Tuner apparatus

DETAILED DESCRIPTION Briefly described, the inventive tuner apparatus comprises a voltage controlled variable reactance device provided in common to a plurality of receiving bands and being supplied with a tuning voltage from a single tuning voltage generating means.
The tuner apparatus further comprises means for restricting the upper and lower limits of the tuning voltage being applied.
The inventive tuner apparatus is adapted to establish a relation in which the tuning voltage for tuning to the maximum receivable frequency of one receiving band among the plurality of receiving bands is equal to or higher than the tuning voltage for tuning to the maximum receivable frequency of the remaining receiving bands and the tuning voltage for tuning to the minimum receivable frequency of the remaining one receiving band among the plurality of receiving bands is equal to or lower than the tuning voltage for turning to the minimum receivable frequency of the remaining receiving band.
Therefore, according to the present invention, it is not necessary to provide a tuning voltage restricting means for each of the receiving bands in restricting a variation range of the tuning frequency already restricted or being restricted in the future.
Accordingly, the tuning frequency of the inventive tuner apparatus can be assuredly adapted to the frequency range as restricted with a simple circuit configuration.
In a preferred embodiment of the present invention the tuning voltage generating means may be of a voltage synthesizer type.
The tuning voltage generating means of such voltage synthesizer type comprises a switching device being rendered conductive responsive to a pulse signal and a smoothing circuit for smoothing the output of the switching device.
In such embodiment, impedance means is interposed in a current path of the switching device for allowing a predetermined residual voltage to be applied to the smoothing circuit even when the switching device is rendered conductive.
According to the above described preferred embodiment, the lower limit of the tuning voltage can be restricted with a very simple structure