Surface-acoustic-wave devices with low sensitivity to mechanical and thermoelastic stresses.

Abstract

Surface-acoustic-wave (SAW) devices with a low sensitivity to both temperature and stresses effects are presented and experimentally tested. Devices are built on SAW quartz cuts with zero first-order temperature coefficient and zero sensitivity to planar isotropic stresses. In comparison with similar devices built on conventional (ST, X) cuts, two kinds of experiments are reported. First, devices built on circular quartz plates are submitted to in-plane diametrical compressions. The force-frequency effect is measured and results are compared to theoretical predictions either by analytical models or using finite element analysis. In a second experiment, the same devices are submitted to in-plane thermoelastic stresses in a dynamical thermal regime. It is shown that the sensitivity of the new cuts to dynamical thermal effects is one order of magnitude lower than the conventional (ST, X) cut, an attractive potentiality for fast-warm-up high-stability SAW oscillators in severe environmental conditions.