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Demodulating tuner for converting TV signal into orthogonal amplitude

A TV signal and tuner technology, applied in the tuner field, can solve problems such as inability to compensate input return loss, deterioration of image rejection ratio, local leakage, etc.

Inactive Publication Date: 2003-09-03
SHARP KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, input return loss cannot be compensated over the entire receive band
[0026] (5) In the traditional digital STB tuner of the single conversion system, the local leakage of the local oscillator circuit 25-27 is prone to occur on the CATV signal input terminal 2
As a result, the image rejection ratio deteriorates to a value equal to or greater than -50dBc

Method used

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  • Demodulating tuner for converting TV signal into orthogonal amplitude
  • Demodulating tuner for converting TV signal into orthogonal amplitude
  • Demodulating tuner for converting TV signal into orthogonal amplitude

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Embodiment Construction

[0043] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The same symbols in the drawings represent the same or corresponding components, and their descriptions will not be repeated.

[0044] refer to figure 1 ,and Figure 4 Compared with the conventional digital STB tuner 100 shown in , the digital STB tuner according to the embodiment of the present invention further includes PIN attenuation circuits 30 , 31 and a buffer amplifier 32 .

[0045] The PIN attenuation circuit 30 is connected to the output end of the high-pass filter 5 . The PIN attenuation circuit 31 is connected to the input end of the high frequency amplification input tuning circuit 9-11. The buffer amplifier 32 is connected between the PIN attenuation circuits 30 and 31, and outputs the result.

[0046] The buffer amplifier 32 receives the signal transmitted from the circuit 30 attenuated from the PIN, amplifies it, and outputs the result. ...

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Abstract

A PIN attenuator circuit within a digital STB tuner is connected to an output-side of a high-pass filter, and a PIN attenuator circuit is connected to an input-side of high-frequency amplification input tuning circuits. A buffer amplifier is connected between the PIN attenuator circuits. The PIN attenuator circuits and high-frequency AGC circuits are controlled in common.

Description

technical field [0001] The present invention relates to a tuner, in particular to a tuner for a digital set-top box (set-top box: hereinafter abbreviated as STB) for digital television broadcasting. Background technique [0002] From 1998 to 2000, three types of digital TV broadcasting (terrestrial broadcasting, satellite broadcasting, cable TV broadcasting) appeared. A digital STB is an accessory that goes with a television receiver to receive this digital broadcast. Digital STBs for terrestrial broadcasting, satellite broadcasting, and cable TV broadcasting have a similar structure, and an input stream generally used in digital STBs is MPEG2 (Moving Picture Experts Group 2). [0003] However, front-end circuits, software depending on a CA (Conditional Access) system or a data broadcasting service system, digital interfaces connected to external devices, and the like differ depending on the specific kind of service or provider. [0004] A digital STB tuner may be used in ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03J5/24H04B1/16H04B1/18H04N5/44H04N5/50H04N7/10H04N7/16
CPCH04N21/4263H04N5/50H03J5/244
Inventor 松浦修二
Owner SHARP KK