JP2005269346A - Polar modulation transmitter and polar modulation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polar modulation transmitter which has excellent power efficiency and a wide control range of transmission output power and can form a transmission signal with high quality. <P>SOLUTION: The polar modulation transmitter is provided with an amplitude modulation switching mode for continuously changing distributions Pin and Vccin of total output power Pout to a variable gain amplifying part and a high frequency power amplifier when one mode is changed to the other mode in addition to a high frequency power amplifier amplitude modulation mode and a variable gain amplifying part amplitude modulation mode. Thus, the transient response when mode switching is suppressed, thereby obtaining a satisfactory transmission output signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention particularly relates to a transmission apparatus using a polar modulation scheme.

  Conventionally, class A or class AB linear amplifiers have been used for high frequency power amplifiers that amplify modulated signals including envelope fluctuation components in order to linearly amplify envelope fluctuation components. Such a linear amplifier is excellent in linearity, but consumes electric power associated with a DC bias component at all times, and therefore has lower power efficiency than a non-linear amplifier of class C or class E. For this reason, when such a high-frequency power amplifier is applied to a portable radio device using a battery as a power source, there is a situation in which the use time is shortened because the power consumption of the high-frequency power amplifier is large. In addition, when applied to a base station apparatus of a wireless system in which a plurality of high-power transmission apparatuses are installed, there are circumstances in which the apparatus becomes large and the amount of heat generation increases.

  Therefore, a transmission apparatus using a polar modulation method, which has been proposed as a highly efficient transmission apparatus, has been proposed. As shown in FIG. 19, the polar modulation transmission apparatus includes an amplitude phase separation unit 10, an amplitude modulation signal amplifier 11, a frequency synthesizer 12 used as a phase modulation unit, and a high frequency power amplifier 13 that is a nonlinear amplifier. .

  The amplitude phase separation unit 10 receives the baseband modulation signal S1, and separates it into a baseband amplitude modulation signal (hereinafter referred to as an amplitude modulation signal) S2 and a baseband phase modulation signal S3. The baseband amplitude modulation signal S2 is supplied to the non-linear high frequency power amplifier 13 as a power supply voltage of the high frequency power amplifier 13 through the amplitude modulation signal amplifier 11. The baseband phase modulation signal S3 is input to the frequency synthesizer 12. The frequency synthesizer 12 obtains a high-frequency phase modulation signal S4 by phase-modulating the carrier signal with the baseband phase modulation signal S3, and sends this to the high-frequency power amplifier 13. Thereby, the high frequency power amplifier 13 amplifies the baseband phase modulation signal S3 based on the power supply voltage corresponding to the baseband amplitude modulation signal S2, and outputs this as the transmission output signal S5.

  Next, the operation of the polar modulation transmission apparatus will be described. First, if the baseband modulation signal S1 is Si (t), Si (t) can be expressed by the following equation.

Si (t) = a (t) exp [jφ (t)] (1)
Here, a (t) represents amplitude data, and exp [jφ (t)] represents phase data.

  The amplitude phase separator 10 extracts amplitude data a (t) and phase data exp [jφ (t)] from Si (t). Here, the amplitude data a (t) corresponds to the amplitude modulation signal S2, and the phase data exp [jφ (t)] corresponds to the baseband phase modulation signal S3. The amplitude data a (t) is amplified by the amplitude modulation signal amplifier 11 and supplied to the high frequency power amplifier 13. Thereby, the power supply voltage value of the high frequency power amplifier 13 is set based on the amplitude data a (t).

  The frequency synthesizer 12 generates a high frequency phase modulation signal S4 obtained by modulating the carrier angular frequency ωc with the phase data exp [jφ (t)], and this is input to the high frequency power amplifier 13. Here, when the high-frequency phase modulation signal S4 is Sc, Sc can be expressed by the following equation.

Sc = expj [ωct + φ (t)] (2)
By using a non-linear amplifier as the high-frequency power amplifier 13, a signal obtained by multiplying the power supply voltage value a (t) of the high-frequency power amplifier 13 and the output signal of the frequency synthesizer 12 is amplified by the gain G of the high-frequency power amplifier 13. The transmission output signal S5 thus obtained is obtained. Here, when the transmission output signal S5 is an RF signal Srf, the RF signal Srf can be expressed by the following equation.

Srf = Ga (t) Sc = Ga (t) expj [ωct + φ (t)] (3)
Since the signal input to the high frequency power amplifier 13 is a phase modulation signal having no fluctuation component in the amplitude direction, it becomes a constant envelope signal. Therefore, since a highly efficient nonlinear amplifier can be used as the high frequency power amplifier 13, a highly efficient transmission device can be provided. A technique using this type of polar modulation is described in Patent Document 1 and Patent Document 2, for example.
Japanese Patent No. 3207153 JP 2001-156554 A

  However, in the conventional polar modulation transmission apparatus, when the output power of the high-frequency power amplifier 13 is controlled, the output signal does not change linearly with respect to the input signal because the high-frequency power amplifier 13 is a non-linear amplifier. Therefore, the average signal level control using the transmission power control signal (hereinafter referred to as the gain control signal) also needs to be performed by changing the power supply voltage in the same manner as the instantaneous amplitude control using the baseband amplitude modulation signal. In this case, the control range of the output power is limited by the operation limit of the transistor with respect to the leakage power or the power supply voltage.

  The present invention has been made in view of this point, and an object of the present invention is to provide a polar modulation transmission apparatus having good power efficiency and a wide control range of transmission output power. It is another object of the present invention to provide a polar modulation transmission apparatus and a polar modulation method capable of forming a transmission signal with good quality.

  In order to solve such a problem, a polar modulation transmission apparatus according to the present invention includes a high frequency power amplifier that changes the amplitude of a high frequency phase modulation signal in accordance with an amplitude modulation signal, and a variable gain amplification unit provided on the front side of the high frequency power amplifier. A first mode in which an amplitude modulation signal is assigned to a high frequency power amplifier, a second mode in which an amplitude modulation signal is assigned to a variable gain amplifier, and an amplitude modulation signal is allocated to both the high frequency power amplifier and the variable gain amplifier. An amplitude control unit that controls whether to apply an amplitude variation to the high-frequency phase modulation signal based on the amplitude modulation signal by the high-frequency power amplifier and / or the variable gain amplification unit. The structure which comprises is taken.

  According to this configuration, in the first mode (for example, when high-level transmission output power is obtained), the high-frequency power amplifier is operated as a non-linear amplifier, and the high-frequency power amplifier performs high-frequency phase modulation according to the amplitude modulation signal. By changing the amplitude of the signal, power efficiency can be significantly increased. In the second mode (for example, when low-level transmission output power is obtained), the high-frequency power amplifier is operated as a linear amplifier, and the high-frequency phase based on the amplitude-modulated signal (and further the gain control signal) is operated by the variable gain amplifier. Controls the amplitude of the modulation signal. As a result, it is possible to apply amplitude fluctuations over a wide level to the high-frequency phase modulation signal while maintaining high power efficiency by the high-frequency power amplifier.

  In addition, since there is a third mode in which the amplitude modulation signal is allocated and allocated to both the high frequency power amplifier and the variable gain amplification unit, the subtle amplitude fluctuations corresponding to the amplitude modulation signal are further increased with respect to the high frequency phase modulation signal. In addition, it is possible to suppress the transient response that occurs when the mode is switched between the first mode and the second mode, and it is possible to form a transmission signal with good quality.

  In the polar modulation transmission apparatus of the present invention, the amplitude control unit is configured to switch the third mode when switching the mode from the first mode to the second mode, or when switching the mode from the second mode to the first mode. A configuration is adopted in which the mode is switched through the mode.

  According to this configuration, when the mode is switched between the first mode and the second mode, the high-frequency power amplifier and the variable gain amplifying unit are not suddenly switched from one mode to the other mode. Since the state is continuously and gently switched through the mode 3, the transient response at the time of mode switching is suppressed, and the deterioration of the quality of the transmission output signal that occurs at the time of mode switching is suppressed.

  In the polar modulation transmission apparatus of the present invention, the amplitude control unit uses the input amplitude modulation signal and the first, second, and third modes as addresses, and uses the input amplitude modulation signal as a high-frequency power amplifier and a variable gain amplification unit. And a transient state control table in which the values allocated to each address are stored in association with each address.

  According to this configuration, the input amplitude-modulated signal can be easily distributed to the high-frequency power amplifier and the variable gain amplifier according to each mode.

  The polar modulation method of the present invention includes a high frequency power amplifier amplitude modulation step for changing the amplitude of a high frequency phase modulation signal according to the amplitude modulation signal using a high frequency power amplifier, and an amplitude of the high frequency phase modulation signal using a variable gain amplification unit. Variable gain amplification unit amplitude modulation step for changing the amplitude modulation signal according to the amplitude modulation signal, and distributing the amplitude modulation signal to both the high frequency amplifier and the variable gain amplification unit, and using both the high frequency power amplifier and the variable gain amplification unit An amplitude modulation switching step of changing the amplitude of the phase modulation signal in accordance with the amplitude modulation signal.

  According to this method, since the high frequency power amplifier amplitude modulation step and the variable gain amplification unit amplitude modulation step are performed, the high frequency power amplifier is provided with a high level of amplitude variation over a wide level while maintaining high power efficiency. Can do. In addition, since it has an amplitude modulation switching step, at the time of switching from the high frequency power amplifier amplitude modulation step to the variable gain amplification unit amplitude modulation step, or at the time of switching from the variable gain amplification unit amplitude modulation step to the high frequency power amplifier amplitude modulation step The transient response can be suppressed, and as a result, a high-quality transmission signal can be formed.

  Thus, according to the present invention, since the power efficiency is good and the control range of the transmission output power is wide, the transient response at the time of mode switching can be suppressed, so that a transmission signal with high quality can be formed. A polar modulation transmission apparatus and a polar modulation method can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a schematic configuration of a polar modulation transmission apparatus according to Embodiment 1 of the present invention. The polar modulation transmission device 100 is configured to transmit the baseband modulation signal S1 using a polar modulation method.

  Polar modulation transmission apparatus 100 inputs baseband modulation signal S1 to amplitude phase separation section 101. The amplitude phase separation unit 101 separates the baseband modulation signal S1 into a baseband amplitude modulation signal S2 and a baseband phase modulation signal S3.

  The baseband amplitude modulation signal S <b> 2 is input to the multiplier 102 of the amplitude control unit 120. Multiplier 102 multiplies baseband amplitude modulation signal S 2 and gain control signal S 12, and sends the multiplication result to terminal a of switch 103. Further, a DC voltage value S11 is given to the terminal b of the switch 103, and the switch 103 responds to the mode switching signal S10, and the amplitude modulation signal continues with the baseband amplitude modulation signal S2 or the DC voltage value S11 multiplied by the gain. Output to the amplifier 104. The amplitude modulation signal amplifier 104 generates a power supply voltage for the high-frequency power amplifier 105 from the signal input from the switch 103 and supplies it to the high-frequency power amplifier 105. Here, the amplitude modulation signal amplifier 104 is preferably a class D amplifier that represents amplitude information with a pulse width in order to change the power supply voltage with high efficiency in accordance with the level of the baseband amplitude modulation signal S2.

  Thus, in polar modulation transmission apparatus 100, whether high-frequency power amplifier 105 is supplied with a power supply voltage based on gain-controlled baseband modulation signal S2 or a fixed power supply voltage based on DC voltage value S11 is determined. Thus, the selection can be made according to the mode switching signal S10. That is, according to the mode switching signal S10, it is possible to select whether the high-frequency power amplifier 105 is operated nonlinearly or linearly. That is, the switch 103 functions as a power supply voltage supply unit that selectively supplies the high-frequency power amplifier 105 with a power supply voltage corresponding to the baseband amplitude modulation signal S2 or a predetermined fixed power supply voltage.

  On the other hand, the baseband phase modulation signal S3 is first input to a frequency synthesizer 106 used as a phase modulation unit. The frequency synthesizer 106 obtains a high-frequency phase modulation signal S4 by phase-modulating the carrier frequency with the baseband phase modulation signal S3, and sends this to the variable gain amplification unit 107.

  In the case of this embodiment, the variable gain amplification unit 107 includes a variable gain amplifier 108 and a multiplier 109. First, the high frequency phase modulation signal S4 is input to the variable gain amplifier 108. The variable gain amplifier 108 receives the gain control signal S21 offset by the gain offset signal S20 by the adder 110. Incidentally, the gain offset signal S20 is set so that the variable gain amplifier 108 can obtain a signal having a level suitable for operating the high-frequency power amplifier 105 as a non-linear amplifier in a saturation operation or switching operation region. The variable gain amplifier 108 amplifies the high-frequency phase modulation signal S4 according to the gain control signal S21, and sends the amplified signal to the multiplier 109.

  The multiplier 109 receives either the baseband amplitude modulation signal S2 or the baseband amplitude modulation signal S2 whose lower limit value is limited by the lower limit value limiting circuit 112 via the switch 111. The lower limit limiting circuit 112 limits the lower limit of the amplitude fluctuation of the baseband amplitude modulation signal S2. As a result, the multiplier 109 multiplies either the baseband amplitude modulation signal S2 with the lower limit restricted or the baseband amplitude modulation signal S2 with no lower limit restricted by the high-frequency phase modulation signal S4 after gain control, and the multiplication result. Is sent to the high-frequency power amplifier 105.

  The high frequency power amplifier 105 amplifies the high frequency phase modulation signal input from the variable gain amplification unit 107 using the power supply voltage value supplied from the amplitude modulation signal amplifier 104, thereby obtaining a transmission output signal S30.

  Next, the operation of the polar modulation transmission apparatus 100 will be described. In FIG. 1, the operation mode of the high-frequency power amplifier 105 depends on, for example, the transmission power level designation from the radio base station to the polar modulation transmission apparatus 100 or the transmission power level based on the state of the received signal of the polar modulation transmission apparatus 100. It is determined.

  When increasing the level of the transmission output signal S30, an operation mode in which the high-frequency power amplifier 105 is a nonlinear amplifier is desirable from the viewpoint of power efficiency. On the other hand, when the level of the transmission output signal S30 becomes low and the high frequency power amplifier 105 is out of the range where it can operate as a nonlinear amplifier, it is desirable to operate the high frequency power amplifier 105 as a linear amplifier.

  Paying attention to this point, the polar modulation transmitter 100 prepares the mode switching signal S10 and switches the operation mode of the high-frequency power amplifier 105 between a mode in which it operates as a nonlinear amplifier and a mode in which it operates as a linear amplifier. Mode switching signal S10 is set based on a desired transmission power level and characteristics of high-frequency power amplifier 105.

  Note that the mode switching signal S10, the DC voltage value S11, the gain control signal S12, and the gain offset signal S20 input to the polar modulation transmission apparatus 100 are set by, for example, a control unit (not shown).

  Connection of the switches 103 and 111 in FIG. 1 indicates a case where the level of the transmission output signal S30 is relatively high. First, the case where the level of the transmission output signal S30 is relatively high will be described. In this case, the high frequency power amplifier 105 operates as a nonlinear amplifier in a saturation operation or switching operation region. In this case, the high frequency power amplifier 105 performs amplitude modulation of the high frequency phase modulation signal. Specifically, when the terminal a and the terminal c of the switch 103 are connected by the mode switching signal S10, the multiplication value of the baseband amplitude modulation signal S2 and the gain control signal S12 output from the terminal c of the switch 103 is After being amplified by the amplitude modulation signal amplifier 104, it is applied to the high frequency power amplifier 105 as a power supply voltage of the high frequency power amplifier 105. As a result, the high frequency power amplifier 105 performs amplitude modulation operation.

  On the other hand, for the high-frequency phase modulation signal S4, when the level of the transmission output signal S30 is relatively high, the terminal a and the terminal c of the switch 111 are connected by the mode switching signal S10. As a result, a signal in which the lower limit value of the amplitude fluctuation of the baseband amplitude modulation signal S 2 is limited by the lower limit value limiting circuit 112 is input to the multiplier 109 via the switch 111. As a result, a signal obtained by multiplying the output of the variable gain amplifier 108 by the multiplier 109 and the signal in which the lower limit value of the amplitude fluctuation of the baseband amplitude modulation signal S2 is limited is obtained.

  FIG. 2 is a circuit configuration of the high frequency power amplifier 105 when used as a nonlinear amplifier, and FIG. 3 is a diagram showing the operation of the high frequency power amplifier 105 when used as a nonlinear amplifier. As shown in FIG. 2, the high frequency power amplifier 105 can be represented by a nonlinear amplifier 130 and a parasitic capacitance 131 connected between the input side and the output side thereof.

  FIG. 3 shows the relationship between the power supply voltage of the nonlinear amplifier 130 and the output power. As shown in FIG. 3, in the nonlinear amplifier 130, the square of the power supply voltage is proportional to the output power. Here, the magnitude of the leakage power is determined by the parasitic capacitance 131 and the level of the input signal of the nonlinear amplifier 130 (the level of the output signal of the multiplier 109).

  Here, considering the case where the variable gain amplifying unit 107 is not provided, since the output of the frequency synthesizer 106 is substantially constant, the leakage power is also constant. In that case, in order to lower the level of the transmission output signal S30, the power supply voltage of the non-linear amplifier 130 may be lowered. However, the output level cannot be lowered from a certain value due to the leakage power.

  On the other hand, in the present embodiment, by controlling the gain of the variable gain amplifier 108 by the gain control signal S12, the level of the high frequency phase modulation signal input to the high frequency power amplifier 105 is controlled, so that the leakage power is reduced. It can be reduced. Therefore, in the high frequency power amplifier 105, the control range of the output power by the power supply voltage can be expanded.

  Furthermore, by multiplying the output signal of the variable gain amplifier 108 by the baseband amplitude modulation signal S2 by the multiplier 109, the input level of the high frequency power amplifier 105 follows the instantaneous level fluctuation of the baseband amplitude modulation signal S2. In addition, since the leakage power is reduced, the reproducibility of the instantaneous level fluctuation can be improved. That is, the input of the high frequency power amplifier 105 can be controlled according to the instantaneous output power.

  Here, if the input level of the high-frequency power amplifier 105 is lowered too much, it deviates from the saturation operation or switching operation region, and the linearity with respect to the change in the power supply voltage deteriorates. Therefore, in this embodiment, by providing the lower limit limiting circuit 112, the input level of the high frequency power amplifier 105 is kept at a certain value or more. In the multiplier 109, the transmission output signal S30 is not subjected to amplitude modulation, but it is only necessary to reduce the leakage power by following the amplitude variation. Therefore, there is a problem even if the low level side of the instantaneous level variation is limited. Absent.

  Next, a case where the level of the transmission output signal S30 is relatively small will be described. First, in the switch 103, the terminal b and the terminal c are connected by the mode switching signal S10. As a result, the DC voltage value S11 is input to the amplitude modulation signal amplifier 104 via the switch 103, and a constant power supply voltage is applied to the high frequency power amplifier 105 from the amplitude modulation signal amplifier 104. As a result, the high frequency power amplifier 105 operates as a linear amplifier having a linear input / output relationship.

  On the other hand, for the high-frequency phase modulation signal S4, when the level of the transmission output signal S30 is relatively small, the baseband amplitude modulation in which the terminal b and the terminal c of the switch 111 are connected by the mode switching signal S10 and the lower limit value is not limited. The signal S2 is input to the multiplier 109. When the level of the transmission output signal S30 is relatively small, the gain offset signal S20 is set to zero, and the non-offset gain control signal S20 is input to the variable gain amplifier 108. The high frequency power amplifier 105 linearly amplifies the output of the multiplier 109 based on the fixed power supply voltage supplied from the amplitude modulation signal amplifier 104 to obtain a transmission output signal S30.

  As described above, in the polar modulation transmission apparatus 100 of the present embodiment, the level of the transmission output signal S30 is small and there is a possibility that the high-frequency power amplifier 105 is out of the saturation operation or switching operation region, that is, the power supply voltage Even in the case where the linearity of the output power with respect to the change may be deteriorated, the output power control range is expanded while maintaining the linearity of the output signal with respect to the input signal by operating the high-frequency power amplifier 105 as a linear amplifier. Can do.

  Thus, according to the present embodiment, when the level of the transmission output signal S30 is relatively high, the high-frequency power amplifier 105 is used as a nonlinear amplifier and the power supply voltage applied to the high-frequency power amplifier 105 is based on the baseband amplitude modulation signal. When the average output level control based on the instantaneous amplitude control and the gain control signal is performed and the level of the transmission output signal S30 is relatively small, the high-frequency power amplifier 105 is used as a linear amplifier and is provided in front of the high-frequency power amplifier 105. By controlling the instantaneous amplitude with the multiplier 109 and controlling the average output level with the variable gain amplifier 108 provided in the preceding stage of the multiplier 109, the level of the transmission output signal S30 can be controlled over a wide range. Can do.

  Further, when the high frequency power amplifier 105 is in a non-linear operation, the gain of the variable gain amplifier 108 is controlled in accordance with the gain control signal S12 to vary the level of the high frequency phase modulation signal S4. Therefore, the control range of the output power by the power supply voltage can be expanded.

  Furthermore, by multiplying the high frequency phase modulation signal S4 by the multiplier 109 with the baseband amplitude modulation signal S2, the input level of the high frequency power amplifier 105 follows the instantaneous level fluctuation of the baseband amplitude modulation signal S2 and the leakage power is also increased. Therefore, the reproducibility of the instantaneous level fluctuation based on the baseband amplitude modulation signal S2 can be improved.

  If the polar modulation transmitter 100 having the above characteristics is mounted on a portable radio terminal device, the high frequency power amplifier 105 operates as a non-linear amplifier at the time of high output power, thereby improving the power efficiency and reducing the battery consumption. Can be prevented and the use time can be extended. In addition, the high frequency power amplifier 105 can be reduced in size because the power efficiency is improved, and the amount of heat generated can be reduced, so that the portable wireless terminal device on which the high frequency power amplifier 105 is mounted can also be reduced in size.

  In addition, if the present invention is applied to a base station apparatus of a wireless system in which a plurality of high-power transmitters are installed, the power efficiency at the time of high output power of the high-frequency power amplifier is improved, so that the high-frequency power amplifier can be downsized. The amount of generated heat can be reduced, and as a result, the equipment can be prevented from becoming large and the space can be improved.

(Embodiment 2)
In this embodiment, there is proposed a polar modulation transmission apparatus having the same basic configuration as that of Embodiment 1 and capable of forming a transmission signal with higher quality by suppressing a transient response at the time of mode switching. To do.

(1) Overall Configuration FIG. 4 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 1 shows the configuration of the polar modulation transmission apparatus of the present embodiment. The polar modulation transmission apparatus 200 has the same configuration as the polar modulation transmission apparatus 100 of the first embodiment, except that the configuration of the amplitude control unit 201 is different from that of the polar modulation transmission apparatus 100 of the first embodiment. .

  The amplitude control unit 201 inputs the mode switching signal S10 and the gain control signal S12 to the calculation unit 202. Further, the total output power Pout is input to the calculation unit 202 via the instantaneous amplitude calculation unit 203. The instantaneous amplitude calculation unit 203 multiplies a baseband amplitude modulation signal (hereinafter referred to as an amplitude modulation signal) S2 (represents a relative value of the instantaneous amplitude value) and a gain control signal S12 (represents an average amplitude). The total output power Pout is obtained. Here, the total output power Pout means the power to be finally output from the high frequency power amplifier 105, and the input signal power Pin means the signal power of the high frequency phase modulation signal to be input to the high frequency power amplifier 105.

  The arithmetic unit 202 supplies the input signal power to be input to the high frequency power amplifier 105 (that is, the power to be output from the variable gain amplifier 107) Pin and the high frequency power amplifier 105 in accordance with the mode switching signal S10 and the total output power Pout. The power supply voltage Vccin to be calculated is calculated. Specifically, the arithmetic unit 202 has a lookup table as shown in FIGS. 5, 6, and 7, and uses this lookup table to calculate the input signal power Pin and the power supply voltage Vccin. Of these, the input signal power Pin is supplied to the variable gain amplifier 107 via the input signal amplitude controller 204, the variable gain amplifier amplitude controller 205 and the multiplier amplitude controller 206, and the power supply voltage Vccin is supplied via the power controller 207. To the high frequency power amplifier 105.

  The input signal amplitude control unit 204 extracts a low frequency component (corresponding to the component of the gain control signal S12) of the input signal power Pin, and sends it to the variable gain amplifier amplitude control unit 205. Further, the input signal amplitude control unit 204 extracts a high frequency component (corresponding to a component of the baseband amplitude modulation signal S2) of the input signal power Pin, and sends it to the multiplier amplitude control unit 206. The variable gain amplifier amplitude control unit 205 converts the input signal from digital to analog, and supplies a gain control signal S41 formed of an analog signal to the variable gain amplifier 108. Similarly, the multiplier amplitude control unit 206 performs digital-to-analog conversion on the input signal and supplies the instantaneous amplitude value S <b> 42 that is an analog signal to the multiplier 109.

  The power supply voltage value Vccin output from the calculation unit 202 is sent to the power supply control unit 207. The power supply control unit 207 generates a power supply voltage S43 corresponding to the power supply voltage value Vccin and supplies this to the high frequency power amplifier 105.

(2) Calculation of Input Signal Power Pin and Power Supply Voltage Vccin Next, how the calculation unit 202 calculates the input signal power Pin and the power supply voltage Vccin will be described in detail. The calculation method varies depending on each mode determined by the mode switching signal S10 and its history, and will be described separately for each mode.

(I) High-frequency power amplifier amplitude modulation mode as the first mode (that is, when the high-frequency power amplifier 105 is operated in a non-linear manner)
While looking at the high frequency power amplifier amplitude modulation mode in the look-up table of FIG. 7 (hereinafter referred to as the transient state control table), the input signal power Pin and the power supply voltage Vccin are determined according to the total output power Pout. Output. In this high frequency power amplifier amplitude modulation mode, basically, as described in the first embodiment, instantaneous amplitude fluctuations according to the baseband amplitude modulation signal are given by the non-linear operation of the high frequency power amplifier 105. Even if the instantaneous amplitude fluctuation component of the power Pin is changed, the change of the instantaneous amplitude fluctuation component in the total output power Pout is small (in other words, it is difficult to determine the input signal power Pin only from the total output power Pout). The input signal power Pin corresponding to the gain control signal is determined with reference to a table showing the relationship between the gain control signal gain (corresponding to the average amplitude fluctuation component) and the input signal power Pin shown in FIG. Next, with reference to the table of FIG. 7, the input signal power Pin is fixed to the determined column (state number), and the row corresponding to the total output power Pout is selected from this column, thereby corresponding to these. The power supply voltage Vccin to be determined is determined. That is, first, the input signal power Pin is determined according to the gain control signal S12, and then the power supply voltage Vccin is determined from the input signal power Pin and the total output power Pout.

(Ii) Variable gain amplifier amplitude modulation mode as the second mode (that is, when the high frequency power amplifier 105 is operated linearly)
The input signal power Pin and the power supply voltage Vccin are output according to the total output power Pout while looking at the variable gain amplifier amplitude modulation mode in the transient state control table of FIG. In this variable gain amplification unit amplitude modulation mode, the instantaneous amplitude variation corresponding to the baseband amplitude modulation signal S2 is given by the multiplier 109 of the variable gain amplification unit 107. Therefore, even if the instantaneous amplitude variation component of the power supply voltage Vccin is changed. Since the change in the instantaneous amplitude fluctuation component in the total output power Pout is small (in other words, it is difficult to determine the power supply voltage Vccin only from the total output power Pout), first, the gain control signal gain and the power supply voltage Vccin shown in FIG. The power supply voltage Vccin corresponding to the gain control signal S12 is determined with reference to the table showing the relationship. Next, referring to the table of FIG. 7, the power supply voltage Vccin is fixed to the determined column (state number), and the row corresponding to the total output power Pout is selected from the column, and the corresponding input is selected. The signal power Pin is determined. That is, first, the power supply voltage Vccin corresponding to the gain control signal S12 is determined, and then the input signal power Pin is determined from the power supply voltage Vccin and the total output power Pout.

(Iii) At the time of the amplitude modulation switching mode as the third mode While moving the column (state number) at the time of the amplitude modulation switching mode in the transient state control table of FIG. 7 from right to left or from left to right The input signal power Pin and the power supply voltage Vccin are output according to the total output power Pout. At this time, the initial column (state number) and the end column (state number) are the columns in the above two modes (state number). Here, there are actually two types of switching of the amplitude modulation mode: switching from the variable gain amplification unit amplitude modulation mode to the high frequency power amplifier amplitude modulation mode and switching from the high frequency power amplifier amplitude modulation mode to the variable gain amplification unit amplitude modulation mode. is there. Each of these two switching operations will be described below.

(Iii-1) Switching from Variable Gain Amplifier Amplitude Modulation Mode to High Frequency Power Amplifier Amplitude Modulation Mode As shown in FIG. 9, while continuously increasing the amplitude of the input signal power Pin to a predetermined level as shown in FIG. The power supply voltage Vccin is continuously lowered from a predetermined fixed level. Incidentally, the dotted line in FIGS. 8-11 shows the average amplitude corresponding to the gain control signal S12.

(Iii-2) Switching from High Frequency Power Amplifier Amplitude Modulation Mode to Variable Gain Amplifier Amplitude Modulation Mode As shown in FIG. 11, the amplitude of the input signal power Pin is continuously lowered from a predetermined level as shown in FIG. The power supply voltage Vccin is continuously raised to a predetermined fixed level.

(3) Creation of Transient State Control Table Next, how to create the transient state control table shown in FIG. 7 will be described.

  First, in the connection state shown in FIG. 4, the output power from the high frequency power amplifier 105 (this corresponds to the total output power Pout) is measured while changing the input signal power Pin and the power supply voltage Vccin. That is, the data of the following formula is collected.

Pout = f (Pin, Vccin) (4)
Thereby, a contour map as shown in FIG. 12 can be obtained.

  Next, based on this, the relationship of the following equation is obtained.

Vccin = g (Pout, Pin) (5)
If the mode is switched when the total output power Pout does not change, the total output power Pout is constant. Therefore, if the input signal power Pin is determined, the value of the power supply voltage Vccin is determined.

  However, in the high frequency power amplifier amplitude modulation mode, even if the input signal power Pin is changed, the change in the power supply voltage Vccin is small. Therefore, the value of the input signal power Pin in this mode is shown in the table of FIG. To determine. Specifically, the input signal power Pin is determined by a gain control signal (gain).

  On the other hand, in the variable gain amplifying unit amplitude modulation mode, even if the power supply voltage Vccin is changed, the change in the total output power Pout is small. Therefore, the value of the power supply voltage Vccin in this mode is shown in the table of FIG. To determine.

  Incidentally, the input signal power Pin is determined by the output amplitude of the frequency synthesizer 106 used as the phase modulation unit, the gain of the variable gain amplifier 108, and the gain of the multiplier 109. The gain of the variable gain amplifier 108 and the gain of the multiplier 109 are determined by the gain control signal S41 from the variable gain amplifier amplitude control unit 205 and the instantaneous amplitude value S42 from the multiplier amplitude control unit 206, respectively. Therefore, the variable gain amplifier amplitude control unit 205 and the multiplier amplitude control unit 206 may also collect data so that the gain requested in the total output signal Pout is more accurately reproduced.

  A table showing the contour map of FIG. 12 is the transient state control table of FIG. Returning to the contour diagram, in the high frequency power amplifier amplitude modulation mode, the input signal power Pin and the power supply voltage Vccin on the A-A ′ line (or the upper side of the figure) are selected. On the other hand, in the variable gain amplification unit amplitude modulation mode, the input signal power Pin and the power supply voltage Vccin on the B-B ′ line (or the right side in the drawing) are selected. In the amplitude modulation switching mode, the total output power Pout between the A-A ′ line and the B-B ′ line moves on a constant contour line.

  Here, in the high frequency power amplifier amplitude modulation mode, the change in the total output power Pout is small even if the input signal power Pin is changed, and it can be seen from the contour map that the total output power Pout changes when the power supply voltage Vccin is changed. . On the other hand, in the variable gain amplification unit amplitude modulation mode, the change in the total output power Pout is small even when the power supply voltage Vccin is changed. From the contour map, the total output power Pout changes when the input signal power Pin is changed. I understand.

(4) Operation of Embodiment Next, the mode switching operation of the present embodiment will be described with reference to FIGS. Incidentally, the arithmetic unit 202 has a CPU (Central Processing Unit) configuration having the lookup tables of FIGS.

  First, when processing is started in step ST0, various initial values are set in step ST1. Specifically, an initial value setting of a mode change flag (mode change flag), an initial value setting of a column number (state number) in FIG. 7, and an initial value setting of a column number (target state number) after mode switching is completed. And the initial value of the previous mode switching signal (mode old).

  Next, data input processing is performed in step ST2. Specifically, a mode switching signal (mode), a gain control signal (gain), and a total output power (Pout) are input.

  In the next step ST3, it is determined whether or not the current mode is the high frequency power amplifier amplitude modulation mode. If the current mode is not the high frequency power amplifier amplitude modulation mode (that is, the variable gain amplifier amplitude modulation mode), the process proceeds to step ST4. In the case of the high frequency power amplifier amplitude modulation mode, the process proceeds to step ST5. In step ST4 and step ST5, the process of determining the target state number is performed, but the contents of the process are different. That is, in step ST4, the power supply voltage (Vccin) is first determined from the gain control signal (gain) with reference to FIG. 6, and then the power supply voltage (Vccin) and the total output power (Pout) are determined with reference to FIG. Determine the corresponding column (target state number). On the other hand, in step ST5, the input signal power (Pin) is first determined from the gain control signal (gain) with reference to FIG. 5, and then the input signal power (Pin) and the combined output are referred to with reference to FIG. A column (target state number) corresponding to the signal (Pout) is determined.

  In step ST6, it is determined whether or not a mode change flag is set. If the flag is set, the process proceeds to step ST7. If not, the process proceeds to step ST8.

  In step ST8, it is determined whether or not the mode (mode) instructed by the current mode switching signal S10 is the same as the mode (mode old) one clock previous held by the calculation unit 202 itself. In step ST9, the mode switching flag is updated to a value (true) representing the state of the amplitude modulation switching mode, and then the process proceeds to step ST7. On the other hand, when the mode (mode) instructed by the current mode switching signal S10 is the same as the mode (mode old) one clock previous held by the calculation unit 202 itself, this is the mode switching state. Therefore, in step ST10, the column number (state number) is set to the column number (target state number) at which mode switching ends, and the process proceeds to step ST15.

  In step ST7, it is determined whether or not the current mode switching signal is in the high frequency power amplifier amplitude modulation mode. If the current mode switching signal is not in the high frequency power amplifier amplitude modulation mode, the process proceeds to step ST11 and the column number (state number) is decreased by one. Move the column in FIG. 7 one place to the left. On the other hand, in the case of the high frequency power amplifier amplitude modulation mode, the process moves to step ST12 and the column number in FIG. 7 is moved to the right by incrementing the column number (state number) by one.

  In the following step ST13, it is determined whether or not the column number is the column number for mode switching end. If a negative result is obtained, the process proceeds to step ST15. If an affirmative result is obtained, the mode switching flag is set in step ST14. After changing to a value (false) representing a state not in the amplitude modulation switching mode, the process proceeds to step ST15.

  In the following step ST15, it is stored in the row corresponding to the total output signal (Pout) input in step ST2 and the column (state number) set in step ST11, ST12 or ST10 in the transient state control table of FIG. The input signal power Pin and the power supply voltage Vccin are output. In subsequent step ST16, the mode (mode old) one clock before is changed to the current mode (mode), and the process returns to step ST2.

  As described above, in the polar modulation transmission apparatus 200, the total output power Pout to be input and the high frequency power amplifier amplitude modulation mode, the variable gain amplification unit amplitude modulation mode, and the amplitude modulation switching mode are used as addresses, and the total output power Pout is obtained. Using the transient state control table in which the values allocated to the high frequency power amplifier and the variable gain amplifier are stored in association with each address, the gain of the variable gain amplifier 107 is increased, and the gain of the high frequency power amplifier 105 is The total output power Pout is distributed and supplied to the variable gain amplification unit 107 and the high frequency power amplifier 105 so that the lowering action is balanced.

  As a result, mode switching between the high-frequency power amplifier amplitude modulation mode and the variable gain amplification unit amplitude modulation mode can be performed continuously and gradually, so that a transient response can be suppressed and a good transmission output signal S40 can be obtained even during mode switching. Can be formed. As a result, when the polar modulation transmission apparatus 200 is mounted on, for example, a mobile phone, it is possible to ensure call quality at the time of mode switching.

  Here, in FIGS. 15 to 18, the input signal power Pin and the power supply voltage Vccin when the mode is switched instantaneously using the switches 103 and 111, for example, as shown in FIG. 1 without providing the amplitude modulation switching mode. Show the state. FIG. 15 shows the state of the input signal power Pin to the variable gain amplifier when switching from the variable gain amplifier amplitude modulation mode to the high frequency power amplifier amplitude modulation mode, and FIG. 16 shows the state of the power supply voltage Vccin to the high frequency power amplifier. Shown in FIG. 17 shows the state of the input signal power Pin to the variable gain amplifier when switching from the high frequency power amplifier amplitude modulation mode to the variable gain amplifier amplitude modulation mode, and FIG. 17 shows the state of the power supply voltage Vccin to the high frequency power amplifier. 18 shows. When the mode is switched instantaneously in this way, the input signal power Pin and the power supply voltage Vccin change abruptly when the mode is switched, so that a transient response occurs. As a result, the quality of the transmission output signal S30 (for example, EVM (error vector magnitude)) ). Incidentally, the dotted line in FIGS. 15 to 18 shows the average amplitude corresponding to the gain control signal S12.

  For example, in the W-CDMA standard, since a communication terminal basically transmits data at all times, it is necessary to perform the mode switching described above when transmitting data. In this case, if polar modulation transmission apparatus 200 according to the present embodiment is used, it is possible to suppress degradation of EVM at the time of mode switching, and therefore it is possible to suppress degradation of data error rate characteristics.

  Thus, according to the present embodiment, in addition to the high frequency power amplifier amplitude modulation mode and the variable gain amplification unit amplitude modulation mode, the distribution Pin, Vccin of the total output power Pout to the variable gain amplification unit 107 and the high frequency power amplifier 105 is set. By providing an amplitude modulation switching mode that is continuously changed when changing from one mode to the other mode, it is possible to obtain a good transmission output signal S40 while suppressing a transient response at the time of mode switching. The polar modulation transmission apparatus 200 can be realized.

  In this embodiment, the case where the mode is switched using the look-up tables as shown in FIGS. 5 to 7 has been described. However, the same can be realized by a calculation using a function.

  In this embodiment, the variable gain amplifying unit 107 is configured by the variable gain amplifier 108 and the multiplier 109. However, the configuration of the variable gain amplifying unit is not limited to this, and the main point is that the high frequency phase modulation signal is used. Any configuration that can change the amplitude of S4 according to the amplitude modulation signal may be used.

  In this embodiment, the case where the signal for changing the amplitude of the high-frequency phase modulation signal S4 is the total output power Pout obtained by multiplying the amplitude modulation signal S2 by the gain control signal S12 has been described. The signal for changing the amplitude may be only the amplitude modulation signal S2. In short, it can be widely applied to the case where the amplitude of the oscillation high frequency phase modulation signal S4 is changed according to the amplitude modulation signal S2.

  The present invention is suitable for application to a wireless communication apparatus such as a portable information terminal or a wireless base station.

The block diagram which shows the structure of the polar modulation transmission apparatus which concerns on Embodiment 1 of this invention. The figure which shows the circuit structure at the time of using the high frequency power amplifier shown in FIG. 1 as a nonlinear amplifier. The figure explaining operation | movement at the time of using the high frequency power amplifier shown in FIG. 1 as a nonlinear amplifier FIG. 3 is a block diagram illustrating a configuration of a polar modulation transmission apparatus according to a second embodiment. The figure for explanation of the mode of the second embodiment The figure for explanation of the mode of the second embodiment Diagram for explaining the transient state control table The figure which shows the change of the input signal electric power Pin to a variable gain amplification part at the time of switching from a variable gain amplification part amplitude modulation mode to a high frequency power amplifier amplitude modulation mode The figure which shows the change of the power supply voltage Vccin to a high frequency power amplifier at the time of switching from a variable gain amplifier part amplitude modulation mode to a high frequency power amplifier amplitude modulation mode The figure which shows the change of the input signal electric power Pin to the variable gain amplification part at the time of switching from high frequency power amplifier amplitude modulation mode to variable gain amplification part amplitude modulation mode The figure which shows the change of the power supply voltage Vccin to a high frequency power amplification part at the time of switching from a high frequency power amplifier amplitude modulation mode to a variable gain amplification part amplitude modulation mode The figure which shows the relationship between the total output electric power Pout in each mode, the input signal electric power Pin, and the power supply voltage Vccin. Flowchart for explaining mode switching operation according to Embodiment 2 Flowchart for explaining mode switching operation according to Embodiment 2 The figure which shows the change of the input signal electric power Pin to the variable gain amplification part at the time of switching from the variable gain amplification part amplitude modulation mode to the high frequency power amplifier amplitude modulation mode instantaneously The figure which shows the change of the power supply voltage Vccin to a high frequency power amplifier at the time of switching from a variable gain amplifier part amplitude modulation mode to a high frequency power amplifier amplitude modulation mode instantaneously The figure which shows the change of the input signal electric power Pin to the variable gain amplification part at the time of switching from the high frequency power amplifier amplitude modulation mode to the variable gain amplification part amplitude modulation mode instantaneously The figure which shows the change of the power supply voltage Vccin to a high frequency power amplification part at the time of switching from a high frequency power amplifier amplitude modulation mode to a variable gain amplification part amplitude modulation mode instantaneously Block diagram showing the configuration of a conventional polar modulation transmitter

Explanation of symbols

100, 200 Polar modulation transmitter 105 High frequency power amplifier 107 Variable gain amplifier 120, 201 Amplitude controller S1 Baseband modulation signal S2 Baseband amplitude modulation signal S3 Baseband phase modulation signal S4 High frequency phase modulation signal S10 Mode switching signal S12 Gain Control signal S30, S40 Transmission output signal Pout Total output power Pin Input signal power Vccin Power supply voltage

Claims (4)

A high frequency power amplifier that changes the amplitude of the high frequency phase modulation signal in accordance with the amplitude modulation signal;
A variable gain amplifier provided on the front side of the high-frequency power amplifier;
A first mode in which the amplitude modulation signal is assigned to the high frequency power amplifier; a second mode in which the amplitude modulation signal is assigned to the variable gain amplification unit; and the amplitude in both the high frequency power amplifier and the variable gain amplification unit. A third mode for allocating and allocating the modulation signal, and applying the amplitude fluctuation to the high-frequency phase modulation signal based on the amplitude modulation signal by the high-frequency power amplifier and / or the variable gain amplification unit A polar modulation transmission apparatus, comprising: an amplitude control unit that controls whether the signal is given by When the mode is switched from the first mode to the second mode, or when the mode is switched from the second mode to the first mode, the amplitude control unit is configured to pass through the third mode. The polar modulation transmission apparatus according to claim 1, wherein mode switching is performed. The amplitude control unit uses the input amplitude modulation signal and the first, second, and third modes as addresses, and distributes the input amplitude modulation signal to the high-frequency power amplifier and the variable gain amplification unit. The polar modulation transmission apparatus according to claim 2, further comprising a transient state control table in which the obtained values are stored in association with the respective addresses. A high frequency power amplifier amplitude modulation step for changing the amplitude of the high frequency phase modulation signal according to the amplitude modulation signal using the high frequency power amplifier;
A variable gain amplification unit amplitude modulation step for changing the amplitude of the high-frequency phase modulation signal according to the amplitude modulation signal using a variable gain amplification unit;
The amplitude modulation signal is distributed to both the high frequency amplifier and the variable gain amplification unit, and the amplitude of the high frequency phase modulation signal is changed to the amplitude modulation signal using both the high frequency power amplifier and the variable gain amplification unit. A polar modulation method comprising: an amplitude modulation switching step that changes in response.

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