Headphone Ground Feedback Circuit for Audio Crosstalk Reduction
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Solution Overview
Problem
Existing audio processing technologies in smartphones and mobile devices cause excessive crosstalk between audio channels due to high resistance in the common ground current return path, leading to poor HiFi audio quality and an unacceptable listening experience, especially when using USB Type-C interfaces and 3.5 mm headphone jacks.
Innovation Solution
An audio processing apparatus with a control switch and audio processing chip that includes a first and second power amplifier, where the control switch feeds back a reference feedback signal to the common negative terminal and connects the headphone ground signal with the main board ground, reducing the resistance path and minimizing crosstalk by using a path resistor instead of a load resistor for current return, thereby improving the crosstalk index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a USB Type-C interface is used to replace the 3.5 mm headphone jack and multiplex audio functionality, then the device can achieve thinner design and interface integration, but the crosstalk level significantly deteriorates due to high resistance in the common ground current return path
Solution Approach 1:
The patent segments the common ground current return path into two parts: the original high-resistance path through the audio processing apparatus, and a new low-resistance path through a dedicated resistor connected between the common negative terminal and main board ground. This segmentation allows the harmful high-resistance path to be bypassed while maintaining the necessary electrical connections for audio functionality.
Solution Approach 2:
The patent introduces a dedicated resistor as an intermediary element to provide a new current return path. This resistor serves as a mediator that offers lower resistance compared to the original common ground path, thereby reducing crosstalk while still allowing the common negative terminal to function properly in the USB Type-C audio interface.
2Adaptability or versatility
If a self-adaptive switching circuit is integrated on the main board to support compatibility between OMTP and CTIA standards, then the device achieves broader headphone compatibility, but the crosstalk index is reduced
Solution Approach 1:
The patent segments the ground reference path by providing a separate, dedicated low-resistance path for the common negative terminal through a dedicated resistor. This segmentation isolates the switching circuit's ground currents from the audio signal return path, preventing crosstalk while maintaining the switching functionality needed for OMTP and CTIA compatibility.
Solution Approach 2:
The dedicated resistor acts as an intermediary that provides a stable, low-resistance ground reference for the common negative terminal, independent of the switching circuit's ground path. This intermediary element ensures that the switching operations for headphone compatibility do not introduce crosstalk into the audio signal path.
3Object-affected harmful factors
If the common negative terminal is directly connected to main board ground through a low-resistance path, then the crosstalk level is reduced, but the stability of the common ground reference may be affected
Solution Approach 1:
The patent changes the resistance parameter of the common ground reference path by introducing a dedicated resistor with optimized resistance value. This resistor provides lower resistance than the original common ground path (reducing crosstalk) while still providing sufficient isolation and stability (maintaining reference integrity). The resistance value is carefully selected to balance these two competing requirements.
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 significantly reduces crosstalk by an order of magnitude, improving the HiFi audio quality and allowing users to better position musical instruments in music, achieving a crosstalk level below -65 dB, which is the industry standard for HiFi audio.
Implementation Method 1
the control switch is coupled with a common negative terminal of the first power amplifier and the second power amplifier, and is configured to feed back a reference feedback signal to the common negative terminal, and connect a headphone ground signal of the audio output interface with a main board ground; the reference feedback signal is obtained by performing voltage sampling on the headphone ground signal
Data Source
AI summary
Embodiments of the present disclosure provide an audio processing apparatus, and an audio crosstalk processing method and apparatus. The audio processing apparatus includes: an audio processing chip, a control switch and an audio output interface. The audio processing chip includes a first power amplifier and a second power amplifier; wherein the first power amplifier is configured to output a left channel signal; the second power amplifier is configured to output a right channel signal; and the control switch is coupled with a common negative terminal of the first power amplifier and the second power amplifier, and is configured to feed back a reference feedback signal to the common negative terminal, and connect a headphone ground signal of the audio output interface with a main board ground, the reference feedback signal is obtained by performing voltage sampling on the headphone ground signal.