Patent ID: 6522220
Filing Date: 2003-02-18
Classification: H01P

Abstract:
A frequency variable filter comprising:a plurality of serial resonance sections each formed by a resonator and a resonance capacitor electrically connected in series; an input terminal and an output terminal connected to respective ones of said plurality of serial resonance sections; a coupling element electrically connecting the input terminal and the output terminal; a plurality of serial circuits each composed of a frequency shifting capacitor and a switching element, each of the serial circuits being electrically connected in parallel with a respective one of the resonators of the plurality of serial resonance sections; wherein switching the switching elements on/off varies both the frequency of an attenuation pole and an attenuation bandwidth of said filter; junctions defined respectively between the frequency shifting capacitors and the switching elements in each of the serial circuits; and a coupling capacitor electrically connected between said junctions.