Electro-acoustic resonator
AssigneeNXP B.V.
InventorsRobert Milsom, Hans-Peter Lobl
Life of this patent
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Abstract
An electro-acoustic resonator (1, 8, 17) of the membrane or FBAR type (1) or the solidly-mounted or SBAR type (8), with electrodes comprising a single conducting layer or multiple conducting layers, i.e. sandwich construction (17) with an optimum coupling factor kr and thus an improved filter bandwidth. The optimum coupling factor kr is achieved by the arrangement that the top electrode (6, 15, 25) is thinner than the bottom electrode (4, 13, 23). The coupling factor is independent of the resonator's layout defined by the mask.
Claims12
Electro-acoustic resonator (1, 8, 17) with a layer structure comprising a piezoelectric layer (5, 14, 24) and a top (6, 15, 25) and a bottom (4, 13, 23) electrode layer, with the thickness (T1, T2, . . . T6) of the two electrode layers being unequal, characterised in that the top electrode layer (T1, T3, T5) is thinner than the bottom (T2, T4, T6) electrode layer.
Dependencies are inferred from the claim text.