Audio Output Offset Compensation for Pop Noise Suppression
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Solution Overview
Problem
Audio devices often produce pop noise due to DC offset and voltage changes during power on/off or plug insertion/removal, which is annoying and difficult to mitigate with existing technologies.
Innovation Solution
An audio device comprising an adder, digital-to-analog conversion circuit, amplifying circuit, voltage detecting circuit, and offset compensation circuit that uses a linear equation to calculate and apply a DC offset compensation value based on the supply voltage, thereby eliminating the DC offset and preventing pop noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If DC offset compensation is not implemented, then the audio device structure remains simple, but pop noise occurs during power on/off and plug insertion/removal
Solution Approach 1:
The offset compensation circuit calculates and applies a compensation value before the audio signal is processed, based on the detected supply voltage. This preliminary compensation prevents DC offset from causing pop noise during power transitions or plug insertion/removal, resolving the contradiction by adding a proactive correction mechanism rather than reacting to the noise after it occurs.
Solution Approach 2:
The patent introduces an offset compensation circuit as an intermediary component between the power supply and the audio signal processing chain. This mediator detects supply voltage changes and generates compensation values that counteract DC offset effects, thereby preventing pop noise without fundamentally altering the core audio processing functionality.
2Reliability
If voltage detection and compensation circuits are added, then pop noise is prevented, but the device complexity increases
Solution Approach 1:
The offset compensation circuit is integrated into the existing audio processing pipeline, sharing resources with other circuit components. The voltage detection function is combined with the existing power management infrastructure, and the compensation is applied through the existing digital signal processing path, thereby reducing the need for entirely separate dedicated circuits.
Solution Approach 2:
The offset compensation circuit automatically detects supply voltage changes and generates appropriate compensation values without external intervention. The system self-regulates by continuously monitoring its own power supply conditions and adjusting the compensation accordingly, eliminating the need for manual calibration or external control mechanisms.
3Measurement precision
If real-time voltage detection is implemented, then DC offset compensation accuracy is improved, but processing time and energy consumption increase
Solution Approach 1:
Instead of continuous real-time voltage detection, the system performs voltage detection and compensation updates at periodic intervals or at specific trigger events (such as power on/off transitions or plug insertion/removal). This periodic approach maintains adequate compensation accuracy while significantly reducing the energy consumption associated with continuous monitoring and processing.
Data Source
AI summary
An audio device is adapted to receive and process a digital audio signal and output an analog audio signal. The audio device includes an adder, a digital-to-analog conversion circuit, an amplifying circuit, a voltage detecting circuit and an offset compensating circuit. The voltage detecting circuit detects a supply voltage received by the amplifying circuit. The offset compensating circuit generates a DC offset compensation value according to the supply voltage. The adder adds the digital audio signal and the DC offset compensation value to output an added signal. The digital-to-analog conversion circuit converts the added signal into a converted analog audio signal. The amplifying circuit amplifies the converted analog signal to output an amplified analog signal. Accordingly, the audio device can reduce pop noise caused by a DC offset.