Band-pass filter element with integrated electromagnetic shielding
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Solution Overview
Problem
The challenge is to reduce the thickness of a band-pass filter element and its layered substrate structure while maintaining effective performance, particularly for WCDMA reception signals, as existing block-type dielectric filters are large and difficult to miniaturize, and surface acoustic filters have low power resistance, making them unsuitable for high-power GSM transmission signals.
Innovation Solution
A band-pass filter element is designed without an electromagnetic shield conductor layer, using a layered substrate with a grounding conductor layer that functions as an electromagnetic shield, allowing for reduced thickness and improved integration within a high frequency module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a block-type dielectric filter is used as a WCDMA reception BPF, then the filter achieves low power loss and high resistance to power, but the filter becomes relatively large in dimensions and difficult to reduce in thickness
Solution Approach 1:
The invention divides the filter structure into separate functional layers: a layered substrate containing the resonator structure and a distinct electromagnetic shield layer positioned at a specific distance from the resonator. This segmentation allows the resonator to be thin while maintaining the necessary shielding function separately, resolving the contradiction between thinness and power resistance.
Solution Approach 2:
The invention introduces a dielectric layer as an intermediary between the resonator and the electromagnetic shield. This intermediate dielectric layer enables precise control of the distance between the resonator and shield, allowing optimization of both the resonator's Q factor (by maintaining appropriate spacing) and the shield's power protection function, thus resolving the thickness contradiction.
2Adaptability or versatility
If a block-type dielectric filter is mounted on the front end module substrate, then the filter can be included in the front end module, but the overall module thickness increases and integration is reduced
Solution Approach 1:
The invention merges the band-pass filter structure with the layered substrate by forming the resonator and electromagnetic shield as integrated layers within the substrate itself. This integration eliminates the need for separate filter components, achieving both module integration and reduced overall thickness simultaneously.
Solution Approach 2:
The invention transitions from a three-dimensional block-type filter to a planar layered structure within the substrate. By arranging the resonator and shield in alternating layers within the substrate thickness, the filter achieves compact integration without increasing the module's overall footprint or requiring additional mounting space.
3Reliability
If the distance between the resonator and electromagnetic shield is reduced to decrease capacitance, then the resonator's Q increases, but the shield becomes less effective and power loss increases
Solution Approach 1:
The invention optimizes the distance parameter between the resonator and electromagnetic shield to achieve the best balance between Q factor and power loss. By carefully controlling this distance (not too close, not too far), the design achieves high Q while maintaining effective shielding and low power loss.
Solution Approach 2:
The invention uses a composite structure with specific dielectric materials positioned between the resonator and shield. This composite arrangement allows the electric field to be contained effectively while maintaining appropriate spacing, thus achieving both high Q and low power loss simultaneously.
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
This configuration enables a thinner band-pass filter element and high frequency module, enhancing the Q of resonators and reducing the overall profile, while allowing for easier adjustment of the high frequency module's characteristics, thus addressing the size and performance limitations of previous solutions.
Implementation Method 1
the conductor layer for grounding that the layered substrate includes is opposed to the band-pass filter element and thereby functions as an electromagnetic shield for the band-pass filter element
Implementation Method 2
conductor layers for band-pass filter and dielectric layers for band-pass filter that are stacked and that implement a function of a band-pass filter
Data Source
AI summary
A high frequency module incorporates a layered substrate, a plurality of elements mounted on a top surface of the layered substrate, and a metallic casing that covers these elements. The plurality of elements mounted on the top surface of the layered substrate include a band-pass filter element. The band-pass filter element includes a plurality of conductor layers for band-pass filter and a plurality of dielectric layers for band-pass filter that implement a function of a band-pass filter, but does not include any conductor layer that functions as an electromagnetic shield. A conductor layer for grounding that the layered substrate includes and the casing are each opposed to the band-pass filter element, and thereby function as an electromagnetic shield for the band-pass filter element.