Bias Tee Nested Inductor Isolation RF Signal Integrity

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Solution Overview

Problem

Conventional bias tee arrangements in RF filter apparatus fail to provide sufficient isolation between DC and low frequency control signals and RF communication signals for frequencies below 1GHz, leading to intermodulation distortion and interference.

Innovation Solution

Incorporating a second inductor within a sleeve or tube member in the bias tee apparatus, which enhances isolation between the DC bypass pathway and the RF communication signal pathway without increasing space or component count, using a combination of capacitors and inductors to prevent RF leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional bias tee arrangement with a single inductor and capacitor is used, then the structure is simple and space is saved, but insufficient isolation between DC bypass pathway and RF communication signal pathway occurs for frequencies below 1GHz

Engineering Contradiction:
Improveisolation between pathwaysVSAvoidcomponent count and structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent places a second inductor inside the sleeve or tube member of the first capacitor, creating a nested configuration where one component is housed within another. This nesting approach increases isolation performance by adding another inductive element in the RF signal pathway without increasing the overall footprint or component count, thereby resolving the contradiction between improved isolation and device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention utilizes the spatial dimension within the existing capacitor sleeve structure to accommodate an additional inductor. By exploiting the three-dimensional space already present in the bias tee assembly, the patent adds isolation functionality without requiring additional mounting space or increasing the structural complexity from a planar perspective.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If additional components are added to improve isolation, then RF signal integrity is improved, but space and cost increase

Engineering Contradiction:
ImproveRF signal integrityVSAvoidspace and cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent combines the second inductor with the first capacitor by placing the inductor inside the capacitor's sleeve structure. This merging approach allows two functional components to occupy the same physical space, thereby improving RF signal integrity through enhanced isolation without requiring additional mounting space or increasing manufacturing complexity and cost.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

By nesting the second inductor within the first capacitor's sleeve, the patent achieves space-efficient component arrangement. The nested configuration allows the additional isolation component to be accommodated within the existing structural envelope, avoiding increases in overall device volume, material usage, and associated costs.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If a second inductor is placed inside the capacitor sleeve, then isolation is significantly improved without increasing space, but manufacturing complexity increases

Engineering Contradiction:
Improveisolation performanceVSAvoidassembly process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent incorporates the second inductor during the capacitor assembly process, where the inductor is placed inside the sleeve before the capacitor is fully assembled or sealed. This preliminary action ensures that the nested configuration is established during manufacturing rather than requiring post-assembly installation, thereby minimizing additional manufacturing steps and maintaining ease of production.

Inventive Principle:
Principle #10Preliminary action

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 significantly reduces intermodulation distortion, improves RF signal integrity, and allows for more flexible cavity design in RF filter apparatus, reducing the need for additional components and saving space and cost.

Implementation Method 1

The DC bypass pathway includes at least a first inductor means for helping to prevent the passage of one or more RF communication signals therealong

Methodology Applied
Scientific EffectElectrical Impedance: Electrical Resistance

Implementation Method 2

The RF communication signal pathway includes at least first and second capacitor means for helping to prevent the passage of DC and control signals therealong

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

at least one of the at least first or second capacitor means includes a sleeve or tube member and at least a second inductor means is located in an interior of the sleeve or tube member

Methodology Applied
Scientific EffectElectromagnetic Isolation: Electromagnetic Induction

Data Source

PatentEP3972048A1Bias tee apparatus and method of use thereof
Publication Date: 2022.03.23 RADIO DESIGN LTD
  • EP3972048A1 patent drawingFigure 1a~1b
  • EP3972048A1 patent drawingFigure 2a~2b
  • EP3972048A1 patent drawingFigure 3a~3d

AI summary

Bias tee apparatus is provided for radio frequency (RF) apparatus. The bias tee apparatus includes an input pathway for the passage of one or more radio frequency (RF) communication signals and direct current (DC) therealong in use. The input pathway divides into a DC bypass pathway to allow the passage of direct current (DC) therealong in use and an RF communication signal pathway for the passage of one or more RF communication signals therealong in use. The DC bypass pathway including at least a first inductor means for helping to prevent the passage of one or more RF communication signals therealong in use, and the RF signal pathway including at least first and second capacitor means for helping to prevent the passage of DC therealong in use. At least one of the at least first or second capacitor means includes a sleeve or tube member and at least a second inductor means is located in an interior of the sleeve or tube member.