LC Tank Antenna Coil Tuning via Channel Sounding Signal

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Solution Overview

Problem

Existing antenna coil tuning methods for Near-Field Magnetic Induction (NFMI) and Near Field Communication (NFC) systems are inefficient, requiring multiple tone measurements and significant time for tuning, which reduces data rate and increases power consumption due to the need for continuous antenna circuit driving during the tuning process.

Innovation Solution

An integrated circuit with an inductive-capacitive (LC) tank antenna circuit that uses a single channel sounding signal (CSS) to estimate the tank response and adjust the reactance to resonate at a predetermined carrier frequency, allowing for fast and efficient tuning by determining the oscillation frequency and adjusting the variable capacitor or inductance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple tone measurements are used for antenna coil tuning, then tuning accuracy is improved, but tuning time and power consumption increase

Engineering Contradiction:
Improvetuning accuracyVSAvoidtuning time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing a single channel sounding signal measurement before actual data transmission to pre-determine the oscillation frequency and adjust the variable capacitor accordingly. This preliminary tuning action eliminates the need for multiple measurements during operation, thereby reducing tuning time while maintaining accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts only the essential information needed for tuning by using a single channel sounding signal instead of multiple tone measurements. By taking out only the necessary frequency identification step and removing unnecessary iterative measurements, the system achieves accurate tuning with minimal time loss.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If multiple tone measurements are used for antenna coil tuning, then tuning accuracy is improved, but power consumption increases

Engineering Contradiction:
Improvetuning accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent performs the tuning measurement as a preliminary action before data transmission begins. By completing the frequency identification and capacitor adjustment in advance using a single channel sounding signal, the system avoids continuous power-consuming measurements during operation, thereby reducing overall power consumption while maintaining tuning accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts only the essential frequency information from a single measurement rather than performing multiple measurements. This extraction approach obtains sufficient tuning data with minimal energy expenditure, eliminating wasteful repeated measurements that would increase power consumption.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If iterative tuning measurements are performed, then frequency identification accuracy is improved, but data rate decreases

Engineering Contradiction:
Improvefrequency identification accuracyVSAvoiddata rate
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent performs frequency identification as a preliminary action using a single channel sounding signal before actual data transmission. This one-time preliminary measurement establishes accurate frequency identification without requiring iterative measurements during data transmission, thereby maintaining high data rates while ensuring frequency accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts the necessary frequency identification information from a single channel sounding signal measurement rather than requiring multiple iterative measurements. This extraction of essential information enables accurate frequency identification with minimal interruption to data transmission, preserving high data rates.

Inventive Principle:
Principle #2Taking out (Extraction)

4Measurement precision

If continuous antenna circuit driving is performed during tuning, then tuning measurements can be completed, but power consumption increases

Engineering Contradiction:
Improvetuning measurement completionVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent completes all necessary tuning measurements as a preliminary action before actual operation using a single channel sounding signal. This preliminary completion of measurements eliminates the need for continuous driving during data transmission, thereby reducing power consumption while ensuring accurate tuning is achieved.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts sufficient tuning information from a single measurement rather than requiring continuous measurements. This extraction approach obtains the necessary frequency and capacitance adjustment data with minimal antenna circuit driving, reducing power consumption while completing the tuning objective.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enables rapid and accurate tuning of the antenna coil, reducing power consumption and system throughput impact, allowing for immediate oscillation frequency identification without iterations, and providing high accuracy and flexibility in bandwidth selection.

Implementation Method 1

an inductive-capacitive (LC) tank antenna circuit designed to operate at a predetermined carrier frequency

Methodology Applied
Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

Near field magnetic induction (NFMI)

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

a controller to adjust a reactance of the LC tank antenna circuit to resonate the LC tank antenna circuit and change the oscillation frequency to the predetermined carrier frequency

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3407503B1Antenna coil tuning mechanism for magnetic communication
Publication Date: 2023.12.20 NXP BV
  • EP3407503B1 patent drawingFigure 1~2
  • EP3407503B1 patent drawingFigure 3~4

AI summary

Disclosed is an integrated circuit for a near-field radio, including an inductive-capacitive (LC) tank antenna circuit designed to operate at a predetermined carrier frequency, the tank LC tank antenna circuit including a variable capacitor and an antenna element, a transmitter configured to output a channel sounding signal (CSS) to the LC tank antenna circuit, a receiver to receive the CSS and a tank response from the LC tank antenna circuit, a tank response estimator to extract the tank response of the LC tank antenna circuit by removing the CSS from the received signal and determining an oscillation frequency of the LC tank antenna circuit, and a controller to adjust a reactance of the LC tank antenna circuit to resonate the LC tank antenna circuit and change the oscillation frequency to the predetermined carrier frequency.