ULTRA THIN QUARTZ CRYSTAL FILTER ELEMENT OF MULTIPLE MODE.

摘要

An ultra thin quartz crystal filter element of multiple mode including a quartz crystal elementary plate of AT-cut constituted in a body by an ultra thin vibrating part and a thick annular part surrounding the vibrating part. Split electrodes are arranged on the vibrating part along the X-axis of the elementary plate, being close to each other to an extent that the electrodes are not short-circuited. Desired acoustical coupling can be obtained in spite of the closely arranged electrodes. Therefore, a filter element having a center frequency of tens to hundreds MHz and having a sufficient pass band can be obtained with good yield.