JP2009055206A - High frequency amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a high frequency amplifier capable of canceling amplification of a high frequency signal of a frequency band which becomes unnecessary among a plurality of frequency bands, at a low cost. <P>SOLUTION: A power amplifier 44 amplifies and outputs output signals supplied from a voltage amplifier 6 for low VHF band and a voltage amplifier 34 for high VHF band. Changeover switches 4, 10 are provided corresponding to the voltage amplifier 6 for low VHF band, and change over switches 32, 38 are provided corresponding to the voltage amplifier 34 for high VHF band, respectively, and voltage is cut off in the voltage amplifier in the frequency band whose amplification becomes unnecessary, by the changeover switch corresponding to the amplifier. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-frequency amplifier, and more particularly to an amplifier that amplifies high-frequency signals in a plurality of frequency bands.

  The high-frequency amplifier may be used as a booster that amplifies a terrestrial analog television broadcast signal transmitted in, for example, the UHF band and the VHF band. By the way, as a television broadcast, in addition to the terrestrial analog broadcast performed conventionally, the terrestrial digital broadcast is started using the UHF band, and the terrestrial analog broadcast ends in 2011. After the end of analog terrestrial broadcasting, if the amplification of the VHF band in which the terrestrial analog broadcast was performed in the booster is continued, other high-frequency signals instead of the analog TV broadcast will be amplified, and the terrestrial digital broadcast signal of the UHF band will be amplified. May interfere with amplification.

  In order to improve this point, for example, a technique as disclosed in Patent Document 1 has been proposed. In this technique, an amplifier for the UHF band and an amplifier for the VHF band are provided. The power supply section for these amplifiers generates two types of DC voltages. When one of the DC voltages is supplied, the power supply to the amplifier for the VHF band is stopped and the power supply to the amplifier for the UHF band is supplied. When the other DC voltage is supplied, power is supplied to each of the UHF band and VHF band amplifiers.

JP 2006-33364 A

  According to the technique of Patent Document 1, the operation of the VHF band amplifier can be stopped. However, in this configuration, both the VHF band amplifier and the UHF band amplifier must be provided with a power amplifier, which increases the cost of the high-frequency amplifier.

  An object of the present invention is to provide a low-cost high-frequency amplifier capable of stopping amplification of a high-frequency signal in a frequency band that has become unnecessary among different frequency bands.

  The high-frequency amplifier of one embodiment of the present invention includes a plurality of pre-amplifiers that amplify high-frequency signals in different frequency bands. These pre-amplification means can be, for example, those that amplify the UHF band and those that amplify the VHF band, and can be, for example, a low VHF band and a high VHF band. One final stage amplification means amplifies and outputs the output signal supplied from these previous stage amplification means. In other words, the final stage amplification means is common to the plurality of previous stage amplification means. The final stage amplifying means is continuously supplied with power. This final stage amplification means is preferably a power amplification means. Variable attenuating means is provided between the output side of at least selected one of the preceding stage amplifying means and the input side of the final stage amplifying means. The variable attenuating means changes the attenuation amount according to the supplied control signal, and impedance-matches with the final stage amplifying means when the control signal is not supplied. The switching means does not supply power to the selected pre-amplifying means, and also does not supply the control signal to the variable attenuation means.

  In the high-frequency amplifier configured as described above, in the state where the power supply to the selected pre-stage amplifying means is supplied by the switching means, the output signals from all the pre-stage amplifying means are amplified by the final stage amplifying means, Is output. In a state where the power supply to the selected pre-amplifier is interrupted by the switching unit, the output signal from the pre-amplifier other than the selected pre-amplifier is amplified and output by the final amplifier. Therefore, amplification of a high frequency signal in a frequency band that does not require amplification is not performed. In addition, since one final stage amplifying means is provided in common for each preceding stage amplifying means, the cost can be reduced. Further, simply shutting off the power supply to the selected preamplifier means causes impedance mismatch in the final amplifier means, and the output signal from the preamplifier means other than the selected preamplifier means is the final amplifier means. Although the variable attenuating means is impedance matched with the final stage amplifying means when the power is not supplied, the output signal from the previous stage amplifying means other than the selected previous stage amplifying means is good by the final stage amplifying means. Is amplified. It is possible to adjust the gain of the selected pre-amplifying means by providing an adjusting means for adjusting the value of the control signal to the variable attenuating means.

  The high-frequency amplifier according to another aspect of the present invention also includes a plurality of previous-stage amplifying means and one final-stage amplifying means as described above. A plurality of switching means are provided corresponding to the respective pre-amplifying means. Each switching means switches to one of supply and shut-off of the operating power to the corresponding pre-stage amplification means.

  In the high-frequency amplifier configured as described above, unnecessary amplification can be stopped by shutting off the power to the desired previous stage amplification means by the switching means corresponding to the desired one among the previous stage amplification means. In addition, since only one final stage amplifying means is provided in common for each previous stage amplifying means, the cost can be reduced.

  Furthermore, variable attenuation means can be provided between the output side of each pre-stage amplification means and the input side of the final-stage amplification means. These variable attenuating means change the attenuation amount according to the supplied control signal, and impedance match with the final stage amplifying means when the control signal is not supplied. Each of the variable attenuation means corresponds to each of the switching means, and the control signal is not supplied when the corresponding switching means is in the power-off state.

  With this configuration, since the variable attenuating means on the output side of the previous stage amplifying means whose power is cut off is impedance-matched with the final stage amplifying means, the power is supplied from the previous stage amplifying means that performs amplification. There is no adverse effect on the amplification of the output signal by the final stage amplification means.

  As described above, according to the present invention, a high-frequency amplifier that can stop amplification of a high-frequency signal in a frequency band that has become unnecessary can be realized at low cost.

  A high-frequency amplifier according to an embodiment of the present invention amplifies terrestrial analog television broadcast signals in a plurality of frequency bands, for example, a high VHF band (170 to 222 MHz band) and a low VHF band (70 to 108 MHz band). This high-frequency amplifier is used, for example, as an amplifier that is interposed in the transmission line of the common hearing system, for example, a trunk amplifier.

  This booster has a duplexer 2 to which a terrestrial analog television broadcast signal in a high VHF band and a low VHF band is supplied. The low VHF band terrestrial analog television broadcast signal demultiplexed by the demultiplexer 2 is input to the input side of the preamplifier means, for example, the low VHF band voltage amplifier 6 via the contact 4a and the contact 4b of the changeover switch 4. It is connected. The changeover switch 4 also has a contact 4c, and a resistor 8 for impedance matching is connected between the contact 4c and a reference potential, for example, a ground potential. The contact 4a of the changeover switch 4 contacts the contact 4b or 4c.

  The positive power supply terminal 6 </ b> P of the low VHF band voltage amplifier 6 is connected to a contact 10 b of the changeover switch 10 that is linked to the changeover switch 4. A contact 10a connected to a positive DC power source + V can come into contact with the contact 10b. The changeover switch 10 also has a contact 10c, which is an empty contact. Therefore, when the contact 10a is in contact with the contact 10b, a voltage of + V is supplied to the positive power supply terminal 6P of the low VHF band voltage amplifier 6, and when the contact 10a is in contact with the empty contact 10c, The + V voltage is not supplied to the positive power supply terminal 6P of the low VHF band voltage amplifier 6. The negative power supply terminal 6N of the low VHF band voltage amplifier 6 is connected to the ground potential.

  The changeover switches 4 and 10 constitute changeover means, which are interlocked. When the contact 4a of the changeover switch 4 is in contact with the contact 4b, the contact 10a of the changeover switch 10 comes into contact with the contact 10b. When the contact 4a of the changeover switch 4 is in contact with the contact 4c, the contact 10a of the changeover switch 10 is in contact with the contact 10c.

  The output of the low VHF band voltage amplifier 6 is supplied to variable attenuation means, for example, the input terminal 12IN of the PIN attenuator 12. As shown in FIG. 2, a resistor 14 is connected between the input terminal 12IN and the ground potential. The cathode of the PIN diode 16 is connected to the input terminal 12IN, and the anode is connected to the power supply terminal 12P via the resistor 18. As shown in FIG. 1, a positive DC voltage of + Vcc is supplied to the power supply terminal 12P. The power supply terminal 12P is connected to the anode of the PIN diode 22 via the resistor 20, and the cathode is connected to the output terminal 12OUT. A resistor 24 is connected between the output terminal 12OUT and the ground potential. These resistors 14, 18, 20, and 24 are impedances when the low-VHF band voltage amplifier 6 is viewed from the input terminal 12 IN and the PIN attenuator 12 from the input terminal 12 IN when the PIN diodes 16 and 22 are conductive. The values are set so that the input impedance seen from the synthesizer described later from the output terminal 12OUT matches the output impedance at the output terminal 12OUT.

  The cathode of a PIN diode 26 is connected to the input terminal 12IN, and its anode is connected to the arm of the variable resistor 28. Similarly, the cathode of the PIN diode 30 is connected to the output terminal 12OUT, and the anode thereof is connected to the arm of the variable resistor 28. One end of the variable resistor 28 is connected to the ground potential, and the other end is connected to a control signal supply terminal, for example, a control voltage supply terminal 12C. The control voltage supply terminal 12c is connected to the contact 10b of the changeover switch 10 as shown in FIG. Therefore, when the contact 10a of the changeover switch 10 contacts the contact 10b, the voltage + Vcc is also supplied to the control voltage supply terminal 12c, and is supplied to the PIN diodes 26 and 30 by adjusting the arm of the variable resistor 28. Current is changed, its conduction state is changed, and the terrestrial analog television broadcast signal in the low VHF band supplied to the input terminal 12IN is attenuated and output from the output terminal 12OUT.

  The high VHF band terrestrial analog television broadcast signal demultiplexed by the duplexer 2 is also supplied to the high VHF band voltage amplifier 34 via the changeover switch 32 having the same configuration as the changeover switch 4. That is, the changeover switch 32 has a contact 32a and contacts 32b and 32c, the contact 32b is connected to the input side of the high VHF band voltage amplifier 34, and the contact 32c is grounded via the impedance matching resistor 36. ing. The power terminal 34P of the high VHF band voltage amplifier 34 is connected to a contact 38b of a changeover switch 38 similar to the changeover switch 10, its contact 38a is connected to + Vcc, and the contact 38c is an empty contact. The changeover switches 32 and 38 operate in the same manner as the changeover switches 4 and 10.

  The output side of the high VHF band voltage amplifier 34 is supplied to the input terminal 40IN of the PIN attenuator 40 having the same configuration as the PIN attenuator 12. The PIN attenuator 40 has a power supply terminal 40P, a control voltage supply terminal 40C, and an output terminal 40OUT. The power supply terminal 40P is connected to + Vcc, and the control voltage supply terminal 40C is connected to a contact 38b of the changeover switch 38. Yes.

  The outputs generated at the output terminals 12OUT and 40OUT of the PIN attenuators 12 and 40 are combined by a combiner 42, input to a final stage amplifying means, for example, a power amplifier 44, and amplified and output here. The positive power supply terminal 44 </ b> P of the power amplifier 44 is connected to the cathodes of the diodes 46 and 48. The anode of the diode 46 is connected to the contact 10 b of the changeover switch 10, and the anode of the diode 48 is connected to the contact 38 b of the changeover switch 38. The negative power supply terminal 44N of the power amplifier 44 is connected to the ground potential. Therefore, the low VHF band voltage amplifier 6 or the high VHF band voltage is determined depending on whether the contact 10a of the changeover switch 10 is in contact with the contact 10b or the contact 38a of the changeover switch 38 is in contact with the contact 38b. As long as any of the amplifiers 34 is operating, the power amplifier 44 is operating.

  In the booster configured as described above, in the state where the terrestrial analog television broadcast is performed in the low VHF band and the high VHF band, the booster is broadcast in the low VHF terrestrial analog television broadcast signal and a frequency band in the vicinity thereof. In order to amplify the FM radio broadcast signal, the contacts 4a and 10a of the changeover switches 4 and 10 are brought into contact with the contacts 4b and 10b. Thus, a voltage of + Vcc is supplied to the low VHF band voltage amplifier 6, and the low VHF band terrestrial analog television broadcast signal and FM radio broadcast signal are supplied from the duplexer 2 to the low VHF band voltage amplifier 6. The low VHF band terrestrial analog television broadcast signal and the FM radio broadcast signal are amplified by the low VHF band voltage amplifier 6. At this time, since the control voltage is simultaneously supplied from the contact point 10b of the changeover switch 10 to the control voltage supply terminal 12C of the PIN attenuator 12, by operating the arm of the variable resistor 28 shown in FIG. The low VHF band terrestrial analog television broadcast signal and FM radio broadcast signal amplified and output from the voltage amplifier 6 are attenuated to a desired attenuation.

  In order to amplify the terrestrial analog television broadcast signal in the high VHF band, the contacts 32a and 38a of the changeover switches 32 and 38 are brought into contact with the contacts 32b and 38b. As a result, a voltage of + Vcc is supplied to the high VHF band voltage amplifier 34, a high VHF band terrestrial analog television broadcast signal is supplied from the duplexer 2 to the high VHF band voltage amplifier 34, and a high VHF band terrestrial broadcasting signal is supplied. The analog television broadcast signal is amplified by the high VHF band voltage amplifier 34. At this time, since the control voltage is simultaneously supplied from the contact 38b of the changeover switch 38 to the control voltage supply terminal 40C of the PIN attenuator 40, the variable resistor in the PIN attenuator 40 corresponding to the variable resistor 28 shown in FIG. By operating the arm of the device, the high VHF band terrestrial analog television broadcast signal amplified and output from the high VHF band voltage amplifier 34 is attenuated to a desired attenuation amount.

  Outputs from these PIN attenuators 12 and 40 are combined by a combiner 42 and supplied to a power amplifier 44. At this time, a voltage of + Vcc is supplied to the positive power supply terminal 44P of the power amplifier 44 via the contacts 10b and 38b of the changeover switches 10 and 38 via the diodes 46 and 48, and the power amplifier 44 is operating. .

  For example, when the terrestrial analog television broadcast is finished and the amplification of the low VHF band FM radio broadcast signal is continued, but the amplification of the terrestrial analog television broadcast signal of the high VHF band is stopped, the contact 32a of the changeover switch 32 is set. The contact 38a of the changeover switch 38 is switched to the contact 38c side on the contact 32c side. By switching the switch 32 to the contact 32c side of the contact 32a, the high VHF band high-frequency signal from the duplexer 2 is grounded via the impedance matching resistor 36, and the high VHF band voltage amplifier 34 Not supplied. Further, by switching the contact 38a of the changeover switch 38 to the contact 38c side, the + Vcc voltage is not supplied to the positive power supply terminal 34P of the high VHF band voltage amplifier 34, and the high VHF band voltage amplifier 34 does not operate. Further, the supply of + Vcc to the control voltage terminal 40C of the PIN attenuator 40 is also stopped. However, since the + Vcc voltage is continuously supplied to the positive power supply terminal 40P of the same attenuator 40 as the PIN attenuator 12, the PIN diode of the PIN attenuator 40 corresponding to the PIN diodes 16 and 22 shown in FIG. is doing. Therefore, the output impedance when the synthesizer 42 is viewed from the output terminal 40OUT of the PIN attenuator 40 matches the input impedance of the synthesizer 42, and impedance mismatch due to the high VHF band voltage amplifier 34 not operating. There is no problem.

  At this time, a voltage of + Vcc is supplied to the positive power supply terminal 44P of the power amplifier 44 from the contact 10b of the changeover switch 10 via the diode 46, and the power amplifier 44 is operating normally.

  When the amplification in the low VHF band is stopped and the amplification in the high VHF band is continued, the contact 4a of the changeover switches 4 and 10 is switched to the contact 4c, the contact 10a is switched to the contact 10c side, the changeover switch 32, 38, the contact 32a is switched to the contact 32b, and the contact 38a is switched to the contact 38b.

  When amplification in both the low VHF band and the high VHF band is not required, the contacts 4a and 10a of the changeover switches 4 and 10 are switched to the contacts 4c and 10c side, and the contacts 32a of the changeover switches 32 and 38 are switched. 38a is switched to the contacts 32c and 38c side. At this time, the supply of + Vcc to the power amplifier 44 is also stopped, so that useless power consumption does not occur.

  Although not shown in the figure, this booster is provided with an amplifying unit for amplifying UHF band terrestrial digital and analog television broadcast signals and an amplifying unit for amplifying intermediate frequency signals for satellite broadcasting and satellite communication. Are combined with the output of the power amplifier 44 and output.

  In the above embodiment, for example, when only FM radio broadcast signals are received in the low VHF band, filter means for extracting the FM radio broadcast signals to the output side of the low VHF band of the duplexer 2, such as a bandpass filter, is provided. It can also be configured to be inserted by operating the changeover switch.

  In the above embodiment, the high-frequency amplifier according to the present invention is used as an amplifier interposed in the line of the joint reception system. However, the present invention is not limited to this. For example, a television broadcast signal received by a television broadcast receiving antenna is used. It can also be used as a booster that amplifies and supplies it to a television receiver.

  In the above embodiment, both the voltage amplifier 6 for the low VHF band and the voltage amplifier 34 for the high VHF band are configured to be in the voltage supply state and the voltage cutoff state. It is also possible to use only one of the voltage amplifiers 34 for the high VHF band, for example. In that case, the selector switches 4 and 10 are removed, and the high frequency signal in the low VHF band of the duplexer 2 is supplied to the input side of the voltage amplifier 6 for the low VHF band as it is, and the positive power supply terminal 6P and PIN attenuation of the voltage amplifier 6 are supplied. The voltage of + Vcc is directly supplied to the control voltage supply terminal 12C of the device 12.

  In the above embodiment, the frequency band to be amplified by the high-frequency amplifier is the low VHF band and the high VHF band. However, the frequency band is not limited to this, and may be, for example, the VHF band and the UHF band. In this case, the voltage is supplied to and cut off from the power supply terminal of the voltage amplifier that amplifies the VHF band and the control voltage supply terminal of the PIN attenuator associated with the voltage amplifier.

  In the above-described embodiment, the PIN attenuator is used. However, the present invention is not limited to this, and various types can be used as long as the amount of attenuation can be varied by a control signal.

It is a block diagram of the high frequency amplifier of one Embodiment of this invention. FIG. 2 is a circuit diagram of a PIN attenuator used in the high frequency amplifier of FIG. 1.

Explanation of symbols

4 Changeover switch (switching means)
6 Low VHF band voltage amplifier (front amplifier)
10 Changeover switch (switching means)
12 PIN attenuator (variable attenuation means)
32 changeover switch (switching means)
34 High VHF band voltage amplifier (front amplifier)
38 selector switch (switching means)
40 PIN attenuator (variable attenuation means)
44 Power amplifier (final amplification means)

Claims (3)

A plurality of pre-amplifying means for amplifying high-frequency signals of different frequency bands,
Amplifying and outputting the output signal supplied from these pre-stage amplifying means, one final stage amplifying means to which power is continuously supplied,
Provided between the output side of at least a selected one of the preceding stage amplifying means and the input side of the final stage amplifying means, changing the attenuation amount according to the supplied control signal, and not supplying the control signal Variable attenuating means sometimes impedance matched with the final stage amplifying means;
Switching means for not supplying power to the selected pre-amplifying means and also for not supplying the control signal to the variable attenuation means;
A high-frequency amplifier provided. A plurality of pre-amplifying means for amplifying high-frequency signals of different frequency bands,
Amplifying and outputting the output signal supplied from these pre-stage amplifying means, one final stage amplifying means to which power is continuously supplied,
A plurality of switching means provided corresponding to each of the preceding amplification means, and switching to one of supply and cutoff states of the operating power supply to the corresponding preceding amplification means,
A high-frequency amplifier provided. 3. The high frequency amplifier according to claim 2, wherein variable attenuating means are provided between the output side of each preceding stage amplifying means and the input side of said final stage amplifying means, and these variable attenuating means are connected to the supplied control signal. Accordingly, the amount of attenuation is changed, and impedance matching is performed with the final stage amplifying means when the control signal is not supplied. Each variable attenuation means corresponds to each switching means, and the corresponding switching means is in the power-off state. A high-frequency amplifier in which the control signal is not supplied.

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