Three-transducer saw device including one or two apodized transducers having minimum-phase and maximum-phase impulse responses

摘要

In a three-transducer surface acoustic wave device, an apodized electrode member (15) is interposed between two interdigi­tal electrode members (16, 17), each having first and second ends and comprising interdigital electrodes between the first and the second ends either with a uniform density distribution or with a density distribution varied according to a prescribed rule of selective withdrawal of the interdigital electrodes. The apodized electrode member has first and second extremities and is given substantially minimum-phase and maximum-phase impulse responses for surface acoustic waves which are propagated from the apodized electrode member through one and the other of the extremities. Alternatively, an interdigital electrode member of the type described is interposed between two apodized electrode members capable of either transmitting or receiving surface acoustic waves to and from the interdigital electrode member with substantially minimum-phase and maximum-phase impulse responses.