DISPERSION TYPE SURFACE ACOUSTIC WAVE DELAY LINE

摘要

PURPOSE:To suppress the increase in a null point level of a conversion output by selecting the ratio of an electrode finger pair number of comb-teeth-shaped electrodes constituting one transducer to an electrode finger pair number of other transducer as >=10. CONSTITUTION:An input transducer 2 and an output transducer 3 comprising comb-teeth-shaped electrodes are formed along the propagation direction of a surface acoustic wave shown in the arrow are formed on the piezoelectric substrate 1. Electrode fingers having a width of nearly lambda0/8 are arranged at an interval of nearly lambda0/8 to constitute the input transducer 2 whose comb-teeth- shaped electrodes having an equal pitch consist of electrode fingers weighted as shown in broken lines by the cross width. The output transducer 3 is constituted by comb-teeth-shaped electrodes comprising a couple of normal strip electrode fingers. In selecting the ratio of the electrode finger pair number of the comb- teeth-shaped electrodes constituting the input transducer 2 to the electrode finger pair number of the output transducer 3 as >=10, a delay line with a low null point level in a conversion output is obtained.