Motorola Corporation

Brian C Walker

David G Clifford

Robert J Munn

A ceramic filter (120) with at least one transmission zero is disclosed. The filter (120) has a filter body comprising a block of dielectric material and having top (110), bottom (112), and side surfaces, and having metallized through-holes extending from the top to the bottom surfaces defining resonators. The surfaces are substantially covered with a conductive material defining a metallized layer. The top surface (110) is uncoated. The filter (120) can also include input-output pads ( 104, 106). The bottom surface (112) has a channel (108) defining a magnetic coupling between the resonators. The channel configuration and placement can vary depending on the desired frequency response.

Ceramic filter with channeled features to control magnetic coupling

A bandwidth agile, dielectrically loaded resonator filter is disclosed in which conductive strips (320, 322), plated on the top surface (302) of the filter and disposed between resonators (310, 312, 314), are selectively switched to ground in order to affect a change in the bandwidth without appreciably changing the center frequency of the filter response. PIN diode switching networks (316, 318), including a means for biasing the diode, are used to effectively ground the strips between the nearly quarter-wavelength transmission line resonators contained within the block (300) of the filter, thereby capturing a portion of the capacitive coupling (402, 404) which occurs mostly beneath the surface of the filter between adjacent resonators.

Growing community of inventors

Albuquerque, NM, United States of America

Brian C Walker