Bulk acoustic wave filter e.g. for band-pass HF filters, has layered structure with capacitance connected in parallel or in series with resonator

摘要

A resonator functioning with bulk acoustic waves (BAW) has a layer sequence containing a lower layer region comprising a first electrode, an upper layer region comprising a second electrode, a piezoelectric layer arranged between the first and second electrodes, and a capacitance connected in parallel or in series with the resonator. Independent claims are included for (A) a filter with ladder-type arrangement and (B) a duplexer containing at least one filter and (C) an electric circuit containing a resonator stack.