Universal Audio Jack Switching With Slew-Controlled Pop Suppression
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Solution Overview
Problem
Audio interface circuits in devices like laptops and smartphones generate undesirable audible artifacts such as pops and clicks due to mismatched configurations, potentially damaging audio output equipment.
Innovation Solution
Implementing an audio interface circuit with a first audio circuit operating in a low voltage domain and a second circuit in a high voltage domain, coupled by a switching circuit with slew-rate control to manage transitions and prevent artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switching circuit is used to couple the high voltage domain circuit to the audio terminal, then the circuit can provide both line output and microphone bias functions, but audible artifacts such as pops and clicks are generated during switching transitions
Solution Approach 1:
The slew rate control circuit pre-regulates the voltage transition rate before the switching circuit connects the high voltage domain circuit to the audio terminal. By controlling the slew rate of the output voltage from the second circuit, the transition is made gradual rather than abrupt, preventing the generation of pops and clicks during configuration changes or device connections.
2Speed
If voltage transitions are made quickly for rapid configuration changes, then device responsiveness is improved, but audible artifacts and potential damage to audio equipment increase
Solution Approach 1:
The patent changes the parameter of voltage transition rate by introducing slew rate control. The slew rate control circuit dynamically adjusts the rate of voltage change during switching transitions, ensuring that voltage changes occur within safe limits that prevent damage to audio equipment while still enabling configuration changes to occur in real-time.
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 effectively reduces or eliminates audible artifacts, protecting audio equipment and ensuring smooth signal transitions.
Implementation Method 1
The second circuit has an output that is slew-rate controlled to control a transition time of the output of the second circuit in response to the control signal
Data Source
AI summary
Circuit techniques reduce or prevent audible artifacts in a Universal Audio Jack (UAJ) interface circuit, improving handling of mis-configuration/mis-attachment of devices. The interface includes at least one terminal for accepting an audio input signal or providing an audio line output signal coupled to an input or output of a first audio circuit. The first audio circuit operates from a low voltage domain and receives the audio input signal or provides the audio line output signal. A second circuit operates from a higher voltage domain and a switching circuit couples the at least one terminal to the second circuit. The output is slew-rate controlled to control a transition time of the output, so that audible artifacts in the audio input signal or the audio line output signal that could be generated by the switching circuit connecting the second circuit to the at least one terminal are avoided.