Active RFID Tag Integrated Frequency Reference Clock Recovery

Solution Overview

Problem

Active RFID tags require external frequency references, which increase manufacturing costs and complexity, and introduce potential failure points, while also limiting the ability to operate on multiple communication protocols without separate components.

Innovation Solution

Incorporating an internal integrated frequency reference within the RFID chip that recovers a clock signal from received radio frequency signals, allowing the active RFID tag to generate a reference clock for transmitting data, eliminating the need for external frequency references and enabling operation across various communication protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external frequency references are used in active RFID tags, then frequency stability is improved, but manufacturing cost and device complexity increase

Engineering Contradiction:

Improvefrequency stabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the frequency reference functionality with the RFID chip itself by integrating a phase-locked loop (PLL) circuit and voltage-controlled oscillator (VCO) within the chip. This merging eliminates the need for separate external frequency reference components while maintaining frequency stability for both RFID and WiFi communications.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated frequency reference circuit is designed to serve multiple communication protocols simultaneously. The same PLL and VCO generate frequency references for both RFID interrogation signals and WiFi transmission, making the frequency reference system universal and eliminating the need for protocol-specific external references.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If external frequency references are used in active RFID tags, then frequency stability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefrequency stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the frequency reference functionality with the RFID chip itself by integrating a phase-locked loop (PLL) circuit and voltage-controlled oscillator (VCO) within the chip. This merging eliminates the need for separate external frequency reference components while maintaining frequency stability for both RFID and WiFi communications.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If separate frequency references are used for different communication protocols, then protocol-specific frequency accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvefrequency accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The integrated frequency reference circuit is designed to serve multiple communication protocols simultaneously. The same PLL and VCO generate frequency references for both RFID interrogation signals and WiFi transmission, making the frequency reference system universal and eliminating the need for protocol-specific external references.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses a voltage-controlled oscillator (VCO) that can adjust its output frequency based on control voltage. This allows the same hardware circuit to generate different frequency references for different protocols by changing the control parameters, maintaining frequency accuracy without requiring separate physical references for each protocol.

Inventive Principle:

Principle #35Parameter changes

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 reduces the cost and complexity of active RFID tags, enhances reliability, and allows for flexible operation across different frequency bands and communication protocols, such as NFC, WiFi, and Bluetooth, by using a single semiconductor chip with integrated frequency recovery capabilities.

Implementation Method 1

The RFID tag receives power when excited by a nearby electromagnetic field emitted the resonant frequency of the RFID tag

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an integrated frequency reference that recovers clocking from the radio frequency signal

Methodology Applied

Scientific EffectClock recovery:

Data Source

PatentUS11580316B2Interacting RFID tags

Publication Date: 2023.02.14 AVERY DENNISON RETAIL INFORMATION SERVICES LLC

AI summary

An active radio frequency identification (“RFID”) tag receives an RFID interrogation signal via a first antenna. An integrated frequency reference in the RFID chip recovers the clock from the RFID interrogation and generates a reference clock for transmitting data responsive to the RFID interrogation. The integrated frequency reference generates the reference clock at the same frequency as the RFID interrogation for transmitting the response via the first antenna. The integrated frequency reference generates the reference clock at a different frequency for transmitting the response using a Bluetooth beacon message or a WiFi message via a second antenna. A mobile computing device can interrogate the RFID tag via an NFC interface and receive a response via a Bluetooth beacon messages or WiFi message received via a Bluetooth or wireless interface of the mobile computing device.