PURPOSE: To set an non-resonating point to a frequency band higher than that of a communication channel, and to improve the selectivity at a high frequency by connecting an input coupling capacitor in parallel with an input coupling inductance element.
CONSTITUTION: A TV RF signal is inputted to a TV tuner antenna input terminal 4 and inputted to an anti-resonance circuit comprising an input coupling inductance element 1 and an input coupling capacitor 6. The RF signal outputted from the anti-resonance circuit is inputted to a tuning circuit comprising a tuning inductance element 2 and a tuning varactor diode 3, mixed with a local oscillating frequency being a reception channel frequency, converted into an intermediate frequency and the resulting signal is outputted to an RE amplifier circuit 5. Thus, When the anti-resonance point is set to a frequency band higher than that of the communication channel, the high frequency selectivity is improved.
MATSUSHITA SEIJI
OZAKI TETSUYA
IWASE AKIO
