Abstract: A surface acoustic wave device includes a surface acoustic wave substrate having two IDT electrodes including wiring electrode portions made of aluminum disposed thereon. First, second and third metal films are laminated on each of the wiring electrode portions. The first metal film has superior bondability to aluminum, and the third metal film has superior bondability to bumps. In addition, the second metal film has an ability to suppress the diffusion of the metal defining the first metal film.

Abstract: A surface acoustic wave device includes a piezoelectric substrate, at least one IDT disposed on the piezoelectric substrate, and an input end and an output end connected to the IDT. At least one of the input end and the output end includes a pair of balanced signal terminals, and a delay line or a reactance component connected to one of the pair of balanced signal terminals.

Abstract: A three-electrode longitudinally-coupled-type SAW resonator filter has an improved level of selectivity by effectively suppressing unwanted large spurious responses generated in a range higher than the pass band. A first ID electrode, a second ID electrode and a third ID electrode are disposed on a piezoelectric substrate. Reflectors are provided on one side of each of the second and third ID electrodes, respectively. A center distance L.sub.1 between the most adjacent electrode fingers of the respective first and second ID electrodes is differentiated from the center distance L.sub.2 between the most adjacent electrode fingers of the respective first and third ID electrodes. Further, the first ID electrode is weighted to more effectively suppress undesired spurious responses.

Abstract: A longitudinal coupling type SAW resonator filter achieves improved selectivity without increasing the insertion loss and is constructed so as to be more easily mass-produced. The longitudinal coupling type SAW resonator filter has a piezoelectric substrate and first, second and third sets of interdigital electrodes each including a pair of comb electrodes disposed on the piezoelectric substrate. A pair of reflectors are located on the opposite sides in the surface wave propagation direction of the area in which the first to third sets of interdigital electrodes are disposed. The distance between the centers of adjacent electrode fingers of the first and second sets of interdigital electrode and the distance between the centers of adjacent electrode fingers of the first and third sets of interdigital electrode are set to different values.

Abstract: A SAW resonator filter apparatus includes attenuation characteristics which are steep in a frequency region from a pass band to a higher-frequency stop band without experiencing an increase in insertion losses and enlargement of the apparatus. First, second and third SAW resonator filters are disposed on a piezoelectric substrate and are connected in a cascade arrangement to each other. The first and third SAW resonator filters have interdigital electrodes formed of solid electrode fingers, while the second SAW resonator filter disposed between the first and third filters has interdigital electrodes formed of split electrode fingers. With this construction, the steep attenuation characteristics of the response in a higher frequency range appearing in the frequency characteristics of the second SAW resonator filter can be combined with the attenuation characteristics from the pass band to a higher-frequency stop band of the first and third SAW resonator filters.