A system for performing an ocular surgical procedure is provided. The system includes a multiple frequency signal source, a configurable tuned output filter connected to the multiple frequency signal source, and a multiple frequency ultrasonic handpiece. The multiple frequency signal source operates at a first frequency and is configured to drive the configurable filter and the multiple frequency ultrasonic handpiece at the first frequency. The multiple frequency signal source operates at a second frequency and is configured to drive the configurable filter and the multiple frequency ultrasonic handpiece at the second frequency, and the design addresses third harmonic frequency issues for the multiple frequency ultrasonic handpiece. Switchable passive components, such as inductors, resistors, and/or capacitors may be employed in the configurable tuned output circuit, or alternately multiple similar circuits may be employed. Alternately, a multi-tap transformer may be provided.