Research on Basic Characteristics of Piezoelectric System Shunted with Negative Capacitance

Basic characteristics of piezoelectric system shunted with negative capacitance are studied in this paper. After established general frequency domain equations of piezoelectric system shunted with negative capacitance, the expressions of natural frequency, dynamic stiffness and generalized electro-mechanical coupling factor are obtained. For the case there is only a negative capacitance in the shunting circuit, natural frequency of piezoelectric system will be changed with the ratios of open-circuited inherent piezoelectric capacitance and negative capacitance; what´s more, it can move to any frequency when the proper ratio is given. The dynamic stiffness dependent on the above mentioned ratio will become soft or rigid at specific frequency regions. For piezoelectric system shunted with negative capacitance in series or parallel, the generalized electro-mechanical coupling factor could be enhanced to nearly 1 when the ratios change in different regions. These basic characteristics are important in some applications of piezoelectric system, e.g. sensors and actuators.