Patent ID: 7123309

Claim:
A television tuner provided with a mixer for subjecting one of entered digital television signals and analog television signals to frequency conversion into an intermediate frequency band and an intermediate frequency tuning circuit so configured as to enable a tuning frequency to be switched within the intermediate frequency band and arranged at a stage immediately following the mixer, wherein the intermediate frequency tuning circuit is tuned to a first frequency substantially at a center of the intermediate frequency band when the digital television signals are entered into the mixer and tuned to a second frequency higher than the first frequency when the analog television signals are entered into the mixer, wherein Q of the intermediate frequency tuning circuit is lowered when the digital television signals are entered into the mixer, and wherein the Q is raised and the tuning frequency is tuned substantially to a video intermediate frequency in the intermediate frequency band when the analog television signals are entered into the mixer, the intermediate frequency tuning circuit has a parallel tuning circuit to be substantially tuned to the video intermediate frequency, a series circuit including a switch diode and capacitance elements, and a resistor connected in parallel to the capacitance elements, the series circuit is connected to the parallel tuning circuit in parallel, and the switch diode is turned on when the digital television signals are entered into the one of the mixer and the switch diode is turned off when the analog television signals are entered into the mixer.