JPS55105426A - Elastic surface wave device - Google Patents

Abstract

PURPOSE:To enhance the frequency/temperature characteristics for the elastic surface wave device using the crystal, by selecting the crystal axis with the electrode film provided on the propagation line. CONSTITUTION:The electrode film thickness, the electrode finger width and the distance between electrode fingers of the transducer are referred to as h0, a and b respectively. And then the crystal plate is selected based on the relation between the equation using wavelength lambda and X=a.h0/(a+b).lambda and the cut-out angle theta of the crystal from the Z axis as theta=(-18707.5X<2>+21.429X+129.5) degrees. Thus no spurious is caused on such crystal plate to the surface wave of propagation of the X axis. Furthermore, the temperature property can also be increased by using the Au electrode. Also the electrode is provided on the propagation line of the surface wave, and thus the displacement can be concentrated onto the surface owing to the effect of the mass load of the electrode. Thus the loss can be reduced. Here, the Au electrode can feature the power of influence of about 40 times as much as that of the Al electrode, and as a result an elastic surface wave device can be obtained with the long-time delay characteristics and with less amount of loss.