JP2002204131A - Power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power amplifier in which intermodulation distortion being generated in the amplifier is reduced while decreasing the number of components. SOLUTION: The power amplifier comprises a first balun outputting first and second signals having opposite phases based on a synthetic signal of two signals having different frequencies, a first amplifier outputting a first amplification signal containing a frequency component of the frequency difference between two signals from the first signal, a second amplifier outputting a second amplification signal containing a frequency component of the frequency difference between two signals from the second signal, and a second balun outputting the synthetic signal of first and second amplification signals. Frequency components contained in the second amplification signal are inputted between the first balun and the second balun through the first amplifier and reduced, and frequency components contained in the first amplification signal are inputted between the first balun and the second balun through the second amplifier and reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power amplifier mainly used in a mobile communication base station such as a portable telephone.

[0002]

2. Description of the Related Art In recent years, a power amplifier having a highly efficient and linear characteristic as much as possible has been used in a transmitter of a base station of a mobile communication device in order to amplify a large number of signal channels at once. is needed. In order to make the characteristics of the power amplifier as linear as possible, for example, it is indispensable to reduce distortion of the power amplifier itself in addition to employing distortion compensation such as a feedforward method.

FIG. 31 is a diagram showing a conventional power amplifier 600.

The power amplifying device 600 has an input terminal 601.
, Output terminals 602, baluns 603 and 604, and amplifiers 605 and 606. Amplifiers 605 and 606 are
Amplifying elements 611 and 612 and an input-side matching circuit 613;
614, output-side matching circuits 615 and 616, input-side bias circuit capacitors 617 and 618, and output-side bias circuit capacitors 619 and 620. Amplifiers 605 and 606 operate as push-pull amplifiers. Each of capacitors 619 and 620 is actually composed of a plurality of capacitors. That is,
A capacitor having a low impedance at a predetermined signal frequency; and a capacitor having a low impedance at a frequency corresponding to a frequency difference (frequency interval) when a plurality of signals are input. By providing the output side bias circuit capacitors 619 and 620, the intermodulation distortion generated in the amplifier can be suppressed, and the characteristics of the power amplifier can be made as linear as possible.

[0005]

In the conventional power amplifier 600, however, capacitors 619 and 620 are connected to the bias circuits of the push-pull amplifiers 605 and 606, respectively.
And the number of parts increases. In addition, since the capacitors 619 and 620 generally need to have a large capacity and a low resistance, an increase in the number of components increases the overall circuit scale. Further, the degree of suppression of intermodulation distortion varies depending on the frequency interval of a plurality of signals input to the amplifier.

It is an object of the present invention to reduce the number of parts,
An object of the present invention is to provide a power amplifier that reduces intermodulation distortion generated in the amplifier.

[0007]

SUMMARY OF THE INVENTION A power amplifier according to the present invention comprises:
An input unit for inputting a synthesized signal obtained by synthesizing two signals having different frequencies, a first output unit for outputting a first signal having a first phase, and a second phase opposite to the first phase A first balun having a second output unit for outputting a second signal having a first signal, and a second balun having a frequency component consisting of a difference between the frequencies of the two signals by receiving and amplifying the first signal. A first amplifier that outputs one amplified signal;
By receiving and amplifying the second signal, a second signal including a frequency component consisting of a frequency difference between the two signals is obtained.
A second amplifier that outputs an amplified signal of the first and second input sections, and a first input section and a second input section.
And a second balun having an output unit for outputting a composite signal of the signal input from the input unit of the first balun. From the first amplifier to the first amplification path reaching the first input section of the second balun via the first amplifier, the frequency component is reduced, and the frequency component is reduced. The first amplified signal is input to a first input section of the second balun, and a frequency component included in the first amplified signal is converted from a second output section of the first balun to the second input section. The frequency component is reduced by inputting the signal to a second amplification path reaching the second input portion of the second balun via an amplifier, and the second amplified signal having the reduced frequency component is converted into a second amplified signal. , A second input of the second balun. This achieves the above object.

A phase of a frequency component included in the amplified signal;
When the phase of the input frequency component is different, the frequency component may be reduced.

[0009] An impedance element connected between the first amplifying path and the second amplifying path and having a characteristic of passing the frequency component is further provided, and the first amplifying element is connected via the impedance element. The frequency component included in the signal and the frequency component included in the second amplified signal may be input to a second amplification path and the first amplification path, respectively.

[0010] The frequency component connected in series with the impedance element and included in the first amplified signal,
The apparatus may further include a phase shifter that receives the frequency components included in the second amplified signal, adjusts the phase of each frequency component, and outputs the signals in opposite phases.

The first amplifier path is connected to the first amplification path.
A first directional coupler for receiving the amplified signal of
And a second directional coupler that is connected to the amplification path and receives the second amplified signal, wherein the first directional coupler extracts a frequency component of the first amplified signal. By outputting to the second directional coupler and receiving the frequency component included in the second amplified signal from the second directional coupler, the frequency component is reduced, and the frequency component is reduced. Generates a first amplified signal, the second directional coupler extracts a frequency component of the second amplified signal, outputs the frequency component to the first directional coupler, and outputs the first amplified signal. By receiving a frequency component included in the first amplified signal from the directional coupler, the frequency component may be reduced, and the second amplified signal having the reduced frequency component may be generated.

The first directional coupler is provided between an output of the first directional coupler and an input of the second directional coupler, and receives the frequency component included in the first amplified signal and receives the frequency component. A first phase shifter that adjusts the phase and outputs a signal having an opposite phase to the frequency component included in the second amplified signal, an output of the second directional coupler, and a first directional coupler. Provided between the input and the second amplified signal, receives the frequency component included in the second amplified signal, adjusts the phase of the frequency component, and outputs a signal having an opposite phase to the frequency component included in the first amplified signal. And a second phase shifter.

[0013] The first directional coupler and the second directional coupler may have a coupling degree of at least 3 dB or more with respect to the frequency component.

The first amplifier path is connected to the first amplification path.
A first directional coupler for extracting and outputting a frequency component of the amplified signal of the second amplified signal;
And a second directional coupler that extracts and outputs a frequency component of the amplified signal of the second amplified signal, wherein the first amplifier outputs the second amplified signal that is output from the second directional coupler. By receiving the included frequency component, the frequency component is reduced to generate a first amplified signal having the reduced frequency component, and the second amplifier is output from the first directional coupler. Receiving the frequency component included in the first amplified signal, the frequency component may be reduced, and a second amplified signal having the reduced frequency component may be generated.

[0015] The first directional coupler and the second directional coupler may have a coupling degree of at least 3 dB or more with respect to the frequency component.

[0016] The impedance element may be a capacitive element.

[0017] The impedance element may be an inductive element.

[0018] The impedance element may be a low-pass filter.

[0019] The device may have two or more impedance elements having different self-resonant frequencies.

The impedance element may have a low impedance with respect to the frequency component.

[0021] The impedance element may be connected between an output of the first amplifier and an output of the second amplifier.

The first amplifier includes a first matching circuit for matching an impedance on an input side of the first amplifier, a first amplifying element connected to an output of the first matching circuit, A second matching circuit connected to the output of the first amplifying element and matching the impedance of the output side of the first amplifier, wherein the second amplifier is connected to the input side of the second amplifier. A third matching circuit for matching impedance;
A second amplifying element connected to the output of the third matching circuit, and a fourth matching circuit connected to the output of the second amplifying element for matching the impedance on the output side of the second amplifier. May be provided.

[0023] The impedance element may be connected between an output of the first amplification element and an output of the second amplification element.

[0024] The impedance element may be connected between an output of the first amplifying element and an output of the fourth matching circuit.

[0025] The impedance element may be connected between an output of the second matching circuit and an input of the fourth matching circuit.

The first amplification path is connected to the first amplification path.
Having the characteristic of passing the frequency component of the amplified signal of
And a second impedance element connected to the second amplification path and having a characteristic of passing a frequency component of the second amplified signal, wherein the first amplifier has a second impedance element. By receiving a frequency component included in the second amplified signal via an impedance element, the frequency component is reduced, and a first amplified signal with the reduced frequency component is generated, and the second amplifier is generated. Receives a frequency component included in the first amplified signal via a first impedance element, thereby reducing the frequency component and generating a second amplified signal having the reduced frequency component. Is also good.

[0027] The impedance element may be a low-pass filter.

A first amplifier provided between the output of the first amplifier and the first input of the second balun, for shifting the phase of the input signal by 90 degrees in a predetermined direction and outputting the shifted signal;
And the output of the second amplifier and the second input of the second balun, and outputs the phase of the input signal shifted by 90 degrees in a predetermined direction. A second phase shifter, wherein the second balun is a first phase shifter.
And an impedance element that connects the second input unit and the second input unit and has a characteristic of passing the frequency component.

The first amplifier path is connected to the first amplification path,
Having the characteristic of passing the frequency component of the amplified signal of
And a second low-pass filter connected to the second amplification path and having a characteristic of passing a frequency component of the second amplified signal; and a first low-pass filter; The second low-pass filter is connected in series, receives the frequency component included in the first amplified signal, and the frequency component included in the second amplified signal, and adjusts the phase of each frequency component. It may further include a phase shifter that adjusts and outputs the signals in opposite phases.

The power supply further includes a power supply that outputs the frequency component signal at a phase opposite to the phase of the frequency component signal, wherein the second balun receives the signal output from the power supply, The signal may be input to the first amplification path and the second amplification path via one input unit and the second input unit.

An impedance element connected to one of the output of the first amplifier and the output of the second amplifier and having a characteristic of transmitting the frequency component;
The second balun receives the signal output from the impedance element, and receives the first amplification path and the second amplification path via the first input section and the second input section. May be entered.

The detector further includes a detector for performing envelope detection based on the combined signal input to the input unit of the first balun, extracting and outputting the frequency component, and the second balun includes: The signal output from the detection unit may be received, and may be input to the first amplification path and the second amplification path via the first input unit and the second input unit.

[0033]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a power amplifier 100 according to a first embodiment.
The power amplifier 100 has an input terminal 101 and an input 103.
a, a first balun 103 having a first output 103b and a second output 103c, an input 105a and an output 1
05b, an amplifier 106 having an input 106a and an output 106b, a capacitor 107 as an impedance element, a second balun 104 having a first input 104b, a second input 104c and an output 104a, and an output And a terminal 102.

The connection relation in the power amplifier 100 is as follows. The input terminal 101 is connected to an input 103a of the balun 103 and a first output 103 of the balun 103.
b and the second output 103c are respectively connected to the amplifier 105
Input 105a and the input 106a of the amplifier 106. Output 105b of amplifier 105 and amplifier 1
06 is connected to a first input 104b and a second input 104c of the second balun 104, respectively. The output 104a of the balun 104 is connected to the output terminal 102.
Connected to. Further, the capacitor 107 is connected to the amplifier 10.
5 and the output 106b of the amplifier 106. Hereinafter, a path from the first output 103b of the balun 103 to the first input 104b of the balun 104 via the amplifier 105 will be referred to as a first amplification path 16b.
Let it be 1. Further, the second input 103 of the balun 104 is supplied from the second output 103 c of the balun 103 via the amplifier 106.
A path that reaches the section 04c is referred to as a second amplification path 162.

FIG. 2 shows a specific circuit configuration of the power amplifier 100. The amplifier 105 includes an amplifying element 111 composed of a transistor, an input-side matching circuit 113 for matching input-side impedance, an output-side matching circuit 115 for matching output-side impedance, and an input-side bias circuit for applying a bias to the input side. 131 and an output-side bias circuit 133 for applying a bias to the output side. The input side matching circuit 113 and the input side bias circuit 131 are connected to the gate of the amplification element 111. Further, the output side matching circuit 115 and the output side bias circuit 133 are connected to the drain of the amplification element 111. The input side bias circuit 131 includes a transmission line 121 and a capacitor 117 for the input side bias circuit. The output-side bias circuit 133 includes a transmission line 123 and a capacitor 119 for the output-side bias circuit. The transmission lines 121 and 123 are, for example, quarter wavelength lines of the input signal frequency. The capacitors 117 and 119 are capacitors having low impedance at the input signal frequency.

On the other hand, the amplifier 106 of the power amplifier 100
Has an amplifying element 112 composed of a transistor, an input side matching circuit 114, an output side matching circuit 116, an input side bias circuit 132, and an output side bias circuit 134. The input side matching circuit 114 and the input side bias circuit 132 are connected to the gate of the amplification element 112.
Further, an output side matching circuit 116 and an output side bias circuit 134 are connected to the drain of the amplification element 112.
The input-side bias circuit 132 includes the transmission line 122 and the capacitor 118 for the input-side bias circuit. The output side bias circuit 134 includes the transmission line 124 and the capacitor 120 for the output side bias circuit.

Next, referring to FIG.
Will be described. FIG. 3 is a block diagram illustrating signal waveforms at various parts of the power amplifier 100. The unbalanced signal input from the input terminal 101 is converted by the balun 103 into a first signal and a second signal,
Is output from the output 103b and the second output 103c. At this time, from the two outputs, 18
A balanced signal having a phase difference of 0 ° is output. That is, the balun 103 converts one input signal into two signals whose phases are shifted from each other by 180 °, and outputs each of them. The first signal and the second signal are amplified by amplifiers 105 and 106 that operate as push-pull amplifiers, respectively. The amplified first signal and second signal are input to the balun 104 from the first input 104b and the second input 104c of the balun 104, respectively, and are converted into an unbalanced amplified signal. In other words, the balun 104 amplifies and converts two input signals whose phases are shifted from each other by 180 ° into one signal,
Output. The converted amplified signal is output from output terminal 102. As a result, the signal input from the input terminal 101 is output at the output terminal 102 as an amplified signal.

The bias circuit 131 (FIG. 2) and the bias circuit 133 (FIG. 2) of the amplifier 105
5 is high impedance at the input signal frequency. That is, the bias circuit 1
31 (FIG. 2) and the bias circuit 133 (FIG. 2) do not affect the operation of the signal. This is the same for the bias circuit of the amplifier 106.

Now, consider a case where two signals having a frequency interval sufficiently smaller than the signal frequency are input to the input terminal 101. Even when two signals are input, the power amplifier 100 performs the above-described basic operation. However, in this case, intermodulation distortion occurs due to the nonlinearity of the amplifier. Now, let the frequencies of the two input signals be f1 and f2 (for example, f1 is 2000 MHz and f2 is 2).
010 MHz). FIG. 4A is a waveform diagram of signals of frequencies f1 and f2. Subsequently, FIG.
FIG. 5 is a waveform diagram of a synthesized signal obtained by synthesizing signals of the frequency f1 and the frequency f2. FIG. 4C is a diagram showing the waveforms of the first signal and the second signal converted and output by the balun 103 (FIG. 3). Converted first
And the second signal are amplified by amplifiers 105 and 106, respectively.

Consider the case where the first signal is amplified as an example. For example, assume that the amplifier 105 (FIG. 3) has a characteristic of amplifying the amplitude twice. (A) of FIG.
, The signal waveform of the input signal is denoted by F, and the signal waveform of the ideal amplified signal is denoted by F ′. However, the signal waveform of the actual amplified signal is not represented as F ′, but becomes a signal waveform as shown by F ″ in FIG. 5B. This is due to distortion caused by the nonlinearity of the amplifier 105. As the signal waveform F ″ approaches the apex of the envelope, linear amplification cannot be obtained, and a phase shift occurs.

FIG. 6 shows a spectrum distribution obtained by analyzing the components of the signal waveform of F '(FIG. 5 (a)). FIG. 6 (a)
Shows the frequency spectrum of two signal waves of frequencies f1 and f2 before amplification. The absolute value of the difference between the frequencies f1 and f2 (=
| F1−f2 |) is assumed to be Δf. Hereinafter, | f1-f2 |
Alternatively, Δf is referred to as a frequency interval.

Among the intermodulation distortions, the most problematic one is the third-order distortion. As shown in FIG. 6B, the third-order distortion occurs at the frequencies 2f1-f2 and 2f2-f1. One of the factors that cause the third-order intermodulation distortion is the frequency Δf generated by the nonlinearity of the amplifier 105.
The component (FIG. 6B) and the signal frequency f1 (or f2)
It is believed that the components are again mixed in the push-pull amplifier. Therefore, if the generated frequency Δf component can be reduced as shown in FIG. 6D, the generated third-order intermodulation distortion can be reduced. Note that the frequency Δf component is equal to the frequency interval Δf shown in FIG.

Therefore, in the first embodiment, the amplifier 105
A capacitor 107 (FIG. 1) is connected between the output 105b (FIG. 1) and the output 106b of the amplifier 106 (FIG. 1). Then, the capacitor 107 (FIG. 1) is provided with a characteristic that the impedance becomes low with respect to the frequency Δf. In other words, the self-resonant frequency of the capacitor 107 (FIG. 1) is Δf
To As a result, the output 10 of the amplifier 105 (FIG. 1)
5b and the Δf component of the output 106b of the amplifier 106 (FIG. 1) can be mutually reduced. The reason will be described below.

Referring again to FIG. 1, the two balanced outputs 105b and 106 of push-pull amplifiers 105 and 106
In b, each Δf component has the same amplitude and the same phase. As described above, in the present embodiment, the capacitor 107 having a low impedance with respect to the frequency Δf is provided. The capacitor 107 transmits the Δf component substantially as it is. Here, paying attention to the output 105b of the amplifier 105, the Δf component is output, and the Δf component having the same amplitude and the same phase transmitted from the output 106b of the amplifier 106 is input. The opposite is true at the output 106b of the amplifier 106. At outputs 105b and 106b, theoretically, Δf
The components do not cancel each other.

However, in practice, the wiring of the circuit contains an impedance component and a phase shift of the Δf component occurs, so that the Δf component is partially canceled and reduced. Thereby, the frequency Δf component and the signal frequency (f1 or f
2) The occurrence of mixing with components can be eliminated,
Third-order intermodulation distortion generated in the amplifier can be reduced. In addition, the number of parts can be reduced as compared with the related art. In addition, since it is not necessary to use two capacitors having the same characteristics, there is an excellent effect that it is not necessary to consider deterioration of characteristics due to individual differences of the capacitors. As described above, according to the first embodiment, a power amplifier with reduced intermodulation distortion and reduced number of components can be realized.

In the first embodiment, the input signals are two sine wave signals of frequencies f1 and f2. However, the two sides of the component curve of the modulated wave shown in FIG.
If 1, f2, the same effect can be obtained for the modulated wave.

In the first embodiment, the capacitor 10
7 (FIG. 1) was connected to the output side of output side matching circuits 115 and 116. However, a similar effect can be obtained even if the configuration is different from this configuration. FIG. 7 shows a power amplifier 100.
FIG. 6 is a circuit diagram according to another example of FIG. The power amplifier 100 is provided on the amplification element side of the output side matching circuits 115 and 116, that is, the output side matching circuits 115 and 116 and the amplification elements 111 and 11.
2 may be connected to the drain terminal. The capacitor 107 is connected to the first amplification path 161 and the second amplification path 162
It is only necessary to be connected between them.

Next, a configuration for further reducing the Δf component will be described. FIG. 8 is a block diagram showing a configuration of power amplifier 110 that reduces the Δf component. Hereinafter, only the components of the power amplifier 110 different from the power amplifier 100 (FIG. 3) will be described, and the description of the same components will be omitted.

Power amplifier 110 differs from power amplifier 100 (FIG. 3) in that phase shifter 8 is connected in series with capacitor 107.
1 is provided. The phase shifter 81 can change the phase of the input signal. Specifically, the phase shifter 81 outputs the input signal of the Δf component output from the amplifier 105 in a phase opposite to that of the signal of the Δf component output from the amplifier 106. In addition, for the input signal of the Δf component output from the amplifier 106, the phase shifter 81
And outputs a signal having a phase opposite to the phase of the signal of the Δf component output from. That is, the Δf components have almost the same phase with the same amplitude, and the output 105 b of the amplifier 105 also
Also at the output 106b of 06, it is reduced. As a result, the third-order intermodulation distortion generated in the amplifier can be significantly reduced. Further, by changing the phase in consideration of the phase shift due to the impedance of the circuit wiring, the Δf component can be canceled so as to become substantially zero.

The phase shifter 81 may be provided in series with the capacitor 107 described with reference to FIG. 7, or provided so as to connect between the output of the amplifier 105 and the output of the amplifier 106 in FIG. Is also good.

(Second Embodiment) FIG. 9 is a circuit diagram of a power amplifier 100 according to a second embodiment. The same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The power amplifier 100 shown in FIG. 9 differs from the power amplifier according to the first embodiment only between the outputs of amplifiers 105 and 106, in other words, only between the first input and the second input of balun 104. Instead, a capacitor is connected between the drains of the amplification elements 111 and 112. A capacitor between the drains of the amplifying elements 111 and 112 is denoted by 107a, and a capacitor between the inputs of the balun 104 is denoted by 107b.

Generally, an actual capacitor has a unique self-resonant frequency, and the impedance at that frequency is close to 0Ω. For this reason, the capacitor 107b
Is provided, it is possible to reduce the intermodulation distortion due to the Δf component corresponding to the self-resonant frequency of the capacitor. However, the impedance becomes higher at a frequency apart from the self-resonant frequency. FIG.
5 is a graph illustrating an example of a resonance characteristic of a capacitor. FIG.
(A), the frequency band of the capacitor that exhibits low impedance characteristics is generally narrow.

The frequency of the signal input to the power amplifier is
It has a certain bandwidth, and the carrier signal of which frequency is used in the bandwidth varies depending on the case. Therefore,
The frequency interval Δf also has a predetermined width. As described above, since a capacitor generally has a narrow frequency band exhibiting low impedance characteristics, if the value of the frequency interval Δf is different from the self-resonant frequency of the capacitor 107b (FIG. 9), the intermodulation distortion cannot be reduced. There is.

Therefore, it is necessary to reduce the intermodulation distortion even when the value of the signal frequency interval Δf changes. In the second embodiment, a capacitor 107a having a self-resonant frequency different from that of the capacitor 107b is further connected. The frequency band where the impedance of the capacitor 107a is small and the frequency band where the impedance of the capacitor 107b is small have an overlapping portion. Thereby, the intermodulation distortion corresponding to the wide frequency interval Δf can be reduced. That is, the intermodulation distortion can be reduced according to the change in the frequency interval Δf between the two input signals.
For example, as shown in FIG. 10B, a capacitor 107a having a self-resonant frequency of 5 MHz and a capacitor 107b having a self-resonant frequency of 20 MHz are provided. Thereby, the intermodulation distortion at the time of amplifying a plurality of signals can be reduced over the frequency interval Δf ranging from 5 MHz to 20 MHz.

In the second embodiment, as in the first embodiment, it is possible to realize a power amplifier with reduced intermodulation distortion while reducing the number of components as compared with the related art.

Further, in the second embodiment, one of the two capacitors is connected to the amplifying element 111 and the amplifying element 112.
And the other one is a matching circuit 11
5 and 116 were connected between the two inputs of the output balun 104. This point is not limited to the above, and both may be connected between the drain terminals of the push-pull amplifier. Or, output side balun 1
04 may be connected between the first input and the second input. In these cases, effects similar to those of the second embodiment can be obtained.

In the second embodiment, two types of capacitors having different self-resonant frequencies are used. However, three or more types of capacitors having different self-resonant frequencies may be used. Further, the connection position can be freely set as long as it is between the first amplification path 151 and the second amplification path 152.
In this case, the same effect as that of the second embodiment can be obtained.

Further, by providing the phase shifter described with reference to FIG. 8, the intermodulation distortion when a plurality of signals are amplified can be greatly reduced. The phase shifter may be provided at a position where a signal of the Δf component is transmitted via each capacitor. The number of phase shifters corresponding to the number of capacitors may be provided, or may be provided only for a specific capacitor.

(Embodiment 3) FIG. 11 shows Embodiment 3 of the present invention.
FIG. 1 is a circuit diagram of a power amplifier 100 according to the first embodiment. Embodiment 1
The same components as those described in the above are denoted by the same reference numerals, and description thereof will be omitted.

The power amplifier 100 shown in FIG. 11 differs from the power amplifier according to the first embodiment in that an inductor 108 is connected between the outputs of push-pull amplifiers 105 and 106 instead of a capacitor. The inductor 108 is also an impedance element.

The meaning of providing inductor 108 is the same as that of capacitor 107 in the first and second embodiments. In the third embodiment, a case where two signals of frequencies f1 and f2 are input to power amplifier 100 will be considered. It is assumed that the frequency interval Δf is sufficiently smaller than the signal frequency. further,
It is assumed that the inductor 108 has low impedance around the frequency Δf. At this time, Δ appears on the output 105b of the amplifier 105 and the output 106b of the amplifier 106.
The f component cancels out for the same reason as described in the first embodiment. As a result, the mixing between the Δf component and the signal frequency (f1 or f2) in the amplifier does not occur, and as in the case of the first embodiment, 3
Second-order intermodulation distortion can be reduced. Further, it is possible to realize a power amplifier with a reduced number of components as compared with the related art.

A further feature of inductor 108 is that it exhibits low impedance characteristics even at frequencies lower than frequency Δf. Thus, by connecting the inductor 108 between the outputs of the push-pull amplifier, the intermodulation distortion can be reduced even when the frequency interval Δf of a plurality of signals input to the amplifier changes.

In the third embodiment, the inductor 108 is used as an impedance element having a low impedance at the frequency Δf, but a configuration shown in FIG. 12 may be used instead.

FIG. 12 is a circuit diagram showing another example of power amplifier 100 according to the third embodiment. Power amplifier 100
Then, instead of inductor 108, inductor 109a connected between the outputs of the push-pull amplifier, low-pass filter 109, and capacitor 109b connected between output 105b of amplifier 105 and ground 109d
And the output 106b of the amplifier 106 and the ground 109e.
And a low-pass filter 109 constituted by a capacitor 109c connected between the two. Inductor 108
By using the low-pass filter 109 instead of the above, the bandwidth in which the impedance becomes low can be widened.

Needless to say, even with a low-pass filter having a configuration different from the above-described configuration, the same effect as that of the present embodiment can be obtained. Also,
As described with reference to FIG. 8 in the first embodiment, a phase shifter may be provided to more reliably reduce the frequency interval Δf.

(Embodiment 4) FIG. 13 shows Embodiment 4 of the present invention.
1 is a block diagram showing a configuration of a power amplifier 200 according to the first embodiment. Power amplifier 200 has the same function as the power amplifier described in the first to third embodiments. That is, when a plurality of signals having sufficiently small frequency intervals with respect to the signal frequency are input, the power amplifier 200 reduces intermodulation distortion (particularly, third-order intermodulation distortion) and causes a phase shift with respect to the input signal. Output amplified signal without

First, the configuration of the power amplifier 200 will be described. The power amplifier 200 has an input terminal 201 and an input 20.
3a, a first balun 203 having a first output 203b and a second output 203c, an amplifier 205 having an input 205a and an output 205b, an amplifier 206 having an input 206a and an output 206b, and an input 204a;
A second balun 204 having a first output 204b and a second output 204c, a first directional coupler 51, a second directional coupler 52, and an output terminal 202 are provided.

As the directional couplers 51 and 52, known directional couplers that couple only a signal propagating in a specific direction in a transmission line to a secondary line can be used. The degree of attenuation that a signal undergoes when passing through the directional coupler and entering the secondary line is called the degree of coupling and is expressed in decibels. The first directional coupler 51 of the power amplifier 200 is connected to the first terminal 25
1a, a second terminal 251b, a third terminal 251c, and a fourth terminal 251d. The second directional coupler 52 has a first terminal 252a, a second terminal 252b, a third terminal 252c, and a fourth terminal 252d.

The connection relation in the power amplifier 200 is as follows. An input terminal 201 is connected to an input 203a of the balun 203, and a first output 203 of the balun 203.
b and the second output 203c
And the input 206a of the amplifier 206. The output 205b of the amplifier 205 is connected to the first terminal 251a of the first directional coupler 251 and the output 206b of the amplifier 206 is connected to the second terminal 251a.
Is connected to the first terminal 252a.

The connection relationship of the directional coupler is as follows. With respect to the first directional coupler 251, the second terminal 251b is connected to the first input 204b of the balun 204. The third terminal 251c is connected to the second directional coupler 2
52 is connected to the fourth terminal 252d. Fourth terminal 2
51d is a third terminal 25 of the second directional coupler 252.
2c. On the other hand, the second terminal 252 b of the second directional coupler 252 is connected to the second input 20
4c. The third terminal 252c and the fourth terminal 252d are as described above.

Hereinafter, the first output 20 of the balun 203 will be described.
A path from 3b to the first input 204b of the balun 204 via the amplifier 205 and the first directional coupler 251 is referred to as a first amplification path 261. In addition, balun 20
3 through the amplifier 206 and the second directional coupler 252 from the second output 203c of the balun 204 to the second input 2 of the balun 204.
The path that reaches 04c is referred to as a second amplification path 262.

FIG. 14 shows a specific circuit configuration of the power amplifier 200. As is apparent from the figure, the power amplifier 20
The functions and configurations of the zero amplifiers 205 and 206 are the same as those of the amplifiers 105 and 106 (FIG. 7). Therefore, the description is omitted.

As described above, the basic functions of power amplifier 200 are the same as those of the first to third embodiments. The principle by which power amplifier 200 can reduce intermodulation distortion (particularly third-order intermodulation distortion) will be described below with reference to FIG.

FIG. 15 is a diagram showing the principle of reducing intermodulation distortion. To the input terminal 201, two signals having a frequency interval sufficiently smaller than the signal frequency are input. The frequencies of the two input signals are represented by f1 and f2, respectively.
(For example, f1 is 2000 MHz, f2 is 2010 MH
z). The frequency interval (| f1-f2 |) is defined as Δf. As described in the first embodiment, the object of the fourth embodiment is to reduce Δf in order to reduce intermodulation distortion, particularly third-order intermodulation distortion.

Therefore, in the fourth embodiment, for example, a directional coupler having a coupling degree of 3 dB with respect to the frequency Δf representing the frequency interval between two signals and hardly coupling with the signal frequency is used. That is, the first directional coupler 2
Only the Δf component is extracted from the third terminal 251c of the first directional coupler 51 and the third terminal 252c of the second directional coupler 252. Third terminal 251 of first directional coupler 251
c component is extracted from the second directional coupler 25
The signal is input to the second fourth terminal 252 d and is combined with the output of the amplifier 206. The output signal of amplifier 206 includes a Δf component. It should be noted that this Δf component and the fourth terminal 2
The Δf component input to 52d indicates that the phase is shifted. This is because the circuit wiring includes an impedance component, so that if the circuit wiring length is different, the amount of phase shift is also different. As a result, the Δf components cancel each other, and the Δf components are reduced. First directional coupler 2
Similarly, the Δf component included in the output signal of the amplifier 205 in the second directional coupler 2 has a phase shift.
The Δf component taken out from the third terminal 252c of 52 is canceled and reduced.

As described above, the .DELTA.f component generated in each amplifier constituting the push-pull amplifier is canceled out, so that the .DELTA.f component and the signal frequency (f1 or f1) are cancelled.
Mixing with 2) does not occur. Therefore, third-order intermodulation distortion generated in the amplifier can be reduced. In the fourth embodiment, the degree of coupling of the directional coupler is set to 3 dB. However, the effect of suppressing intermodulation distortion can be obtained even if the coupling degree is different.

Next, a configuration capable of further reducing the intermodulation distortion will be described. FIG. 16 is a block diagram showing another example of the power amplifier 200. In this example, as described in the first to third embodiments, the frequency Δ
One or more capacitors 207 having low impedance at f are added. By shifting the frequency at which the degree of coupling of the directional coupler increases and the self-resonant frequency of the capacitor, intermodulation distortion corresponding to a wider frequency interval Δf can be suppressed.

Further, instead of the capacitor 207, the frequency interval of two signals as described in the third embodiment is used.
One or more inductors having low impedance at the frequency Δf may be added. By shifting the frequency at which the degree of coupling of the directional coupler increases and the frequency at which the inductor has low impedance, intermodulation distortion can be suppressed over a wider frequency interval Δf. The connection position of the capacitor 207 and the inductor can be freely set as long as it is between the first amplification path 261 and the second amplification path 262.

Further, according to the power amplifier 200 shown in FIG. 17, the intermodulation distortion when a plurality of signals are amplified can be greatly reduced. FIG. 17 shows a power amplifier 210 provided with two phase shifters. The difference from the power amplifier 200 (FIG. 13) is that two phase shifters 171 are provided on the wiring between the first directional coupler 251 and the second directional coupler 252 for transmitting the signal of the Δf component. , 172 are provided. For the Δf component input signal output from the amplifier 205, the phase shifter 171 outputs the signal having a phase opposite to that of the Δf component signal output from the amplifier 206. Also, for the Δf component input signal output from amplifier 206, phase shifter 172 generates Δf component output from amplifier 205.
The phase of the component signal is inverted and output. This allows
The Δf component has almost the same phase with the same amplitude and is reduced.
Thereby, the third-order intermodulation distortion generated in the amplifier can be significantly reduced. Further, by changing the phase in consideration of the phase shift due to the impedance of the circuit wiring, Δ
It can be canceled so that the f component becomes substantially zero. Note that the phase shifter is ΔΔ
17 may be provided at a position where the signal of the f component is transmitted.
It is not limited to the position shown in FIG.

(Embodiment 5) FIG. 18 shows Embodiment 5 of the present invention.
1 is a block diagram showing a configuration of a power amplifier 220 according to the first embodiment. Power amplifier 220 has the same function as the power amplifier described in the first to fourth embodiments. That is, when a plurality of signals having sufficiently small frequency intervals with respect to the signal frequency are input, the power amplifier 220 reduces intermodulation distortion (particularly, third-order intermodulation distortion) and causes a phase shift with respect to the input signal. Output amplified signal without

The power amplifier 220 is connected to the power amplifier 110
The difference from FIG. 8 is that a first inductor 181, a phase shifter 182, and a second inductor 183 are connected in series between the outputs of the push-pull amplifiers 105 and 106. The configuration of power amplifier 220 is similar to the configuration of power amplifier 110 (FIG. 8).
Therefore, the same components as those already described are denoted by the same reference numerals, and description thereof will be omitted.

Each of the inductors 181 and 183 has a high impedance with respect to the frequency of the signal output from the amplifiers 105 and 106, and has a low impedance with respect to the frequency of the Δf component signal.
By connecting the inductors 181 and 183 between the outputs of the amplifier, the frequency interval Δ of a plurality of signals input to the amplifier can be obtained.
Even when f changes, the intermodulation distortion can be reduced. The inductor is, for example, a choke coil, and is shared with a bias line of a bias power supply 184 for applying a bias voltage.

For the Δf component input signal output from amplifier 105, phase shifter 182 outputs a signal having a phase opposite to that of the Δf component signal output from amplifier 106. Further, with respect to the Δf component input signal output from amplifier 106, phase shifter 182 outputs a signal having a phase opposite to that of the Δf component signal output from amplifier 105.
That is, the Δf components have substantially the same amplitude and opposite phases, and are mutually reduced. Thereby, the third-order intermodulation distortion generated in the amplifier can be significantly reduced. Further, by changing the phase in consideration of the phase shift due to the impedance of the circuit wiring, the Δf component can be canceled so as to become substantially zero.

Next, a power amplifier 230 using the above-described series connection of the first inductor 181, the phase shifter 182, and the second inductor 183 will be described with reference to FIG. Characteristics of the inductors 181 and 183, and
The operation of the phase shifter 182 is as described above.

The configuration of power amplifier 100 (FIG. 7) is similar to the configuration of power amplifier 230. FIG. 19 is a block diagram showing a configuration of power amplifier 230. Power amplifier 23
0 is different from the power amplifier 100 (FIG. 7) in that the first inductor 181,
The point is that the phase shifter 182 and the second inductor 183 are connected in series, and that a bias power supply 184 for applying a bias voltage is connected between the phase shifter 182 and the second inductor 183. Further, by providing the bias power supply 184, the matching circuits 131 to 1
34 can also be omitted.

With this configuration, the .DELTA.f component is reduced by the phase shifter having the same amplitude and almost the opposite phase, and the third-order intermodulation distortion caused by the .DELTA.f component can be greatly reduced.

(Embodiment 6) FIG. 20 shows Embodiment 6 of the present invention.
1 is a block diagram showing a configuration of a power amplifier 300 according to the first embodiment. The power amplifier 300 has an input terminal 301 and an input 30.
3a, a first balun 303 having a first output 303b and a second output 303c, first to fourth directional couplers 353 to 356, an input 305a and an output 305b, and amplify the input signal. Amplifier 305 and input 306a
And an output 306b, and an amplifier 30 for amplifying an input signal
6, a second balun 304 having an input 304a, a first output 304b, and a second output 304c, and an output terminal 302.

The connection relation in power amplifier 300 is as follows. The input terminal 301 is connected to the input 303a of the balun 303. First output 30 of balun 303
3b and the second output 303c are connected to a first terminal 353a of the first directional coupler 353 and a first terminal 354a of the second directional coupler 354, respectively. The second terminal 353b of the first directional coupler 353 is connected to the input 305a of the amplifier 305, and the second terminal 354b of the second directional coupler 354 is connected to the input 306a of the amplifier 306. . Output 305b of amplifier 305
Is connected to the first terminal 355a of the third directional coupler 355, and the output 306b of the amplifier 306 is connected to the first terminal 356a of the fourth directional coupler 356. The second terminal 355b of the third directional coupler 355 and the second terminal 356b of the fourth directional coupler 356 are connected to the first input 304b and the second input 304 of the balun 304.
c. The output 304a of the balun 304 is connected to the output terminal 302.

Further, the third terminal 355c of the third directional coupler 355 is connected to the fourth terminal 354d of the second directional coupler 354, and the third terminal 354d of the fourth directional coupler 356 is connected to the third terminal 355c. And the fourth terminal 353d of the first directional coupler 353 are connected.

Hereinafter, the first output 30 of the balun 303 will be described.
3b via the first directional coupler 353, the amplifier 305, and the third directional coupler 355
The path that reaches the input 304b of the first amplifier path 361
And Also, the second input 303 of the balun 304 is supplied from the second output 303 c of the balun 303 via the second directional coupler 354, the amplifier 306, and the fourth directional coupler 356.
A path that reaches the section 04c is referred to as a second amplification path 362.

FIG. 21 shows a specific circuit configuration of the power amplifier 300. The configuration of amplifiers 305 and 306 is the same as the configuration of amplifiers 105 and 106 described in the first embodiment. Therefore, the description is omitted. Power amplifier 3
The basic function of 00 is the same as that of the first embodiment. Amplifiers 305 and 306 function as push-pull amplifiers.

In the sixth embodiment, two frequencies f1 and f2
Consider a case where two signals are input to power amplifier 300. It is assumed that the frequency interval Δf is sufficiently smaller than the signal frequency. As described in the first embodiment, the sixth embodiment also aims to reduce Δf in order to reduce intermodulation distortion, particularly third-order intermodulation distortion.

Therefore, in the sixth embodiment, for example, a directional coupler that has a coupling degree of 3 dB with respect to the frequency Δf representing the frequency interval between two signals and hardly couples with the signal frequency is used. This will be described more specifically with reference to FIG. 20 again. First, the signal of the frequency Δf component generated by the nonlinearity of the amplifier 305 is supplied to the third directional coupler 3.
55 through a third terminal 355d of the second directional coupler 354, and the amplifier 3
06. Similarly, the signal of the frequency Δf component generated by the non-linearity of the amplifier 306 is taken out from the third terminal 356c of the fourth directional coupler 356, and
Through the fourth terminal 353 d of the directional coupler 353.

With this configuration, the amplifier 3
The Δf component of the same amplitude, which is out of phase with the Δf component generated by the nonlinearity of 05, is input to the amplifier 305. As a result, the Δf component generated in the amplifier 305 is reduced. Further, a Δf component having the same amplitude and a phase shifted from the Δf component generated due to the nonlinearity of the amplifier 306 is input to the amplifier 306.
06, the Δf component generated is reduced. As a result, mixing between the Δf component and the signal frequencies (f1 and f2) does not occur, and the third-order intermodulation distortion generated in the amplifiers 305 and 306 can be reduced.

Although the degree of coupling of the directional coupler is set to 3 dB in the sixth embodiment, the effect of suppressing intermodulation distortion can be obtained even if the coupling degree is different.

As shown in FIG. 22, between the first amplification path 361 and the second amplification path 362, at least one capacitor 307 having a low impedance at the frequency Δf, which is the frequency interval between two signals, is provided. The above can also be added. Further, a capacitor 307 (FIG. 19)
Alternatively, at least one or more inductors (not shown) having a low impedance at a frequency Δf, which is a frequency interval between two signals, may be added. By shifting the frequency at which the degree of coupling of the directional coupler increases and the self-resonant frequency of the capacitor, or by shifting the frequency at which the degree of coupling of the directional coupler increases and the frequency at which the inductor has low impedance, a wider range is achieved. Intermodulation distortion can be suppressed for Δf.

The position where the capacitor 307 or the inductor (not shown) is connected is located at the first amplification path 3
The distance can be set freely between 61 and the second amplification path 362. Needless to say, the same effect as in the case of the present embodiment can be obtained in this case.

Embodiment 7 Next, another example to which the present invention can be applied will be described with reference to FIGS. Each of the examples aims to reduce a signal having a frequency Δf, which is a frequency interval between two input signals, which causes third-order intermodulation distortion.

FIG. 23 is a block diagram showing a configuration of a first power amplifier 400 according to the seventh embodiment. Power amplifier 400 is the same as power amplifier 300 described in the sixth embodiment.
It is a modification of (FIG. 20). Hereinafter, only components different from power amplifier 300 (FIG. 20) in power amplifier 400 will be described, and description of the same components will be omitted.

The power amplifier 400 is different from the power amplifier 300 (FIG. 20) in that the phase from the fourth directional coupler 356 transmitting the signal of the Δf component to the first directional coupler 353 is different. Device 371 and the third
The phase shifter 372 is provided on the wiring from the directional coupler 355 to the second directional coupler 354. The phase shifters 371 and 372 can change the phase of the input signal. Specifically, the phase shifter 371 reverses the phase of the signal of the Δf component output from the amplifier 306 with respect to the signal of the Δf component output from the amplifier 305, and outputs the signal.
Also, for the Δf component input signal output from amplifier 306, phase shifter 372 reverses the phase of the Δf component signal output from amplifier 305 and outputs the signal. As a result, the Δf component has the same amplitude and almost the opposite phase to the Δf component generated by the amplifiers 305 and 306, and reduces the Δf component generated by the amplifiers 305 and 306. Thereby, the third-order intermodulation distortion generated in the amplifier can be significantly reduced. Further, by changing the phase in consideration of the phase shift due to the impedance of the circuit wiring, the Δf component can be canceled so as to become substantially zero.

FIG. 24 is a block diagram showing a configuration of the second power amplifier 410 according to the seventh embodiment. Power amplifier 410 is a modification of power amplifier 400 (FIG. 23) described above. Hereinafter, the power amplifier 410 is
Only the components different from those in FIG. 23 will be described, and the description of the same components will be omitted.

Power amplifier 410 differs from power amplifier 400 (FIG. 23) in that inductors 413 to 416 are provided instead of directional couplers 353 to 356. The inductors 413 to 416 are, for example, choke coils and have low impedance at the frequency Δf. Thereby, also in the power amplifier 410,
The Δf component is extracted and reduced similarly to the power amplifier 400 (FIG. 23). Thereby, the third-order intermodulation distortion generated in the amplifier can be significantly reduced. Further, by changing the phase in consideration of the phase shift due to the impedance of the circuit wiring, the Δf component can be canceled so as to become substantially zero.

FIG. 25 is a block diagram showing a configuration of third power amplifier 420 according to the seventh embodiment. Power amplifier 420 is a modification of power amplifier 300 (FIG. 22). Hereinafter, the power amplifier 420 is replaced with the power amplifier 300 (FIG. 2).
Only the components different from 3) will be described, and description of the same components will be omitted.

The power amplifier 420 differs from the power amplifier 300 (FIG. 22) in that diplexers 421 and 422 are provided instead of the directional couplers 353 to 356. The diplexers 421 and 422 separate signals according to the frequency. More specifically, the diplexer 421,
422 is a fundamental wave component of the frequencies f1 and f2,
04, and the difference frequency component of the frequency Δf is passed through the amplifiers 305 and 306 on the opposite path.

The diplexers 421 and 422 operate at frequencies f
Band pass filters (BPF) 425 and 427 including passbands 1 and f2 (for example, GHz band);
(E.g., MHz band) in the pass band and low-pass filters (low-pass filters (LPF)) 426, 428 that do not include the frequencies f1, f2. The low-pass filters (LPF) 426 and 428 can be said to be impedance elements like the capacitor 107 (FIG. 1), the inductor 108 (FIG. 11), and the like.

An output signal from the amplifier 306 is input to the diplexer 422. The diplexer 422 allows the bandpass filter 427 to pass the fundamental wave components of the frequencies f1 and f2 through the balun 304,
The difference frequency component of the frequency Δf is output to the amplifier 305 by 28. It should be noted that the phase of the signal that has passed through the low-pass filter 428 gives a predetermined shift to the phase of the input signal. If this deviation is designed to be, for example, about 180 degrees, the Δf component input to the amplifier 305 has the same amplitude and almost the opposite phase to the Δf component generated by the amplifier 305. Thus, the Δf component generated in the amplifier 305 can be reduced. The function of the diplexer 421 is the same as that of the diplexer 422. That is, the bandpass filter 425 passes the fundamental wave components of the frequencies f1 and f2 to the balun 304, and the lowpass filter 426 outputs the difference frequency component of the frequency Δf to the amplifier 306. And the amplifier 30
6, the Δf component generated by the amplifier 306
Reduce the f component. As a result, the third-order intermodulation distortion generated in the amplifier can be significantly reduced.

FIG. 26 is a block diagram showing a configuration of fourth power amplifier 430 according to the seventh embodiment. Power amplifier 430 is a modification of power amplifier 420 shown in FIG. Power amplifier 430 is replaced by power amplifier 420 (FIG. 25).
The difference is that the Δf component is not reduced by the amplifiers 305 and 306, but is performed between the outputs of the diplexers 421 and 422. Also, the phase shifter 43
Since the phase of the Δf component is adjusted according to 1, the phase characteristic of the low-pass filter included in the diplexer does not have to be a particular problem.

More specifically, the Δf component generated by the amplifier 306 is extracted by the low-pass filter 428 and input to the phase shifter 431. The phase shifter 431 is
The phase of the input Δf component is adjusted so that the phase is opposite to the Δf component input to the diplexer 422, and output to the low-pass filter 426. Low-pass filter 426
Passes a Δf component whose phase is shifted by 180 degrees.
On the other hand, amplifier 305 also generates Δ
An amplified signal including the f component is input. As a result, the Δf component generated by the amplifier 305 is the Δf component received from the phase shifter.
It is reduced by the f component. This is the diplexer 42
1, the diplexer 422 also performs a process of simultaneously reducing the Δf component. In this process, since the diplexer 421 and the diplexer 422 may be replaced in the above description, the description is omitted. By the above processing, the Δf component is reduced and 3
Signals in which the next-order intermodulation distortion is significantly reduced are input to the balun 304 from the band-pass filters 425 and 427.

FIG. 27 is a block diagram showing a configuration of fifth power amplifier 440 according to the seventh embodiment. The power amplifier 440 is characterized in that phase shifters 441 and 442 are provided at the outputs of the amplifiers 305 and 306, respectively.
That is, the two inputs 44 are electrically connected by the inductor 445. The phase shifters 441 and 442 are designed to shift the phase by 90 degrees. Further, it is assumed that the inductor 445 has a characteristic that the impedance becomes low with respect to a frequency Δf, which is a frequency interval between two input signals. The balun 444 has a function of amplifying and converting two input signals whose phases are shifted from each other by 180 ° into one signal and outputting the signal, and is the same as the balun 104 (FIG. 1). .

Power amplifier 440 thus configured
However, the principle of reducing the Δf component will be described. First, the phase of the Δf component generated by the amplifier 306 is shifted by 90 degrees in the phase shifter 442. The inductor 44 of the balun 444 becomes low impedance with respect to the frequency Δf.
After 5, the phase shifter 441 further shifts the phase by 90 degrees. Since the phase shifter 441 shifts the phase in the same direction as the direction shifted by the phase shifter 442, the phase shifter 441 generates the Δ
The phase of the f component is finally shifted by 180 degrees. Then, the Δf component is input to the amplifier 305,
The Δf component generated by the amplifier 305 is reduced. Note that also in the amplifier 306, the Δf component is simultaneously reduced by the same processing as the above-described processing. As a result, a signal in which the Δf component is reduced and the third-order intermodulation distortion is significantly reduced is input to the balun 444.

FIG. 28 is a block diagram showing a configuration of a sixth power amplifier 450 according to the seventh embodiment. A feature of the power amplifier 450 is that a power supply 451 for outputting a signal having a frequency Δf, which is a frequency interval between two input signals, is provided. The frequency Δf of the signal to be output depends on the amplifier 30
5 or 306. Alternatively, the signal on the input side may be detected and generated. The signal of the frequency Δf output from the power supply 451 is input to the middle point of the transformer-side port (the inductor 445) of the balun 444 via the inductor 452 having a low impedance with respect to the frequency Δf. The inductor 445 also has a characteristic of having a low impedance with respect to the frequency Δf. The signal of the frequency Δf is input from the inductor 445 to the amplifiers 305 and 306. Amplifier 305,
The signal of frequency Δf when input to 306 changes its phase by passing through inductors 452 and 445. As a result, the Δf component generated in the amplifiers 305 and 306 can be reduced. The power supply 451 outputs the signal of the frequency Δf when input to the amplifiers 305 and 306 so as to be shifted by 180 degrees from the phase of the generated Δf component in consideration of the phase shift caused by the inductors 452 and 445. The phase of the signal may be adjusted. As a result, the Δf component generated in the amplifiers 305 and 306 can be reduced more reliably.

The frequency Δf of the signal to be output is
In the case of extracting from the output terminal 05 or 306, the power supply 451 need not be provided. FIG. 29 shows Embodiment 7
FIG. 17 is a block diagram showing a configuration of a seventh power amplifier 460 according to the third embodiment. As is clear from the figure, the power supply 451 (FIG. 28)
Is omitted, and the output of the amplifier 306 is
, Is input to the middle point of the transformer-side port (inductor 445) of the balun 444.

When the frequency Δf of the signal to be output is generated by detecting the signal input from the input terminal 301, the configuration shown in FIG. 30 is effective. FIG. 30 is a block diagram showing a configuration of the eighth power amplifier 470 according to the seventh embodiment. The power amplifier 470 is characterized in that an envelope detection unit 471 is provided. Envelope detector 471
Performs envelope detection of a signal input from the input terminal 301 and performs a frequency Δf, which is a frequency interval between two input signals.
And outputs the signal.

[0116]

As described above, according to the present invention, when a plurality of signals are input to the push-pull amplifier, the component of the frequency interval Δf generated at the output terminal of the push-pull amplifier is reduced. As a result, the intermodulation distortion generated in the amplifier can be suppressed, and it is not necessary to provide a capacitor in the bias circuit unlike the related art, so that the number of components can be reduced. As a result, the linearity of the amplifier is improved, and a power amplifier capable of amplifying a large number of signal channels at once without distortion can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a power amplifier according to a first embodiment.

FIG. 2 shows a specific circuit configuration of a power amplifier.

FIG. 3 is a block diagram illustrating signal waveforms at various parts of the power amplifier.

FIG. 4A is a waveform diagram of signals of frequencies f1 and f2. (B) is a waveform diagram of a synthesized signal obtained by synthesizing signals of frequency f1 and frequency f2. (C) shows the first signal and the second signal converted and output by the balun.
FIG. 6 is a diagram showing a waveform of a signal of FIG.

FIG. 5A is a diagram showing a composite signal waveform input to each amplifier constituting a push-pull amplifier and a waveform of an ideal amplified signal. (B) is a diagram showing the waveform of the input composite signal and the waveform of the actual amplified signal.

FIG. 6 shows a spectrum distribution obtained by performing a component analysis on the signal waveform F ′ shown in FIG.

FIG. 7 is a circuit diagram showing another example of the power amplifier of FIG. 1;

FIG. 8 is a block diagram illustrating a configuration of a power amplifier that reduces a Δf component.

FIG. 9 is a circuit diagram of a power amplifier according to a second embodiment.

FIG. 10 is a graph showing an example of a resonance characteristic of a capacitor.

FIG. 11 is a circuit diagram of a power amplifier according to a third embodiment.

FIG. 12 is a circuit diagram showing another example of the power amplifier of FIG. 11;

FIG. 13 is a block diagram showing a configuration of a power amplifier according to a fourth embodiment.

FIG. 14 is a diagram illustrating a specific circuit configuration of a power amplifier.

FIG. 15 is a diagram illustrating the principle of reducing intermodulation distortion.

FIG. 16 is a block diagram showing another example of the power amplifier of FIG.

FIG. 17 is a diagram showing a power amplifier provided with two phase shifters.

FIG. 18 is a block diagram showing a configuration of a power amplifier according to a fifth embodiment.

FIG. 19 is a block diagram illustrating a configuration of a power amplifier.

FIG. 20 is a block diagram showing a configuration of a power amplifier according to a sixth embodiment.

FIG. 21 shows a specific circuit configuration of a power amplifier.

FIG. 22 is a block diagram showing another example of the power amplifier of FIG. 20.

FIG. 23 is a block diagram showing a configuration of a first power amplifier according to a seventh embodiment.

FIG. 24 is a block diagram showing a configuration of a second power amplifier according to a seventh embodiment.

FIG. 25 is a block diagram showing a configuration of a third power amplifier according to a seventh embodiment.

FIG. 26 is a block diagram showing a configuration of a fourth power amplifier according to the seventh embodiment.

FIG. 27 is a block diagram showing a configuration of a fifth power amplifier according to a seventh embodiment.

FIG. 28 is a block diagram showing a configuration of a sixth power amplifier according to the seventh embodiment.

FIG. 29 is a block diagram showing a configuration of a seventh power amplifier according to the seventh embodiment.

FIG. 30 is a block diagram showing a configuration of an eighth power amplifier according to the seventh embodiment.

FIG. 31 is a diagram showing a conventional power amplifier.

[Explanation of symbols]

 Reference Signs List 101 input terminal 102 output terminal 103, 104 balun 105, 106 amplifier 107 capacitor 161 first amplification path 162 second amplification path

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Miyaji 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Seiji Fujiwara 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama, Kanagawa Prefecture Matsushita F-term (reference) in Telecommunications Industry Co., Ltd. KA68 SA14 TA01 TA02 TA06 UW08

Claims (27)

[Claims] 1. An input unit for inputting a synthesized signal obtained by synthesizing two signals having different frequencies, a first output unit for outputting a first signal having a first phase, and an inverse of the first phase. A first balun having a second output unit for outputting a second signal having a second phase, and a frequency difference between the two signals by receiving and amplifying the first signal. First including frequency components
A first amplifier that outputs an amplified signal of the second signal, and a second amplifier that receives and amplifies the second signal and includes a frequency component that is a difference between the frequencies of the two signals.
A second amplifier for outputting an amplified signal, and a first input unit and a second input unit, and outputs a composite signal of the signals input from the first input unit and the second input unit. A second balun having an output unit; and a frequency component included in the second amplified signal,
The frequency component is reduced by inputting from a first output of the balun to a first amplification path reaching the first input of the second balun via the first amplifier. The first amplified signal having the reduced frequency component is input to a first input unit of the second balun, and the frequency component included in the first amplified signal is converted to the first amplified signal.
The frequency component is reduced by inputting from a second output of the balun to a second amplification path reaching the second input of the second balun via the second amplifier. A power amplifier for inputting the second amplified signal having the reduced frequency component to a second input of the second balun. 2. The power amplifier according to claim 1, wherein the frequency component is reduced when the phase of the frequency component included in the amplified signal is different from the phase of the input frequency component. 3. An apparatus further comprising an impedance element connected between the first amplification path and the second amplification path, the impedance element having a characteristic of passing the frequency component. And a frequency component included in the second amplified signal, and a frequency component included in the second amplified signal,
The power amplifier according to claim 2, wherein the power is input to the first amplification path. 4. The frequency component connected in series with the impedance element and included in the first amplified signal,
4. The power amplifier according to claim 3, further comprising a phase shifter that receives the frequency components included in the second amplified signal, adjusts the phase of each frequency component, and outputs the components in opposite phases. 5. A first directional coupler connected to the first amplification path and receiving the first amplification signal, and connected to the second amplification path and receiving the second amplification signal. A second directional coupler, wherein the first directional coupler extracts a frequency component of the first amplified signal and outputs the frequency component to the second directional coupler; Receiving the frequency component included in the second amplified signal from the directional coupler of the first to reduce the frequency component to generate a first amplified signal with the reduced frequency component; The directional coupler extracts a frequency component of the second amplified signal and outputs the extracted frequency component to the first directional coupler, and the directional coupler is included in the first amplified signal from the first directional coupler. By receiving the frequency component, the frequency component is reduced and the frequency Number component to produce a reduced second amplified signal, the power amplifier according to claim 1. 6. An output of said first directional coupler and a second
Is provided between the input of the directional coupler and receives the frequency component included in the first amplified signal, adjusts the phase of the frequency component, the frequency component included in the second amplified signal A first phase shifter that outputs an inverted phase; an output of the second directional coupler and an input of the first directional coupler, which are included in the second amplified signal A second phase shifter that receives the frequency component, adjusts the phase of the frequency component, and outputs the signal in an opposite phase to the frequency component included in the first amplified signal.
The power amplifier according to claim 5. 7. The power amplifier according to claim 5, wherein the first directional coupler and the second directional coupler have a coupling degree of at least 3 dB or more with respect to the frequency component. 8. A first directional coupler connected to the first amplification path, for extracting and outputting a frequency component of the first amplified signal, and connected to the second amplification path, A second directional coupler for extracting and outputting a frequency component of a second amplified signal, wherein the first amplifier is configured to output the second amplified signal from the second directional coupler. Receiving a frequency component included in the signal, the frequency component is reduced, and a first amplified signal having the reduced frequency component is generated. The second amplifier outputs the first amplified signal from the first directional coupler. The received frequency component included in the first amplified signal is reduced to generate a second amplified signal in which the frequency component is reduced and the frequency component is reduced.
A power amplifier according to claim 1. 9. The power amplifier according to claim 8, wherein the first directional coupler and the second directional coupler have a coupling degree of at least 3 dB or more with respect to the frequency component. 10. The power amplifier according to claim 3, wherein said impedance element is a capacitive element. 11. The power amplifier according to claim 3, wherein said impedance element is an inductive element. 12. The power amplifier according to claim 3, wherein said impedance element is a low-pass filter. 13. The power amplifier according to claim 3, comprising two or more impedance elements having different self-resonant frequencies. 14. The power amplifier according to claim 3, wherein the impedance element has a low impedance with respect to the frequency component. 15. The first impedance element according to claim 1, wherein
4. The power amplifier according to claim 3, wherein the power amplifier is connected between an output of the second amplifier and an output of the second amplifier. 16. The first amplifier, a first matching circuit for matching an input impedance of the first amplifier, a first amplifying element connected to an output of the first matching circuit, A second matching circuit that is connected to an output of the first amplifying element and that matches an impedance on an output side of the first amplifier. The second amplifier includes an input of the second amplifier. A third matching circuit that matches the impedance of the second amplifier, a second amplifier connected to the output of the third matching circuit, and a second amplifier connected to the output of the second amplifier. The power amplifier according to claim 1, further comprising: a fourth matching circuit that matches output-side impedance. 17. The method according to claim 17, wherein the impedance element includes the first element.
17. The power amplifier according to claim 16, wherein the power amplifier is connected between an output of the second amplification element and an output of the second amplification element. 18. The method according to claim 18, wherein the impedance element includes the first element.
17. The power amplifier according to claim 16, wherein the power amplifier is connected between an output of the amplifying element and an output of the fourth matching circuit. 19. The method according to claim 19, wherein the impedance element includes the second element.
17. The power amplifier according to claim 16, wherein the power amplifier is connected between an output of the matching circuit and an input of the fourth matching circuit. 20. A first impedance element connected to the first amplification path and having a characteristic of passing a frequency component of the first amplification signal, and a second impedance element connected to the second amplification path and connected to the second amplification path. And a second impedance element having a characteristic of passing a frequency component of the amplified signal of the first amplifier. The first amplifier converts a frequency component included in the second amplified signal through a second impedance element. By receiving the signal, the frequency component is reduced, and a first amplified signal having the reduced frequency component is generated. The second amplifier is configured to add the first amplified signal to the first amplified signal via a first impedance element. 2. The method according to claim 1, wherein receiving the included frequency component reduces the frequency component and generates a second amplified signal having the reduced frequency component.
A power amplifier according to claim 1. 21. The power amplifier according to claim 20, wherein said impedance element is a low-pass filter. 22. A signal processing apparatus which is provided between an output of the first amplifier and a first input section of the second balun, and outputs the input signal by shifting the phase of the input signal by 90 degrees in a predetermined direction. 1 phase shifter, an output of the second amplifier, and a second input unit of the second balun, the output of the input signal being shifted by 90 degrees in a predetermined direction. The second balun further includes an impedance element that connects the first input unit and the second input unit and has a characteristic of passing the frequency component. The power amplifier according to claim 1. 23. A first low-pass filter connected to the first amplification path and having a characteristic of passing a frequency component of the first amplification signal, and connected to the second amplification path, A second low-pass filter having a characteristic of passing a frequency component of a second amplified signal; and a first low-pass filter connected in series to the first low-pass filter and the second low-pass filter; Further provided with a phase shifter that receives the frequency component included in the amplified signal and the frequency component included in the second amplified signal, adjusts the phase of each frequency component, and outputs the phase components in opposite phases,
The power amplifier according to claim 1. 24. A power supply for outputting the signal of the frequency component in a phase opposite to that of the signal of the frequency component, wherein the second balun receives the signal output from the power supply, The power amplifier according to claim 1, wherein the power is input to the first amplification path and the second amplification path via the first input section and the second input section. 25. An impedance element connected to one of an output of the first amplifier and an output of the second amplifier, the impedance element having a characteristic of transmitting the frequency component. 2. The device according to claim 1, wherein the signal output from the element is received and input to the first amplification path and the second amplification path via the first input unit and the second input unit. 3. Power amplifier. 26. The apparatus according to claim 26, further comprising: a detection unit that performs envelope detection based on a combined signal input to an input unit of the first balun, extracts the frequency component, and outputs the extracted frequency component. Receiving the signal output from the detection unit, and inputting the signal to the first amplification path and the second amplification path via the first input unit and the second input unit. 2. The power amplifier according to 1. 27. A phase difference between the output of the first directional coupler and the input of a second amplifier, wherein the frequency component included in the first amplified signal is received and the phase of the frequency component is received. A first phase shifter that adjusts the phase of the second amplified signal and outputs a signal having an opposite phase to the frequency component included in the second amplified signal; A second component that receives the frequency component included in the second amplified signal, adjusts the phase of the frequency component, and outputs the signal in the opposite phase to the frequency component included in the first amplified signal. The power amplifier according to claim 8, further comprising a phase shifter.