Surface acoustic wave (SAW) resonator e.g. for narrow-band bandpass filters and oscillators

摘要

The surface wave resonator has a piezo-electric substrate (1). Two single gate resonator structures (2,3) each having two strip reflectors (22,24,32, 34) defining a hollow chamber (21,31) and connected by short-circuit strips. An interdigitated transducer (IDT) (23,33) is arranged in each hollow chamber (21,31). In each resonator structure (2,3) the strips of the strip reflectors or the teeth of the interdigital convertor together with the short circuit strips or with collector electrodes, form waveguides for acoustic surface waves. Both resonator structures (2,3) are arranged in the direction of the convertor teeth and reflector strips at a distance such that both resonator structures are coupled together. The resonator structures are defined differently in the length of the hollow chamber and/or in the spacing between adjacent teeth and/or reflector strips. The convertors of each structure are each made up of two partial convertors arranged one behind another perpendicular to the convertor teeth. The spaces between the teeth of the convertors may or may not be different.