| 摘要 |
<P>PROBLEM TO BE SOLVED: To optimize a DC voltage/current applied to a switching element provided to an input stage of one antenna input circuit in accordance with a field strength, and to prevent the generation of distortion in the switching element when an intense electric field is input. Ž<P>SOLUTION: In the input circuit of a television tuner, a VHF antenna input circuit 60 and a UHF antenna input circuit 30 are connected in parallel to an input terminal T1, and an AGC circuit 40 constituted of an AGC amplifier is connected to an output stage of the VHF antenna input circuit 60 and a UHF antenna input circuit 90. A diode D1 is connected between the input terminal T1 and the UHF antenna circuit 90. A switching element is DC-connected between an input end of the AGC amplifier 41 and an input end of the AGC amplifier 42. A bias voltage is applied to the diode D1 from an input end of the AGC amplifier in a side selected as a receiving band. An input end of the AGC amplifier at a side which is not selected as a receiving band is DC-grounded. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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