Single-Chip NFC Antenna Switching for Accurate Tag Localization

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Solution Overview

Problem

Existing NFC systems face challenges in accurately locating tag positions due to increased costs and reduced performance caused by the use of multiple antennas and analog or RF switches, which lead to coupling and reduced accuracy.

Innovation Solution

Implementing a single-chip NFC reader with MOS switch circuits to control connections between multiple single-ended antennas, enabling and disabling them separately to prevent coupling and improve location accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple antennas are used for NFC tag location, then location coverage is improved, but antenna coupling occurs and location accuracy deteriorates

Engineering Contradiction:

Improvelocation coverageVSAvoidlocation accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent implements dynamic antenna switching where the NFC reader alternates between different antennas in time-division multiplexed fashion. Each antenna is activated sequentially rather than simultaneously, preventing coupling while maintaining coverage. The system dynamically selects which antenna to use based on temporal scheduling, resolving the contradiction between coverage and accuracy.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs periodic activation of different antennas, cycling through the antenna array in a structured sequence. This periodic switching ensures that each antenna has dedicated time slots for transmission and reception, eliminating continuous coupling interference while preserving overall spatial coverage through the periodic rotation of active elements.

Inventive Principle:

Principle #19Periodic action

2Adaptability or versatility

If analog or RF switches are used to control multiple antennas, then antenna switching capability is improved, but cost and device complexity increase

Engineering Contradiction:

Improveantenna switching capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the analog/RF switch component from the traditional antenna switching architecture. Instead of using dedicated switching hardware, the system achieves antenna selection through direct digital control of antenna activation states, removing the complex analog switching layer while retaining the essential antenna switching capability through simplified digital logic.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system replaces the mechanical/analog switch-based antenna selection mechanism with a digital control approach. Rather than using physical or analog switching components that require precise hardware control, the patent uses digital signal processing and software-controlled antenna activation, substituting complex hardware mechanics with simpler digital control logic.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If analog or RF switches are used for antenna control, then antenna switching is enabled, but operational cost increases

Engineering Contradiction:

Improveantenna switchingVSAvoidoperational cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent adopts a cost-effective approach by replacing expensive analog/RF switch components with simpler, lower-cost digital control circuitry. The system uses economical digital logic elements and software control instead of costly analog switching hardware, reducing the bill of materials cost while maintaining the required antenna switching functionality for multi-antenna operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

The solution allows for cost-effective and accurate localization of multiple tags by preventing antenna coupling, enhancing the performance of NFC readers and reducing operational costs.

Implementation Method 1

Implementing a single-chip NFC reader with MOS switch circuits to control connections between multiple single-ended antennas

Methodology Applied

Scientific EffectMOS switch:

Implementation Method 2

The NFC reader may use an antenna to detect the modulation and then decode the data

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4711974A1Systems and methods for locating tag positions using a single-chip

Publication Date: 2026.03.18 STMICROELECTRONICS INT NV

Figure 1A~1B
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AI summary

Apparatuses, systems, and methods for locating tag positions using a single-chip are provided. An exemplary method includes enabling a first antenna of a near-field communication (NFC) reader and disabling a second antenna of the NFC reader; obtaining a first signal via the first antenna based at least in part on enabling the first antenna and disabling the second antenna; after obtaining the first signal, enabling the second antenna and disabling the first antenna; obtaining a second signal via the second antenna based at least in part on enabling the second antenna and disabling the first antenna; and determining a respective location of a first NFC device and a second NFC device based at least in part on the first signal being indicative of a first identifier associated with the first NFC device and the second signal being indicative of a second identifier associated with the second NFC device.