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Optimizing CMUT geometry for high power

Yamaner, Yalçın Feysel and Olçum, Selim and Bozkurt, Ayhan and Köymen, Hayrettin and Atalar, Abdullah (2010) Optimizing CMUT geometry for high power. In: 2010 IEEE International Ultrasonics Symposium, San Diego, California (Accepted/In Press)

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Abstract

Capacitive micromachined ultrasonic transducers (CMUTs) have demonstrated various advantages over piezoelectric transducers. However, current CMUT designs produce low output pressures with high harmonic distortions. Optimizing the transducer parameters requires an iterative solution and is too time consuming using finite element (FEM) modelling tools. In this work, we present a method of designing high output pressure CMUTs with relatively low distortion. We analyze the behavior of a membrane under high voltage continuous wave operation using a nonlinear electrical circuit model. The radiation impedance of an array of CMUTs is accurately represented using an RLC circuit in the model. The maximum membrane swing without collapse is targeted in the transmit mode. Using SPICE simulation of the parametric circuit model, we design the CMUT cell with optimized parameters such as the membrane radius (a), thickness (tm), insulator thickness (ti) and gap height (tg). The model also predicts the amount of second harmonic at the output. To verify the accuracy of the results, we built a FEM model with the same CMUT parameters. The design starts by choosing ti for the given input voltage level. First, a is selected for the maximum radiation resistance of the array at the operating frequency. Second, tm is found for the resonance at the input frequency. Third, tg is chosen for the maximum membrane swing. Under this condition, a frequency shift in the resonant frequency occurs. Second and third steps are repeated until convergence. This method results in a CMUT array with a high output power and with low distortion.

Item Type:Papers in Conference Proceedings
Subjects:T Technology > TK Electrical engineering. Electronics Nuclear engineering
ID Code:15139
Deposited By:Ayhan Bozkurt
Deposited On:12 Nov 2010 10:34
Last Modified:12 Nov 2010 10:34

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