Audio Gain-Mode Switching for Artifact-Free Dynamic Range Enhancement
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Solution Overview
Problem
Existing audio devices face challenges in maintaining a high dynamic range of audio signals while reducing noise and audio artifacts when switching between dynamic range enhancement modes, as increased gain often leads to signal noise that masks lower-intensity audio signals.
Innovation Solution
An apparatus and method that include a signal path with both analog and digital signal path portions, and a control circuit that switches between different gain modes by adjusting the product of the analog and digital gains to maintain a constant cumulative gain, reducing noise and artifacts through precise control of the signal path's response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high gain is applied to the power amplifier to increase dynamic range, then the dynamic range is improved, but signal noise increases which masks lower-intensity audio signals
Solution Approach 1:
The audio signal path is divided into two separate paths: a digital signal path portion that processes higher-level signals and an analog signal path portion that processes lower-level signals. This segmentation allows each path to operate with optimized gain levels, preventing the analog path from introducing excessive noise while maintaining overall dynamic range through digital processing.
Solution Approach 2:
A control circuit acts as an intermediary between the digital and analog signal path portions, dynamically switching between them based on the input signal level. This mediator ensures that the analog path is only activated when necessary for low-level signals, avoiding noise introduction during high-level signal processing while maintaining dynamic range enhancement capabilities.
2Stability of the object's composition
If the selectable digital gain is switched between two levels with transient response, then dynamic range enhancement is achieved, but audio artifacts become perceptible to listeners
Solution Approach 1:
The system performs preliminary actions by preparing both the digital and analog signal path portions in advance, with the control circuit anticipating signal level transitions. This allows smooth switching between paths before artifacts can become perceptible, maintaining dynamic range enhancement while eliminating audible glitches.
Solution Approach 2:
The control circuit ensures continuous useful action by maintaining seamless operation between digital and analog signal paths. The switching mechanism is designed to preserve signal continuity and prevent transient responses that would create perceptible audio artifacts, thereby maintaining both dynamic range enhancement and audio quality.
Data Source
AI summary
In accordance with embodiments of the present disclosure, a control circuit may be configured to, responsive to an indication to switch between gain modes of a signal path having an analog path portion and a digital signal path portion, switch a selectable analog gain of the analog path portion between a first analog gain and a second analog gain, switch a selectable digital gain of the digital signal path portion between a first digital gain and a second digital gain, wherein the product of the first analog gain and the first digital gain is approximately equal to the product of the second analog gain and the second digital gain, and control an analog response of the signal path to reduce the occurrence of audio artifacts present in the output signal as a result of the switch between gain modes of the signal path.A signal path may have an analog path portion and a digital signal path portion. The digital portion may have a selectable digitally-controlled gain and may be configured to convert a digital audio input signal into an analog input signal in conformity with the selectable digitally-controlled gain, the digital signal path portion comprising a modulator including a forward path and a feedback path. The forward path may include a loop filter for generating a filtered signal responsive to the digital audio input signal and a feedback signal, a quantizer responsive to the filtered signal for generating a quantized signal, and a first gain element configured to apply the selectable digitally-controlled gain to a signal within the forward path. The feedback path may be configured to generate the feedback signal responsive to the quantized signal, the feedback path including a second gain element having a gain inversely proportional to the selectable digitally-controlled gain.