KR0116899Y1 - A circuit for improving s/n ratio of tuner - Google Patents
A circuit for improving s/n ratio of tuner Download PDFInfo
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- KR0116899Y1 KR0116899Y1 KR2019940015959U KR19940015959U KR0116899Y1 KR 0116899 Y1 KR0116899 Y1 KR 0116899Y1 KR 2019940015959 U KR2019940015959 U KR 2019940015959U KR 19940015959 U KR19940015959 U KR 19940015959U KR 0116899 Y1 KR0116899 Y1 KR 0116899Y1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/80—Camera processing pipelines; Components thereof
- H04N23/81—Camera processing pipelines; Components thereof for suppressing or minimising disturbance in the image signal generation
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- 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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- 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
- H04N5/52—Automatic gain control
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/63—Generation or supply of power specially adapted for television receivers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/294—Indexing scheme relating to amplifiers the amplifier being a low noise amplifier [LNA]
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- Circuits Of Receivers In General (AREA)
- Superheterodyne Receivers (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
튜너의 잡음지수 특성이 전계강도의 강,약에 따라 변화하는 것을 방지하기 위한 튜너의 신호대 잡음비 개선회로는 튜너의 전단에 LNA를 설치하고, 이 LNA는 튜너후단의 IF 복조단에서 발생되는 AGC 전압에 따라 그 증폭도가 변화하게 함으로써, 궁극적으로 튜너의 잡음지수 특성을 안정화시키게 된다.The tuner's signal-to-noise ratio improvement circuit is designed to prevent the tuner's noise figure from changing according to the strength and weakness of the electric field strength. By varying the amplification factor, the noise figure of the tuner is ultimately stabilized.
Description
본 고안은 안테나로 입력된 TV방송신호를 튜닝하여 IF복조단에 제공하기 위한 IF신호를 발생하는 튜너에 관한 것으로, 특히 지역별 전계강도의 강,약에 무관하게 항상 일정한 RF입력신호 레벨을 유지시키도록 함으로써, 튜너의 신호대 잡음비 특성를 향상시키기 위한 튜너의 신호대 잡음비 개선회로에 관한 것이다.The present invention relates to a tuner for generating an IF signal for tuning a TV broadcast signal input to an antenna and providing it to an IF demodulation stage, and in particular, to maintain a constant RF input signal level regardless of the strength or weakness of the electric field strength for each region. The present invention relates to a tuner signal-to-noise ratio improvement circuit for improving the tuner signal-to-noise ratio characteristics.
일반적으로, 안테나로 입력된 TV방송신호(RF신호)는 입력필터 및 동조와 증폭, 그리고 단간동조를 거쳐 믹서에 제공되게 되고, 상기 믹서에서는 발진기의 발진주파수와 RF신호를 믹싱하여 IF신호로 변환된후 증폭 및 IF동조를 거쳐 IF복조단으로 제공되게 된다.In general, a TV broadcast signal (RF signal) input through an antenna is provided to a mixer through an input filter, tuning, amplification, and inter-step tuning. In the mixer, an oscillation frequency of an oscillator is mixed with an RF signal and converted into an IF signal. After the amplification and IF tuning, it is provided to the IF demodulation unit.
이러한 튜너의 종래 회로구성을 제1도에 보이고 있으며, 제1도는 싱글 컨버젼 방식에 따른 UHF/VHF튜너의 예로써, 제1도를 참조하면, 튜너단(100)은 안테나로부터 입력되는 RF신호를 밴드별로 필터링하는 제1,2 입력필터(111,121)와, 상기 각각의 밴드별 입력필터(111,121)를 거친 RF신호를 선택채널에 대해 동조하는 제1,2입력동조기(112,122)와, 상기 입력동조기(112,122)를 거친 선택채널별 RF신호를 IF복조단(200)에서 발생된 AGC전압(VAGC)의 크기에 따라 각각 증폭하는 제1,2 RF증폭기(113,123)와, 상기 RF증폭기(113,123)를 거친 RF신호를 각각 단간동조하여 제1,2믹서(115,125)로 전달하는 제1,2 단간동조기(114,124)와, 상기 단간동조기(114,124)를 거친 RF신호를 각각의 제1,2 발진기(116,126)이 발진주파수로 믹싱하여 IF신호로 변환하는 제1,2 믹서(115,125)와, 상기 믹서(115,125)의 출력을 증폭하고 동조하는 IF 증폭기(117) 및 IF 동조기(118)를 포함한다. 여기에서 제1은 UHF 밴드를, 그리고 제2는 VHF밴드를 지칭한다. 또 그 반대일 수도 있다.A conventional circuit configuration of such a tuner is shown in FIG. 1, and FIG. 1 is an example of a UHF / VHF tuner according to a single conversion method. Referring to FIG. 1, the tuner stage 100 receives an RF signal input from an antenna. First and second input filters 111 and 121 for filtering bands, first and second input tuners 112 and 122 for tuning RF signals passing through the respective band input filters 111 and 121 with respect to a selected channel, and the input tuner. First and second RF amplifiers 113 and 123 for amplifying the RF signals for each selected channel, which have passed through the channels 112 and 122, according to the magnitude of the AGC voltage VAGC generated by the IF demodulation stage 200, and the RF amplifiers 113 and 123, respectively. The first and second stage intermitters 114 and 124 for coarse tuning the rough RF signals to the first and second mixers 115 and 125, and the first and second oscillators 116 and 126 for the RF signals passing through the single stage tuners 114 and 124, respectively. ) Mixes the oscillation frequency into an IF signal and converts the first and second mixers 115 and 125 and the outputs of the mixers 115 and 125. IF amplifier 117 and IF tuner 118 that amplify and tune. Where the first refers to the UHF band and the second refers to the VHF band. And vice versa.
이와 같은 종래의 튜너시스템은 안테나로 입력된 RF신호를 입력필너에서 밴드 프리셀렉트한 수 입력동조기에서 튜닝하여 초단 증폭기이며 AGC되는 RF증폭기로 증폭한 수 선택채널별 단간 동조를 거쳐 믹서에서 IF 신호를 출력하게 되는데, 이때 입력동조기에서의 신호손실 및 RF증폭기에서의 잡음지수가 튜너전체의 잡음지수에 큰 제한을 가하게 된다. 이러한 RF단에서의 잡음지수 특성의 불안정은 주로 약전계 지역에서 나타나게 되는데, 이를 보상하기 위해서는 부우스터가 요구되므로 원가부담을 초래하게 되며, 이와 같은 튜너전단에 부우스터가 장착된 튜너를 강전계 지역에 설치하는 경우에는 상기 부우스터는 강전계에서도 신호증폭을 수행하므로 RF신호의 포화가 일어나 양질의 화면을 얻을 수 없게 되어, 결국, 종래 튜너에서 나타나게 되는 신호대 잡음비의 개선을 위한 튜너전단에의 부우스터 삽입은 강전계 지역을 만족시킬 수 없게 된다는 문제점이 있었다.The conventional tuner system is an ultra-stage amplifier by tuning an RF signal input through an antenna to a band input pre-selected by an input filter and an IF signal from a mixer through inter-stage tuning for several selected channels amplified by an AGC RF amplifier. In this case, the signal loss in the input tuner and the noise figure in the RF amplifier place a large limit on the noise figure of the entire tuner. The instability of the noise figure characteristics in the RF stage is mainly shown in the weak field region, which requires a booster to compensate for this, which incurs a cost burden. A tuner equipped with a booster at the front end of the tuner has a strong field region. If the booster is installed in the booster, the booster performs signal amplification even in a strong electric field, resulting in saturation of the RF signal, thereby making it impossible to obtain a high quality screen. Worcester insertion had a problem that it could not satisfy the strong electric field region.
본 고안은 상기한 문제점을 해결하기 위해서 안출한 것으로, 따라서, 본 고안의 목적은 AGC전압을 이용하여 튜너단의 전단에서 입력 RF신호를 증폭시키도록 함으로서, RF입력신호의 강도에 무관하게 안정된 IF신호를 끌어낼 수 있도록 한 튜너의 신호대 잡음비 개선회로를 제공하는 데 있다.The present invention has been devised to solve the above problems, and therefore, an object of the present invention is to amplify an input RF signal at the front end of a tuner stage by using an AGC voltage, thereby ensuring stable IF regardless of the strength of the RF input signal. It is to provide a signal-to-noise improvement circuit of a tuner to extract the signal.
제1도는 종래의 튜너의 회로구성도.1 is a circuit diagram of a conventional tuner.
제2도는 본 고안에 따른 신호대 잡음비 개선을 위한 튜너의 회로구성도.2 is a circuit diagram of a tuner for improving the signal-to-noise ratio according to the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
100 : 튜너단 130 : LNA(Low Noise Amplifier)100: tuner stage 130: LNA (Low Noise Amplifier)
200 : IF복조단200: IF demodulation group
상기한 본 고안의 목적을 달성하기 위한 기술적인 수단으로써, 본 고안의 회로는 안테나로부터의 RF신호를 필터링하는 제1,2 입력필터, 상기 필터링된 RF신호를 동조시키는 제1,2 입력동조기, 상기 입력동조된 RF신호를 IF 복조단으로부터의 AGC 전압에 따라 증폭하는 제1,2 RF증폭기, 상기 증폭된 RF신호를 단간동조시키는 제1,2단간동조기, 상기 단간동조된 RF신호를 해당 발진주파수와 믹싱하여 IF신호로 변환하는 제1,2 믹서, 상기 IF신호를 증폭 및 동조시키는 IF 증폭기 및 IF 동조기를 포함하는 튜너단과, 상기 튜너단으로부터의 IF신호를 복조하여 베이스밴드신호를 출력함과 동시에 상기 IF신호의 레벨을 검파하여 검파된 레벨에 따른 AGC전압을 제공하는 IF복조단으로 이루어진 수신장치에 있어서, 상기 튜너단의 전단에, 상기 IF복조단으로부터의 AGC전압에 따른 증폭도 RF입력신호를 저잡음 증폭시키는 LNA를 구성하여, 상기 RF입력신호의 레벨에 따라 튜너단의 전단에서 RF입력신호를 증폭시켜 상기 튜너단의 잡음지수 특성을 안정화시키도록 한 것을 특징으로 한다.As a technical means for achieving the above object of the present invention, the circuit of the present invention, the first and second input filter for filtering the RF signal from the antenna, the first and second input tuner for tuning the filtered RF signal, First and second RF amplifiers for amplifying the input-tuned RF signal according to the AGC voltage from an IF demodulation stage, first and second stage inter-tuners for single-time tuning the amplified RF signal, and oscillating the step-tuned RF signal A tuner stage including a first and a second mixer mixing the frequency and converting the IF signal into an IF signal, an IF amplifier and an IF tuner for amplifying and tuning the IF signal, and demodulating the IF signal from the tuner stage to output a baseband signal. And a IF demodulation stage for detecting the level of the IF signal and providing an AGC voltage according to the detected level, wherein the AGC voltage from the IF demodulation stage is placed in front of the tuner stage. According to the present invention, the LNA is configured to low noise amplify the RF input signal, thereby amplifying the RF input signal at the front end of the tuner stage according to the level of the RF input signal to stabilize the noise figure characteristic of the tuner stage. .
이하, 첨부한 도면에 기초하여 본 고안을 설명한다. 제2도는 본 고안에 따른 회로구성도로써, 싱글 컨버젼 방식에 의한 2밴드 튜너를 그 예로 들고 있으며, 여기에서 보인 두 개의 RF신호패스중 하나로 VHF밴드의 RF신호패스이고 다른 하나는 UHF밴드의 RF신호패스이다. 먼저, 안테나로부터 수신된 RF신호는 IF복조단(200)에서 발생되는 AGC전압(VAGC)으로 그 증폭도가 제한되는 LNA(저잡음 증폭기(130)를 통하여 제1,2입력필터)(111,112)로 인가되게 연결하고, 상기 제1입력필터(111)를 거친 제1밴드의 RF신호는 제1입력동조기(112), AGC전압(VAGC)으로 AGC되는 제1 RF증폭 (113), 제1단간동조기(114)를 차례로 통하여 제1발진기(116)의 발진출력이 인가되는 제1믹서(115)로 전달되게 연결하며, 마찬가지로 상기 제2입력필터(121)를 거친 제2밴드의 RF신호는 제2입력동조기(122), AGC전압(VAGC)으로 AGC되는 제2 RF증폭기(123), 제2단간동조기(124)를 차례로 통하여 제2발진기(126)의 발진출력이 인가되는 제2믹서(125)로 전달되게 연결하는데, 상기 제1,2믹서(115,125)에서 출력되는 제1,2 IF신호는 공통의 IF증폭기(117)와 IF동조기(118)를 거쳐 IF복조단(200)으로 전달되게 연결한다.Hereinafter, the present invention will be described based on the accompanying drawings. 2 is a circuit diagram according to the present invention, which is a single-conversion two-band tuner as an example. One of the two RF signal paths shown here is the RF signal path of the VHF band and the other is the RF of the UHF band. Signal path. First, the RF signal received from the antenna is transmitted to the LNA (first and second input filters through the low noise amplifier 130) 111 and 112 whose amplification is limited to the AGC voltage V AGC generated by the IF demodulation stage 200. The RF signal of the first band that is applied and connected through the first input filter 111 is the first input amplifier 112, the first RF amplification 113, AGC by the AGC voltage (V AGC ), between the first stage The oscillation output of the first oscillator 116 is transmitted to the first mixer 115 to which the oscillation output is applied through the tuner 114 in turn. Similarly, the RF signal of the second band passing through the second input filter 121 A second mixer (2) to which the oscillation output of the second oscillator 126 is applied through the second input tuner 122, the second RF amplifier 123 AGC with the AGC voltage V AGC , and the second inter-phase tuner 124. 125, wherein the first and second IF signals output from the first and second mixers 115 and 125 are transferred to the IF demodulation stage 200 through the common IF amplifier 117 and the IF tuner 118. Connect.
이와 같이 구성된 본 고안의 작용 및 효과를 설명하면 다음과 같다. 제2도를 참조하면, TV 방송신호가 안테나를 통하여 LNA(130)에 입력되면 이 신호는 IF복조단(200)에서 발생된 AGC전압(VAGC)의 크기에 따라 결정된 LNA(130)의 증폭도로 증폭되며, 이때 LNA(130)최소 약전계 신호 입력일 경우에는 최대 AGC전압(VAGC)에 의해 이를 최대로 증폭하고 최대강전계 신호 입력일 경우에는 최소 AGC전압(VAGC)에 의해 이를 최소로 증폭하게 되므로, LNA(130)에서 출력되는 RF신호강도는 일정하게 유지된다. 또한, LNA(130)의 고유특성에 따라 입력 RF신호를 저잡음 증폭하게 되므로, 잡음지수에 결정적으로 영향하게 되는 초단증폭기에서의 저잡음 증폭에 의해 궁극적으로 신호대 잡음비가 개선될 수 있는 계기를 제공하게 되는 것이다.Referring to the operation and effects of the present invention configured as described above are as follows. Referring to FIG. 2, when a TV broadcast signal is input to the LNA 130 through an antenna, the signal is amplified by the LNA 130 determined according to the magnitude of the AGC voltage V AGC generated by the IF demodulation stage 200. In this case, the LNA 130 amplifies the maximum by the maximum AGC voltage (V AGC ) in the case of the minimum weak field signal input and minimizes it by the minimum AGC voltage (V AGC ) in the case of the maximum strong field signal input. Therefore, the RF signal strength output from the LNA 130 is kept constant. In addition, the low noise amplification of the input RF signal according to the inherent characteristics of the LNA 130, thereby providing an instrument that can ultimately improve the signal-to-noise ratio by low noise amplification in the ultra-short amplifier that is critically affected by the noise figure will be.
이와 같이, LNA(130)에서 양호한 잡음지수특성으로 증폭된 RF신호는 튜너(100)의 제1,2입력필터(11,121)를 거쳐 밴드선택이 이루어지게 되고, 각각의 제1,2 입력필터를 거친 제1,2 RF밴드신호는 각각 제1,2 입력동조기(11,2122)에서 입력동조된후 제1,2 RF증폭기(113,123)에서 증폭된다. 이때 제1,2 RF증폭기(113,123)는 IF복조단(200)의 AGC전압(VAGC)에 의해 자동이득 조정되어 각각의 제1,2 RF신호를 증폭하게 된다.As described above, the RF signal amplified by the LNA 130 with good noise figure characteristics is subjected to band selection through the first and second input filters 11 and 121 of the tuner 100, respectively. The rough first and second RF band signals are input-tuned by the first and second input tuners 11 and 2122, respectively, and then amplified by the first and second RF amplifiers 113 and 123, respectively. At this time, the first and second RF amplifiers 113 and 123 are automatically adjusted by the AGC voltage V AGC of the IF demodulation stage 200 to amplify the respective first and second RF signals.
이후, 제1,2 RF증폭기의 출력은 제1,2 단간동조기(114,124)를 거치면서 채널선택된 다음, 각각의 제1,2 믹서(115,125)에서 각각의 제1,2 발진기(116,126)의 발진기 출력으로 믹싱되어 제1,2 IF신호가 발생된다. 이러한 제1,2 IF신호는 공통 IF증폭기(117) 및 IF동조기(118)를 거쳐 IF복조단(200)에 입력됨으로서, 상기 IF복조단(200)에서는 베이스 밴드 신호를 추출할 수 있게 되는 것이다.Thereafter, the outputs of the first and second RF amplifiers are channel-selected while passing through the first and second stage interlockers 114 and 124, and then the oscillators of the respective first and second oscillators 116 and 126 in the first and second mixers 115 and 125 respectively. The output is mixed with the first and second IF signals. The first and second IF signals are input to the IF demodulation stage 200 through the common IF amplifier 117 and the IF tuner 118, so that the baseband signal can be extracted from the IF demodulation stage 200. .
이상에서 설명한 바와 같은 본 고안은 기존의 튜너전단에 잡음지수 개선을 위한 LNA를 설치하고 이 LNA는 AGC전압에 의해 그 증폭도가 변화되게 함으로써 RF입력신호(안테나 신호)의 강, 약에 따른 신호포와 또는 잡음지수특성의 현저한 저하 현상을 방지할 수 있게 되므로, 튜너의 전체적인 잡음지수특성을 향상시킬 수 있게 된다.As described above, the present invention installs an LNA for improving the noise figure in the existing tuner front end and changes the amplification of the LNA by the AGC voltage so that the signal format according to the strength and weakness of the RF input signal (antenna signal) and Alternatively, since the significant degradation of the noise figure can be prevented, the overall noise figure of the tuner can be improved.
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KR2019940015959U KR0116899Y1 (en) | 1994-06-30 | 1994-06-30 | A circuit for improving s/n ratio of tuner |
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KR2019940015959U KR0116899Y1 (en) | 1994-06-30 | 1994-06-30 | A circuit for improving s/n ratio of tuner |
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