KR101469635B1 - Circuit for controlling automatic gain of digital intermediate frequency - Google Patents

Abstract

The present invention relates to a digital signal processing apparatus, comprising: a MOPLL IC that receives a digital RF signal and converts the digital RF signal into a digital IF signal and outputs the digital IF signal; filter means for filtering the digital IF signal converted by the MOPLL IC; And a digital demodulation IC for demodulating the digital IF signal filtered by the band pass filter section for digital IF and the digital IF band pass filter section for passing only the digital IF signal amplified by the amplification section Thereby providing an automatic gain control circuit for a digital intermediate frequency.

A band pass filter section for digital IF, a digital IF signal, gain

Description

[0001] The present invention relates to an automatic gain control circuit for a digital intermediate frequency,

An embodiment relates to an automatic gain control circuit for digital intermediate frequency.

In general, an automatic gain control circuit for digital intermediate frequency is provided to adjust the automatic gain to match the intermediate frequency band of the converted digital IF signal.

When the digital IF signal output from the MOPLL IC is filtered by the filter means, the conventional automatic gain control circuit for the digital intermediate frequency amplifies the digital IF signal amplified by the amplifier to compensate for the lost gain, And supplied to a digital demodulation IC for demodulation.

However, in the conventional automatic gain control circuit for the digital intermediate frequency, unnecessary bit components are generated in the process of amplifying the digital IF signal, and the digital IF signal and the unnecessary bit components are mixed and supplied to the digital demodulation IC.

Therefore, the conventional automatic gain control circuit for the intermediate frequency has a problem in that a noise signal is generated due to unnecessary bit components, thereby deteriorating the quality of the reception state.

The automatic gain control circuit for the digital intermediate frequency according to the embodiment allows only the digital IF signal to pass therethrough so that the noise signal can be suppressed and the quality of the reception state can be improved.

An automatic gain control circuit for a digital intermediate frequency according to an embodiment includes a MOPLL IC for receiving a digital RF signal and converting the digital RF signal into a digital IF signal and outputting the digital IF signal, a filter means for filtering the digital IF signal converted by the MOPLL IC, A band-pass filter for a digital IF which passes only the digital IF signal amplified by the amplifier, and a band-pass filter for a digital IF, which is filtered by the band-pass filter for digital IF And a digital demodulation IC for demodulating the digital IF signal.

The automatic gain control circuit for the digital intermediate frequency according to the embodiment allows only the digital IF signal to pass therethrough so that the noise signal can be suppressed and the quality of the reception state can be improved.

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

<Examples>

1 is a block diagram illustrating an automatic gain control circuit for a digital intermediate frequency according to an embodiment of the present invention.

1, an automatic gain control circuit 100 for a digital intermediate frequency according to an embodiment of the present invention includes an MOPLL IC 102, a filter unit 104, an amplification unit 106, a band pass filter Unit 108, a digital demodulation IC 110, and the like.

The MOPLL IC 102 is provided to receive a digital RF signal and convert it into a digital IF signal, and the filter means 104 is provided to filter the digital IF signal converted by the MOPLL IC 102. At this time, the filter means 104 may include a SAW filter.

The amplification unit 106 amplifies the digital IF signal filtered by the filter means 104 to compensate for the lost gain.

At this time, the amplifier 106 may include an amplifier 106a, a first capacitor C1, a second capacitor C2, and the like.

The amplifier 106a may be provided to amplify the digital IF signal filtered by the filter means 104 and the first capacitor C1 may be provided at one end of the input side of the amplifier 106a and at one end of the output side of the filter means 104, And the second capacitor C2 may be electrically connected to the other end of the input side of the amplifier 106a and the other end of the output side of the filter means 104. [

The first capacitor C1 stores the first digital IF signal IF1 among the digital IF signals filtered by the filter means 104 and supplies the first digital IF signal IF1 to one end of the input side of the amplifier 106a, The second digital IF signal IF2 among the digital IF signals filtered by the filter means 104 can be stored and supplied to the other input side of the amplifier 106a.

The digital IF bandpass filter unit 108 is provided to pass only the digital IF signal amplified by the amplification unit 106a and the digital demodulation IC 110 is filtered by the bandpass filter unit 108 for digital IF And demodulate the digital IF signal.

In this case, the digital IF band pass filter unit 108 may include a third capacitor C3, a fourth capacitor C4, a first inductor L1, a fifth capacitor C5, and the like.

The third capacitor C3 may be electrically connected to one end of the output side of the amplifier 106a and the fourth capacitor C4 may be electrically connected to the other end of the output side of the amplifier 106a.

The first inductor L1 may be electrically connected to the third capacitor C3 and the fourth capacitor C4 while the fifth capacitor C5 may be electrically connected in parallel with the first inductor L1. have.

The first inductor L1 and the fifth capacitor C5 in parallel form are designed as a bandpass filter for digital IF to pass only the digital IF signal to generate a resonant frequency corresponding to the digital IF signal, The third and fourth capacitors C3 and C4 store only the filtered and uniformly distributed digital IF signals IF1 and IF2 and supply them to the digital demodulation IC 110. [

That is, for example, when the digital IF signal of the tuner provides 36.17 MHZ, the first inductor L1 of the LC resonant circuit time constant of the digital IF band-pass filter is designed to be 560 nH and the fifth capacitor C5 is designed to be 33 pF And the resonant frequency of the band pass filter for digital IF is about 37.02 MHZ.

Therefore, since the automatic gain control circuit 100 for digital intermediate frequency according to the embodiment of the present invention includes the bandpass filter unit 108 for digital IF, the resonance frequency corresponding to the frequency band of the digital IF signal of the tuner Thereby preventing passage of unnecessary bit components generated when the digital IF signal is amplified and supplying only the digital IF signal to the digital demodulation IC 110. [

Accordingly, the automatic gain control circuit 100 for digital intermediate frequency according to an embodiment of the present invention allows only the digital IF signal to pass therethrough, thereby suppressing the noise signal and improving the quality of the reception state.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, it should be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

1 illustrates an automatic gain control circuit for a digital intermediate frequency according to one embodiment of the present invention.

Description of the Related Art [0002]

100: Automatic gain control circuit for digital intermediate frequency

102: MOPLL IC 104: Filter means

106: Amplification part 106a: Amplifier

108: band-pass filter unit for digital IF 110: digital demodulation IC

Claims (4)

A MOPLL IC for receiving a digital RF signal and converting it into a digital IF signal and outputting the digital IF signal; Filter means for filtering the digital IF signal converted by the MOPLL IC; An amplification unit for amplifying the digital IF signal filtered by the filter unit so as to compensate for the lost gain; A digital IF band-pass filter unit for passing only the digital IF signal amplified by the amplifying unit; And And a digital demodulation IC for demodulating the digital IF signal filtered by the band pass filter section for digital IF, Wherein, An amplifier for amplifying the filtered digital IF signal; A first capacitor electrically connected to one end of the input side of the amplifier and one end of the output side of the filter means; And And a second capacitor electrically connected to the other end of the input side of the amplifier and the other end of the output side of the filter means, Wherein the digital IF band-pass filter unit comprises: A third capacitor electrically connected to one end of the output side of the amplifier; A fourth capacitor electrically connected to the other end of the output side of the amplifier; A first inductor electrically connected to the third capacitor and the fourth capacitor; And And a fifth capacitor electrically connected in parallel with the first inductor. delete delete The method according to claim 1, Wherein the filter means comprises a SAW filter.

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