Resonant Inc.
TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATORS WITH MULTIPLE PIEZOELECTRIC MEMBRANE THICKNESSES ON THE SAME CHIP

Abstract:

A filter device with multiple piezoelectric plate thicknesses if fabricated on a single chip by bonding a piezoelectric plate to a surface of a substrate having swimming pool shunt and series cavities. Non-selected areas of the plate have a thickness for shunt resonators and form shunt membranes of the plate that span the swimming pool shunt cavities. Selected areas of a back surface of the plate have a thickness for series resonators and form series membranes of the plate that span the swimming pool series cavities but not the swimming pool shunt cavities. The thickness for series resonators is thinner than that for shunt resonators. Shunt interdigital transducers (IDTs) are on a front surface of the plate over the swimming pool shunt cavities; and series IDTs are on a front surface of the plate over the swimming pool series cavities.