Study on the equivalent circuit of a microfabricated ultrasonic micro-knife and PZT driving power

In this paper an equivalent circuit model is established for an ultrasonic micro-knife, which is fabricated by using MEMS Technology and driven by the piezoelectric PZT-4 plates. In this model, the overall electrical characteristics of micro-knife is equivalent to a RC network, the mechanical properties reflected in a form of series resonance branch, and the parameter value of the components in this resonance branch will changed when external load conditions varied. Based on these analysis, we developed a piezoelectric device driving power system using high-voltage operational amplifier, current power amplify circuit, adjustable compensation circuit and dual independent power sources. The tested results demonstrate that the developed power supply has advantages of high frequency, low-power consume, high-power output, small size, good dynamic response and stability in driving capacitive loads, and can meet well with needs of the micro-knife.