Piezoelectric resonator utilizing electrodes larger than the polarized region for controlling the coupling coefficient thereof

Abstract

Abstract Only part of the center of a ceramic body, such as a circular disc, is subjected to a polarizing voltage. In the case of a radial mode resonator this poled area may be a circular area in the center of the major faces of the resonator. This poling is accomplished by using temporary electrodes, which may or may not become part of the final electrode structure. After the element has been thus poled, a new or added electrode is applied to the resonator. This electrode is greater in area than the area of the poling electrode, and can be placed immediately over the poling electrodes, while still making electrical contact to the adjacent area of the ceramic body, or to the poling electrode, which in turn is in contact to the ceramic. By controlling the percentage area of the final electrode that is poled it is possible to decrease the separation of the resonant and antiresonant frequencies of the piezoelectric resonator, thereby decreasing the coupling factor of the element.

Inventors

• 👤 Ralph K Helfen

Bibliographic Details