Integrated Surface Acoustic Wave Convolver/Amplifier.
Final technical rept. 6 May 74-6 Jun 75,
SPERRY RESEARCH CENTER SUDBURY MASS
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The work on this contract involves the development of a highly efficient surface wave convolver by means of bidirectional surface wave amplification of the counter-traveling surface waves to compensate for the attenuation they would otherwise incur. The surface wave propagates along a piezoelectric substrate YZ LiNbO3 with a semiconducting film overlay CdSe. The same interdigital electrodes which detect the convolution signal are used to apply the dc bias fields on the semiconducting film for the surface wave amplification. As a result, the surface wave convolution is considerably enhanced and the signal duration may be much longer than is possible by other techniques. The convolution efficiency of -10 dBm is 20 dB to 80 dB higher than is possible by other types of surface wave convolvers. Perhaps the most significant result of the work done under this contract was the discovery of a new mode of operation. This is a degenerate mode whose existence depends upon the bidirectional amplification of this device. It should be noted that this degenerate mode is detected by an interdigital center structure and it is even more efficient than the nondegenerate mode. The interdigital electrodes may be skewed relative to the input transducers so reflections from the electrodes no longer limit the performance of the device in any way.
- Line, Surface and Bulk Acoustic Wave Devices