Contactless Data Reception Cancellation Circuit

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Solution Overview

Problem

Existing contactless communication systems face challenges in achieving high bit rate data transfer due to distortion and attenuation caused by the high-Q resonance circuit, which optimizes energy transfer but negatively impacts data transfer speeds.

Innovation Solution

Incorporating a separate pickup antenna and cancellation circuit in both the reader and the contactless card to compensate for the transmission antenna field, allowing the contactless card antenna field to remain undistorted and enabling high-quality data transmission at high baudrates by subtracting the reader's transmission antenna voltage from the detected field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the reader's high-Q resonance circuit is used to optimize energy transfer, then energy transfer efficiency is improved, but data transfer rate deteriorates due to attenuation of subcarrier frequencies

Engineering Contradiction:

Improveenergy transfer efficiencyVSAvoiddata transfer rate

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The system separates the detection function into a dedicated pickup antenna distinct from the transmission antenna. The pickup antenna detects both the transmission field and the modulated field, while the cancellation circuit selectively removes the transmission field component. This segmentation allows the high-Q resonance circuit to maintain energy efficiency while the separate detection path preserves data signal integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cancellation circuit acts as an intermediary that processes the detected field signal by subtracting the transmission antenna field component. This intermediary processing step removes the harmful attenuation effect of the high-Q resonance circuit on the data signal while preserving the energy optimization benefits for power transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If subcarrier frequencies are increased to speed up data communication, then data transfer rate is improved, but signal quality deteriorates due to attenuation by the high-Q resonance circuit

Engineering Contradiction:

Improvedata transfer rateVSAvoidsignal quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

By separating the detection function into a dedicated pickup antenna and implementing field cancellation, the system creates an independent detection path that is not subject to the same attenuation limitations as the traditional transmission antenna detection. This allows high subcarrier frequencies to be used without signal quality degradation.

Inventive Principle:

Principle #1Segmentation

3Difficulty of detecting and measuring

If the transmission antenna field is detected along with the contactless card antenna field, then detection sensitivity is improved, but measurement precision deteriorates due to field distortion and attenuation

Engineering Contradiction:

Improvedetection sensitivityVSAvoidfield measurement accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The cancellation circuit extracts and removes the transmission antenna field component from the combined detected field signal. This leaves only the contactless card antenna field component, providing a clean, undistorted measurement of the data signal while maintaining the benefits of using the pickup antenna for detection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses feedback from the known transmission antenna field characteristics to generate a cancellation signal that is subtracted from the detected field. This feedback mechanism enables precise removal of the transmission field component, maintaining measurement precision while preserving detection sensitivity.

Inventive Principle:

Principle #23Feedback

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 communication quality by eliminating distortion and attenuation, allowing for faster data communication and higher baudrates without compromising energy transfer.

Implementation Method 1

a pickup antenna Lpickup-PCD configured to detect a magnetic field, which is proportional to a sum of a field of the transmission antenna LPCD and a field of the contactless card antenna LPICC

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

antenna LPICC and resonance capacitor CPICC form a resonance circuit, and are configured to provide contactless card 720 with a specific resonance frequency

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS8905310B2Contactless data reception using a cancellation circuit

Publication Date: 2014.12.09 INFINEON TECHNOLOGIES AG

AI summary

A contactless device including a transmission antenna configured to transmit a transmission signal; a pickup antenna configured to detect a field generated by a pickup signal, which comprises a response signal transmitted from another contactless device and the transmission signal; and a cancellation circuit configured to subtract a voltage of the transmission antenna from a voltage of the pickup antenna.