Configurable Limiter for ASK and OOK Modulation Protocols

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Solution Overview

Problem

Multiprotocol NFC tags face issues with voltage induction due to suboptimal limiter behavior when switching between ASK and OOK modulation protocols, leading to variations in Frame Delay Time, which are not within the specified tolerance range.

Innovation Solution

A configurable limiter is implemented in NFC tags that can switch between configurations optimized for ASK and OOK modulation protocols, ensuring accurate detection of rising edges and minimizing Frame Delay Time variations by maintaining impedance consistency during signal reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the limiter is switched off for OOK modulation to preserve signal amplitude, then the signal amplitude is maintained, but the rising edge detection threshold must be raised which causes late detection and large Frame Delay Time variations

Engineering Contradiction:

Improvesignal amplitude preservationVSAvoidFrame Delay Time variation

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The limiter is made dynamically configurable with two distinct configurations: a first configuration for ASK modulation that limits voltage amplitude, and a second configuration for OOK modulation that preserves signal amplitude. The system dynamically switches between these configurations based on the detected modulation type, allowing optimal performance for each protocol without compromise.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The limiter's operational parameters are changed based on the detected protocol. For OOK modulation, the limiter configuration parameters are adjusted to preserve signal amplitude while still providing protection, enabling early rising edge detection without excessive threshold raising that would cause Frame Delay Time variations.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If the threshold is put relatively low to detect rising edges early, then Frame Delay Time variation is reduced, but the limiter behavior must be changed from ASK-optimized to OOK-optimized configuration

Engineering Contradiction:

ImproveFrame Delay Time variationVSAvoidlimiter configuration management

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The system uses feedback from protocol detection to automatically adjust the limiter configuration. When OOK modulation is detected, the system feedbacks this information to the limiter control, which then switches to the appropriate configuration, eliminating the need for manual intervention and reducing Frame Delay Time variations automatically.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The limiter is designed with multi-functionality to handle both ASK and OOK modulation protocols effectively. By incorporating two configurations within a single limiter device, the system achieves universal compatibility across different NFC protocols without requiring separate limiter circuits for each protocol type.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a single limiter configuration optimized for ASK modulation is used, then ASK protocol performance is maximized, but OOK protocol detection suffers from late rising edge detection and large Frame Delay Time variations

Engineering Contradiction:

ImproveASK protocol performanceVSAvoidOOK rising edge detection precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The limiter functionality is segmented into distinct configurations for different modulation types. Instead of using a single monolithic limiter design, the system divides the limiter operation into separate optimized modes: one for ASK modulation and another for OOK modulation, allowing each to perform at its optimal level without interfering with the other.

Inventive Principle:

Principle #1Segmentation

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 allows for precise detection of modulated pulses across different protocols, reducing Frame Delay Time variations and ensuring compliance with tight tolerance ranges by adapting limiter behavior based on detected protocols.

Implementation Method 1

NFC uses electromagnetic induction between two loop antennas located within each other's near field, effectively forming an air-core transformer

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3584949B1Method for limiting the level of a modulated signal received by a tag and corresponding limiter

Publication Date: 2022.01.19 STMICROELECTRONICS RAZVOJ POLPREVODNIKOV D O O

Figure 1~2
Figure 3A
Figure 3B

AI summary

1. An integrated circuit having an input configured to receive an induced signal (SIG), said induced signal (SIG) being modulated according to a protocol belonging to the group including protocols using ASK modulation and protocols using OOK modulation, said integrated circuit comprising: - detection means (DET) configured to detect said modulation; - decoding means (DEC) configured to detect said protocol. - a configurable limiter (LIM) configured to limit the level of the induced signal and having a first configuration (MODE1) adapted to protocols using ASK modulation and a second configuration (MODE2) adapted to protocols using OOK modulation; - control means (CM) configured to set the limiter in said first configuration (MODE1) until protocol is detected, and configured to switch the limiter from said first configuration (MODE1) to said second configuration (MODE2) if a protocol using OOK modulation is detected.