Patent ID: 6762534
Filing Date: 2004-07-13
Classification: H03H

Abstract:
A transverse-mode-coupled resonator filter based on surface acoustic waves, in which there are disposed adjacent to one another on a piezoelectric substrate (1) a plurality of one-port resonator structures (2; 3), which comprise two strip reflectors (22 and 23; 32 and 33) and an interdigital transducer (21; 31), wherein the strip reflectors enclose a plane cavity and their reflector strips (221; 231; 321; 331) are shorted by short-circuit strips (222; 223; 232; 233; 322; 332), while the interdigital transducer is disposed in the plane cavity, the strip zones of the strip reflectors (22; 23; 32; 33) and the finger zones of the interdigital transducers (21; 31) in each one-port resonator structure (2; 3) forming, together with the short-circuit strips (222; 223; 232; 233; 322; 332) and with the collector electrodes (212; 213; 312) respectively, waveguides for surface acoustic waves, and the one-port resonator structures (2; 3) being coupled with one another by virtue of the waveguide effect, characterized in that at least one of the one-port resonator structures (2; 3) differs from the other one-port resonator structures by the ratio of the finger width to the spacing (216) of the finger centers (214; 215) and by the ratio of the width of the reflector strips (221; 231; 321; 331) to the spacing (226; 236) of the centers (224; 225 and 234; 235) of the reflector strips (221; 231; 321; 331).