RFID Tag Backscatter Level Adjustment via Dynamic Impedance Control
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Solution Overview
Problem
Passive RFID tags experience a decrease in backscatter level due to non-linearity in response to increasing input RF power, which affects detection efficiency and signal-to-noise ratio.
Innovation Solution
Adjusting the input impedance of the RFID tag based on monitored input power levels by selecting and bypassing rectifier stages, using control signals to optimize impedance for improved backscatter performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the input RF power is increased to improve detection range, then the detection range is extended, but the backscatter level decreases due to non-linearity
Solution Approach 1:
The patent applies dynamics by making the rectifier circuit configuration changeable based on operating conditions. The controller dynamically switches between different rectifier configurations (first and second configurations) depending on the detected RF power level, allowing the system to adapt to varying power conditions and maintain optimal backscatter performance across different detection ranges.
Solution Approach 2:
The patent changes the operational parameters of the rectifier circuit by switching between different configurations. When RF power exceeds a threshold, the system transitions from a first rectifier configuration to a second configuration, altering the circuit's electrical characteristics to compensate for non-linearity effects and maintain stable backscatter level despite increasing input power.
2Use of energy by moving object
If the rectifier circuit is configured to maximize power conversion, then power efficiency is improved, but the backscatter level becomes unstable at high RF power
Solution Approach 1:
The system dynamically adjusts the rectifier circuit configuration based on real-time RF power detection. At lower power levels, the first configuration maximizes power conversion efficiency. When RF power exceeds a predetermined threshold, the controller switches to the second configuration that prioritizes backscatter level stability, thus adapting the circuit behavior to current operating conditions.
Solution Approach 2:
The patent implements feedback by continuously monitoring the RF power level and using this information to control the rectifier configuration switching. The controller receives feedback about the operating conditions and adjusts the rectifier circuit accordingly, creating a closed-loop system that maintains optimal performance across varying power levels.
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
Compensates for the decrease in backscatter level associated with increasing RF power, enhancing detection efficiency and signal-to-noise ratio, and improving Received Signal Strength Indicator (RSSI) detection.
Implementation Method 1
A passive tag is a beam powered device which rectifies energy required for operation from radio waves generated by a reader
Implementation Method 2
For communication, the passive tag creates a change in reflectivity of the field which is reflected to and read by the reader. This is commonly referred to as backscattering.
Implementation Method 3
The transmitter and receiver can be combined as a transceiver which can use one or more antennas
Data Source
AI summary
An input power on a tag is monitored. An input impedance of the tag is adjusted based on the monitored input power to increase a backscatter level of the tag. In one embodiment, an output voltage of a rectifier device is monitored. An input power to the tag is determined based on the output voltage. An input impedance of the tag is adjusted based on the input power to increase the backscatter level of the tag.