RFID Persistent Node Circuit for Temperature-Stable State Storage
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Solution Overview
Problem
Existing RFID tags face variability in state storage time due to temperature and processing variations, leading to inconsistent performance and increased costs in maintaining calibration or trimming to reduce these variations.
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 predictable and stable persistent node operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FET-based state storage devices are used, then the tag can maintain state storage functionality, but the state storage time varies significantly with temperature and processing variations
Solution Approach 1:
The patent changes the fundamental parameter used for state storage from FET leakage current to capacitor discharge through a thin oxide layer. This parameter change makes the discharge time independent of temperature and processing variations, as the thin oxide layer discharge characteristics remain stable across different operating conditions.
Solution Approach 2:
The patent uses a thin oxide layer (10-50 nanometers) that can be easily formed through standard semiconductor processing. This thin oxide layer acts as a disposable, temperature-insensitive discharge path that replaces the need for precise FET leakage control, simplifying the overall device design and improving reliability.
2Device complexity
If FET leakage current is used to control capacitor discharge, then the circuit can be simple, but the discharge time is unknown and widely varying due to parasitic effects
Solution Approach 1:
The patent extracts the discharge control function from the FET leakage mechanism and places it in a dedicated thin oxide layer. This separation allows the FET to simply charge the capacitor while the thin oxide layer independently controls the discharge time, eliminating the coupling between charging and discharging mechanisms and providing predictable discharge characteristics.
Solution Approach 2:
The patent substitutes the FET leakage current mechanism (which is sensitive to parasitic effects and processing variations) with a capacitor discharge through a thin oxide layer. This substitution provides a more stable and predictable discharge time that is less affected by manufacturing variations and operating conditions.
3Reliability
If trimming or calibration is applied to reduce variations, then the discharge time can be more consistent, but the manufacturing cost increases significantly
Solution Approach 1:
The patent makes the thin oxide layer discharge mechanism inherently self-regulating and insensitive to temperature and processing variations. The discharge time is determined by the capacitor voltage and the thin oxide layer characteristics, which naturally provide consistent discharge behavior without requiring external trimming or calibration circuits, thereby reducing manufacturing cost.
Solution Approach 2:
The patent uses a thin oxide layer that can be easily formed through standard semiconductor processing as a disposable, temperature-insensitive discharge path. This approach replaces expensive trimming or calibration circuits with a simple, robust structure that provides consistent discharge time without additional manufacturing steps or components.
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 provides a high-performing, cost-effective persistent node that maintains timing accuracy and state storage over a wide temperature range without the need for expensive trimming or calibration, ensuring consistent RFID tag performance.
Implementation Method 1
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
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.