TV Ju - Na and its television Ju - television receiver with a Na

摘要

PROBLEM TO BE SOLVED: To reduce the degradation of S/N and to eliminate the need for the expansion of the dynamic range of a high-frequency amplifier circuit by increasing the gain of an intermediate frequency(IF) amplifier circuit at the reception time of specified channel, when the gain of a tuner part is decreased in comparison with the reception time of the other channel. ;SOLUTION: The band data of tuning data DA are set to an idle terminal Te among the band switching voltage terminals of a PLL 17, as well so as to have the same voltage appear as respective band-switching voltage terminals Tvl, Tvh and Tu. For example, when reducing the gain of the tuner part 1 because of a channel W of the UHF band, the same voltage is respectively generated at band-switching voltage terminals Tu and Te of the PLL 17 by combining the tuning data and channel data. Then, the voltage from the voltage terminal Te is impressed through a resistor 25 to a transistor 24 and the gain of the IF amplifier circuit 21 is increased.;COPYRIGHT: (C)1998,JPO