JP2006041967A - Filter device, amplifying device and television receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that not only an analog broadcasting wave signal but also such a signal whose electric field strength is large from the same direction as a terrestrial digital broadcasting signal is inputted to an amplifying device for television reception, thereby the input level of the amplifying device is increased, and any disturbance is generated on a reception screen. <P>SOLUTION: This filter device is provided with a first transmission path for passing a specific signal and a second transmission path for passing a signal which does not pass through the transmission path and first and second branching means between an input terminal and an output terminal. The first transmission path is interposed between the output terminal of the first branching means and the input terminal of the second branching means, and the specific signal is made to pass from the input terminal to the output terminal. The second transmission path is interposed between the branch terminal of the first branching means and the branch terminal of the second branching means, and any signal other than the specific signal is made to pass from the input terminal to the output terminal. This amplifying device is provided with the filter device and this receiving system is provided with those devices. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a filter device mainly used in a television receiving system, and more particularly to the filter device or an amplifying device including the filter device, and a television receiving system using these devices.

Conventionally, for example, when receiving a signal of 506 to 512 MHz in the UHF band, which is a specific signal, and an adjacent pass frequency band of 560 MHz or more, a passband filter (hereinafter referred to as a passband filter having a signal of 506 to 512 MHz as a passband) And a high-pass filter (hereinafter referred to as HPF) that uses a signal of 560 MHz or higher as a pass band. (For example, see Patent Document 1)
If there is a signal in a frequency band lower than a specific signal as well as the signal of 560 MHz or higher, it is mixed with a band-emission filter (hereinafter referred to as BEP) that allows signals other than the specific signal to pass. It was common to construct a filter device.

Japanese Utility Model Publication No. 63-1457

However, in recent years, digital terrestrial broadcasting has started in the area where specific signals of conventional analog broadcasting are received, and the transmitting antenna is set in the same direction or in the same direction as the transmission tower of terrestrial analog broadcasting. Simultaneous broadcasting with digital broadcasting will be performed. As a result, the terrestrial analog broadcast as a specific signal and the terrestrial digital broadcast using a frequency band close to the specific signal arrive from the same direction, and the number of reception channels increases.
Further, in terrestrial digital broadcasting, in order to cover a wide service area beyond conventional regional broadcasting, a transmission tower for transmitting the broadcast signal is used for signals of conventional terrestrial analog broadcasting intended for regional broadcasting. Therefore, in areas where terrestrial analog broadcasting, which is the specific signal, was received, the power of terrestrial digital broadcasting is the same as that of conventional terrestrial analog broadcasting signals. It becomes stronger than that. In the future, terrestrial analog broadcasting will be terminated.

In transmitting such signals, according to the conventional filter device, a filter device is provided that allows a specific signal frequency band to pass through with low loss and a frequency band other than the specific signal to pass through with low loss. However, for example, even when it is necessary to adjust the level of a frequency band other than a specific signal to pass through, the level cannot be adjusted.

In addition, a system for receiving a specific signal of terrestrial analog broadcasting, for example, a television reception amplifier for receiving the specific signal in an area where the incoming radio wave is weak, such as a shade of a mountain or a shade of a building. In a television receiving system in which a device is installed, not only the conventional terrestrial analog broadcast wave signal but also a multi-channel terrestrial digital broadcast signal is newly input to the television receiving amplification device. In a conventional television reception system equipped with a filter device, when the input level of the television reception amplifying device is increased, the signal amplified by the television reception amplification device is distorted and the reception screen is disturbed. The problem mentioned above may occur.
As a countermeasure, for example, a method of connecting a filter device consisting of a band-pass filter that passes only a specific signal of terrestrial analog broadcasting can be considered, but if you want to change from terrestrial analog broadcasting to terrestrial digital broadcasting, There was a problem that the digital terrestrial broadcasting could not be watched unless the filter was changed again when the broadcast ended.
Therefore, the present invention has been made to solve these problems,
An object of the present invention is to provide a filter device that allows a frequency band of a specific signal to pass through with low loss and allows a frequency band other than the specific signal to pass through at a predetermined level.
Another object is a filter device that allows a frequency band of a signal arriving from the same direction to pass through a specific signal frequency band with low loss, and allows a frequency band other than the specific signal to pass through with a predetermined amount lowered. Is to provide.
It is an object of the present invention to provide a filter device that facilitates adjustment of a transmission path through which a specific signal passes and a transmission path through which a signal excluding the specific signal passes.
An object is to provide a highly versatile filter device for a combination of a specific signal and a signal excluding the specific signal.
Another object of the present invention is to provide an amplifying apparatus for receiving a television with a built-in filter device that allows a specific signal frequency band to pass through with low loss and allows a frequency band other than the specific signal to pass through at a predetermined level. There is.
Another object of the present invention is to provide a television receiving system having a simple configuration that allows a specific signal frequency band to pass through with low loss and allows a frequency band other than the specific signal to pass through at a predetermined level.

In order to solve the above-mentioned problems, the invention according to claim 1 is the filter device, wherein the filter device has an input terminal and an output terminal, and the first branching means and a specific part are provided between the input terminal and the output terminal. A first transmission path having filter means for passing a signal; a second transmission path for passing a signal in a predetermined range including the specific signal; and a second branching means. The transmission path is interposed between the output end of the first branching means and the input end of the second branching means to allow a specific signal to pass from the input terminal to the output terminal, and for the second transmission. The line is interposed between the branch end of the first branch means and the branch end of the second branch means so as to pass a signal in a predetermined range including the specific signal from the input terminal to the output terminal. Composed.

According to a second aspect of the present invention, the second transmission path includes filter means for passing a signal that does not pass through the filter means of the first transmission path, and signals other than the specific signal are output from an input terminal to an output terminal. Configured to pass through.

According to a third aspect of the present invention, in the filter device according to the first or second aspect, at least one of the first transmission path and the second transmission path is configured as a unit. The filter device can be detachably fixed.

According to a fourth aspect of the present invention, there is provided a television reception amplifying device including the filter device according to any one of the first to third aspects.

According to a fifth aspect of the present invention, a television receiving system is configured by using the filter device according to any one of the first to third aspects or the television receiving amplifying device according to the fourth aspect.

As described in detail above, according to the first aspect of the present invention, in the filter device, the filter device has an input terminal and an output terminal, and the first branch means is provided between the input terminal and the output terminal. A first transmission path comprising filter means for passing a specific signal; a second transmission path for passing a signal in a predetermined range including the specific signal; and a second branching means, The first transmission path is interposed between the output terminal of the first branching unit and the input terminal of the second branching unit, and allows a specific signal to pass from the input terminal to the output terminal. The transmission line is interposed between the branch end of the first branch means and the branch end of the second branch means, and allows a signal in a predetermined range including the specific signal to pass from the input terminal to the output terminal. Because it was configured as
The first transmission path and the second transmission path do not interfere with each other due to the reverse coupling of the branch circuit, can be adjusted easily, and thus can deliver products faster. At the same time, product costs can be reduced.
Furthermore, a specific signal frequency band is allowed to pass with low loss, and a signal in a predetermined frequency band including the specific signal is allowed to pass through with an appropriate level adjustment by setting the branch amount of the branch circuit to a predetermined level. Therefore, it is possible to provide a filter device that can make the signal level within a predetermined range including the specific signal uniform, lower, or relatively change with respect to the specific signal.

According to a second aspect of the present invention, the second transmission path includes filter means for passing a signal that does not pass through the filter means of the first transmission path, and signals other than the specific signal are input from an input terminal. Since it is configured to pass through the output terminal,
The first transmission path and the second transmission path do not interfere with each other due to the reverse coupling of the branch circuit, and can be adjusted easily, so that the product can be delivered quickly. Therefore, the product cost can be reduced.
Furthermore, the frequency band of a specific signal is allowed to pass with low loss, and the signal of a frequency band other than the specific signal can be allowed to pass with a reduced level as appropriate by setting the branch amount of the branch circuit to a predetermined level. Therefore, it is possible to provide a filter device that can align or lower the signal level other than the specific signal, or can relatively vary the specific signal.

According to a third aspect of the present invention, in the filter device according to the first or second aspect, at least one of the first transmission path and the second transmission path is configured as a unit. Since it is configured to be detachably fixed from the filter device,
For example, in a region where this filter device is used, even if a specific signal and a signal other than a specific signal are different from each other, a unitized transmission path is prepared so that it can basically handle each signal as necessary. It is not necessary to prepare various types of filter devices so that they can be adapted to all regions, and it is possible to provide a filter device that can respond quickly to demand.

According to a fourth aspect of the present invention, since the filter device according to any one of the first to third aspects is provided to constitute a television receiving amplifying device,
A system for receiving a terrestrial analog broadcast that is a specific signal, and a television receiving amplifying device for receiving the specific signal in an area where an incoming radio wave is weak, such as a shadow of a mountain or a shadow of a building In the area where the system is installed, a new broadcast such as digital terrestrial broadcasting is started in the area where the system is installed, and the signal of the broadcast is close to the conventional analog terrestrial broadcast. Even if it is necessary to receive a signal that is in the same direction as the terrestrial analog broadcast radio wave and has a higher level than the terrestrial analog broadcast signal, the conventional terrestrial analog broadcast wave signal is Digital terrestrial broadcasting signals with as little passage loss as possible, with high electric field strength and high wave number, are amplified for television reception by the amount of coupling of branching means. Since the input level of the television receiving amplifying device is optimized by being adjusted and input so that the input level is less than the maximum input level to the device, the signal amplified by the television receiving amplifying device is distorted and received. The problem that the screen is disturbed can be eliminated.

According to the invention of claim 5, since the television receiving system is configured using the filter device according to any one of claims 1 to 3 or the television receiving amplifying device according to claim 4,
A system for receiving a terrestrial analog broadcast that is a specific signal, and a television receiving amplifying device for receiving the specific signal in an area where an incoming radio wave is weak, such as a shadow of a mountain or a shadow of a building In the area where the system is installed, a new broadcast such as digital terrestrial broadcasting is started in the area where the system is installed, and the signal of the broadcast is close to the conventional analog terrestrial broadcast. Even if it is necessary to receive a signal that is in the same direction as the terrestrial analog broadcast radio wave and has a higher level than the terrestrial analog broadcast signal, the conventional terrestrial analog broadcast wave signal is Digital terrestrial broadcasting signals with as little passage loss as possible, with high electric field strength and high wave number, are amplified for television reception by the amount of coupling of branching means. By being adjusted to be below the maximum input level to the location input, it said that the input level of the television signal receiving amplifier is optimized, it is possible to provide a television receiving systems without disturbing the television picture.

Hereinafter, an example of an embodiment embodying the present invention will be described in detail with reference to the drawings. 1A is a block diagram showing an embodiment of the filter device according to the present invention, FIG. 1B is a block diagram showing a different embodiment of the filter device according to the present invention, and FIG. 2 is a filter shown in FIG. A specific configuration example of the apparatus will be shown. FIG. 3 shows the frequency characteristics of the filter device according to the present invention. FIG. 4 is a block diagram of the television receiving amplifier according to the present invention. FIG. 5 shows a television receiving system using the filter device according to the present invention. FIG. 6 is a block diagram showing a second embodiment of the filter device according to the present invention.

In FIG. 1A, 3 is a filter device according to an embodiment of the present invention, 3a is an input terminal, and 3b is an output terminal.
The input terminal 3a is arranged so that the input terminal of the branching means 10a (indicated as Input in the figure, hereinafter referred to as Input) is connected to the output terminal 3b, and the input of the branching means 10b is connected to the output terminal 3b. . Further, a filter having a specific signal 30a as a pass band between the output terminal of the branch circuit 10a (indicated as “Output” in the figure, hereinafter referred to as “Output”) and the output of the branch circuit 10b. A first transmission path composed of means (for example, a band pass filter (BPF)) 31 is connected.
Further, a signal other than the specific signal shown in 30b passes between the branch output of the branch circuit 10a (indicated as Br in the figure, hereinafter referred to as Br) and the Br of the branch circuit 10b. A second transmission path composed of filter means (for example, a band illumination filter (BEP)) 33 configured to be connected is connected.
In the embodiment of the present invention, the branching means 10a and 10b are constituted by a branch circuit in which a coil is wound around a ferrite.

Next, the operation of this filter device will be specifically described with reference to FIGS. For example, the UHF band ch19 having a low signal level as the specific signal and the UHF band ch13 to 17 and ch24 and the like having a strong signal level other than the specific signal are input to the input terminal 3a. (Hereafter, UHF band is omitted)
After passing through the branching means 10a, ch19 passes through the first transmission path 30a composed of the BPF 31 having this channel as a pass band. Further, after passing through the first transmission path 30a, it is output to the output terminal 3b via the branching means 30b.

Next, the second transmission path 30b will be described. Signals of ch 13 to 17 and ch 24 or more (so-called signals other than specific signals) inputted to the input terminal 3a are inputted to the filter means 33 from the branch terminal of the branch means 10a. The signal at this time is attenuated by the coupling amount of the branching means 10a. After passing through the second transmission path 30b, the signal is output from the output terminal 30b via the branch means 10b branch terminal.
The filter means 33 is composed of, for example, BEF, and is a filter that blocks the specific signal and passes the channels 13 to 17 and ch24 or more that are signals other than the signal.

In this way, the signals of ch13 to ch17 and ch24 or more that have been lowered in level corresponding to the amount of coupling between the ch19 that has passed through the first transmission path 30a and the branching means 10a and that have passed through the second transmission path 30b are Further, the signals are combined with each other in the branching means 10b. At this time, the signals passing through the second transmission path are further lowered in level by the coupling amount of the branching means and output to the output terminal 3b.
As a result, for example, when transmitting ch19 which is a specific signal having a low level and signals other than the specific signal having a high level which are ch13 to ch17 and ch24 or higher, ch13 to ch17 and Since it is possible to provide a filter device capable of transmitting a signal of ch24 or higher so that the level can be adjusted to a specific signal level (in this case, ch19) or lower than the specific signal level by the branching means 10a and 10b. is there.
FIG. 2 shows a specific embodiment of the filter means 31 and 33, where C1 to C6 are capacitors and L1 to L6 are coils.

FIG. 3 shows the frequency characteristics of the filter device 3 of the above embodiment. In this figure, 11 indicates the frequency characteristic of the first transmission path 30a, and 12 indicates the frequency characteristic of the second transmission path 30b.
As described above, according to the filter device 3 of the present invention, the BPF 31 that constitutes the first transmission path 30a and the BEP 33 that constitutes the second transmission path 30b have the reverse coupling characteristics of the branching means 10a and 10b. Therefore, it is possible to provide a filter device that can be easily adjusted and has good characteristics.
In the embodiment of the present invention, the filter means 31 of the first transmission path 30a is made of BPF, and the filter means 33 of the second transmission path is made of BEP. 33 is not particularly limited to this embodiment, such as a trap circuit.

Next, different embodiments of the filter device 3 of the present invention will be described. It should be noted that the same components as those in the embodiment shown in FIG.
In the above embodiment, the filter means 31 and 33 are disposed on the same main body substrate as the branching means 10a and 10b. However, as shown in FIG. BPF) 31 is unitized and configured as a separate substrate from the main body substrate. The filter unit 31 is provided with connection terminals on the input side and the connection side, and on the main body substrate side, a connection terminal corresponding to the connection terminal is provided at a position facing the connection terminal. The filter unit 31 is detachably fixed.
According to this embodiment, in order to pass a specific signal having a narrow and limited band, it is necessary to produce several types of BPF 31 that need to be very difficult to adjust in advance according to the area where it is considered necessary. In addition, the filter means that has been adjusted individually and allows signals other than specific signals to pass through must be adjusted individually on the main board to produce as many main boards as the number of filters. This makes it possible to streamline production and, in turn, reduce product costs.
In this embodiment, the filter unit 31 is unitized. However, the filter unit 33 may be unitized, and the present invention is not limited to the example.
Further, as in the embodiment shown in FIG. 4, the television receiver amplifier 40 may be configured by disposing the filter device 3 according to the present invention and the amplifier circuits 40a and 40b. The configuration of the amplifier circuit is for showing the embodiment and is not limited to this embodiment.

Next, a television receiving system shown in FIG. 103 provided with the filter device will be described with reference to FIG. In FIG. 5, 101 is a conventional UHF band transmission tower for analog broadcasting, and 102 is a newly installed UHF band transmission tower for terrestrial digital broadcasting.
Reference numeral 1 denotes a VHF antenna which is input to the VHF input terminal 1a of the television receiving amplifier 4 through the transmission line 2a. Reference numeral 6 denotes a UHF antenna, which is input to the UHF input terminal 6a of the television receiving amplifier 4 through the transmission line 2b and the filter device 3 of the present invention.

Each signal input to the television receiving amplifying device 4 is amplified to a predetermined level, mixed and then output. The output signal is connected to the television receiver 9 via the transmission line 2c, distributor 5, transmission line 2d, television terminal 7a, transmission line 2e, and power supply device 8.

Next, the television receiving system 103 will be specifically described. The transmission tower 101 is a transmission tower for terrestrial analog broadcasting and performs regional broadcasting using the UHF band. The television receiving system of the present invention is for receiving the analog broadcast in an area where the reception electric field strength is weak such as an area a little away from the service area of the terrestrial analog broadcast or an area behind a mountain or a building. System.
For example, UHF band ch 19 is transmitted from the terrestrial analog broadcast transmission tower 101. In order to receive this signal, in a region that is not the original service area as described above, or in a weak electric field region such as Sanin, a TV reception amplifying device 4 is installed to receive the target analog broadcast. ing. After the radio wave is received by the UHF receiving antenna 6, it is input to the amplifying device from the UHF input terminal 6 a of the television receiving amplifying device 4 through the transmission line 2 b, is appropriately amplified, and then connected to the television receiver 9. Yes.

However, as shown by 102 in FIG. 1, a broadcast wave such as terrestrial digital broadcasting using a frequency band close to the frequency band of analog terrestrial broadcasting is newly transmitted from the same direction or the same transmission tower. In this case, in addition to the terrestrial analog broadcast signal, the number of channels for the terrestrial digital broadcast signal increases. Further, in order to enable service to a wide area, which is a feature of terrestrial digital broadcasting, the terrestrial digital broadcasting transmission tower 102 may be installed higher than the height of the terrestrial analog broadcasting transmission tower 101. The signal level of terrestrial digital broadcasting is stronger than that of analog terrestrial broadcasting.

Such terrestrial analog broadcast signals and terrestrial digital broadcast signals are received by the UHF television antenna 6 and input to the input terminal 3a of the filter device 3 via the transmission line 2b.
Among the input signals, a terrestrial analog broadcast signal (for example, ch19 in the embodiment of the present invention) which is a specific signal passes through the BPF 31 of the first transmission path 30a.
In addition, terrestrial digital broadcast signals (for example, ch13 to 17 and ch24 in the embodiment of the present invention) that are signals other than the specific signal pass through the BEF 33 of the second transmission path 30b. The second transmission path 30b in the embodiment of the present invention is an adjacent channel that is a terrestrial digital broadcast signal that interferes with the specific signal in order to receive the terrestrial analog broadcast ch 19 that is a specific signal. The ch 18 is configured not to pass through.
The signals passing through the first signal path 30a and the second signal path 30b are combined and output from the output terminal 3b. The output signal is input from the UHF input terminal 6a of the television receiving amplifier 4 to the amplifier. At this time, depending on the input level of a signal added later, for example, the signal of terrestrial digital broadcasting, the television receiving amplifying device 4 may be over-input, and the received image may be disturbed.

In terms of experimentally obtained numerical values, when the terrestrial digital broadcast signal is about +10 dB higher than the terrestrial analog broadcast signal, a gain adjustment circuit (shown in FIG. If the terrestrial digital broadcast signal is higher than +10 dB, the terrestrial digital broadcast signal is set to an appropriate level in addition to the response by the television receiving amplifying device 4. If the level is not adjusted, the received image will be disturbed.
According to the television receiving system 103 including the filter device 3 of the present invention, the first signal path 30a that allows the analog broadcast ch 19 that is a specific signal to pass through, and the terrestrial digital broadcast that is a signal other than the specific signal. The second transmission path 30b that passes through the channels 13 to 17 and ch24 is connected in parallel via the branch means 10a and 10b, and the second transmission path 30b is connected to the branch terminals of the branch means 10a and 10b. Since the terrestrial digital broadcasting signal is too high as described above, the level of signals other than the specific signal is attenuated by a predetermined level by the coupling amount of the branching means 10a and 10b. Therefore, it is possible to prevent the input over of the television receiving amplifier 4 from being exceeded.

Furthermore, a new terrestrial digital broadcasting as described above is started, so that in the area where the interference by the terrestrial digital broadcasting has occurred, a ch19 dedicated bandpass filter is installed on the transmission line in order to view the conventional terrestrial analog broadcast ch19. Compared with the case where measures are taken, the measure with the dedicated band-pass filter needs to be refurbished when it is desired to receive digital terrestrial broadcasting, whereas the filter device 3 of the present invention is used. Therefore, it is possible to provide versatility that can be changed to reception of digital terrestrial broadcasts at any time (excluding adjacent channels of terrestrial analog broadcasts; ch18 in the example of the present invention).
Further, by unitizing the filter means as in the embodiment of the present invention, it is only necessary to prepare several kinds of filter means based on the channel arrangement in the area where such a receiving system is required, thereby streamlining productivity. And product costs can be reduced.
In the present invention, the first transmission path 30a has a UHF band as a specific signal as a pass band, and the second transmission path 30b has a UHF band as a signal other than the specific signal as a pass band, As typical examples, the specific signal is ch19 of analog broadcasting, and the signals other than the specific signal are ch13 to ch17 and ch24 signals of digital terrestrial broadcasting. However, the present invention is not limited to these, and the frequency band to be used is not limited thereto. Needless to say, the signal content may be changed to an optimum one as appropriate. Further, the filter means is not limited to the above embodiment as long as the filter means is configured to pass a necessary signal.
Further, as shown in FIGS. 6 (a) and 6 (b), the second transmission path is a through circuit so that signals within a predetermined range including the specific signal are attenuated by the coupling amount of the branching means 10a and 10b. For example, the configuration of each unit may be changed as appropriate without departing from the spirit of the present invention.

(A) is a block diagram showing an embodiment of the filter device according to the present invention, and (B) is a block diagram showing a different embodiment of the filter device according to the present invention. 2 is a specific configuration example of the filter device shown in FIG. It is an example of the frequency characteristic of the filter apparatus which concerns on this invention. 1 is a block diagram of a television reception amplifying device according to the present invention. FIG. It is a television receiving system using the filter device of the present invention. It is a block diagram which shows 2nd Embodiment of the filter apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... VHF television antenna, 1a ... VHF input terminal, 2a * 2b * 2c * 2d * 2e ... transmission line, 3 ... filter apparatus, 3a ... input terminal, 3b ... output terminal, 4.40 ... amplifier for TV reception, 40a, 40b ... amplifier circuit, 5 ... distributor, 6 ... UHF TV antenna, 6a ... UHF input terminal, 7a, 7b, 7c, 7d ... TV terminal, 8 ... power supply, 9 ... TV receiver, 10 ... branching means , 11 ... frequency characteristics of the first transmission line, 12 ... frequency characteristics of the second transmission path, 30a ... first transmission line, 30b ... second transmission line, 31 ... bandpass filter (BPF), 31a ... Connection terminal, 31 connection terminal, 33... Band elmination filter (BEF), 101... Analog broadcast transmission tower, 102. Terrestrial digital broadcast transmission tower, 103.

Claims (5)

In the filter device,
A first transmission path having an input terminal and an output terminal, and having a first branching means and a filter means for allowing a specific signal to pass between the input terminal and the output terminal;
A second transmission path through which a predetermined range of signals including the specific signal pass;
A second branching means,
The first transmission path is interposed between the output terminal of the first branching unit and the input terminal of the second branching unit, and passes a specific signal from the input terminal to the output terminal.
The second transmission line is interposed between a branch end of the first branch means and a branch end of the second branch means, and a signal within a predetermined range including the specific signal is output from an input terminal to an output terminal. A filter device characterized by being configured to pass through.
The second transmission path includes filter means for passing a signal that does not pass through the filter means of the first transmission path, and is configured to pass signals other than the specific signal from the input terminal to the output terminal. The filter device according to claim 1.
The first transmission path or the second transmission path is configured by unitizing at least one of the first transmission path and the second transmission path, and is configured to be detachably fixed from the filter device. Item 3. The filter device according to Item 2.
A television receiving amplifying device comprising the filter device according to any one of claims 1 to 3.
A television receiving system using the filter device according to any one of claims 1 to 3 or the television receiving amplifying device according to claim 4.

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