KR20100022806A - Input filter circuit of tuner - Google Patents

Input filter circuit of tuner Download PDF

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Publication number
KR20100022806A
KR20100022806A KR1020080081491A KR20080081491A KR20100022806A KR 20100022806 A KR20100022806 A KR 20100022806A KR 1020080081491 A KR1020080081491 A KR 1020080081491A KR 20080081491 A KR20080081491 A KR 20080081491A KR 20100022806 A KR20100022806 A KR 20100022806A
Authority
KR
South Korea
Prior art keywords
input filter
band
frequency signal
high frequency
filter circuit
Prior art date
Application number
KR1020080081491A
Other languages
Korean (ko)
Inventor
김영근
Original Assignee
엘지이노텍 주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 엘지이노텍 주식회사 filed Critical 엘지이노텍 주식회사
Priority to KR1020080081491A priority Critical patent/KR20100022806A/en
Publication of KR20100022806A publication Critical patent/KR20100022806A/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/16—Tuning without displacement of reactive element, e.g. by varying permeability
    • H03J3/18—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance
    • H03J3/185—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance with varactors, i.e. voltage variable reactive diodes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/24—Continuous tuning of more than one resonant circuit simultaneously, the circuits being tuned to substantially the same frequency, e.g. for single-knob tuning
    • H03J3/26—Continuous tuning of more than one resonant circuit simultaneously, the circuits being tuned to substantially the same frequency, e.g. for single-knob tuning the circuits being coupled so as to form a bandpass filter
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
    • H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
    • H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
    • H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/50—Tuning indicators; Automatic tuning control

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Filters And Equalizers (AREA)

Abstract

The present invention relates to an input filter circuit of a tuner.

The present invention includes a switching unit for blocking or attenuating a low frequency signal and a band below or below a tuned band in an input filter circuit that blocks a low frequency signal from a high frequency signal received by an antenna. By blocking and attenuating a band below the band, the attenuation does not occur in the high frequency signal of the selected band, so that interference can be improved in the selected band.

Description

Input filter circuit of tuner {INPUT FILTER CIRCUIT OF TUNER}

1 is an input filter circuit diagram of a conventional tuner.

2 is a waveform diagram of an input filter circuit of FIG.

3 is an input filter circuit diagram of a tuner according to an embodiment of the present invention.

4 is an operation circuit diagram of selecting a VHF-L band of the input filter circuit of FIG.

5 is a waveform diagram of an input filter circuit of FIG. 4.

FIG. 6 is a circuit diagram illustrating the operation of selecting the VHF-H band of the input filter circuit of FIG.

7 is a VHF-H band waveform diagram of the input filter circuit of FIG.

FIG. 8 is a circuit diagram illustrating operation of UHF band selection of the input filter circuit of FIG.

9 is a UHF band waveform diagram of the input filter circuit of FIG.

* Description of the symbols for the main parts of the drawings *

31; Input filter 32; Low noise amplifier

33; A switching unit 34; Stabilization

The present invention relates to an input filter circuit of a tuner.

In general, a tuner is a device that selects and receives a desired broadcasting channel from a high frequency signal received from an antenna. The tuner includes a VIEF band having a reception band ranging from tens of MHz to hundreds of MHz, and hundreds of MHz. The UHF band (hereinafter referred to as UHF) band up to several tens of GHz is selected and received, and the VHF band is divided into VHF-L and VHF-H bands for reception.

As shown in FIG. 1, a tuner that receives and distinguishes as described above has a low noise while a high frequency signal (50 to 950 MHz) input through the antenna ANT is removed through the input filter 11 to remove a high frequency signal of 50 MHz or less. All are input to the amplifier (LNA) 12 and output.

At this time, the output high frequency signal is confused in the VHF-H band and UHF band by the composite secondary order (CSO) that causes two signals to be combined to interfere with one signal due to the characteristics of the active circuitry of the low noise amplifier 12. This happens badly.

For example, as shown in FIG. 2, when the UHF high frequency signal 471.25 MHZ is tuned, the high frequency signal received from the antenna ANT passes through the low noise amplifier 12 in the process of passing through the VHF-L high frequency signal f1. ) And the VHF-H high frequency signal f2 are combined (f1 + f2) so that the tuned high frequency signal is in the range of 471.25 to 475.45 MHZ, and the sum of the high frequency signals f1 + f2 crosstalks to the tuned 471.25MHZ. There is a problem that a bit (interference) occurs on the screen.

The present invention improves the signal interference of the tuner.

An embodiment of the present invention provides an input filter for blocking a low high frequency signal input to an antenna and passing only a high high frequency signal; A low noise amplifier for amplifying and outputting a high frequency signal passing through the input filter; A switching unit which attenuates a frequency band or less selected by the input filter; And a stabilization unit for stabilizing the operation of the switching unit.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

3 is an input filter circuit diagram of a tuner according to an embodiment of the present invention, FIG. 4 is an operation circuit diagram of selecting a VHF-L band of the input filter circuit of FIG. 3, and FIG. 5 is a waveform diagram of the input filter circuit of FIG. 4. to be.

6 is an operation circuit diagram of selecting the VHF-H band of the input filter circuit of FIG. 3, FIG. 7 is a waveform diagram of the VHF-H band of the input filter circuit of FIG. 6, and FIG. 8 is a UHF band of the input filter circuit of FIG. Fig. 9 is an operation circuit diagram when selected, and Fig. 9 is a UHF band waveform diagram of the input filter circuit of Fig. 8.

One embodiment of the present invention includes an input filter 31, a low noise amplifier 32, a switching unit 33, and a stabilizer (34).

The input filter 31 attenuates a signal of 50 MHz or less from a high frequency signal (40 to 950 MHz) received from the antenna ANT, and connects the first condenser C311 and the first coil to be connected in parallel so as to pass only a higher frequency range. LT311); And a second coil LT312 and a second capacitor C312 connected in series through the coupling capacitor CC.

The low noise amplifier 32 amplifies and outputs all frequencies of 50 MHz or more passed by the input filter 31.

The switching unit 33 is connected to the input filter 31 to attenuate the selected high frequency signal band or less when selecting a high frequency signal.

The switching unit 33 selects the VHF-L and UHF bands to the input filter 31.

The selection signal of the VHF-L band includes a third capacitor (C331), a first resistor (R331), and a first diode connected in parallel with the coupling capacitor (CC) of the input filter (31) to the first capacitor (C311). A connection may be made through D1, the first coil LT311, and the third coil LT331.

The selection signal of the UHF band is connected between the first coil LT311 and the third coil LT331 through a second resistor R332, a fourth capacitor C332, and a second diode D2.

The stabilization unit 34 is connected to the cathode terminal of the first diode (D1) of the switching unit 33 through the coupling capacitor (CC) of the input filter 31, the stabilization unit 34 is It is connected to voltage divider R341 and R342.

According to an exemplary embodiment of the present invention, when the high frequency signal is tuned in the VHF-L band, the VHF-L band selection signal is provided through the first resistor R331 at the anode terminal of the first diode D1 of the switching unit 33. Is input to conduct the first diode D1, so that the circuit is configured as shown in FIG.

Therefore, the high frequency signal received through the antenna ANT is connected to the first condenser C311 of the input filter 31 and the third condenser C331 of the switching unit 33 connected in parallel with the first condenser C311. As shown in FIG. 5, the second coil LT312 and the second capacitor C312 are attenuated by a high frequency signal of 50 MHz or less based on 55.25 MHz through the first coil LT311 and the coupling capacitor CC. Since the attenuation does not occur above 50MHz.

When no signal is input to the switching unit 33 when the high frequency signal is tuned in the VHF-H band, the switching unit 33 does not operate and is configured as a circuit as shown in FIG. 6. do.

Therefore, the high frequency signal received through the antenna ANT is connected to the first condenser C311 and the first condenser C311 of the input filter 31 in parallel with the third coil LT331 and the first coil LT311. And the high frequency signal of the VHF-L band based on 140 MHz as shown in FIG. 7 by the second coil LT312 and the second capacitor C312 through the coupling capacitor CC. The -H band is not affected by the selected VHF-L band.

On the other hand, when the high frequency signal is selected in the UHF band, the UHF band selection signal is input to the enowood terminal of the second diode D2 of the switching unit 33 through the second resistor R332 and thus the second diode D2. Since it is to be conducted, the circuit shown in Fig. 8 is constituted.

Therefore, the high frequency signal received through the antenna ANT is transmitted to the first capacitor C311 of the input filter 31 and the third capacitor C331 of the switching unit 33, the third coil LT331, and the switching unit 33. VHF-L and VHF- based on 400 MHz by the second coil LT312 and the second capacitor C312 through the fourth capacitor C332 and the coupling capacitor CC of FIG. Since the high frequency signal of the H band is attenuated, the UHF band is not affected by the VHF-L and VHF-H bands.

As described above, the present invention includes a switching unit for blocking or attenuating a band below a band to be tuned to an input filter circuit of a tuner, so that signal attenuation does not occur due to a band below the band to be tuned when the band is tuned. It is possible to improve the interference in the station band.

Claims (6)

An input filter for blocking a low high frequency signal input to an antenna and passing only a high high frequency signal; A low noise amplifier for amplifying and outputting a high frequency signal passing through the input filter; A switching unit which attenuates a frequency band or less selected by the input filter; And An input filter circuit of a tuner comprising a stabilization unit for stabilizing the operation of the switching unit. The method of claim 1, And the switching unit selects VHF-L and UHF bands to the input filter. The method of claim 2, And the selection signal of the VHF-L band is connected to a coupling capacitor of the input filter through a third capacitor connected in parallel to the first capacitor and a first resistor, a first diode, and a third coil. The method of claim 2, And the selection signal of the UHF band is connected between the first coil and the third coil through a second resistor, a fourth capacitor, and a second diode. The method of claim 1, An input filter circuit of a tuner, wherein the stabilization part is connected to the cathode terminal of the first diode of the switching part. The method of claim 1, An input filter circuit of a tuner, wherein the stabilization unit is a voltage divider resistor.
KR1020080081491A 2008-08-20 2008-08-20 Input filter circuit of tuner KR20100022806A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020080081491A KR20100022806A (en) 2008-08-20 2008-08-20 Input filter circuit of tuner

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020080081491A KR20100022806A (en) 2008-08-20 2008-08-20 Input filter circuit of tuner

Publications (1)

Publication Number Publication Date
KR20100022806A true KR20100022806A (en) 2010-03-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020080081491A KR20100022806A (en) 2008-08-20 2008-08-20 Input filter circuit of tuner

Country Status (1)

Country Link
KR (1) KR20100022806A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160104969A (en) * 2015-02-27 2016-09-06 엘지이노텍 주식회사 Tuner circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160104969A (en) * 2015-02-27 2016-09-06 엘지이노텍 주식회사 Tuner circuit

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