Acoustic surface wave resonator for band-blocking filter

摘要

The resonator has a substrate (22) carrying at least one interdigital transducer (25) with a pair of comb-shaped electrodes (23,24), each having a number of electrode fingers (23a,24a). The overlap zone between the interfitting electrode fingers is adjustable to obtain a transversal wave mode between the resonance point and an anti- resonance point in an impedance/frequency characteristic containing the anti- resonance point. Pref. the overlap zone has a width of between 2.8 and 3.1 times the wavelength of the acoustic surface waves.