Book•
Understanding Delta-Sigma Data Converters
08 Nov 2004-
TL;DR: This chapter discusses the design and simulation of delta-sigma modulator systems, and some of the considerations for implementation considerations for [Delta][Sigma] ADCs.
Abstract: Chapter 1: Introduction.Chapter 2: The first-order delta-sigma modulator.Chapter 3: The second-order delta-sigma modulator.Chapter 4: Higher-order delta-sigma modulation.Chapter 5: Bandpass and quadrature delta-sigma modulation.Chapter 6: Implementation considerations for [Delta][Sigma] ADCs.Chapter 7: Delta-sigma DACs.Chapter 8: High-level design and simulation.Chapter 9: Example modulator systems.Appendix A: Spectral estimation.Appendix B: The delta-sigma toolbox.Appendix C: Noise in switched-capacitor delta-sigma data converters.
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Posted Content•
TL;DR: In this article, a procedure to demodulate analog signals encoded by a multicarrier modulator with slowly-varying carrier shapes was proposed, and it was shown that the asymptotic demodulation error can be made arbitrarily small.
Abstract: We propose a procedure to demodulate analog signals encoded by a multicarrier modulator, with slowly-varying carrier shapes. We prove that the asymptotic demodulation error can be made arbitrarily small. The intended application is the "sensorless" control of AC electric motors at or near standstill, through the decoding of the PWM-induced current ripple.
1 citations
12 Apr 2015
TL;DR: This work presents a general architecture for all-digital frequency synthesizers based on a frequency-shifted Σ/Δ modulator that can achieve spurs free spectrum within the band of interest and high dynamic range.
Abstract: This work presents a general architecture for all-digital frequency synthesizers based on a frequency-shifted Σ/Δ modulator. The synthesizers can achieve spurs free spectrum within the band of interest and high dynamic range. System level aspects of the synthesizers are discussed and MATLAB simulation results are presented.
1 citations
01 Dec 2008
TL;DR: A 1-V 190-muW delta-sigma modulator with chopper stabilization and bootstrapped switch is designed using a full digital 0.13-mum CMOS technology to reduce the output swings of each integrator and relax the DC gain requirement of the operational transconductance amplifier; hence saves power and reduces distortion.
Abstract: A 1-V 190-muW delta-sigma modulator with chopper stabilization and bootstrapped switch is designed using a full digital 0.13-mum CMOS technology. The fourth-order feedforward architecture is employed to reduce the output swings of each integrator and relax the DC gain requirement of the operational transconductance amplifier; hence saves power and reduces distortion. The core area excluding PAD is 0.9 times 0.64 mm2. The simulation results show that the modulator achieves 99.8 dB peak signal-to-quantization-noise ratio (SQNR) and -102 dB total harmonic distortions over the 20 kHz signal bandwidth with an OSR of 125.
1 citations
Cites background from "Understanding Delta-Sigma Data Conv..."
...With the ever-increasing demand for portable electronics and biomedical sensor systems, low-voltage low-power deltasigma data converters have been developing for more than a decade [1]....
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TL;DR: In this article, an analysis of sigma-delta modulator and its models (equivalent circuits) is performed, and a refined equivalent circuit of modulator is suggested.
Abstract: Analysis of sigma-delta modulator and its models (equivalent circuits) is performed. New refined equivalent circuit of modulator and its transfer function are suggested. Modeling of modulator is performed which confirms results of analysis.
1 citations
01 Nov 2011
TL;DR: In this article, an 15th order bandpass delta-sigma modulator for class-S power amplifiers is presented, based on a third order low pass prototype which is designed to meet the requirements for signal-to-noise ratio (SNR) of major mobile communication standards in a bandwidth of around 30 MHz.
Abstract: An 15th order bandpass delta-sigma modulator for class-S power amplifiers is presented. The modulator is based on a third order low pass prototype which is designed to meet the requirements for signal-to-noise ratio (SNR) of major mobile communication standards in a bandwidth of around 30 MHz. The transform z−1 → z−5 leads to a repetition of the low pass notch in the noise transfer function (NTF) at frequencies f = n/5f s , n = 1, 2, 3, 4, 5, &. Apart from sinc filtering due to rectangular output pulses the NTF shape is equal in all frequency bands. The two lower frequency bands at f = 1/5f s , 2/5 f s are independent from each other and can be used for concurrent transmission in the 450 MHz and 900 MHz band. The paper investigates the modulator with respect to the signal to noise ratio, the stability and the coding efficiency versus input amplitudes of tones in both frequency bands.
1 citations
Cites background from "Understanding Delta-Sigma Data Conv..."
...The substitution z → z transforms the modulator into a bandpass comb modulator [8] without increasing complexity (Fig....
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References
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TL;DR: Higher order modulators are shown not only to greatly reduce oversampling requirements for high-resolution conversion applications, but also to randomize the quantization noise, avoiding the need for dithering.
Abstract: Oversampling interpolative coding has been demonstrated to be an effective technique for high-resolution analog-to-digital (A/D) conversion that is tolerant of process imperfections. A novel topology for constructing stable interpolative modulators of arbitrary order is described. Analysis of this topology shows that with proper design of the modulator coefficients, stability is not a limitation to higher order modulators. Furthermore, complete control over placement of the poles and zeros of the quantization noise response allows treatment of the modulation process as a high-pass filter for quantization noise. Higher order modulators are shown not only to greatly reduce oversampling requirements for high-resolution conversion applications, but also to randomize the quantization noise, avoiding the need for dithering. An experimental fourth-order modulator breadboard demonstrates stability and feasibility, achieving a 90-dB dynamic range over the 20-kHz audio bandwidth with a sampling rate of 2.1 MHz. A generalized simulation software package has been developed to mimic time-domain behavior for oversampling modulators. Circuit design specifications for integrated circuit implementation can be deduced from analysis of simulated data. >
399 citations
TL;DR: It is shown that digital filters comprising cascades of integrate-and-dump functions can match the structure of the noise from sigma delta modulation to provide decimation with negligible loss of signal-to-noise ratio.
Abstract: Decimation is an important component of oversampled analog-to-digital conversion. It transforms the digitally modulated signal from short words occurring at high sampling rate to longer words at the Nyquist rate. Here we are concerned with the initial stage of decimation, where the word rate decreases to about four times the Nyquist rate. We show that digital filters comprising cascades of integrate-and-dump functions can match the structure of the noise from sigma delta modulation to provide decimation with negligible loss of signal-to-noise ratio. Explicit formulas evaluate particular tradeoffs between modulation rate, signal-to-noise ratio, length of digital words, and complexity of the modulating and decimating functions.
342 citations
TL;DR: This paper introduces a new method of analysis for deltasigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion, followed by an additive noise source representing distortion components.
Abstract: This paper introduces a new method of analysis for deltasigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion [7], followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.
284 citations
TL;DR: Simple algebraic expressions for this modulation noise and its spectrum in terms of the input amplitude are derived and can be useful for designing oversampled analog to digital converters that use sigma-delta modulation for the primary conversion.
Abstract: When the sampling rate of a sigma-delta modulator far exceeds the frequencies of the input signal, its modulation noise is highly correlated with the amplitude of the input. We derive simple algebraic expressions for this noise and its spectrum in terms of the input amplitude. The results agree with measurements taken on a breadboard circuit. This work can be useful for designing oversampled analog to digital converters that use sigma-delta modulation for the primary conversion.
255 citations
01 Mar 1993
TL;DR: The modulator of a bandpass analog/digital (A/D) converter, with 63 dB signal/noise for broadcast AM bandwidth signals centered at 455 kHz, has been implemented by modifying a commercial digital-audio sigma-delta ( Sigma Delta ) converter.
Abstract: The modulator of a bandpass analog/digital (A/D) converter, with 63 dB signal/noise for broadcast AM bandwidth signals centered at 455 kHz, has been implemented by modifying a commercial digital-audio sigma-delta ( Sigma Delta ) converter. It is the first reported fully monolithic implementation of bandpass noise shaping and has applications to digital radio. >
211 citations