Ultra wide band resonator composed of grooved Cu-electrode on LiNbO<inf>3</inf> and its application to tunable filter

Abstract

A leaky surface acoustic wave (LSAW) on 0-15°YX-LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> has a large electro-mechanical coupling factor, but it has a leaky component. The LSAW changes to Love wave without its leaky component, by using a high density metal electrode with a low velocity such as Au and Cu on that substrate. It was reported that a resonator composed of a Cu-electrode/15°YX-LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> had wide bandwidth of 12%. This time, in order to obtain a resonator with a wider bandwidth, authors attempted to fabricate one-port resonators composed of a grooved Cu-electrode/4°YX-LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . As the result, this resonator had a wider bandwidth of 17% of 1.3 times and higher resonant and anti-resonant frequencies of 1.3 times than the resonator composed of a conventional type of same thick Cu-electrode on 4°YX-LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> for reference. Authors proposed to apply this resonator to a tunable filter. As the result, the tunable filter having tunable range of 7% in center frequency was realized.