JP2005204208A - Amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high efficiency in an amplifier which amplifies a fundamental wave signal to be amplified using an active element 3. <P>SOLUTION: The amplifier comprises: odd-order harmonics signal generation circuits A1-AN for generating odd-order harmonics signals relative to a fundamental wave signal to be amplified; rectangular wave signal generation circuits B1-BN, 1 for generating rectangular wave signals by composing the odd-order higher harmonic wave signals generated by the odd-order harmonics signal generation circuits A1-AN with the fundamental wave signal to be amplified; an active element 3 for amplifying the rectangular wave signals generated by the rectangular wave signal generation circuits B1-BN, 1; and an impedance matching circuit 4 which makes infinite a value of impedance for the odd-order higher harmonic wave signals if a load side is watched from an output terminal of the active element 3, and makes into zero a value of impedance for even-order higher harmonic wave signals. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to, for example, a non-linear power amplifier that amplifies a high-frequency signal, and more particularly to a technique for realizing high efficiency.

Conventionally, in order to increase the efficiency of a power amplifier, for example, a class C amplifier or a switching amplifier of class D, class E, class F, class S or the like has been used as a nonlinear amplifier.
As an example, FIG. 3 shows a configuration example of a class C power amplifier.
The power amplifier of this example includes an input matching circuit 11 to which an input terminal and a gate-source voltage (-Vgs) terminal that is a reverse bias are connected, and a transistor (Transistor) such as a field effect transistor (FET). And an output matching circuit 13 to which an output terminal and a drain-source voltage (Vds) terminal are connected are connected in series. As described above, in the class C amplifier, high efficiency is achieved by applying a reverse bias to the input side and placing the operating point of the active element 12 in a non-linear region.

  In order to realize a highly efficient operation, a conventional power amplifier has been provided with a matching circuit that takes into account the impedance of a high-frequency signal to be amplified and its harmonic signal. In the power amplifier, for example, when the load side is viewed at the output end of the amplifying element which is an active element, the impedance is set to zero for the even-order harmonic signal and the odd-order harmonic signal. On the other hand, by making the impedance infinite, the drain efficiency of the element can be ideally made 100% (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 5-29851

However, in the class C amplifier, when the theoretical power efficiency is 100%, the flow angle of the output current waveform of the active element 12 is 0 degree (°). As a result, power can be supplied to the load. There is a disadvantage that it can not.
The present invention has been made in view of such a conventional situation, and an object of the present invention is to provide an amplifier capable of realizing high efficiency in, for example, a nonlinear power amplifier that amplifies a high-frequency signal. .

In order to achieve the above object, in the amplifier according to the present invention, the fundamental wave signal to be amplified is amplified by the active element with the following configuration.
That is, the odd-order harmonic signal generation circuit generates an odd-order harmonic signal for the fundamental wave signal to be amplified, and the rectangular-wave signal generation circuit generates an odd-order harmonic signal generated by the odd-order harmonic signal generation circuit. The signal is combined with the fundamental wave signal to be amplified to generate a rectangular wave signal, and the active element amplifies the rectangular wave signal generated by the rectangular wave signal generation circuit. Further, when the impedance adjustment circuit looks at the load side from the output terminal of the active element, the impedance value for the odd-order harmonic signal is infinite and the impedance value for the even-order harmonic signal is zero. .
Therefore, for example, it is possible to supply the maximum power to the load even when the theoretical power efficiency is 100% as compared with the class C amplifier. High efficiency can be realized in a power amplifier or the like.

Here, various signals may be used as the fundamental wave signal.
Moreover, various frequencies may be used as the frequency of the fundamental wave signal, for example, a high frequency is used.
Various rectangular shapes may be used as the waveform of the rectangular wave signal.
Various active elements may be used. For example, an amplifying element composed of a transistor such as a field effect transistor (FET) is used. As an example, a power amplifier is used. As an example, a non-linear one for high frequency is used.
In addition, the odd-order harmonic signal generated by the odd-order harmonic signal generation circuit includes, for example, third-order, fifth-order, seventh-order,... Harmonic signals. Alternatively, harmonic signals from the 3rd order to the {(2N + 1)} th order which is the upper limit value may be used.
The rectangular wave signal generation circuit includes, for example, an odd-order harmonic signal control circuit that controls one or both of the amplitude and phase of an odd-order harmonic signal generated by the odd-order harmonic signal generation circuit, and an odd-order harmonic signal control circuit. It is configured using a synthesis circuit that synthesizes an odd-order harmonic signal controlled by a harmonic signal control circuit and a fundamental wave signal to be amplified.
Various circuits may be used as the impedance adjustment circuit.
The present invention is configured as a wireless or wired transmission amplifier, for example. Note that the present invention may be applied to various communication systems and communication devices.
Further, the present invention is configured, for example, by performing bias control for class B operation.

  As described above, according to the amplifier of the present invention, an odd-order harmonic signal is generated for the fundamental wave signal to be amplified, and the odd-order harmonic signal is combined with the fundamental wave signal to be amplified. The rectangular wave signal is amplified by the active element, and the impedance value for the odd-order harmonic signal when the load side is viewed from the output end of the active element is infinite and even. Since the impedance value for the next harmonic signal is set to zero, high efficiency can be realized in, for example, a non-linear power amplifier that amplifies a high-frequency signal.

An embodiment according to the present invention will be described with reference to the drawings.
FIG. 1A shows a configuration example of a power amplifier according to an embodiment of the present invention. The power amplifier of this example is a transmission amplifier that amplifies a high-frequency transmission wave signal, and is a nonlinear amplifier. In addition, the power amplifier of this example performs bias application in class B, unlike class C operation, for example.
As shown in FIG. 1A, the power amplifier of this example includes an input terminal (Input), a combiner 1, an input-side matching circuit (input matching circuit) 2, a field effect transistor (FET), and the like. The active element 3 composed of the above transistors, the λ / 4 long line 4, the tuning circuit 5, and the output terminal (Output) are connected in series. Further, a gate-source voltage (+ Vgs), which is a class B positive (+) bias, is applied to the input matching circuit 2, and a drain-source voltage (Vds) is applied to the λ / 4 long line. ing.
The power amplifier of this example includes one or a plurality of N harmonic generators A1 to AN and N controllers B1 to BN. Each harmonic generator A1 to AN is connected to the synthesizer 1 via each controller B1 to BN.

An example of the operation performed by the power amplifier of this example will be shown.
For example, a signal (fundamental wave signal) to be amplified having a high frequency f is input to the input terminal and input to the synthesizer 1.
Each harmonic generator Ai (i = 1, 2,..., N) generates a signal having a frequency (2i + 1) f and outputs it to each controller B1 to BN. Here, the signal output from each of the harmonic generators A1 to AN corresponds to an odd-order (that is, (2i + 1) -order) harmonic signal as viewed from the fundamental wave signal.
FIG. 1B illustrates an example of a fundamental wave signal having a frequency f, a third-order harmonic signal having a frequency 3f, and a fifth-order harmonic signal having a frequency 5f.
Each of the controllers B1 to BN has a function of changing one or both of the amplitude A and the phase φ of the signal input from each of the harmonic generators A1 to AN. 1 or when the change is unnecessary, the signals input from the harmonic generators A1 to AN are output to the synthesizer 1 as they are. Here, each of the controllers B1 to BN is configured using, for example, a fixed attenuator or a variable attenuator that changes the amplitude A of the signal, or a fixed phase shifter or a variable shifter that changes the phase φ of the signal. It is comprised using a phase shifter etc., or is comprised using both the said attenuator etc. and the said phase shifter.

The synthesizer 1 synthesizes the fundamental wave signal input from the input terminal and the odd-order harmonic signals input from the controllers B <b> 1 to BN, and outputs the resultant signal to the input matching circuit 2. Here, in this example, the signal generation state by each of the harmonic generators A1 to AN and the signal control by each of the controllers B1 to BN so that the combined signal output from the combiner 1 becomes a rectangular wave signal. The state is set or adjusted. When a square wave is expanded in a Fourier series, an input of an ideal rectangular wave is obtained by synthesizing a fundamental wave signal and a signal of an odd-order harmonic component such as the third or fifth order with respect to the fundamental wave signal. It can be seen that.
The input matching circuit 2 has a matching function, and outputs a rectangular wave signal input from the combiner 1 to the active element 3.
The active element 3 is an amplifying element in this example, and amplifies the rectangular wave signal input from the input matching circuit 2 and outputs the amplified signal to the λ / 4 long line 4. Here, in this example, since the input voltage waveform to the active element 3 is a rectangular wave, the active element 3 performs a switching operation.

The λ / 4 long line 4 is a 50 ohm (Ω) transmission line whose length is ¼ with respect to the wavelength λ of the fundamental wave signal (that is, the actual length is λ / 4). The signal input from the active element 3 is output to the tuning circuit 5. Here, by connecting such a λ / 4 long line 4 to the output end of the active element 3, the output end of the active element 3 (for example, when the active element 3 is an FET, between the drain and the source). ) When viewed from the load side, the impedance is infinite (∞) ohms (Ω) for signals of odd-order harmonic components, and the impedance is zero for signals of even-order harmonic components (0) Ohm (Ω) can be realized. As a result, the odd-order harmonic component signal is totally reflected to the output side of the active element 3, and the even-order harmonic component signal is attenuated, and an ideal switching operation is performed at the output of the active element 3. It can be performed.
The tuning circuit 5 is composed of, for example, a coil or a capacitor, has a function of selectively extracting a signal having a predetermined frequency component, and has a predetermined signal included in the signal input from the λ / 4 long line 4. The frequency component signal is extracted and output to the output terminal.

FIG. 2 shows an example of an output voltage waveform and an example of an output current waveform of the ideal active element 3 in this example.
As shown in the figure, in the output from the active element 3 of this example, when the voltage is applied, the current becomes zero, and when the current flows through the active element 3, the voltage becomes zero, that is, a non-zero voltage. The waveform and the non-zero current waveform do not overlap in time. In this way, the voltage becomes a rectangular wave composed of odd harmonic components, and the current becomes a half-wave rectified waveform signal composed of fundamental wave signals and even harmonic components, so that voltage and current do not exist simultaneously. Therefore, power consumption in the active element 3 is eliminated, and the efficiency is 100%.
Thus, in the power amplifier of this example, the power consumption in the active element 3 is 0 W, and the theoretical power efficiency is 100%. Here, unlike the class C amplifier, for example, the power amplifier of this example can supply power to the load even when the theoretical power efficiency is 100%.
In an actual circuit, there is an ON resistance (ON resistance) at the output terminal of the active element 3 (for example, between the drain and the source when the active element 3 is an FET). Is not 100%, and the voltage waveform of the output is not a perfect rectangular wave, so at this point there is a portion where the voltage waveform and current waveform overlap in time, and this portion consumes power. As a result, it can cause efficiency degradation. Although this is the case, the power amplifier of this example can achieve practically sufficient performance, and can improve power efficiency as compared with, for example, a class C amplifier.

As described above, in the power amplifier of this example, the harmonic generators A1 to AN that generate signals of odd-order harmonic components such as the third order and the fifth order with respect to the fundamental signal in the input stage, and the harmonics concerned. Controllers B1 to BN for controlling the signal of the wave component, a synthesizer 1 for synthesizing the signal of the harmonic component after the control and the fundamental wave signal, an active element 3 such as a transistor such as an FET, and the active element 3 Impedance conversion circuit (in this example, input matching circuit 2 and λ / 4 long line 4) and a filter circuit (in this example, tuning circuit 5) for extracting only necessary signal components. ), And only the fundamental wave signal and the odd-order harmonic component signal are input to the active element 3 and the voltage waveform input to the active element 3 is changed to a rectangular wave, thereby generating a high frequency signal. High efficiency of non-linear power amplifier There.
That is, in the power amplifier of this example, by providing a circuit for generating a rectangular wave on the input side, the active element 3 is switched, and the power supply voltage of the active element 3 is controlled, whereby the active element 3 The area where the voltage waveform and current waveform at the output of the output overlap in terms of time is reduced, and high efficiency is realized. Thereby, for example, even when the theoretical power efficiency is 100%, the maximum high frequency power can be supplied to the load, and the high efficiency of the high frequency nonlinear power amplifier can be realized.

Therefore, in the power amplifier of this example, an ideal rectangular wave can be realized by a circuit that generates an odd-order harmonic signal, for example, compared to a class F amplifier, thereby realizing an ideal switching operation. can do. Further, the power amplifier of this example can supply the maximum power to the load even when the theoretical power efficiency is 100% as compared with, for example, a class C amplifier. Improvements can be realized. In the power amplifier of this example, for example, most of the parameters that determine the power efficiency are determined only by the on-resistance of the active element 3, and the decrease in power efficiency due to other parameters is small.
In the power amplifier of this example, an odd-order harmonic signal generation circuit is configured by the circuits of the harmonic generators A1 to AN, and the circuits of the controllers B1 to BN constituting the odd-order harmonic signal control circuit A rectangular wave signal generation circuit is constituted by the circuit of the synthesizer 1 constituting the synthesis circuit, and an impedance adjustment circuit is constituted by the circuit of the λ / 4 long line 4. Further, the power amplifier of this example includes an input matching circuit 2 and a tuning circuit 5.

Here, the configuration of the amplifier or the like according to the present invention is not necessarily limited to the above-described configuration, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various devices and systems.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
The various processes performed in the amplifier according to the present invention are controlled by executing a control program stored in a ROM (Read Only Memory) by a processor using hardware resources including a processor and a memory, for example. For example, each functional unit for executing the processing may be configured as an independent hardware circuit.
Further, the present invention can also be grasped as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the above control program, or the program (itself). The processing according to the present invention can be performed by inputting a program from the recording medium to a computer and causing the processor to execute the program.

(A) is a figure which shows the structural example of the power amplifier which concerns on one Example of this invention, (B) is a figure which shows an example of a fundamental wave signal and an odd-order harmonic signal. It is a figure which shows an example of the waveform of the output voltage and output current of an ideal active element. It is a figure which shows the structural example of a class C power amplifier.

Explanation of symbols

  1 ·· Synthesizer, 2 · 11 ·· Input matching circuit 3 · 12 ·· Active element 4 ·· λ / 4 long line 5 ·· Tuning circuit 13 ·· Output matching circuit A1 to AN ·· Harmonic generator, B1-BN ... Controller

Claims (1)

In an amplifier that amplifies a fundamental wave signal to be amplified by an active element,
An odd-order harmonic signal generation circuit for generating an odd-order harmonic signal for the fundamental wave signal to be amplified;
A rectangular wave signal generating circuit for generating a rectangular wave signal by combining an odd harmonic signal generated by the odd harmonic signal generating circuit with a fundamental wave signal to be amplified;
An active element for amplifying the rectangular wave signal generated by the rectangular wave signal generation circuit;
An impedance adjustment circuit that makes the impedance value for the odd-order harmonic signal infinite when the load side is viewed from the output end of the active element and makes the impedance value for the even-order harmonic signal zero;
An amplifier comprising:

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