KR890007292Y1 - Amplification extent variable circuit of pre-amp - Google Patents
Amplification extent variable circuit of pre-amp Download PDFInfo
- Publication number
- KR890007292Y1 KR890007292Y1 KR2019860011847U KR860011847U KR890007292Y1 KR 890007292 Y1 KR890007292 Y1 KR 890007292Y1 KR 2019860011847 U KR2019860011847 U KR 2019860011847U KR 860011847 U KR860011847 U KR 860011847U KR 890007292 Y1 KR890007292 Y1 KR 890007292Y1
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- KR
- South Korea
- Prior art keywords
- intermediate frequency
- coil
- amplifier stage
- transistor
- frequency amplifier
- Prior art date
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
- H03G3/3068—Circuits generating control signals for both R.F. and I.F. stages
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G1/00—Details of arrangements for controlling amplification
- H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
- H03G1/0035—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using continuously variable impedance elements
- H03G1/0082—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using continuously variable impedance elements using bipolar transistor-type devices
Abstract
내용 없음.No content.
Description
제1도는 종래의 회로도.1 is a conventional circuit diagram.
제2도는 본 고안에 따른 회로도.2 is a circuit diagram according to the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
R5: 저항 L2: 코일R 5 : Resistance L 2 : Coil
TR2: 트랜지스터 OP1: 비교기TR 2 : Transistor OP 1 : Comparator
본 고안은 신호대 잡음비를 향상시키기 위하여 미소한 입력신호를 주증폭회로에 넣기전에 미리 증폭하는 프리앰프의 증폭도 가변회로에 관한 것으로, 특히 안테나에 유기되는 전계의 세기가 약한 경우에 프리앰프의 증폭도를 높게하여 충분히 원하는 신호성분이 중간주파단에 인가되게한 프리앰프의 증폭도 가변회로에 관한 것이다.The present invention relates to a variable amplification circuit of a preamplifier that amplifies a small input signal before input into the main amplifier circuit to improve the signal-to-noise ratio. The amplification of the preamplifier is also related to a variable circuit in which a desired signal component is sufficiently applied to the intermediate frequency stage by increasing.
종래에는 제1도에 도시한 바와같이 안테나(1)와 튜너(2)와, 저항(R1-R4), 콘덴서(C1-C3), 코일(L1) 및 트랜지스터(TR1)로 구성된 프리앰프(3)와 중간주파증폭단(4)으로 구성된 것으로, 안테나(1)에 유기된 신호는 튜너(2)에서 RF증폭되고 다시 프리앰프(3)에서 증폭되어 중간 주파증폭단(4)에 입력되는바, 이때 코일(L1)과 저항(R4)은 톱니파필터의 위상과 증폭도를 결정해 주게되며, 중간 주파증폭단(4)에서는 도래전파에 의한 전류와 수신기내에 마련된 국부발진기로부터의 전류를 합성하여 얻은 중간주파수의 전압을 증폭하여 자동이득 조절전압을 튜너(2)에 귀환시킴과 아울러 중간주파증폭단(4)의 증폭신호를 출력하게 된다.Conventionally, as shown in FIG. 1, the antenna 1, the tuner 2, the resistors R 1- R 4 , the capacitors C 1- C 3 , the coil L 1 , and the transistor TR 1 . It consists of a preamplifier (3) and the intermediate frequency amplifier stage (4) consisting of, the signal induced in the antenna (1) is RF-amplified by the tuner (2) and amplified by the preamplifier (3), the intermediate frequency amplifier stage (4) In this case, the coil L 1 and the resistor R 4 determine the phase and amplification degree of the sawtooth filter, and in the intermediate frequency amplifier stage 4, the current from the incoming wave and the local oscillator provided in the receiver By amplifying the voltage of the intermediate frequency obtained by synthesizing the current, the automatic gain control voltage is returned to the tuner 2 and the amplified signal of the intermediate frequency amplifier stage 4 is output.
그러나, 이와같은 종래회로에 있어서는 안테나에 유기된 전계의 세기가 약하게 되면 RF자동이득조절과 중간주파 자동이득조정의 한계에 의해 좋은 영상을 얻기가 어려웠고 특히 RF 자동이득조정에서 최대증폭을 하여도 원하는 신호성분이 톱니파 필터를 지나고 나면 그의 이득이 너무 저하되어 신호대 잡음비가 나빠 화면상에 잡음이 발생하는 등의 단점이 있었다.However, in such a conventional circuit, when the strength of the electric field induced by the antenna becomes weak, it is difficult to obtain a good image due to the limitations of the RF automatic gain adjustment and the intermediate frequency automatic gain adjustment. After the signal component has passed through the sawtooth filter, its gain is so low that the signal-to-noise ratio is bad, resulting in noise on the screen.
본 고안은 이와같은 종래의 단점을 감안하여, 프리앰프의 증폭도를 입력신호에 따라 가변시켜 톱니파 필터에서 이득이 감쇠되어도 충분히 큰 원래의 신호성분을 유지할 수 있도록 안출한 것으로 첨부한 도면에 의해 이를 상세히 설명하면 다음과 같다. 첨부한 제2도는 본 고안에 따른 회로도로써 이에 도시한 바와같이, 안테나(1), 튜너(2), 프리앰프(3) 및 중간주파증폭단(4)으로 된 것에 있어서, 상기 중간주파 증폭단(4)의 RF 자동이득조절출력단자(RA)는 반전입력단자(-)에 기준전압단자(Vref)가 접속된 비교기(OP1)의 비반전입단자(+)에 접속하여 그 비교기(OP1)의 출력측은 트랜지스터(TR2)의 베이스에 접속하고, 그의 에미터는 코일(L1)(L2) 및 저항(R4)(R5)의 공통접속점에 접속하며, 그의 콜렉터는 상기 코일(L2), 저항(R5) 및 트랜지스터(TR1)의 콜렉터에 공통접속점에 접속한 것이다.In view of the above-mentioned drawbacks, the present invention is designed to maintain the original signal component sufficiently large even if the gain in the sawtooth filter is attenuated by varying the amplification degree of the preamplifier according to the input signal. The explanation is as follows. 2 is a circuit diagram according to the present invention, and as shown therein, the intermediate frequency amplifier stage 4 includes an antenna 1, a tuner 2, a preamplifier 3, and an intermediate frequency amplifier stage 4. ) RF automatic gain control output terminal (RA) of the inverting input terminal (- connected to the non-inverting ipdanja (+) of the comparator (OP 1), the reference voltage terminal (Vref) connected to a) of the comparator (OP 1) The output side is connected to the base of the transistor TR 2 , its emitter is connected to the common connection point of the coil L 1 (L 2 ) and the resistor R 4 (R 5 ), and its collector is the coil L 2. ), The resistor R 5 and the collector of the transistor TR 1 are connected to a common connection point.
이와같이 구성한 본 고안의 작용 및 효과를 상세히 설명하면 다음과 같다.Referring to the operation and effects of the present invention configured in this way as follows.
안테나(1)에 유기된 신호는 튜너(2)에서, 중간주파증폭단(4)으로부터 인가되는 RF 자동이득조절신호에 의해 증폭되어 콘덴서(C1)를 통해 트랜지스터(TR1)의 베이스에 입력되고, 이 입력신호는 트랜지스터(TR1)의 콜렉터로부터 증폭출력되어 콘덴서(C3)를 통해 중간주파증폭단(4)에 입력된다.The signal induced in the antenna 1 is amplified by the RF auto gain control signal applied from the intermediate frequency amplifier stage 4 at the tuner 2 and input to the base of the transistor TR 1 through the capacitor C 1 . The input signal is amplified and output from the collector of the transistor TR 1 and input to the intermediate frequency amplifier stage 4 through the capacitor C 3 .
이때, 코일(L1) 및 저항(R4)은 톱니파 필터의 위상과 증폭도를 결정하게 되고 코일(L2)및 저항(R5)은 이득을 가변하는 역할을 하게 된다.At this time, the coil L 1 and the resistor R 4 determine the phase and the amplification degree of the sawtooth filter, and the coil L 2 and the resistor R 5 serve to vary the gain.
이와같이하여 중간주파증폭단(4)에서 상기 튜너(2)로 귀환되는 지연 자동이득조정신호는 비교기(OP1)의 비반전입력단자(+)에 인가되어 그의 반전입력단자(-)에 인가된 기준 전압(Vref)과 비교되게 된다. 이때 중간주파증폭단(4)으로부터 출력된 RF 자동이득조절전압이 기준전압(Vref)보다 크게되면 비교기(OP1)으로부터 고전위가 출력되어 트랜지스터(TR2)베이스에 인가되므로 그가 오프되어 상호병렬접속된 코일(L1) 및 저항(R4), 상호병렬접속된 코일(L2) 및 저항(R5)이 직렬접속되게되며, 중간주파증폭단(4)으로부터 출력된 RF자동이득조절전압이 비교기(OP1)의 기준전압(Vref)보다 작으며 비교기(OP1)로부터 저전위가 출력되어 트랜지스터(TR2)의 베이스에 인가되므로 그가 온되어 트랜지스터(TR1)의 콜렉터의 부하는 상호병렬접속된 코일(L1) 및 저항(R4)으로 이루어지게 된다.In this way, the delay automatic gain adjustment signal fed back from the intermediate frequency amplifier stage 4 to the tuner 2 is applied to the non-inverting input terminal (+) of the comparator OP 1 and applied to its inverting input terminal (-). It is compared with the voltage Vref. At this time, if the RF automatic gain control voltage output from the intermediate frequency amplifier stage 4 is greater than the reference voltage Vref, a high potential is output from the comparator OP 1 and applied to the transistor TR 2 base, so that it is turned off and connected in parallel. The coil L 1 and the resistor R 4 , the parallel coil L 2 and the resistor R 5 are connected in series, and the RF automatic gain control voltage output from the intermediate frequency amplifier stage 4 is a comparator. (OP 1) is smaller than the reference voltage (Vref) of the comparator since the low potential is output from the (OP 1) is applied to the base of the transistor (TR 2) is he on-load of the collector of the transistor (TR 1) are mutually connected in parallel Coil L 1 and resistor R 4 .
이와같이하여 중간주파증폭단(4)으로부터의 RF 자동이득조절이 전압에 따라 부족한 이득을 보상해줌으로써 톱니파필터에서 감소되어도 선택된 신호를 중간주파증폭단(4)에 전송하여 프리앰프의 이득을 가변하게 된다.In this way, the automatic adjustment of the RF gain from the intermediate frequency amplifier stage 4 compensates for the insufficient gain according to the voltage, so that the selected signal is transmitted to the intermediate frequency amplifier stage 4 even if the sawtooth filter is reduced, thereby varying the gain of the preamplifier.
이상에서 설명한 바와같이 본 고안은 프리앰프의 증폭도를 입력신호에 따라 가변시켜 줌으로써 원래의 신호성분을 중간부파증폭단에 충분히 전송하여 좋은 영상의 화면을 얻을수 있는 효과가 있게 된다.As described above, the present invention varies the amplification degree of the preamplifier according to the input signal, thereby effectively transmitting the original signal component to the intermediate spectral amplifier stage, thereby obtaining a good image screen.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR2019860011847U KR890007292Y1 (en) | 1986-08-06 | 1986-08-06 | Amplification extent variable circuit of pre-amp |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR2019860011847U KR890007292Y1 (en) | 1986-08-06 | 1986-08-06 | Amplification extent variable circuit of pre-amp |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| KR880005376U KR880005376U (en) | 1988-05-12 |
| KR890007292Y1 true KR890007292Y1 (en) | 1989-10-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR2019860011847U KR890007292Y1 (en) | 1986-08-06 | 1986-08-06 | Amplification extent variable circuit of pre-amp |
Country Status (1)
| Country | Link |
|---|---|
| KR (1) | KR890007292Y1 (en) |
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1986
- 1986-08-06 KR KR2019860011847U patent/KR890007292Y1/en not_active IP Right Cessation
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| Publication number | Publication date |
|---|---|
| KR880005376U (en) | 1988-05-12 |
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