BAW FILTER STRUCTURE HAVING INTERNAL STATIC ELECTRICITY SHIELDING FUNCTION

摘要

Embodiments of the present invention relate to a bulk acoustic wave (BAW) filter structure having an internal electrostatic shielding. The shielded BAW filter structure in the exemplary embodiments of the present invention includes: a substrate; a plurality of transducers on the substrate; and a planar electrostatic shielding unit between the upper electrode of the plurality of transducers and the substrate. Each of the transducers forms a part of a BAW resonator and resides in a filter combined between an input node and an output node. The planar electrostatic shielding unit is connected to a ground node and blocks an electric field related to the parasitic capacitance of a filter in order to reduce parasitic capacitance. Therefore, the filter includes parasitic capacitance capable of affecting filtering performance such as filter rejection degradation. The planar electrostatic shielding unit is combined with a ground node and blocks an electric field related to the parasitic capacitance of the filter in order to reduce the parasitic capacitance. Therefore, the shielded BAW filter structure reduces the effect of the parasitic capacitance providing filtering performance which is increased compared to the non-shielded BAW filter structure.;COPYRIGHT KIPO 2019