Surface acoustic wave delay lines with small temperature coefficient

Abstract

Surface acoustic wave delay lines having a vanishing first-order temperature coefficient of delay time near room temperature have been constructed. The devices were operated near 60 MHz and had about 5 µs delay. The surface waves, generated and received using interdigital electrodes, were propagated along the twofold crystallographic axis of ST-cut quartz. The phase delay change as a function of temperature has a parabolic temperature dependence with a second-order coefficient of approximately 31.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> /° C <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .