JP2002043861A - Distortion compensating method and distortion compensation amplifying circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion compensation amplifying circuit that prevents wrong distortion compensation from being optimized and adjusted, when the level of an input signal is reduced. SOLUTION: A distributor 1 allows the input signal to branch into two paths. A vector adjustment circuit 2 allows one signal to be subjected to vector adjustment. A main amplifier 3 amplifies the result. A delay line 5 allows the other to be subjected to phase adjustment. A delay line 9 is subjected to the phase adjustment, after a pilot signal is injected by the output of the main amplifier 3. A vector adjustment circuit 10 is subjected to phase adjustment after the output of the delay line 5, and the signal that is allowed to branch from the output of the main amplifier 3 are multiplexed. An auxiliary amplifier 11 amplifies the resultant signal. A control part 13 detects the level of the input signal, the output of the auxiliary amplifier 11, and a multiplexed output signal, and fixes the amount of attenuation and phase shift in the vector adjustment circuit 2 of at least a distortion extraction loop by control data; while the level of the input signal is high, when the level of the input signal becomes lower than a preset level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion compensation amplifier circuit, and more particularly to a distortion compensation amplifier circuit that does not perform erroneous distortion compensation optimization adjustment when the level of an input signal is decreasing.

[0002]

2. Description of the Related Art A conventional distortion compensating amplifier circuit includes a distortion extraction loop for extracting a distortion component mainly including intermodulation distortion generated in a main amplifier and a distortion suppression loop for removing the extracted distortion component. In order to compensate for the distortion component generated in the amplifier, the amount of attenuation and phase of the vector adjustment circuit provided in the distortion extraction loop is controlled by optimization using the input signal component or the pilot signal superimposed on the input signal. In addition, the control of optimization is performed by using a pilot signal superimposed before or after the main amplifier on the amount of attenuation and the amount of phase of the vector adjustment circuit provided in the distortion suppression loop.

In the conventional distortion compensation amplifier circuit, when the adjustment of the two vector adjustment circuits uses the corresponding pilot signals, the control can always be performed irrespective of the level of the input signal. The need for a pilot oscillator complicates the device configuration, and in order to simplify the device configuration, one pilot signal, that is, when adjusting the vector adjustment circuit of the distortion extraction loop by detecting an input signal component, It is not possible to judge the difference between when the level of the input signal is gradually decreasing and the decrease in the detection level by adjusting the attenuation and phase of the vector adjustment circuit. Problem.

[0004]

In the above-described conventional distortion compensation amplifier circuit, when the distortion is compensated by one pilot signal by simplifying the device configuration, an erroneous distortion occurs when the level of the input signal is reduced. It has the disadvantage that it performs an optimization adjustment of the compensation.

[0005] An object of the present invention is to eliminate such a conventional drawback, when the level of the input signal falls below a preset level, stop the optimization adjustment of the vector adjustment circuit of the distortion extraction loop and Another object of the present invention is to provide a distortion compensation amplifier circuit that does not perform erroneous distortion compensation by using control data stored when the level of an input signal is high.

[0006]

According to the present invention, there is provided a distortion compensation method comprising:
A distortion extraction loop that divides the input signal into two, one performs first vector adjustment and main amplification, and synthesizes the other after the first phase adjustment, and the main amplification signal is divided into two, and one is subjected to the second A distortion adjusting loop for outputting a phase-adjusted signal, synthesizing the other signal with the first phase-adjusted signal, and then performing second vector adjustment and auxiliary amplification to synthesize the second phase-adjusted signal. In the compensation amplifying circuit, when the level of the input signal falls below a preset level, at least the first vector adjustment of the distortion extraction loop is stopped.

In addition, the distortion compensation method of the present invention includes a distortion extraction loop that splits an input signal into two, one of which is subjected to first vector adjustment and main amplification, and the other is subjected to first phase adjustment, and then combined.
The main-amplified signal is split into two, one is output with a second phase adjustment, and the other is combined with the first phase-adjusted signal, and then the second vector adjustment and auxiliary amplification are performed. A distortion suppression loop that combines the phase-adjusted signal with the phase-adjusted signal, wherein when the level of the input signal is higher than a preset level, at least the first vector adjustment An adjustment state is stored, and when the level of the input signal is lower than the preset level, the adjustment state is fixed to the adjustment state stored at least when the first vector adjustment goes back to a separately set time. It is characterized by being done.

The distortion compensating amplifier circuit according to the present invention comprises a first divider for branching an input signal into two paths, a first vector adjusting circuit for vector-adjusting one of the branched signals, A first path consisting of a main amplifier that amplifies the signal, a second delay line that adjusts the phase after a pilot signal is injected, a first delay line that adjusts the phase of the other of the branched signals, A second vector adjustment circuit that performs vector adjustment of a signal obtained by combining the signal of the first path branched after the pilot signal is injected into the first delay line output, and an auxiliary amplifier that amplifies the signal. The second
, The input signal, the signal of the auxiliary amplifier output, the second delay line output of the first path, and the second
An output signal obtained by combining the output of the auxiliary amplifier with the output of the auxiliary amplifier is supplied, and respective control signals are supplied to the first vector adjustment circuit, the second vector adjustment circuit, and a pilot signal generator that outputs the pilot signal. And a control unit that performs the control.

The control section includes a first level detector for detecting a level of the input signal, a second level detector for detecting an output level of the auxiliary amplifier, and a level detector for detecting a level of the output signal. A / D for inputting the output of each level detector and converting it into a digital signal
A converter, a level comparator for comparing the output of the first level detector with a preset level, a clock oscillator for generating and outputting a clock signal, an output of the level comparator, and an output of the A / D converter And the first vector adjustment circuit and the second
An operation unit (CPU) for outputting control data for adjusting the vector adjustment circuit to an optimum value and controlling on / off of the pilot signal generator; and a control signal obtained by converting the output of the operation unit into analog data to the first unit.
And a D / A converter to be supplied to the vector adjustment circuit and the second vector adjustment circuit, and when the level of the input signal is higher than the preset level, at least the first vector And a memory for storing control data for adjusting the adjustment circuit to an optimum value.

Further, the control unit stops the control for adjusting at least the first vector adjustment circuit to an optimum value when the level of the input signal falls below the preset level. I have.

The control unit may further include control data for adjusting at least the first vector adjustment circuit to an optimum value at every predetermined time when the level of the input signal is higher than the preset level. When the level of the input signal is lower than the preset level, the control data stored at a point in time that goes back to a preset time is stored. It is characterized in that it is converted into a control signal and output until it becomes higher than the level.

Further, the control section performs control to turn on the pilot signal generator only when adjusting the second vector adjustment circuit.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the distortion compensation amplifier circuit of the present invention.

In this embodiment shown in FIG. 1, a distributor 1 for branching a high-frequency input signal into two paths, a vector adjustment circuit 2 for vector-adjusting one of the branched signals, and a main circuit for amplifying the signal. A first path comprising an amplifier 3 and a delay line 9 for adjusting the phase after the pilot signal is injected;
A delay line 5 for adjusting the phase of the other branched signal, a vector adjusting circuit 10 for adjusting a vector of a signal obtained by combining a signal of the first path branched after a pilot signal is injected into the output of the delay line 5; , An auxiliary amplifier 1 for amplifying this
1, the input signal, the auxiliary amplifier 11
An output signal obtained by combining the output signal and the output of the delay line 9 on the first path with the output of the auxiliary amplifier 11 on the second path is input, and the vector adjustment circuit 2, the vector adjustment circuit 10, and the pilot signal for outputting the pilot signal The control unit 13 supplies each control signal to the generator 4.

The control unit 13 includes a level detector 31 for detecting the level of the input signal, a level detector 32 for detecting the output level of the auxiliary amplifier 11, and a level detector for detecting the output level of the synthesizer 12. 33, an A / D converter 34 for digitally converting the output of each level detector,
A level comparator 35 for comparing the output of the level detector 31 with a preset level; a clock oscillator 38 for generating and outputting a clock signal; an output of the level comparator 35;
An operation unit (C) that receives the output of the converter 34 and the output of the clock oscillator 38, outputs control data for adjusting the vector adjustment circuit 2 and the vector adjustment circuit 10 to an optimum value, and controls on / off of the pilot signal generator 4.
PU) 36, a D / A converter 37 that supplies a control signal obtained by converting the output of the arithmetic unit to analog data to the vector adjustment circuit 2 and the vector adjustment circuit 10, and when the level of the input signal is higher than a preset level And a memory 39 for storing at least a control data for adjusting the vector adjustment circuit 2 to an optimum value every certain time.

With this configuration, the distortion compensation method of the present invention is performed by stopping at least the control of the vector adjustment circuit 2 of the distortion extraction loop when the level of the input signal falls below a preset level. .

When the level of the input signal is higher than a preset level, control data for controlling at least the vector adjustment circuit 2 of the distortion extraction loop is stored at predetermined time intervals, and the level of the input signal is set in advance. When the level falls below the set level, the control data is fixed to the control data stored at a point in time that goes back to a separately set time.

Next, the operation of the distortion compensation amplifier circuit according to the present embodiment will be described in detail with reference to FIG.

In FIG. 1, a distributor 1 converts an input high-frequency input signal into a first path on the main amplifier 3 side and a delay line 5.
Branch to the second path on the side.

The vector adjustment circuit 2 is composed of a variable attenuator and a variable phase shifter. The attenuation and the phase shift are adjusted by a control signal from the control unit 13.

The main amplifier 3 amplifies a high frequency input signal to a required amplitude and outputs the amplified signal. The main amplifier 3 is used with a reduced back-off of the amplifier in order to enhance power efficiency, so that intermodulation distortion occurs.

The pilot signal generator 4 is usually injected at the center of the operating frequency range in order to suppress a distortion component generated in the main amplifier 3 by a distortion suppression loop.

The delay line 5 shifts the phase of the signal on the second path branched by the distributor 1 and cancels the signal when combined with the signal on the first path branched from the output of the main amplifier 3. Frequency component, that is, the phase difference of the input signal is 18
It is set to be 0 degrees.

The divider 6, the attenuator 7, and the combiner 8 are set so that when the first path and the second path are combined, the amplitude of the frequency component to be canceled is the same at the time of combination. Is done.

The delay line 9 is inserted after the main amplifier 3 on the first path, and when combined with the output after the output of the auxiliary amplifier 11 on the second path, the frequency component to be canceled, that is, the phase difference of the pilot signal Is set to 180 degrees.

The vector adjustment circuit 10 is composed of a variable attenuator and a variable phase shifter, similarly to the vector adjustment circuit 2, and the amount of attenuation and the amount of phase shift are adjusted by a control signal from the control unit 13.

The auxiliary amplifier 11 amplifies the distortion component of the output of the main amplifier 3 obtained by combining the output of the main amplifier 3 on the first path and the output of the delay line 5 on the second path and the injected pilot signal. I do. Since the auxiliary amplifier 11 does not include an input signal component and handles a low input level, the generated distortion is extremely small.

The combiner 12 combines the signal on the first path and the signal on the second path, cancels the frequency components to be canceled, that is, the distortion and the pilot signal, and obtains an output signal having no distortion component. .

When the control unit 13 determines that the level of the input signal is higher than a preset level, first,
With the pilot signal generator 4 turned off, the optimization of the variable attenuator and the variable phase shifter of the vector adjustment circuit 2 is performed, and then the pilot signal generator 4 is turned on and the variable attenuator of the vector adjustment circuit 10 is turned on. And the variable phase shifters are sequentially adjusted. When it is determined that the level of the input signal is lower than the preset level, the optimization of the vector adjustment circuit 2 is not performed, the pilot signal generator 4 is turned on, and the variable attenuator of the vector adjustment circuit 10 is turned on. And the variable phase shifters are sequentially adjusted.

When it is determined that the level of the input signal is higher than the preset level, the control unit 13 controls the vector adjustment circuit 2 for each period obtained by dividing the clock signal output from the clock oscillator 38. The control data corresponding to the amount of attenuation and the amount of phase shift are stored in the memory 39, and when the level of the input signal becomes lower than a preset level, the control data is stored at a point in time which goes back to a separately set time. Converts control data to analog and adjusts vector 2
To supply.

Next, an optimization adjustment procedure according to the present embodiment will be described with reference to flowcharts. FIG. 2 is a flowchart illustrating an example of the optimization adjustment procedure according to the embodiment of this invention.

First, the level of the input signal is detected by the level detector 3.
1 and is determined by the level comparison circuit 35 (10
1). If the level of the input signal is equal to or higher than a preset level, the attenuation of the variable attenuator constituting the vector adjustment circuit 2 of the distortion extraction loop is optimized and adjusted (102).
Subsequently, optimization adjustment of the phase shift amount of the variable phase shifter is performed (10
3). In each optimization method, for example, when optimizing the amount of attenuation, the amount of attenuation of the variable attenuator is increased or decreased by a control signal, and adjusted so that the output of the level detector 32 is minimized. Also when optimizing the phase shift amount, the phase shift amount of the variable phase shifter is increased or decreased by a control signal, and the level detector 3
2 is adjusted so as to minimize the output. When the attenuation amount and the phase shift amount are combined and become the minimum level, the two input signal components to be canceled by the output of the combiner 8 are:
The phase becomes the same amplitude and the phase is reversed, and only the distortion component is extracted.

Next, the pilot signal generator 4 shown in FIG.
Is turned on (104), the optimization of the attenuation of the variable attenuator constituting the vector adjustment circuit 10 of the distortion suppression loop is performed (105), and then the optimization of the phase shift of the variable phase shifter is adjusted. Perform (106). Optimization adjustment methods for the attenuation amount and the phase shift amount of the distortion suppression loop can be performed in the same manner as the optimization adjustment method of the distortion extraction loop.

The level of the input signal is determined by the level comparing circuit 35 (101). If the level of the input signal is equal to or less than the preset level, the optimization of the vector adjustment circuit 2 of the distortion extraction loop is performed. Instead, the pilot signal generator 4 is turned on (104), and the optimization adjustment of the attenuation amount of the distortion suppression loop (105) and the optimization adjustment of the phase shift amount (106) are performed. When the adjustment of the vector adjustment circuit 10 of the distortion suppression loop is completed, the pilot signal generator 4 is turned off, the process returns to the first input level determination (101), and the operation is repeated thereafter.

Turning off the pilot signal eliminates the pilot signal injected near the center of the band of the input signal, minimizes the level of the dominant input signal, and extracts only the distortion component. This is a necessary procedure to perform optimization adjustment. Further, since this distortion component decreases significantly as the level of the input signal decreases, the necessity of the optimization adjustment is small when the level of the input signal is low. Further, when the level of the input signal is gradually decreasing, the detection of the level of the input signal is minimized and erroneous, and the input signal goes in a direction opposite to the original optimum value. This can prevent incorrect distortion adjustment.

In the above description, when the level of the input signal becomes equal to or lower than the preset level, the optimization adjustment of the vector adjustment circuit 2 of the distortion extraction loop is stopped, so that it is fixed to the immediately preceding control signal. However, the present invention is not limited to this, and may be arbitrary control data.

FIG. 3 is a flowchart showing another example of the optimization adjustment procedure according to the embodiment of the present invention.

According to FIG. 3, first, the level of the input signal is determined (201), and when the level of the input signal is equal to or higher than a preset level, optimization of the attenuation of the distortion extraction loop (202) is performed. Optimization of the amount of phase shift (203) is performed. The contents are the same as those in the case of the flow in FIG. 2, and the description is omitted here.

Next, the timer starts counting (20
4). This timer converts a clock signal output from the clock oscillator 38 shown in FIG.
6. The clock generated by dividing the frequency inside 6 is counted. The timer determines the elapsed time (205), and if a predetermined “a” second has elapsed, the control data corresponding to the attenuation amount and the phase shift amount of the vector adjustment circuit 2 of the distortion extraction loop at that time is stored in the memory. Remember in 39 (20
6), the count of the timer is cleared (207). The stored control data is stored up to n each time "a" seconds elapse, and is shifted by one each time it is stored. However, if the timer has not passed the preset "a" seconds, the control data is not stored and the timer continues counting. Subsequently, the data set flag "b" seconds before, which indicates the setting state of the control data to be supplied to the vector adjustment circuit 2 when the input signal decreases, is cleared to "0" (208). Next, the pilot signal generator 4 is turned on (209), and the optimization of the attenuation of the distortion suppression loop (210) and the optimization of the phase shift of the distortion suppression loop (21).
1) is performed. The adjustment method is the same as the flow in FIG. Then, the pilot signal generator 4 is turned off (21
2) Return to the input signal level determination (201).

Next, the level of the input signal was determined (20
1) As a result, if it is determined that the level of the input signal is lower than the preset level, the data set flag "b" seconds ago is checked (213). When the flag is "0", it indicates that the level was high until the previous time and the current level was low. In this case, the control data corresponding to the attenuation amount and the phase shift amount of the vector adjustment circuit 2 "b" seconds before is read out from the memory 39 without performing the optimization adjustment of the distortion extraction loop and set (214). A control signal obtained by converting the control data into an analog signal is supplied to the vector adjustment circuit 2. Then, the data set flag before “b” seconds is set to “
1 (215) If the flag is "1", it indicates that the level of the input signal is continuously low, and the attenuation amount of the distortion extraction loop "b" seconds ago at the previous time. Since the phase shift amount data has been set, the pilot signal generator 4 is turned on (209), and the process proceeds to the adjustment of the distortion suppression loop, and when the adjustment of the distortion suppression loop is completed, the process returns to the input level determination (201). Thereafter, this operation is repeated.

Here, the time “b” seconds is the time “a” seconds when the input signal level is updated immediately before the level becomes lower than the preset level, and the time when the input signal level is continuously stored. Values up to a time of “n × a” seconds can be taken up to the maximum number “n”. When data before "b" seconds does not exist, for example, immediately after the power is turned on, data at a time closest to "b" seconds is used.

As the control data, an average of "n" pieces of control data or an average up to the previous time can be taken at any time.

In the above embodiment, only the control of the distortion extraction loop is stopped and the control of the distortion suppression loop is always performed. However, in general, when the level of the input signal is low, the occurrence of intermodulation distortion occurs. And the amount of heat generated by the main amplifier 3 itself is small, so that it is not necessary to optimize the amount of distortion. Therefore, the optimization adjustment of the distortion suppression loop can be stopped in the same manner as the distortion extraction loop. . As described above, by performing optimization control only when the input signal level is high, the amount of data to be handled can be reduced, and the apparatus configuration can be simplified, such as by using only one pilot signal. be able to.

Note that the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention.

[0045]

As described above, according to the distortion compensation method and the distortion compensation amplifier circuit of the present invention, when the level of the input signal is decreasing, the optimization adjustment of the vector adjustment circuit of the distortion extraction loop is stopped. By doing so, there is an effect that erroneous distortion compensation can be prevented.

When the level of the input signal is higher than the preset level, at least at every certain time, the adjustment state of the vector adjustment circuit of the distortion extraction loop is stored, and the level of the input signal is set to the preset level. When the data is further reduced, by fixing the control data of the vector adjustment circuit of the distortion extraction loop to the control data stored at a point in time that is set back to a separately set time, the amount of data to be handled can be reduced. This has the effect of simplifying the device configuration, such as by using only one pilot signal, and realizing a distortion compensation amplifier circuit that does not perform erroneous distortion compensation.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an example of an optimization adjustment procedure according to the embodiment of the present invention.

FIG. 3 is a flowchart showing another example of the optimization adjustment procedure according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Divider 2 Vector adjustment circuit 3 Main amplifier 4 Pilot signal generator 5 Delay line 6 Distributor 7 Attenuator 8 Synthesizer 9 Delay line 10 Vector adjustment circuit 11 Auxiliary amplifier 12 Synthesizer 13 Control part 31 Level detector 32 Level detection Device 33 level detector 34 A / D converter 35 level comparator 36 arithmetic unit (CPU) 37 D / A converter 38 clock oscillator 39 memory

Claims (7)

[Claims] 1. A distortion extraction loop for splitting an input signal into two parts, one of which is subjected to a first vector adjustment and main amplification, and the other of which is subjected to a first phase adjustment, and a main part of the main amplified signal is split into two parts. Distortion suppression in which one is output with a second phase adjustment, the other is synthesized with the first phase-adjusted signal, and then the second vector adjustment and auxiliary amplification are performed to synthesize the second phase-adjusted signal. A distortion compensation amplifier circuit comprising a loop, wherein when the level of the input signal falls below a predetermined level, at least the first vector adjustment of the distortion extraction loop is stopped. Method. 2. A distortion extraction loop for splitting an input signal into two parts, one of which is subjected to a first vector adjustment and main amplification, and the other of which is subjected to a first phase adjustment, and a main extraction signal, which is split into two parts, Distortion suppression in which one is output with a second phase adjustment, the other is synthesized with the first phase-adjusted signal, and then the second vector adjustment and auxiliary amplification are performed to synthesize the second phase-adjusted signal. A distortion compensation amplifier circuit comprising a loop, when the level of the input signal is higher than a preset level, storing at least an adjustment state of the first vector adjustment at a certain time interval; Is lower than the preset level, at least the first vector adjustment is fixed to an adjustment state stored at a point in time that goes back to a separately set time. Atonement method. 3. A first divider for branching an input signal into two paths, a first vector adjustment circuit for vector-adjusting one of the branched signals, a main amplifier for amplifying the signal, and a pilot signal Phase adjustment after the second is injected
A first path including a delay line, a first delay line that adjusts the phase of the other signal that has been branched, and the first path that is branched after the pilot signal is injected into the output of the first delay line. A second path including a second vector adjustment circuit that performs vector adjustment of a signal obtained by combining the signal of the first path and an auxiliary amplifier that amplifies the signal, the input signal, the signal of the auxiliary amplifier output, and the An output signal obtained by combining the output of the second delay line on the first path and the output of the auxiliary amplifier on the second path is input, and the first vector adjustment circuit, the second vector adjustment circuit, A distortion compensation amplifier circuit, comprising: a control unit that supplies each control signal to a pilot signal generator that outputs a pilot signal. 4. The control section includes a first level detector for detecting a level of the input signal, a second level detector for detecting an output level of the auxiliary amplifier, and detecting a level of the output signal. A third level detector, an A / D converter for inputting and digitally converting the output of each level detector, a level comparator for comparing the output of the first level detector with a preset level, A clock generator for generating and outputting a clock signal, and receiving the level comparator output, the A / D converter output, and the clock oscillator output, and setting the first vector adjustment circuit and the second vector adjustment circuit to optimal values An arithmetic unit (CPU) for outputting control data to be adjusted to and for controlling the pilot signal generator to be on / off; and converting the arithmetic unit output to analog data. A D / A converter for supplying the converted control signal to the first vector adjustment circuit and the second vector adjustment circuit; and a method for setting the input signal level higher than the preset level for a certain period of time. 4. The distortion compensation amplifier circuit according to claim 3, further comprising: a memory for storing control data for adjusting at least the first vector adjustment circuit to an optimum value for each time. 5. The control unit according to claim 1, wherein when the level of the input signal is lower than the preset level, at least the control for adjusting the first vector adjustment circuit to an optimum value is stopped. The distortion compensation amplifier circuit according to claim 3 or 4, wherein: 6. The control unit, when the level of the input signal is higher than the preset level, generates control data for adjusting at least the first vector adjustment circuit to an optimal value at every certain time. When the level of the input signal is lower than the preset level, the control data stored at a point in time that goes back to a preset time is stored. 5. The distortion compensation amplifier circuit according to claim 3, wherein the signal is converted into a control signal and output until the level becomes higher than the level. 7. The control unit according to claim 3, wherein said control unit performs control to turn on said pilot signal generator only when adjusting said second vector adjustment circuit.
Or the distortion compensation amplifier circuit according to 6.