WO2004091094A1 - 歪補償装置 - Google Patents
歪補償装置 Download PDFInfo
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- WO2004091094A1 WO2004091094A1 PCT/JP2004/003966 JP2004003966W WO2004091094A1 WO 2004091094 A1 WO2004091094 A1 WO 2004091094A1 JP 2004003966 W JP2004003966 W JP 2004003966W WO 2004091094 A1 WO2004091094 A1 WO 2004091094A1
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- distortion
- signal
- amplifier
- amplified
- frequency
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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
- H03F1/3282—Acting on the phase and the amplitude of the input signal
-
- 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
Definitions
- the present invention relates to a distortion compensating device for compensating for distortion generated in an amplifier for amplifying a signal, and more particularly to a distortion compensating device including first distortion generating means and second distortion generating means for improving the efficiency of distortion compensation. It relates to compensation devices.
- a base station device provided in a mobile communication system employing a W-CDMA (Wide-band Code Division Multiple Access) system as a mobile communication system.
- the radio signal must reach a physically distant mobile station device (CDMA mobile station device). Therefore, the signal to be transmitted is greatly amplified by an amplifier (amplifier) and the transmission output is transmitted. It is necessary to do.
- an amplifier is an analog device, its input / output characteristics are a non-linear function. In particular, after the amplification limit called the saturation point, the output power increases even if the power input to the amplifier increases.
- a base station apparatus includes a transmission power amplification unit (adaptive predistortion) having a function of performing distortion compensation using an adaptive predistortion (APD) technique.
- ACP adjacent channel leak power
- a base station apparatus includes a transmission power amplification unit (adaptive predistortion) having a function of performing distortion compensation using an adaptive predistortion (APD) technique.
- APD adaptive predistortion
- Patent Document 1
- the present invention has been made in view of the above-described conventional circumstances, and has as its object to provide a distortion compensating device capable of improving efficiency in compensating for distortion generated in an amplifier for amplifying a signal. Aim.
- the present invention provides a distortion compensator capable of lowering the clock frequency of a digital device, for example, when compensating for distortion generated in an amplifier that amplifies a signal, as compared with the related art.
- a distortion compensation device compensates for distortion generated in an amplifier for amplifying a signal as follows.
- the first distortion generating means generates distortion for reducing the distortion generated in the amplifier for the signal to be amplified by the amplifier. Further, the second distortion generating means reduces the distortion generated in the amplifier by the distortion generated by the first distortion generating means with respect to the signal based on the signal to be amplified by the amplifier. Generates distortion to reduce components other than components. '
- the order of the process of generating distortion by the first distortion generating unit for the signal amplified by the amplifier and the process of generating distortion by the second distortion generating unit for the signal is as follows. There is no limitation, as long as the configuration is practically effective.
- the second distortion generating means may be provided before the first distortion generating means, or the second distortion generating means may be provided after the first distortion generating means. Two distortion generating means may be provided.
- the configuration including the first distortion generating unit and the second distortion generating unit has been described.
- a configuration in which one or more other distortion generating units are provided may be used. .
- the first signal and the second signal are used to generate distortion for the signal to be amplified by the amplifier, and the sum of these distortions is calculated.
- the distortion generated in the amplifier it is possible to increase the efficiency of distortion compensation.
- a distortion () for canceling distortion generated in the amplifier by the distortion generating unit is used. It is necessary to generate distortion having inverse characteristics), but in a configuration using a plurality of distortion generating means as in the present invention, the sum of the distortion generated by each of the distortion generating means is equal to the distortion generated by the amplifier. Distortion for canceling (distortion having inverse characteristics) is sufficient, and the distortion generated by each distortion generating means can be set to various characteristics.
- various signals may be used as signals to be amplified by the amplifier.
- various amplifiers may be used, for example, one amplifier may be used, or a combination of a plurality of amplifiers may be used.
- examples of distortion generated in the signal when the signal is amplified by the amplifier include amplitude distortion and phase distortion.
- the accuracy for compensating the distortion for example, various accuracy may be used as long as it is practically effective.
- the first distortion generating means various constitutions may be used, for example, a means for generating distortion in a fixedly set mode, or a method for generating distortion based on feedback control. What is generated can be used. Further, for example, a mode in which distortion is generated based on a signal to be amplified by the amplifier can be used.
- generating distortion in a fixedly set manner refers to, for example, a non-adaptive one, and generating distortion based on feedback control means, for example, an adaptive one. Represents.
- the second distortion generating means those having various configurations may be used.
- a means that generates distortion based on feedback control may be used.
- the distortion compensating apparatus according to the present invention has the following configuration as one configuration example.
- the first distortion generating means is configured using an analog device.
- the first distortion generating means generates distortion in a fixed manner in the signal to be amplified by the amplifier.
- the second distortion generating means includes a digital device that operates based on a clock signal. Further, in the second distortion generation means, the distortion generation mode control means controls the distortion generation mode based on the signal to be amplified by the amplifier, and the distortion generation execution means controls the distortion generation mode. In the distortion generation mode controlled by the control means, Distortion is generated for a signal to be amplified by the width unit.
- the second distortion is generated.
- the sampling frequency required for the digital device included in the generating means can be reduced, thereby reducing the frequency of the digital signal required for the digital device included in the second distortion generating means. Can be lower.
- the first-order frequency component included in the component obtained by removing the component reduced by the distortion generated by the first distortion generating means from the distortion generated by the amplifier is reduced so that the first-order frequency component is reduced.
- the generation mode of the distortion generated by the distortion generating means is set.
- higher-order frequency components for example, fifth-order distortion, seventh-order distortion, and higher-order frequency components are used.
- the broadband property is reduced, that is, the width of the frequency band is reduced.
- the first distortion generating means is configured using, for example, only an analog device.
- the second distortion generating means may be configured using, for example, both a digital device and an analog device, or may be configured using only a digital device.
- Various devices may be used as digital devices and analog devices. Further, as a distortion generation mode, for example, an amplitude distortion generation mode, a phase distortion generation mode, or a generation mode of both amplitude and phase distortions can be used.
- a distortion generation mode for example, an amplitude distortion generation mode, a phase distortion generation mode, or a generation mode of both amplitude and phase distortions can be used.
- Various means may be used as the distortion generation executing means.
- means for changing the amplitude of the signal means for changing the phase of the signal, or a method for changing the amplitude and the phase of the signal may be used. Means for changing both can be used.
- the distortion compensating apparatus according to the present invention has the following configuration as one configuration example.
- the signal level detection means detects the level of the signal to be amplified by the amplifier, and the signal level distortion generation mode correspondence storage means stores the correspondence between the signal level and the distortion generation mode. Then, the distortion generation control execution means, based on the content stored in the signal level distortion generation mode correspondence storage means, generates the distortion corresponding to the level of the signal detected by the signal level detection means, and Distortion is generated for the signal to be amplified.
- the signal level distortion generation mode correspondence content change means changes the level and distortion of the signal stored by the signal level distortion generation mode correspondence storage section based on the signal amplified by the amplifier. The content of the correspondence with the generation mode is changed.
- the second distortion generating means compensates for the distortion generated in the amplifier based on the correspondence between the signal level and the distortion generation mode, the content of the correspondence is updated based on the signal amplified by the amplifier.
- the accuracy of distortion compensation can be improved by feedback control.
- various levels may be used as the signal level detected by the signal level detecting means.
- an amplitude level, a power level, and an envelope level may be used. Can be.
- an amplifier outputs according to the level of the input signal.
- the level and phase of the input signal can change.
- the signal level distortion occurrence mode correspondence storage means can be configured using, for example, a memory for storing information.
- the distortion compensating apparatus according to the present invention has the following configuration as one configuration example.
- a radio frequency analog signal is input to the distortion compensator as a signal to be amplified by the amplifier.
- the signal level detection means detects the level of the analog signal to be amplified by the amplifier, and the digital control signal output means outputs the signal level and the distortion generation mode.
- a signal level distortion generation mode corresponding to the correspondence is stored, and a digital control signal for realizing a distortion generation mode corresponding to the level of the signal detected by the signal level detection means is output.
- the control signal DZA conversion means converts the digital control signal output from the digital control signal output means into an analog control signal
- the amplitude / phase distortion generation means converts the control signal DZA Based on the analog control signal obtained by the conversion means, one or both of amplitude and phase are generated for the analog signal to be amplified by the amplifier.
- the first distortion generating means generates a distortion with respect to the analog signal which has been distorted by the amplitude / phase distortion generating means constituting the second distortion generating means, and generates the analog signal which has generated the distortion. Is output to the amplifier.
- the first distortion generating means and the amplifier may be directly connected, for example, or may be indirectly connected via another circuit element.
- the distortion generated by the amplitude and phase distortion generating means constituting the second distortion generating means is made to be mainly composed of relatively low-order frequency components.
- the frequency bandwidth of the control signal for the amplitude and phase distortion generating means Can be made relatively narrow, whereby the sampling frequency required for the control signal D / A conversion means can be reduced.
- the low-order frequency component for example, a third-order distortion frequency component is used.
- the broadband characteristic is reduced, that is, the width of the frequency band is reduced.
- radio frequency various frequencies may be used as the radio frequency.
- the amplitude / phase distortion generating means generates distortion based on the analog control signal, for example, generates higher-order distortion by higher-order frequency components included in the analog control signal, and includes the same in the analog control signal.
- the low-order frequency components generate low-order distortion.
- the amplitude-phase distortion generating means may generate, for example, an amplitude distortion, a phase distortion, or may generate both an amplitude distortion and a phase distortion. ,.
- various means may be used as the amplitude and phase distortion generating means.
- an attenuator (variable attenuator) capable of variably controlling the amount of signal attenuation or a signal amplifying amount may be used.
- An amplifier that can be variably controlled (variable amplifier) and a phase shifter that can variably control the amount of phase change (phase shift) of a signal can be used.
- a combination of a variable attenuator and a variable phase shifter can be used.
- the distortion compensating apparatus according to the present invention has the following configuration as another configuration example.
- a digital signal including an I component and a Q component is input to the distortion compensator as a signal to be amplified by the amplifier.
- the signal level detection means detects the level of the digital signal to be amplified by the amplifier
- the digital control signal output means A signal level distortion generation mode correspondence storage unit for storing a correspondence between a signal level and a distortion generation mode for realizing a distortion generation mode corresponding to a signal level detected by the signal level detection unit; Outputs digital control signal.
- the amplitude and phase distortion generating means converts the amplitude and phase distortion with respect to the digital signal to be amplified by the amplifier based on the digital control signal output from the digital control signal output means. And distortion of one or both of the phases.
- the signal DA conversion means converts the digital signal, which has been distorted by the amplitude / phase distortion generation means constituting the second distortion generation means, into an analog signal
- the signal frequency conversion means converts the frequency of the analog signal obtained by the signal DZA conversion means into a radio frequency.
- the first distortion generating means generates a distortion for the analog signal of the radio frequency obtained by the signal frequency converting means, and outputs the analog signal having the distortion generated to the amplifier.
- the first distortion generating means and the amplifier may be directly connected, for example, or may be indirectly connected via another circuit element.
- the frequency bandwidth of the signal to the DZA conversion means can be relatively narrowed, and thereby the sampling frequency and clock frequency required for the signal D / A conversion means can be reduced.
- the low-order frequency component for example, a third-order distortion frequency component is used.
- the broadband characteristic is reduced, that is, the width of the frequency band is reduced.
- a band (BB: Base Band) signal is used as the digital signal composed of the I component and the Q component.
- the amplitude / phase distortion generating means may generate, for example, an amplitude distortion, a phase distortion, or may generate both the amplitude distortion and the phase distortion. .
- amplitude / phase distortion generating means various means may be used as the amplitude / phase distortion generating means.
- a vector calculator that applies amplitude distortion or phase distortion to a digital signal composed of an I component and a Q component can be used.
- the amplified signal part obtaining means obtains a part of the signal amplified by the amplifier, and the distortion component extracting means is obtained by the amplified signal part obtaining means.
- the distortion component contained in the signal is extracted, and the signal level distortion generation mode correspondence content changing means is stored by the signal level distortion generation mode correspondence storage means so that the distortion component extracted by the distortion component extraction means is reduced. Change the content of the correspondence between the signal level and the distortion generation mode.
- the signal frequency lowering unit lowers the frequency of the signal acquired by the amplified signal partial acquiring unit
- the distortion component extracting unit reduces the distortion included in the signal whose frequency is reduced by the signal frequency lowering unit.
- the A / D conversion means converts the distortion component extracted by the distortion component extraction means from an analog signal to a digital signal
- the signal level distortion generation mode correspondence content changing means outputs the distortion component A / D Based on the digital signal of the distortion component obtained by the D conversion means, the content of the correspondence between the signal level stored by the signal level distortion generation mode correspondence storage unit and the generation mode of the distortion is changed.
- various means may be used as the amplified signal partial acquisition means, for example, a coupler may be used.
- the distortion component extracting means may be used as the distortion component extracting means.
- a filter that extracts a signal component having a frequency corresponding to the distortion component generated by the amplifier may be used.
- the signal level distortion generation mode correspondence content changing means as an example of a mode in which the extracted distortion component is controlled to be small, a mode in which the extracted distortion component is controlled to be minimized is used. preferable.
- the signal frequency lowering means may use, for example, a mode in which the frequency of a signal is reduced from a radio frequency to an intermediate frequency (IF) or a baseband frequency.
- IF intermediate frequency
- the signal to be amplified by the amplifier is a quadrature-modulated signal.
- the amplified signal part obtaining means obtains a part of the signal amplified by the amplifier
- the signal demodulation means performs quadrature demodulation of the signal obtained by the amplified signal part obtaining means
- the level of the signal stored in the signal level distortion occurrence mode correspondence storage means is adjusted so that the content changing means reduces the difference between the signal to be amplified by the amplifier and the signal obtained by the quadrature demodulation by the signal demodulation means. Change the content of the correspondence between and distortion generation mode.
- the signal frequency lowering means lowers the frequency of the signal acquired by the amplified signal part acquiring means, and the signal filtering means filters the signal whose frequency has been decreased by the signal frequency lowering means, Filtering signal
- the AD conversion means converts the signal filtered by the signal filtering means from an analog signal to a digital signal. Then, the signal demodulation unit performs quadrature demodulation based on the digital signal of the distortion component obtained by the filtering signal A / D conversion unit.
- various methods may be used as the modulation method applied to the signal to be amplified by the amplifier, for example, QPSK (Quadrature Phase Shift Keying) and QAM (Quadrature Amplitude Modulation).
- QPSK Quadrature Phase Shift Keying
- QAM Quadrature Amplitude Modulation
- the data to be transmitted is converted into an I signal (I component signal) and a Q signal (Q component signal) by modulation such as QPSK and QAM, and this is modulated by orthogonal modulation.
- the signal is converted to an intermediate frequency (IF) signal, which is up-converted and converted to a radio frequency (RF) signal.
- IF intermediate frequency
- RF radio frequency
- a received radio frequency (RF) signal is down-converted and converted into an intermediate frequency (IF) signal, which is converted into an I signal and a Q signal by orthogonal demodulation and demodulated. And convert it to data.
- the signal to be amplified by the amplifier and the signal obtained by quadrature demodulation by the signal demodulation means are used. Detecting the difference is performed.
- a coupler may be used.
- the signal level distortion generation mode correspondence content changing unit is an example of a mode in which the difference between the signal to be amplified by the amplifier and the signal obtained by quadrature demodulation by the signal demodulation unit is controlled to be small.
- a mode in which control is performed so that the difference is minimized can be used.
- the signal frequency lowering means for example, a mode in which the frequency of a signal is reduced from a radio frequency to an intermediate frequency can be used.
- signal filtering means may be used.
- a filter that extracts a signal component having a frequency corresponding to a component of a signal to be amplified by an amplifier can be used.
- the distortion compensating device is provided in, for example, a wireless or wired communication device, a transmitter, a transceiver, and the like, and a signal to be transmitted is used as a signal to be amplified by an amplifier.
- the distortion compensating apparatus employs a wireless communication system employing a CDMA method or the like.
- FIG. 1 is a diagram showing a configuration example of an amplifier according to a first embodiment of the present invention.
- FIG. 2 is a diagram illustrating an example of a characteristic of a distortion compensation table.
- FIG. 3 is a diagram showing an example of a spectrum of a control signal output from the DZA converter.
- FIG. 4 is a diagram showing an example of a spectrum of a control signal output from the D / A converter.
- FIG. 5 is a diagram showing an example of a comparison of the spectrum of the control signal output from the DZA converter.
- FIG. 6 is a diagram showing a configuration example of an amplifying device according to a second embodiment of the present invention.
- FIG. 7 is a diagram illustrating an example of comparison of the spectrum of a signal output from the D / A converter.
- FIG. 8 is a diagram showing a configuration example of an amplifier according to a third embodiment of the present invention.
- FIG. 9 is a diagram illustrating an example of characteristics of an ideal distortion compensation table.
- FIG. 10 is a diagram showing an example of a characteristic of a distortion compensation table when a fixed predistortion and an adaptive predistortion are used.
- FIG. 11 is a diagram showing an example of a spectrum of a control signal output from the DZA converter.
- FIG. 11 (a) shows a case of adaptive PD only
- FIG. 11 (b) shows a case of fixed PD + adaptive PD. Show.
- FIG. 12 is a diagram showing an example of a spectrum of a signal output from the D / A converter. Yes, (a) shows the case of adaptive PD only, (b) shows the case of fixed PD + adaptive PD.
- FIG. 13 is a diagram showing a configuration example of a transmission power amplifier with an adaptive predistorter.
- FIG. 14 is a diagram showing a configuration example of a transmission power amplifier with an adaptive predistorter.
- FIG. 15 is a diagram illustrating an example of characteristics of an output from the DZA converter.
- FIG. 16 is a diagram showing an example of a spectrum of a control signal output from the D / A converter, where (a) shows a case where the sampling frequency is fsl (fsl ⁇ fs2), and (b) shows a sampler. It shows the case where the switching frequency fs2 (fsl ⁇ fs2).
- FIG. 17 is a diagram showing an example of the spectrum of a signal output from the DZA converter, where (a) shows the case of the sampling frequency fsl (fsl ⁇ fs2), and (b) shows the case of the sampling frequency. Shows the case of f s2 (fsl ⁇ fs2).
- BEST MODE FOR CARRYING OUT THE INVENTION An embodiment according to the present invention will be described with reference to the drawings.
- FIG. 13 shows a configuration example of a transmission power amplifier with an adaptive predistorter that performs analog predistortion.
- FIG. 5 shows an operation example of the transmission power amplifier with an adaptive predistorter shown in FIG. That is, an analog signal of a radio frequency (R F: Radio Frequency) is input to the power detection unit 51 and the delay unit 58.
- R F Radio Frequency
- the power detector 51 detects the power of the input signal by performing, for example, envelope detection.
- a voltage representing the detection result is converted from an analog signal to a digital signal by an A / D (Analog to Digital) converter 52, and is configured by, for example, a memory 53. It is associated as a reference argument of the distortion compensation table.
- the distortion compensation table of the memory 53 stores a table for performing distortion compensation by a pre-distortion method.
- the table describes information on the inverse characteristic of the nonlinear characteristic in the amplitude and phase planes to be compensated.
- AM Amplitude Modulation
- AM-AM conversion using the power of the input signal as an index
- AM-PM Phase Modulation
- one of the digital control signals is D / A (Digital to Digital) according to the input from the AZD converter 52 (in this example, the power of the input signal) by referring to the distortion compensation table. Analog) is output to the converter 54, and the other digital control signal is output to the D / A converter 56.
- D / A Digital to Digital
- One digital control signal is converted to an analog signal by a D / A converter 54, band-limited to a required frequency component by an LPF 55, and a voltage variable attenuator 5 for compensating AM-AM conversion. 9 to control the voltage variable attenuator 59.
- the other digital control signal is converted to an analog signal by the D / A converter 56, and the band is limited to the required frequency component by the LPF 57, and the voltage variable phase shifter compensates for AM-PM conversion. 60 to control the voltage variable phase shifter 60.
- the input signal is given a delay time by the delay unit 58 and is input to the variable voltage attenuator 59.
- the delay time is, for example, the time at which the input signal is input to the voltage variable attenuator 59 and the output (control signal) from the DZA converter 54 based on the power of the input signal. 5
- the time to reach 9 is set to match.
- the signal pre-distorted by the pre-distortion method in the variable voltage attenuator 59 and the variable voltage phase shifter 60 corresponding to the predistortion is amplified by the amplifying unit 61.
- the output signal (amplified signal) from the amplifying unit 61 becomes a signal without distortion when ideal distortion compensation is performed.
- a part of the output signal from the amplifier 61 is extracted by the directional coupler 62.
- a part of the signal is down-converted by the mixer 64 using the transmission signal from the transmitter 63 controlled by the adaptive table control unit 67.
- the frequency band component of the distortion is extracted from the downconverted signal by a band pass filter (BPF) 65, and the extraction result is converted from an analog signal to a digital signal by an AZD converter 66. Then, it is inputted to the adaptive table controller 67.
- BPF band pass filter
- the adaptive table control unit 67 receives the information on the power of distortion from the AZD converter 66. Then, the adaptive table control unit 67 updates the contents of the distortion compensation table stored in the memory 53 and controls the distortion compensation table adaptively so that the power of the distortion is reduced. As a result, the distortion component remaining in the output signal from the amplification section 61 is reduced.
- FIG. 14 shows an example of the configuration of a transmission power amplifier with an adaptive predistorter for performing digital predistortion.
- FIG. 5 shows an operation example of the transmission power amplifier with an adaptive predistorter shown in FIG.
- a digital signal composed of an I-phase component (I component) and a Q-phase component (Q component) is input to the power calculation unit 71, the vector calculation unit 73, and the adaptive table control unit 83.
- the input signal is, for example, a signal that handles multicarriers, and is quadrature-modulated before being input to the transmission power amplifier with an adaptive predistorter.
- the power calculator 71 detects the power of the input signal.
- the detection result is associated as a reference argument of the distortion compensation table configured by the memory 72.
- the distortion compensation table of the memory 72 stores a table for performing distortion compensation by a predistortion method.
- the table describes information on the inverse characteristic of the nonlinear characteristic in the amplitude and phase planes to be compensated, and generally relates to AM_AM conversion or AM_PM conversion using the power of the input signal as an index. Information is described Have been.
- the AM-AM conversion is for amplitude
- the AM-PM conversion is for phase
- the distortion compensation table uses, for example, a rectangular coordinate format (for example, a format such as (x, y) or (1, Q)) in order to perform a vector operation relating to AM-AM conversion or AM-PM conversion. Control information is stored.
- a rectangular coordinate format for example, a format such as (x, y) or (1, Q)
- the digital control signal is sent to the vector operation unit 73 according to the input from the power operation unit 71 (in this example, the power of the input signal) by referring to the distortion compensation table. Is output.
- a vector operation unit 73 corresponding to a predistorter controls the amplitude and phase of an input signal according to a digital control signal that is a reference result of a distortion compensation table.
- the input signal pre-distorted by the vector operation unit 73 in this manner is converted from a digital signal to an analog signal by the D / A converter 74, and the radio frequency (RF) is converted by the up-converter 75.
- the frequency-converted signal is converted into a signal of the same frequency, and unnecessary signals outside the required frequency band are removed from the signal after the frequency conversion by a band-pass filter (BPF) 76.
- BPF band-pass filter
- the signal power S pre-distorted by the predistortion method is amplified by the amplification unit 77 in the beta calculation unit 73 as described above.
- the output signal (amplified signal) from the amplification unit 77 becomes a signal without distortion when ideal distortion compensation is performed.
- a part of the output signal from the amplifier 77 is obtained by the directional coupler 78.
- the part of the signal is frequency-converted to a lower frequency by the down-converter 79, and unnecessary signals outside the necessary frequency band are removed from the frequency-converted signal by a low-pass filter (LPF) 80. Is done.
- the signal from which unnecessary signals outside the band have been removed by the LPF 80 is converted to the AZD converter 8 1 Is converted from an analog signal to a digital signal.
- the quadrature demodulation unit 82 performs quadrature demodulation based on the digital signal, and the result of the quadrature demodulation is input to the adaptive table control unit 83 as a feedback signal.
- the adaptive table control unit 83 receives the input signal and the feed pack signal from the quadrature demodulation unit 82 and stores it in the memory 72 so that the error between the input signal and the feedback signal is reduced.
- the contents of the distortion compensation table thus updated are updated, and the distortion compensation table is adaptively controlled. As a result, the distortion component remaining in the output signal from the amplifier 77 is reduced.
- FIG. 15 shows an example of the characteristics of the output from the DZA converter.
- the spectrum of the signal output from the D / A converter when the signal whose frequency bandwidth is W [Hz] is input to the DZA converter and the sampling frequency is fs [Hz] is shown.
- An example of a torque is shown.
- the horizontal axis of the graph shown in the figure represents the frequency [H z], and the vertical axis represents the intensity of the spectrum.
- n represents an arbitrary integer of 1 or more.
- sampling theorem is satisfied by the condition that “sampling frequency f s ⁇ frequency bandwidth W of input signal”.
- the input signal after predistortion is the same as the frequency band of the input signal before predistortion.
- the required sump is wider than The ring frequency becomes very high, and the required click frequency becomes very high.
- the frequency band of the input signal after predistortion is at least three times the frequency band of the input signal before predistortion, so the required sampling frequency is also tripled. That is all.
- the frequency band of the input signal after predistortion is at least five times the frequency band of the input signal before predistortion. More than double.
- FIG. 16 (a) shows an example of a spectrum of a control signal output from the D / A converters 54 and 56 when a relatively low sampling frequency fsi [Hz] is used. .
- FIG. 16 (b) shows an example of a control signal pattern output from the D / A converters 54 and 56 when a relatively high sampling frequency fs 2 [Hz] is used. It is. Where f s i and f s 2.
- the horizontal axis of the graphs shown in FIGS. 7A and 7B indicates frequency [Hz], and the vertical axis indicates the intensity of the spectrum.
- FIGS. 3A and 3B the spectrum of the control signal (shown by the solid line) having a center frequency of 0 [Hz] and the center frequency of fs 1 [Hz] and fs 2 [Hz] are shown.
- the spectrum of the image signal (shown by the dotted line) is shown.
- the sampling frequency fs1 is smaller than the sufficient value. If it is low, the control signals output from the D / A converters 54 and 56 and the image signal overlap, which is not preferable. For this reason, it is necessary to use a very high sampling frequency fs 2 as shown in FIG.
- Fig. 17 (a) shows an example of the spectrum of the input signal after predistortion output from the DZA converter 74 when a relatively low sampling frequency fsi [Hz] is used. is there.
- FIG. 17 (b) shows an example of the spectrum of the input signal after predistortion output from the DZA converter 74 when a relatively high sampling frequency fs 2 [Hz] is used. Is shown. Here, fs1 and fs2.
- the horizontal axis of the graphs shown in FIGS. 7A and 7B indicates the frequency [Hz], and the vertical axis indicates the intensity of the spectrum.
- the sampling frequency fs1 is smaller than the sufficient value. If it is low, the input signal after pre-distortion output from the D / A converter 74 and the image signal overlap, which is not preferable. For this reason, it is necessary to use a very high sampling frequency fs 2 as shown in FIG.
- the clock frequency of the other digital parts also needs to be very high. Higher clock frequencies make devices more expensive, technically more difficult, or impossible to implement.
- FIG. 1 shows a first embodiment according to the present invention.
- This example shows a case where the distortion compensator according to the present invention is applied to an amplifier having a distortion compensation function (a transmission power amplifier with an adaptive pre-distorter) as shown in FIG.
- a distortion compensation function a transmission power amplifier with an adaptive pre-distorter
- the frequency (clock frequency) of the clock signal required for the digital system is reduced, for example, as compared with the conventional system.
- FIG. 1 shows a configuration example of the amplifying device of the present example.
- the amplifying device of this example includes a power detector 1, an AZD converter 2, a memory 3 for storing a distortion compensation table, a D / A converter 4, a low-pass filter (LPF) 5, / A transformer 6, low-pass filter (LPF) 7, delay unit 8, variable voltage attenuator 9, variable voltage phase shifter 10, fixed predistorter 11, amplifier 12 A directional coupler 13, a transmitter 14, a mixer 15, a band-pass filter (BPF) 16, an AZD converter 17, and an adaptive table controller 18 are provided.
- LPF low-pass filter
- LPF low-pass filter
- LPF low-pass filter
- the configuration and operation of the amplifying apparatus of this example are the same as those of the above-described first to third embodiments except that the clock frequency required for the digital system is reduced by using the fixed predistorter 11, for example. This is the same as the configuration and operation of the amplification device shown in the figure.
- the signals input from the preceding processing unit (not shown) to the amplifying device of this example are two signals.
- the first distribution signal is input to the power detection unit 1 and the second distribution signal is input to the delay unit 8.
- the power detection unit 1 detects the power of a radio frequency (RF) signal to be transmitted, which is input from a processing unit (not shown) at the preceding stage, and outputs the detection result to the A / D converter 2 I do.
- RF radio frequency
- the AZD converter 2 converts the detection result of the power input from the power detection unit 1 from an analog signal to a digital signal and outputs the signal to the memory 3.
- the memory 3 outputs a result obtained by referring to the distortion compensation table to the DZA converters 4 and 6 using the digital signal input from the AZD converter 2 as an index based on the contents of the stored distortion compensation table.
- the distortion compensation table stores the value of the digital signal representing the detection result of the power, the control value to the voltage variable attenuator 9 and the control value to the voltage variable phase shifter 10 in association with each other. are doing.
- the memory 3 outputs the control value (digital control signal) to the voltage variable attenuator 9 corresponding to the value of the digital signal input from the AZD converter 2 to the DZA converter 4 with reference to the distortion compensation table.
- the control value (digital control signal) to the voltage variable phase shifter 10 corresponding to the value of the digital signal input from the A / D converter 2 is output to the DZA converter 6.
- the DZA converter 4 converts the digital control signal input from the memory 3 into an analog control signal and outputs the analog control signal to the LPF 5.
- the LPF 5 filters the analog control signal input from the D / A converter 4 and outputs the filtered signal to the control terminal of the voltage variable attenuator 9.
- the D / A converter 6 converts the digital control signal input from the memory 3 into an analog control signal and outputs the analog control signal to the LPF 7.
- the LPF 7 filters the analog control signal input from the D / A converter 6 and outputs the filtered signal to the control terminal of the voltage variable phase shifter 10.
- the delay unit 8 is configured to transmit a radio signal to be transmitted from a preceding processing unit (not shown).
- the signal of the frequency (RF) is delayed so as to match the timing at which the control signal based on the input signal is input to the variable voltage attenuator 9 and the variable voltage phase shifter 10 and output to the variable voltage attenuator 9 I do.
- the delay unit 8 converts the input radio frequency (RF) signal into a control signal based on the input signal by the DZA converter 4 and converts it into an analog signal by the same time. Delay.
- variable voltage attenuator 9 controls the amplitude of the delayed input signal input from the delay unit 8 with the amount of attenuation according to the analog control signal input from the LPF 5, and converts the controlled signal to a voltage. Output to variable phase shifter 10.
- variable voltage attenuator 9 it is also possible to use, for example, a variable voltage amplifier that controls the amplitude of the signal with an amplification amount according to the analog control signal.
- variable voltage phase shifter 10 controls the phase of the signal input from the variable voltage attenuator 9 with the amount of phase change in accordance with the analog control signal input from the LPF 7, and converts the signal after the control. Output to fixed predistorter 1 1
- variable voltage phase shifter 10 is provided at the subsequent stage of the variable voltage attenuator 9 .
- an order reverse to that of the present example may be used as the order of these arrangements.
- the fixed predistorter 11 is configured using, for example, a non-linear element.
- the fixed predistorter 11 generates a distortion for a signal input from the voltage variable phase shifter 10 and amplifies the signal having the distortion to an amplifying unit 1. Output to 2.
- the fixed predistorter 11 generates a distortion in the input signal according to the level of the signal.
- the adaptive predistortion using the variable voltage attenuator 9 and the variable voltage phase shifter 10 and the fixed predistortion using the fixed predistorter 11 (non-adaptive ), Distortion compensation is performed by the pre-distortion method.
- the amplification unit 12 amplifies the signal input from the fixed predistorter 11 and The amplified signal is output to, for example, a subsequent antenna (not shown).
- the signal is distorted in the amplifier 12.
- the signal is distorted by the amplitude distortion generated by the variable voltage attenuator 9 and the phase distortion generated by the variable voltage phase shifter 10. Also, it is reduced by the amplitude distortion and the phase distortion generated by the fixed predistorter 11.
- the directional coupler 13 extracts a part of the amplified signal output from the amplifier 12 and outputs the extracted signal to the mixer 15.
- the oscillator 14 oscillates a signal having a frequency controlled by the adaptive table controller 18 and outputs the signal to the mixer 15.
- the mixer 15 mixes the amplified signal input from the directional coupler 13 and the signal input from the oscillator 14 to convert the frequency of the amplified signal, and the amplified signal after the frequency conversion. Is output to BPF 16.
- the BPF 16 limits the band of the signal input from the mixer 15 and outputs the signal after the band limitation to the A / D converter 17.
- the AZD converter 17 converts the signal input from the BP 16 from an analog signal to a digital signal, and outputs the signal to the adaptive table controller 18.
- the adaptive table controller 18 updates the contents of the distortion compensation table stored in the memory 3 based on the digital signal input from the A / D converter 17 and causes the oscillator 14 to oscillate. Controls the frequency of the signal.
- the distortion component included in the amplified signal is extracted by the BPF 16 and the content of the distortion compensation template is updated by the adaptive table control unit 18 so that the level of the distortion component is reduced. Control is being performed, and the characteristics of the pass band of the BPF 16 and the frequency of the signal oscillated by the transmitter 14 are set or controlled so that such control is appropriately performed.
- the distortion compensation table generally has a table relating to amplitude and a table relating to phase, here, for simplicity of description, description will be made focusing on only the table relating to amplitude.
- the table for the phase is the same as the table for the amplitude.
- Figure 9 shows the characteristics of the ideal distortion compensation table of the adaptive predistorter using the variable voltage attenuator 9 and the variable voltage phase shifter 10 when the fixed predistorter 11 is not provided.
- An example is shown.
- the horizontal axis of the graph shown in the figure represents the power, and the vertical axis represents the voltage of the control signal (control voltage).
- FIG. 10 shows an example of distortion compensation characteristics by the fixed predistorter 11 when the fixed predistorter 11 is provided, and the voltage variable attenuator 9 and the variable voltage phase shifter 10.
- 3 shows an example of characteristics of an ideal distortion compensation table of an adaptive predistorter using the above.
- the horizontal axis of the graph shown in the figure represents power, and the vertical axis represents the voltage (control voltage) of the control signal.
- FIG. 11 (a) shows that when the fixed predistorter 11 is not provided, when the distortion compensation table of the memory 3 has the ideal characteristic shown in FIG.
- FIG. 11 (b) shows that when the fixed predistorter 11 is provided, the distortion compensation table of the memory 3 has an ideal adaptive predistortion (adaptive predistortion) shown in FIG. PD), the DZA converter 4 (or D / A An example of the spectrum of the control signal output from the converter 6) is shown.
- the horizontal axis of the graphs shown in FIGS. 11 (a) and (b) indicates the frequency [Hz], and the vertical axis indicates the spectrum intensity.
- the control signal output from the DZA converter 4 and the image signal may overlap. Even if the sampling frequency fs is low, the provision of the fixed predistorter 11 makes it possible to make the frequency bandwidth of the control signal output from the DZA converter 4 relatively small (narrow). It is possible to prevent the control signal and the image signal from overlapping.
- the sampling frequency fs is lower than in the case without the fixed predistorter, for example, as shown in Fig. 13 above. This makes it possible to lower the digital frequency of the digital system such as the DZA converters 4 and 6.
- the fixed predistorter 11 an analog device is used as the fixed predistorter 11, and therefore has no relation to the sampling rate (sampling frequency).
- the use of such a fixed predistorter 11 attenuates the spectral intensity of the distortion component generated by the adaptive predistorter, thereby reducing the sampling frequency fs and the clock frequency. are doing.
- the distortion compensation table generally has a table relating to the amplitude and a table relating to the phase.
- the following description focuses on only the table relating to the amplitude.
- the table relating to the phase is the same as the table relating to the amplitude.
- FIG. 2 shows a characteristic example (a) of the distortion compensation table according to the comparative example and a characteristic example (b) of the distortion compensation table stored in the memory 3 of the present example.
- the horizontal axis of the graph shown in the figure represents power, and the vertical axis represents the voltage of the control signal (control voltage).
- An example of the spectrum (a) is shown, and an example of the spectrum of the control voltage from the DZA converter 4 (or the same applies to the D / A converter 6) of the present example (b) Is shown.
- the horizontal axis of the graph shown in the figure represents the frequency [MHz], and the vertical axis represents the spectrum intensity (level) [dB].
- the direct current (DC) component has the same spectral intensity, and the other frequency components have the same spectral intensity.
- the spectrum intensity is about 10 [dB] lower than in comparative example (a). This is because the characteristics of the distortion compensation table of this example are closer to a straight line than the characteristics of the distortion compensation table according to the comparative example.
- components required for distortion compensation are included even at 15 [MHz] or higher, but in this example (b), attenuation is sufficient.
- FIG. 4 shows the control from the D / A converter 54 (or the same applies to the zero converter 56) according to the comparative example when the sampling frequency fs is set to about 40 [MHz].
- An example of the voltage spectrum (a) is shown and this example
- An example (b) of the spectrum of the control voltage from the D / A converter 4 (or the same for the DZA converter 6) is shown.
- the horizontal axis of the graph shown in the figure represents frequency [MHz]
- the vertical axis represents spectrum intensity (level) [dB].
- the spectrum intensity is attenuated to about 140 [dB] at about 20 [MHz] where the spectrum of the control signal and the image signal overlaps.
- the signal component required for distortion compensation is as large as about 1.25 [dB], and is affected by the image signal.
- Fig. 5 shows the control voltage of the DZA converter 54 (or the same for the 0 converter 56) when the sampling frequency fs is set to about 40 [M Hz] in the comparative example.
- An example (a) of the spectrum is shown, and from the D / A converter 54 (or the same applies to the D / A converter 56) when the sampling frequency fs is set to about 60 [MHz].
- An example (b) of the spectrum of the control voltage is shown.
- the horizontal axis of the graph shown in the figure represents the frequency [MHz], and the vertical axis represents the spectrum intensity (level) [dB].
- the difference in spectrum due to the difference in sampling frequency can be confirmed.
- f s about 40 [MHz]
- the amplifying apparatus of the present example includes the adaptive predistorter including the variable voltage attenuator 9, the variable voltage phase shifter 10, the DZA converters 4, 6, and the like, and the wideband signal. Another predistorter was provided to reduce the effects.
- an adaptive control distorter such as the adaptive predistorter may be used, but in this example, distortion is compensated in advance.
- (Fixed pre-distorter 11 1) in which distortion information is set.
- the input / output characteristics of the fixed predistorter 11 were adjusted and set so that the distortion generated in the amplifier constituting the amplifying unit 12 was compensated. Then, the fixed predistorter 11 compensates for the distortion generated in the amplifying unit 12 by a predistortion method. As a result, for example, compared to the conventional case, the fixed predistorter 11 stores the distortion compensation table of the memory 3 in the adaptive predistorter. Nonlinearity is reduced, and the spectrum intensity of the output (control signal) from D / A converters 4 and 6 on the high frequency side and low frequency side is reduced.
- the distortion is broadly compensated by the fixed predistorter 11 composed of analog depises, thereby reducing the influence of the distortion component spreading over a wide band and reducing the influence of the wideband signal.
- an adaptive pre-distorter with digital processing will perform accurate distortion compensation in response to environmental changes such as temperature and aging.
- the load is distributed by using the fixed predistorter 11, and the spectrum intensity of the control signal in the adaptive predistorter is reduced, so that the digital sampling rate ( Sampling frequency), and the clock frequency in the adaptive predistorter can be reduced.
- the amplifying apparatus of this example it is not always necessary to use a high-speed device as compared with the conventional example, and the circuit configuration can be easily implemented technically and can be implemented at low cost. Further, in the amplifying device of this example, for example, the convergence speed of the distortion compensation by the adaptive predistorter that updates the contents of the distortion compensation table can be increased as compared with the conventional case. Further, in the amplifying device of this example, for example, the pass frequency band of the LPFs 5 and 7 through which the control signal passes can be narrowed as necessary. This Thus, the amplifying device of this example is very effective.
- the fixed predistorter 11 is provided between the voltage variable phase shifter 10 and the amplifying unit 12, but the position where the fixed predistorter 11 is provided is, for example, an analog port.
- the same effect can be obtained even if an arbitrary position is used as long as the signal is a position where the signal in the preceding stage of the amplification section 12 is processed in the green area, and a pre-distortion method is applied to the input signal to the amplification section 12. Provided that the distortion compensation characteristic is given.
- the fixed predistorter 11 is, for example, a position before the input signal is branched to the power detection unit 1 side and the delay unit 8 side (the position of “a” in FIG. 1), After the input signal is split into the power detection unit 1 and the delay unit 8 and before the delay unit 8 (the position "b” in Fig. 1), the delay unit 8 and the voltage The position between the variable attenuator 9 (the position “c” in FIG. 1) and the position between the variable voltage attenuator 9 and the variable phase shifter 10 (“d” in FIG. 1) It is also possible to prepare for
- variable voltage attenuator 9 and the variable voltage phase shifter 10 have the distortion compensation characteristic of the fixed predistorter 11.
- variable voltage attenuator 9 instead of the variable voltage attenuator 9, it is also possible to use a variable voltage amplifier or the like.
- the adaptive predistorter is not limited to the one in this example, and various types may be used.
- the amplifier of the amplifying unit 12 is subjected to distortion compensation, and a radio frequency analog signal is used as a signal to be amplified by the amplifying unit 12.
- the function of the fixed predistorter 11 constitutes first distortion generating means
- the function of the adaptive predistorter constitutes second distortion generating means.
- the signal level detecting means is constituted by the function of the power detecting section 1
- the signal level distortion generating mode correspondence storage means and the digital control signal output are provided by the function of the memory 3 for storing the distortion compensation table.
- Control signal is constituted by the functions of the D / A converters 4 and 6.
- the D / A converter is constituted by the function of the variable voltage attenuator 9 and the function of the variable voltage phase shifter 10. Phase distortion generating means is configured.
- the function of the directional coupler 13 constitutes a part of the amplified signal
- the function of the oscillator 14 and the function of the mixer 15 constitute the signal frequency lowering means.
- the function of the BPF 16 constitutes the distortion component extraction means
- the function of the AZD converter 17 constitutes the distortion component A / D conversion means
- the function of the adaptive table controller 18 This constitutes a signal level distortion generation mode correspondence content changing unit.
- the adaptive predistorter provided in the amplifying device of the present example includes, for example, a distortion generation mode control unit that controls a distortion generation mode based on an input signal, and a distortion generation execution unit that generates a distortion according to the control.
- a distortion generation control execution unit that generates distortion in a distortion generation mode based on an input signal.
- FIG. 2 shows a second embodiment according to the present invention.
- This example shows a case where the distortion compensator according to the present invention is applied to an amplifier having a distortion compensation function (a transmission power amplifier with an adaptive predistorter) as shown in FIG.
- a distortion compensation function a transmission power amplifier with an adaptive predistorter
- FIG. 6 shows a configuration example of the amplification device of the present example.
- the amplifying device of this example includes a power operation unit 21, a memory 22 for storing a distortion compensation table, a vector operation unit 23, a D / A converter 24, an up converter 25, Bandpass filter (BPF) 26, fixed predistorter 27, amplifier 28, directional coupler 29, downconverter 30, low-pass filter (LPF) 31, and A A / D converter 32, a quadrature demodulation unit 33, and an adaptive table control unit 34 are provided.
- BPF Bandpass filter
- LPF low-pass filter
- the configuration and operation of the amplifying apparatus of the present example are the same as those of the above-described first to fourth embodiments except that the clock frequency required for the digital system is reduced by using a fixed predistorter 27, for example. This is the same as the configuration and operation of the amplification device shown in the figure.
- the signal input from the preceding processing unit (not shown) to the amplifying device of this example is divided into three signals, the first distribution signal is input to the power calculation unit 21, and the second distribution signal is distributed.
- the signal is input to the vector operation unit 23, and the third distribution signal is input to the adaptive table control unit 34.
- the power calculation unit 21 detects the power of the I component and Q component signals to be transmitted input from the preceding processing unit (not shown), and outputs the detection result to the memory 22.
- the input signal is assumed to be modulated by the quadrature modulation method before being input.
- the signal between the vector operation unit 23 and the DZA converter 24 is used. It is also possible to provide a configuration in which a quadrature modulation means is provided in the amplifying device at a position such as a position, and a signal that is not quadrature-modulated is input and the signal is quadrature-modulated by the quadrature modulation means.
- the memory 22 uses the digital signal input from the power calculator 21 as an index based on the contents of the stored distortion compensation table, and uses the result obtained by referring to the distortion compensation table as a vector calculator 2 3 Output to Specifically, the distortion compensation table stores the value of the digital signal representing the detection result of the power and the control value for the beta calculator 23 in association with each other. Then, the memory 22 refers to the distortion compensation table, A control value (digital control signal) corresponding to the value of the digital signal input from the arithmetic unit 21 is output to the vector arithmetic unit 23.
- the vector operation unit 23 calculates the amplitude change amount and the phase change amount according to the digital control signal input from the memory 22, and outputs the I component to be transmitted, It controls the amplitude and phase of the Q component signal and outputs the signal after the control to the D / A converter 24.
- the DZA converter 24 converts the signal input from the beta operation unit 23 from a digital signal to an analog signal, and outputs the signal to the up-converter 25.
- the up-converter 25 converts the frequency of the signal input from the D / A converter 24 into a radio frequency (R F), and outputs the frequency-converted signal to the BP 26.
- the BPF 26 limits the band of the signal input from the up-converter 25, and outputs the signal after the band limitation to the fixed predistorter 27.
- the fixed predistorter 27 is configured by using, for example, a non-linear element, and generates distortion for a signal input from the electric BPF 26, and amplifies the signal generated by the distortion to an amplifier 28. Output to The fixed predistorter 27 generates a distortion in the input signal according to the level of the signal.
- both adaptive predistortion using the beta operation unit 23 and fixed predistortion (non-adaptive predistortion) using the fixed predistorter 27 provide: Performs distortion compensation using the pre-distortion method.
- the amplifying unit 28 amplifies the signal input from the fixed predistorter 27 and outputs the amplified signal to, for example, a subsequent antenna (not shown).
- the signal is distorted in the amplifying unit 28, and in this example, the distortion is the amplitude distortion or the phase distortion generated by the beta operation unit 23, or the fixed predistorter 27. It is reduced by the amplitude distortion and the phase distortion generated by.
- Directional coupler 29 extracts a part of the amplified signal output from amplifying section 28, and outputs the extracted signal to down converter 30.
- Downconverter 30 converts the frequency of the amplified signal input from directional coupler 29 to a lower frequency, and outputs the amplified signal after the frequency conversion to LPF 31.
- LPF 31 limits the band of the signal input from down converter 30 and outputs the signal after the band limitation to A / D converter 32.
- the AZD converter 32 converts the signal input from the LPF 31 from an analog signal to a digital signal and outputs the signal to the quadrature demodulation unit 33.
- the orthogonal demodulation unit 33 orthogonally demodulates the signal input from the A / D converter 32, and outputs a digital signal corresponding to the orthogonal demodulation result to the adaptive table control unit 34.
- the adaptive table control unit 34 includes a signal of an I component and a Q component to be transmitted input from a preceding processing unit (not shown) and a signal of a quadrature demodulation result input from the quadrature demodulation unit 33. (I-component and Q-component signals), the content of the distortion compensation table stored in the memory 22 is updated.
- the signal component corresponding to the input signal is extracted by the LPF 31 and the distortion is adjusted by the adaptive table control unit 34 so that the error between the extracted signal component and the original input signal is reduced.
- Control for updating the contents of the compensation table is performed, and the characteristics of the frequency conversion by the downconverter 30 and the characteristics of the pass band of the LPF 31 are set or adjusted so that such control is appropriately performed. Controlled.
- the distortion compensation table generally comprises a table relating to the amplitude of the tape and a table relating to the phase. It is assumed that the configuration is made using the polar coordinate expression equivalent to R22, and only the table relating to the amplitude will be described.
- the phase table is the same as the amplitude table.
- Figure 9 above shows an example of the characteristics of the ideal distortion compensation table of an adaptive predistorter using the vector operation unit 23 when the fixed predistorter 27 is not provided. It is.
- the horizontal axis of the graph shown in the figure represents the power, and the vertical axis represents the control signal value (amplitude control value) related to the amplitude.
- FIG. 10 shows an example of the characteristic of the distortion compensation by the fixed predistorter 27 when the fixed predistorter 27 is provided, and the adaptive predistorter using the betatle operation unit 23.
- An example of characteristics of an ideal distortion compensation table is shown.
- the horizontal axis of the graph shown in the figure represents power, and the vertical axis represents a control signal value (amplitude control value) related to amplitude.
- Fig. 10 the combination of the characteristics of the fixed predistortion (fixed PD) and the characteristics of the adaptive predistortion (adaptive PD) is shown in Fig. 9 above. Ideally and preferably, it matches the characteristics of an ideal pre-distortion (ideal PD).
- FIG. 12 (a) shows that, when the fixed predistorter 27 is not provided, when the distortion compensation table of the memory 22 has the ideal characteristic shown in FIG. An example of the spectrum of a signal output from the D / A converter 24 is shown.
- FIG. 12 (b) shows the case where the fixed predistorter 27 is provided and the distortion compensation table of the memory 22 is the ideal adaptive predistortion (adaptive adaptive distortion) shown in FIG. 10 shows an example of a spectrum of a signal output from the 0 / converter 24 when it has a characteristic of (PD).
- PD characteristic of
- the horizontal axis of the graphs shown in Fig. 12 (a) and (b) indicates the frequency [Hz].
- the vertical axis indicates the intensity of the spectrum.
- the sampling frequency fs is lower than in the case without the fixed predistorter as shown in Fig. 14, for example. This makes it possible to lower the digital frequency of the digital system such as the DZA converter 24.
- the fixed predistorter 27 has no relation to the sampling rate (sampling frequency).
- the spectrum intensity of the distortion component generated by the adaptive predistorter is attenuated, thereby reducing the sampling frequency fs and the clock frequency. Has been realized.
- the distortion compensation table generally comprises a table relating to the amplitude and a table relating to the phase, but here, for simplicity of description, it is assumed that the distortion compensation table is configured using a polar coordinate equivalent to the memory 22.
- the explanation focuses only on the amplitude related tables.
- the table for the phase is the same as the table for the amplitude.
- FIG. 2 shows a characteristic example (a) of the distortion compensation table according to the comparative example and a characteristic example (b) of the distortion compensation table stored in the memory 22 of the present example.
- the horizontal axis of the graph shown in Fig. 7 shows the power, and the vertical axis shows the value of the control signal related to the amplitude (amplitude; control value).
- FIG. 7 shows an example (a) of a spectrum of a signal from the D / A converter 74 according to the comparative example when processing a two-carrier signal modulated by the CDMA method.
- An example (b) of a spectrum of a signal from the D / A converter 24 of the present example is shown.
- the horizontal axis of the graph shown in the figure indicates frequency [MHz], and the vertical axis indicates spectrum intensity (level) [dB].
- the spectrum intensity of the distortion component generated by the adaptive predistorter is attenuated as compared with the comparative example (a).
- the accuracy of distortion compensation is determined by the characteristics required for the device, such as adjacent channel leakage power (ACP), and the output from the D / A converter 24 is thereby determined.
- the required accuracy eg, power to carrier [dB c] is determined.
- the comparative example (a) requires a frequency band of about 90 [MHz], and the DZA converter 74 A clock frequency of about 180 [MHz], which is twice that of the above, is required, but in this example (b), only a frequency band of about 60 [MHz] is required, and the clock frequency of the DZA converter 24 is You need about 120 [MHz], twice that. It is.
- the intermediate frequency (IF) can be lowered, and the band of the filter (for example, BPF26) can be narrowed.
- the clock frequency of the DZA converter 24 and other digital processing systems can be reduced, and even if the clock frequency is reduced, for example, the same as in the comparative example (a) A degree of distortion compensation accuracy can be obtained.
- the amplifying device of the present example includes the adaptive predistorter including the beta operation unit 23 and the like, and also includes the other predistorter to reduce the influence of the wideband signal.
- an adaptive predistorter for adaptive control like the adaptive predistorter may be used, but in this example, distortion information for compensating distortion is set in advance.
- the fixed one (fixed predistorter 27) was used.
- an analog fixed predistorter 27 that does not perform digital processing is used.
- the input / output characteristics of the fixed predistorter 27 were adjusted and set so that the distortion generated in the amplifier constituting the amplifying unit 28 was compensated.
- the fixed predistorter 27 compensates for the distortion generated in the amplifier 28 by a predistortion method, and as a result, for example, the distortion compensation of the memory 22 in the adaptive predistorter is performed as compared with the conventional case.
- the non-linearity of the table is reduced, and the spectrum intensity of the output from the D / A converter 24 (the signal after adaptive predistortion) on the high frequency side and the low frequency side is reduced.
- the predistorter 27 As described above, in the amplifying apparatus of this example, by performing coarse distortion compensation by the fixed pre-distorter 27 composed of an analog device, the influence of the distortion component spread over a wide band is reduced, and the influence of a wide band signal is reduced. With digital processing The predistorter adapts to environmental changes such as temperature and aging, and performs accurate distortion compensation. In the amplifying apparatus of this example, the load is distributed by using the fixed predistorter 27, and the spectrum intensity of the signal distorted by the adaptive predistorter is reduced. The sampling rate (sampling frequency) can be reduced, and the cut-off frequency in an adaptive predistorter can be reduced.
- the amplifying apparatus of this example it is not always necessary to use a device having a higher speed than that of the conventional device, and the circuit configuration can be easily implemented technically and can be implemented at low cost. Further, in the amplifying device of the present example, for example, the convergence speed of distortion compensation by the adaptive predistorter that updates the contents of the distortion compensation table can be increased as compared with the related art. Further, in the amplifying device of the present example, for example, it is possible to narrow the pass frequency band of the BPF 26 through which the pre-distorted signal passes, if necessary. Thus, the amplifying device of this example is very effective.
- the fixed predistorter 27 is provided between the BPF 26 and the amplifying unit 28, but the position where the fixed predistorter 27 is provided is, for example, an analog region and The same effect can be obtained even if an arbitrary position is used as long as it is a position that processes the signal at the previous stage of the unit 28, and the distortion signal is compensated by the pre-distortion method for the input signal to the amplifier 28. If you are given.
- the fixed predistorter 27 includes a position between the DZA converter 24 and the upconverter 25 (the position “a” in FIG. 6) and an upconverter 25. It is also possible to provide at a position between BPF26 and BPF26 (position “b” in FIG. 6).
- the adaptive predistorter is not limited to the one in this example, and various types may be used.
- the amplifier of the amplifying unit 28 is subject to distortion compensation, and As a signal to be amplified by the width section 28, for example, a digital signal including an I component and a Q component of a baseband (BB) or an intermediate frequency (IF) is used.
- BB baseband
- IF intermediate frequency
- the function of the fixed predistorter 27 constitutes first distortion generating means
- the function of the adaptive predistorter constitutes second distortion generating means.
- signal level detecting means is constituted by the function of the power calculation section 21, and signal level distortion generation mode correspondence storage means and digital control are provided by the function of the memory 22 for storing the distortion compensation table.
- the signal output means is configured, the function of the vector operation section 23 forms the amplitude and phase distortion generation means, and the function of the DZA converter 24 forms the signal D / A conversion means.
- the function of the comparator 25 constitutes a signal frequency conversion means.
- the function of the directional coupler 29 constitutes a part of the amplified signal
- the function of the down converter 30 constitutes the signal frequency lowering means.
- the function of the A / D converter 32 constitutes the filtering signal AZD means
- the function of the quadrature demodulation section 33 constitutes the signal filtering means.
- the function of the adaptive table control section 34 constitutes a signal level distortion occurrence mode correspondence content changing means.
- the adaptive predistorter provided in the amplifying apparatus of the present example includes, for example, a distortion generation mode control unit that controls the generation mode of the distortion based on the input signal, and a distortion generation mode that generates the distortion according to the control. It can be considered as being configured using an execution means, or as being configured using a distortion generation control execution means that generates distortion in a distortion generation mode based on an input signal, for example. is there.
- FIG. 3 shows a third embodiment according to the present invention.
- FIG. 8 shows a configuration example of the amplifying device of this example.
- the amplification device of this example has an adaptive predistortion section (adaptive PD section) 41 for performing adaptive predistortion processing, and a fixed predistortion section (fixed PD section) for performing fixed predistortion processing 4 2 And an amplification unit 43 to be subjected to distortion compensation, and a control unit 44 for controlling the adaptive PD unit 41.
- adaptive PD section adaptive PD section
- fixed PD section fixed predistortion section
- the signal input from the preceding processing unit is divided into two signals, the first distribution signal is input to the adaptive PD unit 41, and the second distribution signal is input to the control unit 44. Is forced.
- the adaptive PD unit 41 generates distortion by an adaptive pre-distortion method for a signal input from a processing unit (not shown) in a preceding stage, and fixes the signal that caused the distortion to a fixed PD unit 4. Output to 2.
- the fixed PD unit 42 generates distortion by a fixed predistortion method for the signal input from the adaptive PD unit 41, and outputs the signal that has caused the distortion to the amplification unit 43.
- the amplifying unit 43 amplifies the signal input from the fixed PD unit 42 and outputs the amplified signal to, for example, a subsequent antenna (not shown).
- the control unit 44 performs an operation by the adaptive PD unit 41 based on one or both of a signal input from a previous processing unit (not shown) and an amplified signal fed back from the amplifier unit 43.
- the adaptive pre-distortion process is controlled.
- the adaptive PD unit 41 and the other PD In the example, by providing the fixed PD unit 42), for example, the clock frequency required for the adaptive PD unit 41 and the like can be reduced, and the efficiency of distortion compensation can be increased.
- the amplifier of the amplifying unit 43 is subjected to distortion compensation
- the first distortion generating means is configured by the function of the fixed PD unit 42
- the function of the adaptive PD unit 41 is configured by the function of the adaptive PD unit 41.
- Second distortion generating means is configured.
- a distortion generation mode control unit that controls the generation mode of the distortion based on the input signal is configured by the function of the control unit 44, and It is also possible to consider that the distortion generation executing means for generating the distortion according to the following is configured by the adaptive PD unit 41.
- the device that gives analog non-linearity to the input to the amplifier has been described as a “fixed predistorter”.
- the device is described as a “linearizer” or another name. Even if it is performed, similar devices are included in the present invention.
- the configurations of the distortion compensating device, the amplifying device, the communication device, and the like according to the present invention are not necessarily limited to those described above, and various configurations may be used.
- the present invention can be provided as, for example, a method or a method for executing the processing according to the present invention, or a program for realizing such a method or method.
- the application field of the present invention is not necessarily limited to the above-mentioned fields, and the present invention can be applied to various fields.
- a processor is stored in a ROM (Read Only Memory) in a hardware resource including a processor and a memory.
- a configuration controlled by executing the control program may be used.
- each functional unit for executing the process may be configured as an independent hardware circuit. Oh good.
- the present invention can be understood as a computer-readable recording medium such as a floppy (registered trademark) CD (Compact Disc) -ROM storing the above-described control program, or the program itself.
- a computer-readable recording medium such as a floppy (registered trademark) CD (Compact Disc) -ROM storing the above-described control program, or the program itself.
- the processing according to the present invention can be performed.
- Industrial Applicability As described above, according to the distortion compensator according to the present invention, for example, the first distortion generating unit composed of an analog device applies an amplifier to a signal to be amplified by the amplifier.
- a second distortion generator including, for example, a digital device is amplified by an amplifier at a stage before and after the first distortion S generator.
- the distortion generated by the amplifier for the target signal cannot be reduced by the distortion generated by the first distortion generator.
- the distortion generated by the amplifier that amplifies the signal is generated by generating distortion to reduce the components.
- By compensating it is possible to improve the efficiency of distortion compensation. Specifically, for example, the sampling frequency required for digital devices is reduced compared to the conventional one, It is possible to realize the current is easy and inexpensive implementation.
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP04722711A EP1612933A4 (en) | 2003-04-07 | 2004-03-23 | DISTORTION COMPENSATION DEVICE |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003102798A JP2004312344A (ja) | 2003-04-07 | 2003-04-07 | 歪補償装置 |
JP2003-102798 | 2003-04-07 |
Publications (1)
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WO2004091094A1 true WO2004091094A1 (ja) | 2004-10-21 |
Family
ID=33156808
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2004/003966 WO2004091094A1 (ja) | 2003-04-07 | 2004-03-23 | 歪補償装置 |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1612933A4 (ja) |
JP (1) | JP2004312344A (ja) |
CN (1) | CN100440727C (ja) |
WO (1) | WO2004091094A1 (ja) |
Families Citing this family (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5501613B2 (ja) * | 2005-06-13 | 2014-05-28 | シーコア ソリューションズ | 4象限リニアライザ |
JP4755651B2 (ja) * | 2005-10-17 | 2011-08-24 | 株式会社日立国際電気 | 非線形歪検出方法及び歪補償増幅装置 |
JP5034319B2 (ja) * | 2006-05-26 | 2012-09-26 | 富士通株式会社 | 歪補償装置及び歪補償方法 |
JP2008277908A (ja) * | 2007-04-25 | 2008-11-13 | Mitsubishi Electric Corp | デジタルプレディストータ |
WO2008146355A1 (ja) * | 2007-05-28 | 2008-12-04 | Panasonic Corporation | 歪補償装置 |
EP2161841B1 (en) | 2008-09-08 | 2012-12-12 | Alcatel Lucent | Predistortion of a radio frequency signal |
JP5121691B2 (ja) * | 2008-12-22 | 2013-01-16 | 株式会社東芝 | 歪補償器、送信機、歪補償方法 |
US8737523B2 (en) * | 2009-06-04 | 2014-05-27 | Xilinx, Inc. | Apparatus and method for predictive over-drive detection |
US8737526B2 (en) * | 2010-06-30 | 2014-05-27 | Qualcomm Incorporated | Predistortion of complex modulated waveform |
US8964821B2 (en) | 2011-10-14 | 2015-02-24 | Qualcomm Incorporated | Shared feedback for adaptive transmitter pre-distortion |
US8837633B2 (en) | 2011-10-21 | 2014-09-16 | Xilinx, Inc. | Systems and methods for digital processing based on active signal channels of a communication system |
JP5782361B2 (ja) * | 2011-11-01 | 2015-09-24 | 株式会社日立国際電気 | ディジタル・プリディストーション方式及び増幅装置 |
US9219554B2 (en) * | 2012-01-20 | 2015-12-22 | Mediatek Inc. | Power detection method and related communication device |
JP6123497B2 (ja) | 2013-06-03 | 2017-05-10 | 住友電気工業株式会社 | 歪補償装置および無線通信装置 |
JP2015099972A (ja) * | 2013-11-18 | 2015-05-28 | 三菱電機株式会社 | 送信機モジュール |
JP6565288B2 (ja) | 2015-04-10 | 2019-08-28 | 富士通株式会社 | 無線装置 |
CN112763769B (zh) * | 2021-04-08 | 2021-07-06 | 深圳市鼎阳科技股份有限公司 | 一种具有超低谐波失真的信号发生器 |
CN113572432A (zh) * | 2021-07-09 | 2021-10-29 | 宁波大学 | 一种可调记忆补偿的模拟预失真器 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001039367A1 (en) * | 1999-11-24 | 2001-05-31 | Telefonaktiebolaget Lm Ericsson (Publ) | Method and apparatus for generating a radio frequency signal |
JP2003078360A (ja) * | 2001-09-05 | 2003-03-14 | Hitachi Kokusai Electric Inc | 歪み補償装置 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP3590571B2 (ja) * | 2000-08-30 | 2004-11-17 | 株式会社日立国際電気 | 歪補償装置 |
-
2003
- 2003-04-07 JP JP2003102798A patent/JP2004312344A/ja active Pending
-
2004
- 2004-03-23 CN CNB200480004343XA patent/CN100440727C/zh not_active Expired - Fee Related
- 2004-03-23 WO PCT/JP2004/003966 patent/WO2004091094A1/ja not_active Application Discontinuation
- 2004-03-23 EP EP04722711A patent/EP1612933A4/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001039367A1 (en) * | 1999-11-24 | 2001-05-31 | Telefonaktiebolaget Lm Ericsson (Publ) | Method and apparatus for generating a radio frequency signal |
JP2003078360A (ja) * | 2001-09-05 | 2003-03-14 | Hitachi Kokusai Electric Inc | 歪み補償装置 |
Non-Patent Citations (1)
Title |
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See also references of EP1612933A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP1612933A4 (en) | 2006-06-21 |
EP1612933A1 (en) | 2006-01-04 |
CN1751432A (zh) | 2006-03-22 |
JP2004312344A (ja) | 2004-11-04 |
CN100440727C (zh) | 2008-12-03 |
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