Apparatus for high efficiency, high safety ultrasound power delivery with digital efficiency indicator and one clock cycle shutdown

Abstract

The invention in general relates to Medical Instruments for bone fracture healing, ultrasonic surgery, tissue ablation and cutting and drilling, dry powder inhalers and more particularly to a method to monitor load condition and overall efficiency, safety and reliability of ultrasonic energy delivery using a Class E power Amplifier. Three parameters: frequency (f), duty cycle (D) and Power Amplifier supply voltage (Vdd) are continuously adjusted in order to maintain optimal and suboptimal Class E operation. The load for the power driver can be a single element or a stack. For every frequency and duty cycle of operation the MOSFET drain voltage is compared to a known value which is proportional to Power Amplifier supply voltage Vdd. During the MOSFET OFF part of operation a timer is started when drain voltage falls below a known threshold value. The timer is stopped by the MOSFET leading edge gate clock. A measure of the distance from optimal operation is implemented in the form of a counter value N thus allowing a continuous load monitoring. A one Class E Amplifier clock cycle reaction to fast load change is thus possible and therefore a robust efficient operation, with increased safety and reliability of Ultrasonic power delivery.