WO2020110298A1 - Émetteur - Google Patents

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Publication number
WO2020110298A1
WO2020110298A1 PCT/JP2018/044220 JP2018044220W WO2020110298A1 WO 2020110298 A1 WO2020110298 A1 WO 2020110298A1 JP 2018044220 W JP2018044220 W JP 2018044220W WO 2020110298 A1 WO2020110298 A1 WO 2020110298A1
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WIPO (PCT)
Prior art keywords
baseband signal
signal
envelope
power
amplifier
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PCT/JP2018/044220
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English (en)
Japanese (ja)
Inventor
一二三 能登
美博 濱松
田島　賢一
Original Assignee
三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2018/044220 priority Critical patent/WO2020110298A1/fr
Priority to JP2020557514A priority patent/JP6861908B2/ja
Publication of WO2020110298A1 publication Critical patent/WO2020110298A1/fr

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits

Definitions

  • the present invention relates to a transmitter that amplifies and transmits a modulated wave signal.
  • a conventional transmitter may include a Doherty amplifier in the final stage.
  • the Doherty amplifier described in Patent Document 1 includes a carrier amplifier and a peak amplifier, and by changing the control voltage supplied to the amplification element that constitutes each of the carrier amplifier and the peak amplifier, backoff from the output saturation power is performed.
  • the efficiency of the power taken (hereinafter referred to as back-off power) is increased.
  • Patent Document 1 has a problem in that although the efficiency at the back-off power is improved, the linearity is greatly reduced accordingly.
  • the present invention solves the above problems, and an object of the present invention is to obtain a transmitter that can improve both power efficiency and linearity.
  • a transmitter inputs a first baseband signal, which is one of equally distributed baseband signals, and outputs the first baseband signal according to the size of the envelope of the first baseband signal.
  • the first baseband signal which is the other of the equally-distributed baseband signals, is input according to the magnitude of the envelope of the second baseband signal.
  • a second correction unit that corrects the second baseband signal to an amplitude and a phase different from those of the first baseband signal, and the first baseband signal corrected by the first correction unit as an analog signal.
  • a first DA conversion section for converting into a digital signal, a second DA conversion section for converting the second baseband signal corrected by the second correction section into an analog signal, and an analog signal by the first DA conversion section
  • a first power amplifier for amplifying the first baseband signal converted into the analog signal
  • a second power amplifier for amplifying the second baseband signal converted into the analog signal by the second DA converter
  • a second transmission line through which the second baseband signal is transmitted, a first baseband signal transmitted through the first transmission line, and a second baseband signal transmitted through the second transmission line.
  • a third transmission line for transmitting and outputting the signal synthesized by the synthesizer.
  • the first baseband signal is corrected to have amplitudes and phases different from each other according to the magnitudes of the respective envelopes of the first baseband signal and the second baseband signal that are equally distributed.
  • FIG. 3 is a block diagram showing a configuration of a transmitter according to the first embodiment. It is a block diagram which shows the structure of the conventional Doherty amplifier.
  • FIG. 3A is a graph showing the relationship of the output power of the signal with respect to the size of the envelope of the signal corrected by the first correction unit.
  • FIG. 3B is a graph showing the relationship of the gain of the signal with respect to the size of the envelope of the signal corrected by the first correction unit.
  • FIG. 3C is a graph showing the relationship between the magnitude of the envelope of the signal corrected by the first correction unit and the phase of the signal.
  • FIG. 4A is a graph showing the relationship between the output power of the signal and the size of the envelope of the signal corrected by the second correction unit.
  • FIG. 4B is a graph showing the relationship between the magnitude of the envelope of the signal corrected by the second correction unit and the phase of the signal.
  • FIG. 4C is a graph showing the relationship between the amplitude of the signal corrected by the second correction unit and the amplitude of the signal.
  • FIG. 5A is a graph showing the relationship between the input power and the gain of a continuous wave (CW) signal.
  • FIG. 5B is a graph showing the relationship between the input power of the CW signal and the phase.
  • FIG. 5C is a graph showing the relationship between the output power of the CW signal and the power added efficiency (PAE).
  • FIG. 6A is a graph showing the relationship between the output power of a modulated wave signal and the adjacent channel leakage power ratio (ACPR).
  • FIG. 6B is a graph showing a spectrum of a normalized frequency and a signal power level of a modulated wave signal at a 6 dB backoff point.
  • FIG. 6C is a graph showing the relationship between the output power of the modulated wave signal and PAE.
  • FIG. 6 is a block diagram showing a configuration of a transmitter according to a second embodiment.
  • FIG. 8A is a graph showing the relationship between the magnitude of the envelope of a signal corrected by the second correction unit in the second embodiment and the output power of the signal.
  • FIG. 8B is a graph showing the relationship between the amplitude of the signal corrected by the second correction unit according to the second embodiment and the amplitude of the signal.
  • FIG. 8C is a graph showing the relationship between the size of the envelope of the signal corrected by the second correction unit in the second embodiment and the phase of the signal.
  • FIG. 9A is a graph showing the relationship between the input power and the gain of a CW signal.
  • FIG. 9B is a graph showing the relationship between the input power of the CW signal and the phase.
  • FIG. 9C is a graph showing the relationship between the output power of the CW signal and PAE.
  • FIG. 10A is a graph showing the relationship between the output power of a modulated wave signal and ACPR.
  • FIG. 10B is a graph showing a spectrum of the normalized frequency and the power level of the modulated wave signal.
  • FIG. 10C is a graph showing the relationship between the output power of a modulated wave signal and PAE.
  • FIG. 9 is a block diagram showing a configuration of a modified example of the transmitter according to the second embodiment.
  • FIG. 6 is a block diagram showing a configuration of a transmitter according to a third embodiment.
  • FIG. 11 is a block diagram showing a configuration of a modified example of the transmitter according to the third embodiment.
  • FIG. 1 is a block diagram showing the configuration of the transmitter according to the first embodiment.
  • the transmitter shown in FIG. 1 is a transmitter that amplifies and transmits a modulated wave signal, and includes a first correction unit 1, a second correction unit 2, a DAC 3, a DAC 4, a main amplifier 5, an auxiliary amplifier 6, and a line. 7, a line 8, a combiner 9 and a line 10.
  • the DAC 3 and the main amplifier 5 and the DAC 4 and the auxiliary amplifier 6 may be directly connected to each other, but may be connected via other components.
  • FIG. 1 omits the description of the components between them.
  • the transmitter shown in FIG. 1 is a Doherty amplifier in which the output signal of the main amplifier 5 and the output signal of the auxiliary amplifier 6 are combined by the combiner 9 and output.
  • the first correction unit 1 inputs the first baseband signal, which is one of the equally distributed baseband signals, and receives the first baseband signal according to the size of the envelope of the first baseband signal. Correct the amplitude and phase of the signal.
  • the second correction unit 2 inputs the second baseband signal, which is the other of the equally distributed baseband signals, and outputs the second baseband signal according to the size of the envelope of the second baseband signal. Correct the signal to a different amplitude and phase than the first baseband signal.
  • the DAC (digital-analog converter) 3 is a first DA conversion unit that converts the first baseband signal input from the first correction unit 1 into an analog signal.
  • the first baseband signal converted into an analog signal is output from the DAC 3 to the main amplifier 5.
  • the DAC 4 is a second DA converter that converts the second baseband signal input from the second corrector 2 into an analog signal.
  • the second baseband signal converted into the analog signal is output from the DAC 4 to the auxiliary amplifier 6.
  • the DAC3 and the DAC4 may be RFDAC (radio frequency digital-analog converter), and the frequency of the output signal from the DAC may be converted to a desired frequency.
  • the IF signal (intermediate frequency signal) output from the DAC may be frequency-converted by the mixer between the DAC and the power amplifier.
  • the IQ analog baseband signal output from the DAC may be frequency-converted by a quadrature modulator.
  • a driver amplifier that raises the output power to a desired level may be provided, or a band limiting filter that limits the frequency band of the output signal may be provided.
  • the main amplifier 5 is a first power amplifier that amplifies the first baseband signal converted into an analog signal by the DAC 3, and is, for example, a carrier amplifier of a Doherty amplifier.
  • the first baseband signal amplified by the main amplifier 5 is transmitted to the line 7.
  • the auxiliary amplifier 6 is a second power amplifier that amplifies the second baseband signal converted into an analog signal by the DAC 4, and is, for example, a peak amplifier of a Doherty amplifier.
  • the second baseband signal amplified by the auxiliary amplifier 6 is transmitted to the line 8.
  • the second baseband signal input to the auxiliary amplifier 6 is usually more electrical than the first baseband signal input to the main amplifier 5 on the ⁇ /4 line. It is delayed by a long time (90 degrees phase).
  • the main amplifier 5 is biased with class A or class AB, and the auxiliary amplifier 6 is set with a bias close to class C or class B.
  • the line 7 is a first transmission line through which the first baseband signal amplified by the main amplifier 5 is transmitted.
  • the line 8 is a second transmission line through which the second baseband signal amplified by the auxiliary amplifier 6 is transmitted.
  • the line 8 has a different electrical length than the line 7.
  • the combiner 9 is a combiner that combines the first baseband signal transmitted through the line 7 and the second baseband signal transmitted through the line 8.
  • the line 10 is a third transmission line through which the signal combined by the combiner 9 is transmitted and output from the output end.
  • the line 8 through which the output signal of the auxiliary amplifier 6 is transmitted has an electrical length such that the impedance seen from the combiner 9 to the auxiliary amplifier 6 is open. Is set.
  • the main amplifier 5 is transformed by the lines 7 and 10 into a load impedance of 100 ⁇ .
  • the line 7 has a characteristic impedance of 50 ⁇
  • the line 10 has a characteristic impedance of 50 ⁇ and is configured as a transmission line having an electrical length of ⁇ /4.
  • the combiner 9 combines the output signal of the main amplifier 5 and the output signal of the auxiliary amplifier 6. At this time, the main amplifier 5 is transformed into a load impedance of 50 ⁇ by the line 7 and the line 10.
  • FIG. 2 is a block diagram showing the configuration of a conventional Doherty amplifier.
  • the Doherty amplifier shown in FIG. 2 includes a splitter 100, a line 101, a main amplifier 102, an auxiliary amplifier 103, a line 104, a line 105, a combiner 106, and a line 107.
  • the splitter 100 equally distributes the modulated wave signal to the main amplifier 102 and the auxiliary amplifier 103.
  • the main amplifier 102 is a carrier amplifier of the Doherty amplifier, and is biased with class A or class AB.
  • the auxiliary amplifier 103 is a peak amplifier of the Doherty amplifier, and a bias close to class C or class B is set.
  • the characteristic impedance of the line 101 is 50 ⁇ and the electrical length is 60 degrees.
  • the characteristic impedance of the line 104 is 50 ⁇ and the electrical length is 180 degrees.
  • the characteristic impedance of the line 105 is 50 ⁇ and the electrical length is 120 degrees.
  • the characteristic impedance of the line 107 is 34.5 ⁇ and the electrical length is 90 degrees.
  • the second baseband signal input to the auxiliary amplifier 103 lags behind the first baseband signal input to the main amplifier 102 by the line 101 which is a ⁇ /6 line.
  • the auxiliary amplifier 103 is in the ON state, the output signal of the main amplifier 102 and the output signal of the auxiliary amplifier 103 are combined by the combiner 106.
  • the signal combined by the combiner 106 is transmitted through the line 107 and output from the output end.
  • the auxiliary amplifier 103 When the power of the input signal is low, only the main amplifier 102 operates and the auxiliary amplifier 103 is turned off. When the auxiliary amplifier 103 is in the OFF state, there is no combined loss in the combiner 106, and the output signal of the main amplifier 102 is output as it is. When the power of the input signal increases, ideally, the output power of the main amplifier 102 saturates, and at the same time, the auxiliary amplifier 103 operates.
  • the conventional auxiliary amplifier 103 may rise earlier or later than the output power of the main amplifier 102 is saturated. If the auxiliary amplifier 103 rises early near the saturated output power of the main amplifier 102, the power efficiency of the Doherty amplifier deteriorates. On the other hand, when the auxiliary amplifier 103 rises late near the saturated output power of the main amplifier 102, the linearity of the output of the Doherty amplifier is greatly deteriorated.
  • FIG. 3A is a graph showing the relationship between the magnitude of the envelope of the signal corrected by the first correction unit 1 and the output power of the signal.
  • FIG. 3B is a graph showing the relationship between the magnitude of the envelope of the signal corrected by the first correction unit 1 and the gain of the signal.
  • FIG. 3C is a graph showing the relationship between the size of the envelope of the signal corrected by the first correction unit 1 and the phase of the signal.
  • the characteristic indicated by the solid line is the behavior with respect to the size of the envelope of the first baseband signal corrected by the first correction unit 1 shown in FIG.
  • the characteristic indicated by the broken line is the behavior with respect to the size of the envelope of the signal input to the main amplifier 102 shown in FIG.
  • the arrow indicates the 2 dB gain compression point (hereinafter referred to as P2 dB) of the main amplifier 5.
  • P2dB is an output power level at which the 2dB gain is reduced, that is, a gain compression of 2dB occurs with respect to the ideal characteristic that the output power of the main amplifier 5 increases linearly.
  • FIG. 4A is a graph showing the relationship between the output power of the signal and the size of the envelope of the signal corrected by the second correction unit 2.
  • FIG. 4B is a graph showing the relationship between the magnitude of the envelope of the signal corrected by the second correction unit 2 and the phase of the signal.
  • the signal input to the auxiliary amplifier 6 is ideally delayed by the electric length of the ⁇ /4 line (corresponding to a phase of 90 degrees), but it is usually different by several tens of degrees.
  • FIG. 4C is a graph showing the relationship between the amplitude of the signal corrected by the second correction unit 2 and the amplitude of the signal.
  • the characteristic indicated by the solid line is the behavior with respect to the size of the envelope of the first baseband signal corrected by the second correction unit 2 shown in FIG.
  • the characteristic indicated by the broken line is the behavior of the signal input to the auxiliary amplifier 103 shown in FIG. 2 with respect to the size of the envelope.
  • the arrow indicates the 1 dB gain compression point of the main amplifier 5 (hereinafter referred to as P1 dB).
  • the second correction unit 2 controls the amplitude of the second baseband signal so that the auxiliary amplifier 6 is turned on when the output power of the main amplifier 5 is saturated.
  • the second correction unit 2 determines that the size of the envelope of the second baseband signal is from the 0.5 dB gain compression point (hereinafter referred to as P0.5 dB) which is near the output saturation power of the main amplifier 5.
  • P0.5 dB the 0.5 dB gain compression point
  • the amplitude characteristic and the phase characteristic of the second baseband signal are corrected so that the auxiliary amplifier 6 rises when it becomes P1 dB or more during the 3 dB gain compression point (hereinafter referred to as P3 dB).
  • the second correction unit 2 causes the auxiliary amplifier 6 to operate when the magnitude of the envelope of the second baseband signal becomes equal to or higher than the power between P0.5 dB and P3 dB of the Doherty amplifier including the main amplifier 5.
  • the amplitude characteristic and the phase characteristic of the second baseband signal may be corrected so as to rise.
  • the first correction unit 1 changes the envelope size of the first baseband signal. Output linearly with respect to.
  • the first correction unit 1 adjusts the amplitude and the phase to be constant as shown in FIGS. 3B and 3C. The first baseband signal is corrected and output.
  • the first correction unit 1 determines that the magnitude of the envelope of the first baseband signal is equal to or higher than the power between P0.5 dB and P3 dB, which is near the output saturation power of the main amplifier 5, Correction is performed so that the amplitude characteristic and the phase characteristic of the first baseband signal become constant.
  • the second correction unit 2 compares the amplitude of the second baseband signal with a constant rate as compared with the case where it is P1dB or more. It is corrected so that it is low and the phase becomes constant. For example, as shown in FIG. 4C, the second baseband signal is corrected so that its amplitude is 20 dB lower and its phase is constant as shown in FIG. 4B.
  • the second correction unit 2 uses the second baseband signal until the envelope of the second baseband signal reaches a certain magnitude, for example, the power between P0.5 dB and P3 dB of the main amplifier 5.
  • the amplitude of the signal is lowered at a constant rate, and the phase is corrected so as to be constant.
  • the second correction unit 2 may correct the amplitude of the second baseband signal to zero.
  • the second correction unit 2 ensures that the amplitude and phase characteristics of the signal in the state where the auxiliary amplifier 6 is not raised. Will be corrected.
  • the second correction unit 2 converts the second baseband signal into the envelope of the second baseband signal as shown in FIG. 4A. Output linearly with respect to size.
  • the second correction unit 2 compares the second baseband signal with the second baseband signal with an envelope size of less than P1 dB of the main amplifier 5. The amplitude is corrected to increase at a constant rate (20 dB in FIG. 4C).
  • the second correction unit 2 makes the amplitude of the second baseband signal constant. Correct so that the ratio becomes higher. As described above, the second correction unit 2 prevents the auxiliary amplifier 6 from rising in a state in which the auxiliary amplifier 6 is delayed from the vicinity of the output saturation power of the main amplifier 5, and thus the amplitude characteristic and the phase of the signal in the state in which the auxiliary amplifier 6 is started are increased. It is corrected to the characteristics.
  • the second correction unit 2 changes the phase of the second baseband signal as shown in FIG. 4B. Correct so that it changes with a slope of 2.8 deg/dB. In this way, the second correction unit 2 outputs the second baseband signal when the magnitude of the envelope of the second baseband signal is equal to or larger than the power between P0.5 dB and P3 dB of the main amplifier 5. The phase is corrected so as to change with a constant slope with respect to the size of the envelope of the second baseband signal. At this time, the second correction unit 2 may correct the phase of the second baseband signal to have a characteristic opposite to that of the auxiliary amplifier 6.
  • FIG. 5A is a graph showing the relationship between the input power and the gain of a continuous wave (CW) signal.
  • FIG. 5B is a graph showing the relationship between the input power of the CW signal and the phase.
  • FIG. 5C is a graph showing the relationship between the output power of the CW signal and the power added efficiency (PAE).
  • the solid line is the characteristic when the CW signal is input to the transmitter shown in FIG. 1, and the broken line is the CW signal input to the conventional Doherty amplifier shown in FIG. It is a characteristic of time.
  • 5C is the power obtained by taking a backoff of 6 dB from the saturation power of the main amplifier, and this power is described as a 6 dB backoff point. As shown in FIG. 5C, it has a first peak of power efficiency at the 6 dB back-off point and a second peak on the high power side.
  • FIG. 6A is a graph showing the relationship between the output power of the modulated wave signal and the adjacent channel leakage power ratio (ACPR).
  • FIG. 6B is a graph showing a spectrum of the normalized frequency of the modulated wave signal and the signal power level at the 6 dB backoff point.
  • the spectrum 200 is the spectrum of the transmitter shown in FIG. 1
  • the spectrum 201 is the spectrum of the conventional Doherty amplifier shown in FIG.
  • FIG. 6C is a graph showing the relationship between the output power of the modulated wave signal and PAE.
  • the solid line represents the characteristic when the modulated wave signal is input to the transmitter shown in FIG.
  • the broken line inputs the modulated wave signal into the conventional Doherty amplifier shown in FIG. It is a characteristic when it is done.
  • the arrow in FIG. 6C is the 6 dB backoff point of the main amplifier.
  • the gain and the phase do not significantly change between the conventional Doherty amplifier and the transmitter of FIG. 1, but as shown in FIG. At high power, the power efficiency of the transmitter of Figure 1 is greatly increased.
  • the error vector magnitude (EVM) characteristic is almost unchanged between the conventional Doherty amplifier and the transmitter of FIG.
  • EVM error vector magnitude
  • FIG. 6A the ACPR characteristics are almost the same between the conventional Doherty amplifier and the transmitter of FIG.
  • FIG. 6C the efficiency of the transmitter of FIG. 1 is higher than that of the conventional Doherty amplifier due to the power lower than the 6 dB backoff point.
  • the spectrum of the normalized frequency and the output level at the 6 dB back-off point are almost the same in the spectrum 200 of the transmitter in FIG. 1 and the spectrum 201 of the conventional Doherty amplifier.
  • the efficiency is improved by correcting the baseband signal by the first correction unit 1 and the second correction unit 2.
  • the second correction unit 2 corrects the amplitude and phase of the second baseband signal so that the auxiliary amplifier 6 is turned on when the output power of the main amplifier 5 is saturated, and thus the output Linearity is improved.
  • the amplitude and the phase are corrected to be different from each other according to the size of the envelope of each of the first baseband signal and the second baseband signal that are evenly distributed. Then, by inputting the first baseband signal to the main amplifier 5 and inputting the second baseband signal to the auxiliary amplifier 6, this occurs incidentally when the power efficiency of the backoff power is improved. Deterioration of linearity is suppressed. This makes it possible to improve power efficiency and linearity at the same time.
  • FIG. 7 is a block diagram showing the configuration of the transmitter according to the second embodiment. 7, the same components as those of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.
  • the transmitter shown in FIG. 7 is a transmitter that amplifies and transmits a modulated wave signal, and includes a first correction unit 1, a second correction unit 2, a DAC 3, a DAC 4, a main amplifier 5, an auxiliary amplifier 6, and a line 7. , Line 8, combiner 9, line 10, feedback path 13, ADC (analog-digital converter) 14, comparing unit 15, coefficient calculating unit 16, delay adjusting unit 17, DSP (digital signal processor) 18, distortion compensating unit 19, and splitter. Equipped with 20.
  • the feedback path 13 is a path for feeding back the signal transmitted on the line 10 to the ADC 14.
  • the ADC 14 is an AD converter that converts a signal fed back via the feedback path 13 into a digital signal.
  • the comparison unit 15 compares the signal fed back via the feedback path 13 with the baseband signal before being equally distributed by the splitter 20.
  • the coefficient calculation unit 16 calculates a distortion compensation coefficient according to the result of the comparison by the comparison unit 15.
  • the delay adjusting unit 17 adjusts the delay ⁇ with respect to the baseband signal output from the DSP 18, and outputs it to the distortion compensating unit 19.
  • the DSP 18 outputs the baseband signal before being equally distributed by the splitter 20.
  • the distortion compensating unit 19 uses the compensation coefficient calculated by the coefficient calculating unit 16 to perform distortion compensation on the baseband signal before being equally distributed by the splitter 20.
  • the splitter 20 is a distributor that evenly distributes the baseband signal whose distortion is compensated by the distortion compensator 19 to the first corrector 1 and the second corrector 2.
  • the delay adjustment unit 17 inputs the baseband signal that is output from the DSP 18 and is not equally distributed by the splitter 20, and the time of the input baseband signal is fed back via the feedback path 13. Adjust the delay ⁇ so that The comparison unit 15 compares the baseband signal delay-adjusted by the delay adjustment unit 17 with the baseband signal fed back via the feedback path 13 to generate a difference signal indicating an error between the two, and the generated difference signal. Is output to the coefficient calculation unit 16.
  • the coefficient calculation unit 16 determines that the error between the baseband signal delay-adjusted by the delay adjustment unit 17 and the baseband signal fed back via the feedback path 13 is the minimum based on the difference signal input from the comparison unit 15. Then, the distortion compensation coefficient is calculated.
  • the distortion compensation unit 19 uses the distortion compensation coefficient calculated by the coefficient calculation unit 16 to perform distortion compensation on the baseband signal.
  • the DAC 3 and the main amplifier 5 and the DAC 4 and the auxiliary amplifier 6 may be directly connected to each other, but may be connected via other components.
  • FIG. 1 omits the description of the components between them.
  • the transmitter shown in FIG. 7 is a Doherty amplifier in which the output signal of the main amplifier 5 and the output signal of the auxiliary amplifier 6 are combined by the combiner 9 and output.
  • the feedback path 13 and the ADC 14 may be directly connected. Further, the ADC 14 may convert a high frequency signal from an analog signal to a digital signal, a mixer may be arranged to frequency-convert the high frequency signal into an IF signal, or a band limiting filter may be arranged to convert the high frequency signal. You may limit the band.
  • the transmitter shown in FIG. 7 is a Doherty amplifier in which the output signal of the main amplifier 5 and the output signal of the auxiliary amplifier 6 are combined by the combiner 9 and output.
  • the linearity of the output characteristic sharply deteriorates from near the gain compression point of the main amplifier 5. Even if the auxiliary amplifier 6 is in the ON state, since it is in the class C operation, even if the output signal of the auxiliary amplifier 6 is combined with the output signal of the main amplifier 5, it hardly contributes to the linearity of the output of the entire amplifier. That is, in the Doherty amplifier, the deterioration of the linearity of the output due to the gain compression of the main amplifier 5 is dominant, and when this Doherty amplifier is used for communication, it is necessary to perform distortion compensation.
  • the first correction unit 1 performs the first correction when the magnitude of the envelope of the input first baseband signal is less than P2 dB of the main amplifier 5, as shown in FIG. 3A.
  • the baseband signal of is output linearly with respect to the size of the envelope.
  • the first correction unit 1 keeps the amplitude and phase constant as shown in FIGS. 3B and 3C.
  • the first baseband signal is corrected so as to be output.
  • the first correction unit 1 outputs the first baseband signal. Correction is performed so that the amplitude characteristic and the phase characteristic are constant.
  • FIG. 8A is a graph showing the relationship between the size of the envelope of the signal corrected by the second correction unit 2 and the output power of the signal.
  • FIG. 8B is a graph showing the relationship between the amplitude of the signal corrected by the second correction unit 2 and the amplitude of the signal.
  • FIG. 8C is a graph showing the relationship between the envelope size of the signal corrected by the second correction unit 2 and the phase of the signal.
  • the solid line is the behavior with respect to the size of the envelope of the first baseband signal corrected by the second correction unit 2 shown in FIG. 7.
  • the broken line represents the behavior of the modulated wave signal input to the auxiliary amplifier 103 shown in FIG. 2 with respect to the size of the envelope.
  • the arrow in FIGS. 8A and 8B is P0.5 dB of the main amplifier 5.
  • the arrow a indicates P0.5 dB of the main amplifier 5
  • the arrow b indicates P1 dB of the main amplifier 5.
  • the second correction unit 2 causes the amplitude of the second baseband signal to be low at a constant rate and the phase to be low. Correct so that it becomes constant. For example, as shown in FIG. 8B, the amplitude of the second baseband signal is corrected to be 20 dB lower than that of the signal output from the auxiliary amplifier 103 so that the phase becomes constant as shown in FIG. 8C. Will be corrected.
  • the second correction unit 2 changes the signal output from the auxiliary amplifier 103 as shown in FIG. 8B. The amplitude of the second baseband signal is corrected so that the gain is expanded by 4 dB.
  • the second correction unit 2 determines that the envelope size of the second baseband signal is less than P0.5 dB (point a) of the main amplifier 5 and the main amplifier 5.
  • the phase of the second baseband signal is corrected to be constant.
  • the second correction unit 2 uses the second baseband signal until the envelope of the second baseband signal reaches a certain level, for example, the power between P0.5 dB and P3 dB of the main amplifier 5 or more.
  • the amplitude of the band signal is lowered at a constant rate and the phase is corrected so that it becomes constant.
  • the second correction unit 2 may correct the amplitude of the second baseband signal to zero.
  • the second correction unit 2 changes the phase of the second baseband signal with a slope of 2.8 deg/dB. To correct. In this way, the second correction unit 2 receives the second baseband signal when the magnitude of the envelope of the second baseband signal is equal to or larger than the power between P0.5 dB and P3 dB of the main amplifier 5. Is corrected so that it changes with a constant slope with respect to the size of the envelope of the second baseband signal. At this time, the second correction unit 2 may correct the phase of the second baseband signal to have a characteristic opposite to that of the auxiliary amplifier 6.
  • FIG. 9A is a graph showing the relationship between the input power and the gain of a continuous wave (CW) signal.
  • FIG. 9B is a graph showing the relationship between the input power of the CW signal and the phase.
  • FIG. 9C is a graph showing the relationship between the output power of the CW signal and the power added efficiency (PAE).
  • PAE power added efficiency
  • 9A, 9B and 9C the solid line shows the characteristics when the CW signal is input to the transmitter shown in FIG. 1, and the broken line shows the characteristics when the CW signal is input to the conventional Doherty amplifier shown in FIG. It is a characteristic.
  • the arrow in FIG. 9C indicates the power obtained by backoff of 6 dB from the saturation power of the main amplifier.
  • this power is referred to as a 6 dB back-off point.
  • FIG. 9C it has a first peak of power efficiency at the 6 dB back-off point and a second peak on the high power side.
  • FIG. 10A is a graph showing the relationship between the output power of a modulated wave signal and ACPR.
  • FIG. 10B is a graph showing the spectrum of the normalized frequency of the modulated wave signal and the signal power level at the 6 dB backoff point.
  • spectrum 200 is the spectrum of the transmitter shown in FIG. 1
  • spectrum 201 is the spectrum of the conventional Doherty amplifier shown in FIG.
  • FIG. 10C is a graph showing the relationship between the output power of a modulated wave signal and PAE.
  • the solid line represents the characteristic when the modulated wave signal is input to the transmitter illustrated in FIG. 7, and the broken line represents the modulated wave signal in the conventional Doherty amplifier illustrated in FIG. It is a characteristic when input.
  • the arrow in FIG. 10C is the 6 dB backoff point of the main amplifier.
  • the transmitter of FIG. 7 has a gain increased up to a high output range as compared with the conventional Doherty amplifier, and is shown in FIG. 9B.
  • the phase rotation amount is small.
  • FIG. 9C at a power lower than the 6 dB backoff point, the PAE peak is higher in the conventional Doherty amplifier than in the transmitter in FIG. 7, but the transmission in FIG. 7 is higher than that in the conventional Doherty amplifier. It can be seen that the aircraft has less dents from the peak.
  • the ACPR characteristics of the transmitter of FIG. 7 are improved and the ACPR is higher by about 5 points than the conventional Doherty amplifier, as shown in FIG. 10A.
  • the spectrum distortion at the 6 dB backoff point is lower than that of the spectrum 201 of the conventional Doherty amplifier.
  • the linearity of the output power is improved while the power efficiency is maintained by the correction of the baseband signal by the first correction unit 1 and the second correction unit 2.
  • FIG. 11 is a graph showing a spectrum of a normalized frequency and an electric power level of an output signal subjected to digital predistortion.
  • the spectrum 200 of the normalized frequency and power level of the output signal shows the result of digital predistortion performed on the transmitter of FIG. 7.
  • a spectrum 201 shows the result of applying digital predistortion to the Doherty amplifier shown in FIG.
  • MP memory polynomial
  • Both the spectrum 200 and the spectrum 201 are spectra at the 6 dB back-off point.
  • the transmitter of FIG. 7 can obtain more distortion compensation amount than the Doherty amplifier of FIG. 2 in spite of higher power efficiency.
  • the distortion compensation amount can be obtained without using a complicated compensation method for distortion compensation, so that complicated calculation processing is not required, and therefore, it is not necessary to perform distortion compensation.
  • the storage area required for arithmetic processing of digital signals can be reduced.
  • the distortion due to the memory effect increases as the modulation wave band of the modulation wave signal becomes wider.
  • the memory effect occurs due to various factors, but particularly due to frequency characteristics.
  • the impedance is different when the auxiliary amplifier 6 is in the off state and when it is in the on state, and while the auxiliary amplifier 6 is in the on state, the impedance of the auxiliary amplifier 6 changes as the input power increases.
  • the operation classes of the main amplifier 5 and the auxiliary amplifier 6 are different, so that a memory effect is more likely to occur as compared with an amplifier of a type other than the Doherty amplifier.
  • FIG. 12 is a block diagram showing a configuration of a modified example of the transmitter according to the second embodiment. 12, the same components as those of FIG. 7 are designated by the same reference numerals and the description thereof will be omitted.
  • the transmitter shown in FIG. 12 has a CFIR 21 between the first correction unit 1 and the DAC 3 in the configuration shown in FIG. 7 in order to compensate the distortion due to the memory effect described above, and the second correction unit 2 CFIR22 is provided between the CPU4 and the DAC4.
  • the CFIR 21 is a first FIR filter that corrects the frequency characteristic of the output signal of the main amplifier 5.
  • the CFIR 22 is a second FIR filter that corrects the frequency characteristic of the output signal of the auxiliary amplifier 6.
  • CFIR is an abbreviation for complex FIR.
  • the CFIR 21 corrects the frequency characteristic of the output signal of the main amplifier 5, and the CFIR 22 corrects the frequency characteristic of the output signal of the auxiliary amplifier 6, so that the memory effect caused by the frequency characteristic of each of the main amplifier 5 and the auxiliary amplifier 6 is corrected. It is possible to reduce the memory effect when the combined wave signals are combined by the combiner 9. That is, by including the CFIR 21 and the CFIR 22, distortion in the output signal of the transmitter according to the second embodiment is compensated, and the distortion compensation amount due to digital predistortion is further improved as compared with the transmitter without CFIR. ..
  • the transmitter according to the second embodiment since the transmitter according to the second embodiment has the components shown in FIG. 7, it is possible to obtain the distortion compensation amount without using a complicated compensation method for distortion compensation, so that a complicated calculation is performed. Since no processing is required, the storage area required for digital signal arithmetic processing such as distortion compensation can be reduced.
  • the CFIR 21 is provided between the first correction unit 1 and the DAC 3
  • the CFIR 22 is provided between the second correction unit 2 and the DAC 4.
  • FIG. 13 is a block diagram showing the configuration of the transmitter according to the third embodiment. 13, the same components as those of FIG. 12 are designated by the same reference numerals and the description thereof will be omitted.
  • the transmitter shown in FIG. 13 is a transmitter that amplifies and transmits a modulated wave signal, and includes a first correction unit 1, a second correction unit 2, a DAC 3, a DAC 4, a main amplifier 5, an auxiliary amplifier 6, and a line 7.
  • Line 8 combiner 9, line 10, feedback path 13, ADC 14, comparison unit 15, coefficient calculation unit 16, delay adjustment unit 17, DSP 18, distortion compensation unit 19, splitter 20, CFIR 21, CFIR 22, envelope extraction unit 23, envelope
  • the extraction unit 24, the power supply control unit 25, the DAC 26, the DAC 27, the power supply 28, the power supply 29, the power supply modulation unit 30, and the switch 31 are provided.
  • the envelope extraction unit 23 is a first envelope extraction unit that extracts the envelope signal of the first baseband signal corrected by the first correction unit 1.
  • the envelope extraction unit 24 is a second envelope extraction unit that extracts the envelope signal of the second baseband signal corrected by the second correction unit 2.
  • the DAC 26 converts the envelope signal extracted by the envelope extraction unit 23 into an analog first envelope signal.
  • the DAC 27 converts the control signal from the power supply control unit 25 into an analog control signal.
  • the power supply 28 is a power supply that outputs a bias voltage applied to the main amplifier 5
  • the power supply 29 is a power supply that outputs a bias voltage applied to the auxiliary amplifier 6.
  • the switch 31 is a switch that switches on (applying) and off (interrupting) the bias voltage applied to the auxiliary amplifier 6 from the power supply 29.
  • the power supply control unit 25 switches according to the magnitude of the second envelope signal.
  • the auxiliary amplifier 6 When the auxiliary amplifier 6 is composed of a field effect transistor (hereinafter, referred to as FET), when the auxiliary amplifier 6 is in the off state, normally, the drain voltage of the FET is still applied, and the operation voltage is at the gate voltage. Is determined.
  • the auxiliary amplifier 6 as power loss Loss impedance Z off when in the OFF state is reduced is increased, which decreases power efficiency.
  • auxiliary amplifier 6 if it is turned off, the gate voltage and the drain voltage of the FET constituting the auxiliary amplifier 6 and 0V, the auxiliary amplifier 6 increases the impedance Z off when in the OFF state .
  • the auxiliary amplifier 6 in which the gate voltage and the drain voltage are set to 0V is different in the change tendency of the amplitude and phase of the output signal with respect to the size of the envelope of the second baseband signal, as compared with the case of the class C operation. Therefore, the second correction unit 2 corrects the amplitude and phase of the second baseband signal.
  • the envelope extraction unit 24 extracts the second envelope signal of the second baseband signal input to the auxiliary amplifier 6 and outputs the second envelope signal to the power supply control unit 25.
  • the power supply control unit 25 generates an ON/OFF control signal for the auxiliary amplifier 6 according to the magnitude of the second envelope signal, and outputs the generated ON/OFF control signal to the DAC 27.
  • the DAC 27 converts the on/off control signal input from the power supply control unit 25 into an analog signal on/off control signal.
  • the switch 31 turns on/off the application of the bias voltage from the power supply 29 to the auxiliary amplifier 6 according to the on/off control signal input from the DAC 27. For example, when the magnitude of the second envelope signal is the power between P0.5 dB and P3 dB of the main amplifier 5, the power supply control unit 25 compares the second envelope signal with the threshold value, and the result of the comparison. The switch 31 is controlled accordingly.
  • the Doherty amplifier ideally has the maximum efficiency when the output power is the preset backoff power, and the efficiency decreases as the output power increases from the backoff point, and finally the output saturation occurs. Power maximizes efficiency.
  • the backoff power is 6 dB
  • the efficiency of the Doherty amplifier depends on the efficiency of the main amplifier 5 at a backoff power higher than this.
  • the transmitter according to the third embodiment employs a method called envelope tracking in order to increase efficiency with a backoff power larger than a preset backoff power.
  • envelope tracking the bias voltage applied from the power supply 28 to the main amplifier 5 is modulated using the first envelope signal extracted from the first baseband signal.
  • the envelope extraction unit 23 extracts an envelope signal from the first baseband signal output from the first correction unit 1 and outputs the extracted envelope signal to the DAC 26.
  • the DAC 26 converts the envelope signal input from the envelope extraction unit 23 into an analog first envelope signal, and outputs the first envelope signal to the power supply modulation unit 30.
  • the power supply modulation unit 30 uses the first envelope signal to modulate the bias voltage applied from the power supply 28 to the main amplifier 5 so that the main amplifier 5 always operates in saturation. By doing so, the output power level can be determined by the bias voltage applied to the main amplifier 5, and high efficiency can be obtained.
  • High efficiency and high linearity can be obtained by always maintaining the amplitude and phase of the input signal of the main amplifier 5 when the main amplifier 5 is operating in saturation by adopting envelope tracking.
  • envelope tracking the amplitude and phase of the input signal fluctuate due to the parasitic component of the main amplifier 5 itself, the linearity decreases, and the frequency characteristic increases.
  • the first correction unit 1 corrects the amplitude and phase fluctuation components of the input signal in the main amplifier 5 in accordance with the size of the envelope of the first baseband signal. To do. For example, the first correction unit 1 corrects fluctuations in the amplitude and phase of the input signal from P0.5 dB, which is the maximum bias voltage applied to the main amplifier 5, to between P3 dB, and thereby a large envelope signal is obtained. On the other hand, the input power to the main amplifier 5 is kept constant. Further, in envelope tracking, since the frequency characteristic of the main amplifier 5 becomes large, the frequency characteristic is corrected by the CFIR 21 as in the second embodiment.
  • FIG. 14 is a block diagram showing a configuration of a modified example of the transmitter according to the third embodiment. 14, the same components as those of FIG. 13 are designated by the same reference numerals and the description thereof will be omitted.
  • the transmitter shown in FIG. 14 is a transmitter that amplifies and transmits a modulated wave signal, and includes a first correction unit 1A, a second correction unit 2A, a DAC 3, a DAC 4, a main amplifier 5, an auxiliary amplifier 6, and a line 7.
  • Line 8 combiner 9, line 10, feedback path 13, ADC 14, comparison unit 15, coefficient calculation unit 16, delay adjustment unit 17, DSP 18, distortion compensation unit 19, splitter 20, CFIR 21A, CFIR 22A, envelope extraction unit 23, envelope An extraction unit 24, a power supply control unit 25, a DAC 26, a DAC 27, a power supply 28, a power supply 29, a power supply modulation unit 30, and a switch 31 are provided.
  • the first correction unit 1A corrects the amplitude and phase of the first baseband signal using a plurality of correction coefficients or a plurality of tables.
  • the plurality of correction coefficients are a group of correction coefficients of amplitude and phase according to a change in temperature or a change in frequency of the first baseband signal.
  • the plurality of tables are a plurality of table data in which a plurality of correction coefficients are associated with a temperature change or a frequency change of the first baseband signal. For example, a plurality of correction coefficients or a plurality of tables are prepared in advance in a memory that can be read by the first correction unit 1A.
  • the second correction unit 2A corrects the amplitude and phase of the second baseband signal using a plurality of correction coefficients or a plurality of tables.
  • the plurality of correction coefficients are a group of correction coefficients of amplitude and phase according to a change in temperature or a change in frequency of the second baseband signal.
  • the plurality of tables are a plurality of table data in which a plurality of correction coefficients are associated with a temperature change or a frequency change of the second baseband signal. For example, the plurality of correction coefficients or the plurality of tables are prepared in advance in a memory that can be read by the second correction unit 2A.
  • the CFIR 21A is a first FIR filter that corrects the frequency characteristic of the output signal of the main amplifier 5 using a plurality of correction coefficients or a plurality of tables.
  • the plurality of correction coefficients are a correction coefficient group of frequency characteristics according to temperature changes or changes in the frequency of the first baseband signal.
  • the plurality of tables are a plurality of table data in which a plurality of correction coefficients are associated with a temperature change or a frequency change of the first baseband signal. For example, a plurality of correction coefficients or a plurality of tables are prepared in advance in a memory readable from the CFIR 21A.
  • the CFIR 22A is a second FIR filter that corrects the frequency characteristic of the output signal of the auxiliary amplifier 6 using a plurality of correction coefficients or a plurality of tables.
  • the plurality of correction coefficients are a correction coefficient group of frequency characteristics according to temperature changes or changes in the frequency of the second baseband signal.
  • the plurality of tables are a plurality of table data in which a plurality of correction coefficients are associated with a temperature change or a frequency change of the second baseband signal. For example, a plurality of correction coefficients or a plurality of tables are prepared in advance in a memory readable from the CFIR 22A.
  • the first correction unit 1A, the second correction unit 2A, the CFIR 21A, and the CFIR 22A are switched to a correction coefficient or a table corresponding to a temperature change or a change in the frequency of the baseband signal among a plurality of correction coefficients or a plurality of tables. Make a correction. With this, it is not necessary to calculate the correction coefficient corresponding to the temperature change or the frequency change of the baseband signal for each correction, and the calculation load in the correction can be reduced.
  • the transmitter according to the third embodiment has the components shown in FIGS. 13 and 14, and thus the transmitter according to the third embodiment has linearity while maintaining high efficiency.
  • the distortion compensation amount when the digital predistortion is applied to the amplifier is also improved.
  • the transmitter according to the present invention can be used for various communication systems because it can achieve both improvement of power efficiency in backoff power and improvement of linearity.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Transmitters (AREA)

Abstract

Dans la présente invention, un premier signal de bande de base et un second signal de bande de base qui ont été soumis à une distribution égale sont corrigés de manière à présenter des amplitudes et des phases mutuellement différentes, une telle correction étant effectuée en fonction de la taille de l'enveloppe de chaque signal. Ensuite, le premier signal de bande de base est entré dans un amplificateur principal (5), et le second signal de bande de base est entré dans un amplificateur auxiliaire (6).
PCT/JP2018/044220 2018-11-30 2018-11-30 Émetteur WO2020110298A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008078847A (ja) * 2006-09-20 2008-04-03 Hitachi Kokusai Electric Inc ドハティ増幅器
JP2012075081A (ja) * 2010-09-03 2012-04-12 Hitachi Kokusai Electric Inc 電力増幅装置
JP2015073270A (ja) * 2013-10-03 2015-04-16 フリースケール セミコンダクター インコーポレイテッド 信号調整を有する電力増幅器
US20160094187A1 (en) * 2014-09-29 2016-03-31 Freescale Semiconductor, Inc. Modifiable signal adjustment devices for power amplifiers and corresponding methods & apparatus
JP2018142798A (ja) * 2017-02-27 2018-09-13 住友電気工業株式会社 増幅装置及び通信機
JP2018157447A (ja) * 2017-03-17 2018-10-04 古河電気工業株式会社 増幅装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008078847A (ja) * 2006-09-20 2008-04-03 Hitachi Kokusai Electric Inc ドハティ増幅器
JP2012075081A (ja) * 2010-09-03 2012-04-12 Hitachi Kokusai Electric Inc 電力増幅装置
JP2015073270A (ja) * 2013-10-03 2015-04-16 フリースケール セミコンダクター インコーポレイテッド 信号調整を有する電力増幅器
US20160094187A1 (en) * 2014-09-29 2016-03-31 Freescale Semiconductor, Inc. Modifiable signal adjustment devices for power amplifiers and corresponding methods & apparatus
JP2018142798A (ja) * 2017-02-27 2018-09-13 住友電気工業株式会社 増幅装置及び通信機
JP2018157447A (ja) * 2017-03-17 2018-10-04 古河電気工業株式会社 増幅装置

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