JPH0654311U - Relay amplifier - Google Patents

Abstract

(57) [Abstract] [Purpose] In a conventional relay amplifier device, an unnecessary signal is inevitably amplified due to its structure, so that it interferes with other communications and increases the load on the amplifier circuit. Prevent this. [Structure] A distributor for distributing an input frequency band into n frequency bands and a converter for converting each of the distributed n frequency bands into an intermediate frequency separately and using a narrow band filter to separate adjacent signals other than the center frequency from each other. A frequency selection circuit composed of n circuits that return to the original n frequency bands and a synthesizer that synthesizes the n frequency bands into a transmission frequency band is provided in the preceding stage of the amplifier circuit. Prepared

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention mainly relates to a relay amplifying device used for mobile communication.

[0002]

[Prior art]

 FIG. 3 is a diagram showing a schematic configuration of a conventional device of this type, and FIG. 3 (a) is a relay amplification device for relaying bidirectionally between a base station and a mobile device, such as a car telephone, FIG. 3B shows a relay amplifying device that performs one-way relay, such as a radio paging device. In the figure, 1 is an antenna duplexer, 2 is an AMP (amplifying circuit), and 3 is a filter. Since communication frequencies or frequency bands are generally assigned to mobile phones and radio call devices, the assigned frequency or frequency band is selected using the antenna duplexer 1 or the filter 3 and the AMP2 is used. It is amplified and then transmitted to the mobile device.

[0003]

[Problems to be solved by the device]

 The conventional relay amplification device as described above has the following problems. FIG. 4 is a diagram for explaining the problems of the conventional relay amplifier device. For example, as shown in FIG. 4 (a), the input signal has frequency bands A, B, and C, and is used in a car telephone or the like. When the frequency band B is assigned, the bidirectional relay device shown in FIG. 3A selects the frequency band B using the antenna duplexer 1 and amplifies it. However, in the selection of the frequency band using the antenna duplexer 1 and the filter 3, the attenuation characteristic becomes a trapezoid as shown in FIG. 4 (b), and therefore, a part of the signals in the A and C bands on both sides of the B band. (Shaded area) also passes, and if there is an unnecessary signal in the B band, it is also amplified at the same time.

In addition, for example, among input signals as shown in FIG. 4 (c), in frequency allocation of a radio calling device, solid lines f1 to f5 are desired signals, and other broken line signals are unnecessary. If the signal is a desired signal, that is, if a desired signal and an unnecessary signal are mixed in the frequency band, the device using the antenna duplexer 1 or the filter 3 cannot select only the desired signal. . That is, only a desired signal needs to be selected with a narrow band filter as shown in FIG. 4D, but such a filter cannot be realized in reality. Therefore, unnecessary signals must be amplified at the same time.

As described above, the relay amplification device ideally relays and amplifies only the desired signal to be relayed, but the conventional device has no choice but to amplify the unnecessary signal, which causes other communication. There is a problem in that it causes interference, and a large AMP with a large saturated output is required because unnecessary signals must be amplified.

The present invention has been made to solve the above problems, and provides a relay amplification device that has an accurate frequency selection function, does not interfere with other communications, and can use a small AMP. Is intended.

[0007]

[Means for Solving the Problems]

 The relay amplification device according to the present invention comprises a distributor for distributing an input frequency band into n frequency bands and a center frequency with a narrow band filter for converting each of the distributed n frequency bands into an intermediate frequency. Frequency selection circuit composed of n circuits that remove adjacent signals other than the above and return to the original n frequency bands, and a combiner that combines the n frequency bands into a transmission frequency band It is characterized in that the input signal is converted into a signal including only the necessary signal by the frequency selection circuit, then amplified by the amplification circuit and relayed and amplified as the output signal.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. FIG. 1 (a) is a relay amplifying device used in, for example, a car telephone, which is a device for relaying bidirectionally between a base station and a mobile device. Reference numeral 1 (b) is a device that performs one-way relay, such as a relay amplification device used for a radio calling device. In the figure, 1 is an antenna duplexer, 2 is an AMP (amplification circuit), and 3 is a filter. Reference numeral 10 indicates a frequency selection circuit.

FIG. 2A is a block diagram showing an example of the frequency selection circuit shown in FIG. In this example, as shown in FIG. 2B, a case where five desired signals of frequencies f1 to f5 are selected from a large number of signals will be described as an example. In FIG. 2A, 11 is a distributor, 12 is a mixer, 13 is a local oscillator, 14 is a narrow band filter, 15 is a mixer, and 16 is a combiner. The distribution / combining number of the distributor 11 and the combiner 16 is 5, which is the number of signals to be selected. Further, a circuit including the mixers 12 and 15, the local oscillator 13, and the narrow band filter 14 is provided in five stages, which is the same as the number of signals to be selected. The operation will be described by taking as an example the case where five desired signals of frequencies f1 to f5 and other unnecessary signals as shown in FIG. 2B are input. An input signal including a desired signal of frequencies f1 to f5 and other unnecessary signals is divided into five by the divider 11, and each is input to the mixer, for example, the signal of output 1 is input to the mixer 12. Further, the local oscillator 13 supplies the signal of f _L 1 (f _L 1 = f1-fc) to the mixer 12 and the mixer 15, and therefore the signal of the frequency f1 is frequency-converted by the mixer 12 to the intermediate frequency of the frequency fc. Then, it is input to the narrow band filter 14 of the intermediate frequency fc, and the signal adjacent to the frequency fc is removed. The output of the narrow band filter 14 is input to the mixer 15, and the signal supplied from the local oscillator 13 in the mixer 15 causes the signal of the intermediate frequency fc to be frequency-converted to the frequency f1 and input to the input 1 of the synthesizer 16. To be done. In this way, only the desired signal f1 is selected. Note that although the output signal _{f L 1, f L 1 =} f1-fc of the local oscillator 13 and is operable also in signal f _L 1 = f1 + fc. Similarly, desired signals f2 to f5 are selected from the output signals of the outputs 2 to 5 of the distributor 11, and are input to the inputs 2 to 5 of the combiner 16. In this way, the output signal of the combiner 16 is only the desired signal of f1 to f5 as shown in FIG. 2 (C), and unnecessary signals are removed. This signal is amplified by AMP2.

That is, the frequency selection circuit 10 of the present embodiment removes adjacent signals by the narrow band filter 14 by setting the intermediate frequency fc sufficiently low with respect to the input frequencies f1 to fn. For example, when the signal frequency before frequency conversion is as high as 800 MHz, it is difficult to remove the adjacent signal (for example, ± 25 kHz) even by simply using a narrow band filter, but a low intermediate frequency (for example, 50 MHz). z), the adjacent signal (± 25 kHz) can be easily removed. Therefore, the frequency selection circuit 10 of the present embodiment converts the signal to a low intermediate frequency and then the adjacent signal by the narrow band filter. Is configured to be removed. In the embodiment shown in FIG. 2, the desired signals are set to f1 to f5 and five stages of circuits are used. However, no matter how many desired signals are used, it is sufficient to use as many circuits. Needless to say. Further, in the embodiment shown in FIG. 2, the intermediate frequencies of all stages are set to fc, but it is also possible to use significantly different intermediate frequencies. Further, the frequency selection circuit of FIG. 2 is merely an example, and the frequency selection circuit having the same function is not limited to the configuration of FIG.

[0011]

[Effect of device]

 As described above, according to the present invention, since the frequency selection circuit inserted in the preceding stage of the amplification circuit limits only the necessary signals and then amplifies the signals, there is no risk of unnecessary transmission and interference with other communications. Can be reduced. Also, since the load on the amplifier circuit can be lightened, it is possible to use a small amplifier circuit with a smaller saturated output than the conventional device, and when using the same amplifier circuit as the conventional one, increase the output signal level. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the configuration and operation of the frequency selection circuit shown in FIG.

FIG. 3 is a diagram showing a schematic configuration of a conventional device of this type.

FIG. 4 is a diagram for explaining a problem of a conventional device.

[Explanation of symbols]

 1 Antenna Duplexer 2 AMP 3 Filter 10 Frequency Selection Circuit 11 Divider 12 Mixer 13 Local Oscillator 14 Narrowband Filter 15 Mixer 16 Combiner

Claims (1)

[Scope of utility model registration request] 1. A relay amplifying device for relay-amplifying a signal of a desired frequency to be relayed from an input signal, wherein a distributor for distributing the input frequency band into n frequency bands and a distributed n frequency band are provided. These n frequency bands are combined with n circuits that individually convert to intermediate frequencies and remove adjacent signals other than the center frequency with a narrow band filter before returning to the original n frequency bands. Equipped with a frequency selection circuit composed of a synthesizer that uses the transmission frequency band as a transmission frequency band.The input signal is converted to a signal that contains only the necessary signals by this frequency selection circuit, then amplified by an amplification circuit and relayed as an output signal A relay amplifying device characterized by: