the power amplifier should be strong enough to enable the power amplifier to work in the nonlinear region or close to the nonlinear region. The amplified RF signal is attenuated by the attenuator 514 and sent to the spectrum analyzer 516 for down-conversion processing, filtering processing, and demodulation processing, and finally the equivalent baseband signal of the RF signal output of the power amplifier is obtained, and output to the computer 504 for digital signal analysis and processing. This process is called power amplifier output signal acquisition.

[0108] Then, the output of the RF signal generator 510 is connected to the input of the spectrum analyzer 516 without passing through the power amplifier, and the down-conversion processing, filtering processing, and demodulation processing as described above are performed to finally obtain the power amplifier RF signal input equivalent baseband signal, and then the equivalent baseband signal is output to the computer 504 for digital signal analysis and processing. This process is called power amplifier input signal acquisition.

[0109] The collected input and output baseband signals are digitally processed by a computer. For example, the low sampling rate data is converted to an up-sampling rate by using an interpolation method, the input and output signals are cross-correlated in the time domain to align them, and the appropriate data length is cut. After that, the input and output data of equal length are substituted into a least square formula to solve the pre-distortion coefficient under the power supply voltage.

[0110] Next, the step-up / step-down DC-DC controller 506 adjusts the step-up / step-down DC-DC converter 112 to the next output power supply voltage, and repeats the above data acquisition process to solve the pre-distortion coefficient at the voltage, until all different pre-distortion coefficient groups under the excitation of a limited number of different voltage values ​​are solved respectively, and all different pre-distortion coefficient groups are stored in the pre-distortion coefficient search unit in the RF transceiver, for example Figure 3 and Figure 6 The predistortion coefficient generator 144 in the transmitter is used as an initial predistortion coefficient group under different voltage values. When the transceiver works in the online mode, the initial value of the corresponding predistortion coefficient group is read out according to the preset value of the power supply voltage, a predistortion polynomial is generated, and a radio frequency predistortion signal is generated through the predistorter.

[0111] In offline mode, the power amplifier works under different power supply voltage excitations. Fig.10 As shown and also refer to Fig. 9 ,The method of extracting the corresponding radio frequency pre-distortion (RFPD) coefficient as the initial coefficient value includes:

[0112] Step 810: The boost / buck controller 506 sets a finite number N of power supply voltages, and the i-th voltage value is vi=Vi, 1≤i≤N;

[0113] Step 820: If i=1, then the power supply voltage vi of the power amplifier is V CC , that is, the power supply voltage of the power amplifier is the first fixed voltage V of the traditional power amplifier CC , otherwise vi=Vi, 1≤i≤N, and then calculate the predistortion coefficient corresponding to the i-th voltage value;

[0114] Step 830: First, the OFDM radio frequency signal generated by the radio frequency signal generator is connected to the spectrum analyzer. The spectrum analyzer 516 performs frequency down-conversion, analog-to-digital conversion and demodulation on the input OFDM radio frequency signal. The processed baseband signal is used as the equivalent baseband signal of the power amplifier radio frequency input and is output to the computer.

[0115] Step 840: Then, the OFDM RF signal generated by the RF signal generator is output to the input end of the power amplifier 116 for power amplification processing. The amplified RF signal is sent to the spectrum analyzer 516 through the attenuator for frequency down-conversion, demodulation, and analog-to-digital conversion processing. The baseband signal after the analog-to-digital conversion processing is used as the equivalent baseband signal output by the power amplifier and output to the computer;

[0116] Step 850: After the computer performs digital signal processing on the collected RF input equivalent baseband signal and output equivalent baseband signal of the power amplifier, the predistortion polynomial coefficients are respectively substituted into the least squares formula to solve the predistortion polynomial coefficients. The predistortion polynomial coefficients are used as the initial coefficient group under the condition of vi=Vi under the condition of 1≤i≤N.

[0117] Step 860: Continue to calculate the predistortion coefficient corresponding to the i+1th voltage value, at this time i=i+1, determine whether i is greater than N, if i is less than N, continue to repeat steps 820-850; if i is greater than N, proceed to the next step;

[0118] Step 870: Store the predistortion coefficient groups corresponding to the i voltage values ​​at the solution into a polynomial coefficient table corresponding to different voltage values ​​in the RF transceiver for use as the predistortion initial coefficient group working in the online mode.

[0119] In the offline mode, after the power amplifier is operated under different power supply voltage excitations, the RF input equivalent baseband signal and the output equivalent baseband signal data of the power amplifier are collected and substituted into the least squares formula to solve the corresponding pre-distortion coefficient group. When the transmitter in the transceiver operates in the online mode, the gain area of ​​the next frame transmission signal size is set according to the transmission branch, and the power supply voltage of the power amplifier is adjusted accordingly, and the corresponding pre-distortion initial coefficient group is read from the lookup table data table in the transmitter, which is used to compensate for the nonlinear distortion generated by the power amplifier under the power supply voltage excitation. As described in the above step 870, the lookup table data table is specially set for storing the pre-distortion coefficient group.

[0120] like Figure 6 As shown, the process in which the RF predistorter 150 adaptively updates the predistortion coefficient in the online mode to compensate for the nonlinear distortion caused by the power amplifier 116 under different power supply voltages includes:

[0121] Step S1: the error signal generator 146 respectively collects the feedforward RF signal 168 coupled by the second coupler from the RF excitation signal output by the RF transceiver 170 and the feedback RF signal 130 coupled by the first coupler from the RF amplified signal output by the power amplifier 116, and generates an error signal by using the difference between the RF signal and the feedback RF signal in the time domain, or obtains the error signal according to the strength of the leakage signal outside the frequency band of the feedback RF signal in the frequency domain, and then substitutes the error signal into the adaptive algorithm to update the predistortion coefficient;

[0122] Step S2: sending the predistortion coefficient updated in step S1 to the predistortion polynomial generator 142 to generate a predistortion polynomial, and sending the predistortion polynomial to the predistortion generator 148, the predistortion polynomial includes an in-phase component and an orthogonal component polynomial, and both have nonlinear characteristics;

[0123] Step S3: In the predistortion generator, the in-phase component of the predistortion polynomial is multiplied by the in-phase signal of the input RF excitation signal, and the orthogonal component of the predistortion polynomial is multiplied by the orthogonal signal of the input RF excitation signal; then the results of the two calculations are added to generate the required RF predistortion signal.

[0124] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any way. At the same time, the present invention takes the radio frequency transceiver system in the IEEE 802.11 wireless local area network as an application example of the present invention, but is not limited to this system. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting, characterized in that: The system includes A radio frequency transceiver, the radio frequency transceiver comprising a radio frequency transmitter and a radio frequency receiver, wherein the radio frequency transmitter is used to output an analog voltage signal to control the output variable multi-level power supply voltage value of the step-up / step-down DC-DC converter as the power supply voltage of the power amplifier, and output a radio frequency excitation signal to the radio frequency predistorter for predistortion processing; A step-up / step-down DC-DC converter is used to receive an analog voltage signal output by a radio frequency transmitter, and convert an input DC voltage of the step-up / step-down DC-DC converter into a corresponding voltage value of a multi-level power supply voltage as an output voltage to provide a power supply voltage value to a power amplifier; The RF predistorter is used to receive the RF excitation signal output by the RF transmitter, perform predistortion processing on the RF excitation signal to obtain the RF predistortion signal, and output the RF predistortion signal to the power amplifier; it is also used to receive the RF amplified signal of the power amplifier through a branch feedback RF signal coupled by the first coupler, and receive the RF excitation signal output by the RF transmitter through a branch RF signal coupled by the second coupler; A power amplifier is used to receive a multi-level power supply voltage and a radio frequency predistortion signal, and amplify the radio frequency predistortion signal under different variable power supply voltages, and send the amplified radio frequency predistortion signal to the antenna as a radio frequency amplified signal, and a branch signal of the radio frequency amplified signal is coupled by a first coupler and then fed back to the radio frequency predistorter; a part of the signal in the branch signal is fed back to the radio frequency and sent to the radio frequency transceiver for down-conversion and demodulation processing; The radio frequency transmitter comprises An analog-to-digital converter, used for receiving and converting an analog signal indicating the power strength of the radio frequency signal amplified by the power amplifier, and sending the converted digital signal to the gain index control unit; The gain index control unit is used to calibrate the measured transmission power and the target power in an offline mode before the system leaves the factory, so that the error between the two is less than the threshold value, and set the corresponding gain index as the output to control the transmission branch gain search unit and the control index simplification unit respectively; The transmitting branch gain search unit is used to receive the gain index output by the gain index control unit, allocate the power gain or gain of each circuit in the transmitting branch circuit unit by looking up the table, and output a signal to set the corresponding power gain value or gain of each circuit controlled by the transmitting branch circuit unit; The transmitting branch circuit unit is used to set the corresponding power gain value of each circuit according to the power amplification factor or gain of each circuit of the transmitting branch assigned by the transmitting branch gain search unit, so as to determine the power of the RF excitation signal at the input end of the RF predistorter; A control index simplification unit is used to receive the gain index output by the gain index control unit, simplify it to obtain a simplified control index, and send it to the power supply voltage search unit; A power supply voltage search unit, used to find the corresponding power supply voltage value according to the received simplified gain index, and convert it into an analog voltage signal through a first digital-to-analog converter to control the step-up / step-down DC-DC converter to output a corresponding voltage level as the power supply voltage value of the power amplifier; The transmitting branch circuit unit includes a second digital-to-analog converter, an analog filter, an amplifier, a modulator, an up-converter and a radio frequency power amplifier driver; Among them, the second digital-to-analog converter converts the digital baseband signal into an analog baseband signal, the analog filter is located at the output end of the second digital-to-analog converter and is used to remove high-frequency components; the amplifier appropriately amplifies the filtered baseband signal, and its amplification gain is used as a part of the transmission branch gain; the modulator uses the amplified input baseband signal to modulate the carrier signal, and the modulated signal realizes spectrum shifting, that is, the low-frequency spectrum is moved to the high-frequency spectrum, and the up-converter and the modulator are designed together to realize spectrum shifting; the RF power amplifier driver performs power amplification on the modulated signal to meet the input signal power requirement of the subsequent power amplifier, and the power amplifier amplification gain is fixed, while the RF power amplifier driver amplification gain is adjustable, and the output signal power of the power amplifier can be increased or decreased by adjustment; The sum of the power gain decibels of the analog filter, amplifier, modulator, up-converter and RF power amplifier driver constitutes the transmission branch gain decibel, and the sum of the transmission branch gain decibel and the power amplifier gain jointly determines the output power of the power amplifier; The process of simplifying the gain index by the control index simplification unit includes: simplifying the gain index range into a number of limited areas in order of size, and setting a representative code for each area, the representative code of each area corresponds to the corresponding power amplifier output power value range, and providing the corresponding power supply voltage value to the power amplifier through the power supply voltage search unit, and the power supply voltage value indirectly sets the average power area size of the next frame transmission signal according to the representative code of the gain index area, so as to select a reasonable power supply voltage value to avoid using redundant and excessive power supply voltage values, thereby reducing the DC power consumption of the power amplifier and improving the power efficiency of the power amplifier; Wherein, the transmission branch gain setting is realized by setting the amplification gain of each circuit in the transmission branch unit; In offline mode, the gain index calibration works as follows: First, the power amplifier output target power decibel milliwatt value is preset, and then the gain index control unit is used to set the amplification gain index, the gain index corresponds to the estimated transmission branch amplification gain value, and the amplification gain value is equal to the sum of the amplification gain decibel values ​​of each circuit in the transmission branch circuit unit; then, the output gain index signal of the index control unit is sent to the transmission branch gain search unit to find out the pre-designed amplification gain allocation format of each circuit, and the gain allocation format is sent to the transmission branch circuit unit to set the amplification gain value of each circuit unit; Before leaving the factory, the calibration of the relationship between the power size or strength of the power amplifier output signal and the transmitter branch gain index is performed offline. Three representative frequency points are selected within the transmission frequency bandwidth, namely the lowest, middle and highest channel center frequency points. The selection of the channel center frequency point is related to the bandwidth of the transmitted signal; first, the low-end channel center frequency point is selected to calibrate the relationship between the power size or strength of the power amplifier output signal and the transmitter branch gain index for the required transmission signal, and the transmitter branch gain index is adjusted from small to large, with a power step of 0.5 dB. The power of the power amplifier output signal is measured at each gain index setting, thereby recording the relationship between all gain indices and the measured power; then repeat the above steps to calibrate the relationship between the power size of the power amplifier output signal and the transmitter branch gain index at the middle channel center frequency point and the highest channel center frequency point, and adjust the gain index at each frequency point until the error between the measured RF transmitter output power and the target power is ≤±1 dB.

2. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 1, characterized in that: The radio frequency predistorter comprises An error signal generator is used to receive a branch feedforward RF signal coupled by a second coupler from an RF excitation signal output by an RF transmitter and a branch feedback RF signal coupled by a first coupler from an RF amplified signal output by a power amplifier, and obtain an equivalent baseband signal of the feedforward RF signal and an equivalent baseband signal of the feedback RF signal through down-conversion and demodulation respectively, and generate an error signal according to the difference between the equivalent baseband signal of the input RF signal and the equivalent baseband signal of the feedback RF signal in the time domain or the frequency domain, and send the error signal to a predistortion coefficient generator; A predistortion coefficient generator adaptively updates the predistortion coefficient according to the error signal until the error signal decreases and converges, and sends it to the predistortion polynomial generator; The predistortion polynomial generator processes the baseband signal of the input feedforward RF signal after down-conversion, demodulation, and low-pass filtering according to the updated predistortion coefficient to obtain a nonlinear polynomial, which is sent to the predistortion generator; The predistortion generator processes the RF excitation signal according to the nonlinear polynomial to obtain a RF predistortion signal, which is sent to the power amplifier for power amplification.

3. The system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 1, characterized in that: The power supply voltage search unit directly sets or adjusts the power supply voltage of the power amplifier according to the area where the transmitter branch gain index is located through a step-up / step-down DC-DC converter, and is used as the power supply voltage of the power amplifier when transmitting the next frame of RF signal. The power supply voltage value is set before the next frame of transmission signal and is stable when the next frame of transmission signal is transmitted.

4. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 2, characterized in that: In the offline mode, the input signal and output signal of the power amplifier are respectively collected to obtain the corresponding RF predistortion coefficient as the initial predistortion coefficient in the online mode. Therefore, the system also includes a RF signal generator, a boost / buck DC-DC controller, an attenuator, a spectrum analyzer and a computer. The output end of the RF signal generator is connected to the power amplifier, the attenuator, the spectrum analyzer and the computer in sequence to collect the output signal of the power amplifier. The output end of the RF signal generator is also directly connected to the spectrum analyzer to collect the input signal of the power amplifier. The boost / buck DC-DC controller outputs an analog voltage signal to control the output voltage of the boost / buck DC-DC converter, and the voltage is the power supply voltage of the power amplifier.

5. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 4, characterized in that: In the offline mode, the RF signal generator outputs a modulated RF signal for a specific application. First, the modulated RF signal is output to a power amplifier for amplification. The amplified RF signal is attenuated by an attenuator and then sent to a spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal output of the power amplifier, and the equivalent baseband signal is sent to a computer. After that, the modulated RF signal is directly output to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal input of the power amplifier, and the equivalent baseband signal is sent to the computer. The computer digitizes the equivalent baseband signal of the RF signal output of the power amplifier and the equivalent baseband signal of the RF signal input of the power amplifier.

6. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 5, characterized in that: In an offline state, the computer collects the equivalent baseband signal output by the power amplifier radio frequency signal and the equivalent baseband signal input by the power amplifier radio frequency signal respectively, and substitutes the equivalent baseband signal into the least squares formula to obtain the pre-distortion coefficient, wherein the pre-distortion coefficient is an initial coefficient group corresponding to the power supply voltage value, and different power supply voltage values ​​correspond to different pre-distortion coefficient groups, thus generating different initial pre-distortion coefficient groups, and sending the pre-distortion coefficient groups corresponding to different power supply voltage values ​​to the polynomial coefficient table corresponding to different voltage values ​​in the radio frequency transmitter for storage, and the pre-distortion coefficient group is used as the initial pre-distortion coefficient in the online mode of the radio frequency pre-distorter, and the pre-distortion coefficient is adaptively updated on this basis, so as to compensate the nonlinear distortion caused by the power amplifier under different power supply voltages in the online mode.

7. A system for adjusting a multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to claim 6, characterized in that: The process of adaptively updating the predistortion coefficient of the RF predistorter in the online mode to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages includes: Step S1: the error signal generator collects the feedforward RF signal coupled by the second coupler of the RF excitation signal output by the RF transceiver and the feedback RF signal coupled by the first coupler of the RF amplified signal output by the power amplifier, and obtains the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal after down-conversion and demodulation respectively, and generates the error signal by using the difference between the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal in the time domain, or obtains the error signal according to the strength of the leakage signal outside the frequency band of the feedback RF signal in the frequency domain, and then substitutes the error signal into the adaptive algorithm to update the initial pre-distortion coefficient; Step S2: sending the predistortion coefficient updated in step S1 to a predistortion polynomial generator to generate a predistortion polynomial, sending the predistortion polynomial to the predistortion generator, the predistortion polynomial is a complex polynomial, which includes an in-phase component and an orthogonal component polynomial, and both have nonlinear characteristics; Step S3: In the predistortion generator, the in-phase component of the predistortion polynomial is multiplied by the in-phase signal of the input RF excitation signal, and the orthogonal component of the predistortion polynomial is multiplied by the orthogonal signal of the input RF excitation signal; then the results of the two calculations are added to generate the required RF predistortion signal.

8. A method for implementing the system for adjusting the multi-level power supply voltage of a power amplifier based on transmitter branch gain setting according to any one of claims 1 to 7, characterized in that: The method includes In the online mode, the control index simplification unit in the radio frequency transmitter simplifies the received gain index to obtain a simplified control index, and the power supply voltage search unit searches for the corresponding power supply voltage value according to the input simplified control index, and converts it into an analog voltage signal through the first digital-to-analog converter to control the output voltage level of the boost / buck DC-DC converter as the corresponding actual power supply voltage of the power amplifier in the next frame transmission power value range; The power amplifier works under different power supply voltages, and the corresponding initial pre-distortion coefficient of the RF pre-distorter is configured through the RF transceiver. The RF pre-distorter enters the initial pre-distortion coefficient adaptive adjustment stage to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages. The transmitting branch gain search unit in the RF transmitter allocates the received gain index to the power gain or gain of each circuit in the transmitting branch circuit unit by looking up the table. The transmitting branch circuit unit sets the corresponding power gain value of each circuit according to the allocated power gain or gain of each circuit of the transmitting branch, and determines the power of the RF excitation signal at the input end of the RF predistorter; The RF excitation signal output by the RF transmitter is sent to the RF predistorter through a branch feedforward RF output coupling signal coupled by the second coupler, and is processed by down-conversion and demodulation to obtain an equivalent baseband signal of the transmitter RF signal input and sent to the error signal generator. At the same time, the error signal generator also collects the RF amplification signal output by the power amplifier through a branch feedback RF signal coupled by the first coupler, and obtains an equivalent baseband signal of the RF signal output by the power amplifier through down-conversion and demodulation. The error signal is generated by using the difference between the baseband signal of the feedforward RF signal and the baseband signal of the feedback RF signal in the time domain, or the error is obtained according to the strength of the leakage signal outside the frequency band of the feedback RF signal in the frequency domain. signal, and then substitute the error signal into the adaptive algorithm to update the initial predistortion coefficient, and the updated predistortion coefficient is sent to the predistortion polynomial generator to generate a predistortion polynomial, which is a complex polynomial, and includes an in-phase component and an orthogonal component polynomial, and the predistortion polynomial is sent to the predistortion generator, and in the predistortion generator, the in-phase component of the predistortion polynomial is multiplied with the in-phase signal of the input RF excitation signal, and the orthogonal component of the predistortion polynomial is multiplied with the orthogonal signal of the input RF excitation signal; and then the results of the two calculations are added to generate the required RF predistortion signal, and the RF predistortion signal is sent to the power amplifier for amplification processing; or In the offline mode, the RF signal generator outputs a modulated RF signal for a specific application. First, the modulated RF signal is output to the power amplifier for amplification. The amplified RF signal is attenuated by the attenuator and then sent to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal output of the power amplifier, and sent to the computer. After that, the modulated RF signal is directly output to the spectrum analyzer for down-conversion processing, filtering processing, and demodulation processing to obtain an equivalent baseband signal of the RF signal input of the power amplifier, and sent to the computer. The computer compares the collected equivalent baseband signal output by the power amplifier RF signal with the power amplifier RF signal. The equivalent baseband signal of the amplifier RF signal input is substituted into the least squares formula to obtain the pre-distortion coefficient, which is the initial coefficient group under the corresponding power supply voltage value. Different power supply voltage values ​​correspond to different pre-distortion coefficient groups, and different initial pre-distortion coefficient groups are generated. The pre-distortion coefficient groups corresponding to different power supply voltage values ​​are sent to the polynomial coefficient table corresponding to different voltage values ​​in the RF transmitter for storage. The pre-distortion coefficient group is used as the initial pre-distortion coefficient in the online mode of the RF predistorter, and its pre-distortion coefficient is adaptively updated on this basis to compensate for the nonlinear distortion caused by the power amplifier under different power supply voltages in the online mode.

9. The method according to claim 8, characterized in that The output voltage of the step-up / step-down DC-DC converter is controlled by an analog voltage at its input, and the analog voltage is adjusted by a transmission branch gain setting in a radio frequency transmitter. The output voltage of the step-up / step-down DC-DC converter is used as a power supply voltage for a power amplifier during the next frame of transmission signal.

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