Mobile Audio Multiplexing Circuit With Discrete Switch Paths
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Solution Overview
Problem
The high cost of integrated switches in mobile terminals due to their complex structure, which increases product costs and impairs compatibility with external devices.
Innovation Solution
A multiplexing circuit comprising three switch circuits, each configured to handle different voltage levels for audio signal transmission and data charging, allowing for efficient switching between headset and data cable interfaces, utilizing transistors and constant voltage control circuits to reduce impedance changes and improve THD-N indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an integrated switch is used to switch circuits coupled to an interface in a mobile phone, then switching functionality between headset and data cable modes is achieved, but the complex structure increases product costs
Solution Approach 1:
The patent divides the integrated switch into multiple independent discrete transistors (first transistor for right audio channel, second transistor for left audio channel, third transistor for data transmission). Each transistor is controlled by separate control signals, allowing independent switching of different circuit paths. This segmentation simplifies the overall structure by replacing a complex integrated switch with basic discrete components while maintaining the required switching functionality.
Solution Approach 2:
The discrete transistor-based switch circuit achieves multi-functionality by handling both audio transmission (headset mode) and data transmission (data cable mode) through the same circuit infrastructure. The first and second transistors handle audio signals for left and right channels respectively, while the third transistor handles data transmission, all through a unified switching mechanism that adapts to different connection types.
2Adaptability or versatility
If an integrated switch is used to provide compatibility with external devices, then multi-interface support is achieved, but product costs increase
Solution Approach 1:
The patent replaces expensive integrated switches with inexpensive discrete transistors and control circuits. The discrete components are cheaper to manufacture and assemble, even though they require more individual parts. The control circuits generate switching signals to enable the transistors to perform the functions previously handled by costly integrated switches, achieving the same compatibility functionality at lower cost.
3Ease of manufacture
If discrete transistors are used instead of integrated switches, then product cost is reduced, but impedance changes and THD-N indices may worsen
Solution Approach 1:
The patent introduces control circuits that generate switching control signals based on the operational state of the audio interface. These control circuits monitor the circuit state and adjust the switching signals accordingly to maintain optimal performance. The feedback mechanism ensures that the discrete transistor switching maintains stable impedance characteristics and low THD-N indices by dynamically adjusting switching timing and duration based on real-time circuit conditions.
Solution Approach 2:
The patent optimizes the switching parameters of the discrete transistors to minimize impedance changes during switching operations. By carefully controlling the gate voltage timing and duration of transistor conduction, the circuit maintains consistent impedance characteristics across different switching states. The control circuits adjust switching parameters dynamically to ensure audio signal quality remains high, keeping THD-N indices low while using cost-effective discrete components.
Data Source
AI summary
A multiplexing circuit and a mobile terminal, related to the field of electronic and communications technologies, that resolve a problem that product costs are high when a mobile phone uses an integrated switch. In the multiplexing circuit, a first switch circuit transmits, to a first signal transmission end, a right sound channel audio signal provided by a right sound channel transmission end. A second switch circuit transmits, to a second signal transmission end, a left sound channel audio signal provided by a left sound channel transmission end. Signal transmission between the first signal transmission end and a first output end and signal transmission between the second signal transmission end and a second output end are implemented by using a third switch circuit. The first switch circuit includes a first transistor and a first constant voltage control circuit.