Motorola Corporation

Cts Corporation

Truc G Hoang

Reddy R Vangala

Reddy Vangala

Thomas G McVeety

Antonije Djordjevic

David G Clifford

Frederick L Sassin

Douglas A Morris

Darren V Weninger

Daniel H Balinski

The present invention is a preferred monoblock ceramic bandpass duplexer filter. The preferred filter has at least three I/O pads. One of the pads is coupled to an antenna, another is connected to a transmission circuit and the last pad is connected to a receive circuit. The filter is comprised of two sections: a transmission section and a receive section. The transmission and receive sections include resonators disposed on respective sides of the antenna pad. A first alternative signal path is disposed adjacent the ends of the transmission resonators. A second alternative signal path is disposed adjacent to the ends of the receive resonators. Each alternative signal path couples adjacent and non-adjacent resonators. A further feature of the filter of the present invention includes a shunt zero resonator for the transmission section. To the contrary, the present invention allows the elimination of a shunt zero resonator for the receive section of the filter.

Duplexer filter with an alternative signal path

A ceramic transverse-electromagnetic-mode filter having a resistive paste base and resistive paste layer and method of tuning same is provided. The ceramic filter includes a filter body (200) comprising a block of dielectric material and having top (202), bottom (204) and four side surfaces (206, 208, 210, 212) including vertical edges (214). The filter also has metallized through-holes providing transverse-electromagnetic-mode resonators (210). At least one vertical portion in proximity to the vertical edges (214) of the block on at least one of the side surfaces is unmetallized providing a resistive paste base (218). A resistive paste layer (219) of predetermined resistivity is deposited thereon. The resistive paste layer attenuates a set of parasitic spurious responses in the filter frequency response curve while simultaneously maintaining a desired transverse-electromagnetic-mode passband.

Suppression of spurious cavity modes using resistive paste on a ceramic

A ceramic transverse-electromagnetic-mode filter having a waveguide cavity mode frequency shifting void and method of tuning same is provided. The ceramic filter includes a filter body (200) comprising a block of dielectric material and having top (202), bottom (204) and four side surfaces (206, 208, 210, 212) including vertical edges (214). The filter also has metallized through-holes providing transverse-electromagnetic-mode resonators (216). At least one vertical portion in proximity to the vertical edges (214) of the block on at least one of the side surfaces is unmetallized providing a waveguide cavity mode frequency shifting void (218). The waveguide cavity mode frequency shifting void (218) shifts a set of parasitic spurious responses in the filter frequency response curve to a lower frequency while simultaneously maintaining a desired transverse-electromagnetic-mode passband.

Ceramic transverse-electromagnetic-mode filter having a waveguide cavity

A ceramic filter (10) is shown and described. The filter (10) has a filter body having top (14), bottom (16), and side surfaces (18, 20, 22 and 24) with through holes (26, 28) extending from the top (14) to the bottom surfaces (16) defining resonators. The surfaces are substantially covered with a conductive material defining a metallized layer, with the exception that the top surface (14) is substantially uncoated, and with an additional exception that a portion of a side surface is substantially uncoated in proximity to the top surface (14) and extending at least in proximity to between the resonators (26, 28), defining an unmetallized coupling region for electrically coupling the resonators. The filter (10) also has first and second input-output pads (34, 38) on a side surface for facilitating connection to a circuit board, for example.

Ceramic filter with ground plane features which provide transmission

A method of tuning a duplex filter (500). First, the center frequency of at least one filter of a duplex filter (10) is measured (502). Next, the difference between the measured center frequency and a desired center frequency is determined (504). And, third the duplex filter is tuned (506) by selectively removing a substantially planar layer of dielectric material for a top surface (14) of the filter (10), whereby the frequency characteristics are modified.

Method of tuning a ceramic duplex filter using an averaging step

A ceramic duplex filter is provided. The duplex filter (10) has a filter body (12) of a dielectric material, and has a top (14), bottom (16) and side surfaces (18, 20, 22, and 24) with through-holes extending from the top (14) to the bottom surface (16). Receptacles are positioned adjacent to the top surface (14) with a conductive material therein. The surfaces (16, 18, 20, 22 and 24) are substantially covered with a conductive material defining a metallized layer (25), with the exception that the top surface (14) is substantially unmetallized. The receptacles include a conductive layer of material to define a certain capacitance. And, coupling devices (94, 96 and 98) for coupling signals into and out of the duplex filter (10) are provided. Shunt, series and coupling capacitors are strategically positioned adjacent to the top surface (14), which help to facilitate tuning of the filter.

Ceramic duplex filter

A ceramic bandpass filter (10) that has transmission zeroes above the passband is accomplished without using the top patterning by a block structure that includes a localized mesa (26) formed at the top end of the block that provides increased capacitive coupling between the open circuits and the resonators (30, 32, and 34). This increased top end capacitance provided by the mesa (26) can provide high end or high side transmission zeroes to the characteristic transfer function of the filter.

Block filter having high-side passband transfer function zeroes

Interdigitation and surface mounting of a block filter that has at least a first resonator and that has at least a first pole and at least a first zero in its transfer function provides a surface mountable block filter having selectable frequency rejection response operation.

Surface mountable interdigital block filter having zero(s) in transfer

A method for bonding a first ceramic element and a second ceramic element utilizes a silver powder paste composed of silver particles dispersed in a volatile vehicle. A film of the paste is applied and dried onto a faying surface of each element. The elements are assembled with the films in contact and heated to sinter the silver particles into an integral silver layer that is bonded to the faying surfaces, thereby bonding the elements together. The method is particularly well suited to manufacturing a stripline filter, wherein the sintered layer not only bonds the ceramic elements, but also forms a metallic feature, such as a resonator, of the filter.

Silver paste sintering method for bonding ceramic surfaces

A dielectric block filter having a self aligning, top and shield is provided. Recesses are formed in at least one side of the block, which recess is dimensioned to accept a mating tab or side of a shield that substantially encloses the top end of the filter. The recess in the block in combination with the appropriately shaped tab produces the overall height of the filter and simplifies manufacturing by eliminating the need to hold or affix the shield to otherwise smooth sides of the block.

Low profile ceramic filter with self aligning shield

Improved Q factor for stripline and microstrip filters can be realized by increasing the thickness of conductive paths. Increased conductive paths in a stripline and microstrip filter can be realized by forming slots (20) in a block of dielectric material (12) which permit an increased thickness of transmission path thereby improving the Q factor of the material by reducing at least resistive losses.

High dielectric micro-trough line filter

A block-substrate dielectric filter with an a wider VHF range and better capacitive performance is set forth. A capacitive matrix situated in a dielectric substrate (102) that is operably attached to a block (104) filter provides more accurate shunt and series capacitances, and allows design of improved narrowband filters.

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San Diego, CA, United States of America

Truc G Hoang