KR20080000141A - Analog/digital tuner - Google Patents

Abstract

An analog/digital tuner is provided to prevent noise from being added through a ground. A tuner(21) converts a high-frequency signal received through an antenna into an intermediate-frequency signal of a desired channel. The first saw filter(22) passes only a band of a digital broadcasting frequency from the intermediate-frequency signal. The first amplifier(23) amplifies the digital broadcasting frequency. A digital broadcasting processing module(26) provides digital broadcasting by using the digital broadcasting frequency. The third saw filter(27) passes a band of an analog broadcasting frequency from the digital broadcasting frequency amplified in the first amplifier. An analog demodulator(28) demodulates the analog broadcasting frequency into an audio/video signal to be output.

Description

Analog / Digital Tuner {ANALOG / DIGITAL TUNER}

1 is a block diagram of a conventional analog / digital tuner.

2 is a block diagram of an analog / digital tuner in accordance with an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

21; Tuner 22; First saw filter

23; First amplifier 24; 2nd saw filter

25; Second amplifier 26; Digital demodulation integrated circuit

27; Third saw filter 28; Analog demodulation integrated circuit

C; Capacitor

The present invention relates to an analog / digital tuner.

Generally, a tuner includes a digital tuner for receiving digital broadcasts, an analog tuner for receiving analog broadcasts, and an analog / digital tuner for receiving both analog broadcasts and digital broadcasts. The analog / digital tuner receiving both the analog broadcast and the digital broadcast includes a digital saw (SAW) filter passing only a signal of an input digital broadcast frequency band, and an analog saw (SAW) filter passing only an analog broadcast frequency band. Will be.

In addition, since the digital saw filter and the analog saw filter have different input loss ratios, an amplifier for compensating for the input loss is provided in front of the saw filter.

Therefore, the analog / digital tuner for receiving the conventional analog broadcast frequency and the digital broadcast frequency, as shown in Fig. 1, the tuner 11 for outputting the intermediate frequency of the channel desired for the high frequency signal received through the antenna; Amplifying a first saw filter 12 passing only a band (44 MHz ± 3 MHz) of the digital broadcast frequency at an intermediate frequency output from the tuner 11 and a digital broadcast frequency attenuated by the first saw filter 12. A first saw 13, a second saw filter 14 which passes only a band (44 MHz ± 3 MHz) of the digital broadcast frequency at the digital broadcast frequency amplified and output from the first amplifier 13, and the second The second amplifier 15 amplifies and outputs the digital broadcasting frequency attenuated by the saw filter 14, and the digital broadcasting frequency amplified and output from the second amplifier 15 is demodulated and output into a digital audio / video signal. A digital demodulation integrated circuit 16; A third saw filter (17) for passing only an analog broadcast frequency band (45.75 MHz ± 3 MHz) at a digital broadcast frequency compensated and output from the first amplifier (13); And an analog demodulation integrated circuit 18 for demodulating and outputting the analog broadcast frequency output from the third saw filter 17 into an analog audio / video signal.

The conventional analog / digital tuner configured as described above converts a high frequency signal input from an antenna into an intermediate frequency of a desired channel through the tuner 11 and outputs the intermediate frequency through the first saw filter 12. Passes through only the digital broadcasting frequency band (44 MHz ± 3 MHz) and outputs it, and amplifies through the first amplifier 13 to compensate for the input loss with respect to the digital broadcasting frequency output from the first saw filter 12 and the second saw. The filter 14 is output.

The second saw filter 14 amplifies and outputs the digital broadcasting frequency band, which is amplified and input, through the desired digital broadcasting frequency band (44 MHz ± 3 MHz) to the second amplifier 15, and the second amplifier 15. ) Is compensated for the input loss and output to the digital demodulation integrated circuit 16 to demodulate and output the digital audio / video signal through the digital demodulation integrated circuit 16.

The digital broadcast frequency band (44MHz ± 3MHz) output through the first saw filter 12 and the first amplifier 13 is only the analog broadcast frequency band (45.75MHz ± 3MHz) through the third saw filter 17. By passing it through, the analog demodulation integrated circuit 18 demodulates and outputs the analog audio / video signal.

As described above, in the analog / digital tuner, when the analog broadcast frequency is received, only the analog broadcast frequency is transmitted from the digital broadcast frequency band output from the first saw filter 12 and the first amplifier 13 through the third saw filter 17. By passing through, it increases the adjacent channel disturbance characteristic and decreases.

At this time, the digital broadcast frequency band (44MHz ± 3MHz) output from the first saw filter 12 and input to the third saw filter 17 is an analog broadcast frequency band (45.75MHz ± 3MHz) of the third saw filter 17. Since there is a difference in frequency, there is a problem that the frequency matching is broken, a ghost phenomenon due to the smear (SMEAR) of the analog signal occurs when receiving the analog broadcast frequency.

In addition, since the third saw filter 17 of the analog / digital tuner has two terminals except input and output terminals grounded, noise is introduced through the two grounded terminals when the analog broadcast frequency is received. Due to the incoming noise, there is a problem that affects the reception of the analog broadcast frequency.

The present invention is to compensate for the frequency by matching the frequency when receiving the analog broadcast frequency in the analog / digital tuner.

In addition, the present invention is to block the noise flowing through the ground in the analog / digital tuner.

The present invention provides a tuner for outputting an intermediate frequency of a desired channel for a high frequency signal received through an antenna; A first saw filter passing only a band of a digital broadcast frequency at an intermediate frequency output from the tuner, a first amplifier amplifying the digital broadcast frequency attenuated by the first saw filter, and amplified and output from the first amplifier A digital broadcast processor for providing digital broadcast using a signal for a digital broadcast frequency; A third saw filter for passing only an analog broadcast frequency band at a digital broadcast frequency amplified and output from the first amplifier; An analog demodulation integrated circuit for demodulating and outputting an analog broadcast frequency output from the third saw filter into an analog audio / video signal; The ground terminal of the third saw filter may include matching means for matching an input digital broadcast frequency with an analog broadcast frequency.

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

2 is a block diagram of an analog / digital tuner according to an embodiment of the present invention.

The tuner 21 converts a high frequency signal received from an antenna into an intermediate frequency corresponding to a desired broadcast channel, and outputs the converted high frequency signal. The tuner 21 includes an MPL.

The first saw filter 22 passes through only a band (44 MHz ± 3 MHz) of the digital broadcasting frequency at an intermediate frequency output from the tuner 21 and outputs it.

The first amplifier 23 amplifies and compensates the attenuated digital broadcast frequency output from the first saw filter 22.

The digital broadcast processor, which is a component for providing digital broadcast, includes a second saw filter 24, a second amplifier 25, and a digital demodulation integrated circuit 26.

The second saw filter 24 outputs only the digital broadcasting frequency band (44 MHz ± 3 MHz) at the digital broadcasting frequency amplified by the first amplifier 23 and output.

The second amplifier 25 amplifies and outputs the attenuated frequency of the digital broadcasting frequency output from the second saw filter 24.

The digital demodulation integrated circuit 26 demodulates and outputs the digital broadcasting frequency amplified by the second amplifier 25 into a desired digital audio / video signal.

The third saw filter 27 passes through an analog broadcast frequency band (45.75 MHz ± 3 MHz) at a digital broadcast frequency amplified by the first amplifier 23 and outputs the third saw filter 27. The ground terminal except for the input and output terminals is provided with matching means for matching the digital broadcasting frequency and the analog broadcasting frequency.

The matching means is provided at one of the two ground terminals of the third saw filter 27.

The matching means may be implemented with a capacitor (C).

The matching means is composed of a capacitor (C) having a low capacitance value. Here, if the low capacity value means a value of 1 to 10pF.

The analog demodulation integrated circuit 28 demodulates the analog frequency output from the third saw filter 27 into a desired analog audio / video signal and outputs the demodulated signal.

According to the present invention configured as described above, when receiving an analog broadcast, a high frequency signal input from the antenna is converted into an intermediate frequency of a desired channel through a tuner 21 and outputted, and the outputted intermediate frequency is the first saw filter 22. Pass through only the digital broadcasting frequency band (44MHz ± 3MHz), and through the first amplifier 23 to compensate the input loss for the digital broadcasting frequency output from the first saw filter 22 Will print.

The digital broadcasting frequency band (44 MHz ± 3 MHz) output from the first amplifier 23 passes through the analog broadcasting frequency band (45.75 MHz ± 3 MHz) in the third saw filter 27 and is output to the analog demodulation integrated circuit 28. In this case, the digital broadcasting frequency band input to the third saw filter 27 is a capacitor having a low capacitance value that is a matching means connected to the ground terminal of the third saw filter 27. By matching with the analog broadcast frequency band of the said 3rd filter 27, the analog smear phenomenon by a matching fault is improved.

In addition, by blocking the noise component flowing through the ground, to prevent the ghost phenomenon caused by noise.

As described above, the present invention configures a capacitor in the ground terminal of the third saw filter that passes only the digital broadcasting frequency band when the analog broadcasting frequency is received by the analog / digital tuner. By passing through to match the analog broadcast frequency band with the capacitor to improve the smear phenomenon of the analog signal due to the frequency difference, and also to block the noise flowing through the ground terminal to prevent the ghost phenomenon caused by noise You can do it.

Claims (4)

A tuner for outputting an intermediate frequency of a channel for which a high frequency signal received through an antenna is desired; A first saw filter passing only a band of a digital broadcast frequency at an intermediate frequency output from the tuner, a first amplifier amplifying the digital broadcast frequency attenuated by the first saw filter, and amplified and output from the first amplifier A digital broadcast processor for providing digital broadcast using a signal for a digital broadcast frequency; A third saw filter for passing only an analog broadcast frequency band at a digital broadcast frequency amplified and output from the first amplifier; An analog demodulation integrated circuit for demodulating and outputting an analog broadcast frequency output from the third saw filter into an analog audio / video signal; And a matching means for matching an input digital broadcast frequency and an analog broadcast frequency to a ground terminal of the third saw filter. The method of claim 1, The matching means is an analog / digital tuner, characterized in that provided on any one ground terminal of the two ground terminals of the third saw filter. The method of claim 1, And said matching means comprises a capacitor. The method of claim 1, Said matching means comprises a capacitor having a value of 1 to 10 pF.

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