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Understanding Delta-Sigma Data Converters

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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Citations
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Proceedings ArticleDOI
02 Nov 2015
TL;DR: In this article, the authors present the design and implementation of electro-mechanical continuous-time bandpass and lowpass ΔΣ-modulators for closed-loop readout of vibratory MEMS gyroscopes.
Abstract: This paper presents the design and implementation of electro-mechanical continuous-time bandpass and lowpass ΔΣ-modulators for closed-loop readout of vibratory MEMS gyroscopes. These concepts improve the performance of the readout system in terms of susceptibility to temperature and sensor parameter variations compared to open-loop solutions. Additionally, the linearity and the dynamic range are improved while the power consumption is low. Measurement results are shown of both readout concepts, which demonstrate the competitiveness and the functionality of the readout interfaces.

5 citations


Cites background from "Understanding Delta-Sigma Data Conv..."

  • ...3 Basics of -Modulation In general -M consists of a loop filter resulting in the noise-shaping behavior of the system and a quantizer with a low number of quantization steps [6]....

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  • ...[6] operational amplifiers (OpAmp) do not need to settle to switched values....

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Proceedings ArticleDOI
02 Oct 2009
TL;DR: A novel design for a Digital Delta Sigma Modulator (DDSM) which produces a spur-free spectrum for all constant inputs with higher order shaped additive LSB dither and can increase the order of noise shaping of the applied dither to that of the modulator without any spurious tones appearing in the spectrum.
Abstract: This paper presents a novel design for a Digital Delta Sigma Modulator (DDSM) which produces a spur-free spectrum for all constant inputs with higher order shaped additive LSB dither. We can increase the order of noise shaping of the applied dither to that of the modulator without any spurious tones appearing in the spectrum. The result is confirmed by simulation.

5 citations


Cites background from "Understanding Delta-Sigma Data Conv..."

  • ...By contrast, the stochastic approach to whiten the quantization noise is to use a “random” dither signal to disrupt periodic cycles [2], [3], [7]....

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  • ...A DDSM receives an n0-bit digital input signal x and delivers an m-bit digital output signal y; generally, m is significantly less than n0 [1]– [3]....

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Proceedings ArticleDOI
03 Mar 2008
TL;DR: A fourth-order single-bit delta-sigma modulator with wide dynamic range suitable for distributed sensor and audio codec applications and a maximum dynamic range of 99 dB within a 20- kHz bandwidth is presented.
Abstract: In this paper, we present a fourth-order single-bit delta-sigma modulator with wide dynamic range. This modulator is suitable for distributed sensor and audio codec applications. This chip was fabricated in a 0.18- mum one-poly, four-metal CMOS technology, and occupies 1.22-mm2 active area. The circuit is clocked at 3.2 MHz and the overall power consumption is 5.6 mW from a 3.0 V power supply. Experimental results show a maximum dynamic range of 99 dB within a 20- kHz bandwidth.

5 citations


Cites background or methods from "Understanding Delta-Sigma Data Conv..."

  • ...The DR is related to OSR, n, and B, according to [2]:...

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  • ...The DR of a delta-sigma modulator, where the resolution is limited by the kT/C noise of the first switched-capacitor integrator stage, is given by [2]:...

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  • ...FOM of a delta-sigma modulator is defined as [2]:...

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Proceedings ArticleDOI
01 Aug 2018
TL;DR: The proposed architecture uses a monotonic switching procedure which allows fewer conversion steps than for a conventional SAR ADCs and provides first-order noise shaping, which can improve the ADC’s linearity even for a small oversampling ratio (OSR).
Abstract: This paper presents an active noise-shaping successive-approximation-register analog-to-digital converter. Instead of binary-weighted capacitors, it uses two equal-valued capacitors as a digital-to-analog converter (DAC). Thus, the capacitance spread in the DAC is 1, much smaller than that of the conventional binary-weighted capacitor array, and hence the mismatch error can be greatly reduced. The circuit provides first-order noise shaping, which can improve the ADC’s linearity even for a small oversampling ratio (OSR). Also, the proposed architecture uses a monotonic switching procedure which allows fewer conversion steps than for a conventional SAR ADCs. The ADC was fabricated in 0.18 um CMOS technology. For a 2kHz bandwidth, it achieved a 78.8 dB SNDR. It consumes 74.2uW power from 1.5V power supply.

5 citations


Cites background from "Understanding Delta-Sigma Data Conv..."

  • ...The proposed active SAR ADC, described in Section III, can provide ideal first-order noise shaping [5], which can significantly improve the linearity of the ADC....

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  • ...The finite DC gain of the integrator is critical for the noise shaping [5] [7], since it will cause error between the analog and digital realizations of NTF....

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References
More filters
Journal ArticleDOI
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

Journal ArticleDOI
James C. Candy1
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

Journal ArticleDOI
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

Book ChapterDOI
James C. Candy1, O. Benjamin1
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

Journal ArticleDOI
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