Abstract: A method of manufacturing a monolithic crystal filter, and particularly a filter having a high midband frequency (e.g., 20 MHz or above) and a wide resonator coupling (e.g., 4 KHz or above), involves the plating of additional electrode material onto a pair of base-plated split electrodes on one side of a crystal wafer to establish a desired coupling between resonators of the filter. Additional electrode material then is plated onto a base-plated solid electrode on the opposite side of the crystal wafer to establish a desired midband frequency of the filter. When the electrodes are plated in this sequence, the resonator coupling decreases substantially during the additional plating of the split electrodes, but remains essentially constant, within tolerance limits, during the plating of the solid electrode, whereby further adjustment of the coupling is not necessary.

Abstract: An improved monolithic piezoelectric bandpass filter unit, suitable for single side band applications, having a pair of finite poles introduced into one of its stopbands.