| CPC H03H 9/02118 (2013.01) [H03F 3/189 (2013.01); H03H 9/0561 (2013.01); H03H 9/13 (2013.01); H03H 9/173 (2013.01); H03H 9/175 (2013.01); H03H 9/564 (2013.01); H03H 9/568 (2013.01); H03H 9/706 (2013.01); H03F 3/20 (2013.01); H03F 2200/294 (2013.01); H03F 2200/451 (2013.01); H04B 1/3827 (2013.01)] | 20 Claims |

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1. A bulk acoustic wave device comprising:
an air cavity;
a piezoelectric layer over the air cavity;
a first electrode positioned between the piezoelectric layer and the air cavity;
a second electrode over the piezoelectric layer; and
a multi-layer raised frame structure including a first raised frame layer and a second raised frame layer, the second raised frame layer having an acoustic impedance that is higher than an acoustic impedance of the first raised frame layer, the acoustic impedance of the first raised frame layer being lower than an acoustic impedance of the first electrode, and the second raised frame layer overlapping with the first raised frame layer over the air cavity.
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