KR100335743B1 - Circuit for dividing frequency in receiver - Google Patents

Abstract

The present invention relates to a frequency division circuit of a receiver, wherein in a receiver including a frequency division unit, the frequency division unit passes only signals of a desired band among IF signals output from the tuner unit, and the tuner unit and the SAW filter unit A coupling portion for coupling with; A band pass filter connected between the coupling unit and the VIF SAW filter of the SAW filter unit to attenuate an SIF signal, which is an unnecessary frequency band among IF signals input to the VIF SAW filter, and to pass only the VIF signal; A signal induction unit connected between the tuner unit and the VIF SAW filter and supplying a SIF signal, which is a second-induced signal by the IF signal output from the tuner unit, to the SIF SAW filter of the SAW filter unit; An impedance matching unit for impedance matching the VIF signal output from the band pass filter unit and the SIF signal output from the signal induction unit; And a logic unit for arbitrarily adjusting a required frequency band among the SIF signals output from the frequency division unit under external control and supplying the demodulation unit. Therefore, according to the present invention, the IF signal output from the tuner can be detected by separating the video signal and the audio signal by inductive coupling to prevent attenuation and distortion of the signal.

Description

Frequency division circuit of receiver {CIRCUIT FOR DIVIDING FREQUENCY IN RECEIVER}

The present invention relates to a receiver, and more particularly, to a frequency division circuit of a receiver for preventing attenuation and distortion of a signal by separating and detecting an IF signal output from a tuner into a video signal and an audio signal by inductive coupling. .

In general, a receiver receives an RF signal (radio frequency signal) through an antenna of a tuner, converts it into an IF signal (intermediate frequency signal), detects it, and outputs the video signal and the audio signal separately.

As shown in FIG. 1, the receiver 10 includes a tuner unit 11, a frequency divider 12, a SAW filter unit 13, and a demodulator 16.

The tuner unit 11 is configured to filter an RF signal received through an internal antenna (not shown), mix and amplify an RF signal and a local oscillation signal, and finally output an IF signal.

The frequency divider 12 is composed of L1, C1, C2, C3, and R1 to separate the IF signal supplied from the tuner unit 11. Here, L1, C1, and R1 impedance-match the IF signal output from the tuner unit 11 with the SAW filter unit 13, and C2 and C3 match the IF signal supplied from the tuner unit 11 to each VIF SAW filter. 14 and the SIF SAW filter 15 pass the frequency bands required, that is, the VIF signal and the SIF signal.

The SAW filter unit 13 is composed of a VIF SAW filter 14 and a SIF SAW filter 15 to pass only signals of desired bands from the VIF signal and the SIF signal supplied from the frequency division unit 12.

The demodulator 16 is configured to detect the VIF signal and the SIF signal supplied from the VIF SAW filter 14 and the SIF SAW filter 15 as respective local oscillation signals, and finally output the video and audio signals.

However, since the conventional receiver 10 simply separates the IF signal supplied from the tuner unit 11 in the frequency divider 12, it cannot actually pass the frequency band required by the SAW filter unit 13 to pass it. The attenuation of the signal is a big problem.

In addition, the VIF SAW filter 14 and the SIF SAW filter 15 of the conventional receiver 10 have another problem in that signal distortion occurs due to mutual impedance effects.

In addition, if one of the video band and the audio band is improved, the SIF band and the VIF band, such as a French broadcasting system, have a different problem in that the characteristics of each frequency band are severely changed.

Accordingly, an object of the present invention is to solve the above problems and to prevent attenuation and distortion of a signal by separating and detecting an IF signal output from a tuner into a video signal and an audio signal by inductive coupling.

Another object of the present invention is to enable arbitrary adjustment of a required frequency band by selectively inputting an IF signal to a SIF SAW filter when receiving a special broadcast.

1 is a block circuit diagram showing a conventional receiver

2 is a block circuit diagram illustrating a receiver to which a frequency division circuit according to the present invention is applied.

<Explanation of symbols for main parts of the drawings>

100 receiver 110 tuner unit

120: frequency division unit 121: coupling unit

122: band pass filter unit 123: impedance matching unit

124: logic section 130: SAW filter section

131: VIF SAW filter 132: SIF SAW filter

140: demodulation unit C10, C20: first and second coupling capacitor

C30 to C60: First to Fourth Condenser L10: Coil

R10: resistor VL10: variable coil

Features of the present invention for achieving the above objects,

A tuner unit for converting and receiving the received RF signal into an IF signal, a frequency divider for separating and outputting an IF signal output from the tuner unit into a VIF signal and a SIF signal, and a VIF signal output from the frequency divider; A receiver comprising a SAW filter unit for passing only signals of a desired band among SIF signals, and a demodulation unit for detecting a VIF signal and an SIF signal output from the SAW filter unit and outputting a video signal and an audio signal,

The frequency division unit,

A coupling unit configured to pass only a signal having a desired band among IF signals output from the tuner unit, and to couple the tuner unit and the SAW filter unit;

A band pass filter unit connected between the coupling unit and the VIF SAW filter of the SAW filter unit to attenuate the SIF signal, which is an unnecessary frequency band among IF signals input to the VIF SAW filter, and to pass only the VIF signal;

A signal induction unit connected between the tuner unit and the VIF SAW filter and supplying a SIF signal, which is a second-induced signal by the IF signal output from the tuner unit, to the SIF SAW filter of the SAW filter unit;

An impedance matching unit for impedance matching the VIF signal output from the band pass filter unit and the SIF signal output from the signal induction unit;

And a logic unit for arbitrarily adjusting a required frequency band among the SIF signals output from the frequency division unit according to external control and supplying the demodulation unit.

Herein, the coupling part includes a plurality of coupling capacitors connected in series to the output terminal of the tuner part, respectively.

Here, the band pass filter part may include a first capacitor connected in series to an output terminal of the tuner part, and a coil connected in parallel to a rear end of the first capacitor.

Here, the signal induction part is a variable coil in which a primary coil is connected in parallel to an output terminal of the tuner part, and a secondary coil is connected to the SIF SAW filter side.

Here, the impedance matching unit,

A second capacitor connected in series with the output terminal of the band pass filter;

A third capacitor connected in parallel to a rear end of the second capacitor,

A fourth capacitor connected in series with the output terminal of the signal induction part;

It includes a resistor connected in series to the rear end of the fourth capacitor.

Here, the logic unit,

A power supply stage for supplying power,

A first diode connected in parallel between the fourth capacitor and the first resistor,

A second coil connected in parallel to an output side of the first diode,

A seventh capacitor connected in series with the second coil,

A second diode connected in parallel between the first diode and the first resistor;

A third coil connected in parallel to the output side of the second diode,

An eighth capacitor is connected in series with the third coil.

Hereinafter, the configuration and operation of the frequency division circuit of the receiver according to the present invention will be described in detail with reference to FIG.

2 is a block circuit diagram illustrating a receiver to which a frequency division circuit according to the present invention is applied.

Referring to FIG. 2, the receiver 100 according to the present invention includes a tuner 110, a frequency divider 120, a SAW filter 130, and a demodulator 140.

The tuner unit 110 is configured to filter the RF signal received through an internal antenna (not shown), mix and amplify the RF signal and the local oscillation signal, and finally output the IF signal.

The frequency divider 120 includes a coupling unit 121, a band pass filter unit 122, a variable coil VL10, an impedance matching unit 123, and a logic unit 124.

The coupling unit 121 passes only a signal having a desired band among the IF signals output from the tuner unit 110, and the first coupling capacitor C10 for coupling the tuner unit 110 and the SAW filter unit 130, It consists of a 2nd coupling capacitor C20.

The band pass filter 122 attenuates the SIF signal, which is an unnecessary frequency band among the IF signals input to the VIF SAW filter 131, and is connected to the output terminal of the tuner 110 in series so as to pass only the VIF signal. And a coil L10 connected in parallel at the rear end of the first capacitor C30. Here, the band pass characteristic of the VIF signal may be adjusted by the first capacitor C30 and the coil L10.

The variable coil VL10 has a primary coil to supply the SIF signal, which is a second-induced signal by the IF signal output from the tuner unit 110, to the SIF SAW filter 132 of the SAW filter unit 130. It is connected in parallel to the output terminal of 110, the secondary coil is connected to the SIF SAW filter 132 side. Here, the band pass characteristic of the SIF signal may be adjusted by the secondary coil of the variable coil VL10 and the fourth capacitor C60 described below.

The impedance matching unit 123 is connected in series to an output terminal of the band pass filter unit 122 to impedance-match the VIF signal output from the band pass filter unit 122 and the SIF signal output from the variable coil VL10. A third capacitor C50 connected in parallel to the rear end of the capacitor C40, the second capacitor C40, a fourth capacitor C60 connected in series to the output terminal of the secondary coil of the variable coil VL10, It consists of a resistor (R10) connected in series to the rear end of the four capacitor (C60).

The logic unit 124 is required of the SIF signal that is switched from the secondary side of the variable coil VL10 of the frequency division unit 120 by switching the first diode D10 and the second diode D20 according to external control. A first diode connected in parallel between the fourth capacitor C40 and the first resistor R10 and a power supply terminal B ⁺ for supplying power to the demodulator 140 by selectively adjusting the frequency band. (D10), the second coil (L20) connected in parallel to the output side of the first diode (D10), the seventh capacitor (C70) connected in series to the second coil (L20), and the first diode (D10) A second diode D20 connected in parallel between the first resistor R10, a third coil L30 connected in parallel to an output side of the second diode D20, and a third coil connected in series with the third coil L30. It consists of eight capacitors (C30). Here, R20 is a resistor for supplying a bias voltage to the first diode D10 and the second diode D20. Here, when the control signal A is input to the logic unit 124, the signal is applied only to the cathode of the first diode D10 through the second coil L20, and thus the first diode D10 is not switched. Since only the second diode D20 is switched, only the SIF signal of the desired band is filtered by the third coil L30 and the eighth capacitor C80 through the SIF signal through the second diode D20. ) Is entered. On the contrary, when the control signal B is input to the logic unit 124, the second diode D20 is turned off and the first diode D10 is turned on so that the SIF signal through the first diode D10 is converted to the second coil ( Only the SIF signal of the desired band is input to the SIF SAW filter 132 by the filtering action of the L20 and the seventh capacitor C70.

The SAW filter unit 130 includes a VIF SAW filter 131 and a SIF SAW filter 132 to pass only signals of a desired band among the VIF signal and the SIF signal supplied from the frequency divider 120.

The demodulator 140 is configured to detect the VIF signal and the SIF signal supplied from the VIF SAW filter 131 and the SIF SAW filter 132 as respective local oscillation signals, and finally output the video signal and the audio signal.

Hereinafter, an operation of a receiver to which a frequency division circuit according to the present invention is applied will be described in detail with reference to FIG. 2.

When the IF signal is output from the tuner unit 110, the first coupling capacitor C10 and the second coupling capacitor C20 of the coupling unit 121 pass the IF signal of a predetermined band, and the band pass filter unit 122. ) Passes only the desired VIF signal among the IF signals supplied from the coupling unit 121 and removes unnecessary SIF signals. At this time, the IF signal is applied to the primary coil of the variable coil VL10, and thus the SIF signal is induced to the secondary coil.

The VIF signal output from the band pass filter unit 122 and the SIF signal output from the variable coil VL10 are generated by the respective elements of the impedance matching unit 123. The VIF SAW filter 131 of the SAW filter unit 130 is applied. And the SIF SAW filter 132 and the filters 131 and 132 in impedance matching. At this time, the SIF signal input to the SIF SAW filter 132 is selectively input according to the switching of the logic unit 124.

Then, the VIF SAW filter 131 and the SIF SAW filter 132 of the SAW filter 130 pass only signals of a desired band of the VIF signal and the SIF signal, respectively, and the demodulator 140 includes the VIF SAW filter 131, The VIF signal and the SIF signal supplied from the SIF SAW filter 132 are detected as respective local oscillation signals, and finally the video and audio signals are finally output.

Therefore, since the I-order IF signal output from the tuner unit is supplied to the SAW filter unit without being converted into the secondary IF signal, the signal attenuation due to the output conversion does not occur.

As described above, according to the frequency division circuit of the receiver according to the present invention, it is possible to prevent attenuation and distortion of a signal by separating and detecting an IF signal output from a tuner into a video signal and an audio signal by inductive coupling.

In addition, according to the present invention, in the case of a special broadcast, the IF signal may be selectively input to the SIF SAW filter upon reception, thereby enabling arbitrary adjustment of the required frequency band.

Claims (6)

A tuner unit for converting and receiving the received RF signal into an IF signal, a frequency divider for separating and outputting an IF signal output from the tuner unit into a VIF signal and a SIF signal, and a VIF signal output from the frequency divider; A receiver comprising a SAW filter unit for passing only signals of a desired band among SIF signals, and a demodulation unit for detecting a VIF signal and an SIF signal output from the SAW filter unit and outputting a video signal and an audio signal, The frequency division unit, A coupling unit configured to pass only a signal having a desired band among IF signals output from the tuner unit, and to couple the tuner unit and the SAW filter unit; A band pass filter unit connected between the coupling unit and the VIF SAW filter of the SAW filter unit to attenuate the SIF signal, which is an unnecessary frequency band among IF signals input to the VIF SAW filter, and to pass only the VIF signal; A signal induction unit connected between the tuner unit and the VIF SAW filter and supplying a SIF signal, which is a second-induced signal by the IF signal output from the tuner unit, to the SIF SAW filter of the SAW filter unit; An impedance matching unit for impedance matching the VIF signal output from the band pass filter unit and the SIF signal output from the signal induction unit; And a logic unit which arbitrarily adjusts a required frequency band among the SIF signals output from the frequency division unit and supplies the demodulation unit under external control. The method of claim 1, The coupling part, And a plurality of coupling capacitors connected in series to the output terminal of the tuner unit, respectively. The method of claim 1, The band pass filter unit, And a first capacitor connected in series to an output terminal of the tuner unit, and a coil connected in parallel at a rear end of the first capacitor. The method of claim 1, The signal organic portion, And a primary coil connected in parallel to an output terminal of the tuner unit, and a secondary coil connected to the SIF SAW filter side. The method of claim 1. The impedance matching unit, A second capacitor connected in series with the output terminal of the band pass filter; A third capacitor connected in parallel to a rear end of the second capacitor, A fourth capacitor connected in series with the output terminal of the signal induction part; And a first resistor connected in series with a rear end of the fourth capacitor. The method according to claim 1 or 5, The logic unit, A power supply stage for supplying power, A first diode connected in parallel between the fourth capacitor and the first resistor, A second coil connected in parallel to an output side of the first diode, A seventh capacitor connected in series with the second coil, A second diode connected in parallel between the first diode and the first resistor; A third coil connected in parallel to the output side of the second diode, A frequency division circuit of a receiver comprising an eighth capacitor connected in series with the third coil.