KR19990003009A - RF input gain controller with 2 inputs - Google Patents

Abstract

The present invention is known Al. F. (RF) When the automatic gain controller has two input types, the pin diode for switching the two input types is known. It is a two-input automatic gain controller of two-input type that widens the reduction range of the automatic gain controller by using for automatic gain control, and is used to amplify and apply the tuner's RF signal. A first input terminal and a second input terminal, a third input terminal to which the automatic gain control voltage V _AGC outputted from the automatic gain control detector is applied, an output terminal to which the output signal is applied to the second R. amp amplifier of the tuner, and a relay A first pin diode for switching between the point, the first input terminal and the relay point, a second pin diode for switching between the second input terminal and the relay point, and an automatic gain control connected between the output terminal and the relay point. a pin diode, a transistor and a resistor configuration, and an automatic gain control buffer, a base end teodan emitter and collector stage to be applied to the output buffers to the automatic gain control voltage (V _AGC) input through the third input terminal to the Compared with a transistor, a first resistor connected between the base end and the third input end, a second resistor connected between the collector end and the relay point, a third resistor connected between the emitter and ground, and between the relay point and ground. It characterized in that it comprises a fourth resistor connected to.

Description

RF input automatic gain controller

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to RF gain controller (AGC) automatic gain controller (AGC). In particular, when the RF gain controller has a two-input form, the pin diode for switching the two-input form is known. The present invention relates to a two-input automatic gain controller of a two-input type which is used as a pin diode for automatic gain control to widen the reduction range of an automatic gain controller.

In general, the automatic gain controller automatically controls the gain of the receiver according to the strength of the received radio wave to always obtain a constant image detection output and serves to reduce the change in contrast. 1 is a block diagram showing the configuration of a general automatic gain control device. As shown here, the automatic gain control device detects a filter 11 for removing noise of an amplified video signal and a video signal from which the noise is removed. Automatic gain control detector 12, an IF gain controller 13 for controlling the gain of the intermediate frequency amplifying circuit in accordance with the detected video signal, and an R.F of the detected video signal and tuner. And an automatic gain controller (14) for controlling the gain of the tuner's high frequency amplification circuit in accordance with the (RF) signal. The automatic gain controller configured as described above controls the gain of the tuner and the image intermediate frequency amplification circuit according to the strength of the input signal using the detected image signal.

Fig. 2 is a circuit diagram showing a circuit of an R.F.auto gain controller of the conventional two-input type. As shown here, the circuit of the R.F.automatic gain controller of the conventional two-input type is the tuner of the tuner. A first input terminal 21 and a second input terminal 22 to which the signal is amplified and applied; a third input terminal 23 to which an automatic gain control voltage V _AGC output from the automatic gain control detector is applied; An output stage 24 for applying the output signal of the automatic gain controller to the tuner amplifier, the first relay point 25 and the second relay point 26, the first input terminal 21 and the first signal; Switching first pin diodes D1 and D2 connected between the first relay point 25, and switching second pin diodes D3 connected between the second input terminal 22 and the first relay point 25. D4), pin gains D5 and D6 for automatic gain control connected between the output terminal 24 and the second relay point 25, a transistor and a resistor, and the third input terminal 23 and the output terminal 24. An automatic gain control buffer 27 connected between the first capacitor C1 and the output terminal 23 for blocking the DC current connected between the first relay point 25 and the second relay point 26. And a second capacitor (C2) for blocking DC current for applying the output signal of the F. automatic gain controller to the input of the second R. amp amplifier of the tuner for blocking the DC current. The input stage and R.F. automatic gain controller are separated by pin diode, so there is no relationship between the switching pin diodes (D1, D2, D3, D4) of the input stage and the pin gain for automatic gain control of R.F.gain controller. none. When the control voltage (for example, V1 = 5V, V2 = 0V or V1 = 0V, V2 = 5V) is applied to the switching voltage V1 or V2 according to the input terminal to be selected, the output signal of the tuner's first R. amp amplifier. Is inputted through the first input terminal or the second input terminal by the first pin diodes D1 and D2 or the second pin diodes D3 and D4 for switching. Figure 3 (a) is buffered in the automatic gain control voltage as a graph showing the (V _AGC), an automatic gain control voltage outputted from the automatic gain control detector (V _AGC) is an automatic gain control buffer 27 for the input field Is applied to the output terminal 24, and a potential is supplied to the pin gains D5 and D6 for the automatic gain control in which the positive terminal is connected to the output terminal 24 to the signal input through the input terminals 21 and 22. Accordingly, the resistance values of the pin gains D5 and D6 for the automatic gain control are adjusted to output a control signal for attenuating the R. F. signal to the second R. F. amplifier through the output terminal 24. Generally, a pin ion is a diode having a junction of regions showing intrinsic properties between a P-type semiconductor and an N-type semiconductor, and is a diode for switching or attenuating microwaves using a change in conductivity. FIG. 3B is a graph showing the resistance between the pin diodes with respect to the voltage between the silver pin diodes or the current flowing through the pin diodes.

In the conventional circuit, the RF stage is composed of two amplifiers and two pin diodes, and the two diodes can only realize attenuation of about 23 dB at high frequencies, so the signal input to the mixer during a strong electric field Is too large to cause saturation or worse bit characteristics.

The present invention is to solve such a conventional problem, the object of the present invention is to use the pin diode for switching the two-input form as a pin diode for RF gain control RF gain automatic gain The present invention provides a two-input automatic gain controller that expands the reduction range of the controller.

1 is a block diagram showing the configuration of a general automatic gain control device.

Fig. 2 is a circuit diagram showing a circuit of an R. automatic gain controller of the conventional two-input form.

FIG. 3A is a graph illustrating the relationship between the automatic gain control voltage V _AGC and the input electric field, and FIG. 3B is a voltage between both ends of the pin diode or both ends of the pin diode. This graph shows the relationship between the current flowing through and the resistance between the pin diodes.

4 is a circuit diagram showing a circuit diagram of an R.F. automatic gain controller of the two-input form according to the embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

41: first input terminal, 42: second input terminal, 43: third input terminal, 44: output terminal, 45: first relay point, 46: second relay point, 47: automatic gain control buffer, Q1: transistor, R1, R2 , R3, R4,: Resistor, C1, C2: DC current blocking capacitor, V1, V2: Switching voltage

The present invention for achieving the above object,

A first input terminal and a second input terminal to which the RF signal of the tuner is amplified and applied, a third input terminal to which an automatic gain control voltage V _AGC output from the automatic gain control detector is applied, and an output signal An output terminal applied to a second RF amplifier of the tuner, a relay point, a switching first pin diode connected between the first input terminal and the relay point, and a second input terminal connected to the relay point It consists of a switching second pin diode, an automatic gain control pin diode connected between the output terminal and the relay point, a transistor and a resistor, and buffers the automatic gain control voltage (V _AGC ) input through the third input terminal to the output terminal. In a two-input RF gain controller with an automatic gain control buffer,

A transistor having a base end, an emitter end, and a collector end, a first resistor connected between the base end and a third input end, a second resistor connected between the collector end and the relay point, and a third connected between the emitter and ground And a fourth resistor connected between the relay point and the ground.

Hereinafter, the configuration and operation of the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a circuit diagram showing a circuit of an A.F. automatic gain controller in a two-input form according to an embodiment of the present invention. As shown here, an A.F. automatic gain controller according to an embodiment of the present invention is shown in FIG. And a first input terminal 41 and a second input terminal 42 to which an RF signal of the tuner is amplified and applied, and a third input terminal to which an automatic gain control voltage V _AGC output from the automatic gain control detector is applied. 43), an output terminal 44 for applying the output signal to the second R. amp amplifier of the tuner, a first relay point 45 and a second relay point 46, and two pin diodes are connected in series. Switching first pin diodes (D1, D2) for switching the cathode is connected to the first relay point 45, and two pin diodes are connected in series, the switching agent is connected to the cathode in the first relay point 45 2 pin diodes (D3, D4) and two pin diodes are connected in series and the pin for automatic gain control that the cathode is connected to the second relay point 46 An automatic gain control buffer 47 composed of diodes D5 and D6, a transistor and a resistor, and buffering the automatic gain control voltage V _AGC input through the third input terminal 43 and applying it to the output terminal 44; A transistor (Q1) having a base end, an emitter end, and a collector end, a first resistor (R1) connected between the base end and the third input end (43), and connected between the collector end and the first relay point (45). The second resistor R2, the third resistor R3 connected between the emitter and the ground, the fourth resistor R4 connected between the first relay point 45 and the ground, and the first relay point ( A first capacitor C1 connected between the second relay point 46 and the second relay point 46 to block the DC current; and a second tuner connected to the output terminal 44 to block the DC current among the output signals of the output terminal 44. And a second capacitor C2 applied to the RF amplifier.

The RF input automatic gain controller of the two-input form according to the present invention shown in FIG. 4 is provided with the transistor Q1 and the resistor (a) in the conventional two-type automatic gain controller of the conventional two input form shown in FIG. R1, R2 and R3 are added to relay the automatic gain control voltage V _AGC to the switching first pin diodes D1 and D2 or the switching first pin diodes D3 and D4, thereby switching the pin diodes D1. , D2, D3, D4) can be used for automatic gain control. As shown in FIG. 3A, when the automatic gain control voltage V _AGC rises to a high voltage during the weak electric field, the potential of the base terminal of the transistor Q1 is also increased and a lot of current flows. Eventually, when a control voltage (for example, 5 V) is applied to the switching voltage V1 or V2 according to the input terminal to be selected, the switching first pin diodes D1 and D2 or the switching first pin diode D3, Since a large amount of current flows in D4), the resistances of the first pin diodes D1 and D2 for switching or the first pin diodes D3 and D4 for switching are reduced as shown in FIG. Therefore, attenuation becomes small. On the contrary, when the automatic gain control voltage V _AGC becomes a low voltage during the strong electric field, the potential of the base terminal of the transistor Q1 is lowered and the current flows less. When a control voltage (for example, 5 V) is applied to the first pin diodes D1 and D2 for switching or the first pin diodes D3 and D4 for switching, according to the selected input terminal, a small current flows. As shown in FIG. 5, the resistance of both ends of the switching first pin diodes D1 and D2 or the switching first pin diodes D3 and D4 is increased, thereby increasing the loss. Therefore, the attenuation of the switching pin diode at the input stage can be adjusted using the automatic gain control voltage V _AGC according to the electric field.

The resistor R4 connected between the first relay point and the ground may adjust the maximum attenuation of the switching pin diode of the input terminal. The larger the resistance value, the larger the attenuation amount, and the smaller the resistance value, the smaller the attenuation amount.

As described above, the present invention utilizes a pin diode used for input switching in an R.F. automatic gain controller of a two-input type for R.A.attenuation in connection with an R.F.autogain controller. As a result, a wider dynamic range can be obtained than conventional R. auto gain controllers, thereby improving the attenuation and beat characteristics of the strong electric field.

Claims (6)

A first input terminal and a second input terminal to which an RF signal of the tuner is amplified and applied; A third input terminal to which an automatic gain control voltage V _AGC output from the automatic gain control detector is applied; An output terminal for applying the output signal to the second RF amplifier of the tuner; Relay point, A switching first pin diode connected between the first input terminal and the relay point; A switching second pin diode connected between the second input terminal and the relay point; A pin diode for automatic gain control connected between the output terminal and the relay point; A two-input RF gain (RF) automatic gain comprising a transistor and a resistor and having an automatic gain control buffer for buffering and applying the automatic gain control voltage V _AGC input through the third input terminal to the output terminal. In the controller, A transistor having a base end, an emitter end, and a collector end; A first resistor connected between the base end and the third input end; A second resistor connected between the collector terminal and the relay point; A third resistor connected between the emitter and the ground; And a fourth resistor connected between the relay point and the ground. The method of claim 1, wherein the switching first pin diode, A two-input automatic gain controller according to claim 2, wherein two pin diodes are connected in series and a cathode is connected to the relay point. The method of claim 1, wherein the switching second pin diode, Two pin diodes are connected in series, and the cathode is connected to the relay point. Automatic gain controller. According to claim 1, wherein the pin gain for automatic gain control, A two-input automatic gain controller according to claim 2, wherein two pin diodes are connected in series and a cathode is connected to the relay point. The method of claim 1, wherein the relay point, The first input diode for blocking the first pin diode and the negative electrode of the first pin diode and the direct current blocking first capacitor is characterized in that it further comprises connecting the first capacitor for blocking the pin diode. F automatic gain controller. The method of claim 1, wherein the output terminal, An automatic gain controller of two input type, characterized in that it is connected to the input terminal of the second RF amplifier of the tuner through a second capacitor for blocking the DC current.