Acoustoelectric SAW phase shifter

A new acoustoelectric phase shifter is proposed which produces a direct phase shift of a SAW on piezoelectric substrate. Computations of the attenuation and phase lag versus resistivity due to a silicon wafer air-gap coupled to yz-LiNbO3 are presented. The use of the variation of the resistivity of the silicon to control the phase of a SAW was demonstrated using the photogeneration of carriers and the field-effect control of the surface resistivity. A 180° shift was obtained with a +30-V transverse voltage pulse.