Parameter extraction methods for piezoelectric-based transducer design

An accurate electric circuit model is a requirement to achieve correct design, as the transducer needs to be connected to an oscillator or a charge amplifier. This paper makes a comparison of two different methods for parameter extraction, namely: admittance and vector fitting. The first method makes use of the maximum points of the impedance and admittance curves of the crystal. The second method does the rational polynomial fitting of the impedance curve. This is the first time vector fitting methodology is applied to crystal parameter extraction. The impedance curves were measured with a precision impedance meter, controlled by a computer over GPIB (IEEE-488).