| 摘要 |
PROBLEM TO BE SOLVED: To prevent production of an undesired wave by making a surface acoustic wave stipulated by a nearly circular-arc shaped comb-line electrode obliquely incident on an output electrode, mismatching the wave as an elastic energy and propagating only the surface acoustic wave in the basic mode. SOLUTION: A surface acoustic wave convolver element is configured by forming nearly circular-arc shaped interdigital input electrodes 12, 13, an output electrode 14 and a bonding pad 15 onto a Y-cut Z propagation lithium niobate piezoelectric substrate 11. Anglesγ1,γ2 between a bisecting line 22a-22b of a center angle of a circular arc of an electrode finger of the electrodes 12, 13 stimulating and focusing the surface acoustic wave and an axial line 21a-21b of the electrode 14 guiding the wave are selected to be 0-14 deg.. Furthermore, a width of the electrode 14 is selected to be nearly four times of a wavelength of the surface acoustic wave and the electrode 14 provides an output by utilizing the nonlinear effect of the substrate 11. A convolution signal of the surface acoustic wave is extracted by the pad 15. Thus, only the surface acoustic wave of the 0-th mode is propagated and outputted to prevent production of an undesired wave.
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