US 11,606,072 B2 · Filter circuit

Abstract

The present invention relates to a filter circuit (100) comprising a first and a second bulk acoustic wave resonator (2, 3), the first resonator (2) having a first piezoelectric layer (4) structured such that the first resonator (2) has a lower resonant frequency than the second resonator (3), wherein the first piezoelectric layer (4) is structured by recesses (14) passing through the first piezoelectric layer (4), the first resonator (2) and the second resonator (3) as series resonators (102, 105) connected in series with a signal path of the filter circuit (100) or wherein the first resonator (2) and the second resonator (3) as parallel resonators (103, 106) are connected to the signal path of the filter circuit (100) in such a way that in each case one electrode of the resonators is connected to the signal path.

Claims20

Dependent claims

A filter circuit, comprising

a first and a second bulk acoustic wave (BAW) resonator, the first BAW resonator having a first piezoelectric layer structured such that the first BAW resonator has a lower resonant frequency than the second BAW resonator, wherein the first piezoelectric layer has a plurality of recesses formed in the first piezoelectric layer, wherein at least one of the plurality of recesses extends through an entirety of a thickness of the first piezoelectric layer and at least one of the recesses does not extend through the entirety of the thickness of the first piezoelectric layer, and wherein:
the first BAW resonator and the second BAW resonator are series resonators that are connected in series with a signal path of the filter circuit, or
the first BAW resonator and the second BAW resonator are parallel resonators that are connected to the signal path of the filter circuit such that one electrode of each of the BAW resonators is connected to the signal path.

Dependencies are inferred from the claim text.

Filter circuit

Life of this patent

Filter circuit

Life of this patent

Abstract

Claims20