Wide-bandwidth monolithic crystal filter

Abstract

A monolithic crystal filter is disclosed that provides much wider bandwidths than were obtainable by prior art crystal filters. The inventive wide-bandwidth monolithic filter includes a piezoelectric substrate, an output electrode, a plurality of input electrodes arranged in orthogonal relationship with the output electrode and common electrodes disposed opposite to the input and output electrodes. The input and output electrodes are preferably disposed on the substrate along the crystallographic axes thereof. Increased bandwidth is realized due to the increased coupling resulting from the combination of the individual couplings from each input electrode at the outputelectrode. As a result of the increased coupling provided by the inventive crystal filter, overtone mode operation is now possible at much higher frequencies which heretofore were not obtainable by prior art crystal filters due to impractically close electrode spacing requirements.

Dependencies are inferred from the claim text.