Automatic Calibration and Assessment of Thickness Mode Piezoelectric Transducers

Abstract

automatic measurement system which may be implemented on a microprocessor. The technique is based on the transient analysis of the time domain voltage step response of a thickness mode device. Such a transient technique is amenable to automation and if configured p roperly can provide accurate, repeatable and reliable results over a wide range of transducer configurations. This work describes the theoretical development and hardware instrumentation of a system required for the automated measurement of thickness mode piezoelectric transducer constants. The method is based on a transient analysis of the transducer voltaqe s tep response in the t ime domain. Important d evice parameters such as static capacitance, coupling coefficient, piezoelectric charge constant, mechanical resonant frequency, bulk velocity, specific acoustic impedance, absolute permittivity and mechanical stiffness in the thickness direction may be obtained from a single measurement and results are a ccurate to within * 5%.