RF Monoblock Filter with Outward Walls for Harmonic Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF signal filters face challenges in providing sufficient attenuation at harmonic frequencies, which are integer multiples of the passband frequencies, while also needing to maintain compact size and low insertion loss to accommodate higher frequencies and smaller device sizes.
Innovation Solution
A dielectric block filter design with a recessed top surface pattern and cavity structure that includes metallized and unmetallized areas, resonator pads, and electrodes, which enhances capacitive and inductive coupling to improve signal rejection and harmonic suppression without increasing footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external metallic shields are added to cancel parasitic coupling and achieve acceptable stopbands, then signal rejection improves, but device complexity and footprint increase
Solution Approach 1:
The patent integrates the shielding function directly into the filter body by forming conductive walls that extend from the resonator cavities. These walls are monoblock-formed with the filter substrate, eliminating the need for separate external shields. The walls perform dual functions: they provide structural support for electrode placement and simultaneously cancel parasitic coupling between non-adjacent resonators, achieving stopband performance without adding external components.
Solution Approach 2:
The conductive walls serve multiple functions within a single structural element. They act as: (1) shielding barriers to cancel parasitic coupling, (2) support structures for input and output electrodes, (3) definers of the filter's external footprint, and (4) integrators of the metallization pattern. This multi-functionality eliminates the need for separate external shields and reduces overall device complexity.
2Reliability
If more space-taking resonators are added to provide improved signal rejection, then attenuation at harmonic frequencies improves, but device footprint increases
Solution Approach 1:
The patent extends the filter structure vertically by forming conductive walls that rise from the planar resonator cavities. This vertical dimension provides additional space for electrode placement and for the walls themselves to act as shielding elements. By utilizing the vertical dimension rather than expanding horizontally, the filter achieves improved harmonic suppression and electrode integration without increasing the device footprint.
3Reliability
If greater insertion loss is allowed to provide improved signal rejection, then attenuation at harmonic frequencies improves, but signal quality deteriorates
Solution Approach 1:
The patent optimizes the electrical parameters of the conductive walls, including their height, width, and position relative to the resonators. By carefully controlling these geometric parameters, the walls provide effective parasitic coupling cancellation at harmonic frequencies while maintaining minimal impact on the passband signal. The metallization pattern on the walls is also optimized to achieve the desired attenuation without excessive insertion loss.
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 improved attenuation and sharper frequency response, allowing for better harmonic suppression and stability across multiple frequency bands with reduced electromagnetic interference, eliminating the need for external shielding and enabling flexible electrode placement.
Implementation Method 1
the resonators are formed by typically cylindrical passages, called through-holes, extending through the block... The reactive coupling between adjacent resonators is dictated, at least to some extent, by the physical dimensions of each resonator, by the orientation of each resonator with respect to the other resonators, and by aspects of the top surface metallization pattern
Implementation Method 2
The reactive coupling between adjacent resonators is dictated, at least to some extent, by the physical dimensions of each resonator, by the orientation of each resonator with respect to the other resonators, and by aspects of the top surface metallization pattern
Implementation Method 3
One or more walls or posts extend outwardly and upwardly away from the peripheral edges of the top surface to define a top filter cavity and a peripheral outer rim... eliminating the need for external shielding
Data Source
AI summary
An electrical signal filter defined by a block of dielectric material with a top surface, a bottom surface, side surfaces, and through-holes extending between the top and bottom surfaces. In one embodiment, a plurality of walls extend outwardly from the top surface to define a peripheral rim and filter cavity. A pattern of metallized and unmetallized areas is defined on selected surfaces of the block including an area of metallization that covers at least a portion of the top surface and at least one of the walls to define at least one input/output electrode on the wall. In one embodiment, a pair of input/output electrodes are formed on a pair of posts defined on one of the walls and the filter is adapted for mounting to a printed circuit board with the rim of the walls against the board and the posts coupled to respective input and output pads on the board.