US 12,255,611 B2
Thin-film saw device with multilayer waveguide
Michael Smirnow, Munich (DE); and Matthias Knapp, Munich (DE)
Assigned to RF360 Singapore Pte. Ltd., Singapore (SG)
Appl. No. 17/441,197
Filed by RF360 Singapore Pte. Ltd., Republic Plaza (SG)
PCT Filed Mar. 30, 2020, PCT No. PCT/EP2020/058983
§ 371(c)(1), (2) Date Sep. 20, 2021,
PCT Pub. No. WO2020/201222, PCT Pub. Date Oct. 8, 2020.
Claims priority of application No. 10 2019 109 031.8 (DE), filed on Apr. 5, 2019.
Prior Publication US 2022/0173713 A1, Jun. 2, 2022
Int. Cl. H03H 9/02 (2006.01)
CPC H03H 9/02574 (2013.01) [H03H 9/02535 (2013.01); H03H 9/02834 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A SAW device comprising:
a carrier substrate,
a piezoelectric thin-film on the carrier substrate,
an interdigital electrode structure on the piezoelectric thin-film,
a layer stack of waveguide layers, the layer stack being arranged between the carrier substrate and the piezoelectric thin-film, wherein
the layer stack comprises a first waveguide layer and a second waveguide layer,
a sound velocity in the first waveguide layer is at least 1.5 times as great as a sound velocity in the second waveguide layer, and
a TCF compensating layer having a positive temperature coefficient of frequency arranged between the layer stack and the carrier substrate.