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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Understanding Delta-Sigma Data Converters

The author examines the practical design criteria for implementing oversampled analog/digital converters based on second-order sigma-delta ( Sigma Delta ) modulation. Behavioral models that include representation of various circuit impairments are established for each of the functional building blocks comprising a second-order Sigma 2gD modulator. Extensive simulations based on these models are then used to establish the major design criteria for each of the building blocks. As an example, these criteria are applied to the design of a modulator that has been integrated in a 3- mu m CMOS technology. An experimental prototype operates from a single 5-V supply, dissipates 12 mW, occupies an area of 0.77 mm/sup 2/, and has achieved a measured dynamic range of 89 dB. >

The design of sigma-delta modulation analog-to-digital converters

Using sigma-delta A/D methods, high resolution can be obtained for only low to medium signal bandwidths. This article describes conventional A/D conversion, as well as its performance modeling. We then look at the technique of oversampling, which can be used to improve the resolution of classical A/D methods. We discuss how sigma-delta converters use the technique of noise shaping in addition to oversampling to allow high resolution conversion of relatively low bandwidth signals. We examine the use of sigma-delta converters to convert narrowband bandpass signals with high resolution. Several parallel sigma-delta converters, which offer the potential of extending high resolution conversion to signals with higher bandwidths, are also described.

An overview of sigma-delta converters

Several results describing the behavior of quantization noise in a unified and simplified manner are discussed. Exact formulas for quantizer noise spectra are developed. They are applied to a variety of systems and inputs, including scalar quantization (PCM), dithered PCM, sigma-delta modulation, dithered sigma-delta modulation, two-stage sigma-delta modulation, and second-order sigma-delta modulation. >

Quantization noise spectra

This paper presents a complete set of blocks implemented in the popular MATLAB SIMULINK environment, which allows designers to perform time-domain behavioral simulations of switched-capacitor (SC) sigma-delta (/spl Sigma//spl Delta/) modulators. The proposed set of blocks takes into account most of the SC /spl Sigma//spl Delta/ modulator nonidealities, such as sampling jitter, kT/C noise, and operational amplifier parameters (white noise, finite DC gain, finite bandwidth, slew rate and saturation voltages). For each block, a description of the considered effect as well as all of the implementative details are provided. The proposed simulation environment is validated by comparing the simulated behavior with the experimental results obtained from two actual circuits, namely a second-order low-pass and a sixth-order bandpass SC /spl Sigma//spl Delta/ modulator.

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Behavioral modeling of switched-capacitor sigma-delta modulators

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.

/pdf/an-analysis-of-nonlinear-behavior-in-delta-sigma-modulators-43rb1chldv.pdf

An analysis of nonlinear behavior in delta - sigma modulators

ZSIM, a nonlinear Z-domain simulator for sampled-data systems, is presented and verified. ZSIM integrates analytic tools, a difference equation simulator, a table-based nonlinear Z-domain simulator, and digital signal processing into a workstation environment to provide fast and accurate simulation of delta-sigma modulators. The use of table-based simulation allows simulation of circuit nonidealities including clock feedthrough and saturation. Benchmark comparisons of difference equation simulations and table-based simulations are presented for delta-sigma modulators suitable for use in voice-band coders. >

Table-based modeling of delta-sigma modulators using ZSIM

The program ZSIM (nonlinear Z-domain simulator) is used to explore the benefits and limitations of a table-based approach to the simulation of delta-sigma modulators with switched-capacitor integrators. Simulations demonstrating the effects of clock feedthrough and incomplete settling are presented, as are simulations demonstrating the importance of using an accurate and charge-conservative circuit simulator for the table point transient simulations. The methods used are appropriate for other discrete-time systems where simulation of system-level performance based on the results of transient circuit simulation is desired. >

http://ieeexplore.ieee.org/iel1/31/1898/00052741.pdf

Table-based simulation of delta-sigma modulators

The effects of radiation exposure on the performance of CMOS integrated circuits are difficult to predict and to simulate due to the bias-dependent device parameter shifts. Simulation methodologies for identification of failure mechanisms and performance estimation are developed. These simulation algorithms are implemented in the PARA simulator for switch-level simulation of radiation effects. Simulation results for test circuits are presented that prove that accurate estimations are possible without CPU-intensive simulation programs. >

Switch-level simulation of total dose effects on CMOS VLSI circuits

Table-based transistor modeling techniques require a current table and a charge/capacitance table for each device geometry at each simulation temperature. Simple interpolation methods can be used to construct any current table from a small basis set of tables. A database of 32 current tables (two widths, four lengths, measured at four temperatures) is sufficient to span the space defined by these sample points. The technique provides an accurate rendering of the transistor current above threshold without the need for complex parameter optimization and without the need for an exhaustive database of current tables. >

J.J. Paulos

Papers

An analysis of nonlinear behavior in delta - sigma modulators

Table-based modeling of delta-sigma modulators using ZSIM

Table-based simulation of delta-sigma modulators

Switch-level simulation of total dose effects on CMOS VLSI circuits

Interpolation of MOSFET table data in width, length, and temperature