Abstract: The disclosure relates to a novel device for performing signal convolution functions such as auto and cross correlation through the use of combined acoustic surface wave and semiconductor devices. A detector or pickup unit comprising a plurality of interdigital fingers coupled to associate semiconductor diodes is disposed on the surface of an acoustic substrate in the path of surface waves propagated along the surface of the substrate. The diodes are operatively connected to a summing bus from which an output signal indicative of some characteristics of the surface waves may be obtained.

Abstract: The disclosure relates to an acoustic surface wave device and method for long signal delays and bulk wave discrimination through the folding of a surface wave propagation path. A surface wave device is formed on the surface of an acoustic substrate and a surface wave, acoustic discontinuity is formed in the propagation path of surface waves propagated along the surface of the substrate. The acoustic discontinuity defines a reflecting surface for acoustic surface waves thereby deflecting incident surface waves along a reflecting path differing from the propagation path. Substantially all of the bulk waves propagated along the propagation path continue along this path and can be absorbed or otherwise dissipated. As a result, a substantially pure surface wave mode signal can be detected along the reflecting path. The surface waves may be reflected in this manner, i.e., by folding the path of the surface waves, a number of times as required to obtain a desired delay.

Abstract: A thin film piezoelectric transducer generates bulk mode ultrasonic elastic waves which propagate into a transmission medium, such as silicon. The wave is reflected back towards the first transducer by a reflecting surface. A second transducer is located adjacent to the first transducer and receives the acoustic wave from the reflected surface. The path length of the ultrasonic wave from the first transducer to the second transducer is long enough to enable the bulk wave to be in the Fraunhofer field. An acoustic absorbing material, such as indium, may be placed on the reflecting surface and on the surface containing the two transducers in selective areas to reduce undesired reflections. The structure is suitable for use in the microwave region wherein the insertion loss may be relatively constant over a given frequency band.