KR100311808B1 - Digital tuner for improving neighboring channel characteristic of low symbol signal - Google Patents

Digital tuner for improving neighboring channel characteristic of low symbol signal Download PDF

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KR100311808B1
KR100311808B1 KR1019970065889A KR19970065889A KR100311808B1 KR 100311808 B1 KR100311808 B1 KR 100311808B1 KR 1019970065889 A KR1019970065889 A KR 1019970065889A KR 19970065889 A KR19970065889 A KR 19970065889A KR 100311808 B1 KR100311808 B1 KR 100311808B1
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South Korea
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signal
intermediate frequency
symbol
amplifier
low
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KR1019970065889A
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Korean (ko)
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KR19990047462A (en
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남창갑
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이형도
삼성전기주식회사
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/06—Arrangements for obtaining constant bandwidth or gain throughout tuning range or ranges
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/28—Continuous tuning of more than one resonant circuit simultaneously, the tuning frequencies of the circuits having a substantially constant difference throughout the tuning range
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
    • H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
    • H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
    • H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/50—Tuning indicators; Automatic tuning control

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Superheterodyne Receivers (AREA)

Abstract

PURPOSE: A digital tuner for improving a neighboring channel characteristic of a low symbol signal is provided to obtain a neighboring channel removal effect in a digital signal of a low symbol as well as a high symbol signal of a wide band by using a low-pass filter and a synchronous circuit. CONSTITUTION: The first RF amplifier portion(21) is used for amplifying an RF input signal. The first automatic gain control portion(22) controls a gain of an output signal of the first RF amplifier portion(21). The second RF amplifier portion(23) is used for amplifying an output signal of the automatic gain control portion(22). A local oscillator(24) is used for oscillating a frequency corresponding to a selected channel. A buffer amplifier portion(25) applies a local oscillation signal of the local oscillator(24) to a mixer portion(26). The mixer portion(26) outputs an IF(Intermediate Frequency) signal from the RF signal of the second RF amplifier portion(23) and the local oscillation signal of the buffer amplifier portion(25). The second automatic gain control portion(27) controls a gain of the IF signal of the mixer portion(26). A synchronous filter portion(28) outputs a center frequency of the IF signal as a resonance frequency. An IF amplifier portion(29) is used for amplifying the IF signal synchronized with the synchronous filter portion(28). An I/Q demodulator portion(30) demodulates the IF signal of the IF amplifier portion(29) to the I and the Q signals. A selection switch portion(31) has the first and the second switches(SW1,SW2). A filter portion(32) is formed with low pass filter circuits(L3,L4,C7,C8)(L5,L6,C10,C11), and condensers(C6,C9). An A/D converter(33) converts the I and the Q signals to digital signals.

Description

로우 심볼 신호의 인접채널제거특성을 개선한 디지탈 튜너Digital Tuner Improves Adjacent Channel Rejection of Low Symbol Signals

본 발명은 선국수신된 고주파신호를 중간주파신호로 변환한후 I/Q신호로 복조하는 디지탈튜너에 관한 것으로, 보다 상세하게는 단간동조필터회로 및 로우패스필터를 이용하여 하이심볼(HIGH SYMBOL) 뿐만아니라 로우심볼(LOW SYMBOL)에서 충분한 인접채널제거비를 갖을 수 있는 로우 심볼 신호의 인접채널제거특성을 개선한 디지탈 튜너에 관한 것이다.The present invention relates to a digital tuner that converts a tuned received high frequency signal into an intermediate frequency signal and demodulates it into an I / Q signal. More particularly, the present invention relates to a high symbol using a short inter-tuning filter circuit and a low pass filter. In addition, the present invention relates to a digital tuner that improves adjacent channel cancellation characteristics of a low symbol signal capable of having a sufficient adjacent channel removal ratio in a low symbol.

도1은 종래의 디지탈튜너를 도시한 블록구성도로써, 종래의 디지탈튜너는 선국수신된 고주파신호(RFIN)를 증폭하는 제1고주파증폭부(1)와, 상기 제1고주파증폭부(1)로부터 출력된 고주파신호의 이득을 일정하게 조절하는 제1자동이득조절부(2)와, 상기 제1자동이득조절부(2)로부터 출력되는 고주파신호를 증폭하는 제2고주파증폭부(3)와, 상기 제2고주파증폭부(3)에 연결되는 로우패스필터(4)와, 선국채널에 따른 국부발진주파수로 발진하는 국부발진부(5)와, 상기 국부발진부(5)의 발진신호를 혼합부(7)로 인가하는 버퍼증폭부(6)와, 상기 저역통과필터(4)를 통해 입력된 고주파신호와 상기 버퍼증폭부(6)를 통해 인가되는 발진신호를 혼합하여 그 차에 해당하는 중간주파신호를 출력하는 혼합부(7)와, 상기 혼합부(7)로부터 출력되는 중간주파신호의 이득을 일정하게 조정하는 제2자동이득조절부(8)와, 상기 제2자동이득조절부(8)로부터 출력되는 중간주파신호를 소정 레벨증폭하는 중간주파 전치증폭부(9)와, 상기 중간주파 전치증폭부(9)로부터 출력된 중간주파신호에서 인접채널신호를 제거하는 쏘(SAW)필터부(10)와, 상기 쏘필터부(10)를 통과한 중간주파신호를 일정 레벨로 증폭하는 중간주파증폭부(11)와, 상기 중간주파증폭부(11)로부터 출력된 중간주파신호를 I, Q신호로 복조하는 I/Q복조부(12)로 이루어진다.FIG. 1 is a block diagram showing a conventional digital tuner, in which a conventional digital tuner includes a first high frequency amplifier 1 for amplifying a pre-received high frequency signal RFIN, and the first high frequency amplifier 1; A first automatic gain control unit 2 which constantly adjusts the gain of the high frequency signal output from the second high frequency signal unit 3 which amplifies the high frequency signal output from the first automatic gain control unit 2, and And a low pass filter (4) connected to the second high frequency amplifier (3), a local oscillator (5) oscillating at a local oscillation frequency according to a tuning channel, and an oscillation signal of the local oscillator (5). (7) a buffer amplifier (6) to be applied, the high frequency signal input through the low pass filter (4) and the oscillation signal applied through the buffer amplifier (6), the intermediate corresponding to the difference The gain of the intermediate frequency signal output from the mixing section 7 and the mixing section 7 for outputting the frequency signal A second automatic gain adjusting section 8 for adjusting the frequency gain, an intermediate frequency preamplifying section 9 for amplifying a predetermined level of the intermediate frequency signal output from the second automatic gain adjusting section 8, and the intermediate frequency preamplifying amplifier. SAW filter unit 10 for removing adjacent channel signals from the intermediate frequency signal outputted from unit 9, and intermediate frequency amplifier for amplifying the intermediate frequency signal passing through the saw filter unit 10 to a predetermined level. And an I / Q demodulation section 12 for demodulating the intermediate frequency signal output from the intermediate frequency amplifier section 11 into I and Q signals.

이와같이, 종래의 디지탈튜너는 혼입된 인접채널의 신호에 의한 간섭현상을 방지하기 위하여, 상기 중간주파신호를 최종적으로 증폭출력하는 중간주파증폭부(11)의 전단에 필터링특성이 우수한 쏘필터부(10)를 구비하여, 인접채널신호를 제거하였다.As described above, the conventional digital tuner includes a saw filter having excellent filtering characteristics at the front end of the intermediate frequency amplifier 11 which finally amplifies and outputs the intermediate frequency signal in order to prevent interference caused by the signals of the adjacent adjacent channels. 10) to remove adjacent channel signals.

그런데, 상기 쏘필터는 그 통과대역이 와이드밴드로 고정되어 있어 로우심볼의 채널신호를 수신하는 경우에는, 인접채널에 대한 감쇄가 이루어지지 않는 문제점이 있었다.However, the saw filter has a problem that the attenuation of the adjacent channel is not achieved when the pass band is fixed to the wide band so that the low-symbol channel signal is received.

또한, 종래의 디지탈튜너는 인접채널신호에 의한 간섭현상을 방지하기 위하여 구비된 쏘필터부에서의 인젝션로스(INJECTION LOSS)를 보상하기 위하여 쏘필터부의 전단에 전치증폭부를 구비시켜야 하며, 이로인하여 신호의 딜레이(DELAY)현상이 발생하는 문제점이 있었다.In addition, the conventional digital tuner should be provided with a preamplifier in front of the saw filter portion to compensate for the injection loss in the saw filter portion to prevent interference caused by adjacent channel signals. There was a problem that caused a delay of DELAY.

본 발명은 상기와 같은 종래의 문제점을 해결하기 위하여 발명된 것으로써, 그 목적은 쏘필터 대신에 단간동조필터회로와 로우패스필터를 이용하여 와이드밴드의 하이심볼 신호 뿐만 아니라 로우심볼의 디지탈신호에서 충분한 인접채널신호 제거효과를 갖을 수 있는 로우 심볼 신호의 인접채널제거특성을 개선한 디지탈 튜너를 제공하는데 있는 것이다.The present invention has been invented to solve the conventional problems as described above, and its object is to provide a wide band high symbol signal as well as a low symbol digital signal by using an inter-stage tuning filter circuit and a low pass filter instead of the saw filter. An object of the present invention is to provide a digital tuner that improves the adjacent channel cancellation characteristic of a low symbol signal that can have a sufficient adjacent channel signal cancellation effect.

상술한 본 발명의 목적을 달성하기 위한 구성수단으로써, 본 발명은 고주파방송신호를 선국하여 중간주파신호로 변환하는 디지탈 튜너에 있어서,As a constitutional means for achieving the above object of the present invention, the present invention provides a digital tuner for tuning a high frequency broadcast signal to convert it into an intermediate frequency signal.

고주파방송신호를 선국하여 증폭하고, 이득조절하는 고주파증폭부 및 이득조절부와,A high frequency amplifier and gain control unit for amplifying and amplifying high frequency broadcast signals and controlling gain;

상기 증폭된 고주파신호를 국부발진신호와 혼합하여 중간주파신호로 변환하는 주파수변환부와,A frequency converter for mixing the amplified high frequency signal with a local oscillation signal and converting the amplified high frequency signal into an intermediate frequency signal;

상기 주파수변환부로부터 출력되는 중간주파신호가 균일한 크기를 갖도록 이득조절하는 자동이득조절부와,An automatic gain control unit for adjusting gain so that the intermediate frequency signal output from the frequency converter has a uniform size;

상기 자동이득조절부의 출력단에 연결되어 중간주파수에 동조하도록 L,C소자로 이루어진 단간동조필터부와,An inter-stage tuning filter unit comprising L and C elements connected to an output terminal of the automatic gain control unit to tune to an intermediate frequency;

상기 단간동조필터부로부터 출력되는 신호를 증폭하는 중간주파증폭부와,An intermediate frequency amplifier for amplifying the signal output from the inter-stage tuning filter;

상기 중간주파증폭부로부터 출력된 중간주파신호를 I신호와 Q신호로 복조하는 I/Q복조부와,An I / Q demodulator for demodulating the intermediate frequency signal output from the intermediate frequency amplifier into an I signal and a Q signal;

상기 I/Q복조부로부터 출력되는 I신호와 Q신호를 그 심볼레이트에 따라서 하이심볼출력단과 로우심볼출력단으로 선택인가하는 제1,2스위치로 이루어진 선택스위칭부와,A selection switching unit comprising first and second switches for selectively applying the I signal and the Q signal output from the I / Q demodulator to the high symbol output terminal and the low symbol output terminal according to the symbol rate thereof;

상기 선택스위칭부의 하이심볼출력단에 연결되는 와이드밴드통과특성을 갖는 콘덴서와, 상기 선택스위칭부의 로우심볼출력단에 연결되며 로우심볼신호의 대역폭에 따른 컷오프특성을 갖도록 L,C구성된 로우패스필터로 이루어진 필터부를 구비한다.A filter having a wide band pass characteristic connected to the high symbol output stage of the selective switching unit, and a low pass filter configured to be connected to the low symbol output stage of the selective switching unit and having a cutoff characteristic according to a bandwidth of a low symbol signal; A part is provided.

도1은 종래 디지탈튜너의 구성을 보이는 블록도이다.1 is a block diagram showing the configuration of a conventional digital tuner.

도2는 본 발명에 의한 디지탈튜너를 도시한 블록구성도이다.2 is a block diagram showing a digital tuner according to the present invention.

도3(A)는 종래 쏘필터의 주파수특성도이고, 도3(B)는 본 발명에 의한 단간동조필터부의 주파수특성도이고, 도3(C)는 필터부의 주파수특성도이다.Fig. 3 (A) is a frequency characteristic diagram of a conventional saw filter, Fig. 3 (B) is a frequency characteristic diagram of an inter-step tuning filter section according to the present invention, and Fig. 3 (C) is a frequency characteristic diagram of a filter section.

*도면의 주요부분에 대한 부호의 설명** Description of the symbols for the main parts of the drawings *

21 : 제1고주파증폭부 22 : 제1자동이득조절부21: first high frequency amplifier 22: first automatic gain control unit

23 : 제2고주파증폭부 24 : 국부발진부23: second high frequency amplification part 24: local oscillation part

25 : 버퍼증폭부 26 : 혼합부25: buffer amplification section 26: mixing section

27 : 제2자동이득조절부 28 : 단간동조필터부27: second automatic gain control unit 28: inter-stage tuning filter

29 : 중간주파증폭부 30 : I/Q복조부29: intermediate frequency amplifier 30: I / Q demodulator

31 : 선택스위칭부 32 : 필터부31: optional switching part 32: filter part

33 : 아날로그디지탈컨버터(ADC)33: analog digital converter (ADC)

이하, 첨부한 도면을 참조하여 본 발명의 구성 및 작용을 상세하게 설명한다.Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the present invention.

도2는 본 발명에 따른 디지탈튜너를 도시한 블록구성도로써, 선국수신된 고주파입력신호(RFIN)를 증폭하는 제1고주파증폭부(21)와, 상기 제1고주파증폭부(21)로부터 출력되는 고주파신호를 일정한 이득으로 조절하는 자동이득조절부(22)와, 상기 자동이득조절부(22)로부터 출력되는 이득조정된 고주파신호를 레벨증폭하는 제2고주파증폭부(23)와, 선국채널에 따른 주파수로 발진하는 국부발진부(24)와, 상기 국부발진부(24)로부터 출력되는 국부발진신호를 혼합부(26)로 인가하는 버퍼증폭부(25)와, 상기 제2고주파증폭부(23)를 통해 입력되는 고주파신호와 버퍼증폭부(25)를 통해 입력되는 국부발진신호를 혼합하여 그 차에 해당하는 중간주파신호를 출력하는 혼합부(26)와, 상기 혼합부(26)로부터 출력되는 중간주파신호의 이득을 일정한 값으로 조정하는 제2자동이득조절부(27)와, 상기 제2자동이득조절부(27)의 출력단에 구비되어 중간주파신호의 중심주파수를 공진주파수로 하도록 콘덴서(C1∼C5) 및 코일(L1,L2)로 설계된 단간동조필터부(28)와, 상기 단간동조필터부(28)에 동조된 중간주파신호를 증폭하는 중간주파증폭부(29)와, 상기 중간주파증폭부(29)로부터 출력되는 중간주파신호를 I,Q신호로 복조하는 I/Q복조부(30)와, 상기 I/Q복조부(30)의 I신호와 Q신호를 각각 수신신호의 심볼레이트(RATE)에 따라서 로우심볼출력단(I1,Q1) 또는 하이심볼출력단(I2,Q2)에 선택인가하는 제1,2선택스위치(SW1,SW2)를 구비한 선택스위칭부(31)와, I신호와 Q신호 로우심볼출력단(I1,Q2)에 연결되는 I신호와 Q신호의 로우패스필터회로(L3,L4,C7,C8), (L5,L6,C10,C11)와 상기 하이심볼출력단(I2,Q2)에 각각 연결되는 와이드밴드통과특성을 갖는 콘덴서(C6,C9)를 구비한 필터부(32)와, 상기 필터부(32)로부터 출력되는 I,Q신호를 디지탈신호로 변환하는 아날로그디지탈컨버터(33)를 구비한다.FIG. 2 is a block diagram showing a digital tuner according to the present invention, which is output from a first high frequency amplifier 21 for amplifying tuned received high frequency input signal RFIN and the first high frequency amplifier 21; An automatic gain adjusting unit 22 for adjusting a high frequency signal to be a constant gain, a second high frequency amplifier 23 for amplifying a gain-adjusted high frequency signal output from the automatic gain adjusting unit 22, and a tuning channel. A local oscillator 24 oscillating at a frequency according to the present invention, a buffer amplifier 25 for applying a local oscillation signal output from the local oscillator 24 to the mixer 26, and the second high frequency amplifier 23 A mixing unit 26 for mixing the high frequency signal inputted through the signal and the local oscillation signal inputted through the buffer amplifier 25 and outputting an intermediate frequency signal corresponding to the difference, and outputting from the mixing unit 26. Second automatic adjustment of the gain of the intermediate frequency signal It is provided between the gain control unit 27 and the output terminal of the second automatic gain control unit 27 and is designed between the capacitors C1 to C5 and the coils L1 and L2 so that the center frequency of the intermediate frequency signal is the resonance frequency. The intermediate frequency signal 29 outputted from the intermediate frequency amplifier 29 and the intermediate frequency amplifier 29 amplifying the intermediate frequency signal tuned to the tuning filter unit 28, the inter-stage tuning filter unit 28, and I. The I / Q demodulator 30 demodulating the Q signal and the I / Q demodulator 30 and the I / Q demodulator 30 according to the symbol rate (RATE) of the received signal, respectively, the low symbol output stages I1 and Q1. Or the selector switch 31 having first and second selector switches SW1 and SW2 for selecting and applying the high symbol output terminals I2 and Q2 to the I signal and Q signal low symbol output terminals I1 and Q2. The low pass filter circuits (L3, L4, C7, C8), (L5, L6, C10, and C11) of the I and Q signals to be connected and the wide band pass characteristics connected to the high symbol output terminals (I2 and Q2), respectively, Capacitors (C6, C9) And a digital filter 33 for converting the I and Q signals output from the filter unit 32 into digital signals.

다음으로, 상술한 구성을 갖는 디지탈튜너의 동작을 설명한다.Next, the operation of the digital tuner having the above-described configuration will be described.

디지탈신호는 아날로그신호에 비하여 비트특성 및 인터퍼런스(INTERFERENCE)특성이 강하기 때문에, 디지탈신호는 선택채널의 신호가 인접채널의 신호와 20dB이상의 크기차가 있으면, 인접채널에 의한 간섭영향을 받지 않는다.Since the digital signal has stronger bit characteristics and INTERFERENCE characteristics than the analog signal, the digital signal is not affected by interference by the adjacent channel if the signal of the selected channel has a magnitude difference of more than 20 dB from the signal of the adjacent channel.

본 발명은 이러한 디지탈신호의 강한 비트특성을 이용한 것으로, 안테나를 통해 선국수신된 고주파입력신호(RFIN)는 제1고주파증폭부(21)와 제1자동이득조절부(22) 및 제2고주파증폭부(23)에 의하여 일정한 레벨로 증폭되어 혼합부(26)로 입력된다. 또한, 국부발진부(24)에서 발진출력된 국부발진신호는 버퍼증폭부(25)를 통해 상기 혼합부(26)로 입력된다. 이에, 혼합부(26)는 입력되는 고주파신호와 국부발진신호를 혼합하여 그 차주파수신호인 중간주파신호를 출력한다. 이 중간주파신호의 주파수는 일정한 값으로 설정되어 있다. 따라서, 상기 국부발진부(24)의 발진주파수가 선국채널에 따라서 달라진다.The present invention uses the strong bit characteristic of such a digital signal, and the high frequency input signal (RFIN) tuned and received through the antenna is the first high frequency amplifier 21, the first automatic gain control unit 22, and the second high frequency amplifier. Amplified to a predetermined level by the unit 23 and input to the mixing unit 26. In addition, the local oscillation signal output from the local oscillator 24 is input to the mixing unit 26 through the buffer amplifier 25. Accordingly, the mixing unit 26 mixes the input high frequency signal and the local oscillation signal and outputs the intermediate frequency signal which is the difference frequency signal. The frequency of this intermediate frequency signal is set to a constant value. Thus, the oscillation frequency of the local oscillator 24 varies according to the tuning channel.

상기와 같이 혼합부(26)로부터 출력된 중간주파신호는 제2자동이득조절부(27)에 의해 균일한 크기를 갖도록 이득조절된 후, 단간동조필터부(28)로 인가된다.As described above, the intermediate frequency signal output from the mixing unit 26 is gain-adjusted to have a uniform size by the second automatic gain adjusting unit 27 and then applied to the inter-stage tuning filter unit 28.

상기 단간동조필터부(28)는 중간주파신호의 중심주파수(fIF)를 공진주파수로 하여 중간주파수신호에 동조한다. 이 단간동조필터부(28)의 주파수특성은 도3(B)에 보인바와 같다.The inter-step tuning filter 28 tunes to the intermediate frequency signal using the center frequency f IF of the intermediate frequency signal as the resonance frequency. The frequency characteristic of this inter-stage tuning filter 28 is as shown in Fig. 3B.

그리고, 상기 단간동조필터부(28)의 출력측에 나타나는 도3(B)와 같은 주파수특성을 갖는 중간주파신호는 중간주파증폭부(29)에 의해 최종 출력레벨로 증폭되어 I/Q복조부(30)로 인가된다. 상기 I/Q복조부(30)은 입력되는 중간주파신호를 I신호와 Q신호로 복조하여 출력한다.The intermediate frequency signal having the frequency characteristic as shown in FIG. 3 (B) appearing on the output side of the step-interval tuning filter 28 is amplified to the final output level by the intermediate frequency amplifier 29 so that the I / Q demodulation unit ( 30). The I / Q demodulator 30 demodulates the input intermediate frequency signal into an I signal and a Q signal and outputs the demodulated signal.

그리고, 선택스위칭부(31)은 선국수신된 채널의 심볼레이트가 하이인 경우에는 상기 I/Q복조부(30)로부터 출력되는 I신호와 Q신호를 각각 하이심볼출력단(I2,Q2)로 인가하고, 선국수신된 채널의 심볼레이트가 로우인 로우심볼신호인경우에는 I/Q복조부(30)로부터 출력되는 I신호와 Q신호를 각각 로우심볼출력단(I1,Q1)에 인가한다.When the symbol rate of the tuned-in / received channel is high, the selection switching unit 31 applies the I and Q signals output from the I / Q demodulator 30 to the high symbol output terminals I2 and Q2, respectively. When the symbol rate of the tuned-in channel is low, the I and Q signals output from the I / Q demodulator 30 are applied to the low symbol output terminals I1 and Q1, respectively.

그리하여, 로우심볼의 I,Q신호는 필터부(32)의 로우패스필터회로(L3, L4, C7, C8), (L5, L6, C10, C11)로 인가되고, 하이심볼의 I,Q신호는 필터부(32)의 와이드밴드 통과특성을 갖는 콘덴서(C6, C9)로 인가된다.Thus, the I and Q signals of the low symbol are applied to the low pass filter circuits L3, L4, C7 and C8 and L5, L6, C10 and C11 of the filter unit 32, and the I and Q signals of the high symbol. Is applied to the capacitors C6 and C9 having the wide band pass characteristic of the filter portion 32.

상기에서, 로우패스필터회로(L3, L4, C7, C8), (L5, L6, C10, C11)는 도3(C)의 35와 같은 주파수특성을 갖는 것으로, 그 컷오프포인트는 로우심볼 신호의 신호대역폭에 따르고, 상기 와이드밴드 통과특성을 갖는 콘덴서(C6,C9)는 도3(C)의 34와 같은 주파수특성을 갖는 것으로, 그 컷오프포인트는 하이심볼 신호의 대역폭에 따른다.In the above, the low pass filter circuits (L3, L4, C7, C8), (L5, L6, C10, C11) have the frequency characteristics as shown in Figure 35 (C), the cutoff point of the low symbol signal According to the signal bandwidth, the capacitors C6 and C9 having the wide band pass characteristics have the frequency characteristics as shown in 34 in FIG. 3C, and the cutoff point depends on the bandwidth of the high symbol signal.

따라서, 하이심볼에 비하여 사용대역폭이 좁은 로우심볼의 신호의 경우는 로우패스필터를 이용하여 인접채널비를 향상시킨다.Therefore, in the case of a low symbol signal having a narrower bandwidth than the high symbol, a low pass filter is used to improve the adjacent channel ratio.

이와같이, 도3(B)와 같은 주파수특성을 갖는 단간동조필터부(28)에서 떨어지는 인접채널제거비는 LC회로로 이루어진 필터부(32)에서 그 심볼레이트에 따라 적절하게 보상된다.In this way, the adjacent channel rejection ratio dropped in the inter-stage tuning filter section 28 having the frequency characteristic as shown in Fig. 3B is properly compensated according to its symbol rate in the filter section 32 made of the LC circuit.

상기와 같이, 필터부(32)에 의해 인접채널 신호가 감쇄된 I신호와 Q신호는 아날로그디지탈컨버터(33)로 인가되어 디지탈신호로 변환된다.As described above, the I and Q signals, in which the adjacent channel signals are attenuated by the filter unit 32, are applied to the analog digital converter 33 and converted into digital signals.

이와같이, 본 발명은 단가가 높은 쏘필터를 구비하지 않고도 L,C소자로 이루어진 단간동조필터회로와 로우패스필터만으로 디지탈신호의 심볼레이트에 따라서 충분한 인접채널제거효과 뿐만 아니라 비용절감효과를 얻을 수 있으며, 또한, 쏘필터 및 그 전단에 구비되는 전치증폭기로 인한 신호 지연 문제를 해결할 수 있는 우수한 효과가 있는 것이다.As described above, the present invention can obtain not only an adjacent channel elimination effect but also a cost reduction effect according to the symbol rate of the digital signal only by the low-pass filter and the inter-stage tuning filter circuit composed of L and C elements without having a high-cost saw filter. In addition, there is an excellent effect that can solve the signal delay problem due to the pre-amplifier provided in the saw filter and its front end.

Claims (1)

고주파방송신호를 선국하여 중간주파신호로 변환하는 디지탈 튜너에 있어서,A digital tuner that tunes high frequency broadcast signals and converts them into intermediate frequency signals. 고주파방송신호를 선국하여 증폭하고, 이득조절하는 고주파증폭부 및 이득조절부와,A high frequency amplifier and gain control unit for amplifying and amplifying high frequency broadcast signals and controlling gain; 상기 증폭된 고주파신호를 국부발진신호와 혼합하여 중간주파신호로 변환하는 주파수변환부와,A frequency converter for mixing the amplified high frequency signal with a local oscillation signal and converting the amplified high frequency signal into an intermediate frequency signal; 상기 주파수변환부로부터 출력되는 중간주파신호가 균일한 크기를 갖도록 이득조절하는 자동이득조절부와,An automatic gain control unit for adjusting gain so that the intermediate frequency signal output from the frequency converter has a uniform size; 상기 자동이득조절부의 출력단에 연결되어 중간주파수에 동조하도록 L,C소자로 이루어진 단간동조필터부와,An inter-stage tuning filter unit comprising L and C elements connected to an output terminal of the automatic gain control unit to tune to an intermediate frequency; 상기 단간동조필터부로부터 출력되는 신호를 증폭하는 중간주파증폭부와,An intermediate frequency amplifier for amplifying the signal output from the inter-stage tuning filter; 상기 중간주파증폭부로부터 출력된 중간주파신호를 I신호와 Q신호로 복조하는 I/Q복조부와,An I / Q demodulator for demodulating the intermediate frequency signal output from the intermediate frequency amplifier into an I signal and a Q signal; 상기 I/Q복조부로부터 출력되는 I신호와 Q신호를 그 심볼레이트에 따라서 하이심볼출력단과 로우심볼출력단으로 선택인가하는 제1,2스위치로 이루어진 선택스위칭부와,A selection switching unit comprising first and second switches for selectively applying the I signal and the Q signal output from the I / Q demodulator to the high symbol output terminal and the low symbol output terminal according to the symbol rate thereof; 상기 선택스위칭부의 하이심볼출력단에 연결되는 와이드밴드통과특성을 갖는 콘덴서와, 상기 선택스위칭부의 로우심볼출력단에 연결되며 로우심볼신호의 대역폭에 따른 컷오프특성을 갖도록 L,C구성된 로우패스필터로 이루어진 필터부를 구비함을 특징을 하는 로우 심볼 신호의 인접채널제거특성을 개선한 디지탈 튜너.A filter having a wide band pass characteristic connected to the high symbol output stage of the selective switching unit, and a low pass filter configured to be connected to the low symbol output stage of the selective switching unit and having a cutoff characteristic according to a bandwidth of a low symbol signal; A digital tuner having an adjacent channel cancellation characteristic of a low symbol signal characterized by having a portion.
KR1019970065889A 1997-12-04 1997-12-04 Digital tuner for improving neighboring channel characteristic of low symbol signal KR100311808B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101765909B1 (en) * 2010-09-17 2017-08-07 엘지이노텍 주식회사 Module for Tuner

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101765909B1 (en) * 2010-09-17 2017-08-07 엘지이노텍 주식회사 Module for Tuner

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