Design theory of piezoelectric ceramic transformer as an asymmetric filter

Abstract

AbstractThe piezoelectric ceramic transformers as a source for a high voltage is used in a high‐energy density state due to its small size so that the energy loss causes increased heat generation and reduction of efficiency. Therefore, it must be treated not only for the voltage step up but as a power transmission system. In the conventional design method for the piezoelectric ceramic transformer, only the voltage ratio was considered important.In this paper, the piezoelectric ceramic transformer is considered as an asymmetric filter with a different capacitance ratio and different termination resistances of the input and output parts. The transmission frequency and the termination condition for a low propagation loss and a high‐voltage ratio were found. As a figure of merit of the piezoelectric ceramic transformer, the voltage ratio x relative bandwidth was proposed. By taking into account this value and the transmission attenuation, an optimum circuit condition of the piezoelectric ceramic transformer was obtained.