Resonant frequency calculation of square diaphragms: A comparison

A comparative study has been carried out to establish the relative accuracy of 5 models that are widely used to calculate the resonant frequency of square diaphragms used to fabricate capacitive micromachined ultrasonic transducers (CMUT). Both laminated and single layer diaphragms were considered for a wide range of diaphragm sidelengths. The models predicted values were compared with 3-D finite element analysis (FEA) results carried out using IntelliSuite™. It appears that though the models can predict the resonant frequency with reasonable accuracy for relatively large diaphragms as necessary for low frequency applications, all the models deviate significantly from FEA values for smaller diaphragms that are required for high frequency applications. Consequently, it is necessary to improve the accuracy of the existing closed-form models to determine the resonant frequency of the laminated square diaphragms used to design CMUTs for high frequency applications.