Digital Audio Offset Compensation for Click-and-Pop Suppression
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Solution Overview
Problem
Digital audio devices suffer from audible artifacts like click-and-pop due to transient voltage offsets during operational mode transitions, and they also consume excessive power, which is detrimental for portable devices.
Innovation Solution
The solution involves adding a digital offset to the digitized audio signal based on the output offset introduced by analog components, which is then processed to cancel out the systematic DC offset, thereby reducing or eliminating click-and-pop and minimizing power consumption by eliminating DC leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the audio device operates with standard analog components, then the device structure remains simple, but output offset is introduced causing click-and-pop artifacts
Solution Approach 1:
The patent introduces a digital offset as an intermediary element that mediates between the digitized audio signal and the analog components. This digital offset compensates for the output offset introduced by analog components, preventing click-and-pop artifacts without requiring modification of the analog components themselves. The digital offset acts as a mediator that cancels the harmful effect at the digital level before conversion to analog.
Solution Approach 2:
The patent applies preliminary action by calculating and applying the digital offset before the audio signal passes through the analog components. The offset is determined based on the known characteristics of the analog components and is pre-applied to the digitized audio signal, so that when the signal undergoes digital-to-analog conversion and passes through the analog components, the output offset is already compensated.
2Object-generated harmful factors
If digital offset compensation is implemented, then click-and-pop artifacts are reduced, but device complexity increases
Solution Approach 1:
The patent implements self-service by having the system automatically calculate and apply the digital offset without requiring manual calibration or adjustment. The digital offset is determined based on the inherent characteristics of the analog components and is automatically applied to all audio signals, making the system self-correcting and reducing the need for external intervention or complex calibration procedures.
3Use of energy by moving object
If the audio device is in shutdown mode with power applied to amplifier, then power consumption is reduced, but output offset persists causing artifacts on signal resumption
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating the digital offset that will counteract the output offset present in shutdown mode. When the audio signal is resumed after shutdown, the pre-calculated digital offset is applied to cancel the persistent output offset, preventing click-and-pop artifacts. This allows the amplifier to remain in low-power shutdown mode while still eliminating artifacts upon signal resumption.
Data Source
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AI summary
A digital offset is combined with an audio signal in the digital domain to cancel an output offset caused by one or more analog components processing the same audio signal. In this manner, the offset at the output of the audio signal path (e.g., at a power amplifier output) is reduced or eliminated. Consequently, audible artifacts, such as click-and-pop artifacts, can be reduced or eliminated. In audio devices operating in ground-referenced capless mode, power consumption is reduced because of reduced or eliminated direct current (DC) leakage current through speakers or headsets of such audio devices. In some circumstances, the digital offset in the digital domain may be applied at substantially all times of operation of the audio signal path.