JP2002171136A - Low-distortion power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the circuit scale of a pre-distortion compensator circuit is large. SOLUTION: A distributor circuit 103 distributes carrier frequencies to a linear amplifier 104 and a nonlinear amplifier 105. The distortion characteristics (the amplitude and the phase of a distortion to a carrier) of the nonlinear amplifier 105 are the same as those of a power amplifier 107. They are so adjusted that the output ratio of the linear amplifier 104 to the nonlinear amplifier 105 is 4:1, and these signals are combined in opposite phase to generate a distortion having the same amplitude in opposite phase as that of a distortion generated in the power amplifier 107.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low distortion power amplifier used for a portable telephone terminal and a base station.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional low distortion power amplifier.

In FIG. 8, a signal input from an input terminal 801 is distributed by a distribution circuit 803 to two paths.
One is a power amplifier 80 via a vector adjustment circuit 804.
The signal is amplified linearly at 5 and input to the synthesis circuit 811. The other output from the distribution circuit 803 is input to the distribution circuit 806. One of the outputs of the distribution circuit 806 is linearly amplified by the power amplifier 808 via the vector adjustment circuit 807, and is input to the synthesis circuit 810. The distribution circuit 806
The other output from is input to power amplifier 809,
A signal including distortion is generated and input to the synthesis circuit 810.

Here, by adjusting the vector adjustment circuit 807 so that the signal components of the carrier wave have the same amplitude and opposite phase in the combining circuit 810, the output from the combining circuit 810 is only a distortion component. This distortion signal is input to the synthesis circuit 811.

The synthesizing circuit 811 includes a vector adjusting circuit 8
By adjusting 04, the distortion output from the synthesis circuit 811 is set to have the same amplitude and the opposite phase as the distortion generated in the power amplifier 812. By inputting a signal including such distortion to the power amplifier 812, distortion generated in the power amplifier 812 can be suppressed.

[0006]

However, although the circuit of FIG. 8 can amplify power with low distortion,
The circuit scale becomes large.

That is, the conventional low distortion power amplifier has a problem that the circuit scale is large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low distortion power amplifier which does not increase the circuit scale in consideration of the above problems.

[0009]

A first aspect of the present invention (corresponding to claim 1) is a distribution circuit for distributing an input signal into two,
A first power amplifier connected to one of the output terminals of the distribution circuit for linearly amplifying the input signal; and a first power amplifier connected to the other output terminal of the distribution circuit for generating distortion of the input signal. A second power amplifier, a combining circuit for combining and outputting the output of the first power amplifier and the output of the second power amplifier, and a third power amplifier connected to the output of the combining circuit The distortion characteristics of the second power amplifier and the distortion characteristics of the third power amplifier are substantially the same, the output power of the first power amplifier and the output power of the second power amplifier And that the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier are combined with a phase difference of 180 degrees. Low distortion power amplifier .

Further, the second invention (corresponding to claim 2)
Is connected to the output of the second power amplifier, a first modulation frequency trap circuit whose impedance at a modulation frequency of a modulation wave of the input signal is smaller than a predetermined value, and connected to an output of the third power amplifier. And a second modulation frequency trap circuit having an impedance at a modulation frequency of a modulation wave of the input signal smaller than a predetermined value. The low distortion power amplifier according to the first aspect of the present invention.

Further, a third aspect of the present invention (corresponding to claim 3)
Is connected to an output of the second power amplifier, a first harmonic trap circuit having an impedance at a second harmonic of the input signal smaller than a predetermined value, and connected to an output of the third power amplifier. A second harmonic trap circuit having an impedance at a second harmonic of the input signal smaller than a predetermined value. The low distortion power amplifier according to the first aspect of the present invention.

Further, the fourth invention (corresponding to claim 4)
A distribution circuit for dividing the input signal into two, a first vector adjustment circuit connected to one of the output terminals of the distribution circuit for adjusting the amplitude and phase of the input signal, and the first vector adjustment A first power amplifier connected to an output of the circuit for linearly amplifying the adjusted signal; and a first power amplifier connected to the other output terminal of the distribution circuit for adjusting the amplitude and phase of the input signal. A second vector adjustment circuit, a second power amplifier connected to an output of the second vector adjustment circuit for generating distortion of the adjusted signal, and an output of the first power amplifier; A combining circuit for combining and outputting the output of the second power amplifier, and a third power amplifier connected to the output of the combining circuit, wherein the distortion characteristic of the second power amplifier and the third Power amplifier distortion The characteristics are substantially the same, and the combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4 to 1, and is output from the first power amplifier. A low distortion power amplifier characterized by combining a carrier signal and a carrier signal output from the second power amplifier with a phase difference of 180 degrees.

Further, the fifth invention (corresponding to claim 5)
Comprises an output level detection circuit connected to the output of the third power amplifier, for detecting the output level of the third power amplifier, and a control circuit connected to the output of the output level detection circuit, The control circuit controls an adjustment amount of an amplitude and a phase adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit according to the detected output level. Is a low distortion power amplifier according to the present invention.

Further, a sixth aspect of the present invention (corresponding to claim 6)
Comprises a distortion level detection circuit connected to an output of a third power amplifier and detecting a distortion level of the third power amplifier, and a control circuit connected to an output of the distortion level detection circuit, wherein the control The circuit controls an amplitude and a phase adjustment amount adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit so that a distortion level of the third power amplifier is minimized. A low distortion power amplifier according to a fourth aspect of the present invention.

A seventh aspect of the present invention (corresponding to claim 7)
A distribution circuit that distributes an input signal into two, a first matching circuit that is connected to one of output terminals of the distribution circuit and matches the input signal, and is connected to an output of the matching circuit, and A first power amplifier for linearly amplifying the signal, a second matching circuit connected to the output of the first power amplifier to match the amplified signal, and the other of the output terminals of the distribution circuit A third matching circuit connected to the input signal; a third power amplifier connected to an output of the third matching circuit for generating distortion of the matched signal; and A fourth matching circuit that is connected to the output of the second power amplifier and matches the distorted signal; and combines and outputs the output of the second matching circuit and the output of the fourth matching circuit. A synthesizing circuit,
A third power amplifier connected to the output of the combining circuit;
The combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4: 1, and the carrier signal output from the second matching circuit and the second matching circuit And the carrier signal output from the second power amplifier is combined with a phase difference of 180 degrees, and the distortion characteristic of the second power amplifier and the distortion characteristic of the third power amplifier are substantially the same. Power amplifier.

An eighth aspect of the present invention (corresponding to claim 8)
Comprises an output level detection circuit connected to the output of the third power amplifier, for detecting the output level of the third power amplifier, and a control circuit connected to the output of the output level detection circuit, The low distortion power amplifier according to the sixth aspect of the present invention, wherein the control circuit controls at least one of the first to fourth matching circuits according to the detected output level. .

The ninth invention (corresponding to claim 9)
Comprises a distortion level detection circuit connected to the output of the third power amplifier, for detecting a distortion level of the third power amplifier, and a control circuit connected to the output of the distortion level detection circuit, The low distortion power amplifier according to the sixth aspect of the present invention, wherein the control circuit controls at least one of the first to fourth matching circuits according to the detected distortion level. .

According to a tenth aspect of the present invention (corresponding to claim 10), a distribution circuit for dividing an input signal into two and an output terminal of the distribution circuit are connected to adjust the amplitude and phase of the input signal. A first vector adjustment circuit for
Connected to the output of the first vector adjustment circuit, a first power amplifier for linearly amplifying the output signal of the first vector adjustment circuit, and connected to the other output terminal of the distribution circuit, A second vector adjustment circuit for adjusting the amplitude and phase of the input signal, and a second vector adjustment circuit connected to an output of the second vector adjustment circuit for generating distortion of an output signal of the second vector adjustment circuit. Two power amplifiers; a 3 dB directional coupler having a first input terminal, a second input terminal, a first output terminal, and a second output terminal; and the first of the 3 dB directional couplers. A third power amplifier connected to an output terminal; a second output terminal of the 3 dB directional coupler and an output of the second power amplifier; Carrier wave output from output terminal A comparator for comparing the power with the power of the carrier output from the second power amplifier; and a control circuit connected to the comparator, wherein the output of the first power amplifier is the 3 dB directional The output of the second power amplifier is connected to the first input terminal of the coupler, and the output of the second power amplifier is connected to the second input terminal of the 3 dB directional coupler. The distortion characteristic of the third power amplifier is substantially the same, and the output power of the first power amplifier and the output power of the second power amplifier are provided at the first output terminal of the 3 dB directional coupler. The power combining ratio is 4: 1 and the phase difference between the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier is 180 degrees. , The second output of the 3 dB directional coupler In the power terminal, the output power of the first power amplifier and the output power of the second power amplifier have a combined ratio of 4 to 1, and the carrier signal output from the first power amplifier and the The phase difference between the carrier signal output from the second power amplifier and the carrier signal is set to 0 degree, and the control circuit controls the 3db
The comparator compares the ratio of the power of the carrier output from the second output terminal of the directional coupler to the power of the carrier output from the second power amplifier so that the result becomes 9: 1. A low-distortion power amplifier which controls the amount of phase and amplitude adjustment adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit.

An eleventh invention (corresponding to claim 11) is a distribution circuit for dividing an input signal into two, and connected to one of output terminals of the distribution circuit to adjust an amplitude and a phase of the input signal. A first vector adjustment circuit for
Connected to the output of the first vector adjustment circuit, a first power amplifier for linearly amplifying the output signal of the first vector adjustment circuit, and connected to the other output terminal of the distribution circuit, A second vector adjustment circuit for adjusting the amplitude and phase of the input signal, and a second vector adjustment circuit connected to an output of the second vector adjustment circuit for generating distortion of an output signal of the second vector adjustment circuit. Two power amplifiers; a 3 dB directional coupler having a first input terminal, a second input terminal, a first output terminal, and a second output terminal; and the first of the 3 dB directional couplers. A third power amplifier connected to an output terminal; a second output terminal of the 3 dB directional coupler and an output of the second power amplifier; Carrier wave output from output terminal A comparator for comparing the power ratio of the distortion with respect to the power ratio of the distortion to the carrier output from the second power amplifier, and a control circuit connected to the comparator, wherein the first power amplifier An output connected to the first input terminal of the 3 dB directional coupler;
An output of the second power amplifier is connected to a second input terminal of the 3 dB directional coupler, and a distortion characteristic of the second power amplifier is substantially the same as a distortion characteristic of the third power amplifier. And at the first output terminal of the 3 dB directional coupler, a combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4: 1,
And a phase difference between a carrier signal output from the first power amplifier and a carrier signal output from the second power amplifier is set to 180 degrees, and the second signal of the 3 dB directional coupler is The output terminal of the first power amplifier, the output power of the second power amplifier, the combined ratio of the output power is 4: 1, and the carrier signal output from the first power amplifier and The phase difference with the carrier signal output from the second power amplifier is 0 degree,
The control circuit calculates a ratio of a distortion power ratio to a carrier outputted from the second output terminal of the 3db directional coupler to a distortion power ratio to a carrier outputted from the second power amplifier. The result of comparison by the comparator is 1 to 9
A low-distortion power amplifier characterized in that the phase and amplitude adjustment amounts adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit are controlled such that:

A twelfth invention (corresponding to claim 12) is characterized in that when the output power from the third power amplifier is equal to or less than a predetermined value, the second power amplifier is turned off. A low distortion power amplifier according to any one of the first to eleventh aspects of the present invention.

According to a thirteenth aspect of the present invention (corresponding to claim 13), the synthesizing circuit includes a first input terminal, a second input terminal, a first input terminal and a second input terminal. A resistance connected between the first transmission line connected to the first input terminal, a second transmission line connected to the second input terminal, and an output of the first transmission line, An output terminal connected to the output of the second transmission line, wherein the first and second transmission lines have a characteristic impedance at a point connected to the first and second input terminals. The low distortion power amplifier according to any one of the first to ninth aspects of the present invention, wherein a characteristic impedance at a point connected to the terminal is larger.

A fourteenth aspect of the present invention (corresponding to claim 14) is characterized in that the first power amplifier and the third power amplifier are formed on the same semiconductor chip. A low distortion power amplifier according to any of the present inventions.

According to a fifteenth aspect of the present invention (corresponding to claim 15), the transistor forming the first power amplifier and the transistor forming the third power amplifier are formed on the same semiconductor chip. The first to first features
3 is a low distortion power amplifier according to any one of the present inventions.

According to the present invention, a predistortion compensating circuit can be formed in a small size without complicating the circuit as shown in FIG. 8, and a low distortion power amplifier can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below along with its operation.

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG.

In FIG. 1, a signal input from an input terminal 101 is distributed by a distribution circuit 103 into two signals. One of the outputs from the distribution circuit 103 is input to a power amplifier 104 for linearly amplifying a carrier signal, and the output is input to a synthesis circuit 106. The other output from the distribution circuit 103 is input to a power amplifier 105 for generating distortion. Power amplifier 10
5 is input to the other input terminal of the combining circuit 106, and the output of the combining circuit 106 is
And output from the output terminal 102.

Next, the present embodiment will be described in detail. For simplicity, the input signal is two waves having different frequencies.

The output voltage Vo when two waves having an amplitude of 1 and different frequencies are input to the power amplifier 107 is expressed by the following equation.

[0030]

[Equation 1] VO = AO (cosω1t + cosω2t) + BOL cos [(2ω1
-ω2) t + φ3L] + BOU cos [(2ω2-ω1) t + φ3U] where ω1 and ω2 are the angular frequencies of the input signal, and AO is the voltage of the output voltage signal whose angular frequencies are ω1 and ω2. , BOL and BOU are the amplitude components of the tertiary intermodulation distortion generated on the low frequency side and the high frequency side, respectively, and φ3L and φ3U are the tertiary intermodulation distortion voltages generated on the low frequency side and the high frequency side, respectively. This is the phase component. Note that the difference frequency component, harmonic component,
Higher-order terms of the fifth or higher order are omitted.

The power amplifier 105 is designed to have the same distortion characteristics as the power amplifier 107. That is, the output power VI1 of the power amplifier 105 when two waves having an amplitude of 1 and different frequencies are input can be expressed by the following equation.

[0032]

[Equation 2] VI1 = AI1 (cosω1t + cosω2t) + BI1L cos [(2
ω1−ω2) t + φ3L] + BI1U cos [(2ω2−ω1) t + φ3U] Here, there is a relationship of BOL / AO = BI1L / AI1, and BOU / AO = BI1U / AI1.

When two waves having an amplitude of 1 and different frequencies are input, the output voltage VI2 from the power amplifier 104 is
It can be expressed as the following equation.

[0034]

## EQU3 ## VI2 = AI2 (cosω1t + cosω2t) Here, the power amplifier 104 is adjusted so that AI2 = −2AI1. That is, the combined ratio of the output power of the power amplifier 104 and the output power of the power amplifier 105 is 4 to 1, and the carrier signal output from the power amplifier 104 and the carrier signal output from the power amplifier 105 are different. 18 phase difference
Combined at 0 degrees.

Then, the output voltage VIT after being synthesized by the synthesizing circuit 106 is expressed by the following equation.

[0036]

[Equation 4] VIT = AIT (cosω1t + cosω2t)-BITL cos [(2
ω1−ω2) t + φ3L] −BITU cos [(2ω2−ω1) t + φ3U] Here, BOL / AO = BITL / AIT and BOU / AO = BITU / AIT.

Therefore, by inputting such a VIT to the power amplifier 107, the third-order intermodulation distortion generated from the power amplifier 107 can be suppressed.

That is, the distortion characteristic of the power amplifier 105 is designed to be similar to that of the power amplifier 107, and the combined ratio of the output power of the power amplifier 104 and the output power of the power amplifier 105 is 4: 1. When the carrier signal output from the power amplifier 105 and the carrier signal output from the power amplifier 105 are combined with a phase difference of 180 degrees, the third-order intermodulation distortion generated from the power amplifier 107 can be suppressed.

In the present embodiment, the third-order intermodulation distortion has been described as an example. However, the distortion can be similarly reduced with respect to the fifth-order or higher-order distortion.

In this embodiment, for simplicity, the input signal is two continuous waves having different frequencies, but the distortion can be similarly reduced for other modulated waves.

As shown in FIG. 2, the output of the power amplifier 105 for generating distortion and the output of the power amplifier 107 are connected to modulation frequency trap circuits 206 and 209 having a small impedance at the modulation frequency, respectively. Thus, the distortion of the modulation frequency component generated from the power amplifier can be suppressed, and more effective distortion suppression can be obtained.

In FIG. 2, the trap circuit 206,
A similar effect can be obtained by setting 209 as a second harmonic trap circuit having a small impedance at the second harmonic of the carrier.

Further, in FIGS.
By turning off the power amplifier 105 when the power output from 7 is smaller than a certain value, the power consumed by the predistortion compensating circuits 108 and 210 can be reduced. That is, when the power output from the power amplifier 107 is smaller than a certain value, the distortion generated in the power amplifier 107 becomes negligibly small. Therefore, in this case, since it is not necessary to perform distortion compensation by the predistortion compensation circuits 108 and 210, the power amplifier 105 can be turned off.

As the combining circuit, in addition to the 3 dB directional coupler and the Wilkinson type combiner, a modified version of the Wilkinson type combiner as shown in FIG. 7 can be considered.

The combining circuit shown in FIG. 7 has input terminals 701 and 70
2, resistor 704, transmission lines 705 and 706, output terminal 7
In the transmission lines 705 and 706, the characteristic impedance at the point connected to the output terminal 703 is larger than the characteristic impedance at the point connected to the input terminals 701 and 702.

The power amplifier 104 and the power amplifier 10
7 was formed on the same semiconductor chip. Therefore, there is an advantage that equivalent distortion characteristics can be easily obtained.

According to this configuration, a frequency characteristic wider than that of a normal Wilkinson type synthesizer can be obtained.

The power amplifier 104 of the present embodiment is an example of the first power amplifier of the present invention, and the power amplifier 105 of the present embodiment is an example of the second power amplifier of the present invention. The power amplifier 107 of the present embodiment is an example of the third power amplifier of the present invention, and the trap circuit 2 of the present embodiment
06 is an example of the first modulation frequency trap circuit of the present invention, the trap circuit 209 of this embodiment is an example of the second modulation frequency trap circuit of the present invention, and the trap circuit 206 of this embodiment is This is an example of the first harmonic trap circuit of the present invention, the trap circuit 209 of the present embodiment is an example of the second harmonic trap circuit of the present invention, and the input terminal 701 of the present embodiment is The input terminal 702 of the present embodiment is an example of the second input terminal of the present invention, and the transmission line 705 of the present embodiment is the first transmission line of the present invention. The transmission line 706 of the present embodiment is an example of the second transmission line of the present invention.

(Embodiment 2) Embodiment 2 of the present invention will be described with reference to FIG.

In FIG. 3, a signal input from an input terminal 101 is distributed by a distribution circuit 103 into two signals. One of the outputs from the distribution circuit 103 is input to the vector adjustment circuit 304, where the amplitude and phase of the signal are adjusted, and then input to the power amplifier 305 for linearly amplifying the carrier signal. The signal is input to the circuit 106. The other output from the distribution circuit 303 is input to the vector adjustment circuit 306, and after adjusting the amplitude and phase of the signal, the power amplifier 307 for generating distortion.
And its output is input to the synthesis circuit 106.
An output from the combining circuit 106 is connected to an input of the power amplifier 107.

As in the first embodiment, power amplifier 307
Are designed to have the same distortion characteristics as the power amplifier 107. Further, similarly to the first embodiment, the power amplifier 3
The output from the power amplifier 05 and the output from the power amplifier 307 are combined so that the power ratio is 4: 1 and the phases are opposite. By adjusting the amplitude and phase adjustment amounts adjusted by the vector adjustment circuits 304 and 306 in this manner, the power amplifier 307 is adjusted.
Can be reduced.

In order to improve the accuracy of distortion suppression,
A circuit configuration as shown in FIG. 4 is conceivable.

In the circuit of FIG. 4, a level detection circuit 410 is connected to the output of the power amplifier 107, and the vector adjustment circuits 304 and 30 are controlled by the control circuit 411 according to the output level.
Adjust 6 to an optimal value. By performing such control, the power amplifier 10 over a wide dynamic range can be used.
7 can be reduced.

In FIG. 4, the level detection circuit 410 detects the distortion level of the power amplifier 409, and the control circuit 411 adjusts the vector adjustment circuits 404 and 406 so that the distortion level is minimized. By performing such control, a large amount of distortion suppression can be obtained.

Further, the vector adjustment circuits 404 and 406
, The matching circuits 504, 50 as shown in FIG.
The same effect can be obtained by making at least one of 6, 507 and 509 variable. However, FIG.
Here, illustration of the bias circuit of the transistors 305 and 308 is omitted.

The power amplifier 305 and the power amplifier 30
7 were formed on the same semiconductor chip as in the first embodiment.

Note that the vector adjustment circuit 3 of the present embodiment
04 is an example of the first vector adjustment circuit of the present invention, the vector adjustment circuit 306 of the present embodiment is an example of the second vector adjustment circuit of the present invention, and the power amplifier 305 of the present embodiment is The power amplifier 305 of the present embodiment is an example of the first power amplifier of the present invention, and the power amplifier 305 of the present embodiment is an example of the second power amplifier of the present invention. This is an example of a circuit, the level detection circuit 410 of the present embodiment is an example of a distortion level detection circuit of the present invention, the matching circuit 504 of the present embodiment is an example of a first matching circuit of the present invention, Matching circuit 5 of the present embodiment
06 is an example of the second matching circuit of the present invention, the matching circuit 507 of the present embodiment is an example of the third matching circuit of the present invention, and the matching circuit 509 of the present embodiment is the second matching circuit of the present invention. It is an example of the fourth matching circuit.

(Embodiment 3) Embodiment 3 of the present invention will be described with reference to FIG.

In FIG. 6, a signal input from an input terminal 101 is distributed by a distribution circuit 103 into two signals. One of the outputs from the distribution circuit 103 is input to a vector adjustment circuit 304, where the amplitude and phase of the signal are adjusted, and then input to a power amplifier 305 for linearly amplifying a carrier signal, and the output is 3 dB. Directional coupler 60
8 is input. The other output from the distribution circuit 103 is input to the vector adjustment circuit 306, where the amplitude and phase of the signal are adjusted, and then input to the power amplifier 307 for generating distortion. The signal is input to the other input terminal of the coupler 608. These 3d
The two signals input to the B-directional coupler 608 have a carrier phase difference of 90 degrees and a power ratio of 2 to 1 (the output power from the power amplifier 605 is 2 times the power of the power amplifier 607).
Times). With this setting, the power of VIT and VIT2 in the following equation is output from the two output terminals of the 3 dB directional coupler 608.

[0060]

[Equation 4] VIT = AIT (cosω1t + cosω2t)-BITL cos [(2
ω1-ω2) t + φ3L]-BITU cos [(2ω2-ω1) t + φ3U]

[0061]

[Equation 5] VIT2 = 3 AIT (cosω1t + cosω2t) + BITL cos
[(2ω1-ω2) t + φ3L] + BITU cos [(2ω2-ω1) t + φ
3U] In practice, the phase of each carrier is 90 degrees out of phase, but it is ignored here. The terminal from which VIT is output is referred to as a first output terminal, and the terminal from which VIT2 is output is referred to as a second output terminal. The output from the first output terminal of the 3 dB directional coupler 608 is the power amplifier 1
07. A second output of the 3 dB directional coupler 608 is input to a first input terminal of the comparator 610. The second input terminal of the comparator 610 has a power amplifier 3
07 is input and monitored. In order to reduce the distortion of the power amplifier 107 by the predistortion compensation circuit 612, the power of the carrier output from the second terminal of the 3 dB directional coupler 608 and the power of the carrier output from the power amplifier 307 are reduced. Must be 9: 1. Therefore, conversely, the control circuit 611 controls the vector adjustment circuits 304 and 306 such that the power ratio becomes 9: 1, whereby the distortion generated from the power amplifier 107 can be suppressed stably. Here, the signal input to the second input terminal of the comparator 610 is the output of the power amplifier 307, but the signal input to the second input terminal of the comparator 610 is the output of the power amplifier 305, The control circuit 6 controls the ratio of the carrier power output from the second output terminal of the 3 dB directional coupler 608 to the carrier power output from the power amplifier 605 to 9: 4.
By controlling the vector adjustment circuits 304 and 306 according to 11, the distortion generated from the power amplifier 609 can be similarly suppressed with high accuracy.

Further, in the circuit configuration as shown in FIG. 6, the power ratio of the distortion signal output from the second output terminal of the 3 dB directional coupler 608 to the carrier wave by the comparator 610 and the second power amplifier 307 By controlling the vector adjustment circuits 304 and 306 such that the power ratio of the distortion signal output from the to the carrier is 9: 1, the distortion of the power amplifier 107 can be similarly suppressed.

The power amplifier 305 and the power amplifier 10
7 were formed on the same semiconductor chip as in the first embodiment.

In this embodiment, the power amplifier 10
4 and the power amplifier 107 are described as being formed on the same semiconductor chip, but the present invention is not limited to this, and the transistors forming the power amplifier 104 and the transistors forming the power amplifier 107 may be formed on the same semiconductor chip.

In this embodiment, the power amplifier 30
5 and the power amplifier 107 have been described as being formed on the same semiconductor chip, but the present invention is not limited to this, and the transistors forming the power amplifier 305 and the transistors forming the power amplifier 107 may be formed on the same semiconductor chip.

As described above, according to the configuration of this embodiment, the output power of the carrier output from the power amplifier for linearly amplifying the carrier and the output power of the carrier output from the power amplifier for generating the distortion are obtained. Output power ratio of 4
By making the distortion characteristic generated by the power amplifier for generating distortion equal to the distortion characteristic of the power amplifier connected to the output of the predistortion circuit, the circuit scale can be increased without increasing the circuit scale. It is possible to configure a predistortion compensation circuit and reduce distortion of the power amplifier.

[0067]

As is apparent from the above description, the present invention can provide a low distortion power amplifier which does not increase the circuit scale.

[Brief description of the drawings]

FIG. 1 is a block diagram of Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a low distortion power amplifier according to Embodiment 1 of the present invention.

FIG. 3 is a block diagram of a low distortion power amplifier according to Embodiment 2 of the present invention.

FIG. 4 is a block diagram of a low distortion power amplifier according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram of a low distortion power amplifier according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a low distortion power amplifier according to Embodiment 3 of the present invention.

FIG. 7 is a circuit diagram of a synthesis circuit according to the first embodiment of the present invention.

FIG. 8 is a block diagram of a conventional low distortion power amplifier.

[Explanation of symbols]

Reference Signs List 101 input terminal 102 output terminal 103 distribution circuit 104, 105, 107 power amplifier 106 synthesis circuit 108 predistortion compensation circuit 206, 209 modulation frequency trap circuit or second harmonic trap circuit 210 predistortion compensation circuit 304, 306 vector Adjustment circuit 310 Predistortion compensation circuit 410 Level detection circuit 411 Control circuit 412 Predistortion compensation circuit 513 Control circuit 514 Predistortion compensation circuit 608 3 dB directional coupler 610 Comparator 611 Control circuit 701, 702 Input terminal 703 Output terminal 704 Resistance 705, 706 Transmission line 801 Input terminal 802 Output terminal 803, 806 Distribution circuit 804, 807 Vector adjustment circuit 805, 808, 809, 812 Power amplifier 810, 811 Synthesis circuit

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Isono 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa F-term (reference) in Matsushita Communication Industrial Co., Ltd. 5J069 AA01 AA21 AA41 CA21 CA92 FA19 HA25 KA00 KA13 KA17 KA29 KA68 KC06 KC07 MA11 SA13 TA01 5J090 AA01 AA21 AA41 CA21 CA92 DN02 FA19 GN02 GN04 HA25 HN07 KA00 KA13 KA17 KA29 KA68 MA11 SA13 TA01 5J091 AA01 AA21 AA41 CA21 CA92 FA19 HA25 KA13 KA13 KA13 KA13 KA13 KA13

Claims (15)

[Claims] 1. A distribution circuit for dividing an input signal into two, a first power amplifier connected to one of output terminals of the distribution circuit for linearly amplifying the input signal, and an output terminal of the distribution circuit And a second power amplifier for generating distortion of the input signal, and a combining circuit that combines and outputs the output of the first power amplifier and the output of the second power amplifier. A third power amplifier connected to the output of the synthesis circuit, wherein the distortion characteristics of the second power amplifier and the distortion characteristics of the third power amplifier are substantially the same; The combined ratio of the output power of the power amplifier and the output power of the second power amplifier is 4 to 1, and the carrier signal output from the first power amplifier and the output from the second power amplifier are output. Phase difference of 18 Low distortion power amplifier, characterized by combining in degrees. 2. A first modulation frequency trap circuit connected to an output of the second power amplifier and having an impedance at a modulation frequency of a modulation wave of the input signal smaller than a predetermined value; 2. The low distortion power amplifier according to claim 1, further comprising a second modulation frequency trap circuit connected to an output and having an impedance at a modulation frequency of a modulation wave of the input signal smaller than a predetermined value. 3. A first harmonic trap circuit connected to an output of the second power amplifier and having an impedance at a second harmonic of the input signal smaller than a predetermined value, and an output of the third power amplifier. 2. A low distortion power amplifier according to claim 1, further comprising: a second harmonic trap circuit connected to the second input terminal and having a second harmonic impedance of the input signal smaller than a predetermined value. 4. A distribution circuit for dividing an input signal into two, a first vector adjustment circuit connected to one of output terminals of the distribution circuit for adjusting an amplitude and a phase of the input signal, A first power amplifier connected to the output of the vector adjustment circuit for linearly amplifying the adjusted signal; connected to the other output terminal of the distribution circuit to adjust the amplitude and phase of the input signal And a second power amplifier connected to the output of the second vector adjustment circuit for generating distortion of the adjusted signal; and A combining circuit that combines and outputs an output of the second power amplifier and an output of the second power amplifier; and a third power amplifier connected to an output of the combining circuit. Third The distortion characteristics of the power amplifiers are substantially the same, and the combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4: 1; And a carrier signal output from the second power amplifier and a carrier signal output from the second power amplifier with a phase difference of 180 degrees. 5. An output level detection circuit connected to an output of the third power amplifier for detecting an output level of the third power amplifier, and a control circuit connected to an output of the output level detection circuit. The control circuit, according to the detected output level,
The low-distortion power amplifier according to claim 4, wherein an amount of amplitude and phase adjustment adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit is controlled. 6. A distortion level detection circuit connected to an output of a third power amplifier for detecting a distortion level of the third power amplifier, and a control circuit connected to an output of the distortion level detection circuit. The control circuit controls the amplitude and phase adjustment amounts adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit so that the distortion level of the third power amplifier is minimized. 5. The low distortion power amplifier according to claim 4, wherein: 7. A distribution circuit that distributes an input signal into two, a first matching circuit that is connected to one of output terminals of the distribution circuit and matches the input signal, and that is connected to an output of the matching circuit, A first power amplifier for linearly amplifying the matched signal; a second matching circuit connected to an output of the first power amplifier to match the amplified signal; and an output of the distribution circuit. A third matching circuit connected to the other of the terminals to match the input signal; and a second power amplifier connected to the output of the third matching circuit to cause distortion of the matched signal. A fourth matching circuit connected to the output of the second power amplifier and matching the distorted signal; and combining the output of the second matching circuit and the output of the fourth matching circuit. And a synthesis circuit that outputs A third power amplifier connected to the output of the combining circuit, a combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4 to 1, and the second matching The carrier signal output from the circuit and the carrier signal output from the second matching circuit are combined with a phase difference of 180 degrees, and the distortion characteristics of the second power amplifier and the distortion of the third power amplifier are combined. A low distortion power amplifier having substantially the same characteristics. 8. An output level detection circuit connected to an output of the third power amplifier for detecting an output level of the third power amplifier, and a control circuit connected to an output of the output level detection circuit. The control circuit, according to the detected output level,
7. The low distortion power amplifier according to claim 6, wherein at least one of the first to fourth matching circuits is controlled. 9. A distortion level detection circuit connected to an output of the third power amplifier for detecting a distortion level of the third power amplifier, and a control circuit connected to an output of the distortion level detection circuit. The control circuit, according to the detected distortion level,
7. The low distortion power amplifier according to claim 6, wherein at least one of the first to fourth matching circuits is controlled. 10. A distribution circuit for dividing an input signal into two, a first vector adjustment circuit connected to one of output terminals of the distribution circuit for adjusting an amplitude and a phase of the input signal, A first power amplifier connected to the output of the vector adjustment circuit for linearly amplifying the output signal of the first vector adjustment circuit, and connected to the other output terminal of the distribution circuit, A second vector adjustment circuit for adjusting the amplitude and phase, and a second power connected to an output of the second vector adjustment circuit for generating distortion of an output signal of the second vector adjustment circuit. An amplifier; a 3 dB directional coupler having a first input terminal, a second input terminal, a first output terminal, and a second output terminal; and a first output terminal of the 3 dB directional coupler. Connected number A power amplifier connected to the second output terminal of the 3 dB directional coupler and the output of the second power amplifier, and a carrier output from the second output terminal of the 3 db directional coupler. A comparator for comparing the power with the power of the carrier output from the second power amplifier; and a control circuit connected to the comparator, wherein the output of the first power amplifier is the 3 dB directional An output of the second power amplifier is connected to a second input terminal of the 3 dB directional coupler; a distortion characteristic of the second power amplifier; The distortion characteristics of the third power amplifier are substantially the same, and at the first output terminal of the 3 dB directional coupler, the output power of the first power amplifier and the output power of the second power amplifier The power combining ratio is 4: 1 and The phase difference between the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier is 18
At the second output terminal of the 3 dB directional coupler, the combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4: 1. And the phase difference between the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier is 0 degrees, and the control circuit is configured to control the 3db direction. The comparator compares the ratio of the power of the carrier output from the second output terminal of the sexual coupler to the power of the carrier output from the second power amplifier so that the result becomes 9: 1. A low-distortion power amplifier, which controls a phase and amplitude adjustment amount adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit. 11. A distribution circuit for dividing an input signal into two, a first vector adjustment circuit connected to one of output terminals of the distribution circuit for adjusting the amplitude and phase of the input signal, A first power amplifier connected to the output of the vector adjustment circuit for linearly amplifying the output signal of the first vector adjustment circuit, and connected to the other output terminal of the distribution circuit, A second vector adjustment circuit for adjusting the amplitude and phase, and a second power connected to an output of the second vector adjustment circuit for generating distortion of an output signal of the second vector adjustment circuit. An amplifier; a 3 dB directional coupler having a first input terminal, a second input terminal, a first output terminal, and a second output terminal; and a first output terminal of the 3 dB directional coupler. Connected number And a power amplifier connected to the second output terminal of the 3 dB directional coupler and the output of the second power amplifier, for a carrier output from the second output terminal of the 3 db directional coupler. A comparator for comparing the power ratio of the distortion and the power ratio of the distortion with respect to the carrier outputted from the second power amplifier; and a control circuit connected to the comparator, wherein the output of the first power amplifier is provided. Is connected to the first input terminal of the 3 dB directional coupler, the output of the second power amplifier is connected to the second input terminal of the 3 dB directional coupler, and the second power The distortion characteristic of the amplifier and the distortion characteristic of the third power amplifier are substantially the same, and at the first output terminal of the 3 dB directional coupler, the output power of the first power amplifier, Output power of the second power amplifier And the phase difference between the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier is 18: 1.
At the second output terminal of the 3 dB directional coupler, the combined ratio of the output power of the first power amplifier and the output power of the second power amplifier is 4: 1. And the phase difference between the carrier signal output from the first power amplifier and the carrier signal output from the second power amplifier is 0 degrees, and the control circuit is configured to control the 3db direction. The result of comparing the ratio of the power ratio of the distortion with respect to the carrier outputted from the second output terminal of the sexual coupler to the power ratio of the distortion with respect to the carrier outputted from the second power amplifier by the comparator is 1 Vs. 9
A low-distortion power amplifier, which controls a phase and amplitude adjustment amount adjusted by the first vector adjustment circuit and / or the second vector adjustment circuit so that 12. The low distortion according to claim 1, wherein when the output power from the third power amplifier is equal to or less than a predetermined value, the second power amplifier is turned off. Power amplifier. 13. The combination circuit, comprising: a first input terminal; a second input terminal; a resistor connected between the first input terminal and the second input terminal; A first transmission line connected to the second transmission line connected to the second input terminal, an output of the first transmission line, and an output terminal connected to the output of the second transmission line. Wherein, of the first and second transmission lines, the characteristic impedance of a point connected to the output terminal is larger than the characteristic impedance of a point connected to the first and second input terminals. The low-distortion power amplifier according to claim 1. 14. The low distortion power amplifier according to claim 1, wherein said first power amplifier and said third power amplifier are configured on the same semiconductor chip. 15. The transistor according to claim 1, wherein a transistor forming the first power amplifier and a transistor forming the third power amplifier are formed on the same semiconductor chip. Low distortion power amplifier.