RFID Transponder Power Control for Reliable Memory Writes

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Solution Overview

Problem

Ultra-low power RFID transponders, such as those used in HF and UHF tags, face challenges in maintaining power during write operations due to high current consumption and limited sampling frequency resolution, leading to potential system resets under low power conditions.

Innovation Solution

The implementation of a power detector and current control module within the RFID transponder continuously monitors available power, generating a power-dependent control signal to adjust current consumption through a charge pump, allowing for balanced memory operations and preventing power depletion by controlling write operations based on available energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If discrete-time sampling is used to monitor power and control write speed, then power consumption is reduced, but measurement precision and response accuracy deteriorate

Engineering Contradiction:
Improvepower consumptionVSAvoidpower monitoring accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent implements continuous monitoring of the power indicator signal throughout the write operation, rather than using discrete-time sampling. This continuous observation allows the system to detect power level changes in real-time and respond immediately, maintaining both low power consumption and high measurement precision by only controlling current consumption when actually needed.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent employs a feedback mechanism where the continuously monitored power indicator signal is fed back to the control logic, which then adjusts the current consumption accordingly. This closed-loop feedback system ensures that power monitoring accuracy is maintained while avoiding unnecessary continuous high-power operation, thus resolving the contradiction between power consumption and measurement precision.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If sampling frequency is increased to improve power monitoring accuracy, then measurement precision improves, but power consumption increases

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

Solution Approach 1:

Instead of increasing sampling frequency, the patent uses continuous monitoring of the power indicator signal. This approach provides uninterrupted visibility into power levels without the overhead of frequent discrete sampling cycles, achieving high measurement precision while maintaining ultra-low power consumption throughout the operation.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system monitors its own power indicator signal continuously and autonomously adjusts its current consumption based on real-time power availability. This self-service mechanism eliminates the need for external high-frequency sampling control, allowing the transponder to maintain accurate power monitoring while consuming minimal power through intelligent, event-driven current control.

Inventive Principle:
Principle #25Self-service

3Productivity

If write operation proceeds at full speed, then productivity increases, but reliability decreases under low power conditions

Engineering Contradiction:
Improvewrite speedVSAvoidsystem stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent dynamically adjusts the write operation speed based on the continuously monitored power indicator signal. When sufficient power is available, the write operation proceeds at full speed for high productivity. When power levels drop below thresholds, the system automatically slows down or pauses the write operation to maintain reliability, preventing system resets and ensuring successful completion of memory operations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the write operation in response to power conditions. By monitoring the power indicator signal and adjusting write speed and current consumption parameters dynamically, the system optimizes the balance between productivity and reliability, ensuring that write operations succeed even under varying power availability without requiring fixed high-speed operation.

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 ensures reliable and accurate memory operations in ultra-low power RFID transponders by optimizing current consumption in response to varying power levels, preventing resets and maintaining system functionality even under low power conditions.

Implementation Method 1

an antenna for receiving and transmitting signals

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The radio frequency energy received by the transponder's antenna is rectified and filtered into a DC voltage

Methodology Applied
Scientific EffectRectification: Diode

Data Source

PatentEP3862924B1Agile time-continuous memory operation for a radio frequency identification transponder
Publication Date: 2023.05.24 NXP BV
  • EP3862924B1 patent drawingFigure 1
  • EP3862924B1 patent drawingFigure 2
  • EP3862924B1 patent drawingFigure 3

AI summary

A radio frequency identification (RFID) transponder includes a current control module for controlling a current consumption of a memory based on an amount of available power, and a control logic for controlling a memory operation in response to the control of the current consumption by the current control module. The RFID transponder further includes a power detector that is configured to continuously monitor and detect the amount of available power and output a power-dependent control signal. The power-dependent control signal is used by the RFID transponder to control the current consumption of the memory in dependence on the available power.