| 摘要 |
PROBLEM TO BE SOLVED: To provide a BS digital tuner which reduces intermodulation distortion due to interference waves of CS signals. SOLUTION: For CS signals having by far higher levels than BS signals levels in receiving BS digital broadcast signals, a switch of an IF amplifier 101 is turned to a position of an amplifier of 28 dB, thereby raising the output of the BS digital tuner 100. As the result, an AGC circuit 29 controls a variable attenuator 23 so as to drop the BS signal level, thus lowering the level of passing signals to be fed to an RF amplifier 24 and a mixer circuit 25. This lowers the level of input signals to the RF amplifier 24 and the mixer circuit 25, and hence reduces the distortion of received signals caused in these circuits which would cause interference waves. COPYRIGHT: (C)2004,JPO
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