NFC Circuit Resonant Frequency Control for Leakage Current Protection
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Solution Overview
Problem
Existing NFC circuits face issues with leakage current damage to NFC card circuits when the NFC reader circuit is enabled and reduced communication efficiency due to shared resonant frequencies for data transmission and reception, leading to impedance reduction and inefficient coupling.
Innovation Solution
The NFC circuit incorporates a resonance and matching circuit, an NFC card circuit with a load modulation circuit that controls resistance values in response to control signals, allowing for selective adjustment of resonant frequencies and disconnecting the NFC card circuit during data transmission to prevent leakage current, while connecting it during data reception to enhance communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the NFC reader circuit is enabled to communicate with the outside, then communication functionality is improved, but leakage current damages the NFC card circuit
Solution Approach 1:
The patent applies preliminary action by configuring the NFC card circuit to be in a high-impedance state before the NFC reader circuit operates. The control unit预先 sets the NFC card circuit to disconnect from the antenna, preventing leakage current from reaching it when the reader circuit is enabled for communication.
Solution Approach 2:
The patent introduces an intermediary control unit that manages the switching between NFC reader and NFC card modes. This control unit acts as a mediator that coordinates the operation of both circuits, ensuring the NFC card circuit is properly isolated when the reader circuit is active, thus preventing harmful leakage current while maintaining communication functionality.
2Device complexity
If the same resonant frequency is used for both data transmission and reception, then circuit simplicity is maintained, but impedance reduction lowers communication efficiency
Solution Approach 1:
The patent applies dynamics by making the resonant frequency adjustable rather than fixed. The control unit dynamically changes the resonant frequency of the antenna based on the operational mode: using a first resonant frequency for data transmission and a second resonant frequency for data reception. This dynamic adjustment optimizes communication efficiency while maintaining relatively simple circuit architecture.
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 effectively protects the NFC card circuit from leakage current and improves communication efficiency by allowing distinct resonant frequencies for data transmission and reception, thereby enhancing overall NFC circuit performance.
Implementation Method 1
a resonance and matching circuit coupled between the NFC reader circuit and nodes of the antenna
Implementation Method 2
The NFC card circuit controls a resonant frequency of the antenna in response to the plurality of control signals
Implementation Method 3
a load modulation circuit configured to control a resistance value in response to the plurality control signals when the NFC reader circuit is enabled
Data Source
AI summary
The near field communication (NFC) circuit includes an NFC reader circuit configured to communicate with an outside through an antenna, a resonant and matching circuit connected between the NFC reader circuit and the antenna, an NFC card circuit connected to nodes and configured to communicate with the outside through the antenna, and a processor configured to output a plurality of control signals when the NFC reader circuit is enabled, wherein the NFC card circuit is configured to control a resonant frequency of the antenna in response to the plurality of control signals.