Ear Jack Common Port Switching for Audio Cross-Talk Reduction
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Solution Overview
Problem
Cross-talk between left and right audio channels in mobile terminals with earphone antennas occurs due to the use of inductors with DC resistance, which affects stereo performance and FM radio reception sensitivity.
Innovation Solution
A switching unit is introduced to connect the EAR_COM port directly to GND or the FM signal tuner based on the on/off state of the FM radio reception function, allowing for reduced cross-talk by controlling the connection of the common port for reference potential and radio signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inductor is used to connect EAR_COM to GND via the FM radio antenna port, then FM radio reception sensitivity is improved, but cross-talk between left and right audio channels is generated
Solution Approach 1:
The patent implements a dynamic switching mechanism that changes the connection state of EAR_COM based on the FM radio reception state. When FM reception is active, EAR_COM connects to the radio signal tuner; when inactive, it connects directly to GND. This dynamic reconfiguration resolves the contradiction by adapting the circuit topology to operational requirements, eliminating cross-talk during audio playback while maintaining FM reception capability.
Solution Approach 2:
The switching unit acts as an intermediary component that mediates between EAR_COM and the two possible destinations (GND and radio signal tuner). This intermediary element enables selective connection based on operational mode, allowing the system to achieve both low cross-talk (via GND connection) and good FM reception (via tuner connection) at different times without compromising either function.
2Object-generated harmful factors
If an inductor with low DC resistance is used to connect EAR_COM to GND, then cross-talk is reduced, but FM radio reception sensitivity deteriorates
Solution Approach 1:
Instead of using a fixed inductor with compromised DC resistance, the patent employs a dynamic switching mechanism that connects EAR_COM directly to GND when FM reception is not active. This eliminates the need for a low-DC-resistance inductor during audio playback, thereby reducing cross-talk without sacrificing FM reception sensitivity when needed.
Solution Approach 2:
The switching unit serves as an intermediary that replaces the inductor's dual-function role. By providing a direct GND connection path when FM reception is inactive, the switching unit achieves the low cross-talk performance that would otherwise require a low-DC-resistance inductor, while preserving the high-sensitivity FM reception capability when the switch connects to the tuner.
3Object-generated harmful factors
If EAR_COM is directly connected to GND, then cross-talk is reduced, but the ability to receive FM radio signals through the earphone port is lost
Solution Approach 1:
The patent implements a dynamic connection system where EAR_COM's connection target changes based on operational mode. During audio playback, EAR_COM connects directly to GND to minimize cross-talk. During FM reception, the switch reconfigures to connect EAR_COM to the radio signal tuner, enabling FM signal reception through the earphone port. This dynamic adaptability resolves the contradiction between cross-talk reduction and FM reception capability.
Solution Approach 2:
The switching unit provides multi-functionality by enabling EAR_COM to serve different purposes in different operational modes: audio ground reference during music playback and FM signal input during radio reception. This universal design allows the same hardware component to support both audio playback with low cross-talk and FM radio reception without compromising either function.
Data Source
AI summary
An apparatus and a method for reducing cross-talk between audio channels in a mobile terminal are provided. The apparatus includes an ear jack, a radio signal tuner, a baseband, and a switching unit. The ear jack includes a common port for a reference potential of an earphone and a radio signal. The radio signal tuner processes a radio signal input via the common port. The baseband determines an on/off state of a radio reception function to output a control signal. The switching unit connects the common port of the ear jack to one of a ground and the radio signal tuner according to the control signal.