Publications Details

Equivalent-Circuit Model for the TSM Reasonator with a Viscoeleastic Film Near Film Resonance

Bandey, H.L.; Martin, S.J.; Cernosek, R.W.

A new equivalent-circuit model for the thickness shear mode resonator with a surface viscoelastic layer will be described. This model is valid only in the vicinity of a film resonance but is a reasonable approximation away from resonance. A simple resonant parallel circuit containing a resistor, a capacitor, and an inductor represents the electrical impedance of the film. These elements describe the film's viscous power dissipation, elastic energy storage, and kinetic energy storage, respectively. Resonator response comparisons between this lumped- element model and the general transmission-line model show good agreement over a range of film phase conditions and not just near film resonance. Under certain conditions, it will be shown that two peaks in the admittance magnitude are observed for operation at film resonance.