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Digital control of a class-D audio amplifier
Author(s)
Quibell, Jason
Date Issued
2011
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Modern technologies have led to extensive digital music reproduction and distribution.
It is fitting then that digital audio be amplified directly from its
source rather than being converted to an analogue waveform before amplification.
The benefits of using a digital controller for audio processing include
being able to easily reconfigure the system and to add additional functions at
a later stage.
Digital audio is primarily stored as Pulse Code Modulation (PCM) while
Pulse Width Modulation (PWM) is the most popular scheme used to drive
a class-D amplifier. The class-D amplifier is selected in many applications
due to its very high energy efficiency. Conventional PCM to PWM conversion
is inherently nonlinear. Various interpolation schemes are presented in this
research project which help to address the nonlinearity.
Digitally generated PWM has a limited resolution which is constrained
by the system clock. This thesis presents noise shaping techniques which
increase the effective resolution of the PWM process without having to use an
excessively high system clock. Noise shaping allows a low resolution modulator
to be used to reproduce high resolution audio.
It is fitting then that digital audio be amplified directly from its
source rather than being converted to an analogue waveform before amplification.
The benefits of using a digital controller for audio processing include
being able to easily reconfigure the system and to add additional functions at
a later stage.
Digital audio is primarily stored as Pulse Code Modulation (PCM) while
Pulse Width Modulation (PWM) is the most popular scheme used to drive
a class-D amplifier. The class-D amplifier is selected in many applications
due to its very high energy efficiency. Conventional PCM to PWM conversion
is inherently nonlinear. Various interpolation schemes are presented in this
research project which help to address the nonlinearity.
Digitally generated PWM has a limited resolution which is constrained
by the system clock. This thesis presents noise shaping techniques which
increase the effective resolution of the PWM process without having to use an
excessively high system clock. Noise shaping allows a low resolution modulator
to be used to reproduce high resolution audio.
Additional information
Thesis (MTech (Electrical Engineering)--Cape Peninsula University of Technology, 2011
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Quibell_J_MTech_Digital Control of a Class-D Audio Amplifier.pdf
Description
Thesis
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8.36 MB
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Adobe PDF
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