General Electric Company

A Gordon Staples

Gerald E Roberts

Samuel Toliver

A monolithic coupled-dual resonator crystal filter is produced for operation with wide bandwidths (especially at high center frequencies) by providing an ultra-small gap between juxtaposed resonator electrodes. A gap width of substantially less than 0.006 inch is obtained by laser-machine trimming the gap. An initial single electrode may thus be divided into a pair of such juxtaposed resonator electrodes. Further metallic plate-back is provided on the electrodes for center-frequency control. Although this typically may decrease the coupling bandwidth somewhat, an increased thickness of metallic plate-back material on the ground electrode, opposite the ultra-thin gap area on the active side of the crystal wafer, provides precisely controlled extra wide bandwidth.

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Evergreen, VA, United States of America

A Gordon Staples