Ultra‐wideband SAW resonator composed of grooved Cu electrodes and its application to tunable filters

Abstract

A cognitive radio system, which is being investigated in order to use limited frequency resources effectively, requires a tunable filter with a wide variable frequency range. A wideband resonator is required to realize a tunable filter. It was reported that a resonator composed of a Cu electrode/15° YX-LiNbO 3 had a large bandwidth of 12%. We attempted to fabricate a one-port resonator composed of a grooved Cu electrode/4° YX-LiNbO 3 . This resonator was applied to a tunable filter, and a tunable filter having a tunable range of 6.8% in the center frequency was experimentally realized using a bandpass-type filter circuit, and one having a tunable range of 9 to 12% was theoretically realized using a ladder-type filter circuit.