Linear saw signal processor

Abstract

Signals extracted from the taps of a surface acoustic wave (SAW) device, as a consequence of a single wave propogating therein or as a consequence of interaction between a pair of waves propagating therein, are processed by linearly-controlled nonlinear product mixing and/or amplifying devices, to provide output signals in a serial chain of chips of RF, the magnitude of chips being dependent upon unique, selected bias applied to corresponding ones of the devices. The devices may be diodes operating in a bias range to provide impedence greater than the capacitive reactance impedance of the taps to which they are attached, thereby providing a linear RF voltage to DC bias current characteristic, while at the same time providing a nonlinear DC voltage to DC current characteristic for RF product mixing (where used); or the devices may comprise transistors, either field effect or bipolar, with similar suitable bias considerations when linearly-controlled product mixing is desired. Applications, with or without output frequency isolation from input frequencies, include time division multiplexing of DC signals (such as transducer output signals), and transversal filtering, of the type useful in correlation or other wave or coded signal analysis.