Wave transmission lines and networks – Coupling networks – Electromechanical filter
Patent
1980-09-26
1982-04-13
Nussbaum, Marvin L.
Wave transmission lines and networks
Coupling networks
Electromechanical filter
333155, H03H 925, H03H 964, H03H 9145
Patent
active
043250386
ABSTRACT:
Improvement in the temperature stability of a pair of resonator filters (70 and 71) disposed on an acoustic medium (39), which resonators are coupled by a first coupler means (500), is achieved by providing a second coupler means (501) for coupling between the resonator filters. The second coupler means is chosen so that acoustic interferences between waves propagating in the first and second coupling means compensates for the temperature variation in the propagation velocities of surface waves in different directions on the acoustic medium. The phase provided between second coupler means must be in near quadrature to the phase provided by the first coupler means.
In an embodiment constructed according to the present invention which utilizes parallel electromechanical (600) and folded acoustical intercavity couplers (72) to provide the necessary pair of different temperature coefficient paths, the restriction that the phases be in near quadrature provides nearly flat phase versus temperature characteristics over several tens of degrees centigrade.
REFERENCES:
patent: 4065735 (1977-12-01), Palfreeman et al.
patent: 4166228 (1979-08-01), Solie
patent: 4191934 (1980-03-01), Solie
patent: 4272742 (1981-06-01), Lewis
Coldren et al.--"Monolithic Transversely Coupled SAW Resonator Filters", 1977 Ultrasonic Symposium Proceedings, IEEE Cat. #77 CH 1264-1 SU; pp. 888-893.
Coldren et al.--"SAW Resonator Filter Overview: Design and Performance Tradeoffs", 1978 Ultrasonic Symposium Proceedings, IEEE Cat. #78 CH 1344-1 SU; pp. 422-432.
Browning et al.--"A Novel Technique for Improving the Temperature Stability of SAW/SSBW Devices", 1978 Ultrasonic Symposium Proceedings, IEEE Cat. #78 CH 1344-1 SU; pp. 474-477.
Coldren et al.--"Surface-Acoustic-Wave Resonator Filters", Proceedings of the IEEE, vol. 67, No. 1, Jan. 1979, pp. 147-158.
Rosenberg et al.--"Scattering Analysis and Design of SAW Resonator Filters", IEEE Transactions on Sonics and Ultrasoncis, vol. SU-26, No. 3, May 1979, pp. 205-230.
Coldren--"Improved Temperature Stability in SAW Resonators Using Multiple Coupling Paths", Appl. Phys. Lett. 35(9), Nov. 1, 1979, pp. 678-680.
Coldren--"The Temperature Dependence of SAW Resonator Filters Using Folded Acoustic Coupling", reprinted from Ultrasonics Symposium Proceedings, Sep. 1979, pp. 830-835.
Bell Telephone Laboratories Incorporated
Einschlag Michael B.
Nussbaum Marvin L.
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