Input circuit of TV tuner

It is an object of the present invention to provide an input circuit of a TV tuner without causing unnecessary attenuation within a VHF high band bandwidth and without worsening performance such as NF, input sensitivity, and S/N when receiving a VHF high band signal. The input circuit of a TV tuner...

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Bibliographische Detailangaben
Hauptverfasser:	YAMAMOTO MASAKI, FURUTA TOSHIRO
Format:	Patent
Sprache:	eng
Schlagworte:	BASIC ELECTRONIC CIRCUITRY ELECTRIC COMMUNICATION TECHNIQUE ELECTRICITY PICTORIAL COMMUNICATION, e.g. TELEVISION SELECTING RESONANT CIRCUITS TRANSMISSION TUNING RESONANT CIRCUITS
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Beschreibung
Zusammenfassung:	It is an object of the present invention to provide an input circuit of a TV tuner without causing unnecessary attenuation within a VHF high band bandwidth and without worsening performance such as NF, input sensitivity, and S/N when receiving a VHF high band signal. The input circuit of a TV tuner is provided with a parallel resonance circuit and an input tuning circuit connected to an output of the resonance circuit, a varactor diode is provided in parallel with the parallel resonance circuit, and a resonance frequency of a parallel connecting circuit connecting in parallel the parallel resonance circuit with the varactor diode in a nonconductive state is set to a frequency of an FM broadcasting band. Further, a capacitance value of a capacitor is set such that a resonance frequency of a parallel connecting circuit connecting in parallel a second inductor in a conductive state of the varactor diode with the parallel resonance circuit constitutes a frequency higher than the VHF high band bandwidth.