Abstract: The present invention relates to radioelectronics and can find application in developing signal frequency discriminators. According to the invention, the filter comprises a piezoelectric-crystal plate 1 made of La--Ga silicate, two pairs of overlap exciting electrodes 2, 3 and 4, 5, and leads 6. There were selected experimentally in the proposed filter such a ratio between the length of the electrodes along the axis of acoustical coupling, the area of the electrodes, and the wafer thickness that makes it possible to extend the filter frequency range towards higher frequencies. The proposed filter construction provides for a higher temperature stability of the filter average frequency in a wide range of above-zero temperatures, and a reduced level of side passbands.

Abstract: A surface acoustic wave device capable of exhibiting high temperature stability and being downsized. The device includes a wafer constructed of a trigonal lanthanum/gallium silicate crystal cut out at predetermined cut angles (.alpha., .beta.). Application of a predetermined voltage signal to the wafer permits a surface acoustic wave to be excited in the wafer and propagate in the wafer. Supposing that the crystal has three crystal axes including an X-axis (electric axis), a Y-axis (mechanical axis) and a Z-axis (optical axis), the wafer is cut out so that a normal line (n) on a surface of the wafer has the cut angle .alpha. defined to be 20.degree..ltoreq..alpha..ltoreq.40.degree. with respect to the Y-axis in a counterclockwise direction from the Y-axis in a Y-Z plane and a propagation direction (S) of the surface acoustic wave has the cut angle .beta. defined to be 35.degree..ltoreq..beta..ltoreq.70.degree.