NFC Transmitter Driver Variable Resistance Clock Synchronization
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Solution Overview
Problem
Existing near field communication (NFC) devices face challenges in maintaining proper clock synchronization at high active load modulation strengths, due to limitations in the synchronization window caused by signal damping issues.
Innovation Solution
The NFC device incorporates a controller that dynamically changes the variable resistance of the transmitter driver and the HF attenuator during the modulation phase, allowing for improved signal damping and widening the synchronization window even at high active load modulation strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the NFC device uses conventional fixed resistance values in the transmitter driver and HF attenuator, then the device structure is simple, but clock synchronization fails at high active load modulation strengths due to insufficient signal damping
Solution Approach 1:
The patent applies dynamics by making the resistance values of the transmitter driver and HF attenuator variable rather than fixed. The controller dynamically adjusts these resistance values based on the modulation phase and active load modulation strength, enabling the system to adapt to changing conditions and maintain proper clock synchronization at high modulation strengths.
Solution Approach 2:
The patent changes the resistance parameter of the transmitter driver and HF attenuator based on operating conditions. By selecting different resistance values from predefined sets during different modulation phases and at different modulation strengths, the system optimizes signal damping to ensure reliable clock synchronization while managing device complexity through structured parameter selection.
2Reliability
If the NFC device increases signal damping to improve clock synchronization at high modulation strengths, then synchronization reliability improves, but the synchronization window becomes narrower
Solution Approach 1:
The system dynamically adjusts the balance between signal damping and synchronization window width by varying resistance values based on modulation phase and strength. During high modulation strength phases, increased damping improves synchronization reliability, while during other phases, the system maintains adequate window width through optimized resistance selection.
Solution Approach 2:
The controller implements periodic adjustment of resistance values synchronized with the modulation cycle. By coordinating resistance changes with the periodic modulation phases, the system maintains optimal signal damping during high modulation strength periods while preserving synchronization window width during lower modulation periods.
3Ease of manufacture
If the NFC device uses a single fixed resistance value for the transmitter driver, then the device is simpler to manufacture, but it cannot maintain proper signal damping across different modulation phases
Solution Approach 1:
The patent segments the resistance control into discrete selectable values organized in predefined sets corresponding to different modulation phases and active load modulation strengths. This segmentation allows the system to maintain proper signal damping across different phases while keeping the physical implementation simple through a finite set of resistor values rather than continuous adjustment mechanisms.
Data Source
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AI summary
In accordance with a first aspect of the present disclosure, a near field communication (NFC) device is provided, comprising: a modulator configured to modulate a carrier signal received from an external reader, resulting in a modulated carrier signal; a controller configured to control a transmission of the modulated carrier signal to the external reader; a transmitter driver configured to transmit said modulated carrier signal, said transmitter driver having a variable resistance; wherein the controller is further configured to change said variable resistance during a modulation phase of the NFC device such that a clock synchronization window is widened. In accordance with a second aspect of the present disclosure, a corresponding method of operating an NFC device is conceived. In accordance with a third aspect of the present disclosure, a non-transitory machine-readable medium is provided, comprising instructions which, when executed, carry out a method of the kind set forth.