Kapasitif mikro-işlenmiş ultrasonik çevirgeçlerin kazanç-band genişliği çarpımlarının optimizasyonu

ABSTRACT OPTIMIZATION OF THE GAIN-BANDWIDTH PRODUCT OF CAPACITIVE MICROMACHINED ULTRASONIC TRANSDUCERS Selim Olcum M.S. in Electrical and Electronics Engineering Supervisor: Prof. Dr. Abdullah Atalar January, 2005 Capacitive micromachined ultrasonic transducers (cMUT) have large bandwidths, but they typically have low conversion efficiencies. This thesis defines a performance measure in the form of a gain-bandwidth product, and investigates the conditions in which this performance measure is maximized. A Mason model corrected with finite element simulations is utilized for the purpose of optimizing parameters. There are different performance measures for transducers operating in transmit, receive or pulse-echo modes. Basic parameters of the transducer are optimized for those operating modes. Optimized values for a cMUT with silicon nitride membrane and immersed in water are given. The effect of including an electrical matching network is considered. In particular, the effect of a shunt inductor in the gain-bandwidth product is investigated. Design tools are introduced, which are used to determine optimal dimensions of cMUTs with the specified frequency or gain response. Keywords: Capacitive Micromachined Ultrasonic Transducers (cMUT), Transducer Gain, Bandwidth. m