JP4652095B2 - Power amplifier - Google Patents

Description

  The present invention relates to a power amplifier used in microwaves and millimeter waves.

  Some conventional power amplifiers aim to improve the efficiency of the amplifier by suppressing the second harmonic (see, for example, Patent Document 1). This conventional power amplifier synthesizes the fundamental wave of the input signal with the same amplitude and the same phase between the input terminal and the output terminal, the power distribution circuit, the amplifier circuit, the 90-degree hybrid and the fundamental wave of the same amplitude and the same phase. The 90 ° hybrid is composed of a line having a quarter wavelength with respect to the fundamental wave.

  In the conventional power amplifier having the above configuration, the fundamental wave of the signal input to the input terminal is distributed with the same amplitude and the same phase by the power distribution circuit, amplified by the amplifier circuit, and output with the same amplitude and the same phase relationship. , 90-degree hybrid. When the fundamental wave is input to the 90-degree hybrid with the same amplitude and the same phase, a magnetic wall is formed on the symmetry plane, so the circuit between the input and output terminals is a fundamental wave connected in series with a 1/4 wavelength line, A fundamental wave connected in parallel is equivalent to a circuit composed of two open stubs of 1/8 wavelength. Therefore, the fundamental wave of the input signal is output with the same amplitude and the same phase, and is synthesized by the power synthesis circuit and outputted to the output terminal.

  On the other hand, the double wave generated by the amplifier circuit is input to the 90-degree hybrid with the same amplitude and the same phase. When a double wave is input with the same amplitude and the same phase, the circuit between the input and output terminals becomes parallel to a half wave line with a double wave connected in series. It becomes equivalent to a circuit composed of two open stubs of a quarter wave and a quarter wave connected, and eventually becomes equivalent to a circuit whose input terminal is short-circuited. Therefore, the second harmonic signal input to the 90-degree hybrid is completely reflected. Therefore, there is an effect that the efficiency of the amplifier is improved as compared with the case where the second harmonic wave is not completely reflected.

JP-A-11-112252

  By the way, it is known that even if the second harmonic is completely reflected, the efficiency is lowered depending on the phase condition. However, the conventional power amplifier has no function of changing the phase condition for the second harmonic. Further, the fundamental wave also has a problem that a loss occurs due to the parallel connection of the 1/8 wavelength open stubs as described above.

  The present invention has been made to solve the above-described problems, and completely reflects the second harmonic wave without affecting the fundamental wave, and easily changes the phase condition for the second harmonic wave to improve the efficiency. An object of the present invention is to realize a power amplifier that improves the above.

The power amplifier according to the present invention includes a power distribution circuit that distributes a fundamental wave of an input signal with the same amplitude and a phase difference of 180 degrees, two amplification circuits that amplify the outputs distributed by the power distribution circuit, and the 2 The fundamental wave of the input signal through each of the amplifier circuits is input from the two input terminals with the same amplitude and phase difference of 180 degrees, and is output to the two output terminals while maintaining the relationship of the same amplitude and phase difference of 180 degrees. A matching circuit that inputs a double wave of a signal from two input terminals with the same amplitude and the same phase and reflects them to the two input terminals, and a fundamental wave that is input with the same amplitude and a phase difference of 180 degrees through the matching circuit. A power combining circuit for combining and outputting , wherein the matching circuit includes a first line of one-eighth wavelength of a fundamental wave connected in series between one input terminal and one output terminal; One second track and the other The other first line and the other second line of the 1/8 wavelength fundamental wave connected in series between the input terminal and the other output terminal, the one first line, and the other one A third wave of a quarter wave with a fundamental wave connecting a connection point with a second line and a connection point between the other first line and the other second line; A fourth line of ¼ wavelength with a fundamental wave connecting a connection point between the second line and the one output terminal and a connection point between the other second line and the other output terminal; , One first open stub of a 1/8 wavelength fundamental wave connected to a connection point between the one first line and the one second line, the other first line, A first first open stub of a 1/8 wavelength fundamental wave connected to a connection point with the other second line; the one second line; A fundamental wave connected to a connection point with one output terminal and connected to a connection point between one second open stub of 1/8 wavelength and the other second line and the other output terminal. The other second open stub of 1/8 wavelength as the fundamental wave, the connection point between the one first line and the one input terminal, the other first line and the other input terminal. Two fifth lines having a quarter wave with a fundamental wave connected in series with a connection point between and a third open stub connected to a connection point between the two fifth lines. It is provided .

  According to the present invention, the second harmonic can be completely reflected without affecting the fundamental wave, and the phase condition for the second harmonic can be easily changed to improve the efficiency of the amplifier.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of a power amplifier according to Embodiment 1 of the present invention. The power amplifier according to the first embodiment shown in FIG. 1 distributes a fundamental wave of an input signal input from an input terminal 1 with the same amplitude and phase difference of 180 degrees and a power distribution circuit 4. Amplifying circuits 3-1 and 3-2 for amplifying the output signals respectively, and the fundamental wave of the input signal via the amplifying circuits 3-1 and 3-2 are input from two input terminals with the same amplitude and phase difference of 180 degrees. Then, the output is output to the two output terminals with the same amplitude and phase difference of 180 degrees, and the double wave of the input signal is input from the two input terminals with the same amplitude and the same phase and reflected to the two input terminals. A circuit 6 and a power combining circuit 5 that combines the fundamental wave input through the matching circuit 6 with the same amplitude and phase difference of 180 degrees and outputs the combined signal from the output terminal 2 are provided. 7-1 and 7-2 are connection points between the amplifier circuit 3 and the matching circuit 6, 8-1 and 8-2 are connection points between the matching circuit 6 and the power combining circuit 5, and 9-1 and 9-2. Is a connection point between the power distribution circuit 4 and the amplifier circuits 3-1 and 3-2.

  Next, the operation principle of the power amplifier having the above-described configuration will be described. The fundamental wave of the signal input to the input terminal 1 is distributed by the power distribution circuit 4 with the same amplitude and phase difference of 180 degrees, amplified by the amplifier circuits 3-1 and 3-2, and having the same amplitude and phase difference of 180 degrees. The relationship is output and input to the matching circuit 6. The fundamental wave input to the matching circuit 6 with the same amplitude and phase difference of 180 degrees is input to the power combining circuit 5 with the same amplitude and phase difference of 180 degrees and is combined and output from the output terminal 2.

  On the other hand, the double wave generated by the amplifier circuits 3-1 and 3-2 is input to the matching circuit 6 with the same amplitude and the same phase, and is completely reflected. Therefore, there is an effect that the efficiency of the amplifier is improved as compared with the case where the second harmonic wave is not completely reflected.

  As shown in FIG. 2, a matching circuit 6 similar to the matching circuit 6 may be inserted between the power distribution circuit 4 and the amplifier circuit 3, and in this case, the configuration is symmetric with respect to the amplifier circuit. Therefore, design verification becomes easy.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing the configuration of the power amplifier according to the second embodiment of the present invention. In particular, FIG. 3 is a block diagram showing the configuration in matching circuit 6 in detail. As shown in FIG. 3, the matching circuit 6 is a fundamental wave that is connected in series between the input terminals 7-1 and 7-2 and the output terminals 8-1 and 8-2, and has a 1 / 8th wavelength. Of the first line 10-1, 10-2 and the second line 11-1, 11-2, and the first line 10-1, 10-2 and the second line 11-1, 11-2. A third wave 12 of a quarter wavelength with a fundamental wave that connects the connection points, and connection points of the second lines 11-1 and 11-2 and the output terminals 8-1 and 8-2 are connected to each other. A fundamental wave connected to the connection point of the fourth line 13 having a quarter wavelength and the first lines 10-1 and 10-2 and the second lines 11-1 and 11-2. Are connected to the connection points of the first open stubs 14-1 and 14-2 of 1/8 wavelength and the second lines 11-1 and 11-2 and the output terminals 8-1 and 8-2. Basic And between the connection points of the second open stubs 15-1 and 15-2 of 1/8 wavelength and the first lines 10-1 and 10-2 and the input terminals 7-1 and 7-2. Two fifth lines 16-1 and 16-2 having a quarter wavelength with fundamental waves connected in series, and a first connected to a connection point of the two fifth lines 16-1 and 16-2. 3 open stubs 17.

  Next, the operation principle of the power amplifier according to the second embodiment will be described. The fundamental wave of the signal input to the input terminal 1 is distributed by the power distribution circuit 4 with the same amplitude and phase difference of 180 degrees, amplified by the amplifier circuit 3 and output with the relationship of the same amplitude and phase difference of 180 degrees, Input to the matching circuit 6.

  When a fundamental wave (anti-phase fundamental wave) having the same amplitude and phase difference of 180 degrees is input to the matching circuit 6, an electrical wall is formed on the symmetry plane, so that an input terminal 7-1 and an output terminal are provided as shown in FIG. The circuit between 8-1 is equivalent to a circuit in which the first line and the second line are connected in series. Accordingly, the signals are output with the same amplitude and phase difference of 180 degrees, and are combined by the power combining circuit 5 and output to the output terminal 2.

  On the other hand, the double wave generated by the amplifier circuit 3 is input to the matching circuit 6 with the same amplitude and the same phase. When a second harmonic wave (in-phase second harmonic wave) having the same amplitude and the same phase is input, a magnetic wall is formed on the symmetry plane. Therefore, as shown in FIG. 5, the fifth line and the third line are connected to the input terminal 7-1. Equivalent to a circuit in which open stubs are connected in series. Therefore, the second harmonic signal input to the matching circuit 6 is completely reflected by the open stub connected to the tip of the line having a half wavelength with respect to the second harmonic. Therefore, there is an effect that the efficiency of the amplifier is improved as compared with the case where the second harmonic wave is not completely reflected.

  Further, as shown in FIG. 6, the matching circuit 6 further increases the second lines 11-1 and 11-2, the fourth line 13, and the second open stubs 15-1 and 15-2 so as to increase the number of stages. In this case, there is an advantage that the characteristics can be widened.

  The power distribution circuit 4 that outputs the fundamental wave of the input signal with the same amplitude and phase difference of 180 degrees and the power combiner circuit 5 that synthesizes the fundamental wave input with the same amplitude and phase difference of 180 degrees are shown in FIGS. As shown in FIGS. 8, 9, and 10, a circuit in which a half-wave line with a fundamental wave is connected to one end of a distribution terminal of a Wilkinson distributor, or a quarter-wave wavelength with a fundamental wave is connected to one end of a branch line coupler. A circuit in which lines are connected, a circuit in which a quarter-wave line with a fundamental wave is connected to one end of a coupled line coupler, a rat race circuit, or the like may be used.

Embodiment 3 FIG.
FIG. 11 is a block diagram showing in detail the configuration in matching circuit 6 in the power amplifier according to the third embodiment of the present invention. In the configuration of the matching circuit 6 according to the third embodiment shown in FIG. 11, the same parts as those of the matching circuit 6 according to the second embodiment shown in FIG. As a new code, 18 is a stripe pattern provided at the tip of the third open stub 17, and the third open stub 17 has a predetermined phase angle with respect to the harmonics by the stripe pattern 18 provided at the tip. The length can be set to be

  By connecting the stripe pattern 18 and the open stub 17 with a ribbon or a wire, the length of the open stub can be changed. At this time, for the fundamental wave, as shown in FIG. 4, the length of the open stub does not depend, so the characteristic of the fundamental wave does not change. On the other hand, for the double wave, as shown in FIG. In addition, when the length of the open stub changes, the phase of reflection with respect to the second harmonic wave changes.

  FIG. 12 shows the calculation result of the input / output characteristics when the length of the third open stub 17 is changed. FIG. 12 shows the linear gain Gain in the fundamental wave when the electrical length of the third open stub 17 with respect to the fundamental wave is changed from 0 to 90 degrees as L, the output power P1 dB at the 1 decibel gain compression point, and the power added efficiency PAE. Is shown. In the second harmonic, the phase is twice that of the fundamental wave and doubles as it reciprocates. Therefore, if L is changed by 0 to 90 degrees, all changes of 360 degrees with respect to the second harmonic are covered. It will be. As shown in FIG. 12, since the change in L does not affect the fundamental wave, the linear gain hardly changes. On the other hand, since the power added efficiency changes depending on the phase of reflection with respect to the second harmonic wave, the efficiency is lowered under a certain phase condition.

  Therefore, even after the power amplifier is manufactured, connecting the stripe pattern 18 and the open stub 17 has an effect that the efficiency can be improved without changing characteristics such as gain and reflection.

Embodiment 4 FIG.
FIG. 13 is a diagram showing an equivalent circuit for the fundamental wave of matching circuit 6 in the power amplifier according to the fourth embodiment of the present invention. In FIG. 13, the same parts as those of the second embodiment shown in FIG.

  In FIG. 13, the characteristic impedance of the first line 10-1 and the second line 11-1 is the output impedance of the amplifier circuit 3-1 viewed from the input terminal 7-1, as viewed from the output terminal 8-1. It is set so as to be transformed into the input impedance of the power combining circuit 5.

  Even in this case, there are advantages similar to those of the first and second embodiments. Furthermore, since it is not necessary to make the output impedance of the amplifier circuit 3 (generically referred to as 3-1 and 3-2) and the input impedance of the power combining circuit 5 the same, there is an advantage that the degree of freedom in design is improved.

Embodiment 5. FIG.
FIG. 14 is a diagram showing an equivalent circuit for the fundamental wave of matching circuit 6 in the power amplifier according to the fifth embodiment of the present invention. In FIG. 14, the same parts as those of the second embodiment shown in FIG. Reference numeral 19 denotes an equivalent circuit for the fundamental wave in the power combining circuit 5.

  In FIG. 14, the characteristic impedances of the first line 10-1, the second line 11-1, and the power combining circuit 19 are changed to the output impedance of the amplifier circuit 3 as viewed from the input terminal 7-1. Set to transform.

  Even in this case, there are advantages similar to those of the first and second embodiments. Furthermore, since it is not necessary to make the output impedance of the amplifier circuit 3 and the impedance of the output terminal 2 the same, there is an advantage that the degree of design freedom is improved.

  In addition, since this is equivalent to an increase in the number of stages of lines for transforming impedance, there is also an advantage that the characteristics can be widened.

Embodiment 6 FIG.
FIG. 15 is a diagram showing an equivalent circuit for the fundamental wave of matching circuit 6 in the power amplifier according to the sixth embodiment of the present invention. In FIG. 15, the same parts as those of the second embodiment shown in FIG. As new reference numerals, reference numerals 20 and 21 denote a semiconductor element and a matching circuit section constituting the amplifier circuit 3, respectively.

  In FIG. 15, the characteristic impedance of the matching circuit unit 21 of the amplifier circuit 3, the first line 10-1 and the second line 11-1, and the output impedance of the semiconductor element 20 as viewed from the terminal 8. Set to transform to input impedance.

  Even in this case, there are advantages similar to those of the first and second embodiments. Furthermore, since it is not necessary to make the output impedance of the semiconductor element 20 and the input impedance of the power combining circuit 5 viewed from the terminal 8 the same, there is an advantage that the degree of freedom in design is improved.

  Further, since this is equivalent to an increase in the number of stages of lines for transforming impedance, there is an advantage that the characteristics can be further widened.

  Furthermore, there is also an advantage that the power amplifier can be miniaturized by omitting the matching circuit unit 21 and performing matching with the first line 10-1 and the second line 11-1.

Embodiment 7 FIG.
FIG. 16 is a diagram showing an equivalent circuit for the fundamental wave of matching circuit 6 in the power amplifier according to the seventh embodiment of the present invention. In FIG. 16, the same parts as those of the fifth embodiment shown in FIG. 14 and the sixth embodiment shown in FIG.

  In FIG. 16, the characteristic impedance of the equivalent circuit 19 with respect to the fundamental wave of the matching circuit unit 21 of the amplifier circuit 3, the first line 10, the second line 11, and the power combining circuit 5, and the output impedance of the semiconductor element 20 are output terminals. Set to transform to 2.

  Even in this case, there are advantages similar to those of the first and second embodiments. Further, since it is not necessary to make the output impedance of the semiconductor element 20 and the impedance of the output terminal 2 the same, there is an advantage that the degree of freedom in design is improved.

  Further, since this is equivalent to an increase in the number of stages of lines for transforming impedance, there is an advantage that the characteristics can be further widened.

  Furthermore, there is also an advantage that the power amplifier can be miniaturized by omitting the matching circuit 21 and performing matching by the first line 10, the second line 11, and the power combining circuit 19.

It is a block diagram which shows the structure of the power amplifier which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the power amplifier which concerns on the modification of Embodiment 1 of this invention. It is a block diagram which shows the structure of the power amplifier which concerns on Embodiment 2 of this invention, and is a block diagram which shows the structure in a matching circuit in detail especially. It is a figure explaining the equivalent circuit when the fundamental wave (antiphase fundamental wave) is input into the matching circuit 6 of FIG. 3 with the same amplitude and phase difference of 180 degrees. It is a figure explaining the equivalent circuit when the same amplitude and in-phase second harmonic (in-phase second harmonic) is input to the matching circuit 6 of FIG. It is a figure which shows the other structural example of the matching circuit 6 of FIG. FIG. 4 is a diagram illustrating a configuration example of the power distribution circuit 4 and the power combining circuit 5 in FIG. 3, and is a diagram illustrating a circuit in which a half-wave line with a fundamental wave is connected to one end of a distribution terminal of the Wilkinson distributor. 4 is a diagram illustrating a configuration example of the power distribution circuit 4 and the power combining circuit 5 in FIG. 3, and is a diagram illustrating a circuit in which a quarter-wave line with a fundamental wave is connected to one end of a branch line coupler. FIG. 4 is a diagram illustrating a configuration example of the power distribution circuit 4 and the power combining circuit 5 in FIG. 3, and is a diagram illustrating a circuit in which a quarter-wave line with a fundamental wave is connected to one end of a coupled line coupler. FIG. FIG. 4 is a diagram illustrating a configuration example of the power distribution circuit 4 and the power combining circuit 5 in FIG. 3 and is a diagram illustrating a rat race circuit. It is a block diagram which shows in detail the structure in the matching circuit 6 in the power amplifier which concerns on Embodiment 3 of this invention. It is a figure which shows the calculation result of the input-output characteristic when changing the length of a 3rd open stub. FIG. 10 is a diagram illustrating an equivalent circuit for a fundamental wave of a matching circuit 6 in a power amplifier according to a fourth embodiment of the present invention, and illustrating an example in which the output impedance of the amplifier circuit is transformed into the impedance of the input terminal of the power combining circuit. 7 shows an equivalent circuit for the fundamental wave of the matching circuit 6 in the power amplifier according to Embodiment 5 of the present invention, and shows an example in which the output impedance of the amplifier circuit is set to be transformed to the impedance of the output terminal of the power combining circuit. FIG. It is a figure which shows the equivalent circuit with respect to the fundamental wave of the matching circuit 6 in the power amplifier which concerns on Embodiment 6 of this invention. It is a figure which shows the equivalent circuit with respect to the fundamental wave of the matching circuit 6 in the power amplifier which concerns on Embodiment 7 of this invention.

Explanation of symbols

  1 input terminal, 3-1, 3-2 amplifier circuit, 4 power distribution circuit, 5 power combining circuit, 6 matching circuit, 10-1, 10-2 first line, 11-1, 11-2 second Line, 12 3rd line, 13 4th line, 14-1, 14-2 1st open stub, 15-1, 15-2 2nd open stub, 16-1, 16-2 5th Line, 17 Third open stub, 18 Stripe pattern, 19 Equivalent circuit for fundamental wave in power combining circuit 5, 20 Semiconductor element, 21 Matching circuit section.

Claims (6)

A power distribution circuit that distributes the fundamental wave of the input signal with the same amplitude and phase difference of 180 degrees;
Two amplifier circuits each amplifying the output distributed by the power distribution circuit;
The fundamental wave of the input signal through each of the two amplifier circuits is input from two input terminals with the same amplitude and phase difference of 180 degrees, and is output to the two output terminals while maintaining the relationship of the same amplitude and phase difference of 180 degrees. A matching circuit that inputs the second harmonic of the input signal with the same amplitude and the same phase from the two input terminals and reflects them to the two input terminals;
A power combining circuit that combines and outputs a fundamental wave input with the same amplitude and phase difference of 180 degrees via the matching circuit ;
The matching circuit includes:
One first line and one second line of a 1/8 wavelength fundamental wave connected in series between one input terminal and one output terminal;
The other first line and the other second line of the fundamental wave connected in series between the other input terminal and the other output terminal and having a 1/8 wavelength;
1/4 of a fundamental wave that connects a connection point between the one first line and the one second line and a connection point between the other first line and the other second line. A third line of wavelengths;
A fundamental wave that connects a connection point between the one second line and the one output terminal and a connection point between the other second line and the other output terminal, and has a fourth wavelength. And the track
One first open stub of 1/8 wavelength with a fundamental wave connected to a connection point between the one first line and the one second line;
A first open stub of the other 1/8 wavelength with a fundamental wave connected to a connection point between the other first line and the other second line;
A second open stub of one-eighth wavelength with a fundamental wave connected to a connection point between the one second line and the one output terminal;
The other second open stub of the fundamental wave connected to the connection point between the other second line and the other output terminal and having a wavelength of 1/8 wavelength;
A fundamental wave connected in series between the connection point between the one first line and the one input terminal and the connection point between the other first line and the other input terminal. Two fifth lines of four wavelengths;
A third open stub connected to the connection point of the two fifth lines;
A power amplifier comprising: The power amplifier according to claim 1 , wherein
A length of the third open stub is set so as to be a predetermined phase angle with respect to the harmonic. The power amplifier according to claim 1 , wherein
The matching circuit transforms an impedance of the amplifier circuit into an impedance of an input terminal of the power combining circuit. The power amplifier according to claim 1 , wherein
The matching circuit transforms an impedance of the amplifier circuit into an impedance of an output terminal of the power combining circuit. The power amplifier according to claim 1 , wherein
The amplifier circuit includes a semiconductor element and a matching circuit unit,
The matching circuit and the matching circuit unit in the amplifier circuit transform the impedance of the semiconductor element in the amplifier circuit into the impedance of the input terminal of the power combining circuit. The power amplifier according to claim 5 , wherein
The matching circuit, the power combining circuit, and the matching circuit unit in the amplifier circuit transform the impedance of the semiconductor element in the amplifier circuit into the impedance of the output terminal of the power combining circuit. .

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