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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
More filters
Journal ArticleDOI
TL;DR: A new structure based on the Noise Coupled time-interleaved delta-sigma modulator is proposed to increase the overall noise transfer function order without any additional active element.
Abstract: An analog-to-digital converter based on the time-interleaved delta-sigma modulator is a proper method for high-speed ADCs. Time-interleaved delta-sigma modulators (TIDSM) can be successfully implemented with the development of the block digital filtering (BDF) technique. In this method, M mutually cross-connection delta-sigma modulators are used, with each one operating at a sampling rate of $${\text{f}}_{\text{s}}$$ hence, the effective sampling rate will be $${\text{M}}*{\text{f}}_{\text{s}}$$ However, SNDR is approximately equal to the single path standard structure. In this paper, a new structure based on the Noise Coupled time-interleaved delta-sigma modulator is proposed to increase the overall noise transfer function order without any additional active element. This improvement is analytically verified and then validated using simulations. Also, some practical issues regarding the implementation of the proposed structure, such as, finite op-amp’s gain and mismatching effects are discussed. Also, analyzes and some practical solutions are presented. The results of the simulation at the system level show that the SNDR of the proposed first-order two-channel structure is 18 dB better than its BDF technique counterpart, for the second-order two-channel TIDSM, the SNDR of the proposed structure is 13 dB better than that of the BDF technique.

4 citations

Proceedings ArticleDOI
Davud Asemani1, J. Oksman1
21 Nov 2007
TL;DR: It is possible only in the TDM case that a blind deconvolution method is employed for adaptively compensating the realization errors and the input-output relationship is demonstrated to be Linear Time-Invariant for theTDM HFB, but it is non-LTI in the classical HFB case.
Abstract: In this paper, the Time-Division Multiplexing (TDM) architecture for the Hybrid Filter Bank (HFB) A/D Converters (ADCs) is studied in the time domain. Giving a brief survey on the TDM structure, the classical and TDM HFB-based ADCs are compared in terms of the output resolution for some input signals. To study the sensitivity to the realization errors, both structures are simulated assuming the same realization errors in the analysis filter banks. The TDM HFB-based ADC exhibits a better performance either in the presence or in the absence of realization errors than the classical one. Besides, the input-output relationship is demonstrated to be Linear Time-Invariant (LTI) for the TDM HFB, but it is non-LTI in the the classical HFB case. Thus, it is possible only in the TDM case that a blind deconvolution method is employed for adaptively compensating the realization errors.

4 citations

Journal ArticleDOI
TL;DR: It is found that the noise transfer function (NTF) implemented by the modulator can be optimised for either accuracy or integrator signal excursion, based on the requirements of the target application.
Abstract: This paper presents a comparison of incremental delta-sigma analogue-to-digital converters for integrated temperature sensing applications. The characteristics of bipolar transistor-based temperature sensing front-ends place specific requirements on the modulator loop architecture. Single loop delta-sigma architecture that removes the input signal from the internal loop by the addition of a feedforward path to the quantiser has been investigated thoroughly. It is found that the Noise Transfer Function (NTF) implemented by the modulator can be optimised for either accuracy or integrator signal excursion, based on the requirements of the target application.

4 citations

DissertationDOI
01 Jan 2008

4 citations


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

  • ...15: Generated pulses by a NRZ DAC (a), a RZ DAC (b) and a controlled RZ DAC (c) counterpart, whose clock rate is limited by the op-amp settling requirements [47]....

    [...]

Proceedings ArticleDOI
01 Aug 2006
TL;DR: A new design methodology for high order multi-bit continuous time Delta Sigma modulators is proposed and it provides a crystal-clear argument for the selection of the coefficients of the modulator.
Abstract: In this paper a new design methodology for high order multi-bit continuous time Delta Sigma modulators is proposed. It provides a crystal-clear argument for the selection of the coefficients of the modulator. The strategy of this paper is to design the modulator in z-domain and then to convert the modulator to s-domain.

4 citations


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

  • ...It is proven that the cascade and multi-bit modulators are two beneficial structures for the design ofthe high order DSM's [2]....

    [...]

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