Patent Publication Number: US-6904267-B2

Title: Amplifying device

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a mobile communication system, such as a portable telephone system, and in particular, to an amplifying device for use in a base station device. 
   2. Description of the Related Art 
   In the mobile communication system, such as the portable telephone system, a base station device is required to ensure arrival of a radio signal at a mobile station device which is located far from the base station device. Accordingly, it is necessary for the base station device to largely amplify a signal through an amplifier for transmitting it. 
   In the foregoing mobile communication system, the W-CDMA (Wide-band Code Division Multiple Access) system and so on have been adopted as mobile communication systems. 
   However, since an amplifier is an analog device, its input-output characteristics form a nonlinear function. Particularly, after exceeding the amplification limit point called a saturation point, the output power remains nearly constant even if the power inputted to the amplifier increases. 
   This nonlinear output causes nonlinear distortion. In case of a transmission signal before amplification, a signal component outside a desired signal band is suppressed to a low level through a band limiting filter. On the other hand, in case of a signal after passing the amplifier, nonlinear distortion is generated so that a signal component leaks to the exterior of the desired signal band (adjacent channels). This causes a phenomenon that the power spectrum expands to the adjacent channels. 
   As described above, since the transmission power is high in the base station device, the magnitude of the leak power to the adjacent channels is strictly regulated. Under these circumstances, it has been a large problem how to reduce the foregoing adjacent channel leak power. 
   For amplifying the transmission power while reducing the adjacent channel leak power, a distortion compensation amplifying device using the predistortion technique has been provided in the base station device for amplifying the transmission power. 
   The conventional distortion compensation amplifying device using the predistortion technique is described in JP-A-2000-151295 for “DISTORTION COMPENSATION CIRCUIT” published on May 30, 2000 (Applicant: Mitsubishi Electric Corporation; Inventors: Kenichi Horiguchi and others). 
   In this prior art, a portion of an input signal inputted to a signal path having a vector adjuster, a linearizer and an amplifier and a portion of an output signal outputted from the amplifier are respectively extracted, and a combined power level of these signals is detected, and then, based on a detection result, a bias adjustment of the linearizer and an adjustment of the vector adjuster are carried out so as to minimize the power level. 
   However, there has been a problem that the foregoing conventional distortion compensation amplifying device is increased in size, weight and cost. 
   Specifically, analog delay lines used in the conventional distortion compensation amplifying device are large in area and weight and high in cost, and thus exert an influence even on the body of the amplifying device. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in view of the above, and has an object to provide an amplifying device with reduced size, weight and cost. 
   For solving the foregoing problem of the prior art, according to the present invention, there is provided an amplifying device, wherein a digital delay section for digital-delaying an input signal per carrier for a constant time is provided in a main signal system or a control system instead of an analog delay line, phases of signals in the main signal system and the control system are controlled in a phase control section, and a distortion compensating section gives distortion compensation to a multi-carrier signal for canceling a nonlinear characteristic generated in an amplifying section, based on a power value and an output from a distributing section. Therefore, the amplifying device according to the present invention requires no analog delay lines, and thus can be provided with reduced size, weight and cost. 
   Alternatively, in an amplifying device of the present invention, a digital delay section for digital-delaying an input signal per carrier for a constant time is provided in a main signal system or a control system instead of an analog delay line, phases of signals in the main signal system and the control system are controlled in a phase control section, and a distortion compensating section controls a multi-carrier signal for reducing an error between the demodulated contents of outputs from a coupling section and a distributing section relative to a power value. Therefore, the amplifying device requires no analog delay lines, and thus can be provided with reduced size, weight and cost. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 2  is a structural block diagram of a predistorter  109 . 
       FIG. 3  is a structural block diagram of a predistorter  109 ′. 
       FIG. 4  is a second structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 5  is a third structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 6  is a fourth structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 7  is a fifth structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 8  is a sixth structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
       FIG. 9  is a seventh structural block diagram of a distortion compensation amplifying device according to an embodiment of the present invention. 
   

   DESCRIPTION OF REFERENCE NUMERALS 
     101  . . . D/A converter,  102  . . . orthogonal modulator,  103 ,  126  . . . VCO,  104 ,  127  . . . mixer,  105  . . . coupler,  107  . . . power detecting section,  109 ,  109 ′ . . . predistorter,  110  . . . amplifier,  111  . . . distributor,  113  . . . carrier offset section,  114  . . . adding section,  115  . . . up-convert section,  116  . . . phase control section,  117  . . . digital orthogonal modulator,  121 - 1  . . . attenuation control section,  121 - 2  . . . phase control section,  122 - 1 ,  122 - 2  . . . D/A converter,  123  . . . attenuator,  124  . . . phasing device,  125 ,  125 ′ . . . table producing section,  128  . . . LPF,  129  . . . A/D converter,  130 - 1 ,  130 - 2  . . . demodulating section,  131  . . . comparing section 
   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described hereinbelow with reference to the accompanying drawings. 
   In an amplifying device according to the embodiment of the present invention, a digital delay section for digital-delaying an input signal per carrier for a constant time is provided in a main signal system or a control system instead of an analog delay line, phases of signals in the main signal system and the control system are controlled in a phase control section, and a distortion compensating section gives distortion compensation to a multi-carrier signal for canceling a nonlinear characteristic generated in an amplifying section, based on a power value and an output from a distributing section. Therefore, the amplifying device according to the embodiment of the present invention requires no analog delay lines, and thus can be provided with reduced size, weight and cost. 
   Orthogonal modulating sections in claims correspond to analog orthogonal modulators or digital orthogonal modulators, a coupling section to a coupler, an amplifying section to an amplifier, a distributing section to a distributor, and a distortion compensating section to a predistorter. 
   A structure of an amplifying device according to the embodiment of the present invention will be described referring to FIG.  1 .  FIG. 1  is a first structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. 
   Like the prior art, the amplifying device of  FIG. 1  uses the predistortion technique and applies an amplification process to input signals of respective carriers in the form of digital signals. In the distortion compensation amplifying device of  FIG. 1 , the number of carriers is 4. However, the number of carriers of input signals may be set to a different value. 
   The amplifying device of  FIG. 1  comprises digital delay sections  112 , D/A converters (D/A in the figure)  101 , orthogonal modulators  102 , an up-convert section  115 , a coupler  105 , carrier offset sections  113 , an adding section  114 , a power detecting section  107 , a phase control section  116 , a predistorter  109 , an amplifier (PA (Power Amplifier) in the figure)  110  and a distributor  111 . 
   The up-convert section  115  comprises VCOs (Voltage Controlled Oscillators)  103  and mixers  104 . 
   In the amplifying device of  FIG. 1 , the digital delay section  112 , the D/A converter  101 , the orthogonal modulator  102 , the VCO  103  and the mixer  104  of the up-convert section  115 , and the carrier offset section  113  are provided per carrier of the input signal. 
   Each digital delay section  112  digital-delays the input signal for a constant time and outputs it to the D/A converter  101  of the corresponding carrier. Each digital delay section  112  is constituted using, for example, a memory buffer. 
   Each D/A converter  101  converts the input signal in the form of the digital signal into an analog signal and outputs it to the orthogonal modulator  102  of the corresponding carrier. 
   Each orthogonal modulator  102  performs orthogonal modulation of the input signal converted to the analog signal and outputs it to the up-convert section  115 . 
   The up-convert section  115  up-converts the orthogonal-converted input signal to an RF frequency (Radio Frequency) and outputs it to the coupler  105 . 
   In the up-convert section  115 , the VCO  103  and the mixer  104  are provided per carrier, and the mixer  104  carries out frequency conversion according to a carrier frequency outputted from the VCO  103 , then necessary band limitation is performed using a band limiting filter (not shown) or the like. Further, according to the timing of phase control signals outputted from the phase control section  116 , the VCOs  103  output frequencies which differ per carrier. 
   The coupler  105  combines RF signals of the respective carriers outputted from the up-convert section  115  to produce a multi-carrier signal and outputs it to the predistorter  109 . 
   Each carrier offset section  113  applies offset rotation corresponding to a carrier frequency difference (detuning frequency) to the input signal of the corresponding carrier in the form of digital data and outputs it to the adding section  114 . 
   The carrier offset sections  113  perform offset rotation processing of the respective carriers based on the timing of phase control signals outputted from the phase control section  116 . Each carrier offset section  113  may be constituted of, for example, a complex multiplier. 
   The adding section  114  adds together the input signals of the respective carriers subjected to the offset rotation and outputs it to the power detecting section  107 . 
   The power detecting section  107  detects a power value by calculating the power value based on the summed input signal, and outputs the detected power value to the predistorter  109  as a power value signal. 
   The phase control section  116  outputs the control signals to the VCOs  103  of the up-convert section  115  and the carrier offset section  113 , thereby to control the output timing of the carrier frequencies and the timing of the offset rotation processing of the input signals. 
   The phase control section  116  may be arranged to use, for example, a clock generator, and output the control signals synchronously with a clock frequency. 
   The predistorter  109  executes a control of giving a distortion compensation characteristic, relative to the multi-carrier signal inputted from the coupler  105 , and outputs it to the PA  110 . 
   The predistorter  109  gives such a distortion compensation characteristic that cancels a nonlinear characteristic generated in the PA  110 , based on the power value signal outputted from the power detecting section  107  and the amplified multi-carrier signal outputted from the distributor  111 . 
   The amplifier (PA)  110  amplifies the multi-carrier signal and outputs it. 
   The distributor  111  carries out distribution of the amplified multi-carrier signal outputted from the amplifier  110  so as to output it to the exterior and feedback it to the predistorter  109 . 
   Now, a structure of the predistorter  109  will be described referring to FIG.  2 .  FIG. 2  is a structural block diagram of the predistorter  109  in the distortion compensation amplifying device according to the embodiment of the present invention. 
   The predistorter  109  comprises an attenuation control section  121 - 1 , a phase control section  121 - 2 , D/A converters (D/A in the figure)  122 - 1  and  122 - 2 , an attenuator  123 , a phasing device  124 , a table producing section  125 , a VCO  126 , a mixer  127 , an LPF (Low Pass Filter)  128 , and an A/D converter (A/D in the figure). 
   In  FIG. 2 , the positioning order of the attenuator  123  and the phasing device  124  may be changed. 
   The attenuation control section  121 - 1  stores therein an LUT (Look Up Table) showing a relationship between power values and attenuations reflecting distortion compensation characteristics, refers to the LUT based on the inputted power value signal, and outputs an attenuation control signal corresponding to a reference result to the D/A converter  122 - 1 . 
   Further, based on a control command from the table producing section  125 , the attenuation control section  121 - 1  updates the LUT to adjust attenuations. 
   The phase control section  121 - 2  stores therein an LUT showing a relationship between power values and phase control amounts reflecting distortion compensation characteristics, refers to the LUT based on the inputted power value signal, and outputs a phase control signal corresponding to a reference result to the D/A converter  122 - 2 . 
   Further, based on a control command from the table producing section  125 , the phase control section  121 - 2  updates the LUT to adjust phase control amounts. 
   The D/A converters  122 - 1  and  122 - 2  respectively convert the attenuation control signal outputted from the attenuation control section  121 - 1  and the phase control signal outputted from the phase control section  121 - 2  into analog signals, and output them to the attenuator  123  and the phasing device  124 . 
   Based on the attenuation control signal outputted from the attenuation control section  121 - 1  and analog-converted in the D/A converter  122 - 1 , the attenuator  123  carries out attenuation processing corresponding to a distortion compensation characteristic relative to the inputted multi-carrier signal. 
   Based on the phase control signal outputted from the phase control section  121 - 2  and analog-converted in the D/A converter  122 - 2 , the phasing device  124  carries out phase control processing corresponding to a distortion compensation characteristic relative to the inputted multi-carrier signal. 
   Based on a distortion component extracted from the amplified multi-carrier signal outputted from the amplifier  110  and fed back from the distributor  111 , the table producing section  125  outputs the control commands to the attenuation control section  121 - 1  and the phase control section  121 - 2  for updating the LUTs stored in the attenuation control section  121 - 1  and the phase control section  121 - 2 , respectively. 
   Further, the table producing section  125  outputs a control signal to the VCO  126  for controlling a frequency for distortion component extraction. 
   In the predistorter of  FIG. 2 , the table producing section  125  may be constituted using a DSP (Digital Signal Processor) or the like. 
   Based on the control signal outputted from the table producing section  125 , the VCO  126  outputs the frequency for distortion component extraction to the mixer  127 . 
   The mixer  127  performs frequency conversion of the amplified multi-carrier signal fed back from the distributor  111  to convert it to the frequency outputted from the VCO  126 . 
   When the amplified multi-carrier signal subjected to the frequency conversion passes through the LPF  128 , the LPF  128  attenuates frequency components above a constant value and extracts a distortion component. 
   In the predistorter of  FIG. 2 , a BPF (Band Pass Filter) may be used instead of the LPF  128 . 
   The A/D converter  129  digital-converts the distortion component extracted in the LPF  128 , and outputs it to the table producing section  125  as a digital signal. 
   Now, an operation of the distortion compensation amplifying device according to the embodiment of the present invention will be described referring to  FIGS. 1 and 2 . 
   In the amplifying device of  FIG. 1 , the input signal of each carrier is bifurcated and inputted to the corresponding digital delay section and the corresponding carrier offset section  113 . 
   Hereinafter, in the amplifying device of  FIG. 1 , a series of circuits from the digital delay sections  112  to the coupler  105  will be referred to as a main signal system, and a series of circuits from the carrier offset sections  113  to the power detecting section  107  will be referred to as a control system. 
   First, an operation of the main signal system will be described. The input signal of each carrier inputted to the digital delay section  112  is digital-delayed for a constant time, and then, outputted to the D/A converter  101 . The digital delay section  112  corresponds to the conventional analog delay line, wherein a delay amount of the input signal is set for matching the timings of the main signal system and the control system in the predistorter  109 . 
   The input signal is converted to the analog signal in the D/A converter  101 , then is subjected to the orthogonal modulation in the orthogonal modulator  102 . The D/A converter  101  and the orthogonal modulator  102  are also provided per carrier, and perform the foregoing processing relative to the input signal of the corresponding carrier. 
   The input signal of each carrier subjected to the orthogonal modulation is inputted to the up-convert section  115 . 
   In the up-convert section  115 , the VCO  103  and the mixer  104  are provided in pair per carrier. The input signal of each carrier is converted by the corresponding mixer  104  to the carrier frequency outputted from the VCO  103  forming the pair, thereby to be up-converted to the RF frequency. 
   The input signals of the respective carriers up-converted in the up-convert section  115  are inputted to the coupler  105 . The input signals inputted to the coupler  105  are combined and outputted to the predistorter  109  as a multi-carrier signal. 
   Now, an operation of the control system will be described. 
   The input signal of each carrier inputted to the carrier offset section  113  is subjected to the offset rotation processing corresponding to a carrier frequency difference. 
   For example, when the carrier frequencies of the respective carriers are 2000 MHz, 2005 MHz, 2010 MHz and 2015 MHz, the carrier offset sections  113  corresponding to the respective carriers apply offset rotation of 0 MHz, 5 MHz, 10 MHz and 15 MHz to the input signals. Specifically, in the carrier offset sections  113 , the offset rotation processing is executed for the input signals so that the carrier frequencies of the respective carriers become equal to each other after the offset rotation processing. 
   The input signals of the respective carriers subjected to the offset rotation processing are outputted to the adding section  114  where they are added together, and then outputted to the power detecting section  107 . The power detecting section  107  detects a power value by calculating the power value based on the summed input signal. The power detecting section  107  outputs the detected power value to the predistorter  109  as a power value signal. 
   In the power detecting section  107 , assuming that a voltage of an in-phase component of the input signal is I and a voltage of a quadrature component thereof is Q, the power can be derived by calculating I 2 +Q 2 . 
   The multi-carrier signal outputted from the coupler  195  of the main signal system and the power value signal outputted from the power detecting section  107  of the control system are inputted to the predistorter  109 . Based on the inputted power value signal, the predistorter  109  executes a control of giving a distortion compensation characteristic to the multi-carrier signal. 
   In the amplifying device of  FIG. 1 , for coping with the power detection through the digital processing, the circuit is bifurcated to the main signal system and the control system, wherein the generation of the multi-carrier signal based on the analog input signal in the main signal system and the detection of the power value using the digital input signal in the control system are carried out independently of each other. In the amplifying device of  FIG. 1 , the phase control section  116  is provided for ensuring synchronization in phase between these two different systems upon the conversion of the input signals to the carrier frequencies. 
   Upon executing the control of accurately giving the distortion compensation characteristic, it is necessary for the predistorter  109  that the output phase of the carrier frequency and the phase for giving the offset rotation agree with each other. Accordingly, in the amplifying device of  FIG. 1 , the phase control section  116  outputs the control signals to the VCOs  103  of the up-convert section  115  and the carrier offset sections  13  and, synchronously with the timing of the control signals, the VCOs  103  perform the control of outputting the carrier frequencies and the carrier offset sections  113  perform the control of executing the offset rotation processing. With this arrangement, the phases of the foregoing two processings can be matched with each other, so that the predistorter  109  can give the distortion compensation characteristic based on the accurate power value of the multi-carrier signal. 
   Hereinbelow, an operation of the predistorter  109  will be described referring to FIG.  2 . As shown in  FIG. 2 , in the predistorter  109 , the power value signal is inputted to the attenuation control section  121 - 1  and the phase control section  121 - 2 . The attenuation control section  121 - 1  and the phase control section  121 - 2  respectively store the LUT showing the relationship between power values and attenuations and the LUT showing the relationship between power values and phase control amounts. In each control section, the attenuation or phase control amount reflecting the distortion compensation characteristic can be specified by referring to the LUT based on the power value. 
   In the attenuation control section  121 - 1 , when the LUT is referred to based on the inputted power value to specify the corresponding attenuation, the attenuation is outputted to the D/A converter  122 - 1  as the attenuation control signal. In the D/A converter  122 - 1 , the attenuation control signal is analog-converted and outputted to the attenuator  123 . In the attenuator  123 , based on the inputted attenuation control signal, the attenuation processing of the multi-carrier signal reflecting the distortion compensation characteristic is carried out. 
   In the phase control section  121 - 2 , when the LUT is referred to based on the inputted power value to specify the corresponding phase control amount, the phase control amount is outputted to the D/A converter  122 - 2  as the phase control signal. In the D/A converter  122 - 2 , the phase control signal is analog-converted and outputted to the phasing device  124 . In the phasing device  124 , based on the inputted phase control signal, the phase control processing of the multi-carrier signal reflecting the distortion compensation characteristic is carried out. 
   The multi-carrier signal, given the distortion compensation characteristic through the attenuation processing and the phase control processing, is outputted to the amplifier  110 . The amplifier  110  amplifies the inputted multi-carrier signal and outputs it to the exterior. Since the multi-carrier signal is given the distortion compensation characteristic having an inverse characteristic of the nonlinear characteristic generated in the amplifier  110 , the multi-carrier signal is theoretically amplified without distortion. 
   The amplified multi-carrier signal is, other than outputted to the exterior, also fed back to the predistorter  109  from the distributor  111 . 
   The nonlinear characteristic of the amplifier  110  changes due to aged deterioration, temperature characteristics or the like, so that there arises a case where the distortion can not be compensated by the distortion compensation characteristic given in the predistorter  109 . Accordingly, the predistorter  109  carries out adaptive predistortion wherein a distortion component remaining without compensation is extracted from the fed-back amplified multi-carrier signal, and the distortion compensation characteristic is corrected based on the extracted distortion component so as to be adapted to a change of the nonlinear characteristic. 
   The amplified multi-carrier signal fed back from the distributor  111  is inputted to the mixer  127  in the predistorter  109 . The mixer  127  performs frequency conversion of the inputted signal to convert it to the frequency outputted from the VCO  126 , and outputs it to the LPF  128 . With respect to the multi-carrier signal subjected to the frequency conversion, the LPF  128  attenuates frequency components above a constant frequency, thereby to extract a distortion component. The extracted distortion component is inputted to the A/D converter  129  as a distortion component signal so as to be digital-converted. 
   The digital-converted distortion component signal is inputted to the table producing section  125 . Based on the inputted distortion component signal, the table producing section  125  outputs the control commands to the attenuation control section  121 - 1  and the phase control section  121 - 2  for updating the LUTs stored in the respective control sections so as to minimize the distortion component. 
   The attenuation control section  121 - 1  and the phase control section  121 - 2  respectively update the LUTs based on the inputted control commands to adjust the attenuations and the phase control amounts. Thereafter, in the respective control sections, the attenuation processing and the phase control processing of the multi-carrier signal are performed based on the updated LUTs, so that the distortion compensation characteristic adapted to the change of the nonlinear characteristic can be given. 
   The table producing section  125  outputs the control signal to the VCO  126 . According to the control signal, the VCO  126  updates the frequency for the distortion component extraction. 
   The predistorter  109  of  FIG. 2  performs the adaptive predistortion for extracting the distortion component. As other adaptive predistortion, the table producing section  125  may demodulate the fed-back amplified multi-carrier signal and compare it with the multi-carrier signal outputted from the coupler  105 , and then, update the LUTs of the attenuation control section  121 - 1  and the phase control section  121 - 2  so as to minimize an error. 
   A structure and operation of a predistorter which performs the foregoing control will be described referring to  FIG. 3 , with respect to mainly a difference as compared with the predistorter of FIG.  2 .  FIG. 3  is a structural block diagram of another predistorter for use in the distortion compensation amplifying device according to the embodiment of the present invention. Explanation will be made by assigning the same reference signs to portions having the same structure as the predistorter of FIG.  2 . 
   As compared with the predistorter of  FIG. 2 , a difference resides in that a predistorter  109 ′ of  FIG. 3  includes a demodulating section  130 - 1  for demodulating the multi-carrier signal outputted from the coupler  105 , a demodulating section  130 - 2  for demodulating the multi-carrier signal fed back from the distributor  111 , a comparing section  131  for comparing the demodulated contents in the demodulating sections  130 - 1  and  130 - 2  to output a comparison result to a table producing section  125 ′, and the table producing section  125 ′ for outputting, based on the comparison result outputted from the comparing section  131 , control commands for updating the LUTs stored in the attenuation control section  121 - 1  and the phase control section  121 - 2 , to the respective control sections  121 - 1  and  121 - 2 . 
   In the predistorter  109 ′ of  FIG. 3 , the demodulating section  130 - 1  demodulates the multi-carrier signal outputted from the coupler  105 , and outputs the demodulated contents (envelope detection contents) to the comparing section  131 . The demodulating section  130 - 2  demodulates the multi-carrier signal fed back from the distributor  111 , and outputs the demodulated contents to the comparing section  131 . 
   The comparing section  131  includes therein a memory and digital-converts the demodulated contents outputted from the demodulating sections  130 - 1  and  130 - 2  for storage in the memory. Then, the comparing section  131  multiplies the demodulated contents (envelope detected data) from the demodulating section  130 - 1  by an amplification factor of the PA  110 , and stores it in the memory. This causes the demodulated contents (demodulated input data subjected to the multiplication) in the demodulating section  130 - 1  and the demodulated contents (demodulated fed-back data) in the demodulating section  130 - 2  to be signals of the same level. 
   In the comparing section  131 , a time required for the input signal from entering the PA  110  for amplification to feeding back from the distributor  111  is set in advance. The comparing section  131  reads from the memory the demodulated fed-back data and the demodulated input data subjected to the multiplication which was stored earlier than the demodulated fed-back data by the set time, and compares them. With this processing, the comparing section  131  can compare the input data and the fed-back data by matching the timing. 
   The comparison result about the demodulated contents in the comparing section  131  is outputted to the table producing section  125 ′. The table producing section  125 ′ judges an error based on the comparison result, and outputs control signals to the attenuation control section  121 - 1  and the phase control section  121 - 2  for updating the LUTs stored in the respective control sections so as to minimize the error. 
   The attenuation control section  121 - 1  and the phase control section  121 - 2  respectively update the LUTs based on the inputted control commands to adjust the attenuations and the phase control amounts. Thereafter, the respective control sections carry out the attenuation processing and the phase control processing of the multi-carrier signal based on the update LUTs, so that a control which can reduce an error of the demodulated contents is made possible. 
   In the amplifying device of  FIG. 1 , if the predistorter  109  is not adaptive, i.e. does not perform the adaptive predistortion, and thus no feedback of the multi-carrier signal is required, the distributor  111  is not necessary. 
   In accordance with the distortion compensation amplifying device according to the embodiment of the present invention, the input signals are delayed using the digital delay sections  112  in the main signal system, and the offset rotation processing and the power detection are carried out using the digital input signals in the control system, thereby to ensure the synchronization in phase between the multi-carrier signal in the main signal system and the power value signal in the control system. Therefore, the conventionally used analog delay lines become unnecessary, so that there can be provided the amplifying device which is reduced in size, weight and cost. 
   Now, other structures of distortion compensation amplifying devices according to the embodiments of the present invention will be described referring to figures, with respect to mainly differences as compared with the distortion compensation amplifying device of FIG.  1 . Explanation will be made by assigning the same reference signs to portions having the same structure as those in FIG.  1 . 
     FIG. 4  is a second structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 4 , the digital delay sections  112  are provided on an input side of the carrier offset sections  113  in the control system. 
   The structure of the amplifying device shown in  FIG. 4  is effective when a time required for the generation of the multi-carrier signal in the main signal system is greater than a time required for the power value detection in the control system. In the amplifying device of  FIG. 4 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
   According to the amplifying device of  FIG. 4 , even when the time required for the generation of the multi-carrier signal is greater than the time required for the power value detection, the distortion compensation of the amplifier can be accurately performed. 
     FIG. 5  is a third structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 5 , the positioning order of the digital delay sections  112  and the carrier offset sections  113  are changed in the amplifying device of FIG.  4 . Even in such a structure, since the time required for the power value detection in the control system is unchanged, the amplifying device of  FIG. 5  can achieve the distortion compensation of the amplifier accurately. In the amplifying device of  FIG. 5 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
     FIG. 6  is a fourth structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 6 , the digital orthogonal modulators  117  are provided on an input side of the digital delay sections  112 , instead of the orthogonal modulators  102 . The digital orthogonal modulator  117  performs orthogonal modulation of the digital input signal, and an operation thereof is the same as that of the orthogonal modulator of FIG.  1 . The digital orthogonal modulator  117  is also provided per carrier. In the amplifying device of  FIG. 6 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
     FIG. 7  is a fifth structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 7 , the positioning order of the digital orthogonal modulators and the digital delay sections  112  are changed in the amplifying device of FIG.  6 . In the amplifying device of  FIG. 7 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
     FIG. 8  is a sixth structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 8 , the digital delay sections  112  are provided on an input side o the carrier offset sections  113  in the amplifying device of FIG.  6 . 
   The structure of the amplifying device shown in  FIG. 8  is effective when a time required for the generation of the multi-carrier signal in the main signal system is greater than a time required for the power value detection in the control system. In the amplifying device of  FIG. 8 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
   According to the amplifying device of  FIG. 8 , even when the time required for the generation of the multi-carrier signal is greater than the time required for the power value detection, the distortion compensation of the amplifier can be accurately performed. 
     FIG. 9  is a seventh structural block diagram of a distortion compensation amplifying device according to the embodiment of the present invention. In the amplifying device of  FIG. 9 , the positioning order of the digital delay sections  112  and the carrier offset sections  113  are changed in the amplifying device of FIG.  8 . Even in such a structure, since the time required for the power value detection in the control system is unchanged, the amplifying device of  FIG. 9  can achieve the distortion compensation of the amplifier accurately. In the amplifying device of  FIG. 9 , the predistorter  109 ′ shown in  FIG. 3  may be used instead of the predistorter  109 . 
   According to the present invention, there is provided an amplifying device, wherein a digital delay section for digital-delaying an input signal per carrier for a constant time is provided in a main signal system or a control system instead of an analog delay line, phases of signals in the main signal system and the control system are controlled in a phase control section, and a distortion compensating section gives distortion compensation to a multi-carrier signal for canceling a nonlinear characteristic generated in an amplifying section, based on a power value and a portion of an output from a distributing section. Therefore, the amplifying device according to the present invention requires no analog delay lines, and thus can be provided with reduced size, weight and cost. 
   Further, there is also provided an amplifying device, wherein a digital delay section for digital-delaying an input signal per carrier for a constant time is provided in a main signal system or a control system instead of an analog delay line, phases of signals in the main signal system and the control system are controlled in a phase control section, and a distortion compensating section performs a control relative to a multi-carrier signal for reducing an error between the respective demodulated contents based on a power value and an output from a distributing section. Therefore, the amplifying device requires no analog delay lines, and thus can be provided with reduced size, weight and cost.