Capacitive tap weighted SAW transducers
Abstract
A new technique for SAW transducer tap weight control using thin film capacitors in a bridge-type network has been devised. In the capacitive tap weight network (CTWN), thin film capacitors made with an SiOx dielectric are fabricated on each tap in the propagation path so no additional substrate area is used. The impulse response shape is controlled by the voltage attenuation on each finger. This technique provides a large dynamic range of tap weights without phase variation and a uniform beam width which allows the cascading of two weighted transducers without the use of a multistrip coupler. The complete model used to design and implement the CTWN transducer is presented together with experimental verification using a cascaded filter.
- Publication:
-
IEEE Transactions on Sonics Ultrasonics
- Pub Date:
- September 1977
- Bibcode:
- 1977ITSU...24..293M
- Keywords:
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- Capacitors;
- Coupling Coefficients;
- Digital Transducers;
- Electrical Impedance;
- Frequency Response;
- Surface Acoustic Wave Devices;
- Capacitance;
- Electric Bridges;
- Fabrication;
- Network Analysis;
- Reactance;
- Thin Films;
- Wave Diffraction;
- Electronics and Electrical Engineering