Abstract
Acoustic wave filter devices are disclosed. In an embodiment, the device includes an acoustic wave resonator and a reflecting layer located below the acoustic wave resonator. The wave resonator includes an input electrode including a first electrode and a counter electrode, a piezoelectric layer sandwiched between the first electrode and the counter electrode, and an output electrode. The piezoelectric layer has a first region covered by the first or the output electrode, and a second region not covered by any of the first and the output electrode. The first region has a second order acoustic thickness-shear resonance (TS2) mode dispersion curve with a first minimum frequency, and the second region has a TS2 mode dispersion curve with a second minimum frequency. The reflecting layer's thickness is such that a difference between the first minimum frequency and the second minimum frequency is less than 2% of a filter center frequency.
Patent family as of 27.1.2022
US11223341 BB 20220111 US20190660480 20191022
US2021119600 AA 20210422 US20190660480 20191022
WO21078916 A2 20210429 WO2020EP79840 20201022
WO21078916 A3 20210722 WO2020EP79840 20201022
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| Original language | English |
|---|---|
| Patent number | US2021119600 |
| IPC | H03H 9/ 54 A I |
| Priority date | 22/10/19 |
| Publication status | Published - 22 Apr 2021 |
| MoE publication type | H1 Granted patent |