| 摘要 |
PROBLEM TO BE SOLVED: To provide a kind of an IC that a frequency mixer, a local oscillator, and a PLL circuit are built in, which is capable of preventing oscillation signals of receiving systems from interfering with each other and can be more reduced in cost than a case that two kinds of ICs are used. SOLUTION: Integrated circuits 3 and 4 that mixing circuits 33 and 43, local oscillator circuits 31 and 41, and PLL circuits 32 and 42 are integrated are provided respectively to a first and a second receiving system, 1 and 2. The PLL circuits 32 and 42 are each equipped with a function of turning their own power supply ON or OFF. A resonance circuit 13 is connected to the local oscillation circuit 31 of the integrated circuit 3 of the first receiving system 1, and the resonance circuit 13 is also connected to the local oscillation circuit 41 of the integrated circuit 4 of the second receiving system 2. When digital television signals are received, local oscillation signals oscillated by the local oscillation circuits 31 of the integrated circuit 3 of the first receiving system 1 are supplied to the local oscillation circuit 41 of the integrated circuit 4 of the second receiving system 2, and the power supply of the PLL circuit 42 of the integrated circuit 4 provided to the second receiving system 2 is turned OFF. COPYRIGHT: (C)2007,JPO&INPIT
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