Study on generation mechanisms of third-oder nonlinearity in SAW devices

In this paper, generation mechanisms of third-order nonlinearity in surface acoustic wave (SAW) devices are discussed. For this discussion, a simulation technique, in which all conceivable generation mechanisms are taken into account, is proposed. In the simulation procedure, nonlinear stress and electric flux at each electrode finger are estimated by using results of linear analysis and eight nonlinear terms. Then, their contributions are embedded as the voltage and current sources, respectively, in an equivalent circuit model, and nonlinear signals appearing at an external port are estimated. It is shown that each nonlinear coefficient can be determined from a series of experiment carried out in various driving frequencies. This is because influence of each nonlinear term to the nonlinear output changes markedly with the driving conditions.