Remote Powered Contactless Card With Variable-Capacitance Tuning
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Solution Overview
Problem
Current contactless card manufacturing methods cause significant inaccuracies in antenna capacitance and resonance frequency, leading to improper tuning with terminals and affecting data demodulation quality.
Innovation Solution
An electronic device with a variable-capacitance capacitive element adjusts its capacitance iteratively to maximize the instantaneous electric power received from an antenna, using a capacitive element with a digital-to-analog converter to fine-tune the resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current contactless card manufacturing methods are used, then production is simple and fast, but the capacitance of the antennas has significant inaccuracy leading to resonance frequency errors
Solution Approach 1:
The patent applies the dynamics principle by making the capacitance value adjustable and variable rather than fixed. The antenna circuit includes a capacitance adjustment mechanism that allows the capacitive element's value to be modified dynamically to compensate for manufacturing inaccuracies and achieve proper resonance tuning with the terminal.
Solution Approach 2:
The patent implements parameter changes by varying the capacitance value of the capacitive element in the antenna circuit. By changing this electrical parameter, the resonance frequency of the contactless card can be adjusted to match the terminal's operating frequency, thereby improving manufacturing precision without requiring extremely tight initial tolerances.
2Reliability
If the contactless card is not correctly tuned with the terminal, then manufacturing is easier, but data demodulation quality deteriorates
Solution Approach 1:
The patent applies self-service by implementing an automatic tuning mechanism that adjusts the capacitance value without requiring manual intervention. The system autonomously measures the resonance condition and modifies the capacitive element's value to achieve optimal tuning with the terminal, thereby ensuring reliable data demodulation while eliminating complex manual tuning operations.
Solution Approach 2:
The patent implements feedback by using a measurement circuit that monitors the resonance condition of the antenna-terminal system. Based on this feedback information, the capacitance adjustment mechanism modifies the capacitive element's value to maximize power transfer and ensure correct tuning, thereby improving data demodulation quality automatically.
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 ensures optimal resonance with the terminal, enhancing data demodulation performance by maximizing the amplitude of the received signal, thus improving the operating efficiency of the contactless card.
Implementation Method 1
The terminal emits a magnetic field which is captured by an antenna of the telepowered contactless card
Implementation Method 2
the resonance frequency of the assembly comprising the contactless card and the terminal is close or equal to the frequency of the field emitted by the terminal
Data Source
AI summary
In an embodiment an electronic device includes a first electronic circuit having a capacitive element with a variable capacitance, wherein the first electronic circuit is configured to couple the capacitive element to an antenna, to measure, by successive iterations, a first analog signal representative of a variation of an instantaneous electric power received by the antenna or representative of the instantaneous electric power received by the antenna and to modify the capacitance of the capacitive element until an amplitude of the instantaneous electric power received by the antenna is a maximum, wherein the antenna is configured to capture an amplitude-modulated electromagnetic field.