High-frequency filter device, filter device combined to a transmit-receive antenna, and wireless apparatus using the same

摘要

A high-frequency filter device including at least one filter to be connected to a high-frequency stage of a wireless apparatus, in which the filter includes a voltage-controlled variable frequency resonance element which comprises a resonance element and a voltage-controlled variable impedance element electrically connected to the resonance element. The high-frequency filter device includes a control section for controlling a voltage applied to the variable impedance element, and a signal monitoring section for outputting a control signal, with which the voltage is controlled, to the control section based on frequency data as to an oscillating frequency of a local oscillator of the wireless apparatus, and the signal monitoring section controls a band frequency of the at least one filter based on the frequency data in such a manner that the band frequency is adaptively changed. <IMAGE>