ABSTRACT
The results of a theoretical and experimental investigation of the SAW propagation characteristics in an optimal region of langasite defined by the Euler angles phi from -15 degrees to +10 degrees, theta from 120 degrees to 165 degrees, and psi from 20 degrees to 45 degrees are presented. Based on temperature coefficients of the elastic constants derived from experimental data, some optimal orientations of langasite characterized by high electromechanical coupling factor (k2), zero power flow angle (PFA) and low or zero temperature coefficient of frequency (TCF) were found. The SAW velocity in the region of interest is highly anisotropic; this results in a significant amount of diffraction, which must be taken into account in the search for orientations useful for SAW devices. An orientation having simultaneously zero PFA, zero TCF, negligible diffraction, and relatively high piezoelectric coupling has been found and verified experimentally. The experimental results are in excellent agreement with the calculated SAW characteristics. The frequency response of a SAW device fabricated on the optimal cut of langasite is presented and demonstrates that high performance SAW filters can be realized on this optimal cut of langasite.
ABSTRACT
The emerging technology of acoustic charge transport (ACT), which has enabled the implementation of powerful signal processors capable of handling high-speed RF and microwave signals in their natural analog domain, is reviewed. The development of ACT technology has led to the implementation of fully programmable analog signal processors capable of performing over 45 billion multiply-and-accumulate operations per second. These processors are finding application as adaptive filters and equalizers in a variety of commercial and military systems. The operation and performance capabilities of the ACT device are described, and seven applications now under development are discussed.
