Analytical design of circular CMUT cells in immersion

Analytical design of Capacitive Micromachined Ultrasound Transducers gives insight on the effect of geometrical parameters and material properties of CMUT on its performance. I. Wygant et al. presented at IEEE IUS 2009 equations for design of circular CMUT cell based on desired resonance frequency, quality factor and pull-in voltage. In this paper, we extend their work by capturing the impact of spring softening on resonance frequency. We propose a simple method to calculate CMUT 3-dB bandwidth in immersion utilizing equivalent circuit. Finally, A design flow is presented based on optimizing CMUT performance in immersion. Design of 50 MHz CMUT is illustrated using analytical approach. FEM results supports the validity of proposed design equations and design methodology in shown cases.