Tunability of the band structure of a piezoelectric phononic crystal using electrical negative capacitance

This work deals with the control of the propagation of ultrasonic waves in a piezoelectric phononic crystal (PC) by mean of electrical negative capacitance charges. In a first step, a theoretical and experimental study of a unit block of the PC constituted by a piezoelectric plate connected to a negative capacitance is performed in the MHz frequency range. An electrical circuit based on the current feedback operational amplifiers is proposed in order to achieve experimentally the negative capacitance. In a second step, the experimental transmission of waves through a PC constituted by a stack of piezoelectric layers connected to negative capacitance is studied and compared to the theoretical band structure of the piezoelectric PC.