JP4435071B2 - Power amplifier and amplification method - Google Patents

Description

  The present invention relates to a high-frequency high-efficiency power amplifier.

  In recent years, broadband (high-speed) communication in which modulation such as CDMA and OFDM is performed at a high frequency on the order of gigahertz has been performed. In these wireless communications, the power amplifier at the output stage must amplify a signal having a high peak power with respect to the average power, so that the saturation level of the power amplifier needs to be increased (back off). However, the efficiency of the amplifier decreases when it is used with a back-off from the saturation level.

One means for improving the efficiency is a method called load modulation. Load modulation is a method of maintaining high efficiency by increasing the apparent load of the power amplifier when the output level drops, and maintaining the voltage at the saturation voltage level. A typical example is a Doherty amplifier (for example, Patent Document 1). However, the Doherty amplifier has a problem that optimization of circuit design parameters is difficult, and a problem that the entire circuit becomes complicated.
JP 2004-289504 A (page 7, FIG. 1)

  The high-frequency amplifier with the back-off has a problem that the efficiency is lowered at the time of low output, and it is difficult to optimize circuit parameters for improving the efficiency, and the circuit becomes complicated.

  The present invention has been made to solve the above problems, and an object thereof is to provide a high-frequency high-efficiency power amplifier having a simple circuit configuration.

  In order to achieve the above object, a power amplifier according to the present invention is a high-frequency power amplifier, wherein a first hybrid that outputs an input signal in a system divided into two, and a signal of each system 2 are input. Two input terminals, a first output terminal that outputs the signals of each system in the same phase direction, and a reflection terminal are connected, and the signals of each system are added in the opposite phase direction and output. A second hybrid comprising a second output terminal, and a first hybrid connected between one output terminal of the first hybrid and one input terminal of the second hybrid. An amplifier, a second amplifier inserted and connected between the other output terminal of the first hybrid and the other input terminal of the second hybrid, each having a control input terminal, 1 amplifier input or The first variable phase shifter connected to the output and the second variable phase shifter connected to the input or output of the second amplifier and the level of the input signal are observed, and the input corresponding to the level Control means for outputting a phase control signal that gives a larger phase change as the level is lower to the control input terminal of each of the variable phase shifters with a reverse polarity.

  The power amplifier amplification method of the present invention is a high frequency power amplifier amplification method, wherein the power amplifier includes first and second hybrids, first and second amplifiers, first and second amplifiers. 2 variable phase shifters and control means, wherein the first hybrid outputs the input signal as a system divided into two, and the signals of one system are the first variable phase shifter and the first The second hybrid signal is input to one input terminal of the second hybrid via an amplifier of the second hybrid, and the signal of the other hybrid is input to the second hybrid via the second variable phase shifter and the second amplifier. The second hybrid is inputted to the other input terminal, and the second hybrid adds and outputs the signals of the inputted systems in the same phase direction, the second output terminal is connected to a reflection terminal, and Add the system signals in the opposite phase direction The control means observes the level of the input signal of the first hybrid and applies a phase control signal that gives a larger phase change to the control input terminal of each of the variable phase shifters with a reverse polarity. It is characterized by outputting.

  According to the present invention, a high-efficiency power amplifier having a simple circuit configuration and high frequency can be provided.

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

FIG. 1 is a block diagram showing a functional configuration of a high-efficiency power amplifier (hereinafter referred to as a high-efficiency amplifier) according to an embodiment of the present invention.
In FIG. 1, a high-efficiency amplifier includes a high-frequency signal input terminal I, an output terminal O, a level detector 1, a controller 2, a 90 ° hybrid 3a, variable phase shifters 4a and 4b, a 90 ° phase shifter 5a, 5b, amplifiers 6a and 6b, and a 90 ° hybrid 3b to which a reflection terminal R is connected.

  Hereinafter, the function and operation of each component of the high efficiency amplifier will be described with reference to FIG.

  The signal input to the input terminal I is guided to one input terminal of the hybrid 3a. In the hybrid 3a, the input signal is input from one output terminal to the variable phase shifter 4a, and from the other output terminal to the other variable phase shifter 4b via the 90 ° phase shifter 5a. . The other input terminal of the hybrid 3a is input-terminated by a resistor or the like.

  Further, the signal level of the signal input to the hybrid 3 a is measured by the level detector, and the measurement result is output to the controller 2. The controller 2 generates a control signal that gives a preset phase change from the input signal level data and outputs the control signal to the variable phase shifters 4a and 4b.

  This control signal has a reverse polarity, and causes a phase change (+ φ, −φ) in the reverse direction by the variable phase shifters 4a and 4b. The amount of phase change increases as the input level decreases, and is minimum or zero at the maximum output of the high efficiency amplifier.

  The outputs of the variable phase shifters 4a and 4b are further output to the amplifiers 6a and 6b, respectively. The output of one amplifier 6a is input to one input terminal of the hybrid 3b via a 90 ° phase shifter 5b. The output of the other amplifier 6b is input to the other input terminal of the hybrid 3b.

  As a result, the signal input to the hybrid 3a is output to the output terminal O in phase from one of the outputs of the hybrid 3b via the divided amplifiers 6a and 6b. In addition, a reverse-phase output is output from the other output of the hybrid 3b to the reflection terminal R.

FIG. 2 is a waveform diagram of a signal output from the hybrid 3b to the reflection terminal R.
If there is no phase change in the variable phase shifters 4a and 4b, nothing is output to the reflection terminal R as shown in FIG. On the other hand, if there is a phase change, as shown in FIG. 2B, a signal component that is not canceled out in the opposite phase is output to the reflection terminal R, and the reflected signal returns to the amplifiers 6a and 6b.

  If there is a reflected signal and its phase is appropriately adjusted, the load seen from the amplifiers 6a and 6b will appear to be the same as when a high load is connected, and behave as if the power efficiency is increased.

  Therefore, if the controller 2 outputs the phase control signal to the variable phase shifters 4a and 4b so that the phase change is large when the input level is small and the phase change is small when the input level is large, the high efficiency amplifier can be obtained. Can be built.

  At the time of input at which the rated maximum output is obtained, the controller 2 outputs a control signal so that there is no phase change in the variable phase shifters 4a and 4b. On the other hand, when the input is reduced by Adb, a control signal for giving a phase change (φ = ± β °) to the variable phase shifters 4a and 4b is output. Then, if the phase difference at the reflection terminal R of the hybrid 3b is set to a difference of 2 × β °, a reflected signal of a component that is not canceled out in the opposite phase is generated.

  As a result, when the output decreases, the apparent load increases due to the generated reflected signal, and the amplifiers 6a and 6b operate so that the output voltage maintains the saturation voltage. As a result, it is possible to prevent the efficiency from being deteriorated even when the output is reduced as compared with the rating as compared with the case where there is no reflected signal.

  The relationship between the decrease in the output of the amplifiers 6a and 6b and the decrease in efficiency is not linear, and the input level and efficiency often show an exponential change. In order to correct this, the controller 2 may generate and output a control signal from the level signal from the level detector 1 based on the nonlinearity between the applied voltage of the diode and the output voltage.

  Further, the relationship between the input level and the phase correction amount is tabulated in advance and stored in a memory (not shown) inside the controller 2, and a CPU (not shown) compares the contents of this memory with the input from the level detector 1 to obtain the phase. A correction control voltage may be output.

FIG. 3 is a block diagram showing another functional configuration example of the high efficiency amplifier according to the embodiment of the present invention.
In FIG. 3, the hybrid 3c and 3d are 180 ° type, and the 90 ° type phase shifters of the phase shifters 5a and 5b in FIG. 1 are omitted. In this method as well, as in the case of FIG. 1, a signal having a reverse phase is output to the reflection terminal R connected to the output-side hybrid 3d. Since the operation of the control unit 2 that controls the phase change with respect to the level of the input signal (output signal) is the same as that in FIG.

FIG. 4 is a functional block diagram showing a configuration of a high efficiency amplifier having both amplitude and phase distortion compensation.
In FIG. 4, the controller 2 in FIG. 1 replaces the controller 2a that further outputs the phase distortion compensation signal and the amplitude distortion compensation signal, and the input signal is input to the hybrid 3a via an ATT (variable attenuator) 2c. .

  A high-efficiency amplifier may be accompanied by amplitude and phase distortion due to its high efficiency, and may not be able to make full use of efficiency even though it has a back-off. Distortion improvement by a conventional feedback amplifier is incompatible with efficiency.

  Therefore, in the embodiment of the present invention, the non-linearity compensation with respect to the input signal level of the high efficiency amplifier is such that the controller 2a outputs a predetermined amplitude distortion compensation signal input from the level detector 1 to the ATT 2c. Done. Further, the phase distortion compensation signal for correcting the nonlinearity with respect to the input signal phase is input to the variable phase shifters 4a and 4b as a phase change value (ψ) with a bias having the same polarity.

  The high-efficiency amplifier shown in FIG. 4 has an effect of integrating a predistortion circuit for improving efficiency and compensating for distortion with the above-described two systems of amplifier circuits to make a small and easy circuit configuration. Note that the predistortion for compensating for the amplitude distortion and the phase distortion may correct both one of the amplitude distortion and the phase shift distortion even if both are not combined.

  In other words, when ATTc is omitted corresponding to the input level and amplitude distortion compensation is not performed, or a control signal for performing phase shift distortion compensation with the same polarity bias may not be output from the control unit 2.

  Note that the variable phase shifters 4a and 4b in FIGS. 1, 3, and 4 do not have to be located on the input side of the amplifiers 6a and 6b, but may be located on the output side. Further, as long as the amplifiers 6a and 6b include a phase adjusting unit, the control unit 2 may supply a phase control signal to the phase adjusting unit. Further, in FIG. 1 and FIG. 3, only one of the variable phase shifter 4a or the variable phase shifter 4b may be provided without providing two variable phase shifters.

  The positions of the 90 ° phase shifters 5a and 5b in FIGS. 1 and 4 may be located either before or after the amplifiers 6a and 6b.

  As described above, the high efficiency amplifier according to the present invention can provide a high efficiency high frequency amplifier with a simple circuit configuration.

The block diagram which shows the function structure of the high efficiency amplifier concerning the Example of this invention. The figure of the signal waveform output to a reflection termination from a hybrid. The block diagram which shows the other functional structure of the high efficiency amplifier concerning the Example of this invention. 1 is a functional block diagram showing a configuration of a high efficiency amplifier having both amplitude and phase distortion compensation according to an embodiment of the present invention.

Explanation of symbols

1 level detector 2 controller 3a, 3b, 3c, 3d hybrid 4a, 4b variable phase shifter 5a, 5b phase shifter (90 °)
6a, 6b Amplifier I Input terminal O Output terminal R Reflective termination

Claims (12)

A high-frequency power amplifier,
A first hybrid that outputs an input signal in a system divided into two;
Two input terminals to which signals of each system are input, a first output terminal to which signals of each system are added in the same phase direction and output, and a reflection terminal are connected, and signals of each system A second hybrid comprising a second output terminal that is added in the opposite phase direction and output.
A first amplifier inserted and connected between one output terminal of the first hybrid and one input terminal of the second hybrid;
A second amplifier inserted and connected between the other output terminal of the first hybrid and the other input terminal of the second hybrid;
A first variable phase shifter having a control input terminal and connected to an input or output of the first amplifier;
A second variable phase shifter having a control input terminal and connected to an input or output of the second amplifier;
Control means for observing the level of the input signal and outputting a phase control signal corresponding to the level and giving a larger phase change as the input level is lower to the control input terminal of each of the variable phase shifters. A characteristic power amplifier. A high-frequency power amplifier,
A 180 ° -type first hybrid that divides the input signal into two and outputs it;
Two input terminals to which signals of each system are input, a first output terminal to which signals of each system are added in the same phase direction and output, and a reflection terminal are connected, and signals of each system 180 ° type second hybrid provided with a second output terminal that is added in the opposite phase direction and output.
A first amplifier inserted and connected between one output terminal of the first hybrid and one input terminal of the second hybrid;
A second amplifier inserted and connected between the other output terminal of the first hybrid and the other input terminal of the second hybrid;
A first variable phase shifter having a control input terminal and connected to an input or output of the first amplifier;
A second variable phase shifter having a control input terminal and connected to an input or output of the second amplifier;
Control means for observing the level of the input signal and outputting a phase control signal corresponding to the level and giving a larger phase change as the input level is lower to the control input terminal of each of the variable phase shifters. A characteristic power amplifier. A high-frequency power amplifier,
A 90 ° -type first hybrid that divides an input signal into two parts and outputs it;
Two input terminals to which signals of each system are input, a first output terminal to which signals of each system are added in the same phase direction and output, and a reflection terminal are connected, and signals of each system 90 ° type second hybrid provided with a second output terminal that is added in the opposite phase direction and output.
A first 90 ° phase shifter and a first amplifier inserted and connected between one output terminal of the first hybrid and one input terminal of the second hybrid;
A second 90 ° phase shifter and a second amplifier inserted and connected between the other output terminal of the first hybrid and the other input terminal of the second hybrid;
A first variable phase shifter each having a control input terminal and connected to an input or output of the first amplifier;
A second variable phase shifter having a control input terminal and connected to an input or output of the second amplifier;
Control means for observing the level of the input signal and outputting a phase control signal corresponding to the level and giving a larger phase change as the input level is lower to the control input terminal of each of the variable phase shifters. A characteristic power amplifier.   4. The power amplifier according to claim 1, wherein the first or second variable phase shifter is omitted. The control means includes
In addition to the phase control signal transmitted to the first and second variable phase shifters, a second phase control signal for giving a phase bias of the same polarity is output to the first and second variable phase shifters. The power amplifier according to claim 1, wherein the power amplifier is a power amplifier. The input signal is further input to the input terminal of the first hybrid via a variable attenuator,
The control means observes the level of the input signal and outputs a control signal for adjusting an attenuation amount of the variable attenuator to a control terminal of the variable attenuator according to the level. The power amplifier according to any one of 2 and 3. A method for amplifying a high-frequency power amplifier,
The power amplifier is
First and second hybrids, first and second amplifiers, first and second variable phase shifters, and control means,
The first hybrid is:
An input signal is divided into two and output, and the signal of one system is input to one input terminal of the second hybrid via the first variable phase shifter and the first amplifier, The signal of the other system is input to the other input terminal of the second hybrid via the second variable phase shifter and the second amplifier,
The second hybrid is:
The input signals of each system are added in the same phase direction and output, and the second output terminal is connected to the reflection terminal, and the signals of each system are added in the opposite phase direction and output,
The control means includes
The power is characterized in that the level of the input signal of the first hybrid is observed, and a phase control signal that gives a larger phase change as the level is lower is output to the control input terminal of each variable phase shifter with a reverse polarity. Amplifier amplification method. A method for amplifying a high-frequency power amplifier,
The power amplifier is
Each of the 180 ° type first and second hybrids, first and second amplifiers, first and second variable phase shifters, and control means,
The first hybrid is:
An input signal is divided into two and output, and the signal of one system is input to one input terminal of the second hybrid via the first variable phase shifter and the first amplifier, The signal of the other system is input to the other input terminal of the second hybrid via the second variable phase shifter and the second amplifier,
The second hybrid is:
The input signals of each system are added in the same phase direction and output, and the second output terminal is connected to the reflection terminal, and the signals of each system are added in the opposite phase direction and output,
The control means includes
The power is characterized in that the level of the input signal of the first hybrid is observed, and a phase control signal that gives a larger phase change as the level is lower is output to the control input terminal of each variable phase shifter with a reverse polarity. Amplifier amplification method. A method for amplifying a high-frequency power amplifier,
The power amplifier is
First and second hybrids of 90 ° type, first and second amplifiers, first and second variable phase shifters, first and second 90 ° type phase shifters, and control means And
The first hybrid is:
An input signal is output in a system divided into two, and the signal of one system is output from the second variable phase shifter, the first 90 ° type phase shifter, and the first amplifier. The signal of the other system is input to the second input via the second variable phase shifter, the second 90 ° phase shifter, and the second amplifier. Input to the other input terminal of the hybrid
The second hybrid is:
The input signals of each system are added in the same phase direction and output, and the second output terminal is connected to the reflection terminal, and the signals of each system are added in the opposite phase direction and output,
The control means includes
The power is characterized in that the level of the input signal of the first hybrid is observed, and a phase control signal that gives a larger phase change as the level is lower is output to the control input terminal of each variable phase shifter with a reverse polarity. Amplifier amplification method.   10. The method of amplifying a power amplifier according to claim 7, wherein the first or second variable phase shifter is omitted. The control means includes
In addition to the phase control signal transmitted to the first and second variable phase shifters, a second phase control signal for giving a phase bias of the same polarity is output to the first and second variable phase shifters. The method for amplifying a power amplifier according to any one of claims 7, 8, and 9. The input signal is further input to the input terminal of the first hybrid via a variable attenuator,
The control means observes the level of the input signal and outputs a control signal for adjusting the attenuation amount of the variable attenuator to the control terminal of the variable attenuator according to the level. 10. A method for amplifying a power amplifier according to any one of claims 8 and 9.

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