Crosstalk Reduction in Receiver Inductive Loop Using Capturing Loop

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Solution Overview

Problem

Inductive loop digital isolators face significant crosstalk issues when multiple channels transmit data in different directions, leading to data transmission errors and manufacturing challenges, as existing solutions either increase space, reduce circuit values, or complicate manufacturing with vertical loop stacking.

Innovation Solution

The design features coplanar transmitter and receiver inductive loops with a large conventional loop and a small loop portion inside adjacent channels, sized to minimize magnetic flux interference, allowing for a densely packed and cost-effective arrangement while maintaining minimal crosstalk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If inter-channel spacing is increased to minimize crosstalk, then crosstalk is reduced, but device area increases

Engineering Contradiction:

ImprovecrosstalkVSAvoiddevice area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The receiver inductive loop is segmented into two distinct portions: a large conventional loop portion for receiving signal and a small loop portion positioned inside the adjacent channel's transmitter loop for crosstalk cancellation. This segmentation allows each portion to perform its specific function optimally while maintaining compact device area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The small loop portion acts as an intermediary element that generates a counter-phase signal to cancel the crosstalk from adjacent channels. By positioning this small loop inside the adjacent transmitter loop and sizing it appropriately, it captures the interfering magnetic flux and produces a canceling voltage that subtracts from the crosstalk.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If circuit values are reduced to minimize crosstalk, then crosstalk is reduced, but signal quality deteriorates

Engineering Contradiction:

ImprovecrosstalkVSAvoidsignal quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention changes the geometric parameter of the receiver loop by adding a small loop portion with specific area ratio (typically 1:10 to 1:20 compared to the large loop portion). This parameter change enables crosstalk reduction through magnetic flux cancellation without requiring changes to circuit values that would compromise signal quality.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If vertical stacking of receive and transmit loops is used to minimize crosstalk, then crosstalk is reduced, but manufacturing complexity increases

Engineering Contradiction:

ImprovecrosstalkVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Instead of moving to vertical stacking in the third dimension, the invention addresses crosstalk within the planar dimension by strategically positioning a small loop portion inside the adjacent channel's transmitter loop area. This maintains coplanar manufacturing simplicity while achieving crosstalk reduction through clever spatial arrangement.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 crosstalk, enabling a more compact and cost-effective manufacturing process without compromising impedance or signal-noise ratio, thus improving data transmission reliability and manufacturing efficiency.

Implementation Method 1

the small loop portion that is located inside the transmitter inductive loops of the adjacent channels... This size relationship results in the voltage of the small loop portion being very close but opposite in sign to the voltage in the conventional loop portion

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10855333B2Crosstalk reduction in receiver inductive loop using capturing loop in transmitting inductive loop

Publication Date: 2020.12.01 TEXAS INSTRUMENTS INC

AI summary

An inductively coupled multi-channel digital isolator where the transmitter and receiver inductive loops of a given channel are coplanar. In the case where two adjacent channels flow data in opposite directions, the receiver inductive loops of a given channel include a large, generally conventional loop portion and a small loop portion that is located inside the transmitter inductive loops of the adjacent channels. The sizes of the small loop portion and the conventional loop portion are generally in the ratio of the magnetic flux in the conventional loop portion to the magnetic flux in the transmitter inductive loop. This size relationship results in the voltage of the small loop portion being very close but opposite in sign to the voltage in the conventional loop portion. As a result, there is minimal crosstalk from the transmitter inductive loop of one channel to the receiver inductive loop of the adjacent channel.