Electronique Serge Dassault

Jean-Louis Foure

Benoit Noel

A surface acoustic electric wave device of the type comprising, over a large face of a planar piezo-electric substrate, a first row of parallel conductive fingers having an individual geometry chosen and distributed according to a chosen distribution arrangement along this row, a second row of parallel conductive fingers having an individual geometry chosen and distributed according to a chosen distribution arrangement along this row, the second row being interspaced from the first so as to allow a propagation of surface acoustic waves between the fingers of the first row and those of the second, which imparts to the device spectral and/or temporal characteristics defined by the acoustic propagation and the frequency selectivity due to the geometry of the fingers. The geometries of the fingers are chosen, in correspondence as from one row to the other, in order to obtain an acoustic coupling with a wide frequency bandwidth, and one of the two distribution arrangements or sequences for the attachment of the fingers is modified substantially periodically.

Acoustic electric surface wave device

The invention concerns electric/acoustic input transducers and acoustic/electric output transducers, in particular for a surface wave device, of the type comprising on a large face of a planar piezoelectric substrate: (i) two conductive input zones or output zones separated by a substrate band over which there extend respective parallel fingers which are interlaced according to a pattern chosen to form a row of fingers along this band, the general direction of the band being inclined to the direction of the fingers; and (ii) electric input means for applying high frequency signals between the zones so as to form sources of surface acoustic waves on the substrate or output means for extracting the signals detected by the device. At least one of the two conductive input or output zones is subdivided into electrically separated sub-zones, while the electric input means comprise a distributor capable of separately energizing the conductive input zones and while the electric output means comprise a coupler capable of combining the electric signals coming from said output sub-zones.

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Verrieres le Buisson, France

Jean-Louis Foure