Audio Playback Path Switching for Artifact-Free Class-AB/Class-D Modes
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Solution Overview
Problem
Existing audio amplifiers, such as class-D amplifiers, face challenges in efficiently switching between Class-AB and Class-D output stages, leading to audio artifacts due to mode switching, especially when amplifying low-magnitude signals and requiring large dynamic range.
Innovation Solution
A system with a control circuit that selectively switches between Class-AB and Class-D output stages based on input signal characteristics, using a preconditioning circuit to minimize artifacts by maintaining a stable impedance and calibrating gains and offsets, and employing a feedback network to control the amplifier's operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a class-D amplifier is used to improve power efficiency, then power dissipation is reduced, but audio artifacts are generated when switching between operational modes
Solution Approach 1:
The patent applies preliminary action by pre-conditioning the output signal before mode switching occurs. A preconditioning circuit prepares the signal in advance to ensure smooth transition between Class-AB and Class-D modes, preventing audio artifacts from being generated during the switching process.
Solution Approach 2:
The patent introduces an intermediary preconditioning circuit that acts as a mediator between the input signal and the output stage. This circuit conditions the signal to maintain stability during mode transitions, eliminating the direct harmful effect of switching between amplifier modes.
2Use of energy by moving object
If a configurable output stage is implemented to switch between Class-AB and Class-D modes, then power efficiency is improved, but audio artifacts are caused by the switching process
Solution Approach 1:
The control circuit performs preliminary actions by monitoring signal characteristics and pre-conditioning the output before mode switching. This ensures that transitions between Class-AB and Class-D modes occur smoothly without generating audible artifacts, while still achieving power efficiency benefits.
Solution Approach 2:
The patent changes operational parameters dynamically by switching between Class-AB and Class-D modes based on signal characteristics. The preconditioning circuit adjusts signal parameters in advance to ensure smooth transitions, maintaining both power efficiency and audio quality.
3Use of energy by moving object
If mode switching is performed based on signal characteristics, then power efficiency is improved, but signal quality may be affected by switching artifacts
Solution Approach 1:
The preconditioning circuit performs preliminary signal conditioning based on detected signal characteristics before mode switching occurs. This ensures that power efficiency is optimized through appropriate mode selection while signal quality is maintained by preventing switching artifacts.
Solution Approach 2:
The control circuit uses feedback from signal characteristic detection to determine when mode switching should occur. This feedback mechanism ensures that switching decisions are based on actual signal conditions, optimizing power efficiency while maintaining signal quality through artifact-free transitions.
Data Source
AI summary
In accordance with embodiments of the present disclosure, a system may include a playback path and a control circuit. The playback path may have a playback input for receiving an input signal and configured to generate at a playback path output an output signal based on the input signal, wherein the playback path is configured to operate in a plurality of operational modes. The control circuit may be configured to receive a first signal from within the playback path and indicative of the input signal, receive a second signal generated from the input signal externally to the playback path, and select a selected operational mode from the plurality of operational modes based on the first signal and the second signal.