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Towards a Low Cost, Microcontroller-Based Class-D Audio Amplifier

Authors:
Erik Genthe
Timm Bostelmann
Sergei Sawitzki

Keywords: Measurement; Class-D; Microcontroller.

Abstract:
In this implementation study, a simple, low cost digital (class-D) audio amplifier is presented. Class-D audio amplifiers are much more efficient than prior (analogue) types of amplifiers. However, such amplifiers still have significant power losses due to quiescent currents independent of their output power. The design goal was to reduce the complexity of the hardware design as much as possible while keeping high audio quality and power efficiency. This is done by covering as much complexity as possible with a standard microcontroller using its internal hardware Pulse-Width Modulation (PWM) for signal generation. A key part of this work lies in the measurement and evaluation of the implemented amplifier prototype. It is shown that the Total Harmonic Distortion Plus Noise (THD+N) is less than 1 % for frequencies up to 500 Hz. Further analysis shows that quantization is the main source of this noise. At 10 kHz, the measured THD+N is 7.0 %, which is audible. However, this high noise level is not caused by quantization. The prototype has a quiescent current of 159 mA. The prototype demonstrates the potential of this simple approach in terms of energy efficiency. In addition, significant improvements could be achieved by incorporating noise shaping algorithms and multi-level switching techniques.

Pages: 1 to 6

Copyright: Copyright (c) IARIA, 2024

Publication date: November 3, 2024

Published in: conference

ISSN: 2308-426X

ISBN: 978-1-68558-201-2

Location: Nice, France

Dates: from November 3, 2024 to November 7, 2024