Battery Pack RF Interference Filtering
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Solution Overview
Problem
Lithium-ion battery packs in mobile wireless communications devices cause interference with the device antenna due to radio frequency energy coupling, leading to issues like audible buzzing, data signal interference, and degraded antenna performance.
Innovation Solution
A self-contained rechargeable battery pack with internal filter elements, such as ferrite beads and capacitors, are positioned within the battery casing to couple with the internal battery circuitry, providing enhanced filtering and grounding to reduce RF energy coupling and improve antenna performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional battery packs are used in mobile wireless communications devices, then the device can operate with basic power supply functionality, but RF energy coupling causes interference with the antenna leading to audible buzzing, data signal interference, and degraded antenna performance
Solution Approach 1:
Filter elements (capacitors and inductors) are introduced as intermediary components between the battery pack and the antenna system. These filter elements block RF energy coupling paths while allowing normal power supply operation, thereby eliminating antenna interference without fundamentally changing the battery pack structure
Solution Approach 2:
The harmful RF energy coupling is extracted and isolated from the main battery pack system by positioning filter elements at strategic locations. The filter elements remove the interfering RF energy paths while preserving the essential power supply function of the battery pack
2Reliability
If filter elements are added to the battery pack to reduce RF energy coupling, then antenna performance is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The filtering function is segmented into multiple discrete filter elements (capacitors and inductors) that can be independently selected and positioned. This segmentation allows for modular assembly and easier manufacturing compared to integrating a complex filter circuit into the battery pack
Solution Approach 2:
Rather than implementing a complex comprehensive filtering system, the solution uses simple discrete filter elements positioned at key locations. This partial action approach provides sufficient RF interference reduction while keeping manufacturing complexity low
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 solution significantly reduces RF energy interference, eliminating audible buzzing, improving data signal reception, and enhancing antenna performance by up to 10 to 30 dB compared to conventional battery packs.
Implementation Method 1
Each of the filter elements may include at least one ferrite bead
Implementation Method 2
Each of the filter elements may include at least one capacitor
Data Source
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AI summary
A mobile wireless communications device may include a portable device housing, wireless communications circuitry carried by the portable device housing, and a self-contained rechargeable battery pack carried by the portable housing for powering the wireless communications circuitry. The self-contained rechargeable battery pack may include a battery casing, at least one internal battery cell carried within the battery casing, internal battery circuitry carried within the battery casing, and at least one internal filter element carried within the battery casing and coupled to the internal battery circuitry.