Variable Capacitor Isolation Circuit for I/O Port Coupling

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Solution Overview

Problem

As computing devices shrink in size to meet increasing performance demands, undesired coupling among I/O ports and wirings becomes a significant issue, leading to interference that degrades the performance of RF functions in devices like transceivers.

Innovation Solution

The implementation of an isolation circuit with a variable capacitor that can be dynamically tuned by a control module to adjust isolation between I/O ports and wirings, effectively reducing coupling and improving isolation without increasing physical distances between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If components are placed in closer proximity to reduce physical dimensions, then the device size is reduced, but coupling between I/O ports and wirings increases causing interference

Engineering Contradiction:
Improvedevice sizeVSAvoidcoupling interference
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

An isolation circuit is introduced as an intermediary component between the I/O ports and external wirings. This isolation circuit includes coupling elements that can be tuned to create destructive interference with the harmful coupling signals, thereby mitigating the interference while allowing the components to remain in close proximity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The coupling elements in the isolation circuit have tunable parameters (such as capacitance or inductance) that can be adjusted to optimize isolation performance. By changing these parameters, the isolation circuit can adapt to different operating conditions and frequency ranges, effectively reducing coupling interference without increasing physical distance.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If physical distance between I/O ports is increased to reduce coupling, then isolation improves, but device area increases

Engineering Contradiction:
Improveisolation performanceVSAvoiddevice area
Core Design Contradiction:
Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

Rather than increasing physical distance, an isolation circuit is placed between the I/O ports to provide electromagnetic isolation. This intermediary circuit uses tunable coupling elements to create signal cancellation effects that improve isolation performance without requiring additional physical space.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of increasing physical distance with an electromagnetic approach using tunable coupling elements. Instead of mechanically spacing components farther apart, the solution uses electromagnetic field manipulation through the isolation circuit to achieve the same isolation effect in a compact form factor.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If fixed isolation structures are used between I/O ports, then device complexity is reduced, but adaptability to different frequency ranges is limited

Engineering Contradiction:
Improveisolation circuit structureVSAvoidfrequency range adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The isolation circuit incorporates tunable coupling elements that can dynamically adjust their electrical characteristics. This allows the isolation performance to be adapted to different frequency ranges and operating conditions while maintaining a relatively simple circuit structure. The tunability is achieved through voltage-controlled or mechanically-adjustable elements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The coupling elements in the isolation circuit have adjustable parameters that can be changed to optimize performance for different frequency ranges. By modifying these parameters (such as capacitance values or inductance), the same isolation circuit structure can adapt to various operating conditions without requiring complex reconfiguration.

Inventive Principle:
Principle #35Parameter changes

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 solution significantly enhances isolation performance between I/O ports, achieving up to 58 dB of isolation at specific frequencies, thereby mitigating interference and maintaining the integrity of RF functions in compact computing devices.

Implementation Method 1

a variable capacitor electrically connected to a second I/O port is tuned to adjust isolation between a first I/O port and a third I/O port

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3912275B1Improved isolation among I/O ports
Publication Date: 2025.04.30 QUALCOMM INC
  • EP3912275B1 patent drawingFigure 1
  • EP3912275B1 patent drawingFigure 2
  • EP3912275B1 patent drawingFigure 3

AI summary

Methods and apparatuses to adjust isolation between I/O ports. An apparatus includes a die, a first input or output (I/O) port, a second I/O port, and a third I/O port. The second I/O port is between the first I/O port and the third I/O port. A variable capacitor is electrically connected to the second I/O port and is configurable to adjust isolation between the first I/O port and the third I/O port. A method includes performing, by a die, a first RF function via a first I/O port; tuning a variable capacitor electrically connected to a second I/O port to adjust isolation between the first I/O port and a third I/O port, the second I/O port being between the first I/O port and the third I/O port; and performing, by the die, a second RF function via a third I/O port.