schaltungsanordnung for a tuner to switch two frequenzbaender.

摘要

The invention relates to a circuit arrangement for a tuner, particularly a television tuner, for a change over switching between two frequency bands with the aid of a switching diode, said frequency bands, particularly the VHF band and the hyperband, being filtered out by means of bandpass filters (1,7). The bandpass filters have at their inputs and outputs capacitance diodes for the purpose of tuning. The filtered signals are applied to a common tunable circuit (15) on the secondary side of the bandpass filters. The bandpass filter for the hyperband is constructed and dimensioned such that the signal is switched through by means of a switching diode (83) arranged at the low end of the bandpass filter (1). When this diode (83) is conducting a smaller output reactance, whereas in the case of a blocking switching diode (83), this bandpass filter (1) cuts off the signal and has a larger output reactance. Furthermore, the bandpass filter (7) for the VHF band is constructed and dimensioned such that it filters out the desired frequency range in the case of a larger output reactance of the first bandpass filter (1) and is detuned in the case of a smaller output reactance of the first bandpass filter (1).