Transponder Rectifier Circuit Voltage Limiting

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Solution Overview

Problem

High magnetic field intensities from NFC readers can degrade the integrated circuit of transponders, particularly when in card mode, due to excessive voltage levels.

Innovation Solution

A method and device that utilize a rectifier circuit with cross-coupled transistors and a control circuit to modify the input impedance of the transponder's integrated circuit, reducing the voltage by dissipating excessive energy through controlled gate voltage management, thereby limiting the voltage at the antenna and integrated circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the reader generates a high magnetic field to improve communication range and signal strength, then the communication performance is improved, but the voltage at the transponder's integrated circuit increases causing damage

Engineering Contradiction:

Improvemagnetic field intensityVSAvoidvoltage degradation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary circuit between the antenna and the integrated circuit that captures excessive voltage energy and redirects it to a dummy load, protecting the integrated circuit from high magnetic field intensities while maintaining communication functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful excessive voltage energy into useful heat energy by directing it to a dummy load, thereby protecting the integrated circuit while utilizing the excess energy rather than letting it cause damage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Use of energy by moving object

If the transponder operates in passive mode to reduce power consumption, then energy efficiency is improved, but the ability to actively control voltage limiting is reduced

Engineering Contradiction:

Improvepower consumptionVSAvoidvoltage control capability

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent implements a self-service mechanism where the transponder automatically detects excessive voltage conditions and activates the voltage limiting circuit without external control, enabling passive mode operation while maintaining protective capabilities

Inventive Principle:

Principle #25Self-service

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

Effectively reduces the voltage at the antenna and integrated circuit, preventing damage from high magnetic field intensities and enabling safer communication in NFC applications.

Implementation Method 1

the reader generates a magnetic field by using its antenna... The force of the magnetic field is, for example, between 0.5 and 7.5 Amperes/RMS (Root Mean Square) meter

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a rectifier circuit comprising two transistors cross-coupled between the terminals of the antenna and a reference voltage

Methodology Applied

Scientific EffectRectification:

Data Source

PatentUS11593577B2Method for limiting the voltage, level received from a magnetic field by a transponder and corresponding transponder

Publication Date: 2023.02.28 STMICROELECTRONICS FRANCE

AI summary

A method for limiting voltage at an input of an integrated circuit of a transponder contactlessly communicating with a reader includes, during the contactless communication: receiving a carrier signal at an antenna of the transponder; and controlling gate voltages of two transistors of a rectifier circuit of the transponder so as to modify an input impedance of the integrated circuit, wherein the two transistors are cross-coupled between terminals of the antenna and a reference voltage.