An advanced equivalent circuit for a piezoelectric micromachined ultrasonic transducer and its lumped parameter measurement

In this work, we developed an advanced equivalent circuit model for a piezoelectric micromachined ultrasonic transducer. The mechanical lumped parameters and the radiation impedance were obtained by considering the double-layer plate of a unimorph circular plate. Through the equivalent circuit model, the effect of a piezoelectric layer on the mechanical lumped parameters was considered. The model-produced admittance curves were compared with the measured admittance curves of the pMUT unit to verify the equivalent circuit model. A pMUT unit with a circular silicon radiating plate (radius 600 μm, thickness 15 μm) was used for measurements.