Patent ID: 7365619
Filing Date: 2008-04-29
Classification: H03H

Abstract:
1. A BAW filter having a ladder structure, comprising a signal input and a signal output related to a common ground, at least one series resonator or one parallel resonator of the BAW filter being configured as a BAW apparatus, the BAW apparatus comprising: a first BAW resonator and a second BAW resonator connected antiparallel, wherein the first BAW resonator and the second BAW resonator comprises a common piezo layer, and wherein a first area of the common piezo layer is associated to the first BAW resonator and a second area of the common piezo layer is associated to the second BAW resonator, a polarization of the common piezo layer in the first area and a polarization of the common piezo layer in the second area are unidirectional and the first BAW resonator and the second BAW resonator are electrically operated in inverted phase.