JP2002084146A - Predistortion type distortion compensation power amplifier - Google Patents

Abstract

(57) [Summary] [Problem] D in a pre-distortion type power amplifier
A distortion compensation of a wideband signal is performed without being restricted by the sampling frequency of the A converter. A wideband signal is frequency-divided, and digital pre-distortion units are corresponding to each frequency.
04, and after the pre-distortion processing, each modulation unit 1
Up-converted to each frequency band at 31 to 134, these signals are combined at power combiner 51, and power amplifier 61
The inverse function characteristic of the input / output characteristic of is obtained. The combined signal is amplified by the power amplifier 61. Advantages By combining a plurality of digital input signals, a wideband signal can be arbitrarily generated, and a wideband distortion signal generated when a multicarrier is input to a power amplifier can be reduced. As a result, an amplifier having good linearity over a wide band can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion-compensated power amplifier, and more particularly to a predistortion-type distortion-compensated power amplifier suitable for high-frequency power amplification for radio communication equipment.

[0002]

2. Description of the Related Art In recent years, high-speed and high-multiplexing signal transmissions have been frequently used in wireless communication devices such as mobile communication devices, and the power of a plurality of carrier signals has been commonly amplified. Was. Such power amplifiers include:
Particularly high linearity is required to suppress deterioration of transmission characteristics.

However, generally, the input / output characteristics of a power amplifier show nonlinearity in a high-output portion as shown by a characteristic line 200 shown in FIG. Therefore, when the power amplifier is operated in a region where the nonlinearity is strong, nonlinear distortion occurs. Due to this nonlinear distortion, generation of adjacent channel leakage power,
In multi-carrier communication, intermodulation distortion occurs, causing a problem in that communication on other channels is disturbed and communication quality is degraded.

[0004] As one method of reducing distortion by compensating for nonlinearity of a power amplifier, a pre-distortion method is known. In the predistortion method, a signal having an inverse function characteristic as shown by a characteristic line 202 in FIG. 2 is generated with respect to a nonlinear input / output characteristic of the power amplifier as shown by a characteristic line 200 in FIG. By inputting, the input / output characteristics of the power amplifier are linearized as indicated by a characteristic line 201 indicated by a dotted line in FIG.

Conventionally, an inverse function characteristic of a power amplifier has been realized by approximation using a non-linear element such as a diode. However, recent advances in LSI technology have significantly improved the performance of processors and DACs. A pre-distortion method (digital pre-distortion) using processing technology has become applicable. The digital pre-distortion method can realize the inverse function characteristic of the power amplifier more precisely than the method using a nonlinear element, and thus can greatly reduce distortion.

FIG. 3 shows a block diagram of a conventional digital pre-distortion type distortion compensation power amplifier. The digital pre-distortion type distortion compensation power amplifier includes an input terminal 301, a pre-distortion section 302 including an operation section 303 and a storage section 304, a DAC 305 and an LP
The modulation section 310 includes a F306 and a mixer 307, a power amplifier 308, and an output terminal 309. An example of a digital pre-distortion type distortion compensation power amplifier having such a configuration is described in, for example, IEICE Transactions on Electronics, Vol.E80-C, NO.6 (June 1997), No. 78
2-787 (T. Matsuoka et al, “Compensation of Nonl
inear Distortion During Transmission Based on the
Adaptive Predistortion Method ”IEICE TRANS. ELECTR
ON., VOL.E80-C, NO.6 JUNE 1997).

The input digital signal is input to a pre-distortion section 302 through an input terminal 301. The arithmetic unit 303 of the pre-distortion unit 302 reads a distortion compensation coefficient stored in the storage unit 304 in advance using the input signal level as an address, and performs an arithmetic process on the input signal to thereby obtain a digital signal having an inverse function characteristic with the power amplifier 308. Generate This digital signal is output from the DAC 30
After being converted to an analog signal by 5 and passing through an LPF 306 for blocking unnecessary alias components, the signal is up-converted to a high frequency using a carrier by a mixer 307 as frequency conversion means. The output signal from mixer 307 is amplified to a predetermined power by power amplifier 308 and output from output terminal 309.

[0008] Here, based on the non-linear input / output characteristics of the power amplifier 308 measured in advance, the storage unit 304 stores a signal level of the input signal so that the arithmetic unit 303 can generate a signal having an inverse function characteristic. Is stored as an address. As a result, the arithmetic unit 303 can output a signal that is suitably corrected for the distortion signal, so that the input / output characteristics of the power amplifier 308 can be linearized and the distortion can be reduced. Note that reference numeral S30
Reference numeral 7 denotes a portion indicated by an arrow, i.e., the frequency of the horizontal axis and the power of the vertical axis, that is, the output signal of the mixer 307 schematically. The center part of the figure shows the power of the transmission frequency (single carrier signal), and the hatched parts on both sides show the generated adjacent channel leakage power. Similarly, S308 schematically shows the portion indicated by the arrow, that is, the transmission frequency of the output signal of the power amplifier 308 and the adjacent channel leakage power. As can be seen from S308 as compared with S307, in the output signal of the power amplifier 308, the transmission frequency power increases and the adjacent channel leakage power decreases. Also, in each of the drawings of the embodiments described later, the figures shown in the broken ellipse similarly schematically show the power of each signal in the portion indicated by the arrow.

[0009]

However, according to the predistortion-type distortion-compensating power amplifier using the above-mentioned conventional technique, when performing high-speed transmission or using a multi-carrier signal, the input signal band is limited to that of the DAC. That is, the processing band is exceeded and the band becomes wide, and sufficient distortion compensation cannot be performed. That is, when distortion compensation is performed on a wideband signal, it is necessary to increase the speed of the DAC.
Hz. Therefore, the signal band that can be processed by the sampling theorem is 100 MHz at the maximum. Further, considering the feasibility of the steepness of the aliasing LPF attenuation characteristic, the bandwidth of the analog signal that can be processed is limited to several tens of MHz at the maximum.

Therefore, the conventional digital predistortion type power amplifier can realize distortion compensation for a band of at most several tens of MHz, and distortion compensation for a wideband signal exceeding this range has not yet been put to practical use.

Accordingly, an object of the present invention is to provide a pre-distortion type which can perform sufficient distortion compensation even when the input signal band is wider than the DAC processing band when high-speed transmission or a multi-carrier signal is used. A distortion-compensating power amplifier is provided.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional digital pre-distortion type power amplifier, and is intended to perform distortion compensation of a wide band signal output from the power amplifier. In addition, the input signal to the power amplifier is divided into a plurality of frequency bands, digital pre-distortion processing is performed for each frequency band, and then converted to an analog signal before power combining. It is characterized by the following.
That is, a configuration in which a plurality of pre-distortion units, a plurality of modulation units, and a power combiner that adds and synthesizes all modulation unit outputs and outputs the combined output to the power amplifier is provided in a stage preceding the power amplifier.

[0013] This makes it possible to compensate for the narrowness of the analog signal band due to the processing speed of the DAC and to generate a wide band signal, so that the distortion signal output from the power amplifier can be compensated over a wide band. In addition, since a signal can be generated accurately at the same time, it is possible to provide a pre-distortion type distortion compensation power amplifier having good linearity.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a predistortion type distortion compensation power amplifier according to the present invention will be described in detail with reference to the accompanying drawings by way of specific examples. <Embodiment 1> FIG. 1 is a block diagram showing a first embodiment of the present invention, in which compensation is made for adjacent channel leakage power and tertiary intermodulation distortion generated when a two-carrier signal is amplified. This is an example of the configuration.

Assuming that the carrier frequencies corresponding to the digital signals input to the terminals 11 and 12 are ω1 and ω2, the frequencies ω3 and ω4 at which the third-order intermodulation distortion occurs are respectively ω1 and ω2.
3 = 2 × ω1−ω2 and ω4 = 2 × ω2−ω1. When performing distortion compensation for adjacent channel leakage power and third-order intermodulation distortion, signals corresponding to the four frequency bands ω1 to ω4 may be generated.

Therefore, in the present embodiment, the pre-distortion type distortion compensation power amplifiers are
And pre-distortion units 101-104, which are composed of
Modulators 131 to 134 comprising LPFs 21 to 24, LPFs 31 to 34, and mixers 41 to 44, a power combiner 51 for adding and combining output signals from the respective modulators, and an output from the power combiner 51 to a predetermined power. It comprises a power amplifier 61 for amplification and an output terminal 99 for outputting a signal from the power amplifier 61. Next, the operation of the distortion-compensated power amplifier according to the present embodiment thus configured will be described.

The storage units 121 to 124 previously calculate the inverse function characteristics from the input / output characteristics of the power amplifier 61 and store the distortion compensation coefficients using the levels of the digital signals input from the input terminals 11 and 12 as addresses. Keep it.

For example, since the output of the pre-distortion unit 101 is up-converted by the modulation unit 131 to the band of the frequency ω1, the storage unit 121 stores the distortion compensation coefficient for canceling the adjacent channel leakage power generated in the band of the frequency ω1. Is stored. Hereinafter, the frequency ω is also stored in the storage unit 122.
A distortion compensation coefficient for canceling adjacent channel leakage power generated in the second band is stored.

Similarly, since the output of the pre-distortion unit 103 is up-converted by the modulation unit 133 to the band of the frequency ω3, the storage unit 123 stores the third-order intermodulation distortion generated in the band of the frequency ω3. Various distortion compensation coefficients are stored. Hereinafter, the frequency ω is also stored in the storage unit 124.
A distortion compensation coefficient for canceling third-order intermodulation distortion occurring in the band No. 4 is stored.

The digital signals input from the input terminals 11 and 12 are input to arithmetic units 111 to 114, respectively. Each arithmetic unit reads the distortion compensation coefficient with the signal level as an address from the corresponding storage unit 121 to 124. Each input digital signal is subjected to arithmetic processing using a distortion correction coefficient, thereby generating a corrected digital signal (pre-distortion signal). Each operation unit 1
The pre-distortion signals output from 11 to 114 are converted into analog signals by DACs 21 to 24, respectively, and unnecessary alias components are removed by LPFs 31 to 34, respectively.
4 and the transmission frequencies ω1 to ω4 by the mixers 41 to 44.
Upconverted to

The signals output from the mixers 41 to 44 are combined by a power combiner 51 and input to a power amplifier 61. Since the input signal at this time is a signal having an inverse function characteristic of the nonlinear input / output characteristic of the power amplifier 61, the input signal is linearly amplified by the power amplifier 61 and the output terminal 9.
9 is output.

Here, an example of the distortion compensation coefficient stored in the storage units 121 to 124 will be described. As an example of the non-linear characteristic in the power amplifier 61, a non-linear function represented by the following equation (1) is assumed. This function has a linear gain of 10 times and 3
It has the following nonlinear term:

Vout = 10 Vin−0.1 Vin ³ (1) It is assumed that the instantaneous values of the amplitude of the input signal applied to the input terminals 11 and 12 at certain times are 0.4 and 0.5, respectively. If the pre-distortion described in this embodiment is not performed, the input signal to the power amplifier 61 is given by the following equation.
It is represented by (2).

Vin = 0.4cos (ω1 · t) + 0.5cos (ω2 · t) (2) The output of the power amplifier can be obtained by substituting equation (2) into equation (1) and rearranging it. When the obtained output is approximated by omitting the high-order distortion term, the following equation (3) is obtained.
Not only is the amplitude of the frequency component of
And ω4 have intermodulation distortion.

Vout = 3.802cos (ω1 · t) + 4.786cos (ω2 · t) −0.06cos (ω3 · t) −0.075cos (ω4 · t) (3) On the other hand, the predistortion according to the present embodiment is When performing the calculations, the calculation units 111 to 114 determine the input signal amplitudes at the terminals 11 and 12, and the instantaneous values thereof are 0.4 and 0.5, respectively.
Are stored in the storage units 121 to 12
4 and output. Here, as an example of the distortion compensation coefficient, it is assumed that the values shown in FIG. 9 are stored in the storage units.

As described above, the input signal to the power amplifier 61 is represented by the following equation (4).

Vin = 0.423742cos (ω1 · t) + 0.525486cos (ω2 · t) + 0.00795721cos (ω3 · t) + 0.00971801cos (ω4 · t) (4) This equation (4) is converted into equation (1). And the approximation with the higher-order distortion term omitted, the following equation (5) is obtained.

Vout = 4.00 cos (ω1 · t) +5.00 cos (ω2 · t) +0.00012 cos (ω3 · t) +0.0012 cos (ω4 · t) (5) The above equations (5) and (3) ), The amplitudes of the frequency components of ω1 and ω2 are not reduced, and the level of the intermodulation distortion is obviously reduced.

The values shown in FIG. 9 are merely examples in the case where the input amplitudes of the input terminals 11 and 12 are 0.4 and 0.5. However, the values shown in FIG. Even in this case, predistortion becomes possible by meticulously storing the distortion compensation coefficients corresponding to the respective input values in the storage unit.

The pre-distortion section that performs such an operation can be realized using a digital signal processor, and the same applies to the following embodiments.

In this embodiment, the case of compensating the third-order intermodulation distortion has been described. However, even with respect to the fifth-order or higher-order intermodulation distortion, the pre-distortion unit, the modulation unit, By adding a unit and making the frequency of the carrier used in each mixer correspond to the frequency of the higher-order intermodulation distortion signal, distortion compensation is possible. <Embodiment 2> FIG. 4 is a block diagram showing a second embodiment of the present invention, which compensates for adjacent channel leakage power and third-order intermodulation distortion generated when amplifying an equi-detuned three-carrier signal. This is a configuration example in the case of performing.

In this embodiment, an input terminal 10, an operation unit 110 and a storage unit 12 are added to the configuration of the embodiment shown in FIG.
0, a pre-distortion unit 100 and a modulation unit 1
30 (comprising the DAC 20, the LPF 30, and the mixer 40) is added, and a carrier having a frequency ω0 is input to the mixer 40.

In the storage unit 120, the inverse function characteristic is calculated in advance from the input / output characteristic of the power amplifier 61, and the input terminal 10
The distortion compensation coefficient is stored using the level of the digital signal input from .about.12 as an address. That is, since the output of predistortion section 100 is up-converted by modulation section 130 to the band of transmission frequency ω0, storage section 120 stores a distortion compensation coefficient for canceling adjacent channel leakage power generated in the band of ω0. deep.

Hereinafter, similarly to the case of the first embodiment,
The signals output from the mixers 40 to 44 are
1 are synthesized. This synthesized signal is supplied to the power amplifier 61
The signal has an inverse function characteristic of the nonlinear input / output characteristic of FIG. Therefore, the signal is amplified by the power amplifier 61 and becomes a signal with high linearity, and is output from the output terminal 99. That is, it is possible to compensate for adjacent channel leakage power and third-order intermodulation distortion in a three-carrier communication scheme with equal detuning.

In this embodiment, an example of a configuration for compensating for the third-order intermodulation distortion of the power amplifier with equal-tuning three-carrier distortion has been described. Even when compensating for intermodulation distortion, a pre-distortion unit and a modulation unit are appropriately added to the transmission frequency and intermodulation distortion frequency, respectively, and the carrier frequency used in each mixer is set to the transmission frequency or intermodulation distortion frequency. By making it correspond, distortion compensation is possible. <Embodiment 3> FIG. 5 is a block diagram showing a third embodiment of the present invention, which compensates for adjacent channel leakage power and third-order intermodulation distortion generated when a quadrature modulation two-carrier signal is amplified. This is a configuration example in the case of performing.

In the quadrature modulation system, one transmission frequency signal is formed of two signals (in-phase signal I and quadrature signal Q) orthogonal to each other. 508 are provided. Further, DACs 21 to 28 for converting output signals of the pre-distortion units 501 to 508 into analog signals, respectively.
LPFs 31 to 3 for removing unnecessary alias components
8 and quadrature modulators 511 to 514 for performing quadrature modulation.
Are arranged, and the carrier ω
By performing quadrature modulation using 1 to ω4, it is possible to compensate for adjacent channel leakage power and third-order intermodulation distortion for a quadrature modulation system two-carrier signal.

In this embodiment, the configuration example for compensating the third-order intermodulation distortion of the quadrature modulation system two-carrier distortion compensating power amplifier has been shown. Even when compensating for intermodulation distortion, the pre-distortion unit and the quadrature modulation unit are added as appropriate for the transmission frequency and intermodulation distortion frequency, and the carrier frequency used in each mixer is set to the transmission frequency and intermodulation distortion frequency. By making it correspond, distortion compensation is possible. <Embodiment 4> FIG. 6 is a block diagram showing a fourth embodiment of the present invention. Even when a characteristic change of a power amplifier occurs in a two-carrier distortion-compensated power amplifier, an adjacent channel follows the characteristic change. It is a configuration example in the case of compensating for leakage power and third-order intermodulation distortion.

In the present embodiment, in addition to the embodiment of FIG. 1, coefficient updating units 661 to 664 for updating distortion compensation coefficients stored in storage units 621 to 624, and power amplifier 6
1, a power divider 71 for extracting a part of the signal, mixers 45 to 48 for down-converting the output of the power divider 71, LPFs 641 to 644 for band-limiting the outputs of the mixers 45 to 48, and LPFs 641 to 644. And demodulation units 651 to 654 each including an ADC 81 to 84 for converting an output of the mixer into a digital signal.
Is the transmission frequency ω1 using the carrier waves ω1 to ω4, respectively.
The configuration is such that the signal components belonging to the band of ω4 to ω4 are demodulated and fed back to the respective coefficient update units 661 to 664.

With this configuration, the demodulation unit 6
The outputs of the carrier frequencies ω1, ω
2 are obtained, and demodulation sections 653 and 654 are obtained.
, Demodulated signals corresponding to the third-order intermodulation distortions ω3 and ω4 are obtained. At this time, the demodulation units 651, 65
Since the output signal of No. 2 includes the desired wave component and the residual adjacent channel leakage power component, the adjacent channel leakage power component can be extracted by calculating the difference between the input signal and the desired signal component. Similarly, residual third-order intermodulation distortion can be extracted from the output signals of the demodulation units 653 and 654.

The respective distortion compensation coefficients stored in the respective storage units 621 to 624 are updated via the respective coefficient update units 661 to 664 so that the residual distortion components extracted as described above become zero, and are updated. Predistortion is performed using the distortion compensation coefficient thus obtained. Thereafter, by repeating the steps of predistortion, residual distortion extraction, and distortion compensation coefficient updating, even if the nonlinear input / output characteristics of the power amplifier 61 fluctuate with time, the output distortion signal is changed according to the characteristics of the amplifier. And can be reduced.

In this embodiment, an example of the configuration of the power amplifier for compensating for the third-order intermodulation distortion of two carriers has been described. However, the number of carriers and the order of the distortion signal to be compensated are determined according to the second and third embodiments. By appropriately adding a pre-distortion section, a modulation section, and a demodulation section, it is possible to compensate for a fifth-order or higher-order intermodulation distortion in a multi-carrier signal of three or more carriers by following the characteristic change of the amplifier. is there. <Embodiment 5> FIG. 7 is a block diagram showing a fourth embodiment of the present invention, and is an example of a configuration in which the third-order intermodulation distortion of two carriers in a quadrature modulation system is compensated.

The point of difference from the configuration of FIG. 6 is that the present embodiment uses a quadrature modulated signal, so that the pre-distortion section 601 of FIG.
5 are provided with pre-distortion units 601 'to 608' each having a two-system configuration as shown in FIG. 5, that is, a configuration in which a calculation unit, a storage unit, and a coefficient update unit are each two sets. I and Q signals I1 'to I4', Q1 '
DAC21-28, LP corresponding to each of ~ Q4 '
F31 to F38 and quadrature modulators 511 to 514 for synthesizing signals respectively corresponding to the I and Q signals.

Further, when demodulating a signal, mixers 45 to 45 downconvert from high frequency to baseband.
48, the signals outside the desired band are removed by LPFs 641 to 644, and quadrature demodulated by quadrature demodulators 711 to 714 into I and Q signals I1 "to I4" and Q1 "to Q4", respectively. Are converted into digital signals. The output signals from the ADCs 81 to 88 are respectively supplied to the pre-distortion units 601 to
The data is input to 608 and pre-distorted.

In this embodiment, an example of the configuration of a power amplifier for compensating for the third-order intermodulation distortion of two carriers has been described. However, the number of carriers and the order of the distortion signal to be compensated are determined according to the second and third embodiments. By appropriately adding a pre-distortion section, a modulation section, and a demodulation section, it is possible to compensate for a fifth-order or higher-order intermodulation distortion in a multi-carrier signal of three or more carriers by following the characteristic change of the amplifier. is there.

As described above, even when the input digital signal is a quadrature modulation multi-carrier signal, higher-order distortion compensation can be performed by applying the quadrature demodulator to the demodulation unit. <Embodiment 6> FIG. 8 is a block diagram showing a sixth embodiment of the present invention. In this embodiment, a configuration example in which circuit blocks after the DAC are shared according to the processing band of the DAC to be used. It is. Various modifications are made possible by the common use.

For example, the DAC 2 used in FIG.
If the frequency bands 1 and 22 are wide enough to cover both the frequency bands ω1 and ω3, and both the bands ω2 and ω4, as shown in FIG.
The frequency-converted output signals from the second and third mixers are converted into intermediate frequencies (ω1-ωL1) and (ω3-ωL1) by mixers 41 and 42, respectively. These intermediate frequencies are transmitted to the power combiner 52.
To generate pre-distortion signals corresponding to both the bands ω1 and ω3.

Next, the output signal of the power combiner 52 is DA
After conversion into an analog signal by C21, unnecessary aliases are removed by the LPF 31 and up-converted by the mixer 45 using the carrier ωL1 to generate a high-frequency analog signal covering both the bands ω1 and ω3.

Similarly, the corrected output signals from the pre-distortion units 103 and 104 are also processed by the mixers 43 and 44 at the intermediate frequencies (ω2-ωL2) and (ω4-ωL), respectively.
2) frequency-converted and synthesized by the power synthesizer 53,
The LPF 32 converts the analog signal into an analog signal. The LPF 32 removes an unnecessary alias.
By up-conversion using the frequency ω2
Ω4 can be generated.

When this embodiment is applied, the DA used
It is possible to reduce the number of C, LPF and mixer by half compared with the embodiment of FIG.

In this embodiment, a DAC covering two bands has been described. However, if a DAC covering a wider band is used, the number of DACs, LPFs and mixers used can be reduced accordingly. is there. Further, this configuration is applicable not only to the embodiment of FIG. 1 but also to the embodiments of FIGS.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the spirit of the present invention. Of course.

[0052]

As is apparent from the above-described embodiment, according to the present invention, by combining a plurality of predistorted digital signals, a wide band signal can be obtained without being restricted by the processing band of the DAC. A signal can be arbitrarily generated, and a wideband distortion signal generated when a multicarrier is input to a power amplifier can be reduced.
As a result, distortion compensation for a wideband distortion signal output from the power amplifier becomes possible, and a power amplifier with good linearity can be formed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a distortion compensation power amplifier according to the present invention.

FIG. 2 is a diagram illustrating input / output nonlinearity of a general power amplifier and its inverse function characteristic.

FIG. 3 is a block diagram showing a configuration of a conventional digital predistortion type power amplifier.

FIG. 4 is a block diagram showing a second embodiment of the distortion compensation power amplifier according to the present invention.

FIG. 5 is a block diagram showing a third embodiment of the distortion-compensated power amplifier according to the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the distortion compensation power amplifier according to the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of the distortion compensation power amplifier according to the present invention.

FIG. 8 is a block diagram showing a sixth embodiment of the distortion-compensated power amplifier according to the present invention.

FIG. 9 is a diagram illustrating an example of a distortion compensation coefficient stored in a storage unit in FIG. 1;

[Explanation of symbols]

10-12 input terminals, 20-28 digital-to-analog converter (DAC), 30-38 low-pass filter (LPF), 40-48 mixer, 51-53 power combiner, 61 power amplifier, 71 ... power distributors, 81-
88: analog-to-digital converter (ADC), 99
... Output terminals, 100-104 pre-distortion units, 110-114 arithmetic units, 120-124 storage units, 130-134 modulation units, 200-202 characteristic lines, 301 input terminals, 302 pre-distortion units , 303: arithmetic unit, 304: storage unit, 305: DA
C, 306 LPF, 307 mixer, 308 power amplifier, 309 output terminal, 310 modulation section, 501 to 5
08: Predistortion section, 511 to 514: Quadrature modulator, 531 to 534: Quadrature modulation section, 601 to 608
... Pre-distortion section, 611-614 ... Calculation section,
621 to 624: storage unit, 631 to 634: modulation unit, 6
41 to 644... LPF, 651 to 654.
1 to 664... Coefficient updating unit, 711 to 714... Quadrature demodulator.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H04L 27/01 H04L 27/00 K 27/22 27/22 DF term (reference) 5J090 AA01 AA41 CA21 CA62 FA15 GN03 HN03 HN17 KA00 KA26 KA34 KA42 KA53 KA55 SA14 TA01 TA02 TA06 5J091 AA01 AA41 CA21 CA62 FA15 KA00 KA26 KA34 KA42 KA53 KA55 SA14 TA01 TA02 TA06 5K004 AA05 FA01 FF05 5K022 AA10A05 A06A05 A06A05

Claims (5)

[Claims] A plurality of digital pre-distortion units for performing pre-distortion processing on an input digital signal; and converting the pre-distorted input digital signal into frequency bands obtained by dividing a frequency band handled by a power amplifier into a plurality of frequency bands. A plurality of modulating units for respectively up-converting and outputting a modulated signal; a power combiner for adding and combining the up-converted modulated output signals; and amplifying a combined output signal of the power combiner to a predetermined power. A pre-distortion type distortion compensation power amplifier, comprising: the power amplifier. 2. A digital pre-distortion unit comprising: a storage unit in which a distortion compensation coefficient is stored in advance using a signal level of the input digital signal as an address; and a distortion compensation coefficient corresponding to the signal level of the input digital signal. An arithmetic unit that reads from a storage unit, performs arithmetic processing on the input digital signal, and generates a corrected digital signal having an inverse function characteristic with respect to the nonlinear characteristic of the power amplifier. Digital-to-analog converter (DA) that converts signals to analog signals
C), a low-pass filter (LPF) for blocking unnecessary alias components in the output signal of the DAC, and the LPF
2. A pre-distortion type distortion-compensating power amplifier according to claim 1, further comprising frequency conversion means for up-converting the output signal of the above-mentioned signal to a high frequency using a carrier. 3. A storage unit for storing at least one type of input digital signal and a distortion compensation coefficient in advance, and reading the distortion compensation coefficient from the storage unit according to a signal level of each of the input digital signals, A pre-distortion unit comprising an operation unit for performing a pre-distortion process by performing an operation process on an input digital signal and generating a corrected digital signal having an inverse function characteristic with respect to the nonlinear input / output characteristics of the power amplifier; and A DAC that converts the corrected digital signal into an analog signal, an LPF that blocks unnecessary alias components in the output signal of the DAC, and a frequency conversion unit that up-converts the output signal of the LPF to a high frequency using a carrier. And a plurality of modulation sections, A power combiner that adds and combines the outputs from the frequency converters to be converted, and a power amplifier that amplifies the output of the power combiner to a predetermined power. A predistortion-type distortion-compensating power amplifier, wherein a frequency is made to correspond to each frequency at which a transmission signal output from a power amplifier and an intermodulation distortion signal are arranged. 4. A pre-distortion unit for performing a pre-distortion process based on at least one type of input signal comprising a set of orthogonal digital signals orthogonal to each other, based on respective signal levels of the orthogonal digital signal, A DAC that converts an output signal from the unit into an analog signal, an LPF that blocks unnecessary alias components in the output signal from the DAC, and a carrier wave that outputs an output signal from the LPF corresponding to each of the quadrature digital signals. A plurality of modulators each comprising: a quadrature modulator that performs quadrature modulation by using; a power combiner that adds and combines outputs from all the quadrature modulators; and a power that amplifies an output of the power combiner to a predetermined power. Comprising an amplifier, the frequency of each carrier used in the quadrature modulator,
A predistortion-type distortion-compensating power amplifier, which is adapted to correspond to each frequency at which a transmission signal output from a power amplifier and an intermodulation distortion signal are arranged. 5. The pre-distortion type distortion-compensating power amplifier according to claim 1, wherein: a power divider for extracting a part of an output signal of the power amplifier; and a distribution from the power divider. Frequency conversion means for down-converting the output to a baseband band using a carrier, an LPF for blocking unnecessary high-frequency signal components in an output signal from the frequency conversion means for down-conversion,
And a plurality of demodulators for demodulating signal components in a frequency band generated by each of the arithmetic units. A predistortion-type distortion-compensated power amplifier for updating a distortion-compensation coefficient such that a distortion signal component included in an output signal of the unit is reduced.