Integrated Dielectric Filter Layout for Harmonic Suppression
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Solution Overview
Problem
Dielectric filters in communications devices face challenges with poor harmonic suppression and high layout space consumption due to the difficulty in matching between different filters and the need for additional low-pass filters.
Innovation Solution
A dielectric filter design incorporating both wideband and narrowband filtering structures within the same dielectric body, featuring a conductive layer-covered groove and resonators, which adjusts frequency positions and harmonic suppression capabilities, reducing the need for separate low-pass filters and minimizing layout space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low-pass filter is cascaded with the dielectric filter to improve harmonic suppression, then harmonic suppression capability is improved, but device complexity and layout space consumption increase
Solution Approach 1:
The patent combines the wideband filtering structure and narrowband filtering structure into a single integrated dielectric filter body. The wideband structure suppresses far-end harmonics while the narrowband structure provides precise frequency screening, eliminating the need for cascaded low-pass filters and reducing overall device complexity
Solution Approach 2:
The dielectric filter body performs multiple functions simultaneously: the wideband filtering structure handles harmonic suppression across a broad frequency range, while the narrowband filtering structure provides precise frequency selection. This multi-functional integration replaces what would traditionally require separate cascaded filters
2Object-affected harmful factors
If a low-pass filter is cascaded with the dielectric filter to improve harmonic suppression, then harmonic suppression capability is improved, but layout space consumption increases
Solution Approach 1:
Both filtering structures are integrated within the same dielectric filter body, sharing the same physical space and mounting footprint. This consolidation eliminates the need for separate low-pass filter components and their associated mounting space on the PCB
Solution Approach 2:
The narrowband filtering structure is nested within the same dielectric body that contains the wideband filtering structure. The two structures coexist in a nested arrangement, maximizing space utilization and minimizing the overall footprint of the filter assembly
3Object-affected harmful factors
If different filters are cascaded to improve harmonic suppression, then harmonic suppression capability is improved, but matching difficulty between filters increases
Solution Approach 1:
The wideband and narrowband filtering structures are manufactured as a single integrated dielectric filter body, eliminating the need for separate filter assemblies and their associated matching problems. The structures work together as a unified system with inherent impedance matching
Solution Approach 2:
The filter body is segmented into functional regions (wideband filtering structure and narrowband filtering structure) that are manufactured separately in the molding process but function together as an integrated unit, simplifying both manufacturing and matching
4Object-affected harmful factors
If separate filters are used to improve harmonic suppression, then harmonic suppression capability is improved, but manufacturing complexity increases
Solution Approach 1:
Both filtering structures are manufactured as a single integrated dielectric filter body using one molding process, eliminating the need for separate manufacturing, assembly, and testing of multiple filter components
Solution Approach 2:
The single dielectric filter body serves multiple functions (wideband filtering and narrowband filtering) that would traditionally require separate manufactured components, simplifying the manufacturing process while maintaining comprehensive filtering capability
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
Enhances harmonic suppression and frequency precision, simplifies manufacturing, and reduces echo deterioration and layout space requirements by integrating filtering structures within a single dielectric body.
Implementation Method 1
The first resonator includes a through hole and a loop. The through hole penetrates the bottom of the groove and a second surface of the dielectric body, and a hole wall of the through hole is covered with the conductive layer. The loop is located on a bottom surface of the groove, disposed around an opening of the through hole
Implementation Method 2
The side surface of the groove and a part, other than the loop, of the bottom surface of the groove are covered with the conductive layer
Implementation Method 3
The narrowband filtering structure includes at least one second resonator, and the second resonator includes a blind hole disposed on the first surface or the second surface of the dielectric body. A hole wall and a bottom surface of the blind hole are covered with the conductive layer
Implementation Method 4
The groove is disposed on a first surface of the dielectric body, and the groove is configured to adjust a frequency position of the passband of the wideband filtering structure
Implementation Method 5
The adjustment through hole penetrates the bottom of the groove and the second surface of the dielectric body. The adjustment through hole is configured to adjust a harmonic suppression capability of the dielectric filter
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Embodiments of this application provide a dielectric filter, a duplexer, and a communications device, relate to communications device components, and intend to resolve problems of a great difficulty in matching between different filters and high layout space consumption that are caused by addition of a low-pass filter cascaded with the dielectric filter. The dielectric filter includes a dielectric body, and a wideband filtering structure and a narrowband filtering structure that are disposed in the dielectric body. The wideband filtering structure includes a groove and at least one first resonator. The groove is disposed on a first surface of the dielectric body and is configured to adjust a frequency position of a passband of the wideband filtering structure. The first resonator includes a through hole and an open loop. The through hole penetrates the bottom of the groove and a second surface of the dielectric body. The open loop is located on a bottom surface of the groove and is disposed around an opening of the through hole. The narrowband filtering structure includes at least one second resonator, and the second resonator includes a blind hole disposed on the second surface of the dielectric body. The first surface and the second surface of the dielectric body are disposed oppositely.