Pre-distortion calibration method and device for WiFi power amplifier

Abstract

The invention discloses a pre-distortion calibration method and device for a WiFi power amplifier, relates to the technical field of power amplifier pre-distortion calibration, and aims to solve the problem that an existing calibration method cannot ensure that each power amplifier is calibrated for an optimal compensation range. The method comprises the following steps: acquiring target input power and gain stepping of to-be-calibrated power amplifiers in the same batch; determining an initial gain of the transmitting channel according to the target input power; and performing digital predistortion compensation coefficient iteration training and calibration on each to-be-calibrated power amplifier according to the initial gain and the gain stepping to obtain a target compensation coefficient of each to-be-calibrated power amplifier. According to the pre-distortion calibration method for the WiFi power amplifier provided by the invention, each power amplifier can be ensured to obtain the coefficient of the optimal compensation range, and the compensation performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power amplifier predistortion calibration, and particularly to a method and device for predistortion calibration of a WiFi power amplifier. Background Art

[0002] Digital predistortion is a power amplifier linearization technology that preprocesses the signal to be transmitted in the digital domain to minimize the non-linear components of the power amplifier output signal after the preprocessed signal passes through the power amplifier, thereby improving system performance. During the signal preprocessing process, a pre-trained compensation coefficient is required to perform predistortion correction on the power amplifier. Currently, for batch power amplifiers, a fixed channel gain is usually used to determine the compensation coefficient. Since the linear ranges of each chip may vary, it is impossible to ensure that each power amplifier is calibrated for the optimal compensation range. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and device for predistortion calibration of a WiFi power amplifier, which are used to train the compensation coefficient of each power amplifier by iteratively adjusting the transmit channel gain, so as to ensure that each power amplifier obtains the coefficient within the optimal compensation range, thereby improving the compensation performance.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a method for predistortion calibration of a WiFi power amplifier, including:

[0006] Obtain the target input power and gain step of the power amplifiers to be calibrated in the same batch; the target input power is the input power corresponding to the 1 dB compression point of the power amplifier to be calibrated; the gain step gradually decreases as the number of adjustment times increases;

[0007] Determine the initial gain of the transmit channel according to the target input power;

[0008] Perform iterative training and calibration of the digital predistortion compensation coefficient for each power amplifier to be calibrated according to the initial gain and the gain step, and obtain the target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated.

[0009] Optionally, the performing iterative training and calibration of the digital predistortion compensation coefficient for each power amplifier to be calibrated according to the initial gain and the gain step, and obtaining the target compensation coefficient of each power amplifier to be calibrated includes:

[0010] For any one of the power amplifiers to be calibrated, adjust the transmit channel gain to the initial gain, perform training and calibration of the digital predistortion compensation coefficient for the power amplifier to be calibrated according to the initial gain, and obtain the first compensation coefficient and the first compensation performance corresponding to the initial gain;

[0011] Increase the gain of the transmission channel according to the corresponding gain step to obtain the second adjusted gain;

[0012] Perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the second adjusted gain, and obtain the second compensation coefficient and the second compensation performance corresponding to the second adjusted gain;

[0013] Determine the adjustment direction of the transmission channel gain according to the first compensation performance and the second compensation performance;

[0014] Adjust the gain of the transmission channel according to the adjustment direction and the corresponding gain step to obtain the third adjusted gain;

[0015] Perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the third adjusted gain, and obtain the third compensation coefficient and the third compensation performance corresponding to the third adjusted gain;

[0016] Determine the next adjustment direction of the transmission channel according to the third compensation performance and the second compensation performance, and perform the next digital pre-distortion compensation coefficient training and calibration according to the next adjustment direction until the convergence condition is reached. Determine the compensation coefficient corresponding to the maximum compensation performance as the target compensation coefficient; the convergence condition is that the corresponding gain step is less than or equal to the threshold value, or the training time reaches the preset time.

[0017] Optionally, the determining the adjustment direction of the transmission channel gain according to the first compensation performance and the second compensation performance includes:

[0018] Judge whether the second compensation performance is less than the first compensation performance. If it is less, the adjustment direction of the transmission channel gain is to decrease the corresponding gain step; if it is greater than or equal, the adjustment direction of the transmission channel gain is to increase the corresponding gain step.

[0019] Optionally, the gain step takes the preset gain step as the initial value and decreases in powers of 2 as the number of adjustments increases; the determining the initial gain of the transmission channel according to the target input power includes:

[0020] Calculate the average value and the standard deviation of the target input powers of all power amplifiers to be calibrated;

[0021] According to the formula:

[0022]

[0023] Calculate to obtain the initial gain;

[0024] where, H 0 is the initial gain, P is the average value of the target input powers, and σ is the standard deviation of the target input powers.

[0025] Optionally, the digital pre - distortion compensation coefficient training and calibration of the power amplifier to be calibrated according to the initial gain to obtain the first compensation coefficient and the first compensation performance corresponding to the initial gain include:

[0026] Send a training signal to the transmission channel adjusted to the initial gain; the training signal passes through the transmission channel, the power amplifier to be calibrated, the analog loop - back channel, and the analog - to - digital converter; the training signal includes N amplitude segments; N is a positive integer;

[0027] Collect the output signal of the analog - to - digital converter;

[0028] Perform DC compensation and time - delay alignment processing on the output signal to obtain a feedback signal;

[0029] Compare the feedback signal with a reference signal to obtain a comparison result, and determine the first compensation coefficient corresponding to the target amplitude point according to the comparison result; the target amplitude point is the endpoint of the amplitude segment;

[0030] Calibrate the power amplifier to be calibrated according to the first compensation coefficient to obtain a calibration signal;

[0031] Calculate the compensation residual corresponding to each amplitude point according to the calibration signal and the reference signal;

[0032] Determine the first compensation performance based on the compensation residual.

[0033] Optionally, the determining the first compensation performance based on the compensation residual includes:

[0034] Sort the compensation residuals corresponding to each amplitude point in descending order to obtain a compensation residual set;

[0035] Determine the target weight of each compensation residual;

[0036] According to the target weight, perform weighted summation on the first M compensation residuals in the compensation residual set to obtain a weighted summation result; M is a positive integer;

[0037] Determine the root - mean - square of the weighted summation result as the first compensation performance.

[0038] Optionally, the number of amplitude segments of the reference signal is less than the number of amplitude segments of the training signal, and the target amplitude point is the endpoint of the amplitude segment of the reference signal; the comparing the feedback signal with the reference signal to obtain a comparison result, and determining the first compensation coefficient corresponding to the target amplitude point according to the comparison result includes:

[0039] Determine the amplitude point to be decomposed in the feedback signal; the amplitude point to be decomposed is between two adjacent target amplitude points;

[0040] Decompose the amplitude value of the amplitude point to be decomposed onto the amplitude values of adjacent target amplitude points to obtain the target amplitude values of the feedback signal at the target amplitude points;

[0041] Calculate the difference between the target amplitude value and the amplitude value of the reference signal at the target amplitude point; the difference is the first compensation coefficient corresponding to the target amplitude point.

[0042] Optionally, the power amplifier to be calibrated includes multiple calibration levels; after determining the target compensation coefficient corresponding to any calibration level, determine the target compensation coefficient corresponding to the next calibration level until the determination of the target compensation coefficients for all calibration levels is completed; continue to determine the target compensation coefficient for the next power amplifier to be calibrated.

[0043] Optionally, the process of performing DC compensation and time delay alignment processing on the output signal to obtain the feedback signal includes:

[0044] Subtract the DC estimate from the output signal to obtain a DC compensation signal;

[0045] Adjust the time of each data point of the DC compensation signal according to the delay time to align the time of each data point of the DC compensation signal with the time of each data point of the reference signal to obtain the feedback signal.

[0046] Compared with the prior art, a pre-distortion calibration method for a WiFi power amplifier provided by the present invention includes obtaining the target input power and gain step of power amplifiers to be calibrated in the same batch; wherein, the target input power is the input power corresponding to the 1dB compression point of the power amplifier to be calibrated, which can ensure that the initial gain of the transmission channel determined according to the target input power can cover the upper edge of the linear region of the input power of all chips in this batch. At the same time, the gain step gradually decreases as the number of adjustments increases. By performing digital pre-distortion compensation coefficient iterative training and calibration on each power amplifier to be calibrated according to the initial gain and gain step, it can be ensured that each power amplifier in this batch can obtain the optimal target compensation coefficient, and the target compensation coefficient can ensure calibration of the optimal compensation range of the power amplifier.

[0047] In a second aspect, the present invention also provides a pre-distortion calibration device for a WiFi power amplifier, including:

[0048] A data acquisition module, configured to acquire the target input power and gain step of power amplifiers to be calibrated in the same batch; the target input power is the input power corresponding to the 1dB compression point of the power amplifier to be calibrated; the gain step gradually decreases as the number of adjustments increases;

[0049] An initial gain determination module, configured to determine the initial gain of the transmission channel according to the target input power;

[0050] A target compensation coefficient calculation module is used to perform iterative training and calibration of digital pre-distortion compensation coefficients for each power amplifier to be calibrated according to the initial gain and gain step, so as to obtain the target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated.

[0051] Compared with the prior art, the beneficial effects of a pre-distortion calibration device for a WiFi power amplifier provided by the present invention are the same as those of the pre-distortion calibration method for a WiFi power amplifier described in the above technical solution, and will not be elaborated here. Description of the Drawings

[0052] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0053] Figure 1 It is a flowchart of a pre-distortion calibration method for a WiFi power amplifier provided by the present invention;

[0054] Figure 2 It is a schematic diagram of a DPD coefficient training system provided by the present invention;

[0055] Figure 3 It is a flowchart of coefficient training and calibration for any power amplifier to be calibrated provided by the present invention;

[0056] Figure 4 It is a schematic diagram of the structure of a pre-distortion calibration device for a WiFi power amplifier provided by the present invention.

[0057] Reference Numerals in the Drawings:

[0058] 1 - Transmitting digital channel, 2 - Digital-to-analog converter, 3 - Transmitting analog channel, 4 - Power amplifier to be calibrated, 5 - Antenna, 6 - Coupling circuit, 7 - Analog loopback channel, 8 - Analog-to-digital converter, 9 - DPD coefficient calibration module, 91 - DC estimation module, 92 - DC compensation module, 93 - Loop delay estimation module, 94 - Delay alignment module, 95 - Coefficient calculation module, 96 - Coefficient storage module, 97 - Training signal generation module, 98 - DPD calibration control module. Detailed Embodiments

[0059] In order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish identical or similar items with basically the same functions and roles. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit their order. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity and execution order, and terms such as "first" and "second" do not necessarily limit being different from each other.

[0060] It should be noted that in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0061] In the present invention, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one (item)" or its similar expression refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or multiple.

[0062] There are mainly two ways to obtain the compensation coefficient. One is to update it in real time based on the service signal, which will be called the online method later; the other is to send a pre-designed waveform and collect the power amplifier output signal through the loopback channel, and obtain the DPD compensation coefficient based on the difference between the measured signal and the expected ideal output signal, which will be called the offline method later. For scenarios with low complexity or power-sensitive, the offline method is generally adopted. For the offline method, the coefficient training of digital pre-distortion can be carried out once when the chip is powered on. During the subsequent operation process, when the set conditions are met, it can also be restarted to complete the coefficient update. During the coefficient training or update process, an appropriate channel gain needs to be set to ensure that the input power of the power amplifier is appropriate, so that the obtained coefficient can compensate for the non-linear distortion of the power amplifier within the largest possible power range. The channel gain can be obtained according to the batch test results, and the small batch statistical results are uniformly applied to all chips, or obtained by individually testing each chip through methods such as ATE testing before leaving the factory. The former is not the best for each chip, and the latter significantly increases the chip cost.

[0063] To address the above problems, the present invention discloses a pre-distortion calibration method and device for a WiFi power amplifier. If the iterative control function is implemented in hardware, on the premise of increasing a part of the logic resources, it is ensured that the coefficients for obtaining the best compensation range are obtained for each chip, thereby improving the compensation performance; if the iterative control function is implemented in software, basically no additional hardware resources are added, and under the condition of increasing a certain software running time, it is ensured that the coefficients for obtaining the best compensation range are obtained for each chip, thereby improving the compensation performance. Next, it will be described in conjunction with the accompanying drawings.

[0064] See Figure 1 , the present invention provides a pre-distortion calibration method for a WiFi power amplifier, including the following steps:

[0065] Step S1: Obtain the target input power and gain step of the power amplifiers to be calibrated in the same batch;

[0066] Among them, the target input power is the input power corresponding to the 1dB compression point of the power amplifier to be calibrated;

[0067] The gain step gradually decreases as the number of adjustment times increases; the gain step can be set as needed. Exemplarily, the gain step takes the preset gain step as the initial value and decreases in powers of 2 as the number of adjustment times increases, or decreases by a fixed value as the number of adjustment times increases, for example, decreasing by 3dB each time.

[0068] Step S2: Determine the initial gain of the transmission channel according to the target input power;

[0069] Specifically, step 102 includes: calculating the average value and standard deviation of the target input powers of all power amplifiers to be calibrated;

[0070] According to the formula:

[0071]

[0072] The initial gain is calculated;

[0073] where H 0 is the initial gain, is the average value of the target input power, and σ is the standard deviation of the target input power.

[0074] The transmission channel includes a digital transmission channel and an analog transmission channel. The initial gain and the gain step are the average gain configurations of several channels such as the digital transmission channel and the analog transmission channel. The goal of setting the initial gain of each channel is to make the power amplifier input power have the maximum amplitude at the 1 dB compression point.

[0075] Step S3: Perform digital pre-distortion compensation coefficient iterative training and calibration on each power amplifier to be calibrated according to the initial gain and the gain step, and obtain the target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated;

[0076] Specifically, the gain configuration of the transmission channel takes the initial gain as the initial value, and increases or decreases the corresponding gain step successively; each power amplifier to be calibrated needs to traverse each gain configuration of the transmission channel, and perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated with the adjusted gain value of the transmission channel each time. The adjustment direction of the next transmission channel gain is determined according to the compensation performance after the current gain adjustment and the compensation performance after the previous gain adjustment. When the compensation performance after the current gain adjustment is greater than the compensation performance after the previous gain adjustment, the gain of the transmission channel is increased by the corresponding gain step. When the compensation performance after the current gain adjustment is less than or equal to the compensation performance after the previous gain adjustment, the gain of the transmission channel is decreased by the corresponding gain step.

[0077] The compensation performance can be the weighted root mean square of the difference between the reference signal and the maximum number of amplitude endpoints of the measured signal. The number of amplitude endpoints for calculation can be set according to requirements, such as 3, 4, 5, etc. The larger the amplitude, the larger the weight value, and the weight value of each amplitude endpoint can be obtained through small batch experiments.

[0078] According to the above method, for a pre-distortion calibration method of a WiFi power amplifier provided by the present invention, the obtained target input power is the input power corresponding to the 1 dB compression point of the power amplifier to be calibrated, which can ensure that the initial gain of the transmission channel determined according to the target input power can cover the upper edge of the linear region of the input power of all chips in this batch. At the same time, the gain step gradually decreases as the number of adjustments increases. For any power amplifier to be calibrated, digital pre-distortion compensation coefficient iterative training and calibration are performed on the power amplifier to be calibrated according to the initial gain and the gain step, which can ensure that the obtained target compensation coefficient can calibrate the best compensation range of this power amplifier; iteratively determine the target compensation coefficients of the next power amplifier to be calibrated until the target compensation coefficients for calibrating all power amplifiers to be calibrated are determined; it can ensure that all power amplifiers in this batch can obtain the best compensation coefficients, thereby ensuring that each power amplifier chip is calibrated for the best compensation range.

[0079] The above step S3 can be specifically implemented through the following steps:

[0080] Step S31: Adjust the transmission channel gain to the initial gain, perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the initial gain, and obtain the first compensation coefficient and the first compensation performance corresponding to the initial gain;

[0081] Step S32: Increase the transmission channel gain according to the corresponding gain step to obtain the second adjusted gain;

[0082] Step S33: Perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the second adjusted gain, and obtain the second compensation coefficient and the second compensation performance corresponding to the second adjusted gain;

[0083] Step S34: Determine the adjustment direction of the transmission channel gain according to the first compensation performance and the second compensation performance;

[0084] Specifically, judge whether the second compensation performance is less than the first compensation performance. If it is less, the adjustment direction of the transmission channel gain is to decrease the corresponding gain step; if it is greater than or equal, the adjustment direction of the transmission channel gain is to increase the corresponding gain step.

[0085] Step S35: Adjust the gain of the transmission channel according to the adjustment direction and the corresponding gain step to obtain the third adjusted gain;

[0086] Step S36: Perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the third adjusted gain, and obtain the third compensation coefficient and the third compensation performance corresponding to the third adjusted gain;

[0087] Step S37: Determine the next adjustment direction of the transmit channel according to the third compensation performance and the second compensation performance, and perform the next digital pre-distortion compensation coefficient training and calibration according to the next adjustment direction until the convergence condition is reached, and obtain a set of calibration results; the set of compensation coefficients includes the compensation coefficients and compensation performances corresponding to each adjustment of the gain; the convergence condition is that the corresponding gain step is less than or equal to the threshold value, or the training time reaches the preset time; the set of calibration results includes the first compensation coefficient, the first compensation performance, the second compensation coefficient, the second compensation performance, the third compensation coefficient, the third compensation performance, and the compensation coefficients and compensation performances corresponding to each subsequent adjustment.

[0088] Step S38: Determine the compensation coefficient corresponding to the maximum compensation performance in the set of calibration results as the target compensation coefficient;

[0089] For any power amplifier to be calibrated, execute Step S31 and Step S38.

[0090] Step S39: Complete the determination of the target compensation coefficients of all power amplifiers to be calibrated.

[0091] The steps for confirming the next adjustment direction each time are the same as those for determining the adjustment direction for the first time, that is, by judging whether the current compensation performance is less than the previous compensation performance. If the current compensation performance is less than the previous compensation performance, the next adjustment direction is to decrease the corresponding gain step. If the current compensation performance is greater than or equal to the previous compensation performance, the next adjustment direction is to increase the corresponding gain step.

[0092] From the above steps, it can be seen that the present invention uses the initial gain as the initial value, and iteratively adjusts the transmit channel by successively adjusting the corresponding gain step. The adjustment direction of the gain step follows a preset judgment rule, that is, when the compensation performance corresponding to the gain after the current adjustment is greater than the compensation performance corresponding to the gain after the previous adjustment, the corresponding gain step of the transmit channel is increased. When the compensation performance corresponding to the gain after the current adjustment is less than the compensation performance corresponding to the gain after the previous adjustment, the corresponding gain step of the transmit channel is decreased; since the gain of the transmit channel is adjusted from small to large, and because the gain step gradually decreases as the number of adjustments increases, it is possible to perform an appropriate small-step back-off of the channel gain under a high transmit channel gain configuration at the critical point of the DPD compensation ability, so as to determine the optimal transmit channel gain configuration. This transmit channel configuration can ensure that the best power amplifier input power range is covered at the limit of the DPD compensation ability.

[0093] In the above Step S3, the training and calibration of the digital pre-distortion compensation coefficients for the power amplifier can be completed by a DPD coefficient training system, such as Figure 2As shown, the DPD coefficient training system includes: a transmitting digital channel 1, a digital-to-analog converter 2, a transmitting analog channel 3, a power amplifier to be calibrated 4, an antenna 5, a coupling circuit 6, an analog loopback channel 7, an analog-to-digital converter 8, and a DPD coefficient calibration module 9. The DPD coefficient calibration module 9 includes a DC estimation module 91, a DC compensation module 92, a loop delay estimation module 93, a delay alignment module 94, a coefficient calculation module 95, a coefficient storage module 96, a training signal generation module 97, and a DPD calibration control module 98.

[0094] Specifically, the transmission digital channel 1 in the above structure is a general term for the digital signal processing module before the DAC through which the service signal passes. The transmission digital channel is used to pre-distort the amplitude of the input signal of the transmission digital channel according to the DPD compensation coefficient. After the pre-distorted signal passes through the power amplifier PA, the nonlinear effect introduced by the PA is minimized compared to the case without pre-distortion. The power at the PA input can be controlled by adjusting the digital gain or the analog gain before the PA.

[0095] The transmit analog channel 3 in the above structure refers to the general term for the analog modules involved after the DAC and before the power amplifier, including a multi-stage module calibration adjustment module. The power at the PA input can be controlled by adjusting the digital gain or the analog gain before the PA.

[0096] The power amplifier 4 to be calibrated in the above structure is the main provider of output power for the entire transmitting system. When its output power exceeds a certain limit, the nonlinear characteristics of the power amplifier will cause obvious signal distortion, significantly deteriorating indicators such as error vector amplitude and channel leakage ratio. The signal output by the power amplifier 4 to be calibrated is transmitted through the antenna 5.

[0097] The coupling circuit 6 in the above structure is used to feed part of the PA output energy into the analog loopback channel. The output energy is generally measured by a certain attenuation according to the loopback channel characteristics, such as an attenuation of 20 dB.

[0098] The analog loopback channel 7 in the above structure is a general term for the analog modules involved between the coupling circuit and the ADC, and is responsible for transmitting the PA output signal obtained by the coupling circuit to the ADC.

[0099] The analog-to-digital converter 8 in the above structure is used to convert analog signals into digital signals.

[0100] The DC estimation module 91 in the above structure completes the DC estimation function of the loopback channel. The DC estimation is performed under the conditions that the analog transmit channel is enabled, the loopback channel is enabled, and the transmit waveform is turned off or equivalent all-zero data is transmitted. The working mode of the DC estimation module can be: performing a DC estimation before each DPD coefficient training and update process; or, during the entire DPD coefficient adaptive calibration process, performing a DC estimation only at the initial stage. This module can adopt any algorithm that can accurately estimate the DC. For example, under the above channel configuration, the DC can be estimated by cumulative averaging over a certain period of time.

[0101] The DC compensation module 92 in the above structure is used to utilize the DC value output by the DC estimation to perform DC compensation on the input signal of the DC compensation module 92 during the calibration process.

[0102] The loop delay estimation module 93 in the above structure is used to complete the loop delay estimation function. The loop delay refers to the time delay of a specific data point in the training waveform from the output of the training signal waveform generation module through the transmit digital channel, DAC, transmit analog channel, PA, analog loopback channel, and ADC, etc., until the equivalent sample point enters the coefficient calculation module to participate in the coefficient calculation. This delay is expressed in the number of samples specified by the data sample rate when performing the coefficient calculation. Specifically, to ensure the accuracy of the delay estimation, the training signal waveform used for the delay estimation is generally a signal with good autocorrelation and a certain bandwidth, such as the m-sequence, Golay sequence, etc. The sequence length is determined according to factors such as the autocorrelation performance of the sequence and the channel noise performance.

[0103] The delay alignment module 94 in the above structure is used to adjust the alignment relationship between the reference signal and the received loopback waveform according to the propagation delay of the training waveform estimated by the loop delay estimation module, ensuring that the data points at the same position of the training waveform are aligned, so as to correctly obtain the non-linear information and calculate the compensation coefficient.

[0104] The coefficient calculation module 95 in the above structure is used to calculate the DPD compensation coefficient. The training method of the DPD compensation coefficient is related to the DPD compensation method. Generally, the DPD compensation coefficient is the difference between the actually measured output signal of the PA and the expected reference signal, and the compensation coefficient corresponding to a specific amplitude value is the difference between the reference signal and the actually measured output signal at this amplitude value.

[0105] To make the reference signal comparable to the measured output signal, an appropriate amplitude value is selected to align the amplitudes of the reference signal and the measured output signal. Specifically, one or both of the reference signal and the measured output signal are scaled at this amplitude position to make their amplitudes equal. The principle for selecting the amplitude value is that the distortion after passing through the PA is small enough. Considering the trade-off between complexity and compensation accuracy, generally, the signal amplitude at the PA input is segmented, and compensation coefficients are generated only for the amplitude values at the endpoints of these segments during training. These compensation coefficients are indexed by the sequence numbers of the amplitude segment endpoints. Therefore, during the DPD coefficient training process, an appropriate training waveform needs to be designed to cover the amplitude range to be compensated with a specific distribution. The training signals that can be used include multi-amplitude pseudo-random sequences, sine signals, ramp signals, etc., and their amplitude ranges cover the entire fixed-point bit width with a certain distribution. Under the condition of time delay alignment, it can be known which amplitude segment the currently processed data point falls into based on the position and amplitude of the data point in the reference signal, and the compensation coefficients of the corresponding segment endpoints are updated accordingly.

[0106] Furthermore, the number of amplitudes of the training waveform signal can be the same as the number of amplitude segments, and the amplitudes are taken at the endpoints of each segment. In this case, a single data point updates a single compensation coefficient. The number of amplitudes of the training waveform signal can also be greater than the number of amplitude segments. For a data point with a specific amplitude, this specific amplitude is expressed as an interpolation of the endpoints of several adjacent amplitude segments, and the amplitude of this measured data point is decomposed into the endpoints of these amplitude segments with the respective interpolation weights of these endpoints as weights, and then the update values of the compensation coefficients are calculated at these segment endpoints. For example, if 2-point linear interpolation is used, the amplitude value of this data point is decomposed into the endpoints of two adjacent amplitude segments, and then the update values of the compensation coefficients are calculated at these two segment endpoints.

[0107] After the coefficients are calculated and updated, they are stored in the coefficient storage module 96 for DPD compensation. Each time the coefficient calculation module 95 is started, all the compensation coefficients under a specific DPD gain gear are updated once, that is, a DPD coefficient training and update process is completed. Before the start of this process, various pre-configurations need to be completed, such as calibration parameters, digital, transmit channel gain configuration, loopback channel configuration, etc. During a DPD coefficient training and update process, the coefficient calculation module 95 needs to be started repeatedly several times. Before the next start, the previously updated DPD compensation coefficients need to be applied to the DPD compensation, that is, each start is based on the compensation residuals to iteratively accumulate the compensation coefficients, and the updated compensation coefficients are used for the update. The number of times the coefficient calculation module 95 needs to be started repeatedly can be configured statically or enabled dynamically according to a certain rule. For example, it is controlled according to the relationship between the mean square error of all amplitude points of the reference signal and the measured output signal and the set threshold.

[0108] The coefficient storage module 96 in the above structure: It is used to store the DPD compensation coefficients calculated by the coefficient calculation module 95. Generally, for each PA gain level, a set of independent DPD compensation coefficients is reserved; in practical applications, according to the differences in the non-linear characteristics between PA levels, the DPD compensation coefficients can be appropriately combined to reduce the number of sets.

[0109] The training signal generation module 97 in the above structure is used to generate various training waveforms required during the DPD coefficient training process. During the loop delay estimation stage, it generates training waveforms with good broadband autocorrelation characteristics, such as the aforementioned m-sequence, Golay sequence, etc. During the DPD coefficient calculation stage, it generates waveforms that can fully cover the amplitude range, such as the aforementioned pseudo-random sequence, sine signal, ramp signal, etc.

[0110] The DPD calibration control module 98 in the above structure: It is used to complete the control of the entire DPD coefficient training and calibration process. For the transmit channel gain after each adjustment, a DPD coefficient training and update process is performed once. The coefficients stored in the coefficient storage module are cleared first during each training and update process. One DPD coefficient training and update process is a whole and is implemented by hardware. The training and update processes under different transmit channel gains can be implemented in two forms. One is implemented by hardware. On the premise of increasing a part of the logic resources, it ensures obtaining the coefficients with the best compensation range for each chip, thereby improving the compensation performance. The other is implemented by software, which basically does not increase the hardware resources. Under the condition of increasing a certain software running time, it ensures obtaining the coefficients with the best compensation range for each chip, thereby improving the compensation performance.

[0111] Based on the above DPD coefficient training system, step S31 specifically includes the following steps:

[0112] Step S311: Send the training signal to the transmit channel adjusted to the initial gain; the training signal passes through the transmit channel, the power amplifier to be calibrated, the analog loopback channel, and the analog-to-digital converter; the training signal includes N amplitude segments; N is a positive integer;

[0113] Step S312: The DPD coefficient calibration module collects the output signal of the analog-to-digital converter; performs DC compensation and delay alignment processing on the output signal to obtain the feedback signal;

[0114] Specifically, subtract the DC estimate from the output signal to obtain the DC compensation signal;

[0115] Adjust the time of each data point of the DC compensation signal according to the delay time, so that the time of each data point of the DC compensation signal is aligned with the time of each data point of the reference signal to obtain the feedback signal. The delay time is the time delay from the start of generating the training signal to the calculation of the compensation coefficient.

[0116] The coefficient calculation module in step S313 compares the feedback signal with the reference signal to obtain a comparison result, and determines the first compensation coefficient corresponding to the target amplitude point according to the comparison result; the target amplitude point is the endpoint of the amplitude segment.

[0117] When the number of amplitude segments of the training signal is the same as that of the reference signal, the first compensation coefficient corresponding to each target amplitude point is determined by calculating the compensation residuals of the reference signal and the feedback signal at the target amplitude point.

[0118] When the number of amplitude segments of the reference signal is less than that of the training signal, the target amplitude point is the endpoint of the amplitude segment of the reference signal; step S313 is specifically: determining the amplitude point to be decomposed in the feedback signal; the amplitude point to be decomposed is located between two adjacent target amplitude points.

[0119] Decompose the amplitude value of the amplitude point to be decomposed onto the amplitude values of the adjacent target amplitude points to obtain the target amplitude value of the feedback signal at the target amplitude point.

[0120] Calculate the difference between the target amplitude value and the amplitude value of the reference signal at the target amplitude point; the difference is the first compensation coefficient corresponding to the target amplitude point.

[0121] Step S314: Calibrate the power amplifier to be calibrated according to the first compensation coefficient to obtain a calibration signal.

[0122] The calibration process is to input the calculated compensation coefficient into the transmit digital channel to perform DPD compensation on the input signal of the transmit digital channel. After the compensated signal passes through the digital-to-analog converter, the transmit analog channel, the power amplifier to be calibrated, the analog loopback channel, the analog-to-digital converter, the DC compensation module, and the delay alignment module, a calibration signal is output.

[0123] Step S315: Calculate the compensation residual corresponding to each amplitude point according to the calibration signal and the reference signal.

[0124] The compensation residual is the difference between the reference signal and the calibration signal corresponding to each amplitude point.

[0125] Step S316: Determine the first compensation performance based on the compensation residual.

[0126] Specifically, sort the compensation residuals corresponding to each amplitude point in descending order to obtain a compensation residual set; determine the target weight of each compensation residual; the larger the amplitude value at the amplitude point, the greater the target weight, and the specific target weight can be obtained through small-batch experiments. According to the target weight, perform weighted summation on the first M compensation residuals in the compensation residual set to obtain a weighted summation result; M is a positive integer, and M can be set as needed, for example, 3, 4, or 5; determine the root mean square of the weighted summation result as the first compensation performance.

[0127] After each adjustment of the gain, digital pre-distortion compensation coefficient training and calibration are performed on the power amplifier to be calibrated, and steps S311 to S316 are executed. It can be understood that the initial gain in the steps is replaced with the corresponding adjusted gain.

[0128] As an optional method, the power amplifier to be calibrated includes multiple calibration levels; after determining the target compensation coefficient corresponding to any calibration level, the determination of the target compensation coefficient corresponding to the next calibration level is performed until the determination of the target compensation coefficients of all calibration levels is completed; then, the determination of the target compensation coefficient of the next power amplifier to be calibrated is continued. Specifically, as Figure 3 shown, the steps for coefficient calibration of a batch of power amplifiers to be calibrated with multiple levels are as follows:

[0129] Step 1: Initialize the parameters and modules related to DPD coefficient calibration.

[0130] It mainly includes the configuration of calibration module parameters related to DPD coefficient calibration, the configuration of digital transmission and reception channels, and the configuration of analog transmission and loopback channels. The configuration of calibration module parameters initializes the calibration parameter configuration to ensure that the module can complete the DPD coefficient calibration work as expected. The configuration of the digital transmission channel ensures that the selected transmission waveform comes from the DPD coefficient calibration module, enables the DPD compensation module, and at the same time ensures that the signal is sent to the DAC as expected. The configuration of the digital reception channel ensures that the ADC output signal is sent into the DPD coefficient calibration module as expected. The analog transmission configuration ensures that the DAC works as expected and its output signal enters the power amplifier (PA) as expected, and the coupled circuit after the power amplifier (PA) feeds the signal into the analog loopback channel, and the coupled circuit works normally as expected. The configuration of the analog loopback channel ensures that the output signal of the coupled circuit enters the ADC with a certain intensity as expected, and the ADC works normally as expected. In addition, there are several gain adjustment modules in the digital transmission channel and the analog transmission channel. The initialization process also includes reasonable adjustment of these gain modules to ensure that the power sent to the power amplifier meets the expectations, that is, to ensure that this power value is the initial value of power traversal, and to ensure that the power amplifier (PA) level is the initial level to be calibrated.

[0131] Step 2: Set the power amplifier gain level: Set the power amplifier gain level to the level to be calibrated. The number of power amplifier levels to be traversed is determined by the number of power amplifier levels designed by the specific chip and the characteristics of the power amplifier. For example, for some power amplifier levels designed to output relatively small signal powers and not reaching the saturation region corresponding to that level, DPD compensation may not be performed for that level, and correspondingly, there is no need to obtain the corresponding DPD compensation coefficient.

[0132] Step 3: Determine the step size and direction of the gain adjustment of the transmission channel. The adjustment of the channel gain includes setting the initial gain value of power traversal and the channel gain values for subsequent traversals.

[0133] Step 4: Adjust the channel gain according to the designed step and direction;

[0134] Step 5: Channel DC estimation;

[0135] Step 6: Channel delay estimation;

[0136] Step 7: Calculate the DPD compensation coefficient;

[0137] Step 8: Evaluate the compensation performance of the obtained DPD compensation coefficient under the current channel gain configuration;

[0138] Apply the DPD compensation obtained in Step 7 to the calibration waveform. Specifically, start the transmit digital channel, analog transmit channel, and analog loopback channel, send out the calibration waveform of the calibration module, and after collecting it through the ADC via the loopback channel, send it into the DPD calibration module to calculate the difference between the reference signal and the measured signal at this time, so as to evaluate the compensation performance of this compensation coefficient. The compensation performance determines the subsequent calibration gain configuration and whether the calibration is completed.

[0139] Calculate the compensation performance in the DPD calibration module and determine whether the compensation performance meets the convergence condition. If the compensation performance meets the convergence condition, end the DPD compensation coefficient calibration process corresponding to the current PA gear and go to Step 9 to determine whether the DPD compensation coefficient calibration for all power amplifier gain gears is completed. If it does not meet the convergence condition, go to Step 3 to continue traversing the DPD coefficient calibration under different transmit channel gains.

[0140] Step 9: Determine whether the DPD compensation coefficient calibration for all power amplifier gain gears is completed. If it has been completed, go to Step 10; otherwise, go to Step 2 to configure the power amplifier gear to be calibrated and start a further calibration process.

[0141] Step 10: End the DPD compensation coefficient calibration.

[0142] The embodiments of the present invention can divide functional modules according to the above method examples. For example, each functional module can be corresponding to each function, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiments of the present invention is illustrative, only a logical function division, and there can be other division methods in actual implementation.

[0143] In the case of dividing each functional module corresponding to each function, Figure 4 shows a schematic structural diagram of a predistortion calibration device for a WiFi power amplifier provided by the present invention. As Figure 4 shown, the device includes:

[0144] A data acquisition module 401, configured to acquire the target input power and gain step of the power amplifier to be calibrated in the same batch; the target input power is the input power corresponding to the 1 dB compression point of the power amplifier to be calibrated; the gain step gradually decreases as the number of adjustment times increases;

[0145] An initial gain determination module 402, configured to determine the initial gain of the transmission channel according to the target input power;

[0146] A target compensation coefficient calculation module 403, which performs iterative training and calibration on the digital pre-distortion compensation coefficient for each power amplifier to be calibrated according to the initial gain and the gain step, and obtains the target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated.

[0147] Optionally, the target compensation coefficient calculation module 403 may include:

[0148] A first gain adjustment unit, configured to adjust the transmission channel gain to the initial gain, perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the initial gain, and obtain a first compensation coefficient and a first compensation performance corresponding to the initial gain;

[0149] A second gain adjustment unit, configured to increase the transmission channel gain according to the corresponding gain step to obtain a second adjusted gain;

[0150] A second coefficient training and calibration unit, configured to perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the second adjusted gain, and obtain a second compensation coefficient and a second compensation performance corresponding to the second adjusted gain;

[0151] A first adjustment direction determination unit, configured to determine the adjustment direction of the transmission channel gain according to the first compensation performance and the second compensation performance;

[0152] A third gain adjustment unit, configured to adjust the gain of the transmission channel according to the adjustment direction and the corresponding gain step to obtain a third adjusted gain;

[0153] A third coefficient training and calibration unit, configured to perform digital pre-distortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the third adjusted gain, and obtain a third compensation coefficient and a third compensation performance corresponding to the third adjusted gain;

[0154] The next adjustment direction determination unit is configured to determine the next adjustment direction of the transmission channel according to the third compensation performance and the second compensation performance, and perform the next digital pre-distortion compensation coefficient training and calibration according to the next adjustment direction until the convergence condition is reached, so as to obtain a set of calibration results; the compensation coefficient set includes the compensation coefficient and compensation performance corresponding to each adjustment of the gain; the convergence condition is that the corresponding gain step is less than or equal to the threshold value, or the training time reaches the preset time.

[0155] The iteration unit is configured to complete the determination of the target compensation coefficients of all power amplifiers to be calibrated.

[0156] Optionally, the first gain adjustment unit may specifically be configured to: determine whether the second compensation performance is less than the first compensation performance, if it is less, the adjustment direction of the transmission channel gain is to decrease the corresponding gain step; if it is greater than or equal to, the adjustment direction of the transmission channel gain is to increase the corresponding gain step.

[0157] Optionally, the gain step takes the preset gain step as the initial value and decreases in powers of 2 as the number of adjustments increases; the initial gain determination module 402 may specifically include:

[0158] The average value and standard deviation calculation unit is configured to calculate the average value and standard deviation of the target input powers of all power amplifiers to be calibrated.

[0159] The initial gain calculation unit is configured to calculate the initial gain according to the formula:

[0160]

[0161] to calculate the initial gain;

[0162] where H 0 is the initial gain, is the average value of the target input powers, and σ is the standard deviation of the target input powers.

[0163] Optionally, the first gain adjustment unit may specifically include:

[0164] The training signal sending sub-unit is configured to send a training signal to the transmission channel adjusted to the initial gain; the training signal passes through the transmission channel, the power amplifier to be calibrated, the analog loopback channel, and the analog-to-digital converter; the training signal includes N amplitude segments; N is a positive integer;

[0165] The acquisition sub-unit is configured to acquire the output signal of the analog-to-digital converter;

[0166] The DC compensation and time delay alignment sub-unit is configured to perform DC compensation and time delay alignment processing on the output signal to obtain a feedback signal;

[0167] A comparison subunit, configured to compare the feedback signal with a reference signal to obtain a comparison result, and determine a first compensation coefficient corresponding to a target amplitude point according to the comparison result; the target amplitude point is an endpoint of an amplitude segment.

[0168] A root calibration subunit, configured to calibrate the power amplifier to be calibrated according to the first compensation coefficient to obtain a calibration signal.

[0169] A compensation residual calculation subunit, configured to calculate a compensation residual corresponding to each amplitude point according to the calibration signal and the reference signal.

[0170] A first compensation performance calculation subunit, configured to determine a first compensation performance based on the compensation residual.

[0171] Optionally, the first compensation performance calculation subunit may specifically be configured to:

[0172] Sort the compensation residuals corresponding to each amplitude point in descending order to obtain a compensation residual set.

[0173] Determine a target weight for each compensation residual.

[0174] According to the target weights, perform weighted summation on the first M compensation residuals in the compensation residual set to obtain a weighted summation result; M is a positive integer.

[0175] Determine the root mean square of the weighted summation result as the first compensation performance.

[0176] Optionally, the number of amplitude segments of the reference signal is less than the number of amplitude segments of the training signal, and the target amplitude point is an endpoint of an amplitude segment of the reference signal; the comparison subunit may be configured to:

[0177] Determine an amplitude point to be decomposed in the feedback signal; the amplitude point to be decomposed is located between two adjacent target amplitude points.

[0178] Decompose the amplitude value of the amplitude point to be decomposed onto the amplitude values of the adjacent target amplitude points to obtain a target amplitude value of the feedback signal at the target amplitude point.

[0179] Calculate the difference between the target amplitude value and the amplitude value of the reference signal at the target amplitude point; the difference is the first compensation coefficient corresponding to the target amplitude point.

[0180] Optionally, the power amplifier to be calibrated includes multiple calibration levels; after determining the target compensation coefficient corresponding to any one calibration level, determine the target compensation coefficient corresponding to the next calibration level until the target compensation coefficients of all calibration levels are determined; then continue to determine the target compensation coefficient of the next power amplifier to be calibrated.

[0181] Optionally, the DC compensation and time delay alignment subunit may specifically be used for:

[0182] Subtracting the DC estimate from the output signal to obtain a DC compensation signal;

[0183] Adjusting the time of each data point of the DC compensation signal according to the delay time to align the time of each data point of the DC compensation signal with the time of each data point of the reference signal, thereby obtaining a feedback signal.

[0184] The above mainly introduces the solution provided by the embodiments of the present invention from the perspective of the interaction between various modules. It can be understood that, in order to implement the above functions, it includes the corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should easily realize that, combining the units and algorithm steps of each example described in the embodiments disclosed herein, the present invention can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the way of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0185] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are executed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a terminal, a user device, or other programmable devices. The computer program or instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or data center integrating one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it may also be an optical medium, such as a digital video disc (DVD); or it may be a semiconductor medium, such as a solid state drive (SSD).

[0186] Although the present invention has been described in connection with the various embodiments, however, in the process of implementing the claimed invention, those skilled in the art can understand and realize other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0187] Although the present invention has been described in connection with specific features and their embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and the drawings are merely exemplary illustrations of the invention defined by the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A predistortion calibration method for a WiFi power amplifier, characterized in that: include: Obtaining the target input power and gain step of the power amplifiers to be calibrated of the same batch; the target input power is the input power corresponding to the 1 dB compression point of the power amplifier to be calibrated; the gain step gradually decreases as the number of adjustments increases; Determining an initial gain of a transmitting channel according to the target input power; The digital predistortion compensation coefficient of each power amplifier to be calibrated is iteratively trained and calibrated according to the initial gain and gain step to obtain a target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated.

2. The predistortion calibration method of the WiFi power amplifier according to claim 1, characterized in that: The iterative training and calibration of the digital predistortion compensation coefficient of each power amplifier to be calibrated according to the initial gain and the gain step to obtain the target compensation coefficient of each power amplifier to be calibrated includes: For any one of the power amplifiers to be calibrated, adjusting the transmit channel gain to an initial gain, performing digital predistortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the initial gain, and obtaining a first compensation coefficient and a first compensation performance corresponding to the initial gain; The transmission channel gain is increased according to the corresponding gain step to obtain the second adjustment gain; Performing digital predistortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the second adjustment gain, to obtain a second compensation coefficient and a second compensation performance corresponding to the second adjustment gain; Determining an adjustment direction of the transmit channel gain according to the first compensation performance and the second compensation performance; The gain of the transmitting channel is adjusted according to the adjustment direction and the corresponding gain step to obtain a third adjustment gain; Performing digital predistortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the third adjustment gain, to obtain a third compensation coefficient and a third compensation performance corresponding to the third adjustment gain; Determine the next adjustment direction of the transmit channel according to the third compensation performance and the second compensation performance, and perform the next digital pre-distortion compensation coefficient training and calibration according to the next adjustment direction until a convergence condition is reached, and obtain a calibration result set; the calibration result set includes the compensation coefficient and compensation performance corresponding to each gain adjustment; the convergence condition is that the corresponding gain step is less than or equal to the threshold value, or the training time reaches a preset time; Determine the compensation coefficient corresponding to the maximum compensation performance in the calibration result set as the target compensation coefficient; Complete the determination of the target compensation coefficients of all power amplifiers to be calibrated.

3. The pre-distortion calibration method of the WiFi power amplifier according to claim 2, characterized in that: Determining the adjustment direction of the transmit channel gain according to the first compensation performance and the second compensation performance includes: Determine whether the second compensation performance is less than the first compensation performance. If so, the adjustment direction of the transmit channel gain is to reduce the corresponding gain step; if so, the adjustment direction of the transmit channel gain is to increase the corresponding gain step.

4. The pre-distortion calibration method of the WiFi power amplifier according to claim 1, characterized in that: The gain step takes a preset gain step as an initial value and decreases by a power of 2 as the number of adjustments increases; and determining the initial gain of the transmission channel according to the target input power includes: Calculate the average and standard deviation of the target input powers of all power amplifiers to be calibrated; According to the formula: Calculate the initial gain; Where H0 is the initial gain, is the mean value of the target input power, and σ is the standard deviation of the target input power.

5. The pre-distortion calibration method of the WiFi power amplifier according to claim 2, characterized in that: The performing digital predistortion compensation coefficient training and calibration on the power amplifier to be calibrated according to the initial gain to obtain a first compensation coefficient and a first compensation performance corresponding to the initial gain includes: Sending a training signal to a transmission channel adjusted to an initial gain; the training signal passes through the transmission channel, the power amplifier to be calibrated, the analog loopback channel, and the analog-to-digital converter; the training signal includes N amplitude segments; N is a positive integer; Collecting the output signal of the analog-to-digital converter; Performing DC compensation and time delay alignment processing on the output signal to obtain a feedback signal; Comparing the feedback signal with the reference signal to obtain a comparison result, and determining a first compensation coefficient corresponding to a target amplitude point according to the comparison result; the target amplitude point is an end point of the amplitude segment; Calibrate the power amplifier to be calibrated according to the first compensation coefficient to obtain a calibration signal; Calculating a compensation residual corresponding to each amplitude point according to the calibration signal and the reference signal; A first compensation performance is determined based on the compensation residual.

6. The pre-distortion calibration method for a WiFi power amplifier according to claim 5, characterized in that: The determining a first compensation performance based on the compensation residual comprises: Sort the compensation residuals corresponding to each amplitude point in descending order to obtain a compensation residual set; Determine the target weight for each compensation residual; According to the target weight, the first M compensation residuals in the compensation residual set are weighted and summed to obtain a weighted summation result; M is a positive integer; The root mean square of the weighted sum result is determined as the first compensation performance.

7. The pre-distortion calibration method for a WiFi power amplifier according to claim 5, characterized in that: The number of amplitude segments of the reference signal is smaller than the number of amplitude segments of the training signal, and the target amplitude point is an end point of the amplitude segment of the reference signal; The step of comparing the feedback signal with the reference signal to obtain a comparison result, and determining a first compensation coefficient corresponding to the target amplitude point according to the comparison result includes: Determine an amplitude point to be decomposed in the feedback signal; the amplitude point to be decomposed is located between two adjacent target amplitude points; Decomposing the amplitude value of the amplitude point to be decomposed into the amplitude value of the adjacent target amplitude point to obtain the target amplitude value of the feedback signal at the target amplitude point; The difference between the target amplitude value and the amplitude value of the reference signal at the target amplitude point is calculated; the difference is a first compensation coefficient corresponding to the target amplitude point.

8. The pre-distortion calibration method for a WiFi power amplifier according to claim 1, characterized in that: The power amplifier to be calibrated includes multiple gears to be calibrated; after determining the target compensation coefficient corresponding to any gear to be calibrated, determine the target compensation coefficient corresponding to the next gear to be calibrated until the determination of the target compensation coefficients of all gears to be calibrated is completed; continue to determine the target compensation coefficient of the next power amplifier to be calibrated.

9. The pre-distortion calibration method for a WiFi power amplifier according to claim 5, characterized in that: The performing DC compensation and delay alignment processing on the output signal to obtain a feedback signal comprises: subtracting a DC estimate from the output signal to obtain a DC compensation signal; The time of each data point of the DC compensation signal is adjusted according to the delay time, so that the time of each data point of the DC compensation signal is aligned with the time of each data point of the reference signal, thereby obtaining a feedback signal.

10. A pre-distortion calibration device for a WiFi power amplifier, characterized in that: include: A data acquisition module is used to acquire the target input power and gain step of the power amplifiers to be calibrated of the same batch; the target input power is the input power corresponding to the 1dB compression point of the power amplifier to be calibrated; the gain step gradually decreases as the number of adjustments increases; An initial gain determination module, used to determine the initial gain of the transmission channel according to the target input power; The target compensation coefficient calculation module is used to iteratively train and calibrate the digital predistortion compensation coefficient of each power amplifier to be calibrated according to the initial gain and gain step to obtain the target compensation coefficient of each power amplifier to be calibrated; the target compensation coefficient is used to calibrate the power amplifier to be calibrated.

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