RF Smart Card Capacitor Switching for Stable Power Demodulation
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Solution Overview
Problem
Smart cards face issues with power stability and signal distortion during communication, which affect their reliability and security in biometric authentication processes.
Innovation Solution
The smart card incorporates a RF module with a rectification signal line, a regulator, a power circuit, a logic circuit, and a capacitor circuit that dynamically adjust capacitance based on communication enable signals to extract power and signal components from RF signals, ensuring stable power and reduced signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed capacitor circuit is used in the RF module, then the circuit structure is simple, but power stability deteriorates and signal distortion increases during communication
Solution Approach 1:
The capacitor circuit transitions from a fixed structure to a dynamic one by enabling capacitance adjustment based on operational mode. The controller switches between a first capacitance value during power extraction and a second capacitance value during signal demodulation, allowing the circuit to adapt to different operational requirements and resolve the contradiction between structural simplicity and power stability.
2Device complexity
If a fixed capacitor circuit is used in the RF module, then the circuit structure is simple, but signal distortion increases during communication
Solution Approach 1:
The capacitor circuit is made dynamic by adjusting capacitance values according to operational mode. During signal demodulation, the capacitance is set to a second value that minimizes signal distortion, while during power extraction, a first capacitance value is used. This dynamic adjustment resolves the contradiction between structural simplicity and signal quality.
3Reliability
If capacitance is adjusted dynamically based on operational mode, then power stability is improved, but device complexity increases
Solution Approach 1:
The capacitor circuit is designed to serve multiple functions by adjusting its capacitance value based on operational mode. The same capacitor circuit handles both power extraction (first capacitance value) and signal demodulation (second capacitance value), making the circuit multi-functional and reducing the need for separate dedicated circuits for each function.
4Reliability
If capacitance is adjusted dynamically based on operational mode, then signal distortion is reduced, but device complexity increases
Solution Approach 1:
The capacitor circuit is designed as a multi-functional component that adjusts its capacitance value to optimize performance for different operations. The same circuit structure performs both power extraction and signal demodulation with appropriate capacitance adjustments, reducing the need for separate dedicated circuits and minimizing overall device complexity.
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 configuration enhances power stability and reduces signal distortion, improving the reliability and security of biometric authentication in smart card transactions.
Implementation Method 1
a rectifier configured to extract a rectification signal from a radio frequency (RF) signal
Implementation Method 2
a capacitor circuit configured to receive the rectification signal, wherein the capacitor circuit has a first capacitance while the signal component is extracted from the rectification signal and has a second capacitance different from the first capacitance while the signal component is not extracted from the rectification signal
Data Source
AI summary
A smart card with improved power stability is provided. The smart card comprises a rectification signal line through which a rectification signal extracted from a radio frequency (RF) signal is provided; a regulator configured to regulate a voltage of the rectification signal line to a first voltage; a power circuit configured to extract a power component from the rectification signal using an output of the regulator; a logic circuit configured to receive the power component and generate a reception enable signal on the basis of the power component; a demodulator which is enabled by the reception enable signal provided from the logic circuit and configured to extract a signal component from the rectification signal; a capacitor controller which is enabled by the reception enable signal provided from the logic circuit and configured to generate a capacitor enable signal; and a capacitor circuit which is connected to the rectification signal line and has capacitance changed according to the capacitor enable signal.