Thomson-csf

Marc Solal

Jean Desbois

Pierre Dufilie

Jean-Michel Hode

Jean-Francois Gelly

Emmanuelle Briot

Sylvain Ballandras

Pascal Ventura

A filter with surface acoustic wave resonators using an equivalent electrical bridge structure to obtain a good form relationship, i.e., a relationship between the filter rejection band and its pass band. Bridge arms advantageously include the paralleling of several resonators, thereby not requiring additional electrical elements as in the background art which provides for the use of series-connected resonators. Particular implantation methods for preparing equivalent structures to paralleling several resonators are also disclosed.

Filter with surface acoustic wave resonators

A low-loss surface acoustic wave filter on a quartz substrate with optimized cutting. A range of cutting angles and directions of propagation of the waves on the quartz substrate are defined, making it possible to obtain high coefficients of reflection of the electrodes used in the filter. The range of cutting angles and directions of propagation of the waves are decisive factors for the making of the filter.

Low-loss surface acoustic wave filter on quartz substrate with optimized cut

Surface acoustic wave filter utilizing the coupling of three acoustic

Surface acoustic wave transducer driven in differential mode

The disclosure relates to differential input/output surface acoustic wave devices with proximity coupling. The disclosed device comprises a whole number N of acoustic channels, where N is at least equal to two. The acoustic channels are coupled together by proximity. A first acoustic channel comprises at least one transducer separated into several parts electrically connected in parallel with one another to form a first differential port (E+) and a second differential port (E-). The polarities of the different parts of the transducer are chosen so that the first differential port (E+) and the second differential port (E-) are electrically symmetrical. Application in particular to surface acoustic wave filters for portable telephones.

Differential input/output surface acoustic wave device with proximity

The distributed acoustic reflection transducer has a reflection function which includes at least one reversal of sign, that is to say it possesses at least one reflector and, in general, a combination of reflectors, the center of which is at a distance of k.lambda./2+.lambda./4 from the center of the other reflectors, .lambda. being the wavelength corresponding to the central operating frequency of the transducer. The applications will be for the production of surface-wave filters in radio communication systems.

Surface-wave distributed acoustic reflection transducer and filter

Surface wave filter filtering delay transfer function

Antenna, in particular for a sonar, allowing to form directional channels by feeding the transducers by a reduced number of sources by means of an interpolation network that permits to maintain to a low level the image lobes in spite of this reduction of the number of sources.

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Antibes, France

Marc Solal