An accurate equivalent circuit for the clamped circular multiple-electrode PMUT with residual stress

In this work, an equivelent circuit model is analytically derived for a multiple electrode unimorph piezoelectric micromachined transducer (pMUT) including the influence of residual film stresses and electrical diaphragm tensioning, for the first time. The derived model is confirmed with finite element (FEM) simulation of a circular plate lead zirconate titanate based pMUT operating in air. With further use of the analytical model and FEM, a novel pMUT design consisting of two electrodes excited by opposite polarities is proposed and shown to improve transmission power efficiency and reduce second order harmonics.