engleski

Estimating Ultrasound Transmitter Parameters Using 1-D Equivalent Circuit Models

Calculation scheme for estimating ultrasound piezoelectric transducer parameters in form of RLC, KLM and Mason equivalent circuit has been implemented in MATLAB and used to characterize transducer before its physical construction. Input parameters for equivalent circuits have been found using impedance data measurements of piezoceramic samples as free resonators. Equivalent circuits enable flexible manipulation input impedance of transducer system and gives estimated transfer function of the system in frequency domain near thickness extensional mode. Transfer function can be given as a ratio of radiated pressure, surface velocity or force (on active surface) and applied voltage in frequency domain. Several configurations of transducers have been made from PZT-5A ceramic of different thickness and diameter for studying influence of ultrasound field on human tissue. Transducers have been constructed as systems with active piezoelectric element, n&middot ; ; ; ; λ /4 matching element section in front of active element face (made from perspex), air-backing on back face, and cable. Estimated input impedance of ultrasound system radiating in water depending on frequency using KLM and Mason equivalent circuit model were compared with measurement results in frequency range near thickness extensional mode of constructed ultrasound transducers configuration. Transfer function in form of ratio of (pressure on surface with input voltage is estimated with theoretical models. Measured and theoretical conductance is used for calculating available bandwidth of constructed transducers.

equivalent circuit; input impedance; transfer function

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