| 摘要 |
PROBLEM TO BE SOLVED: To unnecessitate the supply of any special channel-selecting voltage from the outside to prevent the occurrence of picture quality degradation. SOLUTION: A switching circuit 38 composing of a DC/DC converting circuit is provided in a PLLIC 25, the output of this switching circuit 38 is applied through a charge pump circuit 47 provided with a transistor 39 and a loop filter 31 to a local oscillation circuit 21 for VHF, and this local oscillation circuit and the switching circuit 38 are separated by a power source line or ground pattern. Thus, the supply of the special channel-selecting voltage from the outside is unnecessitated to eliminate the picture quality degradation.
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