Wave transmission lines and networks – Coupling networks – Delay lines including elastic surface wave propagation means
Reexamination Certificate
1999-12-17
2001-11-20
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Delay lines including elastic surface wave propagation means
C333S148000, C333S196000, C333S201000, C310S026000
Reexamination Certificate
active
06320479
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to magnetostrictive surface acoustic wave (SAW) devices and, in particular, to magnetostrictive SAW devices provided with improved transducers for enhanced performance.
BACKGROUND OF THE INVENTION
SAW devices are important components in RF circuits, especially in wireless communication devices. SAW devices are particularly important as delay elements. They provide low-velocity, non-dispersive propagation with low attenuation up to microwave frequencies and a propagation path which is accessible at a substrate surface.
While conventional SAW devices are not readily integrated into silicon microelectronic circuits, applicants' above-referenced U.S. application Ser. No. 09/137,431 describes magnetostrictive SAW devices which can be fabricated on silicon substrates. These devices can be integrated with microelectronic circuits useful in wireless communications.
In essence, a magnetostrictive SAW device comprises a substrate, a film of an appropriate magnetostrictive material disposed on the substrate, an input transducer for generating horizontally polarized shear waves along the film and an output transducer for receiving the shear waves. The substrate can comprise silicon and include one or more microelectronic circuit elements interconnected with the magnetostrictive SAW device. The transducers are typically serpentine (meander-type) electrodes.
The present invention provides devices of this type with improved transducer structures for enhanced performance.
SUMMARY OF THE INVENTION
In accordance with the invention, magnetostrictive saw devices are provided with improved transducer structures for enhanced performance. In one improved device, the transducers are in the form of gratings with interconnected ends for reduced resistance and inductance. In another embodiment, the transducers are shaped to provide apodization. In yet a third embodiment, transducer performance is enhanced by patterning composite structures.
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Alers Glenn B.
Ellis Kenneth Alexander
Klemmer Timothy J.
van Dover Robert Bruce
Agere Systems Optoelectronics Guardian Corp.
Lowenstein & Sandler PC
Pascal Robert
Summons Barbara
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