Acoustic wave filter with acoustic velocity adjustment structure

A wireless communication device comprising:

• a filter including a multi-mode surface acoustic wave filter having a first interdigital transducer electrode on a piezoelectric layer, an acoustic reflector on the piezoelectric layer, a second interdigital transducer electrode on the piezoelectric layer, and an acoustic velocity adjustment structure positioned over at least a gap between the first interdigital transducer electrode and the second interdigital transducer electrode, the second interdigital transducer electrode longitudinally coupled to the first interdigital transducer electrode and positioned between the first interdigital transducer electrode and the acoustic reflector, the acoustic velocity adjustment structure arranged to increase an acoustic wave propagation velocity in a first region that includes the gap relative to a second region over at least a portion of the first interdigital transducer electrode;
• an antenna operatively coupled to the filter;
• a radio frequency amplifier operatively coupled to the multi-mode surface acoustic wave filter and configured to amplify a radio frequency signal;
• and
• a transceiver in communication with the radio frequency amplifier.