BAW FILTER STRUCTURE HAVING INTERNAL ELECTROSTATIC SHIELD

摘要

PROBLEM TO BE SOLVED: To provide a bulk elastic wave (BAW) filter structure having internal electrostatic shield bringing the filtering performance, improved compared with an unshielded BAW filter structure, by reducing impact of parasitic capacitance.;SOLUTION: A shielded BAW filter structure includes a substrate 12, multiple transducers 16 on the substrate, and a flat surface electrostatic shield 66 between the substrate and upper electrodes 20 of the multiple transducers. Each of the multiple transducers forms a part of a BAW resonator 10, and exists in a filter including the parasitic capacitance. The flat surface electrostatic shield is bound to a ground node so as to reduce parasitic capacitance, and shuts off an electric field associated with the parasitic capacitance of the filter.;SELECTED DRAWING: Figure 8A;COPYRIGHT: (C)2019,JPO&INPIT