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Title: A micropower low-distortion digital class-D amplifier based on an algorithmic pulsewidth modulator
Authors: Gwee, Bah Hwee
Chang, Joseph Sylvester
Victor, Adrian
Keywords: DRNTU::Engineering::Electrical and electronic engineering
Issue Date: 2005
Source: Gwee, B. H., Chang, J. S., & Victor, A. (2005). A micropower low-distortion digital class-D amplifier based on an algorithmic pulsewidth modulator. IEEE Transactions on Circuits and Systems-I: Regular Papers, 52(10).
Series/Report no.: IEEE transactions on circuits and systems-I : regular papers
Abstract: A digital Class-D amplifier comprises a pulsewidth modulator (PWM) and an output stage. In this paper, we simplify the time-domain expression for the algorithmic PWM linear interpolation (LI) sampling process and analytically derive its double Fourier series expression. By means of our derivation, we showthat the nonlinearities of the LI process are very low, especially given its modest computation complexity and low sampling frequency. In particular, the total-harmonic distortion (THD) 0 02%and foldback distortion is 98.4 dB (averaged from modulation indexes = 0.1 to 0.9) for the 4-kHz voiceband bandwidth @1-kHz input, 48-kHz sampling.We also describe a simple hardware for realizing the LI process.We propose a frequency doubler (with small overheads) for the pulse generator for the PWM, thereby reducing the counter clock rate by 2, leading to a substantial 47% power dissipation reduction for the Class-D amplifier. By means of computer simulations and on the basis of experimental measurements, we verify our double Fourier series derivation and show the attractive attributes of a Class-D amplifier embodying our simplified LI sampling expression and reduced clock rate pulse generator. We show that our Class-D amplifier design is micropower ( 60 W@1.1 V and 48-kHz sampling rate, and THD 0.03%) and is suitable for practical power-critical portable audio devices, including digital hearing aids.
ISSN: 1057-7122
DOI: 10.1109/TCSI.2005.852920
Rights: © 2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EEE Journal Articles

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