Method and apparatus for driving a piezoelectric transducer with stored charge recovery

A method for driving a piezo device comprising:

• multiplying an input signal V(s) by an oscillator signal f(s) to provide a pulse width modulated pulse train VPWM control signal;
• controlling a switching amplifier in accordance with the pulse width modulated pulse train VPWM control signal to provide a filtered alternating current (AC) driver signal and a returned charge direct current (DC) signal;
• applying the filtered AC driver signal to the piezo device;
• and
• returning stored charge of the piezo device to a battery with the DC signal.

A piezo driver system comprising:

• a driver including
• a switching amplifier coupling a power port to a plurality of driver ports;
• a switch controller coupled to the switching amplifier;
• an oscillator creating an oscillator signal f(s);
• and
• a modulator having a first input coupled to an input signal V(s), a second input coupled the oscillator signal f(s), and an output coupled to the switch controller, wherein the modulator multiplies the input signal V(s) by the oscillator signal f(s) to provide a pulse width modulated pulse train VPWM signal;
• a battery coupled to the power port;
• and
• a plurality of piezo devices coupled to the plurality of driver ports;
• wherein the driver provides a plurality of filtered driver signals to the plurality of piezo devices and returns stored charge of the plurality of piezo devices to the battery.