JP4714184B2 - Wireless signal amplifier - Google Patents

Description

  The present invention relates to a radio signal amplifying device, and more particularly to a radio signal amplifying device having a multistage amplifier configuration.

  2. Description of the Related Art Conventionally, as a wireless signal amplifying apparatus for a mobile terminal or a base station thereof, there has been one in which a plurality of amplifiers are cascade-connected to obtain a desired transmission power (for example, see Patent Document 1).

  FIG. 6 shows a configuration example of the radio signal amplifying device when the supply voltage to the power amplifier and the supply voltage to the driver amplifier are different. In the radio signal amplifying apparatus 10 (hereinafter, simply referred to as the amplifying apparatus 10) of FIG. 6, a driver amplifier 11 is cascade-connected to the previous stage of the power amplifier 12, and the radio signal (RF signal) is transmitted to the driver amplifier 11 and the power amplifier 12 as shown in FIG. After being amplified by the above, the antenna AN is supplied. The driver amplifier 11 and the power amplifier 12 generally have a drain control type or collector control type amplifier configuration.

  The amplifying apparatus 10 supplies a system voltage supplied from a battery or the like as a power supply voltage for the driver amplifier 11 via the DC / DC converter 13 and a power supply voltage for the power amplifier 12 via the DC / DC converter 14. Supply as. By providing the DC / DC converters 13 and 14 in this way, the noise (variation) component of the system voltage is removed, and a constant voltage without noise variation is supplied to the driver amplifier 11 and the power amplifier 12. Thereby, amplification operation can be stabilized.

  Further, in recent years, as a technique for operating the power amplifier at the final stage with high efficiency, what is called an ET (envelope tracking) method, an EER (envelope elimination and restoration) method, or a polar modulation method has been attracting attention (hereinafter, referred to as “the ET”) These methods are referred to as drain modulation methods).

  In the drain modulation method, as shown in FIG. 7, the transmission signal is divided into an RF component and an envelope (amplitude component), and the RF signal converted into the radio band is input to the power amplifier 21 and the envelope component is converted into the power supply modulation unit 22. To the power supply terminal of the power amplifier 21.

  The power supply modulation unit 22 modulates the system voltage according to the envelope component. This process corresponds to amplifying the envelope component to form the power supply voltage of the power amplifier 21. In the drain modulation method, by operating the power amplifier 21 in a saturated state, it is possible to obtain an output signal in which the RF signal and the envelope component are combined while operating the power amplifier 21 with high efficiency.

  FIG. 8 and FIG. 9 show configuration examples in the case where an amplifying device having a multistage amplifier configuration is applied to a drain modulation type transmitter.

  8 amplifies the power supply voltage of the power amplifier 32 by modulating the system voltage by the power supply modulation unit 33 according to the envelope component. Further, the amplifying device removes the noise fluctuation of the system voltage by the DC / DC converter 34 to form the power supply voltage of the driver amplifier 31. As a result, the power amplifier 32 is supplied with a power supply voltage that varies in the range of, for example, 10 to 50 [V] according to the envelope component, and the driver amplifier 31 is supplied with a fixed power supply voltage of, for example, 50 [V]. . Here, since the noise included in the system voltage is absorbed during modulation by the power supply modulation unit 33, no noise fluctuation of the system voltage appears in the output of the power supply modulation unit 33.

In the amplifying apparatus shown in FIG. 9, in which parts corresponding to those in FIG. Is also used. As a result, there is no need to provide a DC / DC converter exclusively for the driver amplifier, and the configuration can be simplified accordingly. Incidentally, both the driver amplifier 31 and the power amplifier 32 are supplied with a power supply voltage that fluctuates in a range of, for example, 10 to 50 [V] according to the envelope component.
JP 2005-518684 A

  As described above, the driver amplifier and the power amplifier generally have a drain control type or collector control type amplifier configuration. In general, the drain control type or collector control type amplifier does not have a constant output-to-gain characteristic (AM-AM characteristic).

  When the configuration as shown in FIG. 9 is adopted, the AM-AM characteristic of the output amplitude with respect to the original signal of the power amplifier 32 which is the final stage amplifier has a smaller gain as the output becomes smaller as shown by the solid line in FIG. . In order to make the output amplitude of the power amplifier 32 linear, the gain of the AM-AM characteristic with respect to the original signal amplitude of the output amplitude of the driver amplifier 31 increases as the output decreases as shown by the dotted line in FIG. .

  Therefore, since the PAPR (Peak to Average Power Ratio) of the output voltage waveform of the driver amplifier 31 and the output voltage waveform of the power amplifier 32 is different, when the same power supply voltage V1 is supplied to the driver amplifier 31 and the power amplifier 32, the driver amplifier 31 May become inoperable.

  This will be described with reference to FIG. 11A shows the relationship between the output voltage waveform V3 to be output from the driver amplifier 31 and the power supply voltage V1, and FIG. 11B shows the relationship between the output voltage waveform V4 to be output from the power amplifier 32 and the power supply voltage V1. As can be seen from FIG. 11A, during the period from time t1 to time t2, the output voltage V3 to be output from the driver amplifier 31 becomes higher than the power supply voltage V1, and the driver amplifier 31 becomes inoperable during this period.

  In this way, if the configuration shown in FIG. 9 is adopted, it is not necessary to provide a DC / DC converter exclusively for the driver amplifier, so that the configuration can be simplified correspondingly, but a desired voltage cannot be output from the driver amplifier 31. There is a fear. As a result, the quality of the output voltage waveform (transmission signal) V4 from the power amplifier 32 finally obtained may be deteriorated.

  The present invention has been made in view of the above points, and provides a radio signal amplifier capable of obtaining a desired transmission signal waveform even when the power supply system is simplified when a multistage amplifier configuration is adopted. .

  One aspect of the wireless signal amplifying device according to the present invention includes a first amplifying unit, a second amplifying unit connected to a front stage of the first amplifying unit, a system voltage modulated, and the first amplifying unit. A power supply modulating means for forming the power supply voltage of the amplifying means; and a smoothing means for smoothing the power supply voltage formed by the power supply modulating means to form the power supply voltage of the second amplifying means. Take.

  According to this configuration, since the low level portion of the power supply voltage formed in the power supply modulation means is raised by the smoothing means, the second amplification means is always smoothed with a value larger than the output voltage of the second amplification means. A voltage can be supplied. Thereby, it can be avoided that the second amplification means becomes inoperable.

  One aspect of the wireless signal amplifying device of the present invention is formed by a first amplifying unit, a power source modulating unit that modulates a system voltage to form a power source voltage of the first amplifying unit, and the power source modulating unit. Limiter means for limiting the power supply voltage to a voltage equal to or higher than a predetermined value; and second amplification means connected to the front side of the first amplification means and using the voltage restricted by the limiter means as the power supply voltage. The structure to comprise is taken.

  According to this configuration, the limiter unit can always supply a limiter voltage having a value larger than the output voltage of the second amplification unit to the second amplification unit. Thereby, it can be avoided that the second amplification means becomes inoperable.

  ADVANTAGE OF THE INVENTION According to this invention, when a multistage amplifier structure is employ | adopted, even if it simplifies a power supply system, the radio | wireless signal amplifier which can obtain a desired transmission signal waveform is realizable.

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

(Embodiment 1)
FIG. 1 shows a configuration of transmitting apparatus 200 using radio signal amplifying apparatus 100 according to Embodiment 1 of the present invention. The transmission apparatus 200 transmits a transmission signal by a method called an ET method, an EER method, or a polar modulation method, and is provided in a radio base station, for example.

  The transmission device 200 includes a wireless signal amplification device 100. Radio signal amplifying apparatus 100 detects the envelope signal of the original signal by envelope signal detector 110 and sends the detected envelope signal to power supply modulator 103.

  Further, the radio signal amplifying apparatus 100 performs predistortion processing by a digital predistortion unit (DPD) 105, frequency-converts the signal after predistortion processing to a radio frequency by a frequency conversion unit 111, and converts the obtained RF signal into a driver Input to the amplifier 101. A power amplifier 102 is connected to the rear stage side of the driver amplifier 101, and an antenna AN is connected to the output side of the power amplifier 102. Thus, the RF signal is amplified by the driver amplifier 101 and the power amplifier 102 and then transmitted from the antenna AN. Here, the driver amplifier 101 and the power amplifier 102 are drain control type or collector control type amplifiers.

  The power supply modulation unit 103 modulates the system voltage according to the envelope signal, thereby forming a power supply voltage V10 corresponding to the envelope waveform. The power supply voltage V <b> 10 is supplied as a power supply voltage for the power amplifier 102. Here, the noise fluctuation included in the system voltage is absorbed by the modulation in the power supply modulation unit 103.

  In addition to this configuration, the radio signal amplifying device 100 includes a smoothing unit 104 between the power supply modulation unit 103 and the power supply terminal of the driver amplifier 101, and smoothes (integrates) the power supply voltage V10 by the smoothing unit 104. After that, the power supply voltage of the driver amplifier 101 is supplied.

  Thereby, in the radio signal amplifying apparatus 100, the smoothed voltage V11 having a voltage value always higher than the output voltage V13 to be output from the driver amplifier 101 is obtained, and the driver amplifier 101 is operated by the smoothed voltage V11. Therefore, it can be avoided that the driver amplifier 101 becomes inoperable. Incidentally, the driver amplifier 101 is configured to be operable at a lower voltage than the power amplifier 102 (for example, configured by GaAs or the like).

  FIG. 2 shows the relationship between the power supply voltage V10 output from the power supply modulation unit 103, the smoothed voltage V11, and the output voltage V13 to be output from the driver amplifier 101. FIG. 2 shows an example in which the fluctuation range of the power supply voltage V10 is 10 to 50 [V]. As can be seen from the figure, when the power supply voltage V10 is directly supplied to the driver amplifier 101, there are places where the power supply voltage V10 becomes smaller than the output voltage V13. However, if the configuration of the present embodiment is used, the smoothing unit 104 supplies the power supply voltage V10. The low level portion of the voltage V10 is raised, and the driver amplifier 101 can be supplied with the smoothed voltage V11 that is always larger than the output voltage V13. As a result, the driver amplifier 101 can always output the desired output voltage V13 without disabling the driver amplifier 101.

  FIG. 3 shows a specific configuration example of the smoothing unit 104. 3 includes an isolator 106 and a capacitor 107 having a large capacity. The smoothing unit 104 obtains the smoothed voltage V11 by the integration function of the capacitor 107 while ensuring the isolation between the power line of the power amplifier 102 and the power line of the driver amplifier 101 by the isolator 106.

  As described above, according to the present embodiment, the power supply voltage V10 formed by the power supply modulation unit 103 is supplied to the power amplifier 102, and the power supply voltage V10 formed by the power supply modulation unit 103 is substantially constant by the smoothing unit 104. By smoothing the voltage and supplying it to the driver amplifier 101, the driver amplifier 101 is prevented from becoming inoperable even when the power supply voltage formed by the power supply modulation unit 103 is shared by the power amplifier 102 and the driver amplifier 101. Thus, a desired output voltage waveform (transmission signal) can be obtained from the power amplifier 102. As a result, when the multistage amplifier configuration is adopted, the radio signal amplifying apparatus 100 that can obtain a desired transmission signal waveform even if the power supply system is simplified can be realized.

  Note that since the radio signal amplifying apparatus 100 includes the digital predistortion unit 105, the influence of smoothing the power supply voltage of the driver amplifier 101 by the smoothing unit 104 can be easily compensated by the predistortion process. it can. Here, since the predistortion process is a process generally used in the ET system, the EER system, or the polar modulation system, it can be said that the present embodiment effectively uses this process.

(Embodiment 2)
FIG. 4, in which the same reference numerals are assigned to the parts corresponding to those in FIG. 3, shows the configuration of the radio signal amplifying apparatus of the second embodiment.

  The radio signal amplifying apparatus 100 according to the present embodiment is provided with a limiter 301 instead of the smoothing unit 104. The limiter 301 is formed by the power supply modulation unit 103 and limits the power supply voltage V10 to a voltage equal to or higher than a predetermined value. In the case of the present embodiment, as shown in FIG. 5, the limiter 301 limits the power supply voltage V10, which fluctuates in the range of 10 to 50 [V], to the lower limit value of 10 [V], and this is the driver. Output as power supply voltage V20 of the amplifier 302.

  As shown in FIG. 5, the driver amplifier 302 according to the present embodiment is configured such that the maximum output voltage of the output voltage V <b> 21 is equal to or lower than the power supply voltage V <b> 20 supplied from the limiter 301. Thus, even when the power supply voltage V10 formed by the power supply modulation unit 103 is used in common by the power amplifier 102 and the driver amplifier 302, it is possible to prevent the driver amplifier 302 from becoming inoperable. A voltage waveform (transmission signal) can be obtained.

  In the present embodiment, the case where the limiter 301 is limited to the fixed voltage of the power supply voltage 10 [V] from the power supply modulation unit 103 has been described. However, the present invention is not limited to this, and the limiter 301 includes a driver amplifier. What is necessary is just to restrict | limit the minimum voltage value of the power supply voltage V20 supplied to 302 so that it may become the value more than the maximum output voltage of the driver amplifier 302. FIG.

  The radio signal amplifying device of the present invention has an effect that a desired transmission signal waveform can be obtained even if the power supply system is simplified when a multistage amplifier configuration is adopted. For example, the ET method, EER method, or polar It is suitable to be applied to a modulation type radio transmission apparatus.

FIG. 1 is a block diagram showing a configuration of a transmission apparatus and a radio signal amplification apparatus according to Embodiment 1 of the present invention. The figure which shows the relationship between the power supply voltage V10 output from a power supply modulation | alteration part, the smoothing voltage V11, and the output voltage V13 which should be output from driver amplifier. Block diagram showing a configuration example of the smoothing unit FIG. 3 is a block diagram illustrating a configuration of a radio signal amplifying device according to a second embodiment. The figure which shows the relationship between the power supply voltage V10 output from a power supply modulation | alteration part, the limiter voltage V20, and the output voltage V21 from driver amplifier. Connection diagram showing a configuration example of a conventional radio signal amplifying apparatus having a multistage amplifier configuration Connection diagram for explaining drain modulation system The figure which shows the example of the conventional structure at the time of applying the radio signal amplifier of a multistage amplifier structure to a drain modulation system The figure which shows the example of the conventional structure at the time of applying the radio signal amplifier of a multistage amplifier structure to a drain modulation system The figure which shows the AM-AM characteristic of the driver amplifier and power amplifier which were connected in cascade 11A shows the relationship between the output voltage waveform V3 to be output from the driver amplifier and the power supply voltage V1, and FIG. 11B shows the relationship between the output voltage waveform V4 to be output from the power amplifier and the power supply voltage V1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Radio signal amplifier 101,302 Driver amplifier 102 Power amplifier 103 Power supply modulation part 104 Smoothing part 105 Digital predistortion part (DPD)
301 limiter

Claims (7)

First amplification means;
A second amplifying means connected to the front side of the first amplifying means;
Power modulation means for modulating a system voltage to form a power supply voltage for the first amplification means;
Smoothing means for smoothing the power supply voltage formed by the power supply modulating means to form the power supply voltage of the second amplifying means;
A wireless signal amplifying apparatus comprising: The radio signal amplifier according to claim 1, wherein the second amplifying unit is configured to be operable with a power supply voltage lower than that of the first amplifying unit. First amplification means;
Power modulation means for modulating a system voltage to form a power supply voltage for the first amplification means;
Limiter means for limiting the power supply voltage to a voltage equal to or higher than a predetermined value formed by the power supply modulation means;
A second amplifying means connected to the front side of the first amplifying means and having a voltage limited by the limiter means as a power supply voltage;
A wireless signal amplifying apparatus comprising: The radio signal amplifying apparatus according to claim 3, wherein the predetermined value limited by the limiter means is a value equal to or greater than a maximum output voltage of the second amplifying means. Predistortion means for predistorting a signal input to the second amplification means based on the output voltage of the first amplification means;
The radio signal amplifying device according to any one of claims 1 to 4. The radio signal amplifier according to any one of claims 1 to 5, wherein the first and second amplifying units are drain control type or collector control type amplifiers. The radio signal amplifying device according to any one of claims 1 to 6 is used for a radio transmission device of an ET scheme, an EER scheme, or a polar modulation scheme,
The second amplification means inputs an RF phase signal,
The power supply modulation means inputs an envelope signal and modulates the system voltage based on the envelope signal.

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