Patent ID: 9667225
Date: 2017-05-30
CPC Classifications: H03H

Claim:
1. A surface acoustic wave filter comprising: a piezoelectric substrate; a longitudinally coupled resonator first filter section provided on the piezoelectric substrate; and a longitudinally coupled resonator second filter section that is electrically connected to the first filter section in parallel or in series on at least one of an input signal side and an output signal side and that is provided on the piezoelectric substrate next to the first filter section in a surface acoustic wave propagation direction; wherein the first filter section includes a first interdigital transducer group including a plurality of interdigital transducers (IDT) arranged in the surface acoustic wave propagation direction and a pair of first reflectors disposed on each side of the first interdigital transducer group in the surface acoustic wave propagation direction; the second filter section includes a second interdigital transducer group including a plurality of interdigital transducers arranged in the surface acoustic wave propagation direction and a pair of second reflectors disposed on each side of the second interdigital transducer group in the surface acoustic wave propagation direction; the first reflector and the second reflector disposed between the first interdigital transducer group and the second interdigital transducer group are defined by an integrated shared reflector; a number of electrode fingers in reflecting units in the integrated shared reflector is an odd number of no less than nine; the pair of first reflectors includes the shared reflector and a non-shared reflector that is not integrated with the second reflector; and an interval between the shared reflector and an interdigital transducer of the plurality of interdigital transducers in the first interdigital transducer group that is adjacent to the shared reflector, is different from an interval between the non-shared reflector and an interdigital transducer of the plurality of interdigital transducers in the first interdigital transducer group that is adjacent to the non-shared reflector.