Combined use of Finite Element and Equivalent Circuit Modeling for System-Level Simulation of Integrated Capacitive Micromachined Ultrasonic Transducers (CMUT)

Abstract

This paper proposes the combined use of Finite Element Modeling (FEM) and Equivalent Circuit Modeling (ECM) to describe the nonlinear electromechanical and acoustic behavior of a CMUT in an integrated circuit simulation environment. CMUT ECM lumped parameters are computed by FEM simulations. The proposed method is implemented in LTSpice, and validated by comparing ECM and FEM static, small-signal harmonic, and large-signal transient simulation results. The model was then applied to the performance assessment of the CMUT coupled to a realistic integrated transceiver configuration by computing TX efficiency and noise figure. The proposed approach allows accurate large-signal analysis of CMUTs interfaced to ultrasound front-end circuits by considering non-ideal characteristics of the system, such as the pulser nonlinearities.