WO2018157321A1 - 发射机及数字预失真校准方法 - Google Patents

发射机及数字预失真校准方法 Download PDF

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Publication number
WO2018157321A1
WO2018157321A1 PCT/CN2017/075278 CN2017075278W WO2018157321A1 WO 2018157321 A1 WO2018157321 A1 WO 2018157321A1 CN 2017075278 W CN2017075278 W CN 2017075278W WO 2018157321 A1 WO2018157321 A1 WO 2018157321A1
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WIPO (PCT)
Prior art keywords
signal
digital
dpd
analog
transmitter
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PCT/CN2017/075278
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English (en)
French (fr)
Inventor
谢尔盖巴胡林
多尔基克德米特里•安那托里维齐
霍树栋
石华平
Original Assignee
华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN201780047720.5A priority Critical patent/CN109565482B/zh
Priority to PCT/CN2017/075278 priority patent/WO2018157321A1/zh
Priority to EP17898490.2A priority patent/EP3531644B1/en
Publication of WO2018157321A1 publication Critical patent/WO2018157321A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
    • H03F1/3247—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits using feedback acting on predistortion circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/36—Modulator circuits; Transmitter circuits
    • H04L27/366—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator
    • H04L27/367—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion
    • H04L27/368—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion adaptive predistortion
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier

Definitions

  • the embodiments of the present invention relate to the field of communications technologies, and in particular, to a transmitter and a digital predistortion calibration method.
  • Digital Pre-Distortion (DPD) calibration technology is a common technique in transmitters.
  • the DPD calibration technique feeds the output signal of the power amplifier to the digital domain through a certain method, and then uses an adaptive algorithm to calculate the nonlinear characteristics of the output signal of the power amplifier. Finally, the signal is subjected to a certain method before the signal is converted from the digital domain to the analog domain.
  • the pre-processing makes the pre-processed signal approximately appear as a distortion-free characteristic with respect to the digital baseband signal after passing through the power amplifier, thereby obtaining a linear power amplifier output.
  • the feedback module in the transmitter is mainly used to implement signal sampling.
  • FIG. 1 is a feedback module 10 provided by the present application.
  • the power amplifier output signal sequentially passes through the attenuator 11 , the amplifier 12 , the mixer 13 , the attenuator 14 , the amplifier 15 , and the mixer of the feedback module.
  • the mixer 13 is configured to acquire a local oscillator signal (LO1), and frequency-modulate the received signal according to the LO1.
  • the mixer 16 is used to acquire LO2 and frequency-modulated the received signal according to the LO2.
  • the ADC can sample the signal.
  • the ADC 17 needs to sample the entire bandwidth occupied by the processed output signal of the power amplifier.
  • ADC17 needs to acquire signals within the [-2.5, +2.5] signal bandwidth.
  • the signal bandwidth of the processed amplifier output signal is greater than 100 MHz (Mega Hertz, MHz)
  • the nonlinear nature of the signal which in turn causes the signal calibration to be less accurate.
  • the application provides a transmitter and a digital predistortion calibration method. Therefore, the nonlinear characteristics of the output signal of the power amplifier can be accurately calculated, thereby solving the problem that the signal calibration is not accurate enough.
  • the application provides a transmitter, including:
  • the DPD is used to transmit digital baseband signals to the analog transmit module and the DPD feedback update module.
  • the analog transmitting module is configured to process the digital baseband signal into an analog signal, and send the processed analog signal to an antenna end and an analog feedback module connected to the analog transmitting module.
  • the analog feedback module is configured to receive the ith frequency control word sent by the DPD feedback update module, and determine, according to the ith frequency control word, the first center frequency of the ith frequency sweep and the ith subframe corresponding to the processed analog signal Phase information of the spectrum; performing the ith frequency sweep on the ith sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, to obtain a corresponding a first digital signal; and transmitting the first digital signal to the DPD feedback update module; wherein the i-th sweep is an analog feedback mode
  • the DPD feedback update module is configured to determine a second center frequency point according to the ith frequency control word, so that the first center frequency point and the second center frequency point are aligned; and the digital baseband signal is processed according to the second center frequency point to obtain a corresponding a second digital signal; calculating an error value of the first digital signal and the corresponding second digital signal; and determining a DPD coefficient according to the error value corresponding to the N times of the frequency sweep, and transmitting the DPD coefficient to the DPD.
  • the DPD is also used to calibrate the digital baseband signal based on the DPD coefficients and send the calibrated signal as a new digital baseband signal to the analog transmit module and the DPD feedback update module.
  • the beneficial effects of the present application are as follows: since the analog feedback module does not need to sample the entire bandwidth occupied by the processed analog signal, but performs segmented frequency sweeping, and then the DPD feedback update module performs corresponding stitching according to the result of the segmented frequency sweeping. To obtain the DPD coefficient. Therefore, the nonlinear characteristics of the output signal of the power amplifier can be accurately calculated, thereby solving the problem that the signal calibration is not accurate enough.
  • the analog transmitting module comprises: a digital to analog converter for converting the digital baseband signal into an analog baseband signal and transmitting the analog baseband signal to the first mixer.
  • the first local oscillator is configured to generate a local oscillator signal and send the local oscillator signal to the first mixer.
  • the first mixer is configured to frequency-modulate the analog baseband signal according to the local oscillator signal, and send the frequency-modulated analog signal to the amplifier.
  • the amplifier is configured to amplify the frequency-modulated analog signal to obtain a processed analog signal, and send the processed analog signal to an antenna and an analog feedback module connected to the analog transmitting module.
  • the present application provides a transmitter in which a specific structure of an analog transmitting module is provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • the analog feedback module includes: a second local oscillator, configured to receive the ith frequency control word sent by the DPD feedback update module; and determine the first center frequency point and the processed one according to the ith frequency control word
  • the phase information of the i-th sub-spectrum corresponding to the analog signal transmits the phase information of the first center frequency point and the ith sub-spectrum corresponding to the processed analog signal to the second mixer.
  • a second mixer configured to receive the processed analog signal, and perform, according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, the ith sub-spectrum corresponding to the processed analog signal.
  • the i-th sweep is performed to obtain a corresponding analog signal, and the corresponding analog signal is sent to the first filter.
  • the first filter is configured to filter the corresponding analog signal, and send the filtered analog signal to the analog to digital converter.
  • an analog-to-digital converter configured to convert the filtered analog signal into a first digital signal, and send the first digital signal to the DPD feedback update module.
  • the application provides a transmitter in which a specific structure of an analog feedback module is provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • the second mixer is specifically configured to: determine an i-th sub-spectrum according to phase information of the i-th sub-spectrum corresponding to the processed analog signal.
  • the i-th sub-spectrum is frequency-modulated according to the first center frequency.
  • the DPD feedback update module includes: a processor, configured to generate a second center frequency point according to the ith frequency control word, and send the second center frequency point to the transform unit.
  • a transform unit for receiving a digital baseband signal and performing a digital baseband signal according to a second center frequency point
  • the Fourier transform performs filtering processing on the Fourier transformed signal, performs Fourier transform on the filtered signal again to obtain a second digital signal, and sends the second digital signal to the adder.
  • an adder configured to calculate an error value of the first digital signal and the corresponding second digital signal; and send the error value corresponding to the N times of the frequency sweep to the processor.
  • the processor is further configured to determine the DPD coefficient according to the error value corresponding to the N times of the frequency sweep, and send the DPD coefficient to the DPD device.
  • the application provides a transmitter in which the specific structure and function of the DPD feedback update module are provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • the transform unit is specifically configured to:
  • x' i (k) represents the second digital signal corresponding to the i-th sweep in the k-th calculation of the DPD coefficient; x(k) represents the digital baseband in the k-th calculation of the DPD coefficient Signal; lpf represents a digital low-pass filter function; f i (k) represents a second center frequency point in the process of calculating the DPD coefficient at the kth time; k is a positive integer greater than or equal to 1.
  • the second digital signal can be accurately calculated.
  • the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • the transform unit comprises: a third mixer, a second filter, and a fourth mixer.
  • the third mixer is configured to receive the digital baseband signal, and perform Fourier transform on the digital baseband signal according to the second center frequency point to obtain a Fourier transformed signal.
  • a second filter is used to filter the Fourier transformed signal.
  • the fourth mixer is configured to perform Fourier transform on the filtered signal to obtain a second digital signal, and send the second digital signal to the adder.
  • the application provides a transmitter in which the specific structure of the transform unit is provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • the processor is specifically configured to:
  • the error value corresponding to the i-th sweep; f i (k) represents the second center frequency in the k-th calculation of the DPD coefficient, and k is a positive integer greater than or equal to 1.
  • a(k) represents the kth DPD coefficient
  • a(k-1) represents the k-1th DPD coefficient
  • a(0) 0
  • ⁇ represents an adaptive algorithm update step
  • the DPD coefficient can be accurately calculated.
  • the transmitter can accurately calculate the power amplifier The nonlinear characteristics of the output signal, which solves the problem of insufficient signal calibration.
  • a digital pre-distortion calibration method is provided, which can be performed by the above-mentioned transmitter, and its specific implementation process and beneficial effects are similar to those of the above embodiment, and are not described herein again.
  • the present application provides a digital predistortion calibration method, including:
  • the transmitter processes the digital baseband signal into an analog signal and outputs the processed analog signal to the antenna end of the transmitter.
  • phase information of the first center frequency point of the i-th frequency sweep and the i-th sub-spectrum corresponding to the processed analog signal is subjected to the i-th frequency sweep of the i-th sub-spectrum corresponding to the processed analog signal to obtain a corresponding first digital signal; wherein the i-th sweep is an analog feedback module
  • the transmitter determines a second center frequency point according to the ith frequency control word to align the first center frequency point and the second center frequency point; and processes the digital baseband signal according to the second center frequency point to obtain a corresponding second number signal.
  • the transmitter calculates an error value of the first digital signal and the corresponding second digital signal; and determines a DPD coefficient according to the error value corresponding to the N times of the frequency sweep; calibrates the digital baseband signal according to the DPD coefficient, and uses the calibrated signal as a new
  • the digital baseband signal uses the same processing as the digital baseband signal for the new digital baseband signal.
  • the transmitter processes the digital baseband signal into an analog signal, including:
  • the transmitter converts the digital baseband signal to an analog baseband signal.
  • the transmitter generates a local oscillator signal.
  • the transmitter frequency-modulates the analog baseband signal according to the local oscillator signal; and amplifies the frequency-modulated analog signal to obtain a processed analog signal.
  • the transmitter performs the ith frequency sweep on the i-th sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, to obtain a corresponding analog signal.
  • the transmitter performs filtering processing on the corresponding analog signal; and converts the filtered analog signal into a first digital signal.
  • the transmitter performs the ith frequency sweep on the ith sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, including:
  • the transmitter determines the i-th sub-spectrum according to the phase information of the i-th sub-spectrum corresponding to the processed analog signal.
  • processing the digital baseband signal according to the second center frequency to obtain a corresponding second digital signal including:
  • the transmitter performs Fourier transform on the digital baseband signal according to the second center frequency point, performs filtering processing on the Fourier transformed signal, and performs Fourier transform on the filtered signal to obtain a second digital signal.
  • the transmitter performs Fourier transform on the digital baseband signal according to the second center frequency point, performs filtering processing on the Fourier transformed signal, and performs Fourier transform on the filtered signal again to obtain a second Number Signals, including:
  • x' i (k) represents the second digital signal corresponding to the i-th sweep in the k-th calculation of the DPD coefficient
  • x(k) represents the digital baseband signal in the k-th calculation of the DPD coefficient
  • lpf represents A digital low-pass filter function
  • f i (k) represents a second center frequency point in the process of calculating the DPD coefficient at the kth time
  • k is a positive integer greater than or equal to 1.
  • the transmitter calculates an error value of the first digital signal and the corresponding second digital signal; and determines a DPD coefficient according to the error value corresponding to the N times of the frequency sweep, including:
  • Err(k) represents the total error value in the process of calculating the DPD coefficient at the kth time;
  • x' i (k) represents the second number corresponding to the i-th sweep in the k-th calculation of the DPD coefficient signal;
  • X i (k) represents the k-th calculation process DPD coefficients, the i-th frequency sweep corresponding to the first digital signal;
  • x 'i (k) -x i (k) represents the k-th calculating DPD coefficients
  • f i (k) represents the second center frequency in the process of calculating the DPD coefficient in the kth time, and k is a positive integer greater than or equal to 1;
  • a(k) represents the kth DPD coefficient
  • a(k-1) represents the k-1th DPD coefficient
  • a(0) 0
  • ⁇ represents an adaptive algorithm update step
  • the application provides a transmitter and a digital predistortion calibration method
  • the transmitter includes: a digital predistortion DPD device, an analog transmission module, an analog feedback module, and a DPD feedback update module.
  • the DPD is used to transmit digital baseband signals to the analog transmit module and the DPD feedback update module.
  • the analog transmitting module is configured to process the digital baseband signal into an analog signal, and send the processed analog signal to an antenna end and an analog feedback module connected to the analog transmitting module.
  • the analog feedback module is configured to receive the ith frequency control word sent by the DPD feedback update module, and determine, according to the ith frequency control word, the first center frequency of the ith frequency sweep and the ith subframe corresponding to the processed analog signal Phase information of the spectrum; performing the ith frequency sweep on the ith sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, to obtain a corresponding
  • the DPD feedback update module is configured to determine a second center frequency point according to the ith frequency control word, so that the first center frequency point and the second center frequency point are aligned; and the digital baseband signal is processed according to the second center frequency point to obtain a corresponding a second digital signal; calculating an error value of the first digital signal and the corresponding second digital signal; and determining a DPD coefficient according to the error value corresponding to the N times of the frequency sweep, and transmitting the DPD coefficient to the DPD.
  • the DPD is also used to calibrate the digital baseband signal based on the DPD coefficients and send the calibrated signal as a new digital baseband signal to the analog transmit module and the DPD feedback update module. Therefore, the nonlinear characteristics of the output signal of the power amplifier can be accurately calculated, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 1 is a schematic diagram of a feedback module provided by the present application.
  • FIG. 2 is a schematic diagram of a transmitter according to Embodiment 1 of the present application.
  • FIG. 3 is a schematic diagram of a transmitter according to Embodiment 2 of the present application.
  • FIG. 4 is a schematic diagram of a transmitter according to Embodiment 3 of the present application.
  • FIG. 5 is a schematic diagram of a transmitter according to Embodiment 4 of the present application.
  • FIG. 6 is a schematic diagram of a transmitter according to Embodiment 5 of the present application.
  • FIG. 7 is a schematic flowchart of a digital predistortion calibration method according to Embodiment 6 of the present application.
  • FIG. 8 is a schematic flowchart diagram of a digital predistortion calibration method according to Embodiment 7 of the present application.
  • the ADC in order to accurately calculate the nonlinear characteristic of the output signal of the power amplifier, the ADC needs to sample the entire bandwidth occupied by the processed output signal of the power amplifier.
  • the signal bandwidth is wide, it is difficult for the general model ADC to completely sample the entire bandwidth occupied by the signal, so that the nonlinear characteristics of the output signal of the power amplifier cannot be accurately calculated, thereby causing the problem that the signal calibration is not accurate enough.
  • the present application provides a transmitter.
  • the transmitter can be a transmitter of a network device or a user equipment.
  • the transmitter provided by the present application is applicable to systems such as mobile communication networks, fixed wireless access networks, wireless data transmission, and radar.
  • FIG. 2 is a schematic diagram of a transmitter according to Embodiment 1 of the present application.
  • the transmitter 20 includes a DPD device 21, an analog transmitting module 22, an analog feedback module 23, and a DPD feedback updating module 24; wherein the arrows in the figure indicate the direction of signal flow.
  • the DPD device 21 is configured to send a digital baseband signal to the analog transmitting module 22 and the DPD feedback updating module 24.
  • the analog transmitting module 22 is configured to process the digital baseband signal into an analog signal. And processing the processed analog signal to the antenna end connected to the analog transmitting module 22 and the analog feedback module 23.
  • the analog feedback module 23 is configured to receive the ith frequency control word sent by the DPD feedback update module 24. And determining, according to the ith frequency control word, phase information of the first center frequency point of the ith frequency sweep and the ith sub-spectrum corresponding to the processed analog signal. And performing the i-th frequency sweep on the i-th sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the i-th sub-spectrum corresponding to the processed analog signal, to obtain a corresponding The first digital signal. And transmitting the first digital signal to the DPD feedback update module 24.
  • the DPD feedback update module 24 is configured to determine a second center frequency point according to the ith frequency control word, so that the first center frequency point and the second center frequency point are aligned. Processing the digital baseband signal according to the second center frequency to obtain a corresponding second digital signal. Calculating an error value of the first digital signal and the corresponding second digital signal. And determining a DPD coefficient according to the error value corresponding to the N frequency sweeps, and transmitting the DPD coefficient to the DPD device 21.
  • the DPD 21 is further configured to calibrate the digital baseband signal according to the DPD coefficient.
  • the calibrated signal is sent to the analog transmit module 22 and the DPD feedback update module 24 as a new digital baseband signal.
  • the ith frequency control word may be used to indicate that the spectrum occupied by the processed analog signal is divided into N equal parts, and the ith frequency control word is a frequency control word corresponding to the ith sub-spectrum.
  • the analog feedback module 23 receives the ith frequency control word, and can determine the phase information of the ith sub-spectrum and the first center frequency corresponding to the ith sub-spectrum according to the bandwidth of the spectrum occupied by the processed analog signal.
  • the first frequency control word can be used to indicate that the spectrum occupied by the processed analog signal is divided into four equal parts, and the first frequency control word is the frequency control word corresponding to the first sub-spectrum.
  • the analog feedback module 23 determines that the bandwidth of the spectrum occupied by the processed analog signal is [-50 MHz, 50 MHz].
  • the analog feedback module 23 divides [-50 MHz, 50 MHz] into 4 equal parts according to the first frequency control word, which are [-50 MHz, -25 MHz], [-25 MHz, 0 MHz], [0 MHz, 25 MHz], and [25 MHz, respectively. 50MHz]. Since the first frequency control word is the frequency control word corresponding to the first sub-spectrum, the analog feedback module 23 can determine that the phase information of the first sub-spectrum is [-50 MHz, -25 MHz], and determine the first center of the first sub-spectrum. The frequency is -37.5MHz. The analog feedback module 23 can also calculate the phase information corresponding to the 2-4th sub-spectrum and the first center frequency corresponding to the 2-4th sub-spectrum respectively by the same method.
  • the ith frequency control word may be used to indicate that the spectrum occupied by the processed analog signal is divided into N sub-spectrals, wherein the bandwidth of the N sub-spectencies may constitute an arithmetic progression or a geometric sequence.
  • the i-th frequency control word is a frequency control word corresponding to the i-th sub-spectrum.
  • the spectrum occupied by the processed analog signals is composed of the N sub-spectrums, and there is no intersection between adjacent sub-spectrals.
  • the transmitter may store phase information for each sub-spectrum in a register.
  • N first digital signals will be obtained.
  • the first digital signal and the processed analog signal occupy a one-to-one correspondence of the sub-spectrums included in the spectrum.
  • the second center frequency point determined by the DPD feedback update module 24 according to the ith frequency control word is also the same as the first center frequency point, that is, the first center frequency point and the second center frequency point may be aligned.
  • the phase of the i-th sub-spectrum corresponding to the processed analog signal and the phase of the i-th sub-spectrum corresponding to the digital baseband signal determined by the DPD feedback update module 24 according to the i-th frequency control word are also the same. That is, the alignment of the phase of the i-th sub-spectrum corresponding to the processed analog signal and the phase of the i-th sub-spectrum corresponding to the digital baseband signal is implemented according to the ith frequency control word.
  • the DPD feedback update module 24 determines N corresponding second center frequency points respectively according to the first 1-N frequency control words. Based on this, the DPD feedback update module 24 processes the digital baseband signals according to the N second center frequency points to obtain N corresponding second digital signals. Finally, an error value of the first digital signal and the corresponding second digital signal is calculated. And determining a DPD coefficient according to the error value corresponding to the N frequency sweeps, and transmitting the DPD coefficient to the DPD device 21.
  • the DPD 21 is further configured to calibrate the digital baseband signal based on the DPD coefficients.
  • the calibrated signal is sent to the analog transmit module 22 and the DPD feedback update module 24 as a new digital baseband signal.
  • the processing method of the new digital baseband signal by the analog transmitting module 22 and the DPD feedback updating module 24 is exactly the same as the processing method of the above digital baseband signal.
  • the processing method of the analog signal by the analog feedback module 23 is also the same as that of the above processed
  • the processing method of the analog signal is exactly the same, and will not be described here.
  • the application provides a transmitter, wherein the analog feedback module can perform N sweeps on the processed analog signal Frequency, and get N corresponding first digital signals.
  • the DPD feedback update module can process the digital baseband signal to obtain a second digital signal.
  • the DPD feedback update module can calculate an error value of the first digital signal and the corresponding second digital signal. And determining the DPD coefficient according to the error value corresponding to the N frequency sweeps, so that the DPD device calibrates the digital baseband signal according to the DPD coefficient. Since the analog feedback module does not need to sample the entire bandwidth occupied by the processed analog signal, the segmentation frequency sweep is performed, and then the DPD feedback update module performs corresponding splicing according to the result of the segmentation frequency sweep to obtain the DPD coefficient. Therefore, the nonlinear characteristics of the output signal of the power amplifier can be accurately calculated, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 3 is a schematic diagram of a transmitter provided in Embodiment 2 of the present application.
  • the analog transmitting module 22 includes a digital to analog converter (DAC) 221, a first mixer 222, an amplifier 223, and a first local oscillator 224.
  • DAC digital to analog converter
  • the digital-to-analog converter 221 is configured to convert the digital baseband signal into an analog baseband signal, and send the analog baseband signal to the first mixer 222.
  • the first local oscillator 224 is configured to generate a local oscillator signal and send the local oscillator signal to the first mixer 222.
  • the first mixer 222 is configured to perform frequency modulation on the analog baseband signal according to the local oscillator signal, and send the frequency modulated analog signal to the amplifier 223.
  • the amplifier 223 is configured to amplify the frequency-modulated analog signal to obtain the processed analog signal, and send the processed analog signal to an antenna and a device connected to the analog transmitting module 22
  • the analog feedback module 23 is described.
  • the first mixer 222 is specifically configured to adjust the analog baseband signal from a low frequency to a high frequency according to the local oscillator signal.
  • the amplifier 223 can be further connected to a mixer, and the mixer can also be connected to a local oscillator to amplify the output of the amplifier 223 by the local oscillator signal generated by the local oscillator. Perform frequency tuning. And after the mixer, an amplifier can be connected, and the amplifier is used to amplify the frequency-modulated signal of the mixer.
  • the present application does not limit the number of amplifiers included in the transmitter and the number of local oscillators.
  • the present application provides a transmitter in which a specific structure of an analog transmitting module is provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 4 is a schematic diagram of a transmitter provided in Embodiment 3 of the present application.
  • the analog feedback module 23 includes a second local oscillator 231, a second mixer 232, a first filter 233, and an analog to digital converter ADC 234.
  • the second local oscillator 231 is configured to receive the ith frequency control word sent by the DPD feedback update module 24, and determine the first center frequency point according to the ith frequency control word The phase information of the i-th sub-spectrum corresponding to the processed analog signal, and transmitting the phase information of the first center frequency point and the ith sub-spectrum corresponding to the processed analog signal to the second mixer 232 .
  • the second mixer 232 is configured to receive the processed analog signal, and perform the processing according to the phase information of the first center frequency point and the ith sub-spectrum corresponding to the processed analog signal.
  • the i-th sub-spectrum corresponding to the subsequent analog signal performs the ith-th sweep, obtains a corresponding analog signal, and sends the corresponding analog signal to the first filter 233.
  • the first filter 233 is configured to perform filtering processing on the corresponding analog signal, and send the filtered analog signal to the analog-to-digital converter 234.
  • the analog-to-digital converter 234 is configured to convert the filtered analog signal into the first digital signal, and send the first digital signal to the DPD feedback update module 24.
  • the ith frequency control word may be used to indicate that the spectrum occupied by the processed analog signal is divided into N equal parts, and the ith frequency control word is a frequency control word corresponding to the ith sub-spectrum.
  • the second local oscillator 231 receives the ith frequency control word, and determines the phase information of the ith sub-spectrum and the first center frequency corresponding to the ith sub-spectrum according to the bandwidth of the spectrum occupied by the processed analog signal. .
  • the ith frequency control word may be used to indicate that the spectrum occupied by the processed analog signal is divided into N sub-spectrals, wherein the bandwidth of the N sub-spectencies may constitute an arithmetic progression or a geometric sequence.
  • the i-th frequency control word is a frequency control word corresponding to the i-th sub-spectrum.
  • the method in which the second local oscillator 231 determines the first center frequency according to the ith frequency control word may adopt the specific method steps described in the first embodiment. I will not repeat them here. And the second local oscillator 231 and the first local oscillator are based on the same reference information.
  • the analog feedback module 23 further includes: a register 235, wherein the register 235 is configured to store phase information of the 1-Nth sub-spectrum.
  • the second mixer 232 is specifically configured to: determine the i-th sub-spectrum according to phase information of an ith sub-spectrum corresponding to the processed analog signal.
  • the i-th sub-spectrum is frequency-modulated according to the first center frequency point.
  • the first filter 233 may perform filtering processing on the corresponding analog signal by using a low-pass filtering method in the prior art.
  • the application provides a transmitter in which a specific structure of an analog feedback module is provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 5 is a schematic diagram of a transmitter provided in Embodiment 4 of the present application.
  • the DPD feedback update module 24 includes a transform unit 241, a processor 242, and an adder 243.
  • the processor 242 is configured to generate a second center frequency point according to the ith frequency control word, and send the second center frequency point to the transform unit 241.
  • the transforming unit 241 is configured to receive the digital baseband signal, perform Fourier transform on the digital baseband signal according to the second center frequency point, perform filtering processing on the Fourier transformed signal, and perform filtering The processed signal is subjected to Fourier transform again to obtain the second digital signal; and the second digital signal is sent to the adder 243.
  • the adder 243 is configured to calculate an error value of the first digital signal and the corresponding second digital signal; The error value corresponding to the N frequency sweeps is sent to the processor 242.
  • the processor 242 is further configured to determine the DPD coefficient according to the error value corresponding to the N times of frequency sweeping, and send the DPD coefficient to the DPD device 241.
  • transform unit 241 is specifically configured to:
  • x' i (k) represents the second digital signal corresponding to the i-th sweep in the k-th calculation of the DPD coefficient; x(k) represents the process of calculating the DPD coefficient at the kth time
  • the digital baseband signal; lpf represents a digital low-pass filter function, which may be any digital low-pass filter function disclosed in the prior art, which is not limited in this application.
  • f i (k) represents the second center frequency point in the process of calculating the DPD coefficient at the kth time; k is the number of calculations of the DPD coefficient.
  • K is a positive integer greater than or equal to 1.
  • the application provides a transmitter in which the specific structure and function of the DPD feedback update module are provided. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 6 is a schematic diagram of a transmitter provided in Embodiment 5 of the present application.
  • the transform unit 241 includes a third mixer 2411, a second filter 2412, and a fourth mixer 2413.
  • the third mixer 2411 is configured to receive the digital baseband signal, and perform Fourier transform on the digital baseband signal according to the second center frequency point to obtain a Fourier transformed signal.
  • the second filter 2412 is configured to perform filtering processing on the Fourier transformed signal.
  • the fourth mixer 2413 is configured to perform Fourier transform on the filtered signal to obtain the second digital signal, and send the second digital signal to the adder 243.
  • the second filter 2412 can perform filtering processing using the digital low-pass filter function described above.
  • the processor 242 is specifically configured to:
  • Err(k) represents the total error value in the k-th calculation of the DPD coefficient
  • x' i (k) represents the corresponding i-th sweep in the k-th calculation of the DPD coefficient a second digital signal
  • x i (k) represents the first digital signal corresponding to the i-th sweep in the k-th calculation of the DPD coefficient
  • x' i (k)-x i ( k) represents the error value corresponding to the i-th sweep in the kth calculation of the DPD coefficient
  • f i (k) represents the first in the process of calculating the DPD coefficient at the kth time
  • the two center frequency points, k is a positive integer greater than or equal to 1.
  • a(k) represents the kth DPD coefficient
  • a(k-1) represents the k-1th DPD coefficient
  • a(0) 0
  • ⁇ represents an adaptive algorithm update step
  • the present application may use any adaptive algorithm provided by the prior art, which is not limited in this application.
  • the present application provides a transmitter in which the specific structure of the transform unit and the specific work of the processor are provided. can. Based on this, the transmitter can accurately calculate the nonlinear characteristics of the output signal of the power amplifier, thereby solving the problem that the signal calibration is not accurate enough.
  • FIG. 7 is a schematic flowchart diagram of a digital predistortion calibration method according to Embodiment 6 of the present application. As shown in FIG. 7, the method includes the following steps:
  • Step S701 The transmitter processes the digital baseband signal into an analog signal, and outputs the processed analog signal to the antenna end of the transmitter.
  • Step S702 The transmitter determines, according to the ith frequency control word, phase information of the first center frequency point of the ith frequency sweep and the ith sub-spectrum corresponding to the processed analog signal; and according to the first center frequency point and after processing The phase information of the i-th sub-spectrum corresponding to the analog signal is subjected to the ith-th sweep of the i-th sub-spectrum corresponding to the processed analog signal to obtain a corresponding first digital signal.
  • the spectrum includes the number of sub-spectra.
  • Step S703 The transmitter determines a second center frequency point according to the ith frequency control word, so that the first center frequency point and the second center frequency point are aligned; and processing the digital baseband signal according to the second center frequency point to obtain Corresponding second digital signal.
  • Step S704 The transmitter calculates an error value of the first digital signal and the corresponding second digital signal; and determines a DPD coefficient according to the error value corresponding to the N times of the frequency sweep; calibrates the digital baseband signal according to the DPD coefficient, and calibrates The latter signal acts as a new digital baseband signal, and the new digital baseband signal is treated the same as the digital baseband signal.
  • the present application provides a digital pre-distortion calibration method, which can be performed by the above-mentioned transmitter, and its specific implementation process and beneficial effects are similar to those of the foregoing embodiment, and are not described herein again.
  • FIG. 8 is a schematic flowchart diagram of a digital predistortion calibration method according to Embodiment 7 of the present application.
  • the foregoing step S701 specifically includes:
  • Step S701a The transmitter converts the digital baseband signal into an analog baseband signal
  • Step S701b The transmitter generates a local oscillator signal
  • Step S701c The transmitter performs frequency modulation on the analog baseband signal according to the local oscillator signal; amplifies the frequency-modulated analog signal to obtain a processed analog signal, and outputs the processed analog signal to the antenna end of the transmitter.
  • step S702 specifically includes:
  • Step S702a The transmitter determines, according to the ith frequency control word, phase information of the first center frequency point of the ith frequency sweep and the ith sub-spectrum corresponding to the processed analog signal;
  • Step S702b The transmitter performs the ith frequency sweep on the ith sub-spectrum corresponding to the processed analog signal according to the first center frequency point and the phase information of the ith sub-spectrum corresponding to the processed analog signal, to obtain a corresponding analog signal.
  • the step S702b specifically includes: determining, by the transmitter, the i-th sub-spectrum according to phase information of the i-th sub-spectrum corresponding to the processed analog signal.
  • the transmitter performs frequency modulation on the ith sub-spectrum according to the first center frequency to obtain a corresponding analog signal.
  • Step S702c The transmitter performs filtering processing on the corresponding analog signal; and converts the filtered analog signal into a first digital signal.
  • step S703 specifically includes:
  • Step S703a The transmitter determines a second center frequency point according to the ith frequency control word to align the first center frequency point and the second center frequency point.
  • Step S703b The transmitter performs Fourier transform on the digital baseband signal according to the second center frequency point, performs filtering processing on the Fourier transformed signal, and performs Fourier transform on the filtered signal again to obtain the first Two digital signals.
  • step S703b specifically includes:
  • x' i (k) represents the second digital signal corresponding to the i-th sweep in the k-th calculation of the DPD coefficient; x(k) represents the process of calculating the DPD coefficient at the kth time
  • the digital baseband signal; lpf represents a digital low-pass filter function; f i (k) represents the second center frequency point in the process of calculating the DPD coefficient at the kth time; k is a positive integer greater than or equal to 1 .
  • step S704 the transmitter calculates an error value of the first digital signal and the corresponding second digital signal, and determines a DPD coefficient according to the error value corresponding to the N times of the frequency sweep, including:
  • the transmitter passes the formula Calculate the total error value
  • a(k) represents the kth DPD coefficient
  • a(k-1) represents the k-1th DPD coefficient
  • a(0) 0
  • ⁇ represents an adaptive algorithm update step
  • the present application provides a digital pre-distortion calibration method, which can be performed by the above-mentioned transmitter, and its specific implementation process and beneficial effects are similar to those of the foregoing embodiment, and are not described herein again.

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Abstract

本申请提供一种发射机及数字预失真校准方法，其中发射机中的模拟反馈模块可以对处理后的模拟信号进行N次扫频，并得到N个对应的第一数字信号。DPD反馈更新模块可以对数字基带信号进行相应处理得到第二数字信号。最后DPD反馈更新模块可以计算第一数字信号和对应的第二数字信号的误差值。并根据N次扫频对应的误差值确定DPD系数，以使DPD器根据该DPD系数对数字基带信号进行校准。由于模拟反馈模块无需对处理后的模拟信号所占整个带宽进行采样，而是进行分段扫频，之后DPD反馈更新模块根据该分段扫频的结果进行相应的拼接，以获得DPD系数。从而可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。

Description

发射机及数字预失真校准方法 技术领域
本发明实施例涉及通信技术领域，尤其涉及一种发射机及数字预失真校准方法。
背景技术
数字预失真(Digital Pre-Distortion，DPD)校准技术是发射机中的常用技术。DPD校准技术是通过一定的方法将功放输出信号反馈到数字域，然后采用自适应的算法计算功放输出信号的非线性特性，最后在信号从数字域到模拟域变换之前采用一定的方法对信号进行预处理，使得预处理后的信号在经过功放后近似表现为相对于数字基带信号无失真的特性，从而获得线性的功放输出。
发射机中的反馈模块主要用于实现信号采样。以为计算功放输出信号的非线性特性做准备。例如图1为本申请提供的反馈模块10意图，如图1所示，其中功放输出信号依次经过反馈模块的衰减器11、放大器12、混频器13、衰减器14、放大器15、混频器16以及模数转换器(Analog to Digital Converter，ADC)17的处理，混频器13用于获取本振信号1(Local Oscillator，LO1)，并根据该LO1对接收到的信号进行调频。同样的，混频器16用于获取LO2，并根据该LO2对接收到的信号进行调频。ADC可以对信号进行采样。目前为了准确的计算功放输出信号的非线性特性，ADC17需要对经过处理后的功放输出信号所占的整个带宽进行采样。
例如：如图1所示，ADC17需要采集[-2.5，+2.5]信号带宽内的信号。然而当经过处理后的功放输出信号的信号带宽大于100兆赫(Mega Hertz，MHz)时，一般型号的ADC很难完整的对该信号所占的整个带宽进行信号采样，从而无法准确的计算功放输出信号的非线性特性，进而造成信号校准不够准确的问题。
发明内容
本申请提供一种发射机及数字预失真校准方法。从而可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
第一方面，本申请提供一种发射机，包括：
DPD器用于向模拟发射模块和DPD反馈更新模块发送数字基带信号。
模拟发射模块用于将数字基带信号处理为模拟信号，并将处理后的模拟信号发送给与模拟发射模块连接的天线端和模拟反馈模块。
模拟反馈模块用于接收DPD反馈更新模块发送的第i个频率控制字，并根据第i个频率控制字确定第i次扫频的第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息；根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号；并将第一数字信号发送给DPD反馈更新模块；其中第i次扫频为模拟反馈模 块对处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为处理后的模拟信号的频谱包括的子频谱的数目。
DPD反馈更新模块用于根据第i个频率控制字确定第二中心频点，以使第一中心频点和第二中心频点对齐；根据第二中心频点对数字基带信号进行处理，得到对应的第二数字信号；计算第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的误差值确定DPD系数，将DPD系数发送给DPD器。
DPD器还用于根据DPD系数对数字基带信号进行校准，并将校准后的信号作为新的数字基带信号发送给模拟发射模块和DPD反馈更新模块。
本申请的有益效果为：由于模拟反馈模块无需对处理后的模拟信号所占整个带宽进行采样，而是进行分段扫频，之后DPD反馈更新模块根据该分段扫频的结果进行相应的拼接，以获得DPD系数。从而可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，模拟发射模块包括：数模转换器，用于将数字基带信号转换为模拟基带信号，并将模拟基带信号发送给第一混频器。
第一本振振荡器，用于生成本振信号，并将本振信号发送给第一混频器。
第一混频器，用于根据本振信号对模拟基带信号进行调频，并将调频后的模拟信号发送给放大器。
放大器，用于对调频后的模拟信号进行放大，得到处理后的模拟信号，并将处理后的模拟信号发送给与模拟发射模块连接的天线和模拟反馈模块。
本申请提供一种发射机，其中提供了模拟发射模块的具体结构。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，模拟反馈模块包括：第二本振振荡器，用于接收DPD反馈更新模块发送的第i个频率控制字；并根据第i个频率控制字确定第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息，将第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息发送给第二混频器。
第二混频器，用于接收处理后的模拟信号，并根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的模拟信号，并将对应的模拟信号发送给第一滤波器。
第一滤波器，用于对对应的模拟信号进行滤波处理，将滤波处理后的模拟信号发送给模数转换器。
模数转换器，用于将滤波处理后的模拟信号转换为第一数字信号，将第一数字信号发送给DPD反馈更新模块。
本申请提供一种发射机，其中提供了模拟反馈模块的具体结构。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，第二混频器具体用于：根据处理后的模拟信号对应的第i个子频谱的相位信息确定第i个子频谱。根据第一中心频点对第i个子频谱进行调频。
可选地，DPD反馈更新模块包括：处理器，用于根据第i个频率控制字生成第二中心频点，并将第二中心频点发送给变换单元。
变换单元，用于接收数字基带信号，并根据第二中心频点对数字基带信号进行傅 里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到第二数字信号；并将第二数字信号发送给加法器。
加法器，用于计算第一数字信号和对应的第二数字信号的误差值；并将N次扫频对应的误差值发送给处理器。
处理器，还用于根据N次扫频对应的误差值确定DPD系数，并将DPD系数发送给DPD器。
本申请提供一种发射机，其中提供了DPD反馈更新模块的具体结构和功能。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，变换单元具体用于：
通过公式
Figure PCTCN2017075278-appb-000001
计算第二数字信号；
x'i(k)表示在第k次计算所述DPD系数过程中，第i次扫频对应的第二数字信号；x(k)表示在第k次计算所述DPD系数过程中的数字基带信号；lpf表示数字低通滤波函数；fi(k)表示在第k次计算DPD系数过程中的第二中心频点；k为大于等于1的正整数。
基于该公式可以准确的计算第二数字信号。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，变换单元包括：第三混频器、第二滤波器和第四混频器。
第三混频器，用于接收数字基带信号，并根据第二中心频点对数字基带信号进行傅里叶变换，得到傅里叶变换后的信号。
第二滤波器，用于对傅里叶变换后的信号进行滤波处理。
第四混频器，用于对滤波处理后的信号再次进行傅里叶变换，得到第二数字信号；并将第二数字信号发送给加法器。
本申请提供一种发射机，其中提供了变换单元的具体结构。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
可选地，处理器具体用于：
通过公式
Figure PCTCN2017075278-appb-000002
计算总误差值；
err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算DPD系数过程中，第i次扫频对应的第二数字信号；xi(k)表示在第k次计算DPD系数过程中，第i次扫频对应的第一数字信号；x'i(k)-xi(k)表示在第k次计算DPD系数过程中，第i次扫频对应的误差值；fi(k)表示在第k次计算DPD系数过程中的第二中心频点，k为大于等于1的正整数。
通过公式
Figure PCTCN2017075278-appb-000003
计算第k次的DPD系数。
a(k)表示第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
Figure PCTCN2017075278-appb-000004
表示xi(k)的共轭。
基于该公式可以准确的计算DPD系数。基于此，该发射机可以准确的计算功放 输出信号的非线性特性，进而解决信号校准不够准确的问题。
下面将提供一种数字预失真校准方法，该方法可由上述发射机执行，其具体的实现过程及有益下效果，与上述实施例类似，在此不再赘述。
第二方面，本申请提供一种数字预失真校准方法，包括：
发射机将数字基带信号处理为模拟信号，并将处理后的模拟信号输出至发射机的天线端。
发射机根据第i个频率控制字确定第i次扫频的第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息；并根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的第一数字信号；其中第i次扫频为模拟反馈模块对处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为处理后的模拟信号的频谱包括的子频谱的数目。
发射机根据第i个频率控制字确定第二中心频点，以使第一中心频点和第二中心频点对齐；根据第二中心频点对数字基带信号进行处理，得到对应的第二数字信号。
发射机计算第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的误差值确定DPD系数；根据DPD系数对数字基带信号进行校准，并将校准后的信号作为新的数字基带信号，对新的数字基带信号采用与数字基带信号相同的处理。
可选地，发射机将数字基带信号处理为模拟信号，包括：
发射机将数字基带信号转换为模拟基带信号。
发射机生成本振信号。
发射机根据本振信号对模拟基带信号进行调频；对调频后的模拟信号进行放大，得到处理后的模拟信号。
可选地，根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的第一数字信号，包括：
发射机根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的模拟信号。
发射机对对应的模拟信号进行滤波处理；将滤波处理后的模拟信号转换为第一数字信号。
可选地，发射机根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，包括：
发射机根据处理后的模拟信号对应的第i个子频谱的相位信息确定第i个子频谱。
发射机根据第一中心频点对第i个子频谱进行调频。
可选地，根据所述第二中心频点对所述数字基带信号进行处理，得到对应的第二数字信号，包括；
发射机根据第二中心频点对数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到第二数字信号。
可选地，发射机根据第二中心频点对数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到第二数字 信号，包括：
发射机通过公式
Figure PCTCN2017075278-appb-000005
计算第二数字信号；
x'i(k)表示在第k次计算DPD系数过程中，第i次扫频对应的第二数字信号；x(k)表示在第k次计算DPD系数过程中的数字基带信号；lpf表示数字低通滤波函数；fi(k)表示在第k次计算DPD系数过程中的第二中心频点；k为大于等于1的正整数。
可选地，发射机计算第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的误差值确定DPD系数，包括：
发射机通过公式
Figure PCTCN2017075278-appb-000006
计算总误差值；
err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算DPD系数过程中，第i次扫频对应的所述第二数字信号；xi(k)表示在第k次计算DPD系数过程中，第i次扫频对应的第一数字信号；x'i(k)-xi(k)表示在第k次计算DPD系数过程中，第i次扫频对应的误差值；fi(k)表示在第k次计算DPD系数过程中的第二中心频点，k为大于等于1的正整数；
发射机通过公式
Figure PCTCN2017075278-appb-000007
计算第k次的DPD系数；
a(k)表示第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
Figure PCTCN2017075278-appb-000008
表示xi(k)的共轭。
本申请提供一种发射机及数字预失真校准方法，该发射机包括：数字预失真DPD器、模拟发射模块、模拟反馈模块和DPD反馈更新模块。DPD器用于向模拟发射模块和DPD反馈更新模块发送数字基带信号。模拟发射模块用于将数字基带信号处理为模拟信号，并将处理后的模拟信号发送给与模拟发射模块连接的天线端和模拟反馈模块。模拟反馈模块用于接收DPD反馈更新模块发送的第i个频率控制字，并根据第i个频率控制字确定第i次扫频的第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息；根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号；并将第一数字信号发送给DPD反馈更新模块；其中第i次扫频为模拟反馈模块对处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为处理后的模拟信号的频谱包括的子频谱的数目。DPD反馈更新模块用于根据第i个频率控制字确定第二中心频点，以使第一中心频点和第二中心频点对齐；根据第二中心频点对数字基带信号进行处理，得到对应的第二数字信号；计算第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的误差值确定DPD系数，将DPD系数发送给DPD器。DPD器还用于根据DPD系数对数字基带信号进行校准，并将校准后的信号作为新的数字基带信号发送给模拟发射模块和DPD反馈更新模块。从而可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
附图说明
图1为本申请提供的反馈模块的示意图；
图2为本申请实施例一提供的发射机的示意图；
图3为本申请实施例二提供的发射机的示意图；
图4为本申请实施例三提供的发射机的示意图；
图5为本申请实施例四提供的发射机的示意图；
图6为本申请实施例五提供的发射机的示意图；
图7为本申请实施例六提供的一种数字预失真校准方法的流程示意图；
图8为本申请实施例七提供的一种数字预失真校准方法的流程示意图。
具体实施方式
现有技术中为了准确的计算功放输出信号的非线性特性，ADC需要对经过处理后的功放输出信号所占的整个带宽进行采样。然而当信号带宽较宽时，一般型号的ADC很难完整的该信号所占的整个带宽进行信号采样，从而无法准确的计算功放输出信号的非线性特性，进而造成信号校准不够准确的问题。为了解决这一技术问题，本申请提供一种发射机。其中该发射机可以为网络设备或者用户设备的发射机。本申请提供的发射机适用于移动通信网络、固定无线接入网、无线数据传输及雷达等系统中。
实施例一
图2为本申请实施例一提供的发射机的示意图。如图2所示，该发射机20包括：DPD器21、模拟发射模块22、模拟反馈模块23和DPD反馈更新模块24；其中图中的箭头表示信号流方向。
所述DPD器21用于向所述模拟发射模块22和所述DPD反馈更新模块24发送数字基带信号。
所述模拟发射模块22用于将所述数字基带信号处理为模拟信号。并将处理后的模拟信号发送给与所述模拟发射模块22连接的天线端和所述模拟反馈模块23。
所述模拟反馈模块23用于接收所述DPD反馈更新模块24发送的第i个频率控制字。并根据所述第i个频率控制字确定第i次扫频的第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息。根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号。并将所述第一数字信号发送给所述DPD反馈更新模块24。其中所述第i次扫频为所述模拟反馈模块对所述处理后的模拟信号对应的第i个子频谱的扫频。i＝1，2……N，N为所述处理后的模拟信号的频谱包括的子频谱的数目。
所述DPD反馈更新模块24用于根据所述第i个频率控制字确定第二中心频点，以使所述第一中心频点和所述第二中心频点对齐。根据所述第二中心频点对所述数字基带信号进行处理，得到对应的第二数字信号。计算所述第一数字信号和对应的第二数字信号的误差值。并根据N次扫频对应的所述误差值确定DPD系数，将所述DPD系数发送给所述DPD器21。
所述DPD器21还用于根据所述DPD系数对所述数字基带信号进行校准。并将校准后的信号作为新的数字基带信号发送给所述模拟发射模块22和所述DPD反馈更新模块24。
可选地，第i个频率控制字可以用于指示对处理后的模拟信号所占频谱划分为N等分，且第i个频率控制字为第i个子频谱对应的频率控制字。基于此，模拟反馈模块23接收到该第i个频率控制字，则可以根据处理后的模拟信号所占频谱的带宽确定第i个子频谱的相位信息以及第i个子频谱对应的第一中心频点。例如：第1个频率控制字可以用于指示对处理后的模拟信号所占频谱划分为4等分，第1个频率控制字为第1个子频谱对应的频率控制字。假设模拟反馈模块23确定处理后的模拟信号所占频谱的带宽为[-50MHz，50MHz]。模拟反馈模块23根据第1个频率控制字将[-50MHz，50MHz]划分为4等份，分别为[-50MHz，-25MHz]，[-25MHz，0MHz]，[0MHz，25MHz]和[25MHz，50MHz]。由于第1个频率控制字为第1个子频谱对应的频率控制字，因此模拟反馈模块23可以确定第1个子频谱的相位信息为[-50MHz，-25MHz]，确定第1个子频谱的第一中心频点为-37.5MHz。模拟反馈模块23还可以采用同样的方法计算第2-4个子频谱分别对应的相位信息以及第2-4个子频谱分别对应的第一中心频点。
可选地，第i个频率控制字可以用于指示对处理后的模拟信号所占频谱划分为N个子频谱，其中N个子频谱的带宽可以构成等差数列或者等比数列等。且第i个频率控制字为第i个子频谱对应的频率控制字。
需要说明的是，无论上述的N个子频谱带宽相同或者不同，上述处理后的模拟信号所占频谱都是由所述N个子频谱构成，且相邻子频谱之间无交集。
可选地，发射机可以将每个子频谱的相位信息存储在寄存器中。
上述过程中，当模拟反馈模块23经过N次扫频后，将得到N个第一数字信号。其中第一数字信号和处理后的模拟信号所占频谱所包括的子频谱一一对应。
由于处理后的模拟信号的频谱与数字基带信号的频谱相同。因此DPD反馈更新模块24根据第i个频率控制字确定的第二中心频点与第一中心频点也相同，即可以使得第一中心频点和第二中心频点对齐。并且DPD反馈更新模块24根据所述第i个频率控制字确定的所述处理后的模拟信号对应的第i个子频谱的相位和所述数字基带信号对应的第i个子频谱的相位也相同。即根据所述第i个频率控制字实现所述处理后的模拟信号对应的第i个子频谱的相位和所述数字基带信号对应的第i个子频谱的相位的对齐。
DPD反馈更新模块24根据第1-N个频率控制字分别确定N个对应的第二中心频点。基于此，DPD反馈更新模块24将根据N个第二中心频点对数字基带信号进行处理，得到N个对应的第二数字信号。最后计算所述第一数字信号和对应的第二数字信号的误差值。并根据N次扫频对应的所述误差值确定DPD系数，将所述DPD系数发送给所述DPD器21。
最后，DPD器21还用于根据所述DPD系数对所述数字基带信号进行校准。并将校准后的信号作为新的数字基带信号发送给所述模拟发射模块22和所述DPD反馈更新模块24。模拟发射模块22和DPD反馈更新模块24对新的数字基带信号的处理方法与上述对数字基带信号的处理方法完全相同，模拟反馈模块23对处理后的模拟信号的处理方法也与上述处理后的模拟信号的处理方法完全相同，在此不再赘述。
本申请提供一种发射机，其中模拟反馈模块可以对处理后的模拟信号进行N次扫 频，并得到N个对应的第一数字信号。DPD反馈更新模块可以对数字基带信号进行相应处理得到第二数字信号。最后DPD反馈更新模块可以计算第一数字信号和对应的第二数字信号的误差值。并根据N次扫频对应的误差值确定DPD系数，以使DPD器根据该DPD系数对数字基带信号进行校准。由于模拟反馈模块无需对处理后的模拟信号所占整个带宽进行采样，而是进行分段扫频，之后DPD反馈更新模块根据该分段扫频的结果进行相应的拼接，以获得DPD系数。从而可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
实施例二
基于实施例一的基础，下面将进一步对上述模拟发射模块22进行细化。具体地，图3为本申请实施例二提供的发射机的示意图。如图3所示，该模拟发射模块22包括：数模转换器(Digital to Analog Converter，DAC)221、第一混频器222、放大器223和第一本振振荡器224。
所述数模转换器221，用于将所述数字基带信号转换为模拟基带信号，并将所述模拟基带信号发送给所述第一混频器222。
所述第一本振振荡器224，用于生成本振信号，并将所述本振信号发送给所述第一混频器222。
所述第一混频器222，用于根据所述本振信号对所述模拟基带信号进行调频，并将调频后的模拟信号发送给所述放大器223。
所述放大器223，用于对所述调频后的模拟信号进行放大，得到所述处理后的模拟信号，并将所述处理后的模拟信号发送给与所述模拟发射模块22连接的天线和所述模拟反馈模块23。
可选地，第一混频器222具体用于根据所述本振信号对所述模拟基带信号由低频调节至高频。
可选地，所述放大器223之后还可以连接一个混频器，该混频器也可以与一个本振振荡器连接，以通过该本振振荡器生成的本振信号对放大器223输出的放大信号进行调频。并且该混频器之后还可以连接一个放大器，该放大器用于对该混频器调频后的信号进行放大。本申请对发射机包括的放大器的个数和本振振荡器的个数不做限制。
本申请提供一种发射机，其中提供了模拟发射模块的具体结构。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
实施例三
基于实施例一或者实施例二的基础，下面将进一步对上述模拟反馈模块23进行细化。以结合实施例二为例：具体地，图4为本申请实施例三提供的发射机的示意图。如图4所示，所述模拟反馈模块23包括：第二本振振荡器231、第二混频器232、第一滤波器233和模数转换器ADC234。
所述第二本振振荡器231，用于接收所述DPD反馈更新模块24发送的所述第i个频率控制字；并根据所述第i个频率控制字确定所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息，将所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息发送给第二混频器232。
所述第二混频器232，用于接收所述处理后的模拟信号，并根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的模拟信号，并将所述对应的模拟信号发送给所述第一滤波器233。
所述第一滤波器233，用于对所述对应的模拟信号进行滤波处理，将滤波处理后的模拟信号发送给所述模数转换器234。
所述模数转换器234，用于将所述滤波处理后的模拟信号转换为所述第一数字信号，将所述第一数字信号发送给所述DPD反馈更新模块24。
可选地，第i个频率控制字可以用于指示对处理后的模拟信号所占频谱划分为N等分，且第i个频率控制字为第i个子频谱对应的频率控制字。第二本振振荡器231接收到该第i个频率控制字，则可以根据处理后的模拟信号所占频谱的带宽确定第i个子频谱的相位信息以及第i个子频谱对应的第一中心频点。
可选地，第i个频率控制字可以用于指示对处理后的模拟信号所占频谱划分为N个子频谱，其中N个子频谱的带宽可以构成等差数列或者等比数列等。且第i个频率控制字为第i个子频谱对应的频率控制字。
其中第二本振振荡器231根据第i个频率控制字确定第一中心频点的方法可以采用实施例一所述的具体方法步骤。在此不再赘述。且第二本振振荡器231与第一本振振荡器基于同一参考信息。
可选地，模拟反馈模块23还包括：寄存器235，其中该寄存器235用于存储第1-N个子频谱的相位信息。
可选地，所述第二混频器232具体用于：根据所述处理后的模拟信号对应的第i个子频谱的相位信息确定所述第i个子频谱。根据所述第一中心频点对所述第i个子频谱进行调频。
可选地，第一滤波器233，可以采用现有技术中的低通滤波方法对所述对应的模拟信号进行滤波处理。
本申请提供一种发射机，其中提供了模拟反馈模块的具体结构。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
实施例四
基于实施例一、实施例二或者实施例三的基础，下面将进一步对上述DPD反馈更新模块24进行细化。以结合实施例三为例：具体地，图5为本申请实施例四提供的发射机的示意图。所述DPD反馈更新模块24包括：变换单元241、处理器242和加法器243。
所述处理器242，用于根据所述第i个频率控制字生成第二中心频点，并将所述第二中心频点发送给所述变换单元241。
所述变换单元241，用于接收所述数字基带信号，并根据所述第二中心频点对所述数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到所述第二数字信号；并将所述第二数字信号发送给所述加法器243。
所述加法器243，用于计算所述第一数字信号和对应的第二数字信号的误差值； 并将N次扫频对应的所述误差值发送给所述处理器242。
所述处理器242，还用于根据N次扫频对应的所述误差值确定所述DPD系数，并将所述DPD系数发送给所述DPD器241。
具体的，所述变换单元241具体用于：
通过公式
Figure PCTCN2017075278-appb-000009
计算所述第二数字信号；
x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；x(k)表示在第k次计算所述DPD系数过程中的所述数字基带信号；lpf表示数字低通滤波函数，该数字低通滤波函数可以是现有技术公开的任何数字低通滤波函数，本申请对此不做限制。fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点；k为DPD系数的计算次数。K为大于等于1的正整数。
本申请提供一种发射机，其中提供了DPD反馈更新模块的具体结构和功能。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
实施例五
基于实施例四的基础，下面将进一步对上述变换单元241进行细化。具体地，图6为本申请实施例五提供的发射机的示意图。变换单元241包括：第三混频器2411、第二滤波器2412和第四混频器2413。
所述第三混频器2411，用于接收所述数字基带信号，并根据所述第二中心频点对所述数字基带信号进行傅里叶变换，得到傅里叶变换后的信号。
所述第二滤波器2412，用于对所述傅里叶变换后的信号进行滤波处理。
所述第四混频器2413，用于对滤波处理后的信号再次进行傅里叶变换，得到所述第二数字信号；并将所述第二数字信号发送给所述加法器243。
其中第二滤波器2412可以采用上述的数字低通滤波函数进行滤波处理。
基于实施例四或者实施例五的基础，进一步地，处理器242具体用于：
通过公式
Figure PCTCN2017075278-appb-000010
计算总误差值；
err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第一数字信号；x'i(k)-xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述误差值；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点，k为大于等于1的正整数。
通过公式
Figure PCTCN2017075278-appb-000011
计算所述第k次的DPD系数。
a(k)表示所述第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
Figure PCTCN2017075278-appb-000012
表示xi(k)的共轭。
其中本申请可以采用现有技术提供的任何自适应算法，本申请对此不做限制。
本申请提供一种发射机，其中提供了变换单元的具体结构以及处理器的具体功 能。基于此，该发射机可以准确的计算功放输出信号的非线性特性，进而解决信号校准不够准确的问题。
实施例六
图7为本申请实施例六提供的一种数字预失真校准方法的流程示意图。如图7所示，该方法包括如下步骤：
步骤S701：发射机将数字基带信号处理为模拟信号，并将处理后的模拟信号输出至发射机的天线端。
步骤S702：发射机根据第i个频率控制字确定第i次扫频的第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息；并根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的第一数字信号。
其中所述第i次扫频为所述模拟反馈模块对所述处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为所述处理后的模拟信号的频谱包括的子频谱的数目。
步骤S703：发射机根据第i个频率控制字确定第二中心频点，以使第一中心频点和所述第二中心频点对齐；根据第二中心频点对数字基带信号进行处理，得到对应的第二数字信号。
步骤S704：发射机计算第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的所述误差值确定DPD系数；根据DPD系数对数字基带信号进行校准，并将校准后的信号作为新的数字基带信号，对新的数字基带信号采用与数字基带信号相同的处理。
本申请提供一种数字预失真校准方法，该方法可由上述发射机执行，其具体的实现过程及有益下效果，与上述实施例类似，在此不再赘述。
实施例七
可选地，图8为本申请实施例七提供的一种数字预失真校准方法的流程示意图。如图8所示，可选地，上述步骤S701具体包括：
步骤S701a：发射机将所述数字基带信号转换为模拟基带信号；
步骤S701b：发射机生成本振信号；
步骤S701c：发射机根据本振信号对模拟基带信号进行调频；对调频后的模拟信号进行放大，得到处理后的模拟信号，并将处理后的模拟信号输出至发射机的天线端。
可选地，上述步骤S702具体包括：
步骤S702a：发射机根据第i个频率控制字确定第i次扫频的第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息；
步骤S702b：发射机根据第一中心频点和处理后的模拟信号对应的第i个子频谱的相位信息对处理后的模拟信号对应的第i个子频谱进行第i次扫频，得到对应的模拟信号。
可选地，步骤S702b具体包括：发射机根据所述处理后的模拟信号对应的第i个子频谱的相位信息确定所述第i个子频谱。发射机根据所述第一中心频点对所述第i个子频谱进行调频，得到对应的模拟信号。
步骤S702c：发射机对对应的模拟信号进行滤波处理；将滤波处理后的模拟信号转换为第一数字信号。
可选地，上述步骤S703具体包括：
步骤S703a：发射机根据第i个频率控制字确定第二中心频点，以使第一中心频点和所述第二中心频点对齐。
步骤S703b：发射机根据所述第二中心频点对数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到第二数字信号。
可选地，步骤S703b具体包括：
发射机通过公式
Figure PCTCN2017075278-appb-000013
计算所述第二数字信号。
x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；x(k)表示在第k次计算所述DPD系数过程中的所述数字基带信号；lpf表示数字低通滤波函数；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点；k为大于等于1的正整数。
可选地，步骤S704中：发射机计算所述第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的所述误差值确定DPD系数，包括：
所述发射机通过公式
Figure PCTCN2017075278-appb-000014
计算总误差值；
err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第一数字信号；x'i(k)-xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述误差值；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点，k为大于等于1的正整数；
发射机通过公式
Figure PCTCN2017075278-appb-000015
计算所述第k次的DPD系数；
a(k)表示所述第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
Figure PCTCN2017075278-appb-000016
表示xi(k)的共轭。
本申请提供一种数字预失真校准方法，该方法可由上述发射机执行，其具体的实现过程及有益下效果，与上述实施例类似，在此不再赘述。

Claims (15)

  1. 一种发射机，其特征在于，包括：数字预失真DPD器、模拟发射模块、模拟反馈模块和DPD反馈更新模块；且所述DPD反馈更新模块与所述DPD器连接；
    所述DPD器，用于向所述模拟发射模块和所述DPD反馈更新模块发送数字基带信号；
    所述模拟发射模块，用于将所述数字基带信号处理为模拟信号，并将处理后的模拟信号发送给与所述模拟发射模块连接的天线端和所述模拟反馈模块；
    所述模拟反馈模块，用于接收所述DPD反馈更新模块发送的第i个频率控制字，并根据所述第i个频率控制字确定第i次扫频的第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息；根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号；并将所述第一数字信号发送给所述DPD反馈更新模块；其中所述第i次扫频为所述模拟反馈模块对所述处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为所述处理后的模拟信号的频谱包括的子频谱的数目；
    所述DPD反馈更新模块，用于根据所述第i个频率控制字确定第二中心频点，以使所述第一中心频点和所述第二中心频点对齐；根据所述第二中心频点对所述数字基带信号进行处理，得到对应的第二数字信号；计算所述第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的所述误差值确定DPD系数，将所述DPD系数发送给所述DPD器；
    所述DPD器，还用于根据所述DPD系数对所述数字基带信号进行校准，并将校准后的信号作为新的数字基带信号发送给所述模拟发射模块和所述DPD反馈更新模块。
  2. 根据权利要求1所述的发射机，其特征在于，所述模拟发射模块包括：数模转换器、第一混频器、放大器和第一本振振荡器；
    所述数模转换器，用于将所述数字基带信号转换为模拟基带信号，并将所述模拟基带信号发送给所述第一混频器；
    所述第一本振振荡器，用于生成本振信号，并将所述本振信号发送给所述第一混频器；
    所述第一混频器，用于根据所述本振信号对所述模拟基带信号进行调频，并将调频后的模拟信号发送给所述放大器；
    所述放大器，用于对所述调频后的模拟信号进行放大，得到所述处理后的模拟信号，并将所述处理后的模拟信号发送给与所述模拟发射模块连接的天线和所述模拟反馈模块。
  3. 根据权利要求1或2所述的发射机，其特征在于，所述模拟反馈模块包括：第二本振振荡器、第二混频器、第一滤波器和模数转换器；
    所述第二本振振荡器，用于接收所述DPD反馈更新模块发送的所述第i个频率控制字；并根据所述第i个频率控制字确定所述第一中心频点和所述处理后的模拟信号 对应的第i个子频谱的相位信息，将所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息发送给第二混频器；
    所述第二混频器，用于接收所述处理后的模拟信号，并根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的模拟信号，并将所述对应的模拟信号发送给所述第一滤波器；
    所述第一滤波器，用于对所述对应的模拟信号进行滤波处理，将滤波处理后的模拟信号发送给所述模数转换器；
    所述模数转换器，用于将所述滤波处理后的模拟信号转换为所述第一数字信号，将所述第一数字信号发送给所述DPD反馈更新模块。
  4. 根据权利要求3所述的发射机，其特征在于，所述第二混频器具体用于：
    根据所述处理后的模拟信号对应的第i个子频谱的相位信息确定所述第i个子频谱；
    根据所述第一中心频点对所述第i个子频谱进行调频。
  5. 根据权利要求1-4任一项所述的发射机，其特征在于，所述DPD反馈更新模块包括：变换单元、处理器和加法器；
    所述处理器，用于根据所述第i个频率控制字生成第二中心频点，并将所述第二中心频点发送给所述变换单元；
    所述变换单元，用于接收所述数字基带信号，并根据所述第二中心频点对所述数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到所述第二数字信号；并将所述第二数字信号发送给所述加法器；
    所述加法器，用于计算所述第一数字信号和对应的第二数字信号的误差值；并将N次扫频对应的所述误差值发送给所述处理器；
    所述处理器，还用于根据N次扫频对应的所述误差值确定所述DPD系数，并将所述DPD系数发送给所述DPD器。
  6. 根据权利要求5所述的发射机，其特征在于，所述变换单元具体用于：
    通过公式
    Figure PCTCN2017075278-appb-100001
    计算所述第二数字信号；
    x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；x(k)表示在第k次计算所述DPD系数过程中的所述数字基带信号；lpf表示数字低通滤波函数；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点；k为大于等于1的正整数。
  7. 根据权利要求5或6所述的发射机，其特征在于，所述变换单元包括：第三混频器、第二滤波器和第四混频器；
    所述第三混频器，用于接收所述数字基带信号，并根据所述第二中心频点对所述数字基带信号进行傅里叶变换，得到傅里叶变换后的信号；
    所述第二滤波器，用于对所述傅里叶变换后的信号进行滤波处理；
    所述第四混频器，用于对滤波处理后的信号再次进行傅里叶变换，得到所述第二 数字信号；并将所述第二数字信号发送给所述加法器。
  8. 根据权利要求5-7任一项所述的发射机，其特征在于，所述处理器具体用于：
    通过公式
    Figure PCTCN2017075278-appb-100002
    计算总误差值；
    err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第一数字信号；x′i(k)-xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述误差值；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点，k为大于等于1的正整数；
    通过公式
    Figure PCTCN2017075278-appb-100003
    计算所述第k次的DPD系数；
    a(k)表示所述第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
    Figure PCTCN2017075278-appb-100004
    表示xi(k)的共轭。
  9. 一种数字预失真校准方法，其特征在于，包括：
    发射机将数字基带信号处理为模拟信号，并将处理后的模拟信号输出至所述发射机的天线端；
    所述发射机根据第i个频率控制字确定第i次扫频的第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息；并根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号；其中所述第i次扫频为所述模拟反馈模块对所述处理后的模拟信号对应的第i个子频谱的扫频；i＝1，2……N，N为所述处理后的模拟信号的频谱包括的子频谱的数目；
    所述发射机根据所述第i个频率控制字确定第二中心频点，以使所述第一中心频点和所述第二中心频点对齐；根据所述第二中心频点对所述数字基带信号进行处理，得到对应的第二数字信号；
    所述发射机计算所述第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的所述误差值确定DPD系数；根据所述DPD系数对所述数字基带信号进行校准，并将校准后的信号作为新的数字基带信号，对所述新的数字基带信号采用与所述数字基带信号相同的处理。
  10. 根据权利要求9所述的方法，其特征在于，所述发射机将数字基带信号处理为模拟信号，包括：
    所述发射机将所述数字基带信号转换为模拟基带信号；
    所述发射机生成本振信号；
    所述发射机根据所述本振信号对所述模拟基带信号进行调频；对所述调频后的模拟信号进行放大，得到所述处理后的模拟信号。
  11. 根据权利要求9或10所述的方法，其特征在于，所述根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的第一数字信号，包括：
    所述发射机根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，得到对应的模拟信号；
    所述发射机对所述对应的模拟信号进行滤波处理；将所述滤波处理后的模拟信号转换为所述第一数字信号。
  12. 根据权利要求11所述方法，其特征在于，所述发射机根据所述第一中心频点和所述处理后的模拟信号对应的第i个子频谱的相位信息对所述处理后的模拟信号对应的第i个子频谱进行所述第i次扫频，包括：
    所述发射机根据所述处理后的模拟信号对应的第i个子频谱的相位信息确定所述第i个子频谱；
    所述发射机根据所述第一中心频点对所述第i个子频谱进行调频。
  13. 根据权利要求9-12任一项所述的方法，其特征在于，所述根据所述第二中心频点对所述数字基带信号进行处理，得到对应的第二数字信号，包括；
    所述发射机根据所述第二中心频点对所述数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到所述第二数字信号。
  14. 根据权利要求13所述的方法，其特征在于，所述发射机根据所述第二中心频点对所述数字基带信号进行傅里叶变换，对傅里叶变换后的信号进行滤波处理，对滤波处理后的信号再次进行傅里叶变换，得到所述第二数字信号，包括：
    所述发射机通过公式
    Figure PCTCN2017075278-appb-100005
    计算所述第二数字信号；
    x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；x(k)表示在第k次计算所述DPD系数过程中的所述数字基带信号；lpf表示数字低通滤波函数；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点；k为大于等于1的正整数。
  15. 根据权利要求9-14任一项所述的方法，其特征在于，所述发射机计算所述第一数字信号和对应的第二数字信号的误差值；并根据N次扫频对应的所述误差值确定DPD系数，包括：
    所述发射机通过公式
    Figure PCTCN2017075278-appb-100006
    计算总误差值；
    err(k)表示在第k次计算所述DPD系数过程中的总误差值；x'i(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第二数字信号；xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述第一数字信号；x′i(k)-xi(k)表示在第k次计算所述DPD系数过程中，所述第i次扫频对应的所述误差值；fi(k)表示在第k次计算所述DPD系数过程中的所述第二中心频点，k为大于等于1的正整数；
    所述发射机通过公式
    Figure PCTCN2017075278-appb-100007
    计算所述第k次的DPD系数；
    a(k)表示所述第k次的DPD系数；a(k-1)表示第k-1次的DPD系数；a(0)＝0；μ表示自适应算法更新步进；
    Figure PCTCN2017075278-appb-100008
    表示xi(k)的共轭。
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