Low drift relative phase sensor employing surface acoustic waves

摘要

Pairs of input transducers are formed on the surface of a piezoelectric crystalline body. The input transducers in each pair produce adjacent parallel surface acoustic waves of opposite polarity and specific phase difference which are sensed by a corresponding output transducer. The input transducers of each pair are offset from one another by amounts related to the wavelength of the surface acoustic wave so that a maximum cancellation of the voltages induced in the output transducers by the acoustic waves can be used to indicate the relative delay or phase difference of signals applied to the input terminals and to do so in a manner which is insensitive to temperature variation from one point to another in the piezoelectric crystal.