US Patent 7538473 Drive circuits and methods for ultrasonic piezoelectric actuators

A drive circuit for and method of driving a piezoelectric actuator utilizes an impedance coupled to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency. A first circuit is provided that drives the actuator at the resonant frequency and a second circuit is further provided that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to be energized at a first duty cycle and a second mode that causes the actuator to be energized at a second duty cycle.