WO2014061333A1 - Transmission amplifier - Google Patents

Transmission amplifier Download PDF

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Publication number
WO2014061333A1
WO2014061333A1 PCT/JP2013/071112 JP2013071112W WO2014061333A1 WO 2014061333 A1 WO2014061333 A1 WO 2014061333A1 JP 2013071112 W JP2013071112 W JP 2013071112W WO 2014061333 A1 WO2014061333 A1 WO 2014061333A1
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Prior art keywords
output
amplifier
switch mode
switch
transmission line
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PCT/JP2013/071112
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French (fr)
Japanese (ja)
Inventor
一実 椎熊
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日本電気株式会社
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Priority to JP2014541978A priority Critical patent/JPWO2014061333A1/en
Publication of WO2014061333A1 publication Critical patent/WO2014061333A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H03F3/217—Class D power amplifiers; Switching amplifiers
    • H03F3/2178—Class D power amplifiers; Switching amplifiers using more than one switch or switching amplifier in parallel or in series
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/60—Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators
    • H03F3/602—Combinations of several amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/537—A transformer being used as coupling element between two amplifying stages

Definitions

  • the present invention relates to a technique for synthesizing output signals of a plurality of switch mode amplifiers, and more particularly to a technique for synthesizing a radio frequency multi-bit digital signal after amplification.
  • the base station of the wireless communication system transmits a signal having a large difference between the average power and the peak power.
  • a digital transmitter that converts a transmission signal into a digital transmission signal of a radio frequency and amplifies it has been studied.
  • a switch mode amplifier such as a class D amplifier or a class S amplifier has been studied.
  • the switch mode amplifier assumes a pulse waveform signal as an input signal and amplifies power while maintaining the pulse waveform.
  • the pulse waveform signal amplified by the switch mode amplifier is output from the digital transmitter after removing frequency components other than the band of the desired radio signal.
  • a plurality of switch mode amplifiers corresponding to a plurality of bits of the digital transmission signal are provided, and output signals of the plurality of switch mode amplifiers are combined and supplied to a load (antenna). .
  • Non-Patent Document 1 describes a technique for synthesizing the output signals of a plurality of amplifiers via quarter wavelength transmission lines having different characteristic impedances. Has been.
  • Non-Patent Document 1 is a configuration using a quarter wavelength transmission line, it is assumed that the transmission amplifier is operated near a certain frequency determined by the quarter wavelength transmission line. Will be limited by the frequency band.
  • Non-Patent Document 1 has a problem that it is difficult to increase the bandwidth because the frequency band is limited as described above.
  • an object of the present invention is to provide a transmission amplifier that can solve the above-described problems and can operate in a wide band.
  • the transmission amplifier of the present invention includes: A plurality of switch mode amplifiers provided corresponding to each of the plurality of bits of the radio frequency digital signal; A plurality of signal path portions provided in the subsequent stage of each of the plurality of switch mode amplifiers, The plurality of signal path portions are: The output stages are connected in series with each other and connected in parallel with the load, Each of the plurality of signal path portions is A transmission line transformer provided at a subsequent stage of the switch mode amplifier, one end of the first line is connected to the switch mode amplifier, and one end of the second line is grounded; An output switch element provided at a subsequent stage of the transmission line transformer and connected between the other end of the first line and the other end of the second line of the transmission line transformer; The output switch element is When the power supply voltage is output from the switch mode amplifier, the switch is opened. When the power supply voltage is not output, the switch mode amplifier is closed.
  • FIG. 2 is a circuit diagram showing an example of a connection relationship between a switch mode amplifier and a transmission line transformer shown in FIGS. 1A to 1D.
  • FIG. 7 is a circuit diagram showing another example of the connection relationship between the switch mode amplifier and the transmission line transformer shown in FIGS. 1A to 1D.
  • 1A to 1D show the circuit configuration of the transmission amplifier of the present embodiment.
  • the transmission amplifier of this embodiment includes switch mode amplifiers 10-1 and 10-2, transmission line transformers 20-1 and 20-2, and a switch element (output switch element) 30. -1,30-2.
  • the transmission line transformer 20-1 and the switch element 30-1 constitute a first signal path section.
  • the transmission line transformer 20-2 and the switch element 30-2 constitute a second signal path section.
  • these two signal path units are connected in series to each other in the output stage, and are connected in parallel to the load (antenna) 40.
  • the switch mode amplifier 10-1 is provided corresponding to one bit of the 2-bit digital transmission signal.
  • the transmission line transformer 20-1 is provided in the subsequent stage of the switch mode amplifier 10-1, and is composed of two lines. These two lines can be realized by windings as shown in FIGS. 1A to 1D or microstrip lines.
  • FIG. 1A to 1D show the switch mode amplifier 10-1 in a simplified manner, and the specific connection relationship between the switch mode amplifier 10-1 and the transmission line transformer 20-1 is shown in FIG. 2 or FIG. become that way.
  • the switch mode amplifier 10-1 includes switch elements (input switch elements) 11 and 12 on the high side (power supply side) and the low side (ground side), respectively.
  • the elements 11 and 12 are connected in series with each other. Only one of the switch elements 11 and 12 is controlled to be in a closed state. When the switch element 11 is in a closed state, the power supply voltage V1 is output. When the switch element 11 is open, the switch element 12 is closed and a ground voltage is output.
  • one end of one line (hereinafter referred to as a first line) of the transmission line transformer 20-1 is connected to a connection point of the switch elements 11 and 12, and the other line (hereinafter referred to as a second line).
  • One end of the track is called ground.
  • the switch mode amplifier 10-1 is configured to include the switch element 11 only on the high side (power supply side). When the switch element 11 is closed, the power supply voltage V1 is output.
  • one end of the first line of the transmission line transformer 20-1 is connected to the switch element 11, and one end of the second line is grounded.
  • the switch element 30-1 is provided in the subsequent stage of the transmission line transformer 20-1, and is connected between the other end of the first line and the other end of the second line of the transmission line transformer 20-1.
  • the switch element 30-1 performs the following switching operation in accordance with the output voltage of the switch mode amplifier 10-1.
  • the switch element 11 of the switch mode amplifier 10-1 when the switch element 11 of the switch mode amplifier 10-1 is in the closed state (Short) and the power supply voltage V1 is output, the switch element 30-1 is in the open state (Open) (FIG. 1A, FIG. 1B).
  • the switch element 11 of the switch mode amplifier 10-1 is in the open state (Open) and the power supply voltage V1 is not output, the switch element 30-1 is in the closed state (Short) (FIG. 1C, FIG. 1D).
  • the switching operation of the switch element 30-1 is performed in synchronization with the output of the switch mode amplifier 10-1, and it is necessary to correct the timing by the amount of delay in the transmission line transformer 20-1.
  • a separate control unit (not shown) may be provided, and the control unit may control the switching element 30-1 to perform the above switching operation.
  • the control unit may control the switching element 30-1 to perform the above switching operation.
  • the switch element 30-1 is formed of a diode as in an embodiment described later, the transmission line transformer can be synchronized with the output of the switch mode amplifier 10-1 without providing the control unit. Since the switching operation is performed at a timing delayed by the delay of 20-1, the above control unit is not necessary.
  • the switch element 12 since the switch element 12 is provided on the low side (ground side), a desired voltage can be output even if the switch element 30-1 is not provided. There is no need to provide a separate control unit (not shown). However, in order to operate at a higher frequency, it is desirable to provide the switch element 30-1 because the delay generated in the transmission line transformer 20-1 can be suppressed particularly when the ground voltage is output. .
  • the switch element 30-1 can be constituted by, for example, an electronic switch in addition to the diode, but in this case, the above-described control unit needs to be provided.
  • the characteristic impedance of the transmission line transformer 20-1 can be arbitrarily set.
  • the characteristic impedance of the load 40 is 50 ⁇
  • it may be set to 50 ⁇ so as to be matched with this.
  • the characteristic impedance of the transmission line transformer 20-2 is also set to 50 ⁇ ).
  • the configuration on the switch mode amplifier 10-2 side is the same as the configuration on the switch mode amplifier 10-1 side, and the description thereof is omitted.
  • the power supply voltages V1 and V2 are output to the load 40 via the transmission line transformers 20-1 and 20-2.
  • the power supply voltage V1 is output to the load 40 side via the switch element 30-1, but the power supply voltage V2 is not output to the load 40 side. Further, no common mode current flows on the switch mode amplifier 10-2 side as viewed from the switch element 30-2.
  • the power supply voltage V2 is output to the load 40 side via the switch element 30-2, but the power supply voltage V1 is not output to the load 40 side. Further, the common mode current does not flow to the switch mode amplifier 10-1 side when viewed from the switch element 30-1.
  • the voltage at the load 40 is V2.
  • Power supply voltages V1 and V2 are not output. As shown in FIG. 1D, the switch elements 11 of the switch mode amplifiers 10-1 and 10-2 are both open (Open), and both power supply voltages V1 and V2 are output. If not, the switch elements 30-1 and 30-2 are both closed (Short).
  • the power supply voltages V1 and V2 are not output to the load 40 side.
  • a voltage obtained by combining the output voltages of the switch mode amplifiers 10-1 and 10-2 appears on the load 40 side. Therefore, a multi-bit digital transmission signal can be synthesized at a radio frequency.
  • the switch mode amplifier 10-1 shown in FIG. 2 when the switch mode amplifier 10-1 shown in FIG. 2 is applied, when the switch element 12 on the low side (ground side) is in the closed state, the switch element 30-1 is in the closed state (Short). As a result, the output terminal of the transmission line transformer 20-1 is also grounded.
  • the switch mode amplifier 10-1 shown in FIG. 3 when the switch element 12 on the high side (power supply side) is in the open state, the switch element 30-1 is in the closed state (Short). As a result, since the output terminal of the transmission line transformer 20-1 is also grounded, a low-side (ground-side) switching element is not necessary. Therefore, the configuration of the switch mode amplifier 10-1 can be simplified and the cost can be reduced (the same applies to the switch mode amplifier 10-2).
  • Example 1 4A to 4D show circuit configurations of the transmission amplifier of this embodiment.
  • the switch elements 30-1 and 30-2 shown in FIGS. 1A to 1D are realized by diodes 31-1 and 31-2, respectively.
  • the diode 31-1 is provided at the subsequent stage of the transmission line transformer 20-1, a cathode element is connected to the other end of the first line of the transmission line transformer 20-1, and an anode element is connected to the other end of the second line. It is connected.
  • the diode 31-1 is in a state where a reverse voltage is applied. Does not flow, and substantially becomes an open state (see FIGS. 4A and 4B).
  • the switch element 11 of the switch mode amplifier 10-1 when the switch element 11 of the switch mode amplifier 10-1 is in an open state (Open) and the power supply voltage V1 is not output, the diode 31-1 is in a state in which a forward voltage is applied. A current flows in a direction (a direction from the second line side toward the first line side), and a substantially closed state (Short) is obtained (see FIGS. 4C and 4D).
  • the configuration on the switch mode amplifier 10-2 side is the same as the configuration on the switch mode amplifier 10-1 side, and the description thereof is omitted.
  • the power supply voltages V1 and V2 are output to the load 40 via the transmission line transformers 20-1 and 20-2.
  • the power supply voltage V1 is output to the load 40 side via the diode 31-1, but the power supply voltage V2 is not output to the load 40 side. Further, no common mode current flows to the switch mode amplifier 10-2 side as viewed from the diode 31-2. In addition, the diode 31-2 has a voltage drop corresponding to the forward voltage Vf.
  • the power supply voltage V2 is output to the load 40 side via the diode 31-2, but the power supply voltage V1 is not output to the load 40 side. Further, no common mode current flows on the switch mode amplifier 10-1 side as viewed from the diode 31-1. In the diode 31-1, a voltage drop corresponding to the forward voltage Vf occurs.
  • the power supply voltages V1 and V2 are not output to the load 40 side.
  • a multi-bit digital transmission signal can be synthesized at a radio frequency.
  • Example 2 The present embodiment is an example in which the first signal path section and the second signal path section constituting the transmission amplifier according to the first embodiment are realized by a transmission line transformer having a double coaxial structure.
  • FIG. 5 shows the circuit configuration of the transmission amplifier of this embodiment.
  • the circuit configuration of the transmission amplifier of this embodiment is the same as that of the first embodiment.
  • FIG. 6 shows an external configuration of a transmission line transformer 50 having a double coaxial structure used in the transmission amplifier of this embodiment.
  • T1 to T7 correspond to the positions of T1 to T7 in FIG.
  • a center conductor 51, an inner conductor 52, and an outer conductor 53 are formed in this order from the center toward the outside. Further, a dielectric 54 (dielectric constant: ⁇ 1) is filled between the center conductor 51 and the inner conductor 52, and a dielectric 55 (dielectric constant: ⁇ 2) is filled between the inner conductor 52 and the outer conductor 53. Yes.
  • the outside of the transmission line transformer 50 having a double coaxial structure is surrounded by a ferrite sleeve (not shown) in order to increase the input / output isolation of the transmission line transformer and to remove the common mode current over a wide frequency band. It is desirable that
  • the polarity of the power supply voltage V2 of the switch mode amplifier 10-2 is applied opposite to that in FIG. 5 (that is, the polarity of the power supply voltage V2 is reversed in FIG. And an image applied to a circuit configuration in which the position T3 is grounded).
  • the characteristic impedance of the transmission line transformers 20-1 and 20-2 can be set by changing the dielectric constants ⁇ 1 and ⁇ 2 of the dielectrics 54 and 55 and the radius of the coaxial line.
  • the center conductor 51 is connected to the switch mode amplifier 10-1 (position T1), and the inner conductor 52 is grounded (positions T2 and T3).
  • the outer conductor 53 is connected to the switch mode amplifier 10-2 (position T4).
  • the center conductor 51 is connected to the load 40 (position T5), and the inner conductor 52 is not grounded (Open). (Position T6).
  • the current flowing through the dielectric 54 from one end of the transmission line transformer 50 toward the other end is folded back via the inner conductor 52 at the other end of the transmission line transformer 50 and flows into the dielectric 55. Therefore, the portion at position T6 is in a conductive state.
  • the outer conductor 53 is RF-grounded via a capacitor (position T7).
  • the reason why the outer conductor 53 is grounded instead of being grounded is to prevent the power source of the switch mode amplifier 10-2 from being grounded in a DC manner.
  • the first signal path portion and the second signal path portion are realized by a transmission line transformer having a double coaxial structure. Weight reduction can be achieved. Other effects are the same as those of the first embodiment.
  • the digital transmission signal is 2 bits.
  • the present invention is not limited to this, and can accommodate a multi-bit digital transmission signal.

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Abstract

This transmission amplifier has: a plurality of switch-mode amplifiers provided corresponding to a plurality of respective bits of a radio-frequency digital signal; and a plurality of signal channel units provided at the next-stages of the respective switch-mode amplifiers. The output stages of the signal channel units are connected in series with each other and connected in parallel with a load. Each of the signal channel units is provided at the next-stage of each of the switch-mode amplifiers and has: a transmission line transformer having a first line, one end of which is connected to one of the switch-mode amplifiers and a second line, one end of which is grounded; and an output switch element provided at the next-stage of the transmission line transformer and connected between the other end of the first line of the transmission line transformer and the other end of the second line of the transmission line transformer. The output switch element is brought into the open state when a power supply voltage is output from the one of the switch-mode amplifiers and into the close state when the power supply voltage is not output.

Description

送信増幅器Transmit amplifier
　本発明は、複数のスイッチモード増幅器の出力信号を合成する技術に関し、特に、無線周波数の多ビットデジタル信号を増幅後に合成する技術に関する。 The present invention relates to a technique for synthesizing output signals of a plurality of switch mode amplifiers, and more particularly to a technique for synthesizing a radio frequency multi-bit digital signal after amplification.
　無線通信システムの基地局は、平均電力とピーク電力との差分が大きな信号を送信する。近年、このような基地局等の送信機に用いられる送信増幅器の高効率化を図る技術として、送信信号を無線周波数のデジタル送信信号に変換して増幅するデジタル送信機が検討され、送信増幅器に用いられる増幅器として例えばＤ級増幅器やＳ級増幅器のようなスイッチモード増幅器が検討されている。スイッチモード増幅器は、入力信号としてパルス波形信号を想定し、そのパルス波形を維持したまま電力増幅する。スイッチモード増幅器で増幅されたパルス波形信号は、所望の無線信号の帯域以外の周波数成分が除去された後にデジタル送信機から出力される。 The base station of the wireless communication system transmits a signal having a large difference between the average power and the peak power. In recent years, as a technique for improving the efficiency of a transmission amplifier used in a transmitter of such a base station or the like, a digital transmitter that converts a transmission signal into a digital transmission signal of a radio frequency and amplifies it has been studied. As an amplifier to be used, a switch mode amplifier such as a class D amplifier or a class S amplifier has been studied. The switch mode amplifier assumes a pulse waveform signal as an input signal and amplifies power while maintaining the pulse waveform. The pulse waveform signal amplified by the switch mode amplifier is output from the digital transmitter after removing frequency components other than the band of the desired radio signal.
　また、送信信号の純度・品質をより高めるためには、デジタル送信信号の多ビット化が必要である。 Also, in order to further increase the purity and quality of the transmission signal, it is necessary to increase the number of bits of the digital transmission signal.
　それに対応する手段として、例えばデジタル送信信号の複数のビットにそれぞれ対応して複数のスイッチモード増幅器を設け、複数のスイッチモード増幅器の出力信号を合成して負荷（アンテナ）に供給する手段が考えられる。 As a means corresponding to this, for example, a plurality of switch mode amplifiers corresponding to a plurality of bits of the digital transmission signal are provided, and output signals of the plurality of switch mode amplifiers are combined and supplied to a load (antenna). .
　ここで、複数の増幅器の出力信号を合成する技術として、例えば、非特許文献１には、複数の増幅器の出力信号を、特性インピーダンスの異なる１／４波長伝送線路を介して合成する技術が記載されている。 Here, as a technique for synthesizing the output signals of a plurality of amplifiers, for example, Non-Patent Document 1 describes a technique for synthesizing the output signals of a plurality of amplifiers via quarter wavelength transmission lines having different characteristic impedances. Has been.
　しかし、非特許文献１に記載の技術は、１／４波長伝送線路を用いる構成であるため、送信増幅器を、１／４波長伝送線路によって決まるある周波数近傍で動作させることを前提としており、使用する周波数帯域の制限を受けてしまう。 However, since the technique described in Non-Patent Document 1 is a configuration using a quarter wavelength transmission line, it is assumed that the transmission amplifier is operated near a certain frequency determined by the quarter wavelength transmission line. Will be limited by the frequency band.
　その一方、近年、携帯電話や無線ＬＡＮ等の無線機器の爆発的な普及と高速・大容量通信回線を要求するコンテンツの増大を背景に、無線通信システムに割り当てられる周波数帯域幅や周波数帯域は増加してきている。そのような状況に迅速に対応するためには、送信増幅器としては複数の周波数帯の信号を増幅したり、信号を広帯域に増幅したりする性能が要求されており、この要求を満たすには、送信増幅器の広帯域化を図る必要がある。 On the other hand, in recent years, the frequency bandwidth and frequency band allocated to wireless communication systems have increased against the background of the explosive spread of wireless devices such as mobile phones and wireless LANs and the increase in content that requires high-speed and large-capacity communication lines. Have been doing. In order to respond quickly to such a situation, a transmission amplifier is required to have the ability to amplify signals in a plurality of frequency bands or amplify signals in a wide band. It is necessary to increase the bandwidth of the transmission amplifier.
　しかし、非特許文献１に記載の技術は、上述のように、周波数帯域が制限されるため、広帯域化を図ることが困難であるという課題がある。 However, the technique described in Non-Patent Document 1 has a problem that it is difficult to increase the bandwidth because the frequency band is limited as described above.
　そこで、本発明の目的は、上述した課題を解決し、広帯域に動作することができる送信増幅器を提供することにある。 Therefore, an object of the present invention is to provide a transmission amplifier that can solve the above-described problems and can operate in a wide band.
　本発明の送信増幅器は、
　無線周波数のデジタル信号の複数のビットの各々に対応して設けられた複数のスイッチモード増幅器と、
　前記複数のスイッチモード増幅器の各々の後段に設けられた複数の信号経路部と、を有し、
　前記複数の信号経路部は、
　出力段が互いに直列に接続されるとともに、負荷と並列に接続され、
　前記複数の信号経路部の各々は、
　前記スイッチモード増幅器の後段に設けられ、第１線路の一端が該スイッチモード増幅器に接続され、第２線路の一端が接地された伝送線路トランスと、
　前記伝送線路トランスの後段に設けられ、該伝送線路トランスの第１線路の他端と第２線路の他端との間に接続された出力スイッチ素子と、を有し、
　前記出力スイッチ素子は、
　前記スイッチモード増幅器から電源電圧が出力されている場合は開状態になり、電源電圧が出力されていない場合は閉状態になる。 The transmission amplifier of the present invention includes:
A plurality of switch mode amplifiers provided corresponding to each of the plurality of bits of the radio frequency digital signal;
A plurality of signal path portions provided in the subsequent stage of each of the plurality of switch mode amplifiers,
The plurality of signal path portions are:
The output stages are connected in series with each other and connected in parallel with the load,
Each of the plurality of signal path portions is
A transmission line transformer provided at a subsequent stage of the switch mode amplifier, one end of the first line is connected to the switch mode amplifier, and one end of the second line is grounded;
An output switch element provided at a subsequent stage of the transmission line transformer and connected between the other end of the first line and the other end of the second line of the transmission line transformer;
The output switch element is
When the power supply voltage is output from the switch mode amplifier, the switch is opened. When the power supply voltage is not output, the switch mode amplifier is closed.
　本発明によれば、送信増幅器の広帯域化を図ることができるという効果が得られる。 According to the present invention, there is an effect that the transmission amplifier can be widened.
本発明の一実施形態の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of one Embodiment of this invention. 本発明の一実施形態の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of one Embodiment of this invention. 本発明の一実施形態の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of one Embodiment of this invention. 本発明の一実施形態の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of one Embodiment of this invention. 図１Ａ～図１Ｄに示したスイッチモード増幅器と伝送線路トランスとの接続関係の一例を示す回路図である。FIG. 2 is a circuit diagram showing an example of a connection relationship between a switch mode amplifier and a transmission line transformer shown in FIGS. 1A to 1D. 図１Ａ～図１Ｄに示したスイッチモード増幅器と伝送線路トランスとの接続関係の他の例を示す回路図である。FIG. 7 is a circuit diagram showing another example of the connection relationship between the switch mode amplifier and the transmission line transformer shown in FIGS. 1A to 1D. 本発明の実施例１の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of Example 1 of this invention. 本発明の実施例１の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of Example 1 of this invention. 本発明の実施例１の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of Example 1 of this invention. 本発明の実施例１の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of Example 1 of this invention. 本発明の実施例２の送信増幅器の回路構成を示す回路図である。It is a circuit diagram which shows the circuit structure of the transmission amplifier of Example 2 of this invention. 本発明の実施例２の送信増幅器に用いる２重同軸構造の伝送線路トランスの外観構成を示す図である。It is a figure which shows the external appearance structure of the transmission line transformer of the double coaxial structure used for the transmission amplifier of Example 2 of this invention.
　以下、本発明を実施するための形態について図面を参照して説明する。なお、以下では、説明の簡略化のため、無線周波数のデジタル送信信号が２ビットであると仮定し、各ビットに対応して２つのスイッチモード増幅器を設けた構成を例に挙げて説明する。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following, for the sake of simplicity of explanation, it is assumed that a digital transmission signal of radio frequency is 2 bits, and a configuration in which two switch mode amplifiers are provided corresponding to each bit will be described as an example.
　図１Ａ～図１Ｄに、本実施形態の送信増幅器の回路構成を示す。 1A to 1D show the circuit configuration of the transmission amplifier of the present embodiment.
　図１Ａ～図１Ｄに示すように、本実施形態の送信増幅器は、スイッチモード増幅器１０－１，１０－２と、伝送線路トランス２０－１，２０－２と、スイッチ素子（出力スイッチ素子）３０－１，３０－２と、を有している。 As shown in FIGS. 1A to 1D, the transmission amplifier of this embodiment includes switch mode amplifiers 10-1 and 10-2, transmission line transformers 20-1 and 20-2, and a switch element (output switch element) 30. -1,30-2.
　ここで、スイッチモード増幅器１０－１（第１スイッチモード増幅器）側では、伝送線路トランス２０－１とスイッチ素子３０－１とで第１信号経路部を構成している。また、スイッチモード増幅器１０－２（第２スイッチモード増幅器）側では、伝送線路トランス２０－２とスイッチ素子３０－２とで第２信号経路部を構成している。また、これら２つの信号経路部は、出力段において、互いに直列に接続されると共に、負荷（アンテナ）４０に並列に接続されている。 Here, on the switch mode amplifier 10-1 (first switch mode amplifier) side, the transmission line transformer 20-1 and the switch element 30-1 constitute a first signal path section. On the switch mode amplifier 10-2 (second switch mode amplifier) side, the transmission line transformer 20-2 and the switch element 30-2 constitute a second signal path section. In addition, these two signal path units are connected in series to each other in the output stage, and are connected in parallel to the load (antenna) 40.
　以下、スイッチモード増幅器１０－１側の構成について説明する。 The configuration on the switch mode amplifier 10-1 side will be described below.
　スイッチモード増幅器１０－１は、２ビットのデジタル送信信号の一方のビットに対応して設けられている。 The switch mode amplifier 10-1 is provided corresponding to one bit of the 2-bit digital transmission signal.
　伝送線路トランス２０－１は、スイッチモード増幅器１０－１の後段に設けられており、２つの線路により構成されている。これら２つの線路は、図１Ａ～図１Ｄに示したような巻線や、マイクロストリップ線路で実現することが可能である。 The transmission line transformer 20-1 is provided in the subsequent stage of the switch mode amplifier 10-1, and is composed of two lines. These two lines can be realized by windings as shown in FIGS. 1A to 1D or microstrip lines.
　なお、図１Ａ～図１Ｄは、スイッチモード増幅器１０－１を簡略化して示しており、スイッチモード増幅器１０－１と伝送線路トランス２０－１との具体的な接続関係は、図２または図３のようになる。 1A to 1D show the switch mode amplifier 10-1 in a simplified manner, and the specific connection relationship between the switch mode amplifier 10-1 and the transmission line transformer 20-1 is shown in FIG. 2 or FIG. become that way.
　図２の例では、スイッチモード増幅器１０－１は、ハイサイド側（電源側）とローサイド側（接地側）の各々にスイッチ素子（入力スイッチ素子）１１，１２を備えており、これら２つのスイッチ素子１１，１２が互いに直列に接続された構成である。スイッチ素子１１，１２は、いずれか１つのみが閉状態になるように制御され、スイッチ素子１１が閉状態の場合は電源電圧Ｖ１が出力される。なお、スイッチ素子１１が開状態の場合は、スイッチ素子１２が閉状態になり、接地電圧が出力される。 In the example of FIG. 2, the switch mode amplifier 10-1 includes switch elements (input switch elements) 11 and 12 on the high side (power supply side) and the low side (ground side), respectively. The elements 11 and 12 are connected in series with each other. Only one of the switch elements 11 and 12 is controlled to be in a closed state. When the switch element 11 is in a closed state, the power supply voltage V1 is output. When the switch element 11 is open, the switch element 12 is closed and a ground voltage is output.
　また、図２の例では、伝送線路トランス２０－１の一方の線路（以下、第１線路と称す）の一端がスイッチ素子１１，１２の接続点に接続され、他方の線路（以下、第２線路と称す）の一端は接地されている。 In the example of FIG. 2, one end of one line (hereinafter referred to as a first line) of the transmission line transformer 20-1 is connected to a connection point of the switch elements 11 and 12, and the other line (hereinafter referred to as a second line). One end of the track is called ground.
　一方、図３の例では、スイッチモード増幅器１０－１は、ハイサイド側（電源側）にのみスイッチ素子１１を備えた構成である。スイッチ素子１１が閉状態の場合は電源電圧Ｖ１が出力される。 On the other hand, in the example of FIG. 3, the switch mode amplifier 10-1 is configured to include the switch element 11 only on the high side (power supply side). When the switch element 11 is closed, the power supply voltage V1 is output.
　また、図３の例では、伝送線路トランス２０－１の第１線路の一端がスイッチ素子１１に接続され、第２線路の一端は接地されている。 In the example of FIG. 3, one end of the first line of the transmission line transformer 20-1 is connected to the switch element 11, and one end of the second line is grounded.
　スイッチ素子３０－１は、伝送線路トランス２０－１の後段に設けられており、伝送線路トランス２０－１の第１線路の他端と第２線路の他端との間に接続されている。 The switch element 30-1 is provided in the subsequent stage of the transmission line transformer 20-1, and is connected between the other end of the first line and the other end of the second line of the transmission line transformer 20-1.
　また、スイッチ素子３０－１は、スイッチモード増幅器１０－１の出力電圧に応じて、以下のスイッチング動作を行う。 Further, the switch element 30-1 performs the following switching operation in accordance with the output voltage of the switch mode amplifier 10-1.
　例えば、スイッチモード増幅器１０－１のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ１が出力されている場合は、スイッチ素子３０－１は、開状態（Open）になる（図１Ａ、図１Ｂ参照）。 For example, when the switch element 11 of the switch mode amplifier 10-1 is in the closed state (Short) and the power supply voltage V1 is output, the switch element 30-1 is in the open state (Open) (FIG. 1A, FIG. 1B).
　一方、スイッチモード増幅器１０－１のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ１が出力されていない場合は、スイッチ素子３０－１は、閉状態（Short）になる（図１Ｃ、図１Ｄ参照）。 On the other hand, when the switch element 11 of the switch mode amplifier 10-1 is in the open state (Open) and the power supply voltage V1 is not output, the switch element 30-1 is in the closed state (Short) (FIG. 1C, FIG. 1D).
　ここで、スイッチ素子３０－１のスイッチング動作は、スイッチモード増幅器１０－１の出力に同期して行われ、かつ、伝送線路トランス２０－１での遅延分だけタイミングを修正する必要がある。 Here, the switching operation of the switch element 30-1 is performed in synchronization with the output of the switch mode amplifier 10-1, and it is necessary to correct the timing by the amount of delay in the transmission line transformer 20-1.
　そのため、別個に制御部（不図示）を設け、制御部が、スイッチ素子３０－１を上記のスイッチング動作をするように制御しても良い。ただし、後述する実施例のように、スイッチ素子３０－１をダイオードで構成すれば、上記の制御部を設けなくても、スイッチモード増幅器１０－１の出力に同期して、かつ、伝送線路トランス２０－１での遅延分だけ遅れたタイミングでスイッチング動作を行うことになるため、上記の制御部は不要になる。 Therefore, a separate control unit (not shown) may be provided, and the control unit may control the switching element 30-1 to perform the above switching operation. However, if the switch element 30-1 is formed of a diode as in an embodiment described later, the transmission line transformer can be synchronized with the output of the switch mode amplifier 10-1 without providing the control unit. Since the switching operation is performed at a timing delayed by the delay of 20-1, the above control unit is not necessary.
　また、図２の例では、ローサイド側（接地側）にスイッチ素子１２を設けているために、スイッチ素子３０－１は設けられていなくとも所望の電圧を出力することが可能であるし、したがって別個に制御部（不図示）を設ける必要もない。しかし、より高周波で動作をさせるためには、特に接地電圧を出力する際に伝送線路トランス２０－１で発生する遅延を抑制することができるので、スイッチ素子３０－１を設けておくことが望ましい。 In the example of FIG. 2, since the switch element 12 is provided on the low side (ground side), a desired voltage can be output even if the switch element 30-1 is not provided. There is no need to provide a separate control unit (not shown). However, in order to operate at a higher frequency, it is desirable to provide the switch element 30-1 because the delay generated in the transmission line transformer 20-1 can be suppressed particularly when the ground voltage is output. .
　なお、スイッチ素子３０－１は、ダイオード以外にも、例えば、電子スイッチで構成することが可能であるが、その場合は上記の制御部を設ける必要がある。 In addition, the switch element 30-1 can be constituted by, for example, an electronic switch in addition to the diode, but in this case, the above-described control unit needs to be provided.
　また、伝送線路トランス２０－１の特性インピーダンスは、任意に設定することが可能であり、例えば、負荷４０の特性インピーダンスが５０Ωの場合、これと整合するように、５０Ωに設定することが考えられる（この場合、伝送線路トランス２０－２の特性インピーダンスも同様に５０Ωに設定することが考えられる）。 Further, the characteristic impedance of the transmission line transformer 20-1 can be arbitrarily set. For example, when the characteristic impedance of the load 40 is 50Ω, it may be set to 50Ω so as to be matched with this. (In this case, it is conceivable that the characteristic impedance of the transmission line transformer 20-2 is also set to 50Ω).
　なお、スイッチモード増幅器１０－２側の構成は、スイッチモード増幅器１０－１側の構成と同様であるため、説明を省略する。 The configuration on the switch mode amplifier 10-2 side is the same as the configuration on the switch mode amplifier 10-1 side, and the description thereof is omitted.
　以下、本実施形態の送信増幅器の動作について説明する。
（Ａ）電源電圧Ｖ１，Ｖ２を出力
　図１Ａに示すように、スイッチモード増幅器１０－１，１０－２のスイッチ素子１１が共に閉状態で（Short）、電源電圧Ｖ１，Ｖ２が共に出力されている場合は、スイッチ素子３０－１，３０－２は共に開状態（Open）になる。 Hereinafter, the operation of the transmission amplifier of this embodiment will be described.
(A) Output power supply voltages V1 and V2 As shown in FIG. 1A, the switch elements 11 of the switch mode amplifiers 10-1 and 10-2 are both closed (Short), and both power supply voltages V1 and V2 are output. When the switch elements 30-1 and 30-2 are in the open state, the switch elements 30-1 and 30-2 are both open.
　この場合、電源電圧Ｖ１，Ｖ２は、伝送線路トランス２０－１，２０－２を介して負荷４０側に出力される。 In this case, the power supply voltages V1 and V2 are output to the load 40 via the transmission line transformers 20-1 and 20-2.
　その結果、負荷４０における電圧は、Ｖ１＋Ｖ２となる。
（Ｂ）電源電圧Ｖ１を出力
　図１Ｂに示すように、スイッチモード増幅器１０－１のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ１が出力されているが、スイッチモード増幅器１０－２のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ２が出力されていない場合は、スイッチ素子３０－１は開状態（Open）になり、スイッチ素子３０－２は閉状態（Short）になる。 As a result, the voltage at the load 40 is V1 + V2.
(B) Output power supply voltage V1 As shown in FIG. 1B, the switch element 11 of the switch mode amplifier 10-1 is closed (Short) and the power supply voltage V1 is output. When the switch element 11 is in the open state (Open) and the power supply voltage V2 is not output, the switch element 30-1 is in the open state (Open), and the switch element 30-2 is in the closed state (Short).
　この場合、電源電圧Ｖ１は、スイッチ素子３０－１を介して負荷４０側に出力されるが、電源電圧Ｖ２は、負荷４０側に出力されない。また、スイッチ素子３０－２から見てスイッチモード増幅器１０－２側には、コモンモード電流が流れない。 In this case, the power supply voltage V1 is output to the load 40 side via the switch element 30-1, but the power supply voltage V2 is not output to the load 40 side. Further, no common mode current flows on the switch mode amplifier 10-2 side as viewed from the switch element 30-2.
　その結果、負荷４０における電圧は、Ｖ１となる。
（Ｃ）電源電圧Ｖ２を出力
　図１Ｃに示すように、スイッチモード増幅器１０－２のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ２が出力されているが、スイッチモード増幅器１０－１のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ１が出力されていない場合は、スイッチ素子３０－２は開状態（Open）になり、スイッチ素子３０－１は閉状態（Short）になる。 As a result, the voltage at the load 40 is V1.
(C) Output power supply voltage V2 As shown in FIG. 1C, the switch element 11 of the switch mode amplifier 10-2 is closed (Short) and the power supply voltage V2 is output. When the switch element 11 is in the open state (Open) and the power supply voltage V1 is not output, the switch element 30-2 is in the open state (Open) and the switch element 30-1 is in the closed state (Short).
　この場合、電源電圧Ｖ２は、スイッチ素子３０－２を介して負荷４０側に出力されるが、電源電圧Ｖ１は、負荷４０側に出力されない。また、スイッチ素子３０－１から見てスイッチモード増幅器１０－１側には、コモンモード電流が流れない。 In this case, the power supply voltage V2 is output to the load 40 side via the switch element 30-2, but the power supply voltage V1 is not output to the load 40 side. Further, the common mode current does not flow to the switch mode amplifier 10-1 side when viewed from the switch element 30-1.
　その結果、負荷４０における電圧は、Ｖ２となる。
（Ｄ）電源電圧Ｖ１，Ｖ２を非出力
　図１Ｄに示すように、スイッチモード増幅器１０－１，１０－２のスイッチ素子１１が共に開状態で（Open）、電源電圧Ｖ１，Ｖ２が共に出力されていない場合は、スイッチ素子３０－１，３０－２は共に閉状態（Short）になる。 As a result, the voltage at the load 40 is V2.
(D) Power supply voltages V1 and V2 are not output. As shown in FIG. 1D, the switch elements 11 of the switch mode amplifiers 10-1 and 10-2 are both open (Open), and both power supply voltages V1 and V2 are output. If not, the switch elements 30-1 and 30-2 are both closed (Short).
　この場合、電源電圧Ｖ１，Ｖ２は、負荷４０側に出力されない。 In this case, the power supply voltages V1 and V2 are not output to the load 40 side.
　その結果、負荷４０における電圧は、０となる。 As a result, the voltage at the load 40 becomes zero.
　以上の通り、本実施形態の送信増幅器においては、スイッチモード増幅器１０－１，１０－２の出力電圧を電圧合成した電圧が負荷４０側に現れる。したがって、多ビットのデジタル送信信号を無線周波数で合成することができる。 As described above, in the transmission amplifier according to the present embodiment, a voltage obtained by combining the output voltages of the switch mode amplifiers 10-1 and 10-2 appears on the load 40 side. Therefore, a multi-bit digital transmission signal can be synthesized at a radio frequency.
　また、非特許文献１のように１／４波長伝送線路を用いる必要がなく、使用する周波数帯域の制限を受けないため、広帯域化を図ることができる。 Further, unlike the non-patent document 1, it is not necessary to use a quarter wavelength transmission line, and since the frequency band to be used is not limited, the bandwidth can be increased.
　また、例えば、図２に示したスイッチモード増幅器１０－１を適用した場合、ローサイド側（接地側）のスイッチ素子１２が閉状態のとき、スイッチ素子３０－１が閉状態（Short）になる。その結果、伝送線路トランス２０－１の出力端子も接地されることになる。 For example, when the switch mode amplifier 10-1 shown in FIG. 2 is applied, when the switch element 12 on the low side (ground side) is in the closed state, the switch element 30-1 is in the closed state (Short). As a result, the output terminal of the transmission line transformer 20-1 is also grounded.
　一方、図３に示したスイッチモード増幅器１０－１を適用した場合、ハイサイド側（電源側）のスイッチ素子１２が開状態のとき、スイッチ素子３０－１が閉状態（Short）になる。その結果、伝送線路トランス２０－１の出力端子も接地されるため、ローサイド側（接地側）のスイッチ素子が不要になる。よって、スイッチモード増幅器１０－１の構成の簡素化、低コスト化を図ることもできる（スイッチモード増幅器１０－２も同様）。 On the other hand, when the switch mode amplifier 10-1 shown in FIG. 3 is applied, when the switch element 12 on the high side (power supply side) is in the open state, the switch element 30-1 is in the closed state (Short). As a result, since the output terminal of the transmission line transformer 20-1 is also grounded, a low-side (ground-side) switching element is not necessary. Therefore, the configuration of the switch mode amplifier 10-1 can be simplified and the cost can be reduced (the same applies to the switch mode amplifier 10-2).
　以下に、本実施形態の送信増幅器の具体的な実施例について説明する。 Hereinafter, specific examples of the transmission amplifier according to the present embodiment will be described.
（１）実施例１
　図４Ａ～図４Ｄに、本実施例の送信増幅器の回路構成を示す。 (1) Example 1
4A to 4D show circuit configurations of the transmission amplifier of this embodiment.
　図４Ａ～図４Ｄに示すように、本実施例は、図１Ａ～図１Ｄに示したスイッチ素子３０－１，３０－２を、それぞれダイオード３１－１，３１－２で実現している。 As shown in FIGS. 4A to 4D, in this embodiment, the switch elements 30-1 and 30-2 shown in FIGS. 1A to 1D are realized by diodes 31-1 and 31-2, respectively.
　以下、スイッチモード増幅器１０－１側の構成について説明する。 The configuration on the switch mode amplifier 10-1 side will be described below.
　ダイオード３１－１は、伝送線路トランス２０－１の後段に設けられており、伝送線路トランス２０－１の第１線路の他端にカソード素子が接続され、第２線路の他端にアノード素子が接続されている。 The diode 31-1 is provided at the subsequent stage of the transmission line transformer 20-1, a cathode element is connected to the other end of the first line of the transmission line transformer 20-1, and an anode element is connected to the other end of the second line. It is connected.
　そのため、スイッチモード増幅器１０－１のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ１が出力されている場合は、ダイオード３１－１は、逆方向電圧が印加された状態になるため、電流が流れず、実質的に開状態（Open）になる（図４Ａ、図４Ｂ参照）。 Therefore, when the switch element 11 of the switch mode amplifier 10-1 is in a closed state (Short) and the power supply voltage V1 is output, the diode 31-1 is in a state where a reverse voltage is applied. Does not flow, and substantially becomes an open state (see FIGS. 4A and 4B).
　一方、スイッチモード増幅器１０－１のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ１が出力されていない場合は、ダイオード３１－１は、順方向電圧が印加された状態になるため、順方向（第２線路側から第１線路側に向かう方向）に電流が流れ、実質的に閉状態（Short）になる（図４Ｃ、図４Ｄ参照）。 On the other hand, when the switch element 11 of the switch mode amplifier 10-1 is in an open state (Open) and the power supply voltage V1 is not output, the diode 31-1 is in a state in which a forward voltage is applied. A current flows in a direction (a direction from the second line side toward the first line side), and a substantially closed state (Short) is obtained (see FIGS. 4C and 4D).
　なお、スイッチモード増幅器１０－２側の構成は、スイッチモード増幅器１０－１側の構成と同様であるため、説明を省略する。 The configuration on the switch mode amplifier 10-2 side is the same as the configuration on the switch mode amplifier 10-1 side, and the description thereof is omitted.
　以下、本実施形態の送信増幅器の動作について説明する。
（Ａ）電源電圧Ｖ１，Ｖ２を出力
　図４Ａに示すように、スイッチモード増幅器１０－１，１０－２のスイッチ素子１１が共に閉状態で（Short）、電源電圧Ｖ１，Ｖ２が共に出力されている場合は、ダイオード３１－１，３１－２は共に開状態（Open）になる。 Hereinafter, the operation of the transmission amplifier of this embodiment will be described.
(A) Outputting power supply voltages V1 and V2 As shown in FIG. 4A, the switch elements 11 of the switch mode amplifiers 10-1 and 10-2 are both closed (Short), and both power supply voltages V1 and V2 are output. If so, both the diodes 31-1 and 31-2 are in the open state (Open).
　この場合、電源電圧Ｖ１，Ｖ２は、伝送線路トランス２０－１，２０－２を介して負荷４０側に出力される。 In this case, the power supply voltages V1 and V2 are output to the load 40 via the transmission line transformers 20-1 and 20-2.
　その結果、負荷４０における電圧は、Ｖ１＋Ｖ２となる。
（Ｂ）電源電圧Ｖ１を出力
　図４Ｂに示すように、スイッチモード増幅器１０－１のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ１を出力されているが、スイッチモード増幅器１０－２のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ２が出力されていない場合は、ダイオード３１－１は開状態（Open）になり、ダイオード３１－２は閉状態（Short）になる。 As a result, the voltage at the load 40 is V1 + V2.
(B) Output power supply voltage V1 As shown in FIG. 4B, the switch element 11 of the switch mode amplifier 10-1 is closed (Short) and the power supply voltage V1 is output. When the switch element 11 is in an open state (Open) and the power supply voltage V2 is not output, the diode 31-1 is in an open state (Open) and the diode 31-2 is in a closed state (Short).
　この場合、電源電圧Ｖ１は、ダイオード３１－１を介して負荷４０側に出力されるが、電源電圧Ｖ２は、負荷４０側に出力されない。また、ダイオード３１－２から見てスイッチモード増幅器１０－２側には、コモンモード電流が流れない。また、ダイオード３１－２では、順方向電圧Ｖｆ分の電圧降下が生じている。 In this case, the power supply voltage V1 is output to the load 40 side via the diode 31-1, but the power supply voltage V2 is not output to the load 40 side. Further, no common mode current flows to the switch mode amplifier 10-2 side as viewed from the diode 31-2. In addition, the diode 31-2 has a voltage drop corresponding to the forward voltage Vf.
　その結果、負荷４０における電圧は、Ｖ１－Ｖｆとなる。ただし、Ｖｆは、Ｖ１に比べて十分に小さいため、Ｖ１－Ｖｆ≒Ｖ１と近似できる。
（Ｃ）電源電圧Ｖ２を出力
　図４Ｃに示すように、スイッチモード増幅器１０－２のスイッチ素子１１が閉状態で（Short）、電源電圧Ｖ２が出力されているが、スイッチモード増幅器１０－１のスイッチ素子１１が開状態で（Open）、電源電圧Ｖ１が出力されていない場合は、ダイオード３１－２は開状態（Open）になり、ダイオード３１－１は閉状態（Short）になる。 As a result, the voltage at the load 40 is V1-Vf. However, since Vf is sufficiently smaller than V1, it can be approximated as V1−Vf≈V1.
(C) Output power supply voltage V2 As shown in FIG. 4C, the switch element 11 of the switch mode amplifier 10-2 is closed (Short), and the power supply voltage V2 is output. When the switch element 11 is in the open state (Open) and the power supply voltage V1 is not output, the diode 31-2 is in the open state (Open) and the diode 31-1 is in the closed state (Short).
　この場合、電源電圧Ｖ２は、ダイオード３１－２を介して負荷４０側に出力されるが、電源電圧Ｖ１は、負荷４０側に出力されない。また、ダイオード３１－１から見てスイッチモード増幅器１０－１側には、コモンモード電流が流れない。また、ダイオード３１－１では、順方向電圧Ｖｆ分の電圧降下が生じている。 In this case, the power supply voltage V2 is output to the load 40 side via the diode 31-2, but the power supply voltage V1 is not output to the load 40 side. Further, no common mode current flows on the switch mode amplifier 10-1 side as viewed from the diode 31-1. In the diode 31-1, a voltage drop corresponding to the forward voltage Vf occurs.
　その結果、負荷４０における電圧は、Ｖ２－Ｖｆとなる。ただし、Ｖｆは、Ｖ２に比べて十分に小さいため、Ｖ２－Ｖｆ≒Ｖ２と近似できる。
（Ｄ）電源電圧Ｖ１，Ｖ２を非出力
　図４Ｄに示すように、スイッチモード増幅器１０－１，１０－２のスイッチ素子１１が共に開状態で（Open）、電源電圧Ｖ１，Ｖ２が共に出力されていない場合は、ダイオード３１－１，３１－２は共に閉状態（Short）になる。 As a result, the voltage at the load 40 is V2-Vf. However, since Vf is sufficiently smaller than V2, it can be approximated as V2−Vf≈V2.
(D) Power supply voltages V1 and V2 are not output As shown in FIG. 4D, the switch elements 11 of the switch mode amplifiers 10-1 and 10-2 are both open (Open), and both power supply voltages V1 and V2 are output. If not, the diodes 31-1 and 31-2 are both closed (Short).
　この場合、電源電圧Ｖ１，Ｖ２は、負荷４０側に出力されない。 In this case, the power supply voltages V1 and V2 are not output to the load 40 side.
　その結果、負荷４０における電圧は、０となる。 As a result, the voltage at the load 40 becomes zero.
　以上の通り、本実施例の送信増幅器においても、多ビットのデジタル送信信号を無線周波数で合成することができる。 As described above, even in the transmission amplifier of this embodiment, a multi-bit digital transmission signal can be synthesized at a radio frequency.
　また、非特許文献１のように１／４波長伝送線路を用いる必要がなく、使用する周波数帯域の制限を受けないため、広帯域化を図ることができる。 Further, unlike the non-patent document 1, it is not necessary to use a quarter wavelength transmission line, and since the frequency band to be used is not limited, the bandwidth can be increased.
　また、図３に示したスイッチモード増幅器１０－１を適用した場合、ローサイド側（接地側）のスイッチ素子が不要になるため、スイッチモード増幅器１０－１の構成の簡素化、低コスト化を図ることもできる（スイッチモード増幅器１０－２も同様）。
（２）実施例２
　本実施例は、実施例１の送信増幅器を構成する第１信号経路部と第２信号経路部の部分を、２重同軸構造の伝送線路トランスで実現する例である。 Further, when the switch mode amplifier 10-1 shown in FIG. 3 is applied, the switch element on the low side (ground side) is not required, so that the configuration of the switch mode amplifier 10-1 is simplified and the cost is reduced. (The same applies to the switch mode amplifier 10-2).
(2) Example 2
The present embodiment is an example in which the first signal path section and the second signal path section constituting the transmission amplifier according to the first embodiment are realized by a transmission line transformer having a double coaxial structure.
　図５に、本実施例の送信増幅器の回路構成を示す。 FIG. 5 shows the circuit configuration of the transmission amplifier of this embodiment.
　図５に示すように、本実施例の送信増幅器は、回路構成自体は実施例１と同様である。 As shown in FIG. 5, the circuit configuration of the transmission amplifier of this embodiment is the same as that of the first embodiment.
　図６に、本実施例の送信増幅器に用いる２重同軸構造の伝送線路トランス５０の外観構成を示す。なお、図６において、Ｔ１～Ｔ７は、図５のＴ１～Ｔ７の位置に対応している。 FIG. 6 shows an external configuration of a transmission line transformer 50 having a double coaxial structure used in the transmission amplifier of this embodiment. In FIG. 6, T1 to T7 correspond to the positions of T1 to T7 in FIG.
　図６に示した２重同軸構造の伝送線路トランス５０は、中心から外側に向けて、中心導体５１と、内導体５２と、外導体５３と、がこの順に形成されている。また、中心導体５１と内導体５２の間には誘電体５４（誘電率：ε１）が充填され、内導体５２と外導体５３の間には誘電体５５（誘電率：ε２）が充填されている。また、２重同軸構造の伝送線路トランス５０の外部は、広い周波数帯域にわたって伝送線路トランスの入出力のアイソレーションを高めたりコモンモード電流を除去したりするために、フェライトスリーブ（不図示）で囲まれていることが望ましい。 In the transmission line transformer 50 having a double coaxial structure shown in FIG. 6, a center conductor 51, an inner conductor 52, and an outer conductor 53 are formed in this order from the center toward the outside. Further, a dielectric 54 (dielectric constant: ε1) is filled between the center conductor 51 and the inner conductor 52, and a dielectric 55 (dielectric constant: ε2) is filled between the inner conductor 52 and the outer conductor 53. Yes. In addition, the outside of the transmission line transformer 50 having a double coaxial structure is surrounded by a ferrite sleeve (not shown) in order to increase the input / output isolation of the transmission line transformer and to remove the common mode current over a wide frequency band. It is desirable that
　なお、図６においては、スイッチモード増幅器１０－２の電源電圧Ｖ２の極性を、図５とは逆にして適用している（すなわち、図５において、電源電圧Ｖ２の極性を逆にし、位置Ｔ４でなく位置Ｔ３を接地した回路構成に適用するイメージ）。また、伝送線路トランス２０－１，２０－２の特性インピーダンスは、誘電体５４，５５の誘電率ε１，ε２や、同軸線路の半径を変更することによって、設定可能である。 In FIG. 6, the polarity of the power supply voltage V2 of the switch mode amplifier 10-2 is applied opposite to that in FIG. 5 (that is, the polarity of the power supply voltage V2 is reversed in FIG. And an image applied to a circuit configuration in which the position T3 is grounded). The characteristic impedance of the transmission line transformers 20-1 and 20-2 can be set by changing the dielectric constants ε1 and ε2 of the dielectrics 54 and 55 and the radius of the coaxial line.
　２重同軸構造の伝送線路トランス５０の一端（図６の左端）においては、中心導体５１がスイッチモード増幅器１０－１に接続され（位置Ｔ１）、内導体５２が接地され（位置Ｔ２，Ｔ３）、外導体５３がスイッチモード増幅器１０－２に接続されている（位置Ｔ４）。 At one end (left end in FIG. 6) of the transmission line transformer 50 having a double coaxial structure, the center conductor 51 is connected to the switch mode amplifier 10-1 (position T1), and the inner conductor 52 is grounded (positions T2 and T3). The outer conductor 53 is connected to the switch mode amplifier 10-2 (position T4).
　また、２重同軸構造の伝送線路トランス５０の他端（図６の右端）においては、中心導体５１が負荷４０に接続され（位置Ｔ５）、内導体５２を接地しない状態（Open）にしている（位置Ｔ６）。ここで、伝送線路トランス５０の一端から他端に向けて誘電体５４を流れる電流は、伝送線路トランス５０の他端において、内導体５２を介して折り返されて、誘電体５５に流れることになるため、位置Ｔ６の部分は導通状態になっている。また、外導体５３がキャパシタを介してＲＦ接地されている（位置Ｔ７）。ここで、外導体５３を接地でなくＲＦ接地しているのは、スイッチモード増幅器１０－２の電源が直流的に接地されることを回避するためである。 At the other end (right end in FIG. 6) of the transmission line transformer 50 having a double coaxial structure, the center conductor 51 is connected to the load 40 (position T5), and the inner conductor 52 is not grounded (Open). (Position T6). Here, the current flowing through the dielectric 54 from one end of the transmission line transformer 50 toward the other end is folded back via the inner conductor 52 at the other end of the transmission line transformer 50 and flows into the dielectric 55. Therefore, the portion at position T6 is in a conductive state. The outer conductor 53 is RF-grounded via a capacitor (position T7). Here, the reason why the outer conductor 53 is grounded instead of being grounded is to prevent the power source of the switch mode amplifier 10-2 from being grounded in a DC manner.
　以上の通り、本実施例の送信増幅器においては、第１信号経路部と第２信号経路部の部分を、２重同軸構造の伝送線路トランスで実現しているため、送信増幅器自体の小型化および軽量化を図ることができる。その他の効果は実施例１と同様である。 As described above, in the transmission amplifier of the present embodiment, the first signal path portion and the second signal path portion are realized by a transmission line transformer having a double coaxial structure. Weight reduction can be achieved. Other effects are the same as those of the first embodiment.
　以上、実施形態および実施例を参照して本発明を説明したが、本発明は上記実施形態および上記実施例に限定されるものではない。本発明の構成や詳細には、本発明の範囲内で当業者が理解し得る様々な変更をすることができる。 As mentioned above, although this invention was demonstrated with reference to embodiment and an Example, this invention is not limited to the said embodiment and said Example. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
　例えば、上記実施形態においては、デジタル送信信号が２ビットであると仮定したが、本発明はこれに限らず、多ビットのデジタル送信信号に対応可能である。 For example, in the above-described embodiment, it is assumed that the digital transmission signal is 2 bits. However, the present invention is not limited to this, and can accommodate a multi-bit digital transmission signal.
　本出願は、２０１２年１０月１７日に出願された日本出願特願２０１２－２２９６２５を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2012-229625 filed on October 17, 2012, the entire disclosure of which is incorporated herein.

Claims (4)

  1. 　無線周波数のデジタル信号の複数のビットの各々に対応して設けられた複数のスイッチモード増幅器と、
    　前記複数のスイッチモード増幅器の各々の後段に設けられた複数の信号経路部と、を有し、
    　前記複数の信号経路部は、
    　出力段が互いに直列に接続されるとともに、負荷と並列に接続され、
    　前記複数の信号経路部の各々は、
    　前記スイッチモード増幅器の後段に設けられ、第１線路の一端が該スイッチモード増幅器に接続され、第２線路の一端が接地された伝送線路トランスと、
    　前記伝送線路トランスの後段に設けられ、該伝送線路トランスの第１線路の他端と第２線路の他端との間に接続された出力スイッチ素子と、を有し、
    　前記出力スイッチ素子は、
    　前記スイッチモード増幅器から電源電圧が出力されている場合は開状態になり、電源電圧が出力されていない場合は閉状態になる、送信増幅器。     A plurality of switch mode amplifiers provided corresponding to each of the plurality of bits of the radio frequency digital signal;
    A plurality of signal path portions provided in the subsequent stage of each of the plurality of switch mode amplifiers,
    The plurality of signal path portions are:
    The output stages are connected in series with each other and connected in parallel with the load,
    Each of the plurality of signal path portions is
    A transmission line transformer provided at a subsequent stage of the switch mode amplifier, one end of the first line is connected to the switch mode amplifier, and one end of the second line is grounded;
    An output switch element provided at a subsequent stage of the transmission line transformer and connected between the other end of the first line and the other end of the second line of the transmission line transformer;
    The output switch element is
    A transmission amplifier which is in an open state when a power supply voltage is output from the switch mode amplifier and is in a closed state when a power supply voltage is not output.
  2. 　前記出力スイッチ素子は、
    　前記伝送線路トランスの第１線路の他端にカソード端子が接続され、第２線路の他端にアノード端子が接続されたダイオードである、請求項１に記載の送信増幅器。     The output switch element is
    The transmission amplifier according to claim 1, wherein the transmission line transformer is a diode having a cathode terminal connected to the other end of the first line and an anode terminal connected to the other end of the second line.
  3. 　前記複数のスイッチモード増幅器は、
    　第１スイッチモード増幅器と、
    　第２スイッチモード増幅器と、の２つから構成され、
    　前記複数の信号経路部は、
    　第１信号経路部と、
    　第２信号経路部と、の２つから構成され、
    　前記第１信号経路部および前記第２信号経路部は、
    　中心から外側に向けて、中心導体と、内導体と、外導体と、がこの順に形成された、２重同軸構造の伝送線路トランスで構成され、
    　前記２重同軸構造の伝送線路トランスの一端において、前記中心導体が前記第１スイッチモード増幅器に接続され、前記内導体が接地され、前記外導体が前記第２スイッチモード増幅器に接続され、
    　前記２重同軸構造の伝送線路トランスの他端において、前記中心導体が前記負荷に接続され、前記外導体がＲＦ接地されている、請求項２に記載の電力増幅器。     The plurality of switch mode amplifiers include:
    A first switch mode amplifier;
    And a second switch mode amplifier.
    The plurality of signal path portions are:
    A first signal path;
    A second signal path section, and
    The first signal path section and the second signal path section are
    A center conductor, an inner conductor, and an outer conductor are formed in this order from the center to the outside, and are composed of a transmission line transformer having a double coaxial structure.
    At one end of the double coaxial transmission line transformer, the central conductor is connected to the first switch mode amplifier, the inner conductor is grounded, and the outer conductor is connected to the second switch mode amplifier.
    The power amplifier according to claim 2, wherein the central conductor is connected to the load and the outer conductor is RF-grounded at the other end of the transmission line transformer having the double coaxial structure.
  4. 　前記複数のスイッチモード増幅器の各々は、
    　一端が電源に接続された入力スイッチ素子から構成され、
    　前記入力スイッチ素子の他端が前記第１線路の一端に接続される、請求項１から３のいずれか１項に記載の送信増幅器。     Each of the plurality of switch mode amplifiers includes:
    Consists of an input switch element with one end connected to the power supply
    The transmission amplifier according to claim 1, wherein the other end of the input switch element is connected to one end of the first line.
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