Ceramic Monoblock Filter Quadruplet Cross-Coupling
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Solution Overview
Problem
Current ceramic monoblock filters face challenges in achieving symmetrical attenuation on both sides of the passband while maintaining compact size and cost-effectiveness, as existing triplet cross-coupling designs are limited in their ability to increase attenuation above the passband and require inductive coupling, which is not feasible with capacitive cross-coupling.
Innovation Solution
A ceramic monoblock filter design incorporating quadruplet cross-coupling and inductive direct-coupling features, utilizing conductive pads and external bypass transmission electrodes with inductive coupling means between resonators, allowing for capacitive cross-coupling and inductive direct-coupling to achieve balanced attenuation on both sides of the passband without increasing filter size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductive coupling is added to improve attenuation above the passband, then high frequency attenuation is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The inductive coupling structures (ground bars or notches) are merged with the existing resonator structure and top surface metallization pattern. The ground bars are positioned between resonators and integrated into the overall filter design, combining multiple functions into a unified structure rather than adding separate complex components
2Manufacturing precision
If ground bars or notches are added between resonators to provide inductive coupling, then inter-resonator coupling control is improved, but manufacturing complexity increases
Solution Approach 1:
The ground bars or notches are designed to be formed as integral parts of the ceramic block during the same manufacturing process that creates the resonator through-holes and top surface metallization. This merging of features into a single monoblock structure eliminates the need for separate assembly steps, maintaining ease of manufacture while achieving precise coupling control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves symmetrical filter response with improved attenuation on both low and high frequency sides, enhancing out-of-band rejection and allowing for fine adjustments in inter-resonator coupling without increasing manufacturing complexity or size.
Implementation Method 1
An external bypass transmission electrode is adapted to conductively connect the first pad to the second pad and provide a capacitive cross-coupling (i.e., alternative signal path) directly between the first and fourth resonators
Implementation Method 2
Inductive coupling means located between each of the first through fourth resonators are adapted to provide a direct coupling (i.e., direct signal path) between the first through fourth resonators
Implementation Method 3
First, second, third, and fourth spaced-apart resonators are defined by at least four adjacent resonator through-holes extending between the top and bottom surfaces of the block
Implementation Method 4
a block of dielectric material defined by top, bottom, and side surfaces
Data Source
AI summary
A ceramic monoblock filter including a direct signal path defined by at least four spaced-apart through-hole resonators in combination with ground bars extending between the through-hole resonators and a separate quadruplet cross-coupling alternate signal path defined by two conductive pads located adjacent the first and fourth ones of the through-hole resonators respectively and a separate external bridge member which interconnects and couples the two pads. The bridge member is preferably made of a material having a lower dielectric constant than the block of the filter. In one embodiment, the filter is a monoblock duplexer filter comprising respective transmit and receive sections each including at least four of the through-hole resonators, the ground bars, the two pads, and the bridge member. In the duplexer embodiment, additional through-hole resonators may define shunt zeros.