Synchronous Oscillator Phase Alignment for Active Load Modulation
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Solution Overview
Problem
Existing inductive coupling communication systems, such as NFC, face challenges in maintaining phase stability during active load modulation, requiring high precision and expensive circuitry to ensure bursts of magnetic field are in phase with the external magnetic field, which is costly and impractical for widespread implementation.
Innovation Solution
A method using a synchronous oscillator that resynchronizes with the external magnetic field before each burst of periodic signal application to the antenna circuit, incorporating attenuation, restoration, and resynchronization steps to maintain phase alignment without the need for extremely precise circuitry, allowing for reduced phase shift and improved communication stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase locked loop is used to control the phase of the load modulation magnetic field, then phase stability is improved, but device complexity and cost increase due to high precision requirements
Solution Approach 1:
The patent applies preliminary action by resynchronizing the oscillator with the external magnetic field before each burst of periodic signal application. This pre-synchronization ensures phase alignment is established in advance, eliminating the need for complex continuous phase locked loop circuitry while maintaining phase stability throughout the communication process.
2Length of stationary object
If continuous emission of magnetic field is used, then communication distance is extended, but power consumption increases significantly
Solution Approach 1:
The patent implements periodic action by applying bursts of periodic signals to the antenna circuit rather than continuous emission. The oscillator generates periodic bursts synchronized with the external magnetic field, maintaining communication effectiveness while significantly reducing power consumption compared to continuous operation.
3Reliability
If phase rotation occurs between load modulation magnetic field and external magnetic field, then communication distance fluctuates undesirably
Solution Approach 1:
The patent employs feedback by using the external magnetic field itself as a reference signal to resynchronize the oscillator before each burst. This feedback mechanism ensures the load modulation magnetic field remains phase-aligned with the external magnetic field, preventing phase rotations and maintaining stable communication distance without requiring high precision circuitry.
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 approach reduces the need for high-precision circuitry, enabling stable phase alignment and extended communication distance while minimizing power consumption, making it more cost-effective and practical for widespread use in NFC systems.
Implementation Method 1
receiving an antenna signal by way of an inductive antenna circuit in the presence of an alternating external magnetic field
Implementation Method 2
applying to the antenna circuit bursts of the second periodic signal to generate an active load modulation magnetic field
Data Source
AI summary
In a general aspect, a method can include producing, by an inductive antenna circuit, a first periodic signal that is based on an alternating external magnetic field; producing, by an oscillator circuit, a second periodic signal that is based on the first periodic signal; and transmitting, in correspondence with a data-carrying modulation signal, a sequence of data bits. The transmitting can include sequentially and repetitively: applying, with the oscillator circuit operating in a free oscillation mode, the second periodic signal to the inductive antenna circuit; and inhibiting, with the oscillator circuit operating in a synchronous oscillation mode, application of the second periodic signal to the inductive antenna circuit. The synchronous oscillation mode of the oscillator circuit can cause the second periodic signal to be synchronized to the first periodic signal.