Monolithic programmable signal processor using PI-FET taps

Claim 1

A monolithic programmable signal processor comprising: a substrate, having a first conductivity type, selected from the group of semiconductors comprising silicon (Si) and indium phosphide (InP); a first piezoelectric layer formed on a first portion of said substrate; at least one transducer for generating surface acoustic waves propagating along the surface of said first piezoelectric layer along a predetermined path; a set of parallel source electrodes having a second conductivity type formed in said substrate along said predetermined path in the region underlying said first piezoelectric layer, said parallel source electrodes being disposed perpendicular to said predetermined path of said surface acoustic waves and said second cuductivity type being opposite said first conductivity type; a set of parallel drain electrodes having said second conductivity type interdigitally formed in said substrate between said first set of parallel source electrodes, each of said interdigitally formed parallel source and drain electrodes being separated from each other by a predetermined interelectrode space; and gate means formed on the surface of said piezoelectric layer for controlling the conductivity between said gate and source electrodes, said gate means covering at least the portion of said piezoelectric layer which overlays each of said interelectrode spaces.