Ultrasound power generating system with sampled-data frequency control

摘要

A hand held applicator for applying ultrasound power to treat human tissue, includes a transducer (1) having excitation electrodes. A power amplifier (13) responds to an oscillating signal from a variable frequency oscillator (23) to supply electrical power to the transducer (1) via a connection to the excitation electrodes. The transducer (1) and the power amplifier (13) have a power-conversion-­efficiency characteristic that is a function of the frequency of the oscillating signal and the acoustic load on the transducer (1). The frequency of the oscillating signal is controlled by a sampler (5) having a timer for defining alternating sample and hold timing intervals and means for producing a frequency-control signal having a magnitude that varies during each sample interval and that remains essentially constant during each hold interval. The means for producing the frequency-control signal includes a peak-detector operative during each sample interval for setting the magnitude of the frequency-­control signal so that throughout the ensuing hold interval the transducer and the power amplifier operate with essentially peak-power-conversion efficiency.