Acoustic wave device with velocity adjustment layer

A surface acoustic wave device comprising:

• a piezoelectric layer;
• a first reflector over the piezoelectric layer;
• a second reflector over the piezoelectric layer;
• an interdigital transducer electrode structure over the piezoelectric layer and positioned between the first reflector and the second reflector, the interdigital transducer electrode structure having a first side closer to the first reflector and a second side closer to the second reflector;
• and
• a low speed layer positioned in a slow region over the first reflector such that an acoustic wave propagation velocity in the slow region is slower than an acoustic wave propagation velocity in a region between the first side and the second side.

A wireless communication device comprising:

• a filter including a surface acoustic wave device having a piezoelectric layer, a first reflector over the piezoelectric layer, a second reflector over the piezoelectric layer, an interdigital transducer electrode structure having a first side closer to the first reflector and a second side closer to the second reflector over the piezoelectric layer and positioned between the first reflector and the second reflector, and a high speed layer positioned over at least a portion between the first side and the first reflector such that an acoustic wave propagation velocity in a fast region overlapping the high speed layer is greater than an acoustic wave propagation velocity in a region between the first side and the second side;
• an antenna operatively coupled to the filter;
• a radio frequency amplifier operatively coupled to the filter and configured to amplify a radio frequency signal;
• and
• a transceiver in communication with the radio frequency amplifier.