JP2005269440A - Polar modulation transmitter and polar modulation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polar modulation transmitter capable of obtaining a phase-amplitude synthesis signal of good quality with small distortion, in addition to a satisfactory power efficiency and a wide control range of transmission output power (phase-amplitude synthesis signal). <P>SOLUTION: With the provision of predistortion sections 105, 108, the content of predistortion processing executed in either the predistortion section 105 or 108 is switched, depending on a mode of phase/amplitude synthesis to be performed in whether a high-frequency power amplifier circuit 107 or a variable gain amplifier circuit 109. Thus, in addition to the inherent predistortion processing, predistortion processing for restricting distortion produced in the other circuit 107 or 109 is performed complementarily. As a result, as compared with the predistortion simply performed to the target circuit only, distortion finally produced in the phase/amplitude synthesis signal V (RF, PA) can be restricted further. <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. 9, this polar modulation transmission apparatus includes an amplitude phase separation unit 10, an amplifier 11, a phase modulation unit 12, and a high frequency power amplifier 13 as a phase amplitude synthesis unit. The high frequency power amplifier 13 is a non-linear amplifier.

  The amplitude phase separation unit 10 receives the baseband signal S1, and separates it into an amplitude component signal S2 and a phase component signal S3. The amplitude component signal S2 is supplied to the nonlinear high-frequency power amplifier 13 via the amplifier 11 as a power supply voltage for the high-frequency power amplifier 13. The phase component signal S3 is input to the phase modulation unit 12. The phase modulation unit 12 obtains a high frequency phase modulation signal S4 by phase modulating the carrier wave signal with the phase component signal S3, and sends this to the high frequency power amplifier 13. Thus, the high frequency power amplifier 13 amplifies the high frequency phase modulation signal S4 based on the power supply voltage corresponding to the amplitude component signal S2 to synthesize the phase amplitude, and outputs this as a transmission output signal (phase amplitude synthesis signal) S5. To do.

  Next, the operation of the polar modulation transmission apparatus will be described. First, if the baseband 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 component signal S2, and the phase data exp [jφ (t)] corresponds to the phase component signal S3. The amplitude data a (t) is amplified and current-enhanced by the amplifier 11 based on information such as transmission average power, and is supplied to the high-frequency power amplifier 13. Thus, the power supply voltage value of the high-frequency power amplifier 13 is obtained by multiplying the amplitude data a (t) and the transmission average power (= Ga (t), G depends on the transmission average power).

  The phase modulator 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 = exp [j (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 Ga (t) of the high frequency power amplifier 13 and the output signal of the phase modulation unit 12 is a transmission output signal of the high frequency power amplifier 13. S5. 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) exp [j (ωct + φ (t))] (3)
The high-frequency phase signal S4 input to the high-frequency power amplifier 13 is a phase-modulated signal having no fluctuation component in the amplitude direction, and thus 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 average output signal level is controlled only by the high frequency power amplifier 13, the control range of the output power depends on the operation limit of the transistor with respect to the leakage power and the power supply voltage. There was a problem that the dynamic range could not be widened. In addition, there is a problem that nonlinear distortion in the high-frequency power amplifier 13 is not sufficiently suppressed.

  The present invention has been made in view of the above points, and in addition to having a good power efficiency and a wide control range of transmission output power (phase amplitude composite signal), a phase amplitude composite signal having a good quality with little distortion is provided. An object is to provide a polar modulation transmission apparatus and a polar modulation method that can be obtained.

  In order to solve this problem, a polar modulation transmission apparatus of the present invention includes a high-frequency power amplifier that amplifies a high-frequency phase modulation signal, a variable gain amplifier that is provided on the front side of the high-frequency power amplifier and amplifies the high-frequency phase modulation signal, and high-frequency power. A first predistortion unit that compensates a power supply voltage supplied to the amplifier, and a second predistortion unit that compensates a gain control signal supplied to the variable gain amplifier. A first mode for synthesizing the phase of the modulation signal and the amplitude component signal, and a second mode for synthesizing the phase and amplitude of the high frequency phase modulation signal and the amplitude component signal by the variable gain amplifier. The distortion unit forms a power supply voltage and a gain control signal that complementarily compensate for distortion of the phase / amplitude composite signal in each mode. Take the deposition.

  According to this configuration, the variable gain amplifier is provided on the front stage side of the high frequency power amplifier, and it is selected whether the phase amplitude synthesis is performed by the high frequency power amplifier or the variable gain amplifier depending on the mode. While maintaining high power efficiency in the amplifier, the dynamic range of the phase / amplitude composite signal can be widened, and the control range of the transmission output power can be widened.

  In addition, since the first and second predistortion units complementarily compensate for distortion of the phase / amplitude composite signal in each mode, the power supply voltage of the high-frequency power amplifier is simply calculated by the first predistortion unit. As compared with the case where the gain control signal of the variable gain amplifier is compensated by the second predistortion unit, adaptive predistortion processing corresponding to each mode can be performed, and distortion compensation accuracy can be performed. As a result, it is possible to obtain a phase / amplitude synthesized signal with good quality.

  In the polar modulation transmission apparatus according to the present invention, in the first mode, the first predistortion unit compensates for the amplitude component signal in consideration of the distortion characteristics of the high frequency power amplifier and forms a power supply voltage to be supplied to the high frequency power amplifier. In addition, the second predistortion unit takes a configuration in which a gain control signal is supplied in consideration of the linearity of phase amplitude synthesis in the high frequency power amplifier.

  According to this configuration, in the phase amplitude synthesis by the high frequency power amplifier, in addition to the distortion compensation effect by the first predistortion unit, the linearity from the variable gain amplifier to the high frequency power amplifier is improved by the second predistortion unit. Since gain adjustment is performed so as to obtain an output that can be maintained, a high-frequency power amplifier can obtain a phase-amplitude synthesized signal with very little distortion.

  In the polar modulation transmission apparatus of the present invention, in the second mode, the first predistortion unit supplies a power supply voltage obtained by envelope following the amplitude component signal, and the second predistortion unit is a distortion of the variable gain amplifier. A configuration is adopted in which a gain control signal supplied to the variable gain amplifier is formed by compensating for the amplitude component signal in consideration of the characteristics.

  According to this configuration, the distortion is compensated by the second predistortion unit and the distortion in the high-frequency power amplifier is compensated by the first predistortion unit when phase amplitude synthesis is performed by the variable gain amplifier. In this case, so that the so-called back-off in the high frequency power amplifier can be minimized by enveloping the power supply voltage applied to the high frequency power amplifier, so that the power efficiency in the high frequency power amplifier is maximized, In addition, a phase / amplitude synthesized signal with very little distortion is output.

  The polar modulation transmission apparatus of the present invention further includes a third predistortion unit that compensates and supplies the phase component signal to the phase modulation unit that forms the high frequency phase modulation signal from the phase component signal. In the first mode, the distortion section compensates for distortion characteristics caused by phase amplitude synthesis by the high-frequency power amplifier, and in the second mode, the distortion section compensates for distortion characteristics caused by phase amplitude synthesis by the variable gain amplifier.

  According to this configuration, it is possible to obtain a phase / amplitude composite signal with much less distortion.

  The polar modulation transmission apparatus of the present invention employs a configuration in which the compensation processing of each predistortion unit is adjusted based on the output of the high frequency power amplifier and / or the output of the variable gain amplifier.

  According to this configuration, even when the distortion characteristics of the high-frequency power amplifier and the variable gain amplifier change due to temperature and aging, this distortion can be compensated for by each predistortion unit.

  The polar modulation transmission apparatus of the present invention employs a configuration including a delay adjustment unit that performs synchronization adjustment at the time of phase amplitude synthesis by delaying an amplitude component signal and / or a phase component signal.

  According to this configuration, it is possible to reduce distortion at the time of phase amplitude synthesis caused by a delay difference in the path of the amplitude component signal and the phase component signal, so that a better phase amplitude synthesis signal can be obtained. .

  The polar modulation transmission apparatus of the present invention employs a configuration in which each predistortion unit performs different compensation processing depending on the modulation scheme or the transmission frequency band.

  According to this configuration, since predistortion processing suitable for the modulation scheme and transmission signal band can be performed, even when the modulation scheme and transmission signal band are switched, good distortion compensation can be performed. become able to.

  In the first mode, the polar modulation method of the present invention combines the phase amplitude of the high frequency phase modulation signal and the amplitude component signal by the high frequency power amplifier, and is provided on the front side of the high frequency power amplifier in the second mode. A phase amplitude combining step for combining the high frequency phase modulation signal and the amplitude component signal with a variable gain amplifier, and in the first mode, the distortion component of the high frequency power amplifier is added to compensate for the amplitude component signal in the high frequency power amplifier. Forming a supply voltage to be supplied and supplying a gain control signal to the variable gain amplifier so that the linearity of the phase amplitude synthesis in the high frequency power amplifier is maintained; and in the second mode, the amplitude component signal is envelope-followed Power supply voltage is supplied to the high-frequency power amplifier, and the amplitude component signal is compensated by taking into account the distortion characteristics of the variable gain amplifier. A gain control signal to form as and supplying to the variable gain amplifier.

  According to this method, it is selected whether the phase / amplitude synthesis is performed by the high-frequency power amplifier or the variable gain amplifier according to the mode, so that it is possible to obtain a phase / amplitude synthesized signal having high power efficiency and a wide dynamic range. it can. In addition, distortion compensation is performed for each mode in a complementary manner with respect to the high frequency power amplifier and variable gain amplifier. Therefore, in all modes, the burden of distortion compensation for the high frequency power amplifier and variable gain amplifier can be optimally shared. It is possible to obtain a phase / amplitude composite signal with very little distortion.

  As described above, according to the present invention, polar modulation capable of forming a transmission signal (phase amplitude synthesized signal) with low distortion and high quality in addition to good power efficiency and a wide control range of transmission output power. A transmitter 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 the configuration of a polar modulation transmission apparatus according to Embodiment 1 of the present invention. Polar modulation transmission apparatus 100 inputs I (in-phase) component and Q (quadrature) component of baseband signal S10 to amplitude phase separation section 101. The amplitude phase separation unit 101 separates the baseband signal S10 into an amplitude component signal S11 and a phase component signal S12, sends the amplitude component signal S11 to the multiplier 102, and outputs the phase component signal S12 via the predistortion unit 103. The data is sent to the modulation unit 104. The phase modulation unit 104 is a frequency synthesizer, for example, and modulates the carrier frequency signal with the predistorted phase component signal to form the high frequency phase modulation signal S13.

  On the other hand, the amplitude component signal S11 input to the multiplier 102 is multiplied by the average output power control signal S20 in the multiplier 102 to be an amplitude control signal S22 corresponding to the instantaneous amplitude (envelope) component signal.

  The amplitude control signal S22 is set to the power supply voltage V (PA) of the high frequency power amplifier 107 through the predistortion unit 105 and the amplifier 106, and is supplied to the high frequency power amplifier 107. The amplitude control signal S22 is converted into a gain control signal V (VGA) of the variable gain amplifier 109 via the predistortion unit 108 and supplied to the variable gain amplifier 109.

  In polar modulation transmission apparatus 100 of the present embodiment, variable gain amplifier 109 is provided in front of high-frequency power amplifier 107, so that a block that performs phase amplitude synthesis in accordance with the level of transmission output power is constituted by these two amplifiers. Can be shared. As a result, the dynamic range of the phase amplitude synthesized signal can be widened and the control range of the transmission output power can be widened as compared with the case where the average output power and the instantaneous amplitude are adjusted only by the high frequency power amplifier 107. Can do.

  Specifically, in the first mode (for example, when a high level transmission output power is obtained (that is, when a high level transmission output is specified by the average output power control signal S20), the predistortion unit 108 By designating an optimum gain value for the variable gain amplifier 109 (such that the linearity of phase amplitude synthesis by the subsequent high-frequency power amplifier 107 is maximized) by the gain control signal V (VGA) of 107 is operated as a non-linear amplifier, and the transmission power controlled instantaneous amplitude fluctuation based on the amplitude component signal S11 and the average output power control signal S20 is given by the high frequency power amplifier 107. That is, the high frequency power amplifier 107 performs phase amplitude synthesis. Thereby, the power efficiency can be remarkably improved.

  On the other hand, in the second mode (for example, when low level transmission output power is obtained (that is, when low level transmission power is specified by the average output power control signal S20)), the high frequency power amplifier 107 is used. Is operated as a linear amplifier, and the variable gain amplifier 109 gives instantaneous amplitude fluctuation based on the amplitude component signal S11 and the average output power control signal S20. That is, phase amplitude synthesis is performed by the variable gain amplifier 109.

  Thus, in the polar modulation transmission apparatus 100, the variable gain amplifier 109 is provided on the upstream side of the high frequency power amplifier 107, and it is selected whether the phase amplitude synthesis is performed by the high frequency power amplifier 107 or the variable gain amplifier 109 depending on the mode. As a result, the dynamic range of the phase / amplitude composite signal V (RF, PA) can be widened, and the high-frequency power amplifier 107 is operated in a nonlinear amplifier or envelope follow according to the mode, so that the power efficiency is kept high. be able to.

  In this embodiment, the predistortion units 103, 105, and 108 are mainly configured by a CPU (Central Processing Unit) and a lookup table accessed by the CPU.

  In practice, each predistortion unit 103, 105, 108 receives an operation mode switching signal S21 in addition to the signal to be compensated, and the predistortion units 103, 105, 108 perform different compensation processes depending on the operation mode. To do. In the case of this embodiment, each predistortion unit 103, 105, 108 has a look-up table for performing predistortion processing corresponding to the operation mode. Predistortion processing is executed.

  Hereinafter, the configuration and operation of the predistortion units 103, 105, and 108 will be described in detail with reference to FIGS. In FIG. 2, the predistortion is abbreviated as PD.

  As shown in FIG. 2, when the polar modulation transmission apparatus 100 starts polar modulation transmission processing in step ST0, the average output power control signal S20 is input to each predistortion unit 103, 105, 108 in step ST1, and step ST2 Then, the operation mode switching signal S21 is input to each predistortion unit 103, 105, 108.

  In the subsequent step ST3, each predistortion unit 103, 105, 108 determines whether or not the high-frequency power amplifier 107 is in a mode of phase / amplitude synthesis based on the operation mode switching signal S21 input in step ST2. If a positive result is obtained in step ST3, the process proceeds to step ST4. If a negative result is obtained, the process proceeds to step ST5.

  First, the processing of each predistortion unit 103, 105, 108 in step ST4 will be described.

  In this case, the phase / amplitude synthesis is performed by the high-frequency power amplifier 107, and the predistortion unit 105 gives distortion opposite to the distortion characteristic of the high-frequency power amplifier 107 to the amplitude control signal S22. Predistortion processing for the amplifier 107 is performed and output. As a result, the power supply voltage V (PA) compensated for distortion is output from the amplifier 106.

  The predistortion unit 108 forms a gain control signal V (VGA) based on the average output power control signal S20. At this time, the gain control signal V that optimizes the linearity of phase amplitude synthesis in the high-frequency power amplifier 107 is obtained. (VGA) is output. In other words, this corresponds to complementary compensation for distortion compensation at the time of phase amplitude synthesis in the high-frequency power amplifier 107 even in the amplification processing in the variable gain amplifier 109.

  In practice, the predistortion unit 108 has a look-up table in which a gain control signal V (VGA) corresponding to the designated average output power control signal S20 is stored, and the gain control signal V is used using this look-up table. (VGA) is formed. Pin in FIG. 3 indicates the output power of the variable gain amplifier 109 whose gain is controlled according to the gain control signal V (VGA). Vcc in the figure indicates a power supply voltage value to be supplied to the high-frequency power amplifier 107, which is indicated by the amplitude control signal S22. The gain of the variable gain amplifier 109 is set by the output from the predistortion unit 108, that is, the predistortion unit 108 corresponds to a desired output power among a plurality of curves corresponding to each Pin shown in FIG. 3. Thus, an optimum curve that minimizes the distortion is selected, and the high-frequency power amplifier 107 performs phase amplitude synthesis according to the output power-Vcc characteristic indicated by the designated curve. Thereby, the predistortion unit 108 supplementarily suppresses distortion at the time of phase amplitude synthesis in the high frequency power amplifier 107.

  In the mode in which the high-frequency power amplifier 107 performs phase / amplitude synthesis, the predistortion unit 103 compensates for distortion characteristics generated by the phase / amplitude synthesis by the high-frequency power amplifier 107 and also performs the phase / amplitude synthesis by the variable gain amplifier 109. In the case of (corresponding to step ST5 described later), distortion characteristics generated by phase amplitude synthesis by the variable gain amplifier 109 are compensated. That is, the predistortion unit 103 has two types of predistortion modes. In step ST4, the predistortion mode that compensates for distortion when the phase amplitude is synthesized by the high-frequency power amplifier 107 is selected, and the phase component signal S12 is selected. On the other hand, compensation is performed in consideration of distortion at the time of phase amplitude synthesis in the high-frequency power amplifier 107, and the compensated phase component signal V (ph) is output.

  Next, processing of each predistortion unit 103, 105, 108 in step ST5 will be described.

  In this case, the phase / amplitude synthesis is performed by the variable gain amplifier 109, and the predistortion unit 108 gives the amplitude control signal S22 a distortion having a characteristic opposite to the distortion characteristic of the variable gain amplifier 109. A predistortion process is performed on the amplifier 109 to output a gain control signal V (VGA).

  The predistortion unit 105 outputs a power supply voltage for causing the high frequency power amplifier 107 to perform an envelope follow operation as a power source for the high frequency power amplifier 107. Thereby, the back-off of the high-frequency power amplifier 107 is kept constant, and as a result, the power efficiency of the high-frequency power amplifier 107 can be maximized.

  The predistortion unit 103 selects a predistortion mode for compensating for distortion when the phase / amplitude synthesis is performed by the variable gain amplifier 109, and performs distortion upon phase / amplitude synthesis by the variable gain amplifier 109 with respect to the phase component signal S12. Compensation with consideration is performed and the phase component signal V (ph) after compensation is output.

  As described above, in the polar modulation transmission apparatus 100, when phase amplitude synthesis is performed by either the variable gain amplifier 109 or the high frequency power amplifier 107, distortion compensation is also complementarily performed in the other path where phase amplitude synthesis is not performed. Alternatively, since power supply voltage control is performed, distortion compensation accuracy and power efficiency can be improved.

  For example, when phase amplitude synthesis is performed by the variable gain amplifier 109, even if the high-frequency power amplifier 107 is used as a linear amplifier, a certain amount of distortion occurs due to the high-frequency power amplifier 107, but this distortion is predistortion unit 105. Since pre-distortion processing is performed, it can be suppressed. In addition, since the envelope follow is performed in the predistortion unit 105, the power efficiency can be improved.

  On the other hand, when phase / amplitude synthesis is performed by the high-frequency power amplifier 107, the predistortion unit 108 for the variable gain amplifier 109 can provide an output that maintains the linearity of the high-frequency power amplifier 107 from the variable gain amplifier. Since such gain adjustment is performed, the high-frequency power amplifier 107 can obtain the phase / amplitude synthesized signal V (RF, PA) with very little distortion.

  FIG. 4 shows an output waveform of each part of the polar modulation transmission apparatus 100. A period between the time point t1 and the time point t2 is a period in which the phase amplitude synthesis is performed by the variable gain amplifier 109, and the other period is a period in which the phase amplitude synthesis is performed by the high frequency power amplifier 107.

  According to the present embodiment, the variable gain amplifier 109 is provided on the upstream side of the high frequency power amplifier 107, and it is selected whether the phase amplitude synthesis is performed by the high frequency power amplifier 107 or the variable gain amplifier 109 depending on the mode. Therefore, the dynamic range of the phase / amplitude composite signal can be widened and the control range of the transmission output power can be widened while keeping the power efficiency of the high-frequency power amplifier 107 high.

  In addition, predistortion units 105 and 108 are provided, and the content of predistortion processing is switched depending on whether each predistortion unit 105 or 108 performs phase amplitude synthesis in the high frequency gain amplifier 107 or the variable gain amplifier 109. The power supply voltage V (PA) and the gain control signal V (VGA) for compensating for the distortion of the phase / amplitude composite signal in a complementary manner in each mode are formed, so that only predistortion of only the target circuit is performed. In comparison, the distortion of the finally formed transmission output signal V (RF, PA) can be further suppressed.

  Further, a predistortion unit 103 that compensates and supplies the phase component signal S12 is provided before the phase modulation unit 104 that forms the high-frequency phase modulation signal S13 from the phase component signal S12, and the high-frequency power amplifier 107 performs phase amplitude synthesis. In the mode, the distortion generated by the phase amplitude synthesis by the high frequency power amplifier 107 is compensated by the predistortion unit 103, and in the mode in which the phase amplitude synthesis is performed by the variable gain amplifier 109, the phase amplitude by the variable gain amplifier 109 is compensated. By compensating for the distortion caused by the synthesis, it becomes possible to obtain the transmission output signal V (RF, PA) with much less distortion.

(Embodiment 2)
FIG. 5 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 includes an output measurement unit 204 that measures the output of the high-frequency power amplifier 107, an output measurement unit 205 that measures the output of the variable gain amplifier 109, and the configuration of the predistortion units 201, 202, and 203. The configuration is the same as that of the polar modulation transmission apparatus 100 of FIG.

  Each predistortion unit 201, 202, 203 has a measurement value of a detection output of the phase amplitude synthesized signal V (RF, PA) and variable gain amplifier output V (RF, VGA) measured by the output measurement units 204, 205, respectively. Is entered. In addition to the predistortion processing described in the first embodiment, each predistortion unit 201, 202, 203 performs adaptive predistortion processing so that distortion included in the measurement value is suppressed. As a result, even when the distortion characteristics change due to a temperature change or aging change of each circuit, the distortion can be suppressed by the predistortion units 201, 202, and 203.

  By the way, in the present embodiment, since the predistortion units 201 and 202 are provided as predistortion means for the amplitude component signal, distortion compensation for the amplitude component signal is shared by the predistortion units 201 and 202. Adaptive (complementary) distortion compensation can be performed.

  For example, in the mode in which the high-frequency power amplifier 107 performs phase amplitude synthesis, if only the predistortion unit 201 exists, the value of the gain control signal V (VGA) cannot be adaptively changed. Even when the output power-Vcc characteristic of FIG. 3 changes due to a change over time, the output distortion accompanying the change cannot be compensated. However, since the predistortion unit 202 is also present in the present embodiment, the selection of Pin in FIG. 3 can also be performed adaptively, and these two predistortion means can be combined appropriately to each predistortion means. Allocation can be optimally distributed and adaptive predistortion that is optimal as a whole can be performed.

  Further, in the present embodiment, not only the output measuring unit 204 of the high frequency power amplifier 107 but also the output measuring unit 205 that measures the output of the variable gain amplifier 109 is provided. It is possible to perform predistortion processing optimized for the temperature change and the secular change of each of the amplifier 107 and the variable gain amplifier 109.

  Next, the predistortion processing by the polar modulation transmission apparatus 200 of the present embodiment will be described in detail using FIG. Here, the processing from step ST10 to step ST15 is the same as the processing from step ST0 to step ST5 described in FIG.

  In step ST16, it is determined whether or not to update the table data of each predistortion unit 201, 202, 203 based on the measurement values from the output measurement units 204, 205. Specifically, if the distortion of the measured value is not less than a specified value, it is determined to update the table data, and the process proceeds to step ST17. If the distortion is not more than the specified value, step is performed. Return to ST11.

  In step ST17, each predistortion unit 201, 202, 203 changes the predistortion characteristics so that the distortion is converged to the smallest value while referring to the measurement values from the output measurement units 204, 205. Then, the table data is updated to the data when the distortion becomes the smallest in step ST18, and the process returns to step ST11. Incidentally, the processing from step ST16 to step ST18 may be performed by each predistortion unit 201, 202, 203, but the measured values of the output measurement units 204, 205 are taken into another control unit (not shown), You may make it perform by a control part.

  Thus, according to the present embodiment, in addition to the configuration of the first embodiment, the predistortion units 201, 202, and 203 correspond to the distortions actually measured at the outputs of the high frequency power amplifier 107 and the variable gain amplifier 109. By updating the predistortion process, in addition to the effects of the first embodiment, distortion can be suppressed even when there is a temperature change or a secular change.

  In this embodiment, the case where distortion due to temperature change is suppressed based on the outputs of the high-frequency power amplifier 107 and the variable gain amplifier 109 has been described. However, the present invention is not limited to this. For example, the predistortion units 201, 202, and 203 A table corresponding to the temperature may be provided, and the predistortion process may be performed by selecting a table corresponding to the temperature detected by the temperature sensor.

(Embodiment 3)
FIG. 7 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 300 has the same configuration as the polar modulation transmission apparatus 100 of FIG. 1 except that it includes delay adjustment units 301 and 302.

  By providing the delay adjustment units 301 and 302 in this way, the high-frequency power amplifier 107 or the variable gain amplifier 109 can be synchronized when the high-frequency phase modulation signal S13 and the amplitude control signal S22 are combined in phase and amplitude. Therefore, in addition to the suppression of distortion, it is possible to obtain a much better phase / amplitude synthesized signal with no synchronization shift during synthesis.

  In other words, in the polar modulation transmission apparatus, if the processing delay in the phase modulation unit 104 and the multiplier 102 is not absorbed, a synchronization shift occurs during phase amplitude synthesis and signal quality (for example, EVM (error vector magnitude)) is deteriorated. In the present embodiment, in consideration of this, by providing the delay adjustment units 301 and 302, the difference in transmission time until the phase amplitude synthesis of the path of the amplitude component signal and the path of the phase component signal is eliminated. Yes.

  Thus, according to the present embodiment, in addition to the effects of the first embodiment, the predistortion sections 105, 108, 103 and the like are provided by providing the delay adjustment sections 301 and 302 in addition to the configuration of the first embodiment. Since the delay difference can be absorbed, distortion during phase amplitude synthesis caused by this can be suppressed, and a phase / amplitude synthesized signal with higher quality can be obtained.

  The position where the delay adjusting unit is provided is not limited to the position shown in FIG. 7, but may be any position as long as the position can be synchronized when combining the amplitude component signal S11 and the amplitude control signal S22. As shown in FIG. 7, it may be provided only on one path instead of both paths.

(Embodiment 4)
FIG. 8, 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 this embodiment. Polar modulation transmission apparatus 400 inputs modulation scheme / band switching signal S40 to each predistortion unit 401, 402, 403. Each predistortion unit 401, 402, 403 has a table for each modulation scheme and band (transmission signal band) in addition to the predistortion processing described in the first embodiment, and a modulation scheme / band switching signal S40. Predistortion processing is performed by selecting a table corresponding to the above.

  This makes it possible to perform predistortion processing suitable for the modulation scheme and transmission signal band, so that even when the modulation scheme and transmission signal band are switched, good distortion compensation can be performed. Become.

  Incidentally, the modulation scheme indicates the modulation scheme of the baseband signal S10, and specifically indicates BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and the like. These modulations are performed by a modulation circuit provided on the upstream side of the amplitude / phase separation unit 101. The transmission signal band (band) is determined by the carrier frequency used in the phase modulation unit 104.

  Thus, according to the present embodiment, in addition to the configuration of the first embodiment, the predistortion process is changed in accordance with the modulation method and the band, so that, for example, the adaptation is applied in addition to the effect of the first embodiment. Even when the device is mounted on a device that performs a modulation method or a device that switches a transmission frequency band, distortion can be suppressed corresponding to each modulation method and band.

  In the first to fourth embodiments described above, the case where the predistortion unit is configured by a CPU (Central Processing Unit) and a lookup table and the predistortion process is performed based on the lookup table has been described. For example, an analog circuit or a digital circuit may be used.

  In the above-described embodiment, the case where the predistortion unit 105 performs envelope follow has been described. However, the above envelope follow includes envelope tracking.

  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. Flowchart for explaining predistortion processing according to the first embodiment The figure which serves for explanation of the look-up table provided in the predistortion section Waveform diagram showing the output waveform of each part of the first embodiment FIG. 3 is a block diagram illustrating a configuration of a polar modulation transmission apparatus according to a second embodiment. Flowchart for explaining predistortion processing according to the second embodiment Block diagram showing a configuration of a polar modulation transmission apparatus according to a third embodiment Block diagram showing a configuration of a polar modulation transmission apparatus according to a fourth embodiment Block diagram showing the configuration of a conventional polar modulation transmitter

Explanation of symbols

100, 200, 300, 400 Polar modulation transmission apparatus 101 Amplitude phase separation unit 102 Multiplier 103, 105, 108, 201, 202, 203, 401, 402, 403 Predistortion unit 104 Phase modulation unit 107 High frequency power amplifier 109 Variable gain Amplifiers 204 and 205 Output measurement unit 301 and 302 Delay adjustment unit S10 Baseband signal S11 Amplitude component signal S12 Phase component signal S13 High-frequency phase modulation signal S20 Average output power control signal S21 Operation mode switching signal S22 Amplitude control signal V (PA) Power supply Voltage V (VGA) gain control signal
V (RF, VGA) Variable gain amplifier output V (RF, PA) Phase amplitude composite signal

Claims (11)

A high frequency power amplifier for amplifying the high frequency phase modulation signal;
A variable gain amplifier provided on the front side of the high frequency power amplifier for amplifying the high frequency phase modulation signal;
A first predistortion unit for compensating a power supply voltage supplied to the high-frequency power amplifier;
A second predistortion unit for compensating a gain control signal supplied to the variable gain amplifier;
A first mode in which the high frequency phase modulation signal and the amplitude component signal are combined by the high frequency power amplifier, and a phase amplitude combination of the high frequency phase modulation signal and the amplitude component signal by the variable gain amplifier. Has a second mode to
The polar modulation transmission apparatus, wherein the first and second predistortion units form the power supply voltage and the gain control signal that complementarily compensate for distortion of the phase amplitude composite signal in each mode. During the first mode,
The first predistortion unit compensates the amplitude component signal in consideration of distortion characteristics of the high frequency power amplifier to form a power supply voltage to be supplied to the high frequency power amplifier, and the second predistortion unit The polar modulation transmission apparatus according to claim 1, wherein the gain control signal is supplied in consideration of linearity of phase / amplitude synthesis in the high-frequency power amplifier. During the second mode,
The first predistortion unit supplies a power supply voltage obtained by envelope-following the amplitude component signal, and the second predistortion unit compensates for the amplitude component signal in consideration of distortion characteristics of the variable gain amplifier. The polar modulation transmission apparatus according to claim 1, wherein a gain control signal supplied to the variable gain amplifier is formed. A third predistortion unit that compensates and supplies the phase component signal to the phase modulation unit that forms the high-frequency phase modulation signal from the phase component signal;
The third predistortion unit compensates for distortion characteristics generated by phase amplitude synthesis by the high-frequency power amplifier in the first mode, and occurs by phase amplitude synthesis by the variable gain amplifier in the second mode. The polar modulation transmission apparatus according to any one of claims 1 to 3, wherein distortion characteristics are compensated. The compensation process of the first and / or second predistortion unit is adjusted based on the output of the high-frequency power amplifier and / or the output of the variable gain amplifier. The polar modulation transmission device according to 1. The delay adjustment part which performs the synchronous adjustment at the time of the said phase amplitude synthesis | combination by delaying the said amplitude component signal and / or the said phase component signal is provided. The Claim 1 characterized by the above-mentioned. Polar modulation transmitter. 5. The polar according to claim 4, wherein compensation processing of the first, second, and / or third predistortion unit is adjusted based on an output of the high-frequency power amplifier and / or an output of the variable gain amplifier. Modulation transmitter. The polar modulation transmission apparatus according to claim 4, further comprising a delay adjustment unit that performs synchronization adjustment at the time of the phase amplitude synthesis by delaying the amplitude component signal and / or the phase component signal. The polar modulation transmission apparatus according to any one of claims 1 to 3, wherein the first and / or second predistortion units perform different compensation processes depending on a modulation scheme or a transmission frequency band. The polar modulation transmission apparatus according to claim 4, wherein the first, second, and / or third predistortion units perform different compensation processes according to a modulation scheme or a transmission frequency band. In the first mode, the high frequency power amplifier synthesizes the phase amplitude of the high frequency phase modulation signal and the amplitude component signal, and in the second mode, the high frequency power amplifier provides the high frequency by the variable gain amplifier provided on the front side of the high frequency power amplifier. A phase amplitude synthesis step of phase amplitude synthesis of the phase modulation signal and the amplitude component signal;
In the first mode, a power supply voltage supplied to the high-frequency power amplifier is formed by compensating for the amplitude component signal in consideration of the distortion characteristics of the high-frequency power amplifier, and the linearity of phase amplitude synthesis in the high-frequency power amplifier. Providing a gain control signal to the variable gain amplifier so that the characteristics are maintained;
In the second mode, a power supply voltage obtained by envelope-following the amplitude component signal is supplied to the high frequency power amplifier, and gain control formed by compensating the amplitude component signal in consideration of distortion characteristics of the variable gain amplifier Providing a signal to the variable gain amplifier.

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