KR20060081138A - Frequency selecting type tuner - Google Patents

Abstract

The present invention provides a frequency selective tuning circuit so as to simplify the tuning circuit so that two frequency bands can be selectively tuned.

In order to achieve the above object, the present invention includes an input tuning circuit and a double tuning circuit for selectively tuning an FM signal and a VHF low signal, and the input tuning circuit and the double tuning circuit have a number of diodes and inductors occupying a volume in the circuit. The circuit configuration which minimizes is disclosed.

Input Tuning, Double Tuning, Inductor, FM, VHF Low

Description

Frequency selecting type tuner

1 is a block diagram illustrating a general multimedia receiver.

2 is an input tuning circuit diagram varied by a conventional selection signal.

3 is a double-tuning circuit which is variable by a conventional selection signal.

4 is an equivalent circuit diagram when the FM selection signal voltage is applied to the conventional double-tuning circuit.

Fig. 5 is a circuit diagram showing one embodiment of the input tuning circuit of the present invention.

6 is a circuit diagram showing an embodiment of the double-tuning circuit of the present invention.

The present invention relates to a frequency selective tuning circuit.

The antenna of the multimedia AUDIO / VIDEO device receives various high frequencies having UHF, VHF high, VHF low, and FM frequency bands. These high frequency signals are input tuned by an input tuning circuit passing through each frequency band. However, in order to simplify the circuit, the input copper circuits for VHF high and VHF low can be configured as one, and they can be used variably according to the selection signal, and they can be configured as one system for the VHF low and FM signals having similar frequency bands. It can be optionally changed and used.

1 is a block diagram illustrating a general multimedia receiver.

The block diagram shown in FIG. 1 shows that the VHF low and FM frequency bands can be selected by a single tuning circuit, and the antenna ANT1 receives the high frequency signals of the UHF, VHF high and VHF low bands so that the filter can be selected. The signal is input to the input tuning circuit 3 via (1) and the signal received through the antenna ANT2 is input to the input tuning circuit 3 via the filter 2. The input tuning circuit 3 receives a selection signal for selecting whether to tune the VHF low signal or the FM signal to form a corresponding tuning circuit, and the VHF low signal or the FM signal tuned in the input tuning circuit is a high frequency signal. Amplified by the amplifier 4 and input to the double tuner (5). At this time, the double tuner 5 also double-tunes the VHF low signal or the FM signal according to the selection signal. The double-tuned VHF low signal or FM signal is double-modulated by the oscillation frequency oscillated by the local oscillator 7 in the mixer 6 and then modulated through the filters and amplifiers that follow. (demodulating)

2 is an input tuning circuit diagram variable by a conventional selection signal, and FIG. 3 is a double tuning circuit diagram variable by a conventional selection signal.

When the high signal is input to the FM selection terminal in the input tuning circuit shown in Fig. 2, the diodes D1 and D2 are in a conducting state, and the diodes D3 and D4 are in a non-conducting state, and the FM RF signal is determined by the circuit elements. Resonance is caused by the RF output terminal. In addition, when the selection signal is input to the VHF LOW selection terminal, the diodes D3 and D4 are in a conductive state, but the diodes D1 and D2 are not in the state, and the VHF LOW RF signal is resonated by the resonance frequency determined by the circuit element. It is output to the terminal.

However, in this circuit configuration, the diodes are switching diodes, so the size of the device is large.

In addition, in the double-tuning circuit shown in FIG. 3, the capacitor C ₁ , the diode D ₅ , and the resistor R ₆ are sequentially connected in series between the RF input / output signal terminal and the RF output signal terminal, and the connection point of the D ₅ and R ₆ and the RF signal are sequentially connected. D ₇ and D ₈ are connected in the reverse direction between the output terminals of. Further, C ₂ is connected between the connection point of D ₅ and R ₆ and the ground. In addition, the resonant frequency changing unit 10 for changing the resonant frequency according to the FM selection and the VHF low selection is connected between the connection point of the capacitor C ₁ and the diode D _{5 and} the connection point of the diodes D ₇ and D ₈ . At this time, the resonance frequency shift unit 10, a capacitor C ₁ and diode D ₅ resistor R ₇ and the inductor L _1, L _2, diode connected between the connection point and the ground of D _7, an inductor coupled between the connection point and the ground of the D ₈ L _4, It consists of a capacitor C ₃ connected between the connection point L ₃ and the inductor L ₁ , L _{2 and the} connection point of the inductor L ₄ , L ₃ , and a capacitor C ₄ and diode D ₆ connected between the inductor L ₁ , L ₂ connection point and the ground. The FM selection signal voltage is applied to the connection point through the resistor R ₅ , and when the FM selection signal voltage is not applied, VHF Low selection is made.

When the FM selection signal voltage is not applied to the resistor R ₅ , that is, when the VHF low signal is selected, the resonant frequency of the diode D ₆ is not shown in the resonant frequency converter 10. The resonance is determined by the circuit element, but when the FM selection signal voltage is applied to the resistor R ₅ , the diode D ₆ becomes conductive and the capacitors C ₃ and C ₄ have extremely low resistance to the RF signal. An equivalent circuit for the signal is formed as shown in FIG. Therefore, a change in the resonant frequency to be synchronized when selecting the VHF low signal and selecting the FM signal occurs.

However, this double-tuning circuit has a problem that the volume becomes large because four bulky inductors made of coils are used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and to provide a tuning circuit having excellent tuning performance and a small circuit element used to reduce volume.

A feature of the present invention for achieving the above object is an input tuning circuit for input tuning the RF signal input through the FM signal filter and the VHF Low signal filter and for demodulating the RF signal output through the input tuning circuit. Applied to a frequency selective tuning circuit comprising a double tuning circuit, the input tuning circuit includes an FM signal selection voltage terminal, a VHF low selection voltage terminal, an FM signal input terminal, a VHF low signal input terminal, and an RF output terminal for outputting an FM signal and a VHF low signal. A first diode is connected to the FM signal input terminal and the RF output terminal, and an FM signal selection voltage is applied to the anode of the first diode, and an inductor, a resistor, and a first voltage are output from the VHF low selection voltage terminal to the RF output terminal. Two diodes are sequentially connected, and the VHF low signal is input to the anode of the second diode.

Further, another feature of the present invention is an input tuning circuit for input tuning an RF signal input through an FM signal filter and a VHF low signal filter and a double tuning circuit for demodulating an RF signal output through the input tuning circuit. It is applied to a frequency selective tuning circuit, wherein the double-tuning circuit alternatively uses a VHF Low signal, an RF signal input terminal for inputting an FM signal, a VHF Low signal, an RF signal output terminal for outputting an FM signal, a VHF Low signal and an FM signal. A selector for applying a voltage for selection, and a capacitor, a third diode, and a first resistor are sequentially connected in series from the RF signal input terminal to the RF signal output terminal, and the connection point between the third diode and the first resistor and the RF A fourth diode and a fifth diode are connected by an anode to the signal output terminal in parallel with the first resistor, and the junction point of the capacitor and the third diode is different from the fourth diode. The first inductor, the first resistor, the second resistor and the second inductor are sequentially connected between the connection point of the ion and the fifth diode, and the third interduct is connected and grounded to the connection point of the first resistor and the second resistor. The connection point of the first resistor and the second resistor is connected to the selection terminal through a first capacitor and a third resistor, and between the connection point of the first capacitor and the third resistor and ground by an FM signal selection voltage applied to the selection terminal. The sixth diode to be connected is connected.

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

Fig. 5 is a circuit diagram showing one embodiment of the input tuning circuit of the present invention.                     

The input tuning circuit consists of four input / output terminals: FM signal selection voltage stage (FM band selection), VHF low selection voltage stage (VHF Low selection), FM signal input stage (FM), VHF Low signal input stage (VHF Low) and FM signal. An RF output terminal (RF OUT) for outputting a VHF low signal is provided, and a diode D ₁₂ is connected to the FM signal input terminal and the RF output terminal, an FM signal selection voltage is applied to the anode of the diode D ₁₂ , and a VHF low selection voltage terminal is provided. The inductor L ₁₁ , resistor R ₁₃ and diode D ₁₁ are sequentially connected from the RF output terminal to the RF output terminal, and the VHF low signal is input to the anode of the diode D ₁₁ .

When the selection voltage is applied to the FM selection signal in the input tuning circuit of this configuration, the diode D ₁₁ is turned off and the diode D ₁₂ is turned on so that the FM signal is output to the RF output and VHF Low is selected. When voltage is applied to the signal terminal, the diode D ₁₁ becomes conductive and the diode D ₁₂ becomes non-active so that the VHF Low signal is output from the RF output terminal.

6 is a circuit diagram showing an embodiment of the double-tuning circuit of the present invention.

As shown in the circuit of FIG. 6, the demodulation circuit includes a VHF low signal, an RF signal input terminal (demodulation demodulation input) to which an FM signal is input, a VHF low signal, an RF signal output terminal (demodulation demodulation output) to output an FM signal, and a VHF. And a selection stage (FM band selection) for applying a voltage for alternatively selecting a low signal and an FM signal. The capacitor C ₂₁ , diode D ₂₃ , and resistor R ₂₃ are connected in series from the RF signal input terminal to the RF signal output terminal, and the diode D is connected in parallel with the resistor R ₂₃ between the connection point of the diode D ₂₃ and the resistor R ₂₃ and the RF signal output terminal. _An anode of ₂₂ and diode D ₂₂ is connected and connected, and inductor L ₂₁ , resistor R ₂₁ , resistor R ₂₂ and inductor L ₂₃ are connected between the connection point of capacitor C ₂₁ and diode D _{23 and} the connection point of diode D ₂₂ and diode D ₂₂ . are sequentially connected in series, the connection point of the resistors R ₂₁ and resistor R ₂₂ is is grounded is inter virtue L ₂₂ is connected, and, a resistor R ₂₁ and the resistor FM selection signal connection point of the R ₂₂ is through a capacitor C ₂₂ and resistor R ₂₃ A voltage is applied and a conductive diode D ₂₄ is connected between capacitor C ₂₂ , resistor R ₂₃ and ground. In addition, a ripple suppression capacitor C ₂₃ is connected between the connection point of the diode D ₂₃ and the resistor R _{23 to} ground.

When the FM signal selection voltage is not applied to the RF signal input terminal in the double demodulation circuit having the above configuration, the operation is performed by VHF low signal selection, and in this case, the diode D ₂₄ is turned off. However, when the FM signal selection voltage is applied, the diode D ₂₄ is in a conductive state, and the capacitor C ₂₂ is operated at low impedance, resulting in an equivalent circuit as shown in FIG. 4.

In the present invention having the above object and configuration, the input tuning circuit has a circuit configuration in which two diodes are reduced compared to the conventional circuit configuration, thereby miniaturizing the circuit, and in this case, selecting a device having excellent performance in blocking diodes, It is possible to construct a circuit excellent in terms of performance and size, and the double-tuning circuit can reduce the number of inductors by one than the conventional circuit configuration, thereby making it possible to construct a more compact tuning circuit.

Claims (2)

It is applied to a frequency selective tuning circuit comprising an input tuning circuit for input tuning an RF signal input through an FM signal filter and a VHF low signal filter and a double tuning circuit for demodulating an RF signal output through the input tuning circuit. , The input tuning circuit includes an FM signal selection voltage terminal, a VHF low selection voltage terminal, an FM signal input terminal, a VHF low signal input terminal, and an RF output terminal for outputting an FM signal and a VHF low signal. One diode is connected, an FM signal selection voltage is applied to the anode of the first diode, an inductor, a resistor and a second diode are sequentially connected from the VHF low selection voltage terminal to the RF output terminal, and the anode of the second diode is connected. Frequency-selective tuning circuit, characterized in that the VHF Low signal is input to the wood. It is applied to a frequency selective tuning circuit comprising an input tuning circuit for input tuning an RF signal input through an FM signal filter and a VHF low signal filter and a double tuning circuit for demodulating an RF signal output through the input tuning circuit. , The double-tuning circuit is selected to apply a voltage for selectively selecting a VHF Low signal, an RF signal input terminal for inputting an FM signal, a VHF Low signal, an RF signal output terminal for outputting an FM signal, and a VHF Low signal and an FM signal. And a capacitor, a third diode, and a first resistor are sequentially connected in series from the RF signal input terminal to the RF signal output terminal, and in parallel with the first resistor between the connection point of the third diode and the first resistor and the RF signal output terminal. The fourth diode and the fifth diode are connected by the anode, and the first inductor, the second resistor, the third resistor, and the second diode are connected between the connection point of the capacitor and the third diode and the connection point of the fourth and fifth diodes. Inductors are sequentially connected in series, and a third interduct is connected and grounded at a connection point of the second resistor and the third resistor, and a first capacitor is connected at the connection point of the second resistor and the third resistor. And a sixth diode connected to the selection terminal through a fourth resistor, and connected between the connection point of the first capacitor and the fourth resistor and the ground, the sixth diode connected by the FM signal selection voltage applied to the selection terminal. As your inquiry.

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