Simplified NFC Circuit Design with Variable Capacitance
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Summary
Problems
Existing NFC communication circuits face challenges in adjusting resonant frequencies due to varying use conditions and limited antenna size, requiring complex circuit architectures with multiple capacitors and switches, which increases size and complexity.
Innovation solutions
A communication circuit that includes an RFIC, a control IC, and a variable capacitance element with a resistance voltage divider circuit, allowing for capacitance value adjustment without increasing the number of terminals, lines, or capacitance elements, thereby simplifying the circuit architecture and reducing size.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If multiple capacitors and switches are used to adjust resonant frequency, then frequency adjustment capability is improved, but circuit complexity and device size increase
Why choose this principle:
The patent uses a variable capacitance element whose capacitance value can be continuously adjusted by changing the control voltage applied to it. This allows the resonant frequency of the antenna circuit to be tuned without switching between discrete capacitor values, thereby reducing circuit complexity while maintaining frequency adjustment capability.
Principle concept:
If multiple capacitors and switches are used to adjust resonant frequency, then frequency adjustment capability is improved, but circuit complexity and device size increase
Why choose this principle:
The control voltage line serves multiple functions: it controls the RFIC operation and simultaneously adjusts the capacitance value of the variable capacitance element. This multi-functionality reduces the number of dedicated control lines needed, simplifying the overall circuit architecture.
Application Domain
Data Source
AI summary:
A communication circuit that includes an RFIC, a control IC, and a variable capacitance element with a resistance voltage divider circuit, allowing for capacitance value adjustment without increasing the number of terminals, lines, or capacitance elements, thereby simplifying the circuit architecture and reducing size.
Abstract
In a communication circuit, an RFIC includes an IO terminal and a control IC includes an IO terminal. A variable capacitance element includes control terminals, a capacitance element with a capacitance value that is determined according to a control voltage, and a resistance voltage divider circuit configured to generate the control voltage by dividing a voltage inputted to the control terminals. One of the RFIC and the control IC supplies control data to the variable capacitance element via a signal line. The variable capacitance element, along with an antenna coil, constitutes an antenna circuit of an LC parallel resonance circuit, and sets a resonant frequency of the antenna circuit to be a predetermined frequency.