| 摘要 |
The invention relates to a filter device equipped with at least one bulk acoustic wave resonator, which comprises a resonator unit and a reflection element (2) comprising several layers (6, 7, 8). The layers (6, 7, 8) each comprise a mixture of at least two materials. Within each layer (6, 7, 8), the composition of the mixture varies continuously and periodically relative to the layer thickness.
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