KR100251781B1 - Apparatus and method for linearizing power amplifier in digital communication system - Google Patents

Abstract

PURPOSE: A device and a method for linearing a power amplifier in a digital communication system is provided to decrease distortion by using an adaptability predistortion algorithm and by performing a data process about digital data of a base band. CONSTITUTION: After a distortion quantity is measured previously according to a level of each channel data, a predistiotion lookup table is stored at a memory(146) in order to remove the measured distortion quantity. At this time, the predistiotion lookup table stores predistiotion data. After this, a distortion is compensated through applying the predistiotion data, which is corresponding to the transmitted channel data, to the transmitted channel data. And, the transmitted channel data is fed back, and the fed back channel data is compared to present channel data. Because an error value generated on the basis of a comparison result is added to pertinent predistortion data and the added value is stored at the predistiotion lookup table corresponding to the present channel data, an error generated at a next distortion compensation is prevented efficiently.

Description

Power amplifier linearization device and method of digital communication system {APPARATUS AND METHOD FOR LINEARIZING POWER AMPLIFIER IN DIGITAL COMMUNICATION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for linearizing power amplifiers in digital communication systems, and more particularly, to an apparatus and method for compensating for distortion of an output spectrum of a transmitter caused by nonlinear characteristics by using a predistortion method.

High-power amplifiers used for transmitting analog signals or digital data in wireless communication systems such as mobile communication require a method of increasing spectral efficiency with high power efficiency. This is to configure the system with less power consumption within the limited frequency band.

In order to satisfy the general requirements of the mobile communication system, a baseband data modulation method such as high-spectrum efficiency such as quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM) is used. In addition, a high efficiency power amplifier such as class C is used to increase the power efficiency. Such a high efficiency power amplifier is generally very strong in nonlinear characteristics. In particular, when a modulated signal having no constant envelope characteristic such as QPSK or QAM passes through a power amplifier having the nonlinear characteristic described above, distortion such as side-lobe reproduction in the output spectrum is generated. Cause

Various methods have been devised to prevent the distortion of the output spectrum caused by the nonlinear characteristics of the power amplifier. The representative methods of these methods are adaptive tracking of the nonlinear characteristics of the power amplifier, and then the baseband data is A method of compensating for an output signal being distorted by a nonlinear characteristic of a power amplifier by pre-distorting and transmitting in a manner opposite to that distorted by a nonlinear characteristic (adaptation predistortion method).

1 shows a conventional linearizer configuration using a predistortion method. Referring to FIG. 1, K-bit data encoded by an encoder (not shown) is applied to the shift register 10 and the modulation select ROM 52. In this case, the shift register 10 has a length of an L-symbol span, and the output has a size of LK bits. In this case, the length L of the shift register 10 is sufficient if there is no system filtering, but the length of the shift register should be longer than 1 symbol if there is a linear distortion caused by the filtering present in the system.

The output of the LK bit of the shift register 10 is applied to a predistortion RAM 12 that outputs predistorted data for transmission to an RF transmitter, and the data that is predistorted and output by the predistortion RAM 12 is transmitted. For this purpose, an analog signal is converted by an I-channel D / A converter 14 and a Q-channel D-A converter 16, respectively. The signals converted to analog by the digital / analog converters 14 and 16 are low-pass filtered by the low pass filters (LPFs) 18 and 20 and then converted into intermediate frequency signals by a quadrature modulator 22. The intermediate frequency output from the modulator 22 is determined by the oscillator (IF OSC) 32 and converted to the final RF transmission frequency in the mixer 24. The final frequency of the mixer 24 is determined by an oscillator (Fc OSC) 28, and the output of the mixer 24 is finally amplified by a power amplifier 26 and then propagated to the air through the antenna.

In addition, a part of the output of the power amplifier 26 is fed back by the coupler (54) and converted to the first intermediate frequency by the mixer 30, wherein the local oscillation signal used is a signal output from the oscillator 28. The intermediate frequency converted signal is converted into baseband data in a demodulator 34. In this case, the local oscillation signal used is a signal output from the oscillator 32. The signal converted to the baseband by the demodulator 34 is compared with the output signals of the digital / analog converters 48 and 50 used as reference signals for generating error signals in the adders 40 and 42. Here, the input signals of the digital / analog converters 48 and 50 become the outputs of the modulation selection ROM 52, which are used as a reference signal for comparison with the signal fed back to update the value of the predistortion RAM 12. The reference and feedback signals added by the analog adders 40 and 42 are added to the digital outputs of the predistortion ram 12 by the digital adders 36 and 46 to update the values of the predistortion ram 12, for which the analog / digital converter 38 And 44 are respectively converted into digital signals. The outputs of the digital adders 36 and 46 are input to the data bus of the predistortion RAM 12, and are written to the address determined by the shift register 10 to finally complete the predistortion process for the baseband data.

The conventional predistortion method having the configuration as shown in FIG. 1 requires the use of the shift register 10 to generate an address, and the modulation selection ROM 52 must be used to obtain a reference signal for generating an error signal. In addition, an error signal is used to update the value of the predistortion RAM 12, and an analog signal is used to generate the necessary error signal, and high precision adders 40 and 42 are required to obtain a precise error signal. However, the configuration of the analog circuit is a difficult problem, and there is a limit in accuracy. In addition, the above configuration has a problem in that the number of digital / analog converters required increases, and there is a limitation in using the DSP when processing high-speed data. In addition, in digital communication systems that accommodate multiple users such as CDMA, the magnitude of the output signal of the digital waveform shaping filter is very severe, and the predistortion algorithm can adapt adaptively to the wide variation of the input signal. This is necessary.

Accordingly, an object of the present invention is to provide a linearization apparatus and method capable of compensating for the distortion of an output spectrum caused by nonlinearity of an active element by adaptively compensating for the nonlinear characteristic of an active element included in a transmitting end of a digital communication system. Is in.

It is another object of the present invention to provide a linearization apparatus and method capable of generating an address directly from a pattern of digital data input in a digital communication system using a lookup table addressing scheme for generating predistorted data.

Another object of the present invention is to feed back by adjusting the delay of the input digital data to generate a reference signal for comparison with the signal fed back in a digital communication system using a lookup table addressing scheme for generating predistorted data. The present invention provides a linearization apparatus and method capable of processing in synchronization with a received signal.

It is still another object of the present invention to provide an apparatus and method for linearizing power amplifier of a transmitter in a CDMA base station system including a plurality of user channels.

According to an aspect of the present invention, a power amplifier linearization device of a digital communication system includes a waveform shaping filter for filtering waveforms by filtering input data into a baseband signal, and an address for generating an address corresponding to the input data. And a predistortion lookup table, the memory for outputting the predistortion data of the address position output from the address generator, and multiplying the output of the waveform shaping filter and the output of the memory to generate predistorted data. A transmitter having a multiplier, a power amplifier, and inputting the predistorted data to output an output signal for compensating for distortion caused by nonlinearity such as the power amplifier; The ratio of generating the comparison data by adjusting the level according to the transmission signal size of the band. A data generator, a reference data generator for delaying the output of the waveform shaping filter with the feedback data and adjusting the level of the delayed data to the magnitude of the feedback signal to generate reference data, and comparing the reference data with the reference data. And a correction data generator for adding the error data to the output of the memory and updating and storing the error data in the predistortion lookup table of the corresponding address position.

1 is a diagram showing the configuration of a power amplifier linearization device used in a conventional mobile communication system.

2 is a diagram illustrating a configuration of a power amplifier linearization apparatus of a base station in a mobile communication system according to an embodiment of the present invention.

2 is a diagram illustrating a configuration of a power amplifier linearization device of a digital communication system according to an embodiment of the present invention.

Referring to FIG. 2, the digital shaping filter 100 pulse-forms, band-limits, and outputs the input baseband I channel data ICD and Q channel data QCD. The address generator 144 inputs input I channel data ICD and Q channel data QCD, and generates addresses corresponding to the respective channel data. The memory 146 includes a predistortion look_up table of I and Q channels that store the predistortion data for measuring the distortion characteristic of the transmitting device generated according to the level of the input data and then compensate for the distortion. . The memory 146 reads the value of the predistortion lookup table stored at the address position of the corresponding channel output from the address generator 144 and outputs the I-channel predistortion data IWP and the Q-channel predistortion data QWP. The multiplier 102 multiplies the I channel data output from the waveform shaping filter 100 and the I channel predistortion data IWP output from the memory 146 to generate predistorted I channel data PICD. The multiplier 104 multiplies the Q channel data output from the waveform shaping filter 100 and the Q channel predistortion data QWP output from the memory 146 to generate predistorted Q channel data PQCD.

A digital to analog converter 106 converts and outputs the predistorted I-channel data PICD into an analog signal. The digital / analog converter 108 converts and outputs the predistorted Q channel data PQCD into an analog signal. The low pass filter 110 low-passes the analog predistorted I channel signal outputted from the digital / analog converter 106 to generate harmonics and spuriouss included in the predistorted I channel signal. Remove it. The low pass filter 112 low-passes the analog predistorted Q channel signal output from the digital-to-analog converter 108 to remove harmonics and spuriouss included in the predistorted Q channel signal. A modulator 114 inputs the outputs of the low pass filters 110 and 112 and modulates the I and Q channel signals that are predistorted and input by the output of the oscillator 120. A high power amplifier 116 amplifies and outputs a transmission output signal output from the modulator 114 to a desired transmission output power.

Coupler 118 generates a feedback signal by combining a part of the final RF signal output from the power amplifier 116. A demodulator demodulator 122 inputs the feedback RF signal, and demodulates the RF signal by the output of the oscillator 120 to generate baseband I-channel signals and Q-channel signals. The low pass filter 124 filters the baseband signal from the demodulated I-channel signal output from the demodulator 122. The low pass filter 126 filters the baseband signal to the demodulated Q channel signal output from the demodulator 122. The analog / digital converter 128 converts the demodulated I-channel signal output from the low pass filter 124 into digital data. The analog / digital converter 130 converts the demodulated Q channel signal output from the low pass filter 126 into digital data. The multiplier 166 multiplies the demodulated I-channel data output from the analog / digital converter 128 by a first constant a. The multiplier 168 multiplies the demodulated Q channel data output from the analog / digital converter 130 by a first constant a. The squarer 162 squares demodulation data of the I channel output from the multiplier 166 and generates the I channel comparison data. The squarer 164 squares demodulation data of the Q channel output from the multiplier 168 to generate comparison data of the Q channel. Such a configuration becomes a comparison data generator.

Delay 148 delays the data of the I-channel output from the waveform shaping filter 100 to compensate for the time the output signal is fed back. The delay unit 150 delays the data of the Q channel output from the waveform shaping filter 100 to compensate for the time when the output signal is fed back. The squarer 174 squares and outputs delayed I-channel data output from the delayer 148. The squarer 176 squares the delayed Q channel data output from the delayer 150 and outputs the squared result. A squaring queue 152 has a memory corresponding to the number of taps of the waveform shaping filter 100, and inputs data of I and Q channels output from the squarers 174 and 176 to the number of taps. Save historical data. The multiplier 170 multiplies the I channel data output from the squarer 174 by the second constant b. The multiplier 172 multiplies the Q channel data output from the squarer 176 by the second constant b and outputs the multiplier. The divider 154 inputs the output of the multiplier 170 and the I-channel data output of the squaring queue 152, and divides and outputs the I-channel data of the squaring queue 152 from the output of the multiplier 170. The divider 156 inputs the output of the multiplier 172 and the Q channel data output of the squaring queue 152, and divides and outputs the Q channel data of the squaring queue 152 from the output of the multiplier 172. The squarer 158 squares the output of the divider 154 to output reference data of the I channel. The squarer 160 squares the output of the divider 156 and outputs reference data of the Q channel. The configuration as described above becomes a reference data generator.

The comparator 132 compares the reference data of the I channel output from the squarer 158 with the comparison data of the feedback I channel output from the squarer 162 and outputs an error signal of the I channel. The comparator 134 compares the reference data of the Q channel output from the squarer 160 with the comparison data of the feedback Q channel output from the squarer 164 and outputs an error signal of the Q channel. The multiplier 136 multiplies the output of the comparator 132 by the error correction coefficient mu i of the I channel. The output of the multiplier 136 becomes error data of the I-channel that was not removed in the process of compensating for the distortion of the currently output I-channel data ICD. The multiplier 138 multiplies the output of the comparator 134 by the error correction coefficient μq of the Q channel. The output of the multiplier 138 becomes error data of the Q channel which was not removed in the process of compensating for the distortion of the currently output Q channel data QCD. The adder 140 adds the output of the multiplier 136 and the predistortion data IWP of the I channel output from the memory 146 and stores the summation data in the I channel predistortion lookup table of the memory 146 corresponding to the address position of the input I channel data ICD. . The adder 142 adds the output of the multiplier 138 and the predistortion data QWP of the Q channel output from the memory 146 and stores the result in the Q channel predistortion lookup table of the memory 146 corresponding to the address position of the input Q channel data QCD. . The configuration is a correction data generator.

The power amplifier linearization apparatus of the digital communication system according to the embodiment of the present invention having the above-described configuration measures the amount of distortion generated according to the level of each channel data transmitted in advance, and stores predistortion data for removing the distortion. The predistortion lookup table is stored in the memory 146. Thereafter, predistortion data corresponding to the channel data input during data transmission are accessed and applied to the input channel data to compensate for the distortion, and the output channel data is fed back and compared with the current data. The error value is added to and stored in the predistortion data of the predistortion table corresponding to the current channel data, thereby effectively preventing an error occurring in the next distortion compensation process.

An embodiment of the present invention as described above will be described in detail with reference to FIG. 2.

The waveform shaping filter 100 pulse-forms the baseband I-channel and Q-channel data and limits the baseband to the baseband, and the oversampled signal is basically input. For systems like IS-95 CDMA, oversampling is quadrupled. Thus, the upsampled and pulse shaped signal by the waveform shaping filter 100 is four times the input signal speed, which is applied to the multipliers 102 and 104 and multiplied by the predistortion data IWP and QWP, respectively. In addition, the channel data ICD and QCD input to the pulse shaping filter 100 are applied to the address generator 144 and generated to the address of the memory 146. The memory 146 includes a predistortion lookup table for the I channel for generating predistortion data corresponding to the I channel data, and a predistortion lookup table for the Q channel for generating predistortion data corresponding to the Q channel data. Therefore, the memory 146 generates predistortion data IWP and QWP corresponding to I-channel data ICD and Q-channel data QCD, respectively, in the address generator 144.

The multiplier 102 multiplies the I channel data output from the waveform shaping filter 100 and the I channel predistortion data output from the memory 146 to generate predistorted I channel data PICD, and the multiplier 104 generates the waveform shaping filter 100. Q-channel data PQCD is output by multiplying the Q-channel predistortion data output from the memory 146 to generate the pre-distorted Q-channel data PQCD. The predistorted data PICD and PQCD are then compensated for by distortion generated by the power amplifier 116 in the process of converting them into RF signals.

In this case, in order to apply the predistortion algorithm to the received data such as the transmitted data, the transmitted data and the received data must match. In addition, the amount of distortion of the transmitter may be changed by the transmission power, the internal temperature, and the elements of the transmitter. Therefore, when the value of the predistortion table stored in the memory 146 is fixed, the distortion compensation efficiency of the transmitter is reduced. In order to solve this problem, when the amount of distortion of the transmitter changes, it is necessary to adaptively track the amount of distortion and update the predistortion data. According to an embodiment of the present invention, after the data is transmitted, the final output signal is predistorted to compensate for distortion, and then compared with the input data, the difference is detected as error data, which is added to the predistortion data to the memory 146 to be transposed. Update the distortion data. Therefore, the predistortion data stored in the memory 146 is updated to a value for compensating for the optimum state in the next state even if the distortion amount change of the transmitting apparatus occurs.

Therefore, for this purpose, the operation for generating reference data of the output data to be fed first will be described. The output of the waveform shaping filter 100 is used to generate reference data for comparison with the feedback data. At this time, in order to apply the predistortion algorithm to the received data such as the transmitted data, the transmitted data and the received data must be synchronized. Therefore, the data of the I channel and the Q channel output from the waveform shaping filter 100 need an appropriate delay time to compensate for the delay occurring in the transmission process. The delayers 148 and 150 input the data output from the waveform shaping filter 100 to compensate for the time delay during the conversion from the transmitter to the RF signal, and can be implemented by an algorithm when using a DSP. Squarers 174 and 176 square the channel data output to the delayers 148 and 150 and input the squared cues 152 and the multipliers 170 and 172, respectively.

The squaring queue 152 has a memory as long as the tap length of the waveform shaping filter 100, and shifts and stores and outputs data output from the squarers 174 and 176. The multipliers 170 and 172 multiply the data of the corresponding channel by the second constant b and output the multipliers. Dividers 154 and 156 divide and output the outputs of multipliers 170 and 172 to the corresponding outputs of the squaring queue 152, respectively. The dividers 154 and 156 respectively output a value obtained by dividing the square of the size of the currently transmitted channel data by the square of the magnitude of all signals transmitted from the present by the length of the tap. This performs a function of averaging a large change in a signal input from a plurality of users, which serves to reduce a change in the signal of reference data applied to the comparators 132 and 134. The squarers 158 and 160 square the outputs of the dividers 154 and 156 and output them to the comparators 132 and 134, respectively, to obtain normalized power of the input I-channel and Q-channel data. The outputs of the squarers 158 and 160 become reference data of each I channel and Q channel for measuring an error amount of predistortion data.

Here, the operations of the squaring queue 152 and the dividers 154 and 156 may be expressed by the following equation.

The comparison data, which is another input of the comparators 132 and 134, is generated by feeding back part of the output signal of the power amplifier 116. This becomes data for obtaining error data for updating the value of the predistortion lookup table of the memory 146. The signal, which is partly combined in the output RF signal through the combiner 118, is demodulated by the demodulator 122 into the original I-channel and Q-channel data. Then, the low pass filters 124 and 126 low-pass filter the demodulated signals of the I and Q channels demodulated by the demodulator 122 to the baseband, and the analog / digital converters 128 and 130 respectively output the low pass filters 124 and 126. The filtered demodulated corresponding channel signals are converted into digital data and output. Then, the multipliers 166 and 168 multiply the data output from the analog / digital converters 128 and 130 by a first constant a, and the squarers 162 and 164 square the outputs of the multipliers 166 and 168 to obtain the comparators 132 and 134. Output as comparison data of each channel. Here, the first constants a and the second constant b input to the multipliers 166 and 168 and the multipliers 170 and 172 become values necessary for matching the magnitude of the transmitted signal and the magnitude of the received signal to the same level. The appropriate values of the constants a and b can be set.

The comparators 132 and 134 compare the input data of the corresponding channel output from the squarers 158 and 160 with the output data of the corresponding channel output from the squarers 162 and 164, respectively, and output the difference values as error data of the corresponding channel, respectively. do. That is, the input data is added to the predistortion data in the adders 140 and 142 and converted into predistorted data to compensate for the distortion that may occur in the transmission device in advance, and the final signal output through the power amplifier 116 of the transmission device. Is fed back to the comparison data of the comparators 132 and 134. In this case, when the reference data and the comparison data have the same value, the predistortion data is properly compensated for the amount of distortion of the transmission apparatus. When the reference data and the comparison data have different values, the predistortion data is transmitted. In this case, the amount of distortion of the apparatus cannot be properly compensated. In this case, the predistortion data must be updated by the corresponding error data to properly compensate for the amount of distortion of the transmitting apparatus in the next state.

Error data generated by the comparators 132 and 134 are input to multipliers 136 and 138, respectively, and the multipliers 136 and 138 determine the stability and convergence speed of the error data and adaptive predistortion algorithm of the corresponding channel. It is multiplied by the error correction coefficients μi and μq. The adders 140 and 142 add the I-channel and Q-channel predistortion data IWP and QWP output from the memory 146 and the outputs of the multipliers 136 and 138, respectively, which are updated and stored in the memory 146. The stored channel data is updated and stored in the predistortion lookup tables corresponding to the address position where the address generator 144 is generated.

So the next time the same input data is entered. The predistortion data multiplied by the input data of each channel is outputted with updated predistortion data. That is, the input data multiplied by the predistortion data of the corresponding channel in the multipliers 102 and 104 are converted into analog signals for transmission, and then unnecessary components other than the baseband are removed, and the power amplification after being modulated into RF signals. The final RF signal is output. In this case, in order to remove spectral distortion in the output spectrum generated due to nonlinearity of the power amplifier 116, as described above, a part of the output signal representing the nonlinear characteristic of the power amplifier 116 is feedback to compensate for the error value.

In the configuration of the embodiment of the present invention as shown in FIG. 2, the delayers 148 and 150 perform a function for synchronizing between the transmitted data and the received data, which can be experimentally specified and set to an appropriate value. In addition, the first constant a and the second constant b is a value necessary for matching the magnitudes of the transmission signal and the reception signal to the same level, which can also be selected as an appropriate value by experiment. The error correction coefficients mu i and mu q are coefficients for updating and storing the detected error data in the predistortion table, and can be set to appropriate values by experiments.

As described above, the method of implementing the adaptive predistortion algorithm according to the embodiment of the present invention can reduce the nonlinearity of the power amplifier in a system such as a CDMA base station having a large amplitude change of a signal input to a transmitter due to a plurality of user input signals. There is an advantage that can effectively reduce the distortion phenomenon in the output spectrum caused by. In addition, since all data processing is performed on baseband digital data, there is an advantage in terms of noise effect and accuracy compared to using an analog system, and in the method of generating an address, it can be processed in software. Even in hardware configuration can be simplified.

Claims (14)

In the power amplifier linearizer of the digital communication system, A waveform shaping filter for shaping and filtering the input data into a baseband signal; An address generator for generating an address corresponding to the input data; A memory having a predistortion lookup table for outputting predistortion data of an address position output from the address generator; A multiplier for generating predistorted data by multiplying the output of the waveform shaping filter by the output of the memory; A transmission unit having a power amplifier and outputting the predistorted data to output an output signal for compensating for distortion caused by nonlinearity of the power amplifier; A comparison data generator for generating a comparison data by feedback and demodulating the output signal and adjusting a level to a baseband transmission signal size; A reference data generator for delaying an output of the waveform shaping filter to synchronize with the feedback data and generating a reference data by adjusting the level of the delayed data to the magnitude of the feedback signal; And a correction data generator for calculating the difference between the reference data and the comparison data, obtaining the error data, and adding the error data to the output of the memory and updating and storing the error data in the predistortion lookup table of the corresponding address position. Power amplifier linearizer. The method of claim 1, wherein the comparison data generator, A combiner connected to an output terminal of the power amplifier to combine a part of an output signal to generate a feedback signal; A demodulator for demodulating the feedback signal; A low pass filter for filtering the demodulated signal to a baseband, A converter for converting the signal passed through the low pass filter into digital data; A multiplier for multiplying the digital data by a constant for adjusting the same size as the transmission signal; And a squarer for generating the comparison data by squaring the output of the multiplier. The method of claim 1 or 2, wherein the reference data generator, A delay unit for delaying the output of the waveform shaping filter to synchronize with the feedback signal; A multiplier for multiplying the delay data by a constant for adjusting the same amount as the feedback signal; And a squarer for generating the reference data by squaring the output of the multiplier. The method of claim 3, wherein the correction data generator, A comparator for generating error data by comparing the reference data with the comparison data; A multiplier for multiplying the error data by an error correction coefficient for determining stability and convergence speed of predistortion data; And an adder configured to add the predistortion data of the memory to the output of the multiplier and store the updated predistortion data in a predistortion lookup table corresponding to the current address position of the memory. Device. In the power amplifier linearizer of the digital communication system, A waveform shaping filter for shaping and filtering the input data into a baseband signal; An address generator for generating an address corresponding to the input data; A memory having a predistortion lookup table for outputting predistortion data of an address position output from the address generator; A multiplier for generating predistorted data by multiplying the output of the waveform shaping filter by the output of the memory; A transmission unit having a power amplifier and outputting the predistorted data to output an output signal for compensating for distortion caused by nonlinearity of the power amplifier; A comparison data generator for feedback and demodulating the output signal and adjusting the level to a baseband transmission signal to generate comparison data; A squaring queue having a memory element as long as a tap length of the waveform shaping filter, and storing data output from the waveform shaping filter and shifting previous data; Delay the output of the waveform shaping filter to synchronize with the feedback data, store the delayed data in the squared queue, adjust the level of the feedback signal, and divide the adjusted data by the squared queue value. A reference data generator for generating reference data averaging large changes in signals input from a plurality of users; And a correction data generator for calculating the difference between the reference data and the comparison data, obtaining the error data, and adding the error data to the output of the memory and updating and storing the error data in the predistortion lookup table of the corresponding address position. Power amplifier linearizer. The method of claim 5, wherein the comparison data generator, A combiner connected to an output terminal of the power amplifier to combine a part of an output signal to generate a feedback signal; A demodulator for demodulating the feedback signal; A low pass filter for filtering the demodulated signal to a baseband, A converter for converting the signal passed through the low pass filter into digital data; A multiplier for multiplying the digital data by a constant for adjusting the same size as the transmission signal; And a squarer for generating the comparison data by squaring the output of the multiplier. The method of claim 5 or 6, wherein the reference data generator, A delay unit for delaying the output of the waveform shaping filter to synchronize with the feedback signal; A first square that squares the output of the delay and stores the squared queue in the squared queue; A multiplier that multiplies the output of the squarer by a constant to adjust the output of the squarer to the same magnitude as the feedback signal; A divider for dividing the output of the multiplier by previous data shifted and outputted from the steering queue and averaging a large change in a signal input from a plurality of users to reduce a change in input data; And a second squarer for generating the reference data by squaring the output of the divider. 2. The method of claim 7, wherein the correction data generator, A comparator for generating error data by comparing the reference data with the comparison data; A multiplier for multiplying the error data by an error correction coefficient for determining stability and convergence speed of predistortion data; And an adder configured to add the predistortion data of the memory to the output of the multiplier and store the updated predistortion data in a predistortion lookup table corresponding to the current address position of the memory. Device. In the power amplifier linearization method of the digital communication system having a look-up table for storing the predistortion data in a position corresponding to the input data, Generating an address corresponding to the input data, outputting predistortion data from the lookup table, filtering the input data into a baseband signal, and performing waveform shaping; Generating a predistorted transmission data by multiplying the waveform-formed input data by the predistortion data; Converting the predistorted transmission data into an RF signal and outputting power amplification, and compensating for a distortion caused by nonlinearity such as a power amplifier during the amplification by the predistortion; Generating a comparison data by adjusting the level to the magnitude of the baseband transmission signal after demodulating the output signal and generating reference data by adjusting the level of the delayed input data to the magnitude of the feedback signal; And calculating the difference between the reference data and the comparison data, obtaining the error data, adding the error data to the predistortion data, and updating and storing the error data in the predistortion lookup table at the corresponding address position. Power amplifier linearization method. The method of claim 9, wherein the generating of the comparison data, Combining a part of the output signal to generate a feedback signal; Demodulating the feedback signal; Filtering the demodulated signal to a baseband; Converting the baseband filtered signal into digital data; Multiplying the digital data by a constant to adjust the same size as the transmission signal; Generating the comparison data by squaring the scaled data, The process of generating the reference data, Delaying the input data to synchronize with the feedback signal; Multiplying the delayed previous data by a constant to adjust the same amount as the feedback signal; And squaring the scaled data to generate the reference data. The method of claim 9 or 10, wherein the process of generating the correction data, Generating error data by comparing the reference data with the comparison data; Multiplying the error data by an error correction coefficient for determining stability and convergence speed of predistortion data; And adding the predistortion data to the error correction signal and storing the updated predistortion data in a predistortion lookup table corresponding to the current address position. A lookup table for storing predistortion data at a position corresponding to the input data, a waveform shaping filter for filtering the input data as a baseband signal, and a squaring queue having a memory element equal to the tap length of the waveform shaping filter. In the power amplifier linearization method of a digital communication system provided, Generating pre-distortion data from the lookup table by generating an address corresponding to the input data; Generating a predistorted transmission data by multiplying the waveform-formed input data by the predistortion data; Converting the predistorted transmission data into an RF signal and outputting power amplification, and compensating for a distortion caused by nonlinearity such as a power amplifier during the amplification by the predistortion; After the feedback signal is demodulated and demodulated, the level is adjusted to the size of the baseband transmission signal to generate comparison data. The delayed input data is stored in the squaring queue, and the delay data is shifted out of the squaring queue. Generating reference data by dividing the previous data and averaging a large change in the signal input from a plurality of users; And calculating the difference between the reference data and the comparison data, obtaining the error data, adding the error data to the predistortion data, and updating and storing the error data in the predistortion lookup table at the corresponding address position. Power amplifier linearization method. The method of claim 12, wherein the generating the comparison data, Combining a part of the output signal to generate a feedback signal; Demodulating the feedback signal; Filtering the demodulated signal to a baseband; Converting the baseband filtered signal into digital data; Multiplying the digital data by a constant to adjust the same size as the transmission signal; Generating the comparison data by squaring the scaled data, The process of generating the reference data, Delaying the input data to synchronize with the feedback signal; Squaring the delayed input data and applying it to the squaring queue; Multiplying the squared signal by a constant to adjust the same magnitude as the feedback signal; Dividing the input data multiplied by the constant by the previous data shifted and output from the squaring queue, and averaging a large change in a signal input from a plurality of users to reduce a change in the data; And dividing the divided input data to generate the reference data. The method of claim 13, wherein the generating of the correction data comprises: Generating error data by comparing the reference data with the comparison data; Multiplying the error data by an error correction coefficient that determines stability and convergence speed of predistortion data; And adding the predistortion data to the error correction signal and storing the updated predistortion data in a predistortion lookup table corresponding to the current address position.

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