Ultrathin multimode quartz crystal filter element

摘要

PCT No. PCT/JP90/01528 Sec. 371 Date Jan. 24, 1992 Sec. 102(e) Date Jan. 24, 1992 PCT Filed Nov. 22, 1990 PCT Pub. No. WO91/19352 PCT Pub. Date Dec. 12, 1991.Since split electrodes are disposed along the x-axis of an AT cut quartz crystal plate on its ultrathin vibratory portion formed integrally with a thick frame-like marginal portion surrounding it, desired acoustic coupling can be obtained although the split electrodes are disposed closely to such an extent as not to cause shorting between them. It is therefore possible to obtain, with a satisfactory yield, filter elements which have center frequencies in the range greater than about ten megahertz and sufficiently wide passbands.