Wave transmission lines and networks – Coupling networks – Electromechanical filter
Patent
1995-09-15
1998-11-03
Pascal, Robert J.
Wave transmission lines and networks
Coupling networks
Electromechanical filter
333195, 333196, 310313R, 310313B, H03H 9145, H03H 964
Patent
active
058314920
ABSTRACT:
Selected transducer geometries including unbalanced split electrode and three electrode per wavelength structures are employed for use in wide band tapered SAW devices. Combining geometries useful in narrow bandwidth SAW filters for canceling reflected waves leading to triple transit interference, and electrode tapering useful in wide bandwidth SAW filters for permitting transduction of a wide range of surface acoustic wavelengths has the unexpected result of significantly reducing insertion loss and improving triple transit suppression over wider bandwidths than can be achieved with SPUDT designs on non-tapered devices. The interdigitized electrode fingers of opposing bus bars in the transducer have a tapered alignment wherein a period of electrode finger portions along an acoustic wave propagation axis decreases along a transducer dimension. In one embodiment, the transducer has spacing between the electrode fingers which provides two pairs of unbalanced split electrodes within a spacing length equal to its respective acoustic wavelength. The positions and widths of the fingers are such that SPUDT transduction and reflection conditions are satisfied. In an alternate embodiment, the transducer has three electrodes per acoustic wavelength wherein the electrode widths and gaps between electrodes vary to satisfy the SPUDT transduction and reflection conditions. The performance of each transducer is further enhanced with subtransducers for providing series-block weighting. The three electrode per wavelength finger geometry further includes line-width weighting for providing a fine weighting control to complement the inherently coarse weighting control of the series-block weighted transducer.
REFERENCES:
patent: 3870975 (1975-03-01), Vasile
patent: 4114116 (1978-09-01), Reeder
patent: 4162465 (1979-07-01), Hunsinger et al.
patent: 4203082 (1980-05-01), Tsukamoto et al.
patent: 4316161 (1982-02-01), Moore et al.
patent: 4321696 (1982-03-01), Kanda
patent: 4331840 (1982-05-01), Murphy et al.
patent: 4348904 (1982-09-01), Bautista, Jr.
patent: 4449107 (1984-05-01), Asai et al.
patent: 4480209 (1984-10-01), Okamoto et al.
patent: 4486724 (1984-12-01), Schofield
patent: 4516049 (1985-05-01), Mikoshiba et al.
patent: 4600905 (1986-07-01), Fredricksen
patent: 4602228 (1986-07-01), Yamada
patent: 4625184 (1986-11-01), Niitsuma et al.
patent: 4635008 (1987-01-01), Solie
patent: 4672592 (1987-06-01), Skinner
patent: 4746882 (1988-05-01), Solie
patent: 4749971 (1988-06-01), Solie
patent: 4767198 (1988-08-01), Solie et al.
patent: 4908542 (1990-03-01), Solie
patent: 4973875 (1990-11-01), Yatsuda
patent: 5075652 (1991-12-01), Sugai
patent: 5289073 (1994-02-01), Mariani
"Weighting Interdigital Surface Wave Transducers By Selective Withdrawal of Electrodes," C. S. Hartmann, Texas Instruments Inc., 1973 Ultrasonics Symposium Proceedings, pp. 423-426.
"Design Of Low-Loss Saw Filters Employing Distributed Acoustic Reflection Transducers," T. Komada, et al., Toshiba R/D Center, 1986 Ultrasonics Symposium Proceedings, pp. 59-64.
"Capacitive Tap Weighted SAW Transducers," D.C. Malocha/B.J. Hunsinger, IEEE Transactions on Sonics and Ultrasonics, vol. SU-24, No. 5, Sep. 1977.
"Matching of Single-Phase Undirectional SAW Tranducers and a Demonstration Using a Low-Loss EWC/SPUDT Filter," B.P. Abbott/C.S. Hartmann/D.C. Malocha, University of Central Florida, 1990 Ultrasonics Symposium Proceedings, pp. 49-54.
"Wide Band Linear Phase SAW Filters Apodized Slanted Finger Transducers," P.M. Naraine/C.K. Campbell, Ontario, Canada, 1983 Ultrasonics Symposium Proceedings, pp. 113-116.
Improved Design of Single-Phase Undirectional Tranducers for Low-Loss Saw Filters, C.B. Saw and C.K. Campbell, Microwave Acoustics Laboratory, Dept. of Electrical and Computer Eng., McMaster Univ., Hamilton, Ont., Canada L8S 4L7-IEEE 1987 Ultrasonics Symposium Proceedings, pp. 169-172, Oct. 14-16, 1987.
Surface Acoustic Wave Device Supriyo Datta, Prentice Hall, Englewood Cliffs, NJ 07632. .COPYRGT.1986.
Pascal Robert J.
Sawtek Inc.
Summons Barbara
LandOfFree
Weighted tapered spudt saw device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Weighted tapered spudt saw device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Weighted tapered spudt saw device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-693896