JP2006129402A - Amplifier circuit and transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform amplification while maintaining high efficiency even if a peak factor of an input signal inputted to an amplifier circuit is great. <P>SOLUTION: If an input signal S is inputted to an amplifier circuit 100 of a LINC system, a predetermined envelope signal generating unit 101 generates two predetermined envelope signals S1, S2 and phase shifters 102a, 102b change phases to reduce a phase difference between the predetermined envelope signals S1, S2. Phase changed two predetermined envelope signals S1a, S2a are amplified by amplifiers 103a, 103b, respectively. Furthermore, amplified two predetermined envelope signals S1ag, S2ag are synthesized by a synthesizer circuit 104 and outputted as a synthetic signal Sag. At such a time, the phase shifters 102a, 102b change the phases to reduce the phase difference between the predetermined envelope signals S1, S2, thereby enlarging a minimum value of the synthetic signal Sag and also enlarging average output power. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an amplifier circuit used in a communication device and the like, and in particular, a final-stage amplifier circuit that amplifies a transmission signal of a transmission device used in a broadcasting field, a wireless communication field, and the like, and a transmitter including the amplifier circuit About.

  In recent years, transmission apparatuses used in the broadcast field, the wireless communication field, and the like are increasingly transmitting digitally modulated signals. Many of these transmission signals have been multi-valued, and information is placed in the amplitude direction of the signal, so that an amplifier circuit used in the transmission apparatus is required to have linearity. On the other hand, in order to reduce the power consumed by the transmission device, the amplifier circuit is also required to have high power efficiency. As described above, in order to achieve both the linearity of the amplifier circuit and the improvement of the power efficiency, various techniques for improving the distortion compensation and the power efficiency have been proposed. For example, a conventional amplifying circuit called a LINC (Linear Amplification with Nonlinear Components) system splits a transmission signal into two constant envelope signals, and has a high power efficiency. The linearity and the power efficiency are improved by synthesizing after amplification in (see, for example, Patent Document 1). Also disclosed is a technique for improving linearity and power efficiency by amplifying a transmission signal using a nonlinear high-efficiency transmission amplifier and performing quadrature modulation to obtain linearity (for example, Patent Documents) 2).

  FIG. 12 is a block diagram showing an example of a conventional LINC amplifier circuit. In the amplifier circuit 800 shown in FIG. 12, the constant envelope signal generation unit 801 generates two constant envelope signals S1 (t) and S2 (t) from the input signal S (t). Hereinafter, a process of generating two constant envelope signals S1 (t) and S2 (t) from the input signal S (t) will be described with mathematical expressions. The input signal S (t) and the two constant envelope signals S1 (t) and S2 (t) are obtained by the following equations (1), (2), and (3), respectively.

S (t) = V (t) · cos {ωct + φ (t)} (1)
S1 (t) = Vmax / 2 · cos {ωct + ψ (t)} (2)
S2 (t) = Vmax / 2 · cos {ωct + θ (t)} (3)
However,
ψ (t) = φ (t) + α (t)
θ (t) = φ (t) −α (t)
α (t) = cos ⁻¹ {V (t) / Vmax}
V (t) is the voltage of the input signal, Vmax is the maximum value of V (t), and ωc is the angular frequency of the carrier wave of the input signal.

  When S (t) is expressed by the above equation (1), if S1 (t) and S2 (t) are expressed by equations (2) and (3), S1 (t) and S2 (t) are amplitudes. A constant envelope signal with a constant direction.

FIG. 13 is a vector diagram of orthogonal plane coordinates of each signal in the LINC amplifier circuit shown in FIG. That is, this figure shows the operation of the constant envelope signal generation unit 801 in FIG. 12 using signal vectors on the orthogonal plane coordinates. As shown in FIG. 13, the input signal S (t) is represented by a vector sum of two constant envelope signals S1 (t) and S2 (t) having an amplitude of Vmax / 2. The two constant envelope signals S1 (t) and S2 (t) are amplified by the first amplifier 802a and the second amplifier 802b, respectively. At this time, if the gains of the first amplifier 802a and the second amplifier 802b are G, the output signals of the first amplifier 802a and the second amplifier 802b are G × S1 (t) and G × S2, respectively. (T). When these output signals are vector-synthesized by the synthesis circuit 803, an output signal G × S (t) can be obtained. In this way, the first amplifier 802a and the second amplifier 802b individually amplify the constant envelope signals S1 (t) and S2 (t), respectively, so that the first amplifier 802a and the second amplifier 802b Amplification can be performed in a non-linear region, that is, a saturation region. Therefore, the first amplifier 802a and the second amplifier 802b can be used with high power efficiency.
Japanese Patent Publication No. 6-22302 JP-A-8-163189

  However, in the conventional amplifier circuit, when the peak factor of the input signal S (t), which is the original signal, increases and the average amplitude decreases, the power efficiency in the amplifier circuit decreases. Further, when the peak factor value increases or the maximum output power decreases due to a change in the modulation condition of the input signal S (t), there is a problem that the power efficiency of the amplifier circuit decreases.

  The present invention has been made in view of the above points, and even if the peak factor of the input signal input to the amplifier circuit is large, the amplifier can be used while maintaining high efficiency, and the linearity can be maintained. An object of the present invention is to provide an amplifier circuit capable of amplifying an input signal to a desired level.

  The amplifier circuit of the present invention includes a constant envelope signal generating means for generating two constant envelope signals having different phases from an input signal, and two phase shifting means for individually changing the phases of the two constant envelope signals. And two amplifying means for individually amplifying the output signals of the two phase shifting means, and a synthesizing means for synthesizing the output signals of the two amplifying means, and the constant envelope signal generating means A first constant envelope signal having a positive phase and a second constant envelope signal having a negative phase with respect to the input signal are generated, and at least one of the two phase shifting means has a first A configuration is adopted in which the phase is changed in a direction to reduce the phase difference between the first constant envelope signal and the second constant envelope signal.

  In the amplifier circuit of the present invention, in the configuration of the invention, the two phase shift means are composed of a first phase shift means and a second phase shift means, and the first phase shift means is a first constant envelope. The phase of the line signal is changed in the minus direction, and the second phase shift means adopts a configuration in which the phase of the second constant envelope signal is changed in the plus direction.

  The amplifier circuit according to the present invention further includes means for calculating an average amplitude value or an average power value for calculating an average amplitude value of the input signal, and an average amplitude value or an average power value in addition to the configuration of the above invention. And a phase control means for controlling the phase change amount of the phase means.

  The amplifier circuit according to the present invention further includes means for calculating the maximum amplitude value of the input signal or means for calculating the maximum power value, and the ratio of the average amplitude value to the maximum amplitude value, in addition to the configuration of the above invention. Or a means for calculating a ratio between the average power value and the maximum power value.

  In addition to the configuration of the present invention, the amplifier circuit of the present invention further includes an amplitude calculation unit that calculates an amplitude value of an input signal, and an amplitude value calculated by the amplitude calculation unit exceeds a predetermined threshold value. The voltage control means for controlling the bias voltage of the amplification means is adopted.

  In addition to the configuration of the invention, the amplifier circuit of the present invention further employs a configuration in which a peak suppression unit for suppressing the amplitude peak value of the input signal is provided upstream of the amplitude calculation unit. Furthermore, the present invention can provide a transmitter including the amplifier circuit of each of the above inventions.

  According to the amplifier circuit of the present invention, two constant envelope signals are generated from an input signal, and the phase of each constant envelope signal is individually changed and amplified to generate a combined signal. At this time, one of the two phase shifting means (first phase shifting means) changes the phase of the first constant envelope signal in the positive direction to the negative direction, The phase shift means (second phase shift means) changes the phase of the second constant envelope signal in the minus direction in the plus direction. As a result, the phase of the two constant envelope signals is shifted by the first phase shift means and the second phase shift means so as to reduce the phase difference, so that the minimum value of the combined signal can be increased. And the average power of the output signal can be increased. Therefore, it is possible to improve the power efficiency of the amplifier circuit using the LINC method.

  In addition, according to the amplifier circuit of the present invention, a function for calculating the average amplitude or average power of the input signal is further provided in the previous stage for generating the constant envelope signal, and two functions are provided depending on the magnitude of the average amplitude or average power. The amount of phase change of the constant envelope signal is controlled. As a result, even when the peak factor increases due to changes in the modulation conditions of the input signal and the average output power decreases, the phase of the constant envelope signal is changed so that the average output power increases. A decrease can be prevented.

  Further, according to the amplifier circuit of the present invention, the function of calculating the maximum amplitude value or the maximum power value of the input signal and the ratio of the maximum amplitude value and the average amplitude value or the maximum power value before the generation of the constant envelope signal And the function of calculating the ratio of the average power value, and the phase change amount of the two constant envelope signals is controlled according to the maximum amplitude value or the maximum power value. As a result, even if the ratio between the maximum amplitude value and the average amplitude value or the ratio between the maximum power value and the average power value increases due to a change in the modulation condition of the input signal, the constant envelope signal is increased so that the average amplitude is increased. Since the phase is changed, it is possible to prevent a reduction in efficiency of the amplifier circuit.

  In addition, according to the amplifier circuit of the present invention, the function of calculating the amplitude value of the input signal is further provided before the generation of the constant envelope signal, and the bias voltage of the amplification means is controlled according to the magnitude of the amplitude value. ing. As a result, even if the peak portion of the waveform of the input signal is reduced by phase control, the amplitude of the constant envelope signal can be increased and the distortion of the composite signal can be corrected by increasing the bias voltage of the amplification means. Therefore, it is possible to improve the linearity of the amplifier circuit and prevent the communication quality from deteriorating.

  In addition, according to the amplifier circuit of the present invention, since the function for suppressing the amplitude peak value of the signal is further added to the preceding stage of the function for calculating the amplitude value of the input signal, the amplitude peak value of the input signal is suppressed. Since the amount of change in the bias voltage of the amplifying means can be reduced, the power supply efficiency can be improved.

  That is, according to the present invention, it is possible to realize an amplifier circuit that satisfies both the maintenance of high linearity and the improvement of power efficiency. For this reason, in the LINC system amplifier circuit, even if the peak factor of the input signal S increases or the average amplitude decreases, there is no possibility that the power efficiency in the amplifier circuit decreases. A suitable wireless transmission / reception apparatus can be constructed.

  The amplifier circuit of the present invention generates two constant envelope signals from an input signal which is an original signal, and amplifies each constant envelope signal with two amplifiers and then combines them to synthesize a desired transmission signal. This is a LINC-type amplifier circuit to be obtained. That is, the phase of at least one of the two constant envelope signals is changed by the phase shift means. Preferably, the phases of the two constant envelope signals are shifted to opposite phases (that is, a positive phase and a negative phase). Then, the two constant envelope signals whose phases are shifted are individually amplified and synthesized. As a result, the average power of the output signal can be increased and the power loss in the amplifier circuit can be reduced to improve the power efficiency.

  Hereinafter, some embodiments of an amplifier circuit according to the present invention will be described in detail with reference to the drawings. In the drawings used in the embodiments described below, the same components are denoted by the same reference numerals, and redundant description will be omitted as much as possible.

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 1 of the present invention. The amplifier circuit 100 includes a constant envelope signal generation unit 101 that generates two constant envelope signals S1 and S2 from an input signal S, and two constant envelope signals S1 and S2 output from the constant envelope signal generation unit 101. The phase shifters 102a and 102b that individually change the phases of the phase shifters, and the constant envelope signals S1a and S2a after the phase change output from each of the phase shifters 102a and 102b are individually received. A final stage amplifier 103a and amplifier 103b to be amplified, and a synthesis circuit 104 that synthesizes the constant envelope signals S1ag and S2ag after amplification output from the amplifier 103a and amplifier 103b to generate and output a synthesized signal Sag. It becomes the composition.

  The constant envelope signal generation unit 101 is orthogonal to a digital signal processing circuit such as an ASIC (Application Specific Integrate Circuit) or an FPGA (Field Programmable Gate Array) and a D / A converter. It can be realized with a modulator. The phase shifter 102a and the phase shifter 102b can be realized by a hybrid phase shifter using a microstrip line, for example. Furthermore, the amplifier 103a and the amplifier 103b can be realized by, for example, FETs or transistors. The synthesis circuit 104 can be realized by, for example, a Wilkinson type synthesis circuit or a resistance synthesis circuit made of a microstrip line.

  Next, the operation of the amplifier circuit 100 configured as shown in FIG. 1 will be described. First, the constant envelope signal generation unit 101 generates the constant envelope signals S1 and S2 from the input signal S that is the original signal, and individually transmits them to the phase shifter 102a and the phase shifter 102b. Hereinafter, the process of generating the two constant envelope signals S1 and S2 from the input signal S will be described using mathematical expressions using the time function (t). That is, the input signal S (t) and the two constant envelope signals S1 (t) and S2 (t) are obtained by the following equations (4), (5), and (6), respectively.

S (t) = V (t) · cos {ωct + φ (t)} (4)
S1 (t) = Vmax / 2 · cos {ωct + ψ (t)} (5)
S2 (t) = Vmax / 2 · cos {ωct + θ (t)} (6)
However,
ψ (t) = φ (t) + α (t)
θ (t) = φ (t) −α (t)
α (t) = cos ⁻¹ {V (t) / Vmax}
Here, V (t) is the voltage of the input signal, Vmax is the maximum value of V (t), and ωc is the angular frequency of the carrier wave of the input signal.

  In the following description, the time function (t) is omitted, and the vector relationship is described by representing the input signal as S and the two constant envelope signals as S1 and S2, respectively. FIG. 2 is a vector diagram showing the relationship between the input signal and two constant envelope signals in the amplifier circuit of the first embodiment shown in FIG. 2A is a vector diagram in which the input signal S is separated into two constant envelope signals S1 and S2, and FIG. 2B is a phase shift of the constant envelope signal S1 by −β °. FIG. 2C is a vector diagram in which the constant envelope signal S2ag amplified by shifting the phase of the amplified constant envelope signal S1ag and the constant envelope signal S2 by + β °, and FIG. 2C shows the constant envelope when the phase is not changed. FIG. 2D is a vector diagram showing a range where the constant envelope signal S1ag and the constant envelope signal S2ag are present when the phase is changed. is there.

  The vector diagram of FIG. 2A represents the above equations (4), (5), and (6) as vectors. Here, regarding the two constant envelope signals S1 and S2, when the first constant envelope signal is S1 and the second constant envelope signal S2, the phase shifter to which the first constant envelope signal S1 is input. 102a changes the phase of the first constant envelope signal S1 by β ° in the minus direction, and the phase shifter 102b to which the second constant envelope signal S2 is input is the phase of the second constant envelope signal S2. Is changed by β ° in the positive direction. The first constant envelope signal S1a and the second constant envelope signal S2a that have been changed are input to the amplifiers 103a and 103b at the final stage. The first constant envelope signal S1a and the second constant envelope signal S2a after the phase change at that time can be expressed by the following equations (7) and (8).

S1a = Vmax / 2 · cos (ωift + ψ (t) −β) (7)
S2a = Vmax / 2 · cos (ωift + θ (t) + β) (8)
However, ωift is the angular frequency of the carrier wave of the input signal to the phase shifters 102a and 102b.

  Further, the first constant envelope signal S1a and the second constant envelope signal S2a after the phase change are amplified by the amplifiers 103a and 103b at the final stage, and then synthesized by the synthesis circuit 104 and output. At this time, the first constant envelope signal S1ag amplified by the amplifier 103a, the second constant envelope signal S2ag amplified by the amplifier 103b, and the synthesized signal Sag synthesized by the synthesis circuit 104 are respectively expressed by the following equations (9): ), Formula (10), and formula (11).

S1ag = G · Vmax / 2 · cos ((ωrft + ψ (t) −β)) (9)
S2ag = G · Vmax / 2 · cos ((ωrft + θ (t) + β)) (10)
Sag = G · V (t) cos {ωrft + φ ′ (t)} (11)

  The improvement in efficiency in the final stage amplifiers 103a and 103b at this time will be described using a vector diagram and a time axis waveform. FIG. 2B represents the above equations (9), (10), and (11) as a vector diagram. When the phase of each constant envelope signal changes to -β and + β as shown in FIG. 2B, the first constant envelope signal S1ag and the second constant envelope after amplification by changing the phase. The existence range of the vector of the line signal S2ag is as shown in FIG. Then, the minimum value Sagmin and the maximum value Sagmax of the synthesized signal Sag obtained by synthesizing the first constant envelope signal S1ag and the second constant envelope signal S2ag after amplification by changing the respective phases to -β and + β are: The following equations (12) and (13) are obtained.

Sagmin = Vmax · cos {π / 2−β} (12)
Sagmax = Vmax (13)

  As can be seen from the above equations (12) and (13), the maximum value Sagmax of the combined signal Sag is not different from the maximum value Smax of the original input signal S, but the minimum value Sagmin of the combined signal Sag is the original input. It can be seen that the signal S is always larger than the minimum value Smin. The vector existence range when the phases of the first constant envelope signal S1 and the second constant envelope signal S2 are not changed is as shown in FIG.

  FIG. 3 is a diagram showing signal waveforms on the time axis when the phase of the constant envelope signal is not changed and when the phase is changed in Embodiment 1 of the present invention. That is, the diagram on the left side of FIG. 3 shows a range in which the first constant envelope signal S1 and the second constant envelope signal S2 exist when the phase of the constant envelope signal is not changed as shown in FIG. 3 shows the waveform of the synthesized signal S on the time axis, and the diagram on the right side of FIG. 3 shows the first constant envelope signal S1ag when the phase of the constant envelope signal is changed as shown in FIG. The waveform of the combined signal Sag within the range where the second constant envelope signal S2ag exists is shown on the time axis.

  In other words, the waveform shown on the left side of FIG. 3 is the waveform of the synthesized signal S after vector synthesis when the phases of the constant envelope signal S1 and the constant envelope signal S2 are not changed, and the waveform shown on the right side of FIG. It is a waveform of the synthesized signal Sag after vector synthesis when the phases of the constant envelope signal S1 and the constant envelope signal S2 are changed.

  As shown in the waveform diagram on the right side of FIG. 3, when the phase of the constant envelope signal is changed, the maximum value of the signal does not change, but the average amplitude is the waveform when the phase of the constant envelope signal is not changed ( It is larger than the waveform on the left. In this way, if the average power of the combined signal is increased by changing the phase of the constant envelope signal, the power efficiency of the amplifier circuit is improved as a result.

  As described above, according to the amplifier circuit of the first embodiment of the present invention, the average power of the output signal is increased by changing the phase of the two constant envelope signals in the direction of decreasing the phase difference. As a result, the power efficiency of the amplifier circuit can be improved.

  In the above description, the basic amplifier circuit block diagram as shown in FIG. 1 has been described. However, an amplifier circuit may be configured using a quadrature modulator and a mixer. FIG. 4 is a block diagram showing a specific configuration of the amplifier circuit according to Embodiment 1 of the present invention. In FIG. 4, an amplifier circuit is realized using a quadrature modulator and a mixer.

In FIG. 4, an amplifier circuit 100 uses baseband IQ signals as input signals S _I and S _Q, and performs quadrature modulation to generate S1 IQ signals (S _1I and S _1Q ) and S2 IQ signals that become constant envelope signals. A constant envelope signal IQ generation unit 201 that generates (S _2I , S _2Q ), quadrature modulators 202 a and 202 b that perform orthogonal modulation processing on an output signal from the constant envelope signal IQ generation unit 201, and quadrature modulation After that, the phase shifters 102a and 102b for changing the phase of the constant envelope signal, the mixers 203a and 203b for synthesizing the two constant envelope signals after changing the phase, and up-converting to the radio frequency, the final stage Amplifiers 103a and 103b for amplifying the signal, a synthesis circuit 104 for synthesizing the constant envelope signal after amplification, and local oscillators 204 and 206.

In the amplification circuit 100 configured as described above, the constant envelope signal IQ generation unit 201 performs the S1 IQ signal (S _1I , S _1Q) that becomes a constant envelope signal when orthogonally modulated from the baseband IQ signal of the input signal S. ) And S2 IQ signals (S _2I , S _2Q ), and quadrature modulation of these signals by the quadrature modulators 202a and 202b, the phase shifters 102a and 102b change the phase of the constant envelope signal. Further, the signals are up-converted to the radio frequency by the mixers 203a and 203b, amplified by the amplifiers 103a and 103b at the final stage, and then synthesized by the synthesis circuit 104 to output the output signal _SRF .

  In the case of this amplifier circuit, the phase shifters 102a and 102b are provided between the quadrature modulators 202a and 202b and the mixers 203a and 203b. However, the present invention is not limited to this, and the quadrature modulators 202a and 202b and the local oscillator are not limited thereto. The phase shifters 205a and 205b may be provided between 204, and although not shown in the figure, the same effect can be obtained by providing a phase shifter between the mixers 203a and 203b and the local oscillator 206. It is done.

  Further, the same effect as described above can be obtained even if the constant envelope signal S1 and S2 are phase-controlled in the constant envelope signal generator 101 in FIG. 1 and the constant envelope signal IQ generator 201 in FIG. . Further, in the above description, the phase change amount is set to −β in the constant envelope signal S1, the constant envelope signal S2 is set to + β, and the absolute value of the phase change amount is set to the constant envelope signal S1 and the constant envelope signal S2. Although the same, the same effect as described above can be obtained even if the phase change amount is different between the constant envelope signal S1 and the constant envelope signal S2.

<Embodiment 2>
FIG. 5 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 2 of the present invention. The second embodiment shown in FIG. 5 is different from the amplifier circuit 100 of the first embodiment shown in FIG. 1 in terms of an average amplitude calculation unit 301 that calculates an average amplitude value of the input signal S, and the average amplitude value. A phase control unit 302 that controls the amount of phase change in the phase shifter 102 a and the phase shifter 102 b is added to the preceding stage of the constant envelope signal generation unit 101.

  The average amplitude calculation unit 301 and the phase control unit 302 in FIG. 5 are realized by a digital signal processing circuit such as an ASIC or FPGA, for example. In FIG. 5, first, when the input signal S is input to the average amplitude calculation unit 301, the average amplitude of the input signal S is calculated by the average amplitude calculation unit 301. The average amplitude value information is transmitted from the average amplitude calculation unit 301 to the phase control unit 302, and the phase change amount β is determined according to the magnitude of the average amplitude value and transmitted to the phase shifters 102a and 102b. .

  On the other hand, the input signal S, which is the original signal, is input to the constant envelope signal generation unit 101 of the amplifier circuit 100, and the same operation as in the first embodiment is performed. Here, the average amplitude calculation unit 301 periodically or always calculates the average amplitude value of the input signal S for a certain period of time. When the average amplitude value of the input signal S becomes small, information indicating that the average amplitude value has decreased is transmitted from the average amplitude calculation unit 301 to the phase control unit 302. Thereby, the phase control unit 302 performs an operation to increase the phase change amount β.

  As described above, according to the second embodiment of the present invention, the average amplitude calculation unit 301 in the previous stage of the amplifier circuit 100 in FIG. 5 calculates the average amplitude value of the input signal S, and the phase control is performed from the information. The unit 302 controls the phase change amount of the phase shifter 102 in the amplifier circuit 100. As a result, when the average amplitude value of the original input signal S becomes small, a decrease in power efficiency can be prevented by increasing the phase change amount β.

<Embodiment 3>
FIG. 6 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 3 of the present invention. The third embodiment shown in FIG. 6 is the maximum amplitude for calculating the maximum amplitude value of the input signal S for the amplifier circuit 100 and the average amplitude calculation unit 301 and the phase control unit 302 of the second embodiment shown in FIG. A calculation unit 401 and an average amplitude-to-maximum amplitude ratio calculation unit 402 are configured to be added to the previous stage of the constant envelope signal generation unit 101.

  The maximum amplitude calculation unit 401 and the average amplitude-to-maximum amplitude ratio calculation unit 402 in FIG. 6 are realized by digital signal processing circuits such as ASIC and FPGA, for example. In FIG. 6, first, when the input signal S is input to the average amplitude calculation unit 301, the average amplitude of the input signal S is calculated by the average amplitude calculation unit 301. Next, when the input signal S is input to the maximum amplitude calculation unit 401, the maximum amplitude calculation unit 401 calculates the maximum amplitude value of the input signal S. Then, the average amplitude information and the maximum amplitude value information are respectively transmitted to the average amplitude-to-maximum amplitude ratio calculation unit 402, the ratio between the average amplitude and the maximum amplitude is calculated, and the value is transmitted to the phase control unit 302. The phase control unit 302 determines the phase change amount β according to the magnitude of the ratio and transmits it to the phase shifters 102a and 102b. Thereby, the phase control unit 302 performs an operation to optimize the phase change amount β. At this time, the average amplitude calculation unit 301 and the maximum amplitude calculation unit 401 regularly calculate the average amplitude value and the maximum amplitude value of the input signal S in a certain time period, or always calculate the average amplitude value and the maximum amplitude value of the original input signal S. When the average amplitude value with respect to the maximum amplitude value decreases, an operation is performed to increase the phase change amount β.

  As described above, according to the third embodiment of the present invention, the maximum amplitude calculation unit 401 in the previous stage of the amplifier circuit 100 in FIG. 6 calculates the maximum amplitude value of the original input signal S, and the average amplitude to maximum amplitude ratio is calculated. The calculation unit 402 calculates the ratio between the average amplitude and the maximum amplitude, and the phase control unit 302 controls the phase change amount of the phase shifter 102 in the amplifier circuit 100 from the information. And when the average amplitude value with respect to the maximum amplitude value of the input signal S becomes small, a decrease in power efficiency can be prevented by increasing the phase change amount β.

<Embodiment 4>
FIG. 7 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 4 of the present invention. The fourth embodiment shown in FIG. 7 is different from the amplifier circuit 100 of the first embodiment shown in FIG. 1 in that the amplitude calculation unit 501 calculates the amplitude value of the input signal S and an amplifier according to the magnitude of the amplitude value. A voltage control unit 502 that controls the bias voltages of 103a and 103b is added to the preceding stage of the constant envelope signal generation unit 101. That is, the voltage control unit 502 is configured to control the bias voltages of the amplifiers 103a and 103b when the amplitude value calculated by the amplitude calculation unit 501 exceeds a predetermined threshold value. 7 is realized by a digital signal processing circuit such as ASIC or FPGA, for example.

  FIG. 8 is a diagram showing a waveform of the modulation signal on the time axis and the waveform of the bias power supply according to Embodiment 4 of the present invention, FIG. 8A shows the original signal waveform, and FIG. FIG. 8C shows the waveform of the bias voltage and the modulation signal in the amplifier circuit of FIG. 7. FIG. 8C shows the waveform of the bias voltage and the modulation signal in the phase-controlled amplifier circuit. That is, in the amplifier circuit 100 according to the first embodiment described above, when the original signal as shown in FIG. 8A is input, the output signal has a certain amplitude as shown in FIG. Above the value, the amplitude is suppressed and distortion occurs. Such an amplitude threshold is determined by the phase control amount β. At this time, the bias voltages of the amplifiers 103a and 103b are constant.

  On the other hand, in the amplifier circuit according to the fourth embodiment shown in FIG. 7, the amplitude value of the input signal S is calculated by the amplitude calculation unit 501. Then, when the threshold value determined by the phase control amount β is exceeded from the amplitude information of the calculation result, the voltage control unit 502 sets the bias voltage of the amplifiers 103a and 103b to the amplitude value as shown in FIG. Increase according to. As a result, the waveform of the output signal is a waveform in which the signal waveform at the peak value approximates the original signal (that is, the input signal), as shown in FIG.

  As described above, according to the fourth embodiment of the present invention, as shown in FIG. 7, the amplitude calculation unit 501 in the previous stage of the amplifier circuit 100 calculates the amplitude value of the original signal and uses the information as the voltage control unit. To 502. As a result, the voltage control unit 502 controls the bias voltage of the amplifiers 103a and 103b from the amplitude information, so that the distortion of the output signal can be reduced and the linearity can be improved. It can be made smaller. In the fourth embodiment, bias control is performed by providing a threshold value corresponding to the phase control amount β. However, the same effect can be obtained by performing voltage control according to amplitude without providing a threshold value.

<Embodiment 5>
FIG. 9 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 5 of the present invention. In the fifth embodiment shown in FIG. 9, a peak suppression unit 601 for suppressing the amplitude peak value of the input signal is added to the previous stage of the amplitude calculation unit 501 with respect to the configuration of the fourth embodiment shown in FIG. It is.

  FIG. 10 is a diagram showing the waveform of the modulation signal on the time axis and the waveform of the bias power supply according to the fifth embodiment of the present invention, and FIG. 10A shows the waveform of the bias voltage and the modulation signal in the phase-controlled amplifier circuit. FIG. 10B shows the waveform of the modulation signal that has passed through the peak suppression unit 601, and FIG. 10C shows the waveform of the bias voltage and the modulation signal in the amplifier circuit of FIG.

  That is, in the amplifier circuit 100 according to the first embodiment, when an original signal as shown in FIG. 8A is input, the output signal has a certain amplitude as shown in FIG. When the value exceeds the value, the amplitude is returned and output. Further, the larger the peak amplitude of the original signal, the smaller the output amplitude of the folded portion. Therefore, in the amplifier circuit according to the fourth embodiment shown in FIG. 7, when the threshold value determined by the phase control amount β is exceeded from the amplitude information of the original signal, the voltage control unit 502 causes the bias of the amplifiers 103a and 103b to be biased. Although the voltage is increased, it is necessary to increase the bias voltage as the amplitude of the distorted portion is smaller. As a result, the power supply efficiency is lowered.

  Therefore, in the amplifier circuit of the fifth embodiment shown in FIG. 9, as shown in FIG. 10B, the amplitude value of the peak of the input signal S is converted into a return amplitude determined by the phase control amount β by the peak suppression unit 601. Suppressed below the value and output to the amplitude calculator 501. Since the subsequent operation is the same as that of the fourth embodiment, when the threshold value determined by the phase control amount β is exceeded, the voltage control unit 502 sets the bias voltages of the amplifiers 103a and 103b in FIG. As shown in FIG. 4, the value is increased according to the amplitude value. Thereby, as shown in FIG. 10C, the waveform of the output signal becomes a waveform in which the signal waveform at the peak value approximates the original signal (that is, the input signal). At this time, the change amount of the bias voltage in the voltage control unit 502 is smaller than the change amount of the fourth embodiment, so that the power supply efficiency can be improved.

  As described above, according to the fifth embodiment of the present invention, the peak suppression unit 601 suppresses the peak amplitude value of the original signal (input signal) with the circuit configuration shown in FIG. Since the amount of change in the bias voltage at 103a and 103b can be reduced, the power supply efficiency can be improved.

<Embodiment 6>
FIG. 11 is a block diagram showing a configuration of a radio transmission / reception apparatus according to Embodiment 6 of the present invention. That is, according to the present invention, the wireless transmission / reception device 700 can be constructed using the amplifier circuit 100 of each of the above inventions. A wireless transmission / reception apparatus 700 according to Embodiment 6 includes an amplifier circuit 100, an antenna 701, an antenna duplexer 702, a wireless reception circuit 703, and a modem unit 704.

  The antenna 701 corresponds to an antenna that transmits or receives a radio signal. The antenna duplexer 702 is an antenna sharing unit that shares one antenna for transmission and reception. The antenna duplexer 702 outputs a signal output from the amplifier circuit 100 to the antenna 701 and also a signal received by the antenna 701 to the radio reception circuit 703. Output. The wireless reception circuit 703 is a wireless reception circuit that extracts a desired reception signal from the signal output from the antenna duplexer 702. For example, a low noise amplifier, a mixer that performs frequency conversion, a filter, a variable gain amplifier, and an A / D conversion It is composed of a container.

  The modem unit 704 performs signal modulation in order to wirelessly transmit a signal such as audio, video, or data. In addition, modulation / demodulation means for demodulating a signal received wirelessly into a signal such as audio, video, or data is provided. The amplifier circuit 100 is the amplifier circuit shown in the first to fifth embodiments. The radio receiving apparatus 700 according to the sixth embodiment can improve power efficiency in the amplifier circuit as a configuration using the amplifier circuit described in each of the above-described embodiments in order to amplify the transmission signal. Thus, according to the sixth embodiment, the power efficiency of the LINC-type amplifier circuit mounted on the wireless transmission / reception device can be improved. Therefore, the wireless transmission / reception device according to the sixth embodiment is a base station device. And can be applied to communication terminal devices.

  As described above, since the amplifier circuit according to the present invention can achieve high linearity and high efficiency, the amplifier circuit can be used for a wireless transmission / reception apparatus used in the broadcasting field, the wireless communication field, and the like. The present invention can also be applied to a device and a communication terminal device.

The block diagram which shows the structure of the amplifier circuit which concerns on Embodiment 1 of this invention. The vector diagram which shows the relationship between the input signal and two constant envelope signals in the amplifier circuit shown in FIG. In Embodiment 1 of this invention, the figure which shows the signal waveform in the time-axis when not changing the phase of a constant envelope signal, and changing it The block diagram which shows the concrete structure of the amplifier circuit which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the amplifier circuit which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the amplifier circuit which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the amplifier circuit which concerns on Embodiment 4 of this invention. Waveform of modulation signal on time axis and waveform of bias power supply according to embodiment 4 of the present invention Block diagram showing a configuration of an amplifier circuit according to a fifth embodiment of the present invention Waveform of modulation signal on time axis and waveform of bias power supply according to embodiment 5 of the present invention The block diagram which shows the structure of the radio | wireless transmitter / receiver which concerns on Embodiment 6 of this invention. The block diagram which shows the structure of the conventional LINC system amplifier circuit The figure which shows the vector of the orthogonal plane coordinate of each signal in the conventional LINC system amplifier circuit

Explanation of symbols

100, 800 Amplifier circuit 101, 801 Constant envelope signal generator 102a, 102b Phase shifter 103a, 103b, 802a, 802b Amplifier 104, 803 Synthesizer circuit 201 Constant envelope signal IQ generator 202a, 202b Quadrature modulator 203a, 203b Mixer 204, 206 Local oscillator 205a, 205b Phase shifter 301 Average amplitude calculator 302 Phase controller 401 Maximum amplitude calculator 402 Average amplitude to maximum amplitude ratio calculator 501 Amplitude calculator 502 Voltage controller 601 Peak suppressor 700 Wireless transmission / reception Device 701 Antenna 702 Antenna duplexer 703 Radio reception circuit 704 Modulator / Demodulator

Claims (7)

Constant envelope signal generating means for generating two constant envelope signals having different phases from the input signal;
Two phase shifting means for individually changing the phase of each of the two constant envelope signals;
Two amplifying means for individually amplifying the output signals of the two phase shifting means;
Combining means for combining the output signals of the two amplifying means,
The constant envelope signal generation means includes a first constant envelope signal that is in a positive phase with respect to the input signal, and a second constant envelope signal that is in a negative direction with respect to the input signal. Produces
At least one of the two phase shifting means changes the phase in a direction to reduce the phase difference between the first constant envelope signal and the second constant envelope signal. The two phase shifting means comprises a first phase shifting means and a second phase shifting means,
The first phase shifting means changes the phase of the first constant envelope signal in the negative direction,
2. The amplifier circuit according to claim 1, wherein the second phase shift unit changes the phase of the second constant envelope signal in a plus direction. Means for calculating an average amplitude value or average power value of the input signal;
The amplifier circuit according to claim 1, further comprising: a phase control unit that controls a phase change amount of the phase unit according to the average amplitude value or the average power value. Means for calculating a maximum amplitude value or a maximum power value of the input signal;
4. The amplifier circuit according to claim 3, further comprising means for calculating a ratio between the average power value and the maximum amplitude value or a ratio between the average power value and the maximum power value. Amplitude calculating means for calculating an amplitude value of the input signal;
3. The amplifier circuit according to claim 1, further comprising a voltage control unit configured to control a bias voltage of the amplification unit when the amplitude value calculated by the amplitude calculation unit exceeds a predetermined threshold value. .   6. The amplifier circuit according to claim 5, further comprising peak suppression means for suppressing an amplitude peak value of the input signal before the amplitude calculation means.   A transmitter comprising the amplifier circuit according to any one of claims 1 to 6.

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