KR920004121B1 - Double converter - Google Patents

Abstract

The converter includes a first mixing means (45) for converting an amplified frequency to obtain medium frequency signals. A first medium frequency means (60) band-restricts and amplifies the output of the first mixing means (45), and a second mixing means (85) converts the frequency of the output of the first medium frequency means (60) to obtain second medium frequency signals. An amplifier (20) amplifies filtered signals, and a diplexer (30) selects one set of signals from among the output signals of the amplifier (20). The converter reduces the interference between the channels.

Description

Double converter

1 shows an overview of a double converter system according to the invention.

2 is an exploded perspective view of a double converter according to the present invention.

3 is a cross-sectional view of the double converter shown in FIG.

* Explanation of symbols for main parts of the drawings

10A: first band filter section 10B: second band filter section

20A: first RF amplifier 20B: second RF amplifier

30: diplexer 40: first local oscillator

45: first mixer 50: third band filter portion

60: first intermediate frequency amplifier 70: fourth band filter

80: second local oscillator 85: second mixer

90: second intermediate frequency amplifier

The present invention relates to a double converter for a TV using a double super heterodyne method, and more particularly, to employ an AGC capable amplifier while adopting a double tuner input filter in an up converter for amplifying an input RF signal. The present invention relates to a wideband double converter that can improve the gain of the up-converter and reduce noise.

Recently, a double super scheme having two local oscillators and two mixers has been devised as a reception scheme that enables reception of a wide frequency band over a wide bandwidth and eliminates tracking adjustment for each channel. This method is capable of receiving a wider band by selecting the first intermediate frequency higher than the upper limit of the reception frequency, and has an advantage of reducing the influence of interference waves. However, as the first intermediate frequency increases, assembly adjustment for circuit stability is required in the circuit design configuration. The designed double converter is described in U.S. Patent No. 4,214,212 and Japanese Laid-Open Patent Publication No. 60-66527, but they amplify the RF signal input to the RF input terminal in the RF amplifier circuit and adjust it at the appropriate level according to the signal level. As a result of supplying to the first mixer, signal interference occurs between the channels, the gain of the up-converter is reduced, and noise occurs.

Therefore, the present invention was created in view of the above-mentioned problems. As a result, a double tuner input filter is used for the up-converter and a double that can reduce the gain and noise of the converter by eliminating signal overlap between channels by using each amplifier capable of AGC. The main purpose is to provide a converter.

Another object of the present invention is to provide a double converter that facilitates assembly between the most difficult circuits from the circuit configuration, and facilitates adjustment between circuits and does not change the input / output of a high frequency signal.

In order to achieve the above object, the double converter according to the present invention comprises an up-converter and a down-converter. A double tuner input filter is connected to an input terminal of the up-converter and amplified at the same time. An AGC capable amplifier, a diplexer for selecting any one of signals output from the amplifier, and first mixing means.

On the other hand, the structure of the double converter according to the present invention is a double tuner input filter, an AGC capable amplifier, a diplexer and a first mixing means at the input terminal of the converter is formed of a partition wall and a micro strip line on one side of an independent PCB. The other side of the PCB is fixed in close contact with the conductive insulating chassis, and the insulating chassis is installed to be attached to and detached from the longitudinal direction of the wall to face the down converter.

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

1 shows a schematic diagram of a double converter according to the present invention, in which the first and second band filter units 10A and 10B are connected in parallel to the RF signal input terminal IN to connect the input RF signal to the VHF. And UHF bands. The first and second RF amplifiers 20A and 20B are connected in series to the first and second band filter units 10A and 10B, respectively, so that the filtered signal is appropriately level according to the signal level input by the AGC circuit. Configured to amplify. The diplexer 30 is commonly used as a transmission means. In the present system, the diplexer 30 is configured to diplex the output signals of the first and second RF amplifiers 20A and 20B to the first mixer 45. The above configuration describes the up-converter 100. On the other hand, the down converter 200 is the first intermediate frequency amplifier 60, the second local oscillator 80 and the second mixer 85 and the second intermediate frequency to amplify the output of the first mixer 45 by limiting the band It consists of an amplifier 90. Here, the second intermediate frequency amplifier 90 may stabilize the output characteristics by using a feedback amplifier, thereby eliminating the use of coils as in the prior art.

FIG. 2 is an exploded perspective view of the double converter, and FIG. 3 is a sectional view thereof, and the symbols in FIGS. 2 and 3 correspond to each other. In the same figure, the up-converter of this system is formed with a partition 3A and a microstrip line 4 on one side of an independent PCB 3, and the other side of the PCB 3 is fixed to the insulation chassis 5 in close contact. The insulated chassis 5 is installed in the walls 6A and 6B on which the PCB 2 having the downconverter is formed is installed to face each other, and the insulated chassis 5 is detachable from the walls 6A and 6B. On the other hand, the upper and lower covers 1A and 1B are formed on the upper and lower ends of the walls 6A and 6B.

The RF signal input to the RF input terminal IN of the double converter according to the present invention having the configuration as described above is first filtered after the VHF and UHF bands through the first and second band filter units 20A and 20B, respectively. 1 and 2 RF amplifiers 20A and 20B are supplied.

The first and second RF amplifiers 20A and 20B amplify each band signal according to the level of the input signal by the AGC circuit (not shown in FIG. 1), and supply it to the diplexer 30. Here, the first and second RF amplifiers 20A and 20B may amplify the band-filtered RF signal according to the control signal output from the AGC circuit to reduce noise and improve the gain of the up-converter. The band-filtered RF signal diplexed by the diplexer 30 is supplied to the first mixer 45. The RF signal supplied to the first mixer 45 is converted into a first intermediate frequency signal by the signal output from the first local oscillator 40 and supplied to the down converter 200. The first intermediate frequency signal supplied to the down converter 200 is supplied to the second mixer 85 after a predetermined band characteristic and amplification through the first intermediate frequency amplifier 60, and the second local oscillator 80. The second intermediate frequency amplifying unit 90 is supplied with the second intermediate frequency converted from the second local frequency. The second intermediate frequency supplied to the second intermediate frequency amplifier 90 is amplified with a predetermined band characteristic and output to the second intermediate frequency signal output terminal OUT.

The operation and effect of the present invention, which operates as described above, is supplied to the control mixer through an RF amplifier whose amplification degree is determined by an AGC circuit that outputs a control signal according to the level of an input signal after band filtering by VHF and UHF bands Minimizing each signal interference improves the up-converter gain and eliminates noise signals.

Claims (2)

An up converter comprising first mixing means for converting the frequency amplified by the first local oscillation means to obtain a first intermediate frequency signal, and a first intermediate frequency for band-amplifying the output of the first mixing means. And second mixing means for frequency-converting the output of the first intermediate frequency stage by means of the second local oscillating means, the second local oscillating means, and obtaining an output of the second mixing means. A down converter comprising at least a second intermediate frequency stage for amplifying, connecting a double tuner input filter to an input terminal of the up converter and simultaneously amplifying the filtered signal, wherein each AGC-capable amplifier and And a diplexer for selecting any one of the signals output from the amplifier and a first mixing means. The up-converter, which consists of a double tuner input filter, an AGC-capable amplifier, a diplexer, and a first mixing means at the input terminal of the converter, is formed with a partition wall and a micro strip line on one side of an independent PCB, and the other side of the PCB is conductive. And fixed in close contact with the insulated chassis, wherein the insulated chassis is formed to be attached to or detached from the wall so as to face the down converter.

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