ANALYSIS OF A 3-LAYERED PIEZOELECTRIC CERAMIC TRANSFORMER FILTER

A transformer filter is fabricated with three piezoelectric ceramic di sk transducers and two sheets of thin insulator, Its equivalent circui t is derived from the Mason's model of a thickness driven piezoelectri c transducer. The electric input near its fundamental resonance freque ncy is applied to the center transducer and the output voltages across the left and right transducers are connected in parallel or in series to the resistor load. The load characteristics at resonance frequenci es under various resistor loads and the frequency characteristics near the resonance frequency under no load have been investigated. Moreove r, symbolic expressions for input impedances, voltage ratios, resonanc e frequencies, phase angles between the input and output voltages, and bandwidths have been derived. The values calculated from those symbol ic expressions are shown to agree well with the measurement values.