Determining equivalent circuit parameters for low figure of merit transducers

Abstract

A new analytical technique for deriving transducer equivalent circuit parameters from complex electrical admittance data is presented. The new method handles low figure of merit transducers (those having weak coupling and/or low Qm), but does not require phasor subtraction or similar geometrical manipulations of the admittance loop. Four parameters of the unloaded, single degree-of-freedom equivalent circuit are extracted from a simple analysis of the capacitance curve, B(ω)/ω, and one additional parameter is obtained from the dissipation curve, G(ω)/B(ω). This technique simplifies the evaluation of developmental transducers, particularly those using marginal or weakly polarized materials.