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US 8,941,451 B2Granted
Broadband SAW filter
AssigneeEpcos AG
InventorsMohamed Elhakiki, Heiko Hartmann, Jacques Antoine Damy
Life of this patent
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Abstract
A new type of very broad bandwidth filters with small insertion loss and high return loss are given. The new filter uses a substrate that can propagate a PSAW and fan shaped transducers of low metallisation height, high metallisation ratio, low reflectivity and high coupling coefficient.
Claims16
A filter working with acoustic waves of the pseudo surface acoustic wave (PSAW) type comprising:
- a piezoelectric substrate chosen to propagate a PSAW;
- and
- a first transducer arranged on the substrate and comprising a plurality of cells with a respective electrode finger combination, the cells being arranged after one another in a longitudinal direction, at least some of the cells being SPUDT cells;
- wherein the transducer is a fan type transducer, where a width of each transducer finger and a spacing between the fingers of a respective pair of adjacent transducer fingers are enhancing in a transversal direction;
- and
- wherein the fan type cells are adapted to provide a relative bandwidth of the transducer of at least 8%.
3 more elements
Dependencies are inferred from the claim text.