Transducer resonance

A transducer (including any attached resonant components -- i.e., the stack) is resonant when the applied voltage and current are in phase (i.e., zero phase angle).

For any specified mode (e.g., the axial mode) in a piezoelectric transducer, there are two adjacent resonances that depend on the interaction of the ceramics with the mechanical components of the transducer. These resonances are called short circuit resonance and open circuit resonance. Short circuit resonance falls somewhat below open circuit resonance. The frequency difference between these two resonances will increase as the total ceramic capacitance increases and will decrease as the relative energy storage of the stack increases.

The designer may choose to operate at or near either series or parallel resonance, depending on the resonance characteristics and power supply characteristics that he desires.