Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback

This paper presents a mathematical analysis of a fully differential BD-modulated Class-D amplifier with analog feedback, i.e., one having a bridge-tied-load output configuration with negative feedback and ternary PWM signal. Notwithstanding the highly nonlinear nature of the amplifier's operat...

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Main Authors: Cox, Stephen M., Yu, J., Goh, W.L., Tan, M.T.
Format: Article
Published: IEEE 2013
Online Access:https://eprints.nottingham.ac.uk/1886/
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author Cox, Stephen M.
Yu, J.
Goh, W.L.
Tan, M.T.
author_facet Cox, Stephen M.
Yu, J.
Goh, W.L.
Tan, M.T.
author_sort Cox, Stephen M.
building Nottingham Research Data Repository
collection Online Access
description This paper presents a mathematical analysis of a fully differential BD-modulated Class-D amplifier with analog feedback, i.e., one having a bridge-tied-load output configuration with negative feedback and ternary PWM signal. Notwithstanding the highly nonlinear nature of the amplifier's operation, an extremely accurate closed-form expression for the audible output signal is derived and verified based on computer simulations. This expression demonstrates that there exist larger high-order intrinsic distortions (e.g., 5th-order harmonic distortion and intermodulation distortion) for BD-modulation, compared to that for AD-modulation (binary PWM signal). Furthermore, the 3rd-order harmonic distortion has a roughly parabolic response as a function of the magnitude of the input signal and reaches its peak when the modulation index of the input signal is around 0.7. Overall, the BD-modulated Class-D amplifier has a larger intrinsic distortion for small input signal but a smaller intrinsic distortion for large input signal, compared to AD-modulated designs.
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spelling nottingham-18862020-05-04T20:19:58Z https://eprints.nottingham.ac.uk/1886/ Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback Cox, Stephen M. Yu, J. Goh, W.L. Tan, M.T. This paper presents a mathematical analysis of a fully differential BD-modulated Class-D amplifier with analog feedback, i.e., one having a bridge-tied-load output configuration with negative feedback and ternary PWM signal. Notwithstanding the highly nonlinear nature of the amplifier's operation, an extremely accurate closed-form expression for the audible output signal is derived and verified based on computer simulations. This expression demonstrates that there exist larger high-order intrinsic distortions (e.g., 5th-order harmonic distortion and intermodulation distortion) for BD-modulation, compared to that for AD-modulation (binary PWM signal). Furthermore, the 3rd-order harmonic distortion has a roughly parabolic response as a function of the magnitude of the input signal and reaches its peak when the modulation index of the input signal is around 0.7. Overall, the BD-modulated Class-D amplifier has a larger intrinsic distortion for small input signal but a smaller intrinsic distortion for large input signal, compared to AD-modulated designs. IEEE 2013 Article PeerReviewed Cox, Stephen M., Yu, J., Goh, W.L. and Tan, M.T. (2013) Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback. IEEE Transactions on Circuits and Systems I: Regular Papers, 60 (1). pp. 63-73. ISSN 1549-8328 http://dx.doi.org/10.1109/TCSI.2012.2215713 doi:10.1109/TCSI.2012.2215713 doi:10.1109/TCSI.2012.2215713
spellingShingle Cox, Stephen M.
Yu, J.
Goh, W.L.
Tan, M.T.
Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title_full Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title_fullStr Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title_full_unstemmed Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title_short Intrinsic distortion of a fully differential BD-modulated Class-D amplifier with analog feedback
title_sort intrinsic distortion of a fully differential bd-modulated class-d amplifier with analog feedback
url https://eprints.nottingham.ac.uk/1886/
https://eprints.nottingham.ac.uk/1886/
https://eprints.nottingham.ac.uk/1886/