Principles of Strip-Coupled SAW Memory Correlators

Abstract

Abstmcr-The correlators considered are fabricated on substrates of GaAs and do not employ overlay films. Radio frequency (RF) input to a correlator is accomplished through the use of conventional interdigital transducers. The output port of the memory correlator is composed of an interdigital structure, each tap of which connects to a GaAs Schottky diode at the edge of the acoustic beam. Resistive channel effects in side-fed Schottky diodes are analyzed and discussed. Detailed operating characteristics for the storage process and its linearity are presented. Similarly detailed analyses of the varactor properties and the correlation process are examined. First principles prediction of the correlator efficiency is shown to be within a few tenths of a dB of the experimental values. Physical bounds on the RF power requirements from the drive circuitry of the memory correlator are presented as a function of the handwidth-time (BT) product for this architecture.