RFID Persistent Node Timing Using Tunneling Current Storage
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Solution Overview
Problem
Existing RFID tags with state storage devices face variations in discharge time due to semiconductor fabrication process variations and temperature changes, leading to inconsistent performance and increased costs for calibration or trimming.
Innovation Solution
A state storage device using a tunneling device with a thin silicon dioxide layer and a differential sensing circuit, where the discharge time is controlled by the tunneling current, independent of ambient temperature, and a switch with negligible leakage current, allowing for accurate and cost-effective persistent node operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a FET is used to charge/discharge a capacitor for state storage, then the state storage device can maintain power during reader off periods, but the discharge time varies significantly due to parasitic leakage current and temperature changes
Solution Approach 1:
The patent changes the discharge mechanism from FET leakage current to tunneling current through a thin oxide layer. By adjusting the oxide thickness parameter (controlling tunneling current), the discharge time becomes predictable and consistent across temperature variations and manufacturing processes, resolving the reliability issue while maintaining duration.
2Reliability
If calibration or trimming is applied to reduce FET current variation, then discharge time consistency improves, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces the expensive calibrated FET approach with a disposable thin oxide layer that provides consistent tunneling current without requiring calibration or trimming. The thin oxide can be manufactured using standard semiconductor processes, eliminating additional fabrication steps and reducing manufacturing cost while maintaining discharge time consistency.
3Adaptability or versatility
If the reader hops between transmission frequencies, then communication flexibility improves, but the tag loses power during frequency transitions causing timing circuit failures
Solution Approach 1:
The patent uses the thin oxide capacitor to preliminarily store energy and maintain power during anticipated frequency hopping transitions. The capacitor is charged in advance and discharges during reader off periods, ensuring the timing circuit remains operational throughout frequency changes without interrupting communication flexibility.
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
The solution provides a persistent node with stable performance over temperature and fabrication process variations, maintaining accurate timing without additional calibration or trimming, thus enhancing the reliability and efficiency of RFID tags.
Implementation Method 1
A state storage device can include a tunneling device with a thin silicon dioxide layer and a differential sensing circuit, where the discharge time is controlled by the tunneling current
Data Source
AI summary
An RFID transponder in one embodiment comprises a radio frequency (RF) transceiver, processing logic coupled to the RF transceiver, a switch coupled to the processing logic, a tunneling device coupled to the switch and a differential sensing circuit having a first input coupled to the tunneling device and a second input coupled to a predetermined reference voltage. In one embodiment, the tunneling device can discharge to a voltage below the predetermined reference voltage.