Reduction of spectral distortion in class D amplifiers by an enhanced pulse width modulation sampling process

Mellor, P.H.; Leigh, Simon; Cheetham, B.M.G.

doi:10.1049/ip-g-2.1991.0076

Cited by 41 publications

(24 citation statements)

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“…(Significant effort has also been applied to devising remedies for the effects of imperfections in the circuit components [2], for example, nonlinearities in a carrier waveform that is generally modelled mathematically as a piecewise-linear (triangular or sawtooth) wave [6].) Unfortunately, the simplest design is prone to noise (including thermal and outputstage power-supply noise), due to a lack of negative feedback, and so more sophisticated versions of the class-D design have been developed, incorporating such feedback, in an attempt to counter the poor noise performance.…”

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confidence: 99%

Class-D Audio Amplifiers with Negative Feedback

Cox¹,

Candy²

2005

SIAM J. Appl. Math.

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Abstract. There are many different designs for audio amplifiers. Class-D, or switching, amplifiers generate their output signal in the form of a high-frequency square wave of variable duty cycle (ratio of on time to off time). The square-wave nature of the output allows a particularly efficient output stage, with minimal losses. The output is ultimately filtered to remove components of the spectrum above the audio range. Mathematical models are derived here for a variety of related class-D amplifier designs that use negative feedback. These models use an asymptotic expansion in powers of a small parameter related to the ratio of typical audio frequencies to the switching frequency to develop a power series for the output component in the audio spectrum. These models confirm that there is a form of distortion intrinsic to such amplifier designs. The models also explain why two approaches used commercially succeed in largely eliminating this distortion; a new means of overcoming the intrinsic distortion is revealed by the analysis.

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confidence: 99%

Class-D Audio Amplifiers with Negative Feedback

Cox¹,

Candy²

2005

SIAM J. Appl. Math.

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“…One is PWM signal generated by natural sampling method which is called as natural sampling PWM signal (NPWM), another is PWM signal produced by uniform sampling method known as uniform sampling PWM signal (UPWM).For triangular carrier signal,it has two forms which the first is sawtooth signal known as "single sided" signal because only a single edge of the PWM waveform is modulated .Another is triangular ISSN: 2250-3021 www.iosrjen.org 932 | P a g e signal called "double sided" signal [6,7]. For the proposed method NPWM signal will be introduced.…”

Section: Principle Of Operationmentioning

confidence: 99%

Design and Analysis of Pulse width Modulator (PWM) using Low Input Impedance Current Comparator

Choudhary¹

2012

IOSRJEN

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In this paper a new design of a simple pulse width modulator is presented. The proposed scheme has 3mW average power consumption which is less than the existing PWM methods. This circuit is also suitable for IC implementation. The simulation results are carried out under the implementation of TSMC 0.35μm CMOS process with 1.8V power supply. This method is commonly used for driving motors, heaters, or lights in varying intensities or speeds. The simulation and experimental results are shown in this paper. It is also suitable for high power applications as well as ordinary low power use, while possessing important advantages. Pulse-width (PW) modulation has been widely used to convert analog (or multibit digital) signals to binary streams.

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“…Digital signals are sampled in nature, and its PW modulation is termed in the literature as regular [5] or uniformly (U-) [6]- [8] sampled PW (U-PW) modulation. The U-PW-modulated signal spectrum contains in the signal band the spectral components of the N-PW-modulated signal as well as some harmonics of the input signal [9].…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis of Pulsewidth-Modulated Sampled Signals

Colodro

Torralba

2010

IEEE Trans. Circuits Syst. II

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Pulsewidth (PW) modulation has been widely used to convert analog (or multibit digital) signals to binary streams. It is well known that PW modulation of a sampled signal produces harmonic distortion. This effect is analyzed, and new expressions are obtained for the Fourier transform of the modulated output, which are valid for any input signal. In addition, simple expressions are given to compute the harmonic distortion factors for a sinusoidal input signal. It is also shown that a three-level PW modulation can reduce the distortion factors down to a level appropriate for most signal-processing applications. Finally, these analytical results are validated by simulation for two data converters based on sigma-delta modulation, where the sampled output of a multibit quantizer is PW modulated: one digital-to-analog and one analog-to-digital converter, respectively.

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Reduction of spectral distortion in class D amplifiers by an enhanced pulse width modulation sampling process

Cited by 41 publications

References 3 publications

Class-D Audio Amplifiers with Negative Feedback

Class-D Audio Amplifiers with Negative Feedback

Design and Analysis of Pulse width Modulator (PWM) using Low Input Impedance Current Comparator

Spectral Analysis of Pulsewidth-Modulated Sampled Signals

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