Galvanic Isolation with Common Mode Noise Suppression Capacitors

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Solution Overview

Problem

Conventional methods for galvanic isolation, such as optical and transformer-based systems, are inefficient due to high costs, large size, and significant power consumption, and fail to effectively suppress common mode noise in inductive communication systems, which can overwhelm desired signals and disable communication links.

Innovation Solution

The implementation of an inductive communication system with isolated coils and capacitive structures that include CM noise suppression capacitance between each coil and its respective ground, reducing the impact of common mode noise through voltage division, thereby enhancing transient noise immunity and maintaining effective communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional galvanic isolation techniques (optical isolators, transformer-based isolators) are used, then electrical isolation between circuits is achieved, but the device size, cost, and power consumption increase significantly

Engineering Contradiction:

Improvegalvanic isolation effectivenessVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the essential function of galvanic isolation from complex conventional systems (optical isolators, transformers) and implements it using a simplified capacitive coupling structure with common mode noise suppression, removing unnecessary components while maintaining isolation effectiveness

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the isolation mechanism from magnetic coupling (transformers) or light transmission (optical isolators) to capacitive coupling with specific common mode noise suppression parameters, achieving isolation with different physical principles that require smaller device dimensions

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional galvanic isolation techniques are used, then electrical isolation is provided, but the cost and power consumption increase

Engineering Contradiction:

Improvegalvanic isolation effectivenessVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The capacitive coupling structure with common mode noise suppression capacitors provides galvanic isolation that is inherently energy-efficient, using passive components that do not require significant power consumption for operation, unlike active isolation components in conventional systems

Inventive Principle:

Principle #25Self-service

3Productivity

If inductive communication is implemented without common mode noise suppression, then communication between isolated circuits is enabled, but common mode noise overwhelms desired signals and disables communication

Engineering Contradiction:

Improvecommunication effectivenessVSAvoidcommon mode noise

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful common mode noise into a manageable parameter by adding common mode noise suppression capacitors that specifically target and reduce CM noise while preserving the differential mode communication signals, effectively turning a communication-blocking problem into a solved design feature

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The common mode noise suppression capacitors act as intermediary elements between the primary and secondary coils, mediating the electromagnetic coupling to filter out common mode noise while allowing desired communication signals to pass through the galvanic isolation barrier

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach provides improved galvanic isolation and noise immunity, allowing for reliable communication between circuits with reduced interference from parasitic capacitance-induced noise, thus enhancing the performance and efficiency of inductive communication systems.

Implementation Method 1

a first capacitor coupled between the first coil and a first voltage reference. The second coil is aligned with the first coil across a gap

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the inherent parasitic capacitance between the coils

Methodology Applied

Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 3

The first coil and the second coil are aligned with each other across a gap

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10992346B2Systems and devices with common mode noise suppression structures and methods

Publication Date: 2021.04.27 NXP USA INC

AI summary

An embodiment of a transformer-based system or galvanic isolation device includes a first coil, a second coil aligned with the first coil across a gap, and a first capacitor coupled between the first coil and a first voltage reference. A first electrode of the first capacitor may be formed from a conductive electrode structure that is electrically isolated from the first coil, and a second electrode of the first capacitor may be formed from at least a portion of the first coil. The system or device also may include a second capacitor coupled between the second coil and a second voltage reference. The first and second coils may form portions of first and second IC die, respectively, and the system or device may also include one or more dielectric components within the gap between the IC die, where the dielectric component(s) are positioned directly between the first and second coils.