GB1423684A - Surface acoustic wave logic devices - Google Patents

Abstract

1423684 Acoustic surface wave logic devices STANDARD TELEPHONES & CABLES Ltd 4 May 1973 21243/73 Heading H3U A surface acoustic wave logic device comprises a piezoelectric body, e.g. a Y-cut lithium niobate crystal, having on its propagating surface 11 areas of material 14, 18 such as wax or p.t.f.e. which absorb unwanted acoustic wave energy. In the embodiment of Fig. 1, four identical interdigitated input transducers 12, 15, 16, 17 on the surface 11 are positioned equidistantly from an output transducer 13, transducers 12, 16 and 15, 17 receiving respectively first and second r.f. input signals I/P 1 , I/P 2 . In a second embodiment (Fig. 2, not shown) two input transducers are placed at distances from an output transducer which differ by a bit length +¢# (where # is the r.f. wavelength) so that successive input signals which arrive at the input transducers in antiphase produce an output from the device. Alternatively the path lengths may differ by exactly one bit length. A third embodiment, Fig. 3, has input transducers 31, 32 and output transducers 34, 33, the signals being propagated to transducer 33 via multi-strip couplers 35, 36. In a final embodiment (Fig. 4, not shown) a single output transducer (48) extends between the two transducers of each of four input transducer pairs. To two of the input pairs are fed clock pulses and to the other two pairs are fed respective digital signals, so that the device functions as a clocked OR gate.