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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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Journal ArticleDOI
TL;DR: A multi-step incremental ADC with extended binary counting is proposed, which achieves high accuracy by splitting one conversion cycle into two serial steps and extends the accuracy to 18 bits by a binary counting technique.
Abstract: A multi-step incremental ADC (IADC) with extended binary counting is proposed. It achieves high accuracy by splitting one conversion cycle into two serial steps. During the first step, the ADC works as a first-order IADC (IADC1). The second step reuses the single integrator and extends the accuracy to 18 bits by a binary counting technique. For the same accuracy, the conversion cycle is shortened by a factor of more than 28 as compared with the single-step IADC.

7 citations

Proceedings ArticleDOI
09 May 2014
TL;DR: In this paper, the use of delta-sigma modulators in visible light OFDM systems to convert continuous magnitude OFDM symbols into LED driver signals was proposed, which has the communication theory advantages of OFDM along with the practical analog and optical advantages of simple two level driver signals.
Abstract: Visible light communications (VLC) are motivated by the radio-frequency (RF) spectrum crunch and fast-growing solid-state lighting technology. VLC relies on white light emitting diodes (LEDs) to provide communication and illumination simultaneously. Simple two-level on-off keying (OOK) and pulse-position modulation (PPM) are supported in IEEE standard due to their compatibility with existing constant current LED drivers, but their low spectral efficiency have limited the achievable data rates of VLC. Orthogonal frequency division multiplexing (OFDM) has been applied to VLC due to its high spectral efficiency and ability to combat inter-symbol-interference (ISI). However, VLC-OFDM inherits the disadvantage of high peak-to-average power ratio (PAPR) from RF-OFDM. Besides, the continuous magnitude of OFDM signals requires complicated mixed-signal digital-to-analog converter (DAC) and modification of LED drivers. We propose the use of delta-sigma modulators in visible light OFDM systems to convert continuous magnitude OFDM symbols into LED driver signals. The proposed system has the communication theory advantages of OFDM along with the practical analog and optical advantages of simple two level driver signals. Simulation results are provided to illustrate the proposed system.

7 citations

Journal ArticleDOI
TL;DR: A novel multi mode low pass hybrid continuous/discrete time delta sigma modulator which is suitable for low power wide band applications and using the noise-shaping enhancement technique which can increase the performance of the modulator without using analog active blocks.
Abstract: A novel multi mode low pass hybrid continuous/discrete time delta sigma modulator which is suitable for low power wide band applications is presented in this article. The proposed topology can adapt itself for operating in various signal bandwidths as well as different signal to noise plus distortion ratios (SNDRs). The novelty of the proposed modulator lies in the fact that several techniques have been employed simultaneously that not only can reduce the power consumption, but also it can increase the performance of the modulator. Continuous time integrator is utilized to alleviate the specs for the first stage op-amp. The modulator employs an op-amp sharing technique, which decreases the power consumption dramatically due to elimination of the power hungry adder before the quantizer in the feed forward topology. Another attractive advantage of the proposed modulator is using the noise-shaping enhancement technique which can increase the performance of the modulator without using analog active blocks. The unused block of the modulator can be made inactive to achieve less power dissipation. Behavioral simulations in MATLAB environment show the SNDR of 91/86/73 dB over 0.2/2/20 MHz signal bandwidth.

7 citations

Proceedings Article
18 Jul 2010
TL;DR: Simulation results confirmed the feasibility of the implementation of such a compensation filter for increasing the image rejection performance of the Low-IF receiver front end and the performance of compensation filter based on LMS algorithm can be verified efficiently during the system simulation.
Abstract: Insufficient image-rejection due to I/Q mismatch considerably degrades the performance of modern wireless communication systems. This paper presents a SystemC-AMS front-to back-end modeling approach in a Low-IF receiver system with a digital adaptive filter for I/Q mismatch compensation. With the proposed approach, the non-ideal behavioral of the analog building blocks concerning I/Q imbalance is mapped and the performance of compensation filter based on LMS algorithm can be verified efficiently during the system simulation. Simulation results confirmed the feasibility of the implementation of such a compensation filter for increasing the image rejection performance of the Low-IF receiver front end.

7 citations


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

  • ...In this case, the overall IRR of the front-end behind the down conversion is according to [10]:...

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Journal ArticleDOI
TL;DR: In this paper, the authors describe all-digital enhancements for digital fractional-nodes phase-locked loops (PLLs) based on delta-sigma frequency-to-digital converters (FDCs).
Abstract: This paper describes all-digital enhancements for digital fractional- ${N}$ phase-locked loops (PLLs) based on delta-sigma ( $\Delta \Sigma $ ) frequency-to-digital converters (FDCs). The enhancements include an improved dual-mode ring oscillator (DMRO)-based $\Delta \Sigma $ FDC architecture and a digital background calibration technique that compensates for the $\Delta \Sigma $ FDC’s forward path gain error. The improved $\Delta \Sigma $ FDC has significantly relaxed timing constraints and a $3\times $ smaller phase-frequency detector output pulse-width span relative to the prior art, which make it simpler to implement and amenable to higher-frequency reference signals. The calibration technique compensates for non-ideal DMRO frequencies in the digital domain. It eliminates the need to tune the DMRO instantaneous frequencies as a function of the PLL output frequency, thereby simplifying the DMRO implementation, and it also improves the phase noise performance of PLLs with high loop bandwidths.

7 citations

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