KR20070047486A - Tuner - Google Patents

Abstract

The present invention provides an RF amplifier for amplifying an RF signal received through an antenna; A low pass filter (LPF) unit for filtering the harmonics introduced into the RF signal to suppress bit generation; An intermediate signal processing unit for mixing the RF signal with an oscillation frequency and outputting the intermediate signal and filtering and amplifying the intermediate signal corresponding to the set channel; And a demodulator for demodulating the amplified intermediate signal into a digital signal, and detecting a signal strength to transmit a gain control signal.

LPF (Low Pass Filter), Tuner, Harmonics

Description

Tuner {tuner}

1 is a block diagram schematically showing a tuner used in a conventional terrestrial broadcasting system.

FIG. 2 is a block diagram schematically illustrating a double conversion type tuner having a low pass filter (LPF) unit according to the present invention; FIG.

3 is a circuit diagram showing an LPF provided according to the present invention.

* Explanation of symbols for main parts of drawings *

100: antenna 200: tuner

210: RF amplifier 220: tracking filter

230: LPF (Low Pass Filter) unit 231: first inductor

232: first capacitor 233: second inductor

234: second capacitor 240: first intermediate signal processor

241,251: mixer 242,252: oscillator

243,253: phase synchronization circuit 244,254: IF filter

250: second intermediate signal processor 260: IF amplifier

270: demodulator

The present invention relates to a tuner, and more particularly, to a tuner that removes harmonics of each oscillator to prevent bit generation.

In general, the terrestrial digital television tuner is a reception tuner that can receive digital satellite broadcasting directly on a television without going through a satellite relay station. It can solve high-definition, high fidelity and voice broadcasting as well as high-definition digital TV (HDTV). ) Is a core component that enables simultaneous viewing of a wide range of regions. The tuner includes a single conversion type for outputting an intermediate frequency, a double conversion type for amplifying and mixing a primary intermediate frequency signal, and converting the signal into a secondary intermediate frequency for detection. There is this.

As shown in FIG. 1, the conventional tuner 20 includes a band pass filter 21, a low noise amplifier 22, a synchronization processor 23, an intermediate signal processor 24, and a demodulator (see FIG. 1). 25).

The band pass filter 21 selects and filters only a high frequency (RF) signal corresponding to a broadcast band region, and the low noise amplifier 22 suppresses noise components to amplify the selected RF signal.

The synchronization processor 23 has two oscillators therein, two mixers (Mix) connected to each oscillator to amplify and mix the first intermediate frequency signal and the second intermediate frequency, and the first intermediate frequency signal and the secondary. It is composed of a filter unit for each of the intermediate frequencies to tune the RF signal corresponding to the selected channel to generate an intermediate frequency signal, the intermediate signal processor 24 performs the function of filtering / amplifying the intermediate frequency signal.

The demodulator 25 decodes the intermediate frequency signal as a baseband signal to generate audio / video data. The demodulator 25 senses the strength of the intermediate frequency signal and transfers a gain control signal to the intermediate signal processor 24 and the synchronization processor 23. To pass.

That is, the demodulator 25 transmits an RF gain control (RF AGC) signal to the synchronization processor 23 and an IF gain control (IF AGC) signal to the intermediate signal processor 24 to adjust the power of each signal. do.

In such a conventional tuner, harmonics generated at each oscillator of the synchronization processor 23 are reflected from the ground or the connection line, and are introduced into the peripheral portion of the band pass filter 21 or the mixer as a disturbance signal, and thus the performance of the tuner output. Worsens.

An object of the present invention is to solve the problem that the tuner output performance is deteriorated by harmonics, which is a disadvantage of the conventional tuner.

Another object of the present invention is to improve the reliability of the tuner by providing a tuner to remove the adverse effects of harmonics.

The present invention for achieving the above object is an RF amplifier for amplifying the RF signal received through the antenna; A low pass filter (LPF) unit for filtering the harmonics introduced into the RF signal to suppress bit generation; An intermediate signal processing unit for mixing the RF signal with an oscillation frequency and outputting the intermediate signal and filtering and amplifying the intermediate signal corresponding to the set channel; And a demodulator for demodulating the amplified intermediate signal into a digital signal, and detecting a signal strength to transmit a gain control signal.

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

2 is a block diagram schematically illustrating the components of a double conversion tuner (hereinafter referred to as "tuner according to the present invention") 200 having a low pass filter (LPF) according to the present invention. In the description, the tuner according to the present invention is applied to a terrestrial broadcast (OFDM or VSB) reception system.

However, the tuner according to the present invention is not limited to the double conversion type tuner but is also applied to the single conversion type tuner, and of course, it can be applied not only to the terrestrial broadcasting receiving system but also to other receiving systems such as the DBS system.

For reference, DBS (Direct Broadcasting Satellite) refers to a broadcast service that sends a radio wave directly to a terrestrial reception system using a broadcast satellite, and usually receives a radio wave with a small parabolic antenna dedicated to satellite broadcast reception.

Therefore, the tuner 200 according to the present invention processes the RF signal of the 48MHz to 860MHz band.

Referring to FIG. 2, the tuner 200 according to the present invention includes an RF amplifier 210, a tracking filter 220, a low pass filter (LPF) unit 230, and a first intermediate signal processing unit connected to the antenna 100. 240, a second intermediate signal processor 250, an IF amplifier 260, and a demodulator 270.

As the antenna 100, a reflector antenna or a flat antenna using a microstrip line is preferably used. The reflector antenna or flat panel antenna has high gain characteristics and circular polarization characteristics (broadcast signal has circular polarization characteristics), and has to be provided in each receiving system, so that the size is small, inexpensive, and easy to install.

The RF amplifier 210 amplifies the RF signal of the terrestrial broadcast band received through the antenna 100. The RF amplifier 210 may amplify the power to a value of 10 dB or less or recently, between 15 dB and 20 dB in order to realize the best reception sensitivity.

The tracking filter 220 removes noise components included in the RF signal (as a high frequency signal) of the terrestrial broadcast band and filters only the corresponding RF signal.

The LPF unit 230 is a harmonic generated from the oscillator (241, 261) is reflected from the ground or connecting line is introduced into the peripheral portion of the RF amplifier 210, IF amplifier 260 or mixer 241 as a disturbance signal This harmonic is filtered to prevent performance degradation.

The first intermediate signal processor 240 includes a mixer 241, an oscillator 242, a phase synchronization circuit 243, and an IF filter 244. The second intermediate signal processor 250 includes a mixer 251, An oscillator 252, a phase synchronization circuit 253, and an IF filter 254.

The mixer 241 mixes the RF signal passing through the LPF unit 230 with the oscillation frequency input from the oscillator 242 and outputs it as an intermediate frequency signal (hereinafter referred to as an "IF signal"), and the mixer 251. The IF signal passed through the IF filter 244 is mixed again with the oscillation frequency input from the oscillator 252 to output an accurate IF signal.

The oscillators 242 and 252 generate predetermined oscillation frequencies according to external control voltages when channel tuning, respectively, and transmit them to the mixers 241 and 251 individually.

The phase synchronization circuits 243 and 253 synchronize and convert a channel input by a user into a corresponding frequency signal, and transfer the control voltage according to the oscillators 242 and 252, respectively.

The IF filters 244 and 254 respectively remove noise components of the IF signal to filter and output only the corresponding IF signal components, and the IF amplifier 260 amplifies the IF signal to a size that can be processed by the demodulator 270.

The demodulator 270 demodulates the synchronized satellite signal by an Orthogonal Frequency DeModulation (OFDM) scheme or a VSB (Vestigial Side Band) scheme to generate transport stream (TS) data. In addition, when demodulating the satellite signal, the demodulator 270 senses the strength of the IF signal to generate a gain control signal, and transmits the gain control signal to the IF amplifier 260 and the phase synchronization circuits 243 and 253. To adjust it.

In this case, the IF gain control signal IF AGC is transmitted to the IF amplifier 260, and the RF gain control signal RF AGC is transmitted to the phase synchronization circuits 243 and 253.

Since the harmonics generated in the oscillators 242 and 252 are filtered by the LPF unit 230 in the tuner 200 according to the present invention configured as described above, the harmonics cannot be introduced into the peripheral portions such as the mixers 241 and 251. There is no beat in the output of each part, including).

Hereinafter, the LPF unit 230 provided in the tuner 200 according to the present invention will be described.

3 is a circuit diagram showing an LPF unit provided according to the present invention.

As shown in FIG. 3, the LPF unit 230 provided in the tuner 200 according to the present invention includes a first inductor 231, a second inductor 233, a first capacitor 232, and a second capacitor. 234, the first inductor 231 is connected to the output terminal of the tracking filter 220, and the second inductor 233 and the second capacitor 234 are configured in parallel with the LC tank and the first capacitor 232. Are connected in parallel.

One side of the first capacitor 232 is connected to the ground terminal G, and the first inductor 231, the second inductor 233, and the second capacitor 234 are connected in parallel to the LC tank configured in parallel.

The first inductor 231 and the first capacitor 232 pass a low frequency signal among the frequency signals output from the tracking filter 220 and send a high frequency signal through the ground, and the second inductor 233 and the second capacitor 234. ) Is connected in parallel to the LC tank and outputs only the RF signal corresponding to the frequency band signal to the mixer 241 by cutting off signals other than the corresponding frequency signal, specifically, harmonics generated from the oscillators 242 and 252.

Accordingly, since the harmonics are not introduced into the mixer 241 by the LPF unit provided according to the present invention, a bit does not occur in the corresponding frequency band signal, thereby providing a tuner having improved reception performance.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiments are for the purpose of description and not of limitation.

In addition, those skilled in the art will understand that various implementations are possible within the scope of the technical idea of the present invention.

As described above, the present invention does not introduce harmonics into the peripheral portion by the provided LPF unit, and thus, a bit does not occur in the corresponding frequency band signal, thereby providing a tuner having improved reception performance.

Claims (5)

An RF amplifier for amplifying the RF signal received through the antenna; A low pass filter (LPF) unit for filtering the harmonics introduced into the RF signal to suppress bit generation; An intermediate signal processing unit for mixing the RF signal with an oscillation frequency and outputting the intermediate signal and filtering and amplifying the intermediate signal corresponding to the set channel; And And a demodulator for demodulating the amplified intermediate signal into a digital signal, and detecting a signal strength to transmit a gain control signal. The method of claim 1, The LPF unit is located between the RF amplifier and the intermediate signal processing unit, the tuner, characterized in that to prevent the introduction of harmonics of the oscillation frequency of the intermediate signal processing unit. The method of claim 1, The intermediate signal processor is a tuner, characterized in that it comprises a mixer, a phase synchronization circuit, and an intermediate frequency filter. The method of claim 1, The intermediate signal processor comprises: a first intermediate signal processor comprising a first mixer, a first phase synchronization circuit, and a first intermediate frequency filter; And a second intermediate signal processing unit including a second mixer, a second phase synchronization circuit, and a second intermediate frequency filter. The method of claim 1, The LPF unit includes a first inductor, a first capacitor connected in parallel with the first inductor and grounded, and a second inductor and a second capacitor connected in parallel with the first inductor and the first capacitor to form an LC tank. Featured tuner.

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