ASA 127th Meeting M.I.T. 1994 June 6-10

2pEA8. Producing a distortion-free output from a PMN/PT transducer using large driving voltages.

S. E. Forsythe

J. C. Piquette

Naval Res. Lab., Underwater Sound Reference Detachment, P. O. Box 568337, Orlando, FL 32856

PMN/PT (lead magnesium niobate/lead titanate) is an electrostrictive ceramic that exhibits high strains when an unpoled sample is subjected to a high voltage. The strain as a function of voltage is an almost perfect square law, s=kV[sup 2], over a large range of voltages, neglecting higher-order effects such as hysteresis and saturation. This response suggests that a transducer made of PMN/PT should be driven using an ac signal superimposed upon a large bias voltage. The bias voltage is needed to achieve a large effective strain/volt in response to the ac signal. If the ac signal amplitude is greater than a few percent of the bias voltage, significant distortion appears in the output due to the nonlinear response. To achieve the full potential response of this material, it is desirable to shape the driving signal such that the ac voltage swings over nearly twice the bias voltage while faithfully reproducing the desired signal at the output. Techniques for accomplishing this, even when the desired signal is complex or transient, by using models and their inverses are discussed and experimental results are presented. [Work supported by Office of Naval Research.]