Wireless Charger Filtering Circuit for AM Radio Interference
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Solution Overview
Problem
Wireless-charger transmitters face increased interference when components are removed to reduce cost and complexity, particularly in frequency bands corresponding to AM radio.
Innovation Solution
An integrated circuit with a wireless-charger transmitter that includes a driver circuit and a selectively coupled filtering circuit, which filters out interference signals in the AM radio frequency band based on the switching frequency of the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If components are removed from the wireless-charger transmitter to reduce cost and complexity, then manufacturing cost and device complexity are reduced, but interference in the AM radio frequency band increases
Solution Approach 1:
The patent extracts the filtering function as a separate, selectively-coupled circuit component. This allows the filtering capability to be removed from the main transmitter circuitry when not needed, reducing baseline complexity and cost, while being available to suppress interference when the transmitter operates in frequency ranges that affect AM radio bands.
Solution Approach 2:
The filtering circuit is dynamically coupled to the transmitter based on operating conditions. The circuit transitions between connected and disconnected states depending on the transmitter's switching frequency, allowing the system to adapt its interference suppression capability to match actual operational needs, thus balancing complexity and interference reduction.
2Object-generated harmful factors
If a filtering circuit is added to reduce interference, then interference in the AM radio frequency band is reduced, but device complexity and cost increase
Solution Approach 1:
The filtering circuit incorporates switching mechanisms that dynamically connect or disconnect the filter based on the transmitter's operating frequency. This dynamic behavior ensures the filter is only active when interference is likely, reducing the effective component count during normal operation while maintaining interference suppression when needed.
Solution Approach 2:
The filtering function is applied locally and selectively to specific frequency ranges rather than being a permanent, broad-spectrum component. This localized approach allows interference suppression to be implemented only in the problematic AM radio frequency band, minimizing the impact on overall system complexity.
3Object-generated harmful factors
If the filtering circuit is always connected to the wireless-charger transmitter, then interference is consistently filtered, but charging power is reduced due to continuous power loss across the filter
Solution Approach 1:
The filtering circuit operates periodically rather than continuously, being activated only during specific operating conditions (certain switching frequency ranges) where interference is generated. This periodic operation eliminates unnecessary power losses during conditions where filtering is not required, while still providing interference suppression when needed.
Solution Approach 2:
The circuit dynamically adjusts its state based on real-time operating conditions, connecting the filter only when the transmitter operates in frequency ranges that generate AM radio interference. This dynamic control prevents continuous power loss through the filter while ensuring interference is suppressed when the transmitter's switching frequency creates harmful emissions.
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
The solution reduces interference while maintaining a reduced component count and complexity, allowing the wireless-charger transmitter to be used in various systems and devices without significant charging power loss.
Implementation Method 1
the wireless-charger transmitter selectively filters out an interference signal in a band of frequencies corresponding to AM radio
Implementation Method 2
a switched wireless-charger transmitter may generate interference in a band of frequencies corresponding to amplitude modulated (AM) radio
Data Source
AI summary
An integrated circuit is described. This integrated circuit may include wireless-charger transmitter. The wireless-charger transmitter includes a driver circuit. Moreover, the wireless-charger transmitter selectively filters out an interference signal in a band of frequencies corresponding to AM radio. Note that the selective filtering may be performed by at least a filtering circuit. For example, the filtering circuit may include a low-pass filter. Moreover, the selective filtering using the filtering circuit may be based at least in part on a switching frequency of the wireless-charger transmitter. Furthermore, a filtering frequency associated with the filtering circuit (such as a 3 dB cutoff frequency of a low-pass filter) may be adjusted by selectively electrically coupling a set of capacitors in parallel with the filtering circuit.