CA2264663C — Dual loop frequency and power control

USPTO Abstract

The invention is an improved phacoemulsification probe drive circuit for supplying electrical power to an ultrasonic transducer. The drive circuit has a power control loop (1412) and a frequency control loop (1413). The power control loop (1412) has a variable gain amplifier (1416) whose output is an input to a power amplifier (1417). After the power amplifier amplifies power, power is delivered to a transformer (1436) and, thereafter, to a transducer (1439). The voltage and current applied to the primary of the transformer are sensed to generate a signal proportional to the power (real or apparent), and the result is compared against a power command originating from a foot pedal. Once compared, the result of this comparison is sent to a first controller which acts upon the information by sending a corrective signal to the variable gain amplifier.