Audio Signal Offset Clipping for Low-Distortion Class C Amplifiers
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Solution Overview
Problem
Class C amplifiers are not typically used for audio amplification due to high distortion levels, and existing solutions to reduce distortion either lead to increased power consumption or unacceptable audio quality.
Innovation Solution
An audio processor that modifies a digital audio signal by adding a time-varying offset and clipping the signal to remove negative values, allowing a class C amplifier to be used with reduced distortion and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a class C amplifier is used, then power consumption is reduced, but distortion increases
Solution Approach 1:
The audio processor performs preliminary signal conditioning before the amplifier stage by adding an offset to shift the audio signal into the positive voltage range and applying soft clipping to limit negative excursions. This preliminary action prepares the signal so that the class C amplifier operates in its linear region, reducing distortion while maintaining power efficiency.
Solution Approach 2:
The audio processor acts as an intermediary between the digital audio signal and the class C amplifier. It processes the signal by adding an offset and applying soft clipping, transforming the signal into a form suitable for class C amplification, thereby mediating between the conflicting requirements of low power consumption and low distortion.
2Manufacturing precision
If a class A amplifier is used, then distortion is reduced, but power consumption increases
Solution Approach 1:
The audio processor performs preliminary signal conditioning by adding an offset to shift the audio signal into the positive voltage range and applying soft clipping to limit negative excursions. This preliminary action prepares the signal so that the class C amplifier operates in its linear region, reducing distortion while maintaining power efficiency.
Solution Approach 2:
The invention changes the operating parameters of the amplifier by using a class C configuration with biased operation rather than traditional class A. By adjusting the bias point and signal conditioning parameters, the system achieves low distortion performance similar to class A but with the power efficiency of class C operation.
3Use of energy by moving object
If PWM modulation is used, then power efficiency is improved, but signal fidelity may deteriorate
Solution Approach 1:
The audio processor performs preliminary signal conditioning by adding an offset and applying soft clipping before the PWM modulation stage. This ensures that the input signal to the PWM amplifier is properly conditioned, preventing distortion and maintaining signal fidelity while preserving the power efficiency benefits of PWM operation.
Solution Approach 2:
The audio processor acts as an intermediary between the digital audio signal and the PWM amplifier, conditioning the signal through offset addition and soft clipping. This mediation ensures that the PWM modulation receives a properly prepared signal, maintaining signal fidelity while preserving power efficiency.
Data Source
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AI summary
An audio processor and method of audio processing for an amplifier system is described. The audio processor may receive an audio signal and adapt the audio signal generating a time varying offset. The time varying offset may be combined with the audio signal resulting in a shifted the audio signal level. The processed audio signal may also be clipped to remove the negative samples values. The processed signal may be used to drive an amplifier designed to only accept positive (or negative) signals such as a class C amplifier.