JP2006314087A - Amplifier circuit and radio equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a LINC (linear amplification with nonlinear components) type amplifier circuit capable of enhancing the power efficiency of an amplifier, while performing transmission power control over a wide dynamic range. <P>SOLUTION: Fixed envelope signals S1 and S2 generated by a fixed envelope signal generating part 102 are amplified by amplifiers 104a and 104b. When the amplified fixed envelope signals S1 and S2 by transmission power that is equal to and greater than a certain threshold are output, first selection circuits 105a and 105b and second selection circuits 108a and 108b select the paths of second amplifiers 106a and 106b to transmit the amplified fixed envelope signals S1 and S2, and a synthesis circuit 109 synthesizes the signals S1 and S2 and outputs a signal S. Also, when the fixed envelope signals S1 and S2 are output by transmission power that is not greater than the certain threshold, the first selection circuits 105a and 105b and the second selection circuits 108a and 108b are controlled to select the paths of lines 107a and 107b having no amplifier, and a signal S obtained by synthesizing the signals S1 and S2 by the synthesis circuit 109 is outputted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a final-stage amplifier circuit and the like for amplifying a transmission signal of a transmission device used for wireless communication, broadcasting, and the like, and in particular, a LINC that outputs a synthesized signal after branching and amplifying an input signal into two. The present invention relates to a (Linear Amplification with Nonlinear Components) type amplifier circuit and a radio apparatus using the amplifier circuit.

  In recent years, transmission apparatuses used for communication and broadcasting frequently transmit digitally modulated signals. Many of these signals are multi-valued and information is placed in the amplitude direction. Therefore, the amplifier circuit used in the transmission apparatus is required to have linearity. On the other hand, high power efficiency is also required for the amplifier circuit in order to reduce the power consumption of the transmission apparatus. Therefore, various methods relating to distortion compensation and efficiency improvement have been proposed in order to achieve both linearity and power efficiency improvement in the amplifier circuit. For example, in a conventional amplifier circuit called a LINC method, a transmission signal is branched into two constant envelope signals, amplified by a power-efficient nonlinear amplifier, and then combined to obtain linearity and high efficiency. (For example, refer patent document 1). Also disclosed is a technique for amplifying a transmission modulation wave with amplitude fluctuation with a nonlinear and high-efficiency amplifier, and using the amplitude waveform as a power source of the amplifier to achieve linearity and high efficiency (for example, patents). Reference 2).

  FIG. 10 is a block diagram showing a configuration of a conventional LINC amplifier circuit. In the amplifier circuit 10 shown in FIG. 10, the constant envelope signal generation unit 11 generates two constant envelope signals S1 (t) and S2 (t) from the input signal S (t). These constant envelope signals S1 (t) and S2 (t) will be described using mathematical expressions. When the input signal S (t) is expressed by the following equation (1), if the two constant envelope signals S1 (t) and S2 (t) are expressed by the equations (2) and (3), The constant envelope signals S1 (t) and S2 (t) are constant envelope signals having a constant amplitude direction.

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)
Where Vmax is the maximum value of V (t), ωc is the angular frequency of the carrier wave of the input signal,
ψ (t) = φ (t) + α (t)
θ (t) = φ (t) −α (t)
And

  FIG. 11 is a diagram showing a signal of the amplifier circuit according to the conventional LINC system shown in FIG. That is, FIG. 11 is a vector diagram showing the operation of the constant envelope signal generation unit 11 of FIG. 10 using signal vectors on the orthogonal plane coordinates. As shown in FIG. 11, it can be seen that 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. As shown in FIG. 10, the two constant envelope signals S1 (t) and S2 (t) are amplified by the amplifier 12a and the amplifier 12b, respectively. At this time, if the gains of the amplifier 12a and the amplifier 12b are G, the output signals of the amplifier 12a and the amplifier 12b are G × S1 (t) and G × S2 (t), respectively. When these signals are vector-synthesized by the synthesis circuit 13, an output signal G × S (t) can be obtained. Here, the amplifier 12a and the amplifier 12b each amplify the constant envelope signal. Therefore, it is possible to amplify in the nonlinear region of the amplifier 12a and the amplifier 12b, that is, the saturation region, so that the power efficiency of the amplifier 12a and the amplifier 12b can be increased.

Also, in recent wireless communication, a TDMA-TDD (Time Division Multiple Access-Time Division Duplex) wireless transmission device attenuates the output level on the transmission side when it is determined that the reception power on the reception side is large to some extent. Sometimes. Further, in a CDMA (Code Division Multiple Access) type wireless transmission apparatus, transmission power control (TPC: Transmit Power Control) is performed on each terminal so that the signal level of each terminal is constant on the receiving side. is there. FIG. 12 is a block diagram showing a configuration of a conventional transmission circuit that performs transmission power control. That is, conventionally, a transmission circuit as shown in FIG. 12 is used to control the output level of the transmitter. The transmission circuit 20 of the wireless transmission device shown in FIG. 12 includes a baseband unit 21, a variable attenuator 22, a frequency converter 23, an amplifier 24, a bandpass filter 25, and an antenna 26. In such a transmission circuit 20, the transmission power output from the antenna 26 is controlled with high efficiency by controlling the attenuation amount of the variable attenuator 22 from the baseband unit 21 in accordance with the power level to be transmitted.
Japanese Patent Publication No. 06-22302 Japanese Patent Laid-Open No. 08-163189

  However, if a LINC-type amplifier circuit as shown in FIG. 10 is configured by using two transmission circuits as shown in FIG. 12, the power efficiency of the amplifier is reduced when outputting with a small level of transmission power. End up. That is, when outputting transmission power from low power to high power, the power efficiency of the amplifier decreases in the low power region. Therefore, transmission power cannot be controlled in a wide dynamic range without reducing the power efficiency of the amplifier.

  The present invention has been made in view of such a point, and an object of the present invention is to provide an amplifier circuit capable of maintaining good linearity and high power efficiency even when transmission power control of a wide dynamic range is performed.

  The amplifier circuit according to the present invention includes a constant envelope signal generation unit that generates two constant envelope signals from an input signal, a first amplification unit that individually amplifies the two constant envelope signals, and the first A first selection unit and a second selection unit that selectively switch the output paths of the amplification units to two paths having different gains; and a second amplification unit present in at least one of the two paths. And combining means for combining the two constant envelope signals output from the second selecting means and outputting the combined signal, wherein the first selecting means and the second selecting means include the transmission When the power is larger than a predetermined threshold, the path is switched to a path with higher gain, and when the transmission power is lower than the predetermined threshold, the path is switched to a path with lower gain.

  According to the present invention, when performing transmission power control in a LINC-type amplifier circuit that obtains a transmission signal by amplifying each of the two amplification means and then combining them, the gain is increased according to the transmission power of a desired magnitude. Two different routes are selected. As a result, transmission power control with a wide dynamic range can be performed, and amplification can always be performed with high power efficiency.

<< Summary of Invention >>
The amplifier circuit of the present invention performs transmission power control in a LINC-type amplifier circuit that generates two constant envelope signals from a transmission signal, individually amplifies each of the signals by two amplification means, and obtains the transmission signal. At this time, by selecting two paths having different gains according to a desired amount of transmission power, each of the first amplifier and the second amplifier is used in a range where the power efficiency is good. As a result, transmission power control with a wide dynamic range can be performed, and amplification can be performed with high 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, the same components are denoted by the same reference numerals, and redundant description is 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 shown in FIG. 1 includes a baseband unit 101, a constant envelope signal generation unit 102, variable attenuators 103a and 103b, first amplifiers 104a and 104b, first selection units 105a and 105b, and a second amplifier 106a. , 106b, lines 107a and 107b, second selection units 108a and 108b, a synthesis circuit 109, and a switch control unit and an attenuator control unit (not shown).

  The baseband unit 101 can be realized by a digital signal processing circuit such as ASIC or FPGA (Field Programmable Gate Array). The constant envelope signal generation unit 102 can be realized by a digital signal processing circuit such as an ASIC or FPGA, a D / A converter, and a quadrature modulator, for example. The variable attenuators 103a and 103b can be realized by, for example, a digital attenuator IC that determines an attenuation amount using a digital signal or an analog attenuator IC that determines an attenuation amount by voltage. The selection units 105a and 105b and the selection units 108a and 108b can be realized by, for example, an SPDT (single pole double throw) switch IC.

  The lines 107a and 107b can be realized by, for example, a microstrip line. The amplifiers 104a and 104b and the amplifiers 106a and 106b can be realized by, for example, FETs or transistors. The synthesizing circuit 109 can be realized by, for example, a Wilkinson type synthesizing circuit made of a microstrip line, a Silex synthesizing circuit, or a resistance synthesizing circuit.

  Next, the operation of the amplifier circuit 100 shown in FIG. 1 will be described. The constant envelope signal generation unit 102 generates two constant envelope signals S 1 and S 2 from the reception signal S input to the baseband unit 101. The two constant envelope signals S1 and S2 are attenuated to predetermined levels by the variable attenuators 103a and 103b, respectively, and then amplified by the first amplifiers 104a and 104b. When the amplified constant envelope signals S1 and S2 are output with a transmission power equal to or higher than a certain threshold value, the first selection units 105a and 105b and the second selection units 108a and 108b The path having the amplifiers 106a and 106b is selected and transmitted.

  That is, when the constant envelope signals S1 and S2 are output with transmission power equal to or higher than a certain threshold, the contacts of the first selection units 105a and 105b and the second selection units 108a and 108b are controlled by the control of the baseband unit 101. , Respectively, are selected for the paths of the second amplifiers 106a and 106b. Then, after the constant envelope signals S1 and S2 are respectively amplified by the second amplifiers 106a and 106b, the constant envelope signals S1 and S2 are synthesized by the synthesis circuit 109, and the final amplified signal S is output.

  At this time, a certain threshold value for determining the transmission power level is determined from the power efficiency with respect to the output power of the second amplifiers 106a and 106b, for example, the minimum output power as a range that can be used with a power efficiency of 50% or more. The threshold is used. Alternatively, when a class D amplifier or a class F amplifier is used as the second amplifiers 106a and 106b, by setting the operating point of the amplifier as a threshold value, a range of output levels with high power efficiency in the second amplifiers 106a and 106b. To use.

  When the constant envelope signals S1 and S2 are output with a transmission power equal to or lower than a certain threshold, the baseband unit 101 controls the first selection circuits 105a and 105b and the second selection circuits 108a and 108b to perform an amplifier. The routes of the lines 107a and 107b that do not have a line are selected. Then, after the constant envelope signals S1 and S2 pass through the respective lines 107a and 107b, the synthesis circuit 109 synthesizes the constant envelope signal S1 and the constant envelope signal S2 and outputs an amplified signal S.

  At that time, the power supplies of the second amplifiers 106a and 106b that are not used are turned off. At this time, since the first amplifiers 104a and 104b output a large amount of power by the gain of the second amplifiers 106a and 106b, they are used within a range of power efficient output levels.

  Even if the transmission power is greater than or less than the threshold, the attenuators 103a and 103b are controlled by the baseband unit 101 according to the desired transmission power when performing finer transmission power control. The transmission power is controlled by attenuating the amplitudes of the two constant envelope signals S1, S2. In this way, the transmission power control is performed, and when the transmission power is equal to or greater than the threshold, the constant envelope signals S1 and S2 are synthesized after being amplified by the second amplifiers 106a and 106b, and when the transmission power is equal to or less than the threshold, By combining the constant envelope signals S1 and S2 after being amplified by one amplifier 104a and 104b, it is possible to perform transmission power control in a wide dynamic range and use an amplifier circuit at an output level with good power efficiency.

  As described above, according to the amplifier circuit according to the first embodiment of the present invention, the two constant envelope signals S1 and S2 are amplified by the first amplifiers 104a and 104b, and then transmitted with a desired magnitude. It is determined whether to pass through the second amplifiers 106a and 106b according to the power. That is, when a certain transmission power is exceeded, the path having the second amplifiers 106a and 106b is selected by the first selection circuits 105a and 105b and the second selection circuits 108a and 108b. When the transmission power is less than or equal to a certain transmission power, a path that does not have the second amplifiers 106a and 106b is selected, and the power of the second amplifiers 106a and 106b is turned off. As a result, the first amplifiers 104a and 104b and the second amplifiers 106a and 106b can be used in a power efficient range. Therefore, even in the case of small transmission power, it is possible to efficiently amplify and widen the dynamic range of the amplifier circuit.

  In the above description, the transmission power is controlled using the path having the second amplifiers 106a and 106b and the path not having the second amplifiers 106a and 106b. However, the present invention is not limited to this. Even when switching is performed using two paths having different amplifiers, and the power of the amplifiers on the unused paths is turned off, the same effect as described above can be obtained.

<< Embodiment 2 >>
FIG. 2 is a block diagram showing a configuration of the amplifier circuit according to the second embodiment of the present invention. The difference between the amplifier circuit 100a of the second embodiment shown in FIG. 2 and the amplifier circuit 100 of the first embodiment shown in FIG. 1 is that the adjustment lines 110a and 110b, which are electric length adjustment lines, and the susceptances 111a and 111b, 1 are added to the circuit lines 112a and 112b for the synthesis circuit, and the synthesis circuit 109 in FIG. 1 is deleted. Note that the synthetic circuit lines 112a and 112b in FIG. 2 correspond to the synthetic circuit 109 of the first embodiment shown in FIG.

  The adjustment lines 110a and 110b can be realized by a microstrip line or the like. The susceptances 111a and 111b can be realized by an inductor, a capacitor, a microstrip line, or the like. The synthetic circuit lines 112a and 112b can be realized by, for example, a microstrip line.

  Next, the operation of the amplifier circuit 100a according to the second embodiment shown in FIG. 2 will be described while avoiding redundant description of the parts described in the amplifier circuit 100 according to the first embodiment. The combined circuit lines 112a and 112b have an electrical length of λ / 4 with respect to the signal frequency λ, and the electrical length between the amplifiers 106a and 106b is λ / 2. It has become. When the transmission power control is performed by the amplifier circuit 100a and the first selection circuits 105a and 105b and the second selection circuits 108a and 108b select the second amplifiers 106a and 106b, the second amplifiers 106a and 106b The adjustment line 110a so that the electrical length L of the lines 110a and 110b from the output to the synthesis circuit lines 112a and 112b and the selection circuits 108a and 108b is n × λ / 2 (n is an integer of 0 or more). 110b is designed. As a result, the electrical length L between the second amplifiers 106a and 106b becomes n × λ + λ / 2, and the combined circuit lines 112a and 112b, which are combined circuits, perform an optimum operation.

  When the second amplifiers 106a and 106b are not selected, the final stage amplifiers before the synthesis circuit lines 112a and 112b are the first amplifiers 104a and 104b. At that time, the electrical length L of each path of the first selection circuits 105a and 105b, the lines 107a and 107b, and the second selection circuits 108a and 108b becomes n × λ / 2 (n is an integer of 0 or more). Thus, the lines 107a and 107b are adjusted in advance. As a result, even when a path that does not have the second amplifiers 106a and 106b is selected, the electrical length L between the amplifiers at the final stage becomes n × λ + λ / 2, and the combined circuit lines 112a and 112b that are combined circuits. Performs optimal operation.

  As described above, according to the amplifier circuit 100a of the second embodiment of the present invention as shown in FIG. 2, the two paths having different gains (that is, the paths of the second amplifiers 106a and 106b and the lines 107a and 107b). Regardless of which path is selected, the line is adjusted so that the electrical length L between the amplifiers at the final stage becomes n × λ + λ / 2, and the combined circuit (that is, the combined circuit lines 112a and 112b) Can be operated optimally. Therefore, since distortion does not occur in the output signal S when the two constant envelope signals S1 and S2 are combined, transmission power control can be performed with high power efficiency while maintaining good linearity even when the path is switched.

<< Embodiment 3 >>
FIG. 3 is a block diagram showing the configuration of the amplifier circuit according to Embodiment 3 of the present invention. The amplifier circuit 100b of the third embodiment shown in FIG. 3 is different from the amplifier circuit 100a of the second embodiment shown in FIG. 2 in that the paths of the lines 107a and 107b in FIG. 106d and the lines 110c and 110d.

  That is, in the amplifier circuit configured to switch using two paths having amplifiers having different gains, the switching between the path of the second amplifiers 106a and 106b and the path of the lines 107a and 107b as shown in FIG. 2 is not performed. As shown in FIG. 3, adjustment lines 110a to 110d are provided at the output ends of the second amplifiers 106a and 106b and the third amplifiers 106c and 106d, respectively, and the electrical lengths of the adjustment lines 110a to 110d and the selection circuits 108a and 108b are provided. By adjusting the adjustment lines 110a to 110d so that L is n × λ / 2 (n is an integer equal to or larger than 0), the synthesis circuit (that is, for the synthesis circuit) can be obtained as in the second embodiment of FIG. The lines 112a and 112b) can be optimally operated.

  In each of the amplifier circuit 100a in FIG. 2 and the amplifier circuit 100b in FIG. 3, the electrical length L of the passage path of each of the first selection circuits 105a and 105b and the second selection circuits 108a and 108b is the wavelength of the signal. When it is sufficiently short with respect to λ, the electrical length L of these selection circuits (that is, the first selection circuits 105a and 105b and the second selection circuits 108a and 108b) can be ignored. Therefore, the synthesis circuit (that is, the synthesis circuit lines 112a and 112b) can be optimally operated without using the lines 110a to 110d as shown in FIG. Further, by setting the electrical length L of the lines 107a and 107b as shown in FIG. 2 to n × λ / 2, the combined circuit (that is, the combined circuit lines 112a and 112b) can be optimally operated.

<< Embodiment 4 >>
FIG. 4 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 4 of the present invention. The difference between the amplifier circuit 100c of the fourth embodiment shown in FIG. 4 and the amplifier circuit 100 of the first embodiment shown in FIG. 1 is that the amplifier circuit 100c of FIG. 4 and the variable attenuators 103a and 103b of FIG. This is the point where the control unit is removed. Therefore, in the amplifier circuit 100c of the fourth embodiment shown in FIG. 4, the bias of the first amplifiers 104a and 104b and the second amplifiers 106a and 106b can be controlled directly from the baseband unit 101.

  Next, the operation of the amplifier circuit 100c of the fourth embodiment shown in FIG. 4 will be described avoiding duplication. In the case of outputting a transmission power that exceeds a certain threshold, the first amplifier circuits 105a and 105b and the second selector circuits 108a and 108b select the path to be amplified by the second amplifiers 106a and 106b. When the transmission power is further controlled within a range equal to or greater than this threshold, the bias power supply of the second amplifiers 106a and 106b is controlled from the baseband unit 101 according to a desired transmission power value.

  When outputting transmission power below a certain threshold, the first selection circuits 105a and 105b and the second selection circuits 108a and 108b select the paths of the lines 107a and 107b having no amplifier. When the transmission power is further controlled within the range below this threshold, the bias power of the first amplifiers 104a and 104b is controlled from the baseband unit 101 according to a desired transmission power value, thereby controlling the transmission power. By controlling the bias power supply of the first amplifiers 104a and 104b in this way, the transmission power can be controlled without reducing the power efficiency. As described above, according to the amplifier circuit of the fourth embodiment of the present invention, even when the transmission power is finely controlled with a wide dynamic range, the transmission power control can be performed with the power efficiency of the amplifier circuit being high. it can.

<< Embodiment 5 >>
In the fifth embodiment, a wireless device such as a wireless transmission / reception device using the amplifier circuit of each of the above inventions is described. FIG. 5 is a block diagram showing a configuration of a radio apparatus according to Embodiment 5 of the present invention. In FIG. 5, the amplifier circuit 100 is the amplifier circuit according to the first embodiment described above, and thus the description of its operation is omitted.

  In FIG. 5, the wireless transmission / reception apparatus 200 includes an amplification circuit 100, an antenna 201, an antenna duplexer 202, a wireless reception circuit 203, and a modem unit 204. The antenna 201 is an antenna that transmits or receives a radio signal. The antenna duplexer 202 is an antenna sharing unit that shares one antenna for transmission and reception, and outputs a signal output from the amplifier circuit 100 to the antenna 201 and captures a signal received by the antenna 201 into the wireless reception circuit 203. It has.

  The wireless reception circuit 203 is a circuit that extracts a desired reception signal from the signal output from the antenna duplexer 202. For example, a low noise amplifier, a mixer that performs frequency conversion, a filter, a variable gain amplifier, an A / D converter, or the like It consists of The modem unit 204 has a function of modulating a signal such as voice, video, and data into a signal for wireless transmission, and demodulating a signal received wirelessly into a signal such as voice, video, and data. The amplifier circuit 100 is an amplifier circuit that amplifies the signal shown in the first embodiment.

  The wireless transmission / reception apparatus 200 according to the fifth embodiment is configured to use the amplification circuit 100 shown in the first embodiment for amplification of transmission, performs transmission power control in a wide dynamic range, and performs power efficient amplification. it can. As described above, according to the fifth embodiment, amplification can be performed with high power efficiency while performing transmission power control in a wide dynamic range in the LINC-type amplifier circuit 100 mounted on the wireless transmission / reception apparatus 200. Further, the radio transmission / reception device described in Embodiment 5 can also be applied to a base station device, a communication terminal device, and the like.

<< Embodiment 6 >>
FIG. 6 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 6 of the present invention. The difference between the amplifier circuit 100d of the sixth embodiment shown in FIG. 6 and the amplifier circuit 100c of the fourth embodiment shown in FIG. 4 is that the amplifier circuit 100d of FIG. 6 calculates the amplitude value for calculating the amplitude value in the original signal. Unit 113, memory 114 that stores phase control values of two constant envelope signals according to the amplitude value, variable phase unit 115a that controls the phase of the two constant envelope signals according to the value to be controlled, and 115b. Therefore, in the amplifier circuit 100d of the sixth embodiment shown in FIG. 6, phase control necessary for distortion compensation can be performed according to the amplitude value of the original signal. The memory 114 has a function of changing the stored phase control value according to the transmission power control value input from the baseband unit 101.

  The variable phase sections 115a and 115b can be realized by changing the phases of the two constant envelope signals by an analog variable phase shifter or digital signal processing.

  Next, the operation of the amplifier circuit 100d according to the sixth embodiment shown in FIG. 6 will be described while avoiding duplication. The amplitude calculation unit 113 calculates the amplitude value of the modulation signal S output from the baseband unit 101. The calculated amplitude value is sent to the memory 114, and the stored phase control value is read out according to the amplitude value, and sent to the variable phase units 115a and 115b. The phase control value stored in the memory 114 will be described with reference to FIG. FIG. 7 shows output levels when Sin waves are input as two constant envelope signals and the phase difference between the two constant envelope signals is changed. For example, when the bias power supply of the second amplifiers 106a and 106b is set to V1, the output level drops below the ideal output level as shown in FIG. This is a phenomenon that occurs when the second amplifiers 106a and 106b are connected by the line 112a and the line 112b constituting the combiner and there is no isolation. Since the output level is reduced, when the modulation signal is output, the modulation signal is distorted. Therefore, in order to compensate the amplified signal S so as not to be distorted in the second amplifiers 106a and 106b, the ideal output is obtained on the output line when the power supply bias is V1, as shown in FIG. A phase control value for performing control so as to narrow the phases of the two constant envelope signals is stored as a table in the memory 114 so as to obtain the phase value.

  Further, as described in the fourth embodiment, in the amplifier 100d, when the transmission power exceeding a certain threshold is output, the path amplified by the second amplifiers 106a and 106b is defined as the first selection circuit 105a. , 105b and the second selection circuits 108a and 108b, and when the transmission power is further controlled within a range equal to or greater than the threshold, the second amplifier 106a is selected from the baseband unit 101 according to a desired transmission power value. , 106b is controlled. For example, when the bias power supply is changed from V1 to V2, the degree of decrease from the ideal output level with respect to the phase difference may be different as shown in FIG. In this case, since the phase control value necessary for obtaining the inverse distortion characteristic for compensating for the distortion changes, a table corresponding to each phase control value is stored in the memory 114 and the base control value is stored. The bias control information is sent from the band unit 101 to the memory 114, and the table is switched according to the value. As a result, the output signal has no distortion, and deterioration of communication quality can be suppressed. Similarly, when the lines 107a and 107b are selected, the phase control value for compensating for distortion may change. Also in this case, it is possible to compensate for distortion by holding a separate table in the memory 114 and selecting the table according to transmission power control. The baseband unit 101 functions as distortion compensation means.

  As described above, according to the amplifier circuit 100d of the sixth embodiment of the present invention, even when distortion occurs in the second amplifiers 106a and 106b, it corresponds to each case where transmission power is finely controlled with a wide dynamic range. By holding the table in the memory 114, the signal can be amplified with high efficiency and good linearity.

  In the sixth embodiment, the case where only the phase control is performed in order to give the inverse distortion characteristic has been described. However, in the phase control units 115a and 115b, only the amplitude control, not the phase, or the phase and amplitude are controlled. The same effect can be obtained even if both are controlled to give reverse distortion characteristics. In the sixth embodiment, the configuration for controlling both phases of two constant envelope signals has been described, but the same effect can be obtained by controlling either one of the constant envelope signals.

  Also, as shown in FIG. 8, an amplitude correction unit 116 is provided after the baseband unit 101 except for the phase control units 115a and 115b that perform phase control of two constant envelope signals in FIG. A similar effect can be obtained by controlling the amplitude of the original signal S in accordance with the amplitude control value for giving the reverse distortion characteristic.

  In FIG. 8, only the amplitude control is performed to give the reverse distortion characteristic. However, depending on the distortion, only the phase control or both the phase and amplitude are controlled to give the reverse distortion characteristic. An effect is obtained.

  In the second to sixth embodiments, the electrical length between the amplifiers is designed to be an integral multiple of λ / 2, but the effect can be obtained even if there is a deviation of about 15%. I can do it.

<< Embodiment 7 >>
FIG. 9 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 7 of the present invention. The amplifier circuit 100f of the seventh embodiment shown in FIG. 9 is different from the amplifier circuit 100d of the sixth embodiment shown in FIG. 6 in the amplifier circuit 100d of FIG. 9 and between the line 107a and the selector 108a. 107b and the selector 108b are connected by a resistor 117, and a part of the lines 107a and 107b and the selectors 108a and 108b are combined circuits corresponding to the combined circuit 109 of the first embodiment shown in FIG. When 109 is configured, the resistor 117 operates as a Wilkinson combiner.

  Next, the operation of the amplifier circuit 100f of the seventh embodiment shown in FIG. 9 will be described avoiding duplication. In this amplifier circuit 100f, when outputting transmission power below a certain threshold value, a path passing through the lines 107a and 107b is selected by the first selection circuits 105a and 105b and the second selection circuits 108a and 108b. When the transmission power is further controlled within the range below this threshold, the baseband unit 101 controls the bias power supplies of the first amplifiers 104a and 104b in accordance with the desired transmission power value. At this time, the resistor 117, the selectors 108 a and 108 b, the combiner 109, and the resistor 117 connected in the middle of the line 107 a and the line 107 b or in the subsequent stage operate as a Wilkinson combiner. This can be realized by setting the electrical length from the stage after the point where the resistor 117 is connected to the output end to an integer multiple of λ / 4 with respect to the wavelength of the carrier frequency. When the signal is synthesized by the Wilkinson synthesizer, the second amplifiers 106a and 106b are isolated from each other, so that the signal level is not lowered as shown in FIG. This eliminates the need for the table in the memory 114 when the transmission power is below a certain threshold value, thereby reducing the amount of memory.

  As described above, according to the amplifier circuit 100f of the seventh embodiment of the present invention, when the transmission power is below a certain threshold, the synthesis circuit 109 operates as a Wilkinson synthesizer, so that distortion does not occur and compensation is performed. The amount of memory required can be reduced.

  Note that a wireless device such as the wireless transmission / reception device illustrated in FIG. 5 of the fifth embodiment can be configured using the amplifier circuit 100d in the sixth embodiment and the amplifier circuit 100f in the seventh embodiment. In this case, in FIG. 5 which is a block diagram of the wireless device, the amplifier circuit 100 can be the amplifier circuit 100d of the sixth embodiment and the amplifier circuit 100f of the seventh embodiment.

  With the configuration of the wireless device as described above, the same operation as that of the wireless transmission / reception device 200 of the fifth embodiment is performed, and the transmission power control with a wide dynamic range is performed in the LINC amplifier circuit 100 mounted on the wireless transmission / reception device 200. Amplification can be performed with high power efficiency. In addition, the linearity of the amplification is good, and deterioration of communication quality can be suppressed. Further, the wireless transmission / reception apparatus as described above can be applied to a base station apparatus, a communication terminal apparatus, and the like.

  As described above, the amplifier circuit of the present invention can perform transmission power control in a wide dynamic range and perform amplification with high power efficiency and good linearity, so that a radio transmission / reception device, a base station device, and a communication terminal device can be used. It can be used effectively.

1 is a block diagram showing a configuration of an amplifier circuit according to Embodiment 1 of the present invention. The block diagram which shows the structure of the amplifier circuit in Embodiment 2 of this invention The block diagram which shows the structure of the amplifier circuit in Embodiment 3 of this invention The block diagram which shows the structure of the amplifier circuit in Embodiment 4 of this invention FIG. 9 is a block diagram showing a configuration of a radio apparatus according to Embodiment 5 of the present invention. The block diagram which shows the structure of the amplifier circuit in Embodiment 6 of this invention. The graph which shows the output level with respect to the phase difference of two constant envelope signals The block diagram which shows the structure of the other amplifier circuit in Embodiment 6 of this invention. The block diagram which shows the structure of the amplifier circuit in Embodiment 7 of this invention Block diagram showing the configuration of a conventional LINC amplifier circuit The figure which shows the signal of the amplifier circuit by the conventional LINC system shown in FIG. 10 by the vector of an orthogonal plane coordinate Block diagram showing the configuration of a conventional transmission circuit that performs transmission power control

Explanation of symbols

100, 100a, 100b, 100c, 100d, 100e, 100f Amplifier circuit 101 Baseband unit 102 Constant envelope signal generation unit 103a, 103b Variable attenuator 104a, 104b First amplifier 105a, 105b First selection circuit 106a, 106b First Second amplifier 106c, 106d Third amplifier 107a, 107b Line 108a, 108b Second selection circuit 109 Synthesis circuit 110a, 110b, 110c, 110d Adjustment line 111a, 111b Susceptance 112a, 112b Line for synthesis circuit 113 Amplitude calculation section 114 Memory 115a, 115b Variable phase unit 116 Amplitude correction unit 117 Resistance 200 Radio transmission / reception device 201 Antenna 202 Antenna duplexer 203 Radio reception circuit 204 Modulation / demodulation unit

Claims (7)

Constant envelope signal generation means for generating two constant envelope signals from the input signal;
First amplification means for individually amplifying the two constant envelope signals,
First and second selection means for selectively switching the output paths of the first amplification means to two paths having different gains;
Second amplification means present in at least one of the two paths;
Combining means for combining the two constant envelope signals output from the second selection means and outputting the combined signal;
The first selection unit and the second selection unit switch to a path with a large gain when the transmission power is larger than a predetermined threshold, and switch to a path with a small gain when the transmission power is smaller than a predetermined threshold. An amplifier circuit characterized by that.   The electrical length L of the path from the output terminal of the final stage amplifier preceding the combining means to the output terminal of the combining circuit is L = {(n × λ) with respect to the wavelength λ of the frequency of the two constant envelope signals. The amplification circuit according to claim 1, wherein: (2) + (λ / 4)} (where n is 0 or a natural number).   3. The amplifier circuit according to claim 1, wherein a bias power source of the first amplifying unit and the second amplifying unit is controlled according to the control of the transmission power.   When the two constant envelope signals are not amplified by the first amplifying means and the second amplifying means, a control is performed so as not to apply bias power to the first amplifying means and the second amplifying means. The amplifier circuit according to claim 3. Amplitude calculating means for calculating an amplitude value of the input signal;
Storage means for storing at least one of a phase control value or an amplitude control value of two constant envelope signals according to the amplitude value calculated by the amplitude calculation means;
Distortion compensation means for controlling at least one of amplitude or phase in at least one of the input signal or the two constant envelope signals;
When the transmission power control is performed, the distortion compensation unit switches at least one of the phase control value or the amplitude control value for distortion compensation stored in the storage unit according to the transmission power control. The amplifier circuit according to any one of claims 2 to 4.   When a resistance is provided between one of the paths selected by the first selection means and the second selection means, and the path having the resistance is selected, the selected path and the subsequent stage are selected. 6. An amplifier circuit according to claim 5, wherein the means, the synthesis circuit and the resistor operate as a Wilkinson synthesizer.   A wireless device comprising the amplifier circuit according to claim 1.

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