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  • Research Article
  • Open Access
  • Distortion-Free 1-Bit PWM Coding for Digital Audio Signals

    EURASIP Journal on Advances in Signal Processing20072007:094386

    • Received: 15 June 2006
    • Accepted: 13 March 2007
    • Published:


    Although uniformly sampled pulse width modulation (UPWM) represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM). Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed "jither" and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., ) resulting to typical PWM clock rates of 90 MHz.


    • Pulse Width
    • Quantum Information
    • Generation Mechanism
    • Audio Signal
    • Pulse Width Modulation

    Authors’ Affiliations

    Department of Computer Science, Ionian University, Plateia Tsirigoti 7, Corfu, 49 100, Greece
    Audio Technology Group, Department of Electrical and Computer Engineering, University of Patras, Rio Patras, 265 00, Greece


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    © A. Floros and J. Mourjopoulos. 2007

    This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.