JP2000307354A - Distortion compensation power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the variation of a main signal component and to stably reduce distortion by generating distortion by connecting a wide band small power amplifier to the first output of a third power distributor for distributing power to three systems, providing only a distortion signal by subtracting distortion from a second output and removing the main signal component, and supplying the distortion signal, in which the main signal component and a main signal are not included, to a main amplifier by adding the distortion signal with a third output. SOLUTION: The distortion signal, from which the main signal component is removed, is added with an input signal by a second power synthesizer 30. The distortion signal is of the power level of one to the component of a gain to the distortion signal generated by a main amplifier 13 connected to the output of the second power synthesizer 30, and the amplitude and the phase are controlled by a second vector controller 51 so as to provide opposite phases. Besides, since the main amplifier 13 is in a linear operating area in respect to the level of the distortion signal injected to the input of the main amplifier 13, the distortion of the main amplifier 13 becomes an extremely small value in respect to the injected distortion signal and the distortion signal to be generated by the main amplifier 13 is generated only by the main signal component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a low distortion power amplifier,
In particular, the present invention relates to a distortion compensation type power amplifier suitable for a high frequency power amplifier for a wireless communication device.

[0002]

2. Description of the Related Art As a conventional technology regarding a power amplifier,
For example, JP-A-8-265052 can be mentioned. Hereinafter, the prior art will be described with reference to FIG.

A directional coupler 2 for extracting a part of an input signal
06 and a first hybrid 201 provided at the output of the directional coupler 206 for dividing power into the first and second outputs.
A distortion generating circuit 202 connected to a first output of the first hybrid and configured by a non-linear element such as a diode or a GaAs FET to generate a third-order distortion;
, A variable phase circuit 151 connected to the second output of the first hybrid 201 to adjust the phase amount, and an output of the variable phase circuit 151 having the output of the attenuation circuit 150 as a first input. A second hybrid 30 that takes an output as a second input and combines the first and second inputs into two,
A main power amplifier 13 having an output of the second hybrid 30 as an input, a detection circuit 207 for detecting a signal obtained by extracting a part of the input signal from the directional coupler 206, and a detection circuit 20
7, a distortion generation bias control circuit 208 that changes the bias of the variable attenuator 150 that changes the degree of attenuation of the output of the distortion generation circuit 202, and a phase that changes the bias of the variable phase circuit 151 based on the output of the detection circuit 207. This is a configuration including a bias control circuit 209.

After passing through a directional coupler 206, an input signal from an input 11 is divided into two by a first hybrid 201 into a first output and a second output. The first output is input to a distortion generation circuit 202 where a third-order distortion is generated and an attenuator 1
50 adjusts the amplitude. The second output of the first hybrid 201 is the first output of the first hybrid 201.
Is adjusted by the phase bias control circuit 209 so as to suppress the phase fluctuation with respect to the signal from the output of the second hybrid 30 to the second hybrid 30. Further, the distortion generation amount of the distortion generation circuit is controlled by the distortion generation bias control circuit 208 according to the input signal level. As described above, since the amount of distortion and the phase variation are controlled by the input signal level, distortion compensation of the main amplifier can be stably performed with respect to the variation of the input level.

[0005]

The above-described distortion generating circuit generates distortion by utilizing the non-linearity of a diode or a transistor. At this time, the signal component appearing at the output is both the main signal component of the input and the distortion component generated due to the non-linearity. When synthesizing this output and a signal which has passed through the variable phase shifter and has not been subjected to distortion, there is some phase difference with respect to the main signal component. This phase difference is a phase difference that removes distortion of the main amplifier in the conventional example.
It can be said that there is no correlation between the first main signal component that has passed through the distortion generator and the second main signal component that has passed through the variable phase shifter. Therefore, when adjusting the variable phase shifter to suppress the phase fluctuation of the distortion, the phase relationship between the first main signal and the second main signal fluctuates from the same phase to the opposite phase. Therefore, the main signal component supplied to the main amplifier becomes a signal level added or subtracted from the originally input signal level due to phase fluctuation, and the signal level obtained by adding or subtracting the main signal component is not stable. Furthermore, since the amount of distortion generated by the main amplifier fluctuates due to the fluctuation of the main signal component, the amount of distortion and the phase of the distortion generating circuit must always be adjusted, which is not stable for distortion removal.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems of the prior art, and has as its object to provide an amplifier that suppresses fluctuations of a main signal component and stably reduces distortion. I do.

[0007]

An input signal is divided into three by a first power divider for distributing input power to three systems, and a wideband small power amplifier is connected to a first output of the first power divider, thereby distorting the input signal. Is generated, and subtracted from the second output of the power divider to remove the main signal component to obtain only the distortion signal, and added to the third output of the first power divider to add the main signal component and the main signal. A distortion signal that is not included is supplied to the main amplifier.

At this time, the distortion generated by the main amplifier can be reduced by adjusting the amplitude and phase of the distortion signal before being added to the third output of the power divider. According to the present invention, the main signal component can be stably supplied to the main amplifier, and the distortion can be stably compensated by a distortion signal not depending on the main signal.

[0009]

FIG. 1 is a block diagram showing an embodiment of the present invention. The first, second, and third 3 are input to the signal input 11.
A first power distributor 15 for distribution to the grid is connected. A first output of the first power divider 15 is connected to a distortion generating amplifier 41 composed of a wideband small signal amplifier that reaches a saturation power by an input signal and generates a distortion signal. Between the output of the amplifier and the distortion generating amplifier.
In order to adjust the amount of distortion generation, a distortion generation adjuster 40 for adjusting the amplitude level of the input signal of the generation amplifier 41 is inserted. The output of the distortion generating amplifier 41 is connected to a first vector adjuster 50 for adjusting power amplitude and phase, and is connected to a first input of the first power combiner 31. A second output of the first power divider 15 is a first delay line 20 having a delay time of a path from a first output of the second power divider 15 to a first input of the first power combiner 31. Connected to. An output of the first delay line 20 is connected to a second input of the first power combiner 31. The first vector adjuster 50 is connected to the first power combiner 31.
The main signal components are reduced by adjusting the respective inputs to have the same amplitude and opposite phase, and the distortion signal generated by the distortion generating amplifier 41 can be extracted from the output of the first power combiner 31.

The output of the first power combiner 31 is connected to a second vector adjuster 51 and to a first input of the second power combiner 30. The third output of the first power divider 15 is provided from the first output of the first power divider 15 to the second power combiner 30.
A second delay line 21 having a delay time of a path leading to a first input of the second power combiner 30 or a path leading from a second output of the first power divider 15 to a second input of the second power combiner 30 is connected. 2
Connected to a second input of power combiner 30. A main amplifier 13 for amplifying an input signal to a predetermined power level is connected to an output of the second power combiner 30.

FIG. 8 is a schematic diagram illustrating a change in spectrum at each element of the present invention. The operation will be described below with reference to FIGS. The distortion generating amplifier 41, which is a wideband small signal amplifier receiving the input signal, obtains an output near the saturation power. At this time, a distortion signal generated by the non-linearity of the distortion generation amplifier 41 and the main signal component which is an input signal is obtained at the output. The power level of the distortion signal and the ratio of third-order distortion, fifth-order distortion, and the like can be varied by a distortion generation adjuster 40 including a variable attenuator. The output of the distortion generating amplifier 41 is subtracted from the input signal by the first power combiner 31. At this time, the first power distributor 1
5 from the first output of the first power combiner 31 to the first input of the first power combiner 31 and the path from the second output of the first power divider 15 to the second input of the first power combiner 31. The amplitude is adjusted so that the amplitude is the same and the phase is the opposite phase. As a result, the main signal component can be removed from the signal obtained by the distortion generating amplifier 41 at the output of the first power combiner 31.
That is, only the distortion signal component can be extracted. Here, the vector adjuster is a variable attenuator 150 as shown in FIG.
And the variable phase shifter 151. The distortion signal from which the main signal component has been removed is added by the second power combiner 30 to the input signal. At this time, the second vector adjuster is configured such that the distortion signal has a power level of 1 / gain with respect to the distortion signal generated by the main amplifier 13 connected to the output of the second power combiner 30 and has an opposite phase. 51 adjusts the amplitude and phase. Thereby, distortion of the main amplifier can be easily compensated. Further, since the main amplifier is in a linear operation region with respect to the level of the distortion signal injected into the input of the main amplifier 13, the distortion of the main amplifier with respect to the injected distortion signal has an extremely small value, and the distortion signal generated by the main amplifier 13 is Occurs only by components. The distortion generation amount of the main amplifier 13 is stable without changing the amplitude and phase relationship of the second vector adjuster. Therefore, it is possible to provide a distortion-compensated power amplifier that suppresses the fluctuation of the main signal component and stably reduces the distortion. .

FIG. 2 is a block diagram of another embodiment of the present invention. In FIG. 1, a first directional coupler 60 for extracting a part of a signal is arranged on a path from the second power combiner 30 to the second vector adjuster 51. A first detector 61 for detecting the power of the combined output of the first directional coupler 60, a first analog-to-digital converter 62 for converting the detected output of the first detector 61 into a digital signal, and a converted digital signal A first control unit 63 that performs numerical operation and control for adjusting the first vector adjuster 50 based on
And a first digital-to-analog converter 64 for converting a control signal, which is a digital signal output from the controller, into an analog signal.

The first controller 63 controls the first detector 61 so that the detection output of the first detector 61 is minimized, that is, the main signal component is removed.
The first vector adjuster 50 adjusts the amplitude and phase of the calculation result of the first control unit 63 by voltage control. As a result, the main signal component can be removed from the signal generated by the distortion generating amplifier 41 by automatic control. Therefore, it is possible to suppress deterioration of the accuracy of removing the main signal due to changes in temperature and aging, to provide a distortion-compensated power amplifier that suppresses power fluctuation of the main signal component and stably reduces distortion.

FIG. 3 is a block diagram of another embodiment of the present invention. In FIG. 2, a second directional coupler 70 for extracting a part of the signal is disposed at a stage subsequent to the main amplifier 13. A first frequency conversion means 71 for converting the frequency of the output signal is connected to the combined output of the second directional coupler 70. The frequency is determined by the first frequency synthesizer 72 so that the first frequency conversion means 71 selects a desired frequency band.
The signal passes through a first band-pass filter 73 for extracting only a signal in a desired frequency band from the frequency-converted signal, and is converted into a voltage by a second detector 74 that detects power in a selected frequency band. The detection output of the second detector 74 is converted into a digital signal by a second analog-to-digital converter 75 that converts the detection output into a digital signal, and based on this, a numerical operation and control for adjusting the second vector adjuster 51 are performed. 2 input to the control unit 76. The calculation result is output from the second control unit 76 as a control signal. The control signal, which is a digital signal, is converted into an analog signal by the second digital-to-analog converter 77.

The first frequency synthesizer 72 operates within the system frequency band of the radio equipment, and operates so that each center frequency of the system frequency becomes the center of the pass band of the first band-pass filter 73.

A signal in each of the selected modulation bandwidths in the system frequency band passing through the first band-pass filter 73 is detected by a second detector 74, and the second detector 74
The second control unit 76 determines that the detected signal is the main signal component when the detection value is the maximum value in the detection output, and determines that the signal detected in the other frequency band is the distortion signal component. The judgment is made at 76. At this time, a numerical operation is performed by the second control unit 76 so that the total value of the detection values in the frequency band in which the distortion signal exists is minimized, and the amplitude and phase are adjusted by the second vector adjuster 51 by voltage control, and are automatically adjusted. Reduces the amount of distortion of the main amplifier. For this reason, it is possible to suppress the deterioration of the distortion signal removal accuracy due to changes in temperature and aging, and it is possible to provide a distortion-compensated power amplifier that suppresses power fluctuation of the main signal component and stably reduces distortion.

FIG. 4 shows another embodiment of the present invention.
A second power splitter 88 for splitting an input signal into two, a first system and a second system, is provided with respect to FIG. 3, and a first output of the second power splitter 88 is connected to the first power splitter 15. Input and second
The second output of the power divider 88 passes through a third vector adjuster 87 for adjusting the power amplitude and phase, and is connected to a third power combiner 82. A first fixed attenuator 81 and a third power combiner 82 provided on a path from the combined output of the second directional coupler 70 to the first frequency converter 71 are inserted. The third power combiner 82 adds the second output of the second power divider 88 and the combined output of the second directional coupler 70. Third
The output of the power combiner 82 is used as the input of the first frequency converter 71, and the output of the third power combiner 82 is detected by a third detector 83 that is separately connected to the output of the third power combiner 82. The detection output of the third detector 83 is converted into a digital signal by a third analog-to-digital converter 84 which converts the output into a digital signal.

Based on this, it is input to a third control unit 85 which performs numerical operation and control for adjusting the third vector adjuster 87. The calculation result is output from the third control unit 85 as a control signal. The control signal, which is a digital signal, is converted into an analog signal by a third digital-to-analog converter 86.

A signal obtained by partially extracting the output signal of the main amplifier 13 by the second directional coupler 70 and an input signal are added to a third power combiner 82 so that the detection output of the third detector 83 is minimized. The third control unit 85 performs a numerical operation so as to be as follows.
The operation result of the third control unit 85 is adjusted by voltage control to adjust the amplitude and phase by a third vector adjuster. At this time the third
The detection value of the detector 83 is minimized by the third power combiner 8.
2 when the amplitudes of the respective inputs are equal and the phases are opposite to each other, and the third power combiner 82
The output is only the residual distortion signal component included in the output of the main amplifier 13.

The frequency of the output of the third power combiner 82 is changed, detected and operated, and the second vector adjuster 51 is adjusted.
In a system in which the distortion of the main amplifier 13 is minimized, the detection of the residual distortion component becomes easy because the main signal component is removed even when the distortion is reduced. Thereby, the detection accuracy of residual distortion is further improved, and a distortion-compensated power amplifier that stably reduces distortion can be provided.

FIG. 5 is a block diagram of another embodiment of the present invention. 4, a linear amplifier 90 is provided on a path from the output of the first power combiner 31 to the input of the second power combiner 51. By increasing the power level of the distortion signal by the linear amplifier 90, the distortion amount of the main amplifier 13 can be automatically reduced even when the distortion signal of the main amplifier is large,
Provided is a distortion compensation power amplifier that automatically suppresses fluctuation of a main signal component and stably reduces distortion.

FIG. 6 shows another embodiment of the present invention.
From the input signal 11 of the distortion compensating amplifier of FIG. 5 via the first output of the second power divider 88, the output of the main amplifier 13 and the second
A path connecting the input of the directional coupler 70, a path connecting the second output of the second power divider 88 and the input of the third vector adjuster 87, a control input of the second vector adjuster 51 and a second
The path connecting the output of the digital-to-analog converter 77 is disconnected, and all elements on the path from the input signal 11 to the output of the main amplifier 13 via the first output of the second power divider 88 and the second power The first directional coupler 66 is connected via a first output of the divider 88 and the second power divider 88 of the embodiment of FIG.
And all elements from the control input of the first vector adjuster 50 to the second input of the first directional coupler 66 are deleted, and the signal input 101 is changed to the first and second signals. , A third power distributor 10 for distributing signals to the third three systems
Place 3. First, the first output of the third power divider 103 is connected to the fifth vector adjuster 104. The output of the fifth vector adjuster 104 is connected to the distortion compensation power amplifier 200 shown in FIG. Distortion compensation power amplifier 200
A third directional coupler 105 for extracting a part of the output signal power is disposed at the output of the third directional coupler 105. The combined output of the third directional coupler 105 is connected to a second fixed attenuator 109 for attenuating the output signal of the distortion compensation power amplifier. Connected. The addition of the two systems is performed by a fourth power combiner 111 using the output of the second fixed attenuator 109 as a first input and the second output of the third power divider 103 as a second input.

On the path from the second output of the third power divider 103 to the second input of the fourth power combiner 111, a third
From the first output of the power divider 103 to the fourth power combiner 10
The third delay line 110 having the delay time of the path leading to the first input of No. 9 is inserted. A fourth directional coupler 112 that extracts a part of the output of the fourth power combiner 111 is connected to the output of the fourth power combiner 111. Fourth directional coupler 112
Is connected to an error amplifier 114 via a fourth vector adjuster 113 for adjusting the power amplitude and phase. The third directional coupler 10 uses the output of the error amplifier 114 as a coupling input.
A fifth directional coupler 107 having the output of No. 5 as a first input is arranged. On the path from the output of the third directional coupler 105 to the first input of the fifth directional coupler 107, from the combined output of the third directional coupler 105 to the combined input of the fifth directional coupler 107 Fourth delay line 10 having path delay time
Insert 6.

A fourth detector 120 is connected to the combined output of the fourth directional coupler 112, passes through a fourth analog-to-digital converter 121 that converts the detected output into a digital signal, and outputs the converted digital signal. Is input to a fourth control unit 122 that performs numerical calculation and control for adjusting the fifth vector adjuster 104. The calculation result is output from the fourth control unit 122 as a control signal. The control signal, which is a digital signal, is converted into an analog signal by a fourth digital-to-analog converter 123.

The output of the fifth directional coupler 107 and the disconnected input of the second directional coupler 70 are connected. The third output of the third power divider 103 is connected to the input of the disconnected third vector adjuster 87. The output of the second digital-to-analog converter 77 and the fourth vector adjuster 113 are connected.
The output of the fifth digital-to-analog converter 140 and the second vector adjuster 51 in the distortion compensation power amplifier 200 are connected. The output of the sixth digital-to-analog converter 141 and the distortion compensation power amplifier 200 in the distortion compensation power amplifier 200 are connected to the distortion compensation power amplifier included in the feed forward. Hereinafter, the flow of distortion removal will be described.

The output signal of the main amplifier 13 is added to the combined output of the second directional coupler 70 and the third output of the third power divider by a third power combiner 82, and the output of the third power combiner 82 is added. The output is detected by a third detector 83, and a numerical operation is performed by a third controller 85 so as to minimize the detected value, as in the other embodiments. The third vector adjuster 87 adjusts the amplitude and phase according to the voltage obtained by the operation of the third control unit 85. At this time, the detection value of the third detector 83 is minimized by the third power combiner 82
In this case, the amplitudes of the respective inputs are equal and the phases are opposite to each other, and only the residual distortion signal component included in the output of the main amplifier 13 is included in the output of the third power combiner 82 by a series of operations.

Next, the output of the third power combiner 82 is frequency-converted by the first frequency converter, detected by the second detector 74, and calculated by the second controller 76. The fourth vector adjuster 113 is passed through the second digital-to-analog converter 77 based on the operation result.
Via the fifth digital-to-analog converter 140 to adjust the amplitude and phase of the second vector adjuster 51. Similarly, the distortion generator 40 is adjusted via the sixth digital-to-analog converter 141 to minimize the distortion of the main amplifier 13.

The second detector 74 of the system for adjusting the second vector adjuster 51, the fourth vector adjuster 113, and the distortion generation adjuster 40 removes the main signal component even when the distortion of the main amplifier is reduced. Therefore, it is easy to detect the residual distortion component. Further, the detection accuracy of the residual distortion is further improved. This makes it possible to provide a distortion-compensating power amplifier that automatically suppresses fluctuations in the main signal component and stably reduces distortion.

[0029]

According to the present invention, since the distortion signal independent of the main signal is superposed on the main signal, the main signal is stably supplied to the main amplifier and the distortion compensation power for stably reducing the distortion signal. The accuracy of distortion removal can be improved by the amplifier.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

FIG. 3 is a block diagram of another embodiment of the present invention.

FIG. 4 is a block diagram of another embodiment of the present invention.

FIG. 5 is a block diagram of another embodiment of the present invention.

FIG. 6 is a block diagram of another embodiment of the present invention.

FIG. 7 is a configuration of a vector adjuster used in the distortion compensation power amplifier of the present invention.

FIG. 8 is an explanatory diagram of distortion removal of the distortion compensation power amplifier of the present invention.

FIG. 9 is a block diagram of a conventional distortion-compensated power amplifier.

[Explanation of symbols]

 11 signal input, 12 signal output, 13 main amplifier, 15 first power divider, 20 first delay line, 21 second delay line, 30 second power combining , 31 電力 first power combiner, 40 発 生 distortion generator, 41 発 生 distortion amplifier, 50 ‥‥ first vector regulator, 51 ‥‥ second vector regulator, 60 ‥‥ first direction 61} first detector, 62} first analog-to-digital converter, 63} first controller, 64} first digital-to-analog converter, 70} second directional coupler, 71 ‥‥ first frequency converter, 72 ‥‥ first frequency synthesizer, 73 ‥‥ first bandpass filter, 74 ‥‥ second detector, 75 ‥‥ second analog-to-digital converter, 76 ‥‥ second control Part, 77 ‥‥ second digital-analog converter, 81 、 {First fixed attenuator, 82} Third power combiner, 83} Third detector, 84} Third analog-to-digital converter, 85} Third control unit, 86} Third digital-to-analog conversion 87 # third vector adjuster, 88 # second power divider, 90 # linear amplifier, 101 # feedforward distortion compensation input, 102 # feedforward distortion compensation output, 103 # th 3 power splitter 104 104 fifth vector adjuster 105 105 third directional coupler 106 106 fourth delay line 107 107 fifth directional coupler 109 109 second fixed attenuator , 110３third delay line, 111 合成 4th power combiner, 112 ‥‥ 4th directional coupler, 113 ‥‥ 4th vector adjuster, 114４error amplifier, 120 ‥‥ 4th detector , 121 ‥‥ 4th analog Digital converter, 122 {fourth control unit, 123} fourth digital-analog converter, 140 fifth digital-analog converter, 141 {sixth digital-analog converter, 150} variable attenuator, 151 {Variable phase shifter, 200} Distortion compensation power amplifier, 201 {First hybrid, 202} Distortion generating circuit, 150} Attenuator, 30 {Second hybrid, 151} Variable phase shifter, 206} {Directional coupler, 207} detection circuit, 208} distortion generation bias control circuit, 209} phase bias control circuit.

Continued on the front page F term (reference) 5J090 AA01 AA41 CA21 FA08 GN02 GN04 GN07 HA19 HA24 KA00 KA12 KA15 KA16 KA23 KA34 KA41 KA44 KA55 KA68 MA14 SA13 TA01 TA02 5J091 AA01 AA41 CA21 FA08 HA19 KA14 KA00 KA00 KA00 MA14 SA13 TA01 TA02

Claims (7)

[Claims] 1. A first power divider for distributing input power to first, second and third outputs, a distortion generator for generating a distortion signal from the signal of the first output, and the distortion generator A first vector adjuster for adjusting the phase of the output of the first vector adjuster, a first power combiner for combining the output of the first vector adjuster and the second output, and a phase of the output of the first power combiner. A second vector adjuster that adjusts, a second power combiner that combines the output of the second vector adjuster and the third output, and a main amplifier that receives the output of the second power combiner as an input. A distortion-compensating power amplifier, comprising: 2. The first vector adjuster according to claim 1, wherein the first vector adjuster adjusts a main signal component of the first output to have an opposite phase to the second output. A distortion-compensated power amplifier, wherein the third output is adjusted so that a distortion signal component of an output of the second power combiner has an opposite phase to a distortion signal generated by the main amplifier. 3. The distortion according to claim 1, further comprising a first control unit that detects an output of the first power combiner and controls an adjustment amount of the first vector adjuster. Compensated power amplifier. 4. A first band-pass filter for extracting a distortion signal component from a signal subsequent to a main amplifier according to claim 1, and the second vector adjuster based on an output of the first band-pass filter. And a second control unit for controlling the adjustment amount of the distortion compensation power amplifier. 5. Distributing input power to first, second, and third outputs, generating a signal including a distortion signal from the signal of the first output, and using the second output to generate the distortion signal. A distortion signal component that appears when the third output is amplified by the main amplifier using the signal having the reduced main signal component. Compensation method. 6. A distortion compensating method according to claim 5, wherein a phase difference between said second output and a signal containing said distortion signal is adjusted using said signal having said main signal component reduced. . 7. A signal according to claim 5, wherein a distortion signal component is extracted from a signal at a subsequent stage of said main amplifier, and said third output and said main signal component are reduced based on the extracted distortion signal component. A distortion compensation method characterized by adjusting a phase difference between the first and second distortions.