JP2005039799A - Power amplifier, power distributor, and power synthesizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem wherein nonuniformity is generated in characteristics, by enlarging a circuit when a pair of serial resonant circuits are arranged, in order to provide high efficiency in a push-pull power amplifier. <P>SOLUTION: Distribution constant lines 105a, 105b have a line length, wherein the wavelength is one-half that of the fundamental wave, in order to make the phase of the fundamental wave component invert in a first signal which is amplified by a first amplifying element 102a. One end of the serial resonant circuit 106 is connected in parallel with a part between the distribution constant lines 105a, 105b where the phases of second-order harmonic components are inverted. The other end is connected to the output side of the second amplifying element 102b. The serial resonant circuit 106 cancels the second-order harmonic components by resonating with the frequency of the second-order harmonic components. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high frequency power amplifier, and more particularly to a push-pull type high frequency power amplifier, and a power distributor and power combiner used therefor.

  FIG. 6 is a diagram showing a configuration of a conventional push-pull type high frequency power amplifier. In FIG. 6, a conventional power amplifier 9 includes an input terminal 900, a balun / matching circuit 901, field effect transistors (hereinafter referred to as FETs) 902a and 902b of the same standard, and inductors connected to the drains of the FETs 902a and 902b. 903a, 903b, an output terminal 904, a distributed constant line 905 connected between the output terminal 904 and the drain of the FET 902a, and a series resonant circuit connected in parallel between the distributed constant line 905 and the drain of the FET 902a 906a and a series resonant circuit 906b connected in parallel between the output terminal 904 and the drain of the FET 902b.

  The balun / matching circuit 901 rotates the phase of the fundamental wave input to the input terminal 900, and outputs first and second signals having fundamental wave components of opposite phases. The first and second signals are amplified by FETs 902a and 902b, respectively. Here, the wavelength of the fundamental wave is λ. The length of the distributed constant line 905 is ½ wavelength (λ / 2) of the fundamental wave. The signal output from the FET 902a is rotated by 180 degrees in the phase of the fundamental wave component by the distributed constant line 905, and is synthesized with the signal output from the FET 902b. The synthesized signal is output from the output terminal 904.

  When the frequency of the fundamental wave is fo (= 1 / λ), the series resonance circuits 906a and 906b are set to resonate at a frequency 2fo that is twice that of fo. Therefore, the second harmonics having the same phase generated in the amplification elements 902a and 902b are short-circuited in the series resonance circuits 906a and 906b. Therefore, the conventional power amplifier 9 shown in FIG. 6 can suppress the occurrence of secondary distortion.

  FIG. 7 is a diagram showing a configuration of a conventional push-pull type power amplifier provided with a matching circuit in consideration of impedance with respect to harmonics (see Patent Document 1). In the conventional power amplifier shown in FIG. 7, the fundamental wave input to the input terminal 911 is output as two signals having opposite phases to each other by the phase inversion circuit 912, and the FETs 915, 915 are respectively passed through the matching circuits 913 and 914. It is input to 916.

  Distributed constant lines 917 and 918 are connected to the drains of the FETs 915 and 916. In the distributed constant lines 917 and 918, one end having a length L2 of a quarter wavelength of the fundamental wave that is short-circuited with respect to the even-order harmonics at a position having a length L1 that is an integral multiple of a quarter wavelength of the fundamental wave. The stubs 919 and 920 that are short-circuited are connected.

  Further, in the distributed constant lines 917 and 918, a capacitor connecting the distributed constant line 917 and the distributed constant line 918 at the position of the length L3 of 1/12 wavelength of the fundamental wave so as to be open to the third harmonic. 921 is connected. Further, a capacitor 922 is connected in the distributed constant lines 917 and 918 between the connection position of the capacitor 921 and the connection positions of the stubs 919 and 920 in order to achieve impedance matching with respect to the fundamental wave. The signals from the distributed constant lines 917 and 918 are combined in the same phase by the phase inverter 923 and output from the output terminal 924.

In the conventional power amplifier shown in FIG. 7, when the gate voltage of the FETs 915 and 916 is set to the pitch-off point and the input signal is sufficiently transferred, the drain voltage vd and the drain current id of the FET have shapes as shown in FIG. It becomes a waveform. That is, the drain voltage vd is a rectangular wave composed of a fundamental wave and odd-order harmonic components, and the drain current id is a half-wave rectified waveform composed of a fundamental wave and even-order harmonics. Therefore, since voltage and current do not exist at the same time, power consumption in the amplifying element is eliminated, and the efficiency is 100%.
Japanese Patent Laid-Open No. 05-029851

  In the conventional power amplifier shown in FIG. 6, it is necessary to provide series resonant circuits 906a and 906b for each pair of FETs in order to short-circuit the impedance with respect to the second harmonic.

  Further, in the conventional power amplifier shown in FIG. 7, it is necessary to provide stubs 919 and 920 for short-circuiting the impedance with respect to even-order harmonics for each pair of FETs.

  Therefore, any conventional power amplifier has a problem that the circuit becomes large.

  The pair of series resonance circuits and stubs must have the same characteristics. However, when amplifiers are integrated and modularized, the high frequency characteristics of a pair of series resonant circuits and stubs may differ slightly due to the influence of peripheral components. This causes variations in the gain characteristics.

  Therefore, an object of the present invention is to provide a high-efficiency power amplifier that is small in size and has little variation in characteristics. Furthermore, another object of the present invention is to provide a power distributor and a power combiner used in such a power amplifier.

  In order to solve the above problems, the present invention has the following features. The present invention is a power amplifier for amplifying a high-frequency signal, and is connected to a first amplifying element for amplifying a first signal, a first amplifying element and a push-pull type, A first amplifier having a line length for inverting the phase of the fundamental component in the first signal amplified by the first amplifier, and a second amplifier for amplifying the second signal having a phase opposite to the first signal. Are connected between the position on the first distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the output side of the second amplifying element, and the even-order harmonic to be short-circuited. A first resonance circuit that resonates in series at the frequency of the wave component; and an output terminal that synthesizes and outputs the signal from the first distributed constant line and the signal from the second amplifying element.

  According to the present invention, in the push-pull type power amplifier, one resonant circuit that is connected in series at a frequency at which the frequency of the desired even-order harmonic component is inverted and the phase of the even-order harmonic is inverted is provided. The even-order harmonics generated in the first and second amplifying elements are canceled out. As described above, since the occurrence of even-order harmonic distortion can be suppressed by one resonance circuit, a power amplifier in which the circuit is miniaturized can be provided. In addition, characteristic variation can be reduced as compared with a case where a resonance circuit for suppressing generation of even harmonic distortion is provided for each of two amplification elements used in a push-pull type power amplifier.

  Preferably, the line length of the first distributed constant line is ½ wavelength of the fundamental wave, and the position on the first distributed constant line for connecting the first resonant circuit is the first distributed constant. The first resonant circuit is in series resonance at the frequency of the second harmonic, being at a quarter wavelength of the fundamental wave from the end of the line.

  Thereby, since the line length of the first distributed constant line is ½ wavelength of the fundamental wave, the phase of the fundamental wave in the first signal is rotated by 180 degrees. Further, since the first resonance circuit is connected from the end of the first distributed constant line to the quarter wavelength of the fundamental wave, that is, the half wavelength of the second harmonic, the first resonance circuit At both ends of the resonance circuit, the phases of the second harmonics are inverted from each other. Furthermore, the first resonant circuit resonates in series at the frequency of the second harmonic, and thus acts as a short circuit for the second harmonic. Therefore, the second harmonic is canceled at the output ends of the first and second amplifying elements. In this way, a small power amplifier constituted by one resonance circuit is provided without providing a resonance circuit individually at the output end of each amplification element.

  Preferably, the first resonance circuit is a series resonance circuit in which inductors and capacitors are arranged symmetrically. Thereby, it is possible to prevent a shift in impedance when viewed from both ends of the first resonance circuit.

  Preferably, the first resonance circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. As a result, it is possible to prevent a shift in impedance when viewed from both ends of the first resonance circuit and to reduce the number of elements.

  Preferably, the power distributor further includes a power distributor for inputting the first and second signals to the first and second amplifying elements, respectively, and the power distributor divides the input signal into two, and one of the first and second signals is the first. Having a line length that inverts the phase of the fundamental wave component in the other signal from the distributing means, and the inverted signal as the second signal. Between the second distributed constant line input to the second amplifying element, the position on the second distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted, and the input side of the second amplifying element And a second resonance circuit that resonates in series at the frequency of the even-order harmonic component to be short-circuited.

  As a result, the first and second signals in which the even-order harmonics are short-circuited are input. In the power divider for inputting the first and second signals, one of the power dividers connected in series at the frequency of the desired even-order harmonic component and the phase of the even-order harmonic is inverted. The resonance circuit cancels even-order harmonics generated in the first and second amplifying elements. As described above, since a signal in which the generation of even-order harmonic distortion is suppressed by one resonance circuit can be input, a small power amplifier with a built-in power distributor can be provided. Since one resonance circuit is used, characteristic variation can be reduced.

  Preferably, the line length of the second distributed constant line is ½ wavelength of the fundamental wave, and the position on the second distributed constant line for connecting the second resonant circuit is the second distributed constant line. The second resonant circuit is in series resonance at the frequency of the second harmonic, being at a quarter wavelength of the fundamental wave from the end of the line.

  As a result, the line length of the second distributed constant line becomes ½ wavelength of the fundamental wave, so that the phase of the fundamental wave in the input signal rotates 180 degrees. Further, since the second resonance circuit is connected from the end of the second distributed constant line to a quarter wavelength of the fundamental wave, that is, a half wavelength of the second harmonic, the second resonance circuit At both ends of the resonance circuit, the phases of the second harmonics are inverted from each other. Furthermore, since the second resonant circuit resonates in series at the frequency of the second harmonic, it acts as a short circuit for the second harmonic. Therefore, the second harmonics are canceled out at the input ends of the first and second amplifying elements, and a small power amplifier that suppresses the generation of the second harmonic distortion is provided.

  Preferably, the second resonance circuit is a series resonance circuit in which inductors and capacitors are arranged symmetrically. As a result, it is possible to prevent a deviation in impedance when viewed from both ends of the second resonance circuit.

  Preferably, the second resonance circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. As a result, it is possible to prevent a shift in impedance when viewed from both ends of the second resonance circuit and to reduce the number of elements.

  The present invention also provides a power amplifier for amplifying a high-frequency signal, a power distributor that outputs a first signal and a second signal having a phase opposite to the first signal, and a first signal A first amplifying element for amplifying, a first amplifying element connected to the first amplifying element in a push-pull manner, a second amplifying element for amplifying the second signal, and amplified by the first amplifying element A power combiner that inverts the phase of the fundamental component in the first signal, combines the first signal with the inverted phase and the second signal amplified by the second amplifying element, and outputs the resultant signal; The power distributor divides the input signal into two, and distributes one of the signals as a first signal to the first amplifying element, and the phase of the fundamental component in the other signal from the distributing means A signal having a line length to be inverted and having the phase inverted is a second signal. Are connected between the distributed constant line input to the second amplifying element and the position on the distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the input side of the second amplifying element. And a resonance circuit that resonates in series at the frequency of the even-order harmonic component to be generated.

  As a result, a power amplifier incorporating a power distributor that suppresses the occurrence of even-order harmonic distortion is provided.

  Preferably, the line length of the distributed constant line is ½ wavelength of the fundamental wave, and the position on the distributed constant line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed constant line. By the way, the resonance circuit may be in series resonance at the frequency of the second harmonic. This provides a power distributor that suppresses the occurrence of second-order harmonic distortion.

  Preferably, the resonance circuit is a series resonance circuit in which inductors and capacitors are arranged symmetrically. As a result, it is possible to prevent a deviation in impedance when viewed from both ends of the resonance circuit.

  Preferably, the resonant circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. As a result, it is possible to prevent a shift in impedance when viewed from both ends of the resonance circuit and to reduce the number of elements.

  The present invention is also a power distributor for distributing an input signal into two, a distribution means for distributing the power of the input signal into two, and one of the signals distributed by the distribution means as a first signal. A first output terminal for output and a line length that inverts the phase of the fundamental wave component in the other signal that has been bi-distributed by the distributing means, and the signal with the phase inverted is defined as the second signal. A distributed constant line for output, a second output terminal for outputting a second signal from the distributed constant line, a position on the distributed constant line where the phase of the even harmonic component to be short-circuited is inverted, and the first And a resonance circuit that is in series resonance at a frequency of an even-order harmonic component that is desired to be short-circuited.

  This provides a power distributor that suppresses the occurrence of even-order harmonic distortion.

  Preferably, the line length of the distributed constant line is ½ wavelength of the fundamental wave, and the position on the distributed constant line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed constant line. By the way, the resonance circuit is characterized in that it resonates in series at the frequency of the second harmonic.

  This provides a power distributor that suppresses the occurrence of second-order harmonic distortion.

  Preferably, the resonance circuit is a series resonance circuit in which inductors and capacitors are arranged symmetrically. As a result, it is possible to prevent a deviation in impedance when viewed from both ends of the resonance circuit.

  Preferably, the resonant circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. As a result, it is possible to prevent a shift in impedance when viewed from both ends of the first resonance circuit and to reduce the number of elements.

  The present invention is also a power combiner for combining the input first signal and the second signal, the first input terminal for inputting the first signal, and the second A second input terminal for inputting a signal, a distributed constant line having a line length for inverting the phase of the fundamental wave component in the second signal from the second input terminal, and an even-order harmonic component to be short-circuited A resonance circuit connected in series between the position on the distributed constant line where the phase of the first phase is inverted and the first input terminal and resonating in series at the frequency of the even-order harmonic component to be short-circuited, and from the first input terminal 1 is combined with the signal from the distributed constant line.

  This provides a power combiner that suppresses the occurrence of even-order harmonic distortion.

  Preferably, the line length of the distributed constant line is ½ wavelength of the fundamental wave, and the position on the distributed constant line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed constant line. By the way, the resonance circuit is characterized in that it resonates in series at the frequency of the second harmonic.

  This provides a power combiner that suppresses the occurrence of second-order harmonic distortion.

  Preferably, the resonance circuit is a series resonance circuit in which inductors and capacitors are arranged symmetrically. Thereby, it is possible to prevent a shift in impedance when viewed from both ends of the first resonance circuit.

  Preferably, the resonant circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. As a result, it is possible to prevent a shift in impedance when viewed from both ends of the first resonance circuit and to reduce the number of elements.

  According to the present invention, a single resonant circuit that is connected in series to the position where the phase of the even-order harmonic is inverted and that is in series resonance at the frequency of the desired even-order harmonic component is the first and second amplifications. The even harmonics generated in the element are canceled out. Suppresses the generation of even-order harmonic distortion with a single resonance circuit, compared to the case where a resonance circuit for suppressing the generation of even-order harmonic distortion is provided for each of the two amplifying elements used in a push-pull type power amplifier. Therefore, it is possible to provide a power amplifier, a power divider, and a power combiner in which a circuit is miniaturized, and characteristic variations can be reduced.

Hereinafter, embodiments of the present invention will be described.
(First embodiment)
FIG. 1 is a diagram showing a configuration of a power amplifier 1 according to the first embodiment of the present invention. In FIG. 1, a power amplifier 1 includes an input terminal 100, a balun / matching circuit 101, a first amplifying element 102a, a second amplifying element 102b, and an inductor connected to the drain of the first amplifying element 102a. 103a, an inductor 103b connected to the drain of the second amplifying element 102b, an output terminal 104, and distributed constant lines 105a and 105b connected between the output terminal 104 and the drain of the first amplifying element 102a, And a series resonance circuit 106. The first amplifying element 102a and the second amplifying element 102b have the same standard.

  One end of the series resonant circuit 106 is connected in parallel between the distributed constant line 105a and the distributed constant line 105b. The other end is connected in parallel between the drain of the second amplifying element 102 b and the output terminal 104. The series resonance circuit 106 is set to resonate at the frequency of the second harmonic of the fundamental wave.

  Let λ be the wavelength of the fundamental wave component in the signal input to the input terminal 100. The lengths of the distributed constant lines 105a and 105b are 1/4 wavelength of the fundamental wave, that is, λ / 4. In FIG. 1, for ease of explanation, the distributed constant line 105a and the distributed constant line 105b are described as being separated from each other. However, actually, the two distributed constant lines are connected to each other, and A distributed constant line having a length of ½ wavelength of the wave is formed. The series resonant circuit 106 is connected to a position of a quarter wavelength of the fundamental wave from the drain side of the first amplifying element 102a in the distributed constant line.

  The balun / matching circuit 101 inverts the phase of the fundamental wave input to the input terminal 100 and outputs first and second signals having fundamental wave components that are out of phase with each other. The first and second amplifying elements 102 a and 102 b amplify two signals having opposite phases output from the balun / matching circuit 101. The signal output from the first amplifying element 102a by the distributed constant line 105a and the distributed constant line 105b is rotated in phase by 180 degrees, combined with the signal output from the second amplifying element 102b, and output. Output from terminal 104.

  Second harmonics generated in the first and second amplifying elements 102a and 102b are in phase with each other. When the frequency of the fundamental wave is fo, the wavelength λ2 of the second harmonic is 1 / (2fo). Therefore, the line length of the distributed constant line 105a is ½ wavelength with respect to the second harmonic. Therefore, the phase of the second harmonic is rotated by 180 degrees by the distributed constant line 105a. Since the series resonant circuit 106 is assumed to resonate at the frequency of the second harmonic, the second harmonic whose phase is rotated by 180 degrees by the distributed constant line 105a and the second harmonic output from the second amplifying element 102b are as follows. , They will cancel each other out. As a result, the power amplifier 1 can suppress secondary distortion.

(Second Embodiment)
FIG. 2 is a diagram showing a configuration of the power amplifier 2 according to the second embodiment of the present invention. In FIG. 2, a power amplifier 2 includes an input terminal 100, a balun / matching circuit 101, a first amplifying element 102a, a second amplifying element 102b, and an inductor connected to the drain of the first amplifying element 102a. 103a, the inductor 103b connected to the drain of the second amplifying element 102b, the output terminal 104, and the distributed constant lines 205a, 205b connected between the output terminal 104 and the drain of the first amplifying element 102a, 205c and series resonance circuits 206a and 206b. In FIG. 2, the same parts as those of the power amplifier 1 are denoted by the same reference numerals as those shown in FIG.

  One end of the series resonant circuit 206a is connected in parallel between the distributed constant line 205a and the distributed constant line 205b. The other end is connected in parallel between the drain of the second amplifying element 102 b and the output terminal 104. The series resonance circuit 206a is set to resonate at the frequency of the fourth harmonic of the fundamental wave.

  One end of the series resonant circuit 206b is connected in parallel between the distributed constant line 205b and the distributed constant line 205c. The other end is connected in parallel between the drain of the second amplifying element 102 b and the output terminal 104. The series resonance circuit 206b is set to resonate at the frequency of the second harmonic of the fundamental wave.

  The length of the distributed constant lines 205a and 205b is 1/8 wavelength of the fundamental wave. The length of the distributed constant line 205c is ¼ wavelength of the fundamental wave. In FIG. 2, for the sake of easy understanding, the distributed constant lines 205a, 205b, and 205c are described as being separated from each other. However, in reality, the three distributed constant lines are connected, and the fundamental wave 1 A distributed constant line having a length of / 2 wavelength is configured. The series resonant circuit 206a is connected to the position of 1/8 wavelength of the fundamental wave from the drain side of the first amplifying element 102a in the distributed constant line. Further, the series resonance circuit 206b is connected to a position of a quarter wavelength of the fundamental wave from the drain side of the first amplifying element 102a in the distributed constant line.

  The fundamental wave output from the first amplifying element 102a by the distributed constant line composed of the distributed constant lines 205a, 205b, and 205c is rotated by 180 degrees in phase, and the fundamental wave output from the second amplifying element 102b. The wave is combined and output from the output terminal 104.

  Further, the phase of the second harmonic is rotated by 180 degrees by the distributed constant line composed of the distributed constant lines 205a and 205b. Since the series resonance circuit 206b resonates at the second harmonic frequency, the second harmonic whose phase is rotated by 180 degrees and the second harmonic output from the second amplifying element 102b cancel each other. . As a result, the power amplifier 2 can cancel the second harmonic.

  Further, the phase of the fourth harmonic is rotated 180 degrees by the distributed constant line 205a. Since the series resonance circuit 206a resonates at the frequency of the fourth harmonic, the fourth harmonic whose phase is rotated by 180 degrees and the fourth harmonic output from the second amplifying element 102b cancel each other. . As a result, the power amplifier 2 can cancel the fourth harmonic.

  As shown in FIGS. 1 and 2, in the power amplifier according to the embodiment of the present invention, as a circuit for short-circuiting even-order harmonics to be canceled, a series resonant circuit that resonates at the frequency of the even-order harmonics is Connected to a predetermined position of the distributed constant line so as to bypass the output of one amplifying element and the output of the other amplifying element. As a result, even-order harmonics are canceled out by the series resonance circuit, so that occurrence of even-order harmonic distortion can be suppressed.

  It is to be noted that a power combining side configuration having a series resonance circuit as shown in FIGS. 1 and 2 is provided in the balun / matching circuit so as to output first and second signals having fundamental wave components of opposite phases. It may be.

  1 and / or 2 show the configuration for suppressing the second-order harmonic and / or the fourth-order harmonic, but the same configuration is adopted when other even-order harmonics are suppressed. be able to. Specifically, when it is desired to suppress the 2n (n is a natural number) order harmonic, the frequency of the even order harmonic to be canceled at the 1 / (4n) wavelength position of the fundamental wave from the output side of the amplification terminal in the distributed constant line. What is necessary is just to connect the series resonance circuit which resonates by.

  In addition to the position of the 1 / (4n) wavelength of the fundamental wave from the output side of the amplification terminal in the distributed constant line, the position where the series resonant circuit is connected is 1 / (4n of the fundamental wave from the output terminal side of the distributed constant line. ) It may be the position of the wavelength.

  If at least one series resonant circuit is connected, a desired effect can be obtained.

  In addition, at the position of λ / 4 where the phase of the second harmonic is inverted, the phase of the even harmonics other than the second harmonic is also inverted. Therefore, in the power amplifier 1 shown in FIG. 1, if a stub is provided so that the series resonance circuit 106 performs series resonance even at a wavelength of an even-order harmonic other than the second-order harmonic, an even-number other than the second-order harmonic is provided. The second harmonic will also be canceled out. In the case shown in FIG. 2 as well, if a stub is provided so that the series resonance circuit 206a or 206b resonates in series even with a wavelength of an even harmonic other than the second harmonic, an even number other than the second harmonic is provided. The second harmonic will also be canceled out. Thereby, it can be expected to obtain a desired effect.

(Example)
Examples of the present invention will be described below.
FIG. 3 is a circuit diagram showing an embodiment of the power amplifier of the present invention. 3, the power amplifier 3 includes an input terminal 301, a gate bias terminal 302, a drain bias terminal 303, an output terminal 304, an input coupling capacitor 311, a gate bias inductor 312, a drain bias inductor 313, and an output. The coupling capacitor 314, the first FET 341, the second FET 342, the composite terminal 351, the first distributed constant line 352, the inductor 361a, the capacitor 362, the inductor 361b, the distribution terminal 321, the second The distributed constant line 322, the inductor 331a, the capacitor 332, and the inductor 331b.

  The source of the first FET 341 and the source of the second FET 342 are each grounded. The first and second FETs 341 and 342 correspond to the first and second amplifying elements 102a and 102b in the first embodiment (see FIG. 1).

  The drain of the second FET 342 and the synthesis terminal 351 are connected. A first distributed constant line 352 is connected between the drain of the first FET 341 and the composite terminal 351. The first distributed constant line 352 is a line having a length of ½ wavelength of the fundamental wave. In the first distributed constant line 352, an inductor 361b, a capacitor 362, and an inductor 361a connected in series are connected in parallel at a position of a quarter wavelength of the fundamental wave from the gate side of the first FET 341. The One end of the inductor 361 a is connected in parallel between the composite terminal 351 and the drain of the second FET 342.

  The inductor 361a, the capacitor 362, and the inductor 361b constitute a first series resonance circuit 360. In the first series resonance circuit 360, the values of the inductor 361a, the capacitor 362, and the inductor 361b are set so that series resonance occurs at a frequency twice that of the fundamental wave. The first series resonance circuit 360 corresponds to the series resonance circuit 106 in the first embodiment (see FIG. 1). The first series resonance circuit 360, the first distributed constant line 352, and the combination terminal 351 constitute a power combiner 350. In the first series resonance circuit 360, the inductor and the capacitor are symmetrically connected so as to have an LCL relationship, so that the impedance when viewed from both ends of the first series resonance circuit 360 is equal, and the impedance Variation due to deviation can be prevented. The first series resonance circuit 360 may be configured to be a CLC series resonance circuit.

  A drain bias inductor 313 is connected between the composite terminal 351 and the drain bias terminal 303. An output coupling capacitor 314 is connected between the combining terminal 351 and the output terminal 304.

  An input coupling capacitor 311 is connected between the input terminal 301 and the distribution terminal 321. A gate bias inductor 312 is connected between the gate bias terminal 302 and the distribution terminal 321.

  A second distributed constant line 322 is connected between the distribution terminal 321 and the gate of the second FET 342. The distribution terminal 321 and the gate of the first FET 341 are connected. The second distributed constant line 322 is a line having a length of ½ wavelength of the fundamental wave. In the second distributed constant line 322, an inductor 331a, a capacitor 332, and an inductor 331b connected in series are connected in parallel at a position of a quarter wavelength of the fundamental wave from the gate side of the second FET 342. The One end of the inductor 331b is connected in parallel between the distribution terminal 321 and the gate of the first FET 341.

  The inductor 331a, the capacitor 332, and the inductor 331b constitute a second series resonance circuit 330. In the second series resonance circuit 330, the values of the inductor 331a, the capacitor 332, and the inductor 331b are set so that series resonance occurs at a frequency twice that of the fundamental wave. The second series resonant circuit 330, the second distributed constant line 322, and the distribution terminal 321 constitute a power distributor 320. The power distributor 320 corresponds to the balun / matching circuit 101 in the first embodiment (see FIG. 1). In the second series resonance circuit 330, the inductor and the capacitor are symmetrically connected so as to have an LCL relationship, so that the impedance when viewed from both ends of the second series resonance circuit 330 becomes equal, and the impedance Variation due to deviation can be prevented. Note that the second series resonance circuit 330 may be configured to be a CLC series resonance circuit.

Hereinafter, the operation of the power amplifier 3 shown in FIG. 3 will be described.
The fundamental wave input to the input terminal 301 is input to the distribution terminal 321 of the power distributor 320 via the input coupling capacitor 311 and is distributed as the first and second signals. The second input signal from the distribution terminal 321 is input to the gate of the second FET 342 via the second distributed constant line 322 having a length of ½ wavelength of the fundamental wave. The first signal from the distribution terminal 321 is directly input to the gate of the first FET 341.

  By the second distributed constant line 322, the phases of the fundamental wave component and the odd harmonic component in the second signal are rotated by 180 degrees. Therefore, the signal input to the gate of the second FET 342 and the signal input to the gate of the first FET 341 are in opposite phases in the fundamental wave component and the odd harmonic component, and in phase in the even harmonic component. Become. The gate bias is applied from the gate bias terminal 302 via the gate bias inductor 312.

  The second series resonant circuit 330 has a length of ¼ wavelength of the fundamental wave from the gate side of the second FET 342 in the second distributed constant line 322, that is, ½ of the second harmonic. It is connected at the wavelength length. Accordingly, since the phase of the second harmonic is rotated by 180 degrees at the connection point between the second series resonant circuit 330 and the second distributed constant line 322, both ends of the second series resonant circuit 330 are rotated. The second harmonics at are in opposite phases. The second series resonance circuit 330 is in series resonance at the frequency of the second harmonic and acts as a short circuit, so that the second harmonic is canceled out. Therefore, the second harmonic does not exist at the gate ends of the first FET 341 and the second FET 342.

  The second signal amplified by the second FET 342 is input to the synthesis terminal 351. On the other hand, the first signal amplified by the first FET 341 is input to the synthesis terminal 351 via the first distributed constant line 352 having a length of ½ wavelength of the fundamental wave. The first distributed constant line 352 rotates the phase of the fundamental wave component and the odd harmonic component in the first input signal by 180 degrees. Therefore, at the synthesis terminal 351, the second signal output from the second FET 342 and the first signal output from the first FET 341 are in phase in the fundamental wave component and the odd-order harmonic component. The drain bias is applied from the drain bias terminal 303 via the drain bias inductor 313.

  The first series resonance circuit 360 has a length of ¼ wavelength of the fundamental wave from the drain side of the first FET 341 in the first distributed constant line 352, that is, ½ of the second harmonic. It is connected at the wavelength length. Therefore, the phase of the second harmonic is rotated by 180 degrees at the connection point between the first series resonant circuit 360 and the first distributed constant line 352. In the signal output from the first amplifying element 341 and the signal output from the second amplifying element 342, the second harmonics are in phase with each other, and therefore the second harmonics at both ends of the first series resonant circuit 360. Are opposite to each other. The first series resonance circuit 360 is in series resonance at the frequency of the second harmonic and acts as a short circuit, so that the second harmonic is canceled out. Therefore, the second harmonic does not exist at the drain ends of the first FET 341 and the second FET 342.

  In this way, in the power amplifier having the circuit configuration shown in FIG. 3, since the second harmonic does not exist at the input / output terminals of the two FETs, distortion is suppressed and high efficiency is obtained. In addition, as a configuration for canceling the second harmonic, it is only necessary to provide one series resonant circuit on the power distributor side and one series resonant circuit on the power combiner side. Will be provided. Further, since one series resonant circuit is used in each of the power distributor and the power combiner as a short circuit for canceling the second harmonic, variation in the short circuit can be eliminated. As a result, a power amplifier in which variations in power characteristics are reduced is provided.

  The first series resonant circuit 360 and / or the second series resonant circuit 330 may be a distributed constant circuit. FIG. 4 shows a diagram in which the first series resonant circuit 360 and / or the second series resonant circuit 330 is the distributed constant line 400. In FIG. 4, the first series resonance circuit 360 and / or the second series resonance circuit 330 has an electrical length that is 1/4 of the wavelength of the fundamental wave (an electrical length that is 1/2 of the wavelength of the second harmonic). The distributed constant line 400 is provided. Since the second harmonics have opposite phases at both ends of the distributed constant line 400, the second harmonics are canceled at both ends of the distributed constant line 400.

  It is difficult for a series resonant circuit composed of passive elements such as an inductor and a capacitor to completely control the harmonic impedance at both ends of the series resonant circuit at a high frequency. However, by using a series resonant circuit composed of distributed constant lines, it is possible to easily control the impedance of the harmonics at both ends of the distributed constant line with high accuracy even at high frequencies. Therefore, by using a distributed constant line in the series resonance circuit, it is possible to cancel harmonic components even at a high frequency.

  In addition, as shown in FIG. 3, in the series resonance circuit, it is preferable to connect the passive elements symmetrically. However, the symmetrical connection increases the number of elements of the passive elements. However, if the distributed constant line is used, the impedance when viewed from both ends can be made equal, so that variations due to the deviation of the impedance can be prevented and the number of elements can be reduced.

  In the embodiment shown in FIG. 3, a series resonance circuit is provided as a second harmonic short circuit in the power distributor and the power combiner. However, a series resonance circuit may be provided only in one of them. .

  Note that the power distributor or the power combining circuit shown in FIG. 3 can be implemented as a single component. These components are not limited to those used in push-pull type power amplifiers.

  Note that the first and second series resonance circuits 360 and 330 may be configured to simultaneously resonate not only with the second harmonic, but also with other even harmonics to be short-circuited. As a result, the generation of even harmonics other than the second harmonic can be suppressed, and high efficiency can be achieved.

  The connection position of the first and second series resonance circuits 360 and 330 is a length of ½ wavelength of even-order harmonics from either side of the first and second distributed constant lines 352 and 322. It may be connected to the position. As a result, it is possible to suppress the generation of even harmonics to be short-circuited.

  For example, when it is desired to suppress the generation of the second harmonic and the fourth harmonic, consider a configuration in which each series resonance circuit is a distributed constant line. FIG. 5 is a diagram showing a configuration in which each series resonance circuit is used as a distributed constant line when generation of second harmonics and fourth harmonics is to be suppressed. A distributed constant line 401 having an electrical length of 1/8 of the wavelength of the fundamental wave (an electrical length of 1/2 of the wavelength of the fourth harmonic) plays a role of the series resonance circuit 206a shown in FIG. A distributed constant line 402 having an electrical length that is ¼ of the wavelength of the fundamental wave (an electrical length that is ½ of the wavelength of the second harmonic) plays a role of the series resonant circuit 206b shown in FIG. In this way, even-numbered harmonics are generated by connecting a distributed constant line that resonates with even-order harmonics to be short-circuited instead of a series resonant circuit using passive elements as shown in FIG. Can be suppressed, and high efficiency can be achieved. Here, the electrical length of the distributed constant line that resonates with the even-order harmonics to be short-circuited is half the wavelength of the even-order harmonics to be short-circuited. As shown in FIG. 5, the longer distributed constant line 402 may be bent so that the end of the shorter distributed constant line 401 and the end are aligned on a straight line. Also, the ends may be aligned on a straight line, for example, by crossing distributed constant lines. The same is true for the other even harmonics.

  Furthermore, if a circuit that controls odd harmonics is combined with the above configuration, higher efficiency can be expected.

  The power amplifier, power divider, and power combiner according to the present invention are useful in the field of communication equipment and the like because they are small in size, have small variations in characteristics, and are highly efficient.

The figure which shows the structure of the power amplifier 1 which concerns on the 1st Embodiment of this invention. The figure which shows the structure of the power amplifier 2 which concerns on the 2nd Embodiment of this invention. The circuit diagram which shows the Example of the power amplifier of this invention A diagram when the first series resonant circuit 360 and / or the second series resonant circuit 330 is the distributed constant line 400. A diagram showing a configuration in which each series resonant circuit is a distributed constant line when generation of second and fourth harmonics is to be suppressed. The figure which shows the structure of the conventional push pull type high frequency power amplifier The figure which shows the constitution of the conventional push pull type power amplifier which provides the matching circuit which considers the impedance to the harmonic The figure which shows the waveform of drain voltage vd of FET and drain current id in the power amplifier shown in FIG.

Explanation of symbols

1, 2, 3, Power amplifier 100, 301 Input terminal 101 Balun / matching circuit 102a First amplifying element 102b Second amplifying element 103a, 103b Inductor 104, 304 Output terminal 105a, 105b, 205a, 205b, 205c Distributed constant Lines 106, 206a, 206b Series resonant circuit 321 Distribution terminal 351 Synthesis terminal 341 First FET
342 second FET
352 First distributed constant line 322 Second distributed constant line 360 First series resonant circuit 330 Second series resonant circuit 320 Power distributor 350 Power combiner 302 Gate bias terminal 303 Drain bias terminal 311 Input coupling capacitor 312 Gate Bias inductor 313 Drain bias inductor 314 Output coupling capacitors 331a, 331b, 361a, 361b Inductors 332, 362 Capacitors 400, 401, 402 Distributed constant lines

Claims (20)

A power amplifier for amplifying a high-frequency signal,
A first amplifying element for amplifying the first signal;
A second amplifying element connected to the first amplifying element in a push-pull manner for amplifying a second signal having a phase opposite to that of the first signal;
A first distributed constant line having a line length that inverts the phase of the fundamental component in the first signal amplified by the first amplification element;
Connected between the position on the first distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the output side of the second amplifying element, and the even-order harmonic component to be short-circuited A first resonant circuit in series resonance at a frequency;
A power amplifier comprising: an output terminal that combines and outputs a signal from the first distributed constant line and a signal from the second amplifying element.   The line length of the first distributed constant line is ½ wavelength of the fundamental wave, and the position on the first distributed constant line for connecting the first resonant circuit is the first distribution. 2. The power amplifier according to claim 1, wherein the first resonant circuit is in series resonance at a frequency of a second-order harmonic at a quarter wavelength of the fundamental wave from an end of the constant line.   The power amplifier according to claim 2, wherein the first resonance circuit is a series resonance circuit in which an inductor and a capacitor are arranged symmetrically.   2. The power amplifier according to claim 1, wherein the first resonance circuit is a distributed constant line having an electrical length of ½ of the wavelength of the even-order harmonic component to be short-circuited. A power divider for inputting the first and second signals to the first and second amplifying elements, respectively;
The power distributor is
Distribution means for dividing an input signal into two and inputting one of the signals as the first signal to the first amplifying element;
A second distributed constant having a line length for inverting the phase of the fundamental component in the other signal from the distributing means and inputting the inverted signal to the second amplifying element as a second signal; Tracks,
Connected between the position on the second distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the input side of the second amplifying element, and the even-order harmonic component to be short-circuited The power amplifier according to claim 1, further comprising a second resonant circuit that resonates in series at a frequency.   The line length of the second distributed constant line is ½ wavelength of the fundamental wave, and the position on the second distributed constant line for connecting the second resonant circuit is the second distribution. 6. The power amplifier according to claim 5, wherein the second resonant circuit is in series resonance at a frequency of a second-order harmonic at a quarter wavelength of the fundamental wave from the end of the constant line.   The power amplifier according to claim 6, wherein the second resonance circuit is a series resonance circuit in which an inductor and a capacitor are arranged symmetrically.   6. The power amplifier according to claim 5, wherein the second resonance circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. A power amplifier for amplifying a high-frequency signal,
A power distributor that outputs a first signal and a second signal having a phase opposite to that of the first signal;
A first amplifying element for amplifying the first signal;
A second amplifying element connected to the first amplifying element in a push-pull manner for amplifying the second signal;
The phase of the fundamental component in the first signal amplified by the first amplifying element is inverted, and the first signal having the inverted phase and the second signal amplified by the second amplifying element are used. A power combiner that combines and outputs the two signals,
The power distributor is
Distribution means for dividing an input signal into two and inputting one of the signals as the first signal to the first amplifying element;
A distributed constant line that has a line length that inverts the phase of the fundamental wave component in the other signal from the distribution means, and that inputs the inverted signal to the second amplifying element as a second signal;
Connected between the position on the distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the input side of the second amplifying element, and in series at the frequency of the even-order harmonic component to be short-circuited A power amplifier including a resonant circuit that resonates.   The line length of the distributed parameter line is ½ wavelength of the fundamental wave, and the position on the distributed parameter line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed parameter line. The power amplifier according to claim 9, wherein the resonance circuit resonates in series at a frequency of a second harmonic.   The power amplifier according to claim 10, wherein the resonant circuit is a series resonant circuit in which an inductor and a capacitor are arranged symmetrically.   10. The power amplifier according to claim 9, wherein the resonance circuit is a distributed constant line having an electrical length of ½ of the wavelength of the even-order harmonic component to be short-circuited. A power distributor for dividing an input signal into two parts,
A distribution means for distributing the power of the input signal into two;
A first output terminal for outputting one of the two signals distributed by the distributing means as a first signal;
A distributed constant line having a line length that inverts the phase of the fundamental component in the other signal that has been bipartively distributed by the distributing means, and the signal having the inverted phase as a second signal;
A second output terminal for outputting the second signal from the distributed constant line;
Resonance connected in series between the position on the distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the first output terminal, and in series resonance at the frequency of the even-order harmonic component to be short-circuited And a power distributor.   The line length of the distributed parameter line is ½ wavelength of the fundamental wave, and the position on the distributed parameter line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed parameter line. The power divider according to claim 13, wherein the resonant circuit resonates in series at a second harmonic frequency.   The power divider according to claim 14, wherein the resonant circuit is a series resonant circuit in which inductors and capacitors are arranged symmetrically.   The power divider according to claim 13, wherein the resonant circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited. A power combiner for combining an input first signal and a second signal,
A first input terminal for inputting the first signal;
A second input terminal for inputting the second signal;
A distributed constant line having a line length for inverting the phase of the fundamental component in the second signal from the second input terminal;
Resonance that is connected between the position on the distributed constant line where the phase of the even-order harmonic component to be short-circuited is inverted and the first input terminal, and series-resonates at the frequency of the even-order harmonic component to be short-circuited Circuit,
A power combiner comprising: a combining unit that combines the first signal from the first input terminal and the signal from the distributed constant line.   The line length of the distributed parameter line is ½ wavelength of the fundamental wave, and the position on the distributed parameter line for connecting the resonant circuit is ¼ wavelength of the fundamental wave from the end of the distributed parameter line. The power combiner according to claim 17, wherein the resonant circuit resonates in series at a second harmonic frequency.   The power combiner according to claim 18, wherein the resonant circuit is a series resonant circuit in which inductors and capacitors are arranged symmetrically. 18. The power combiner according to claim 17, wherein the resonance circuit is a distributed constant line having an electrical length that is ½ of the wavelength of the even-order harmonic component to be short-circuited.

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