A system is provided for applying ultrasound power to treat human tissue comprising a transducer driven by an oscillating signal from a power amplifier. The transducer and power amplifier have a power-conversion-efficiency characteristic which is a function of the frequency of the oscillating signal...http://www.google.es/patents/US4966131?utm_source=gb-gplus-sharePatente US4966131 - Ultrasound power generating system with sampled-data frequency control
Ultrasound power generating system with sampled-data frequency control
