GB1345731A - Surface wave transducer - Google Patents

Abstract

1345731 Acoustic surface wave devices INTERNATIONAL BUSINESS MACHINES CORP 22 June 1971 [30 Sept 1970] 29323/71 Heading H3U [Also in Division G4] An acoustic surface wave device comprises a piezo substrate 11, Fig. 3, supporting pairs 44, 38; 42, 36 of electrodes which, in response to a data input pulse provide a pair of positive going pulses (16), Fig. 2 (not shown) separated by a region of zero signal level, the negative going portion between the pulses, which would have been produced by the pair 38, 42 having been deflected, by auxiliary electrodes 48, 46, so that it is not received at receiving transducer 62. The auxiliary electrodes may be conductively separate from the other electrodes. A second transducer 56, 54; 52, 50; 60, 58 produces a negative going pulse and a positive going pulse, separated by a zero level region, (18) Fig. 2 (not shown). Receiving transducers 78, 62 of similar construction to the second transducer, and transducer 32 receive the respective waveforms (18, 16), and produce respective three pulses output waveforms, (22, 20) of relative pulse magnitudes (-1, +2,-1), (+1, +2, +1) with respect to the acoustic input pulses which, when added, give a single output pulse (24), of relative magnitude (+4). In Fig. 6, the receiving transducers 102 are so phased and spaced that, for a particular three digit input sequence, supplied to transducers 100, the output is maximized. The device can thus be used for binary sequence pattern recognition. The gain-bandwidth product in transducers for data processing can be increased using the above techniques. The load 94 may be a resistor.