Wireless Charger ASK Demodulation With Timed Sample-and-Hold
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Solution Overview
Problem
Current wireless charging systems face challenges with bulky hardware designs and low demodulation accuracy for amplitude-shift keying (ASK) modulation due to in-band noise, necessitating a compact and efficient demodulation solution.
Innovation Solution
The implementation of a power transmitter with a timing control circuit that generates synchronized control signals to alternately turn ON and OFF switches at a specific frequency, coupled with sample-and-hold circuits to sample current and voltage at precise instants, effectively demodulating ASK signals while rejecting switching frequency noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If current hardware design for ASK demodulation is used, then demodulation function is achieved, but hardware becomes bulky
Solution Approach 1:
The patent replaces traditional bulky hardware demodulation circuits with a digital signal processing approach using a microcontroller unit (MCU). The ASK demodulation is achieved through software-based envelope detection and signal processing algorithms, eliminating the need for complex analog demodulation hardware while maintaining high demodulation accuracy even in the presence of in-band noise.
2Reliability
If ASK demodulation is implemented for in-band communication, then communication capability is enabled, but demodulation accuracy decreases due to in-band noise
Solution Approach 1:
The patent employs digital signal processing techniques that can distinguish between useful ASK modulated signals and in-band noise through spectral analysis and envelope detection algorithms. The system selectively processes frequency components corresponding to the ASK modulation while filtering out noise, effectively converting the noisy environment into a manageable condition for accurate demodulation.
Solution Approach 2:
The patent introduces an intermediary digital signal processing stage between the received ASK signal and the final demodulated output. This intermediary processing includes envelope detection, rectification, and filtering operations that isolate the modulated signal from in-band noise, enabling accurate demodulation despite the presence of noise in the wireless power transfer band.
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 enables compact, high-accuracy ASK demodulation in wireless charging systems, improving noise immunity and reducing demodulation errors, thus enhancing the efficiency and reliability of in-band communication.
Implementation Method 1
Wireless charging is sometimes known as inductive charging, which uses an electromagnetic field to transfer power between a power transmitter and a power receiver. The power is sent through inductive coupling to an electrical device
Implementation Method 2
The second induction coil converts the power back into electric current, which is then used to charge a battery or directly drive electrical devices
Data Source
AI summary
A power transmitter includes: a first switch coupled between a first node and a reference voltage node; a second switch configured to be coupled between a power supply and the first node; a coil and a capacitor coupled in series between the first node and the reference voltage node; a first sample-and-hold (S&H) circuit having an input coupled to the first node; and a timing control circuit configured to generate a first control signal, a second control signal, and a third control signal that have a same frequency, where the first control signal is configured to turn ON and OFF the first switch alternately, the second control signal is configured to turn ON and OFF the second switch alternately, and where the third control signal determines a sampling time of the first S&H circuit and has a first pre-determined delay from a first edge of the first control signal.