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Über dieses Buch

This textbook is appropriate for use in graduate-level curricula in analog-to-digital conversion, as well as for practicing engineers in need of a state-of-the-art reference on data converters. It discusses various analog-to-digital conversion principles, including sampling, quantization, reference generation, nyquist architectures and sigma-delta modulation. This book presents an overview of the state of the art in this field and focuses on issues of optimizing accuracy and speed, while reducing the power level.

This new, third edition emphasizes novel calibration concepts, the specific requirements of new systems, the consequences of 22-nm technology and the need for a more statistical approach to accuracy. Pedagogical enhancements to this edition include additional, new exercises, solved examples to introduce all key, new concepts and warnings, remarks and hints, from a practitioner's perspective, wherever appropriate. Considerable background information and practical tips, from designing a PCB, to lay-out aspects, to trade-offs on system level, complement the discussion of basic principles, making this book a valuable reference for the experienced engineer.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
An analog-to-digital converter is an essential building block in modern signal processing. Both the analog-to-digital conversion and the digital-to-analog conversion are key functions for optimally exploiting the capabilities of the digital signal processing core. Three basic processes are distinguished in analog-to-digital conversion: the transition between the time-continuous domain and time-discrete domain, the quantization of the signal amplitude and the relation between physical quantities and numerical quantities.
Marcel Pelgrom

Chapter 2. Sampling

Abstract
Sampling is one of the main processes in an analog-to-digital converter. The sampling theory is examined and the crucial elements are extensively discussed. The relation with other techniques such as modulation and sampling of noise is described. The second section discusses the design of time-discrete filters. These filters form an important building block in several conversion structures especially in sigma-delta conversion. Down-sample filters transform the bit-stream format into a more usable pulse code format. The essential properties of finite impulse response and infinite impulse response filters are reviewed.
Marcel Pelgrom

Chapter 3. Sample and Hold

Abstract
The sample-and-hold circuit or track-and-hold circuit performs the sampling operation. These circuits have to operate at the highest signal levels and speeds, which makes their design a challenge. The chapter discusses first the specific metrics for these circuits, such as pedestal step, droop time, and hold-mode feed-through. The different elements: switch, capacitor, and buffer are discussed. Some architectures and often applied implementation schemes are shown. The trade-off between noise and distortion requires a careful balance to achieve the optimum performance.
Marcel Pelgrom

Chapter 4. Quantization

Abstract
Quantization is the second main process in conversion. This chapter deals with the mathematical derivation of quantization in several resolution ranges. Quantization results in several specific parameters: integral and differential linearities and derived problems such as monotonicity.The signal-to-noise ratio is also affected by quantization. Some special topics are the effect of dither and the relation between differential non-linearity and signal-to-noise.
Marcel Pelgrom

Chapter 5. Accuracy

Abstract
Technology is the foundation on which every circuit is build. Over the last four decades technology developments were dominated by the rapid evolution of CMOS technology. This chapter examines a few aspects that are relevant to the analog-to-digital designer. A major worry in design is the variation of parameter values. With the improved control over processing, the batch-to-batch variation is largely under control. However now a new class of phenomena has appeared: statistical variations. In conventional ICs, analog circuits with a differential operation (e.g., analog-to-digital converters) were already affected by this random parameter spread. The remaining variation between otherwise identical components is generally described by “mis-match” parameters. Next to these random phenomena also systematic errors called “offsets” play an increasingly important role. Understanding and mitigating these effects requires statistical means and models. Some sections describe the modeling of systematic and random effects that originate from physical, electrical, thermal, and lithography effects in devices causing intra-die variations.
Marcel Pelgrom

Chapter 6. Reference Circuits

Abstract
Every converter needs a reference quantity to link the numerical values on one side of the converter to a physical quantity on the other side. Several requirements are posed on the reference generator. The most common reference is based on the band-gap energy of silicon. The general scheme for a band-gap circuit is extensively discussed as well as the limitations of the various components. The effect of mismatch in this circuit is described at the hand of an example. Finally a few implementations of low-voltage band-gap circuits are shown.
Marcel Pelgrom

Chapter 7. Digital-to-Analog Conversion

Abstract
The two most important architectures for constructing a digital-to-analog converter are the unary and binary approach. Both approaches have their merits. Next to the architecture, the second choice is the domain in which the converter is realized: voltage, current, charge or time. Realizations in all these domains are discussed and their specific behavior is analyzed. The resistor string is an important conversion element as it constitutes the digital-to-analog function in a flash converter. Its dynamic behavior is essential for reaching high-speed performance. The binary counterpart of this converter is the R-2R architecture. The current-steering topology is the dominant realization for fast stand-alone digital-to-analog conversion. The properties of this converter are described and analyzed. Charge domain converters are mostly applied in lower-performance, low-power applications. Various topologies allow to choose between low area or better performance. A special section is dedicated to error sources and methods to improve the performance. The dynamic element matching, current calibration, and data weighted averaging methods are explained. A number of examples detail the design considerations and choices. Lay-out examples of commonly used structures are presented.
Marcel Pelgrom

Chapter 8. Nyquist Analog-to-Digital Conversion

Abstract
Several classifications exist of Nyquist-rate analog-to-digital converters. In this chapter the converters are subdivided into parallel search, sequential search, and linear search. Each of these architectures requires a comparator. Therefore this building block is extensively analyzed in all its aspects. The section is concluded with a comparator catalog.The full-flash converter is the conversion solution for the highest speed range. Moreover it is a building block for more complex converters. Variants such as gain stage, interpolation, and folding are analyzed and described.The sub-ranging methods and pipeline converters are the solutions for the medium speed range demands. Next to a treatise on the various aspects of the architecture an analysis is made of the error sources, calibration techniques, and design issues.In the next sections the successive approximation and linear topologies are discussed. These topologies are slower but receive today more attention as a massive parallelism allows them to compete with the performance of the pipeline converter. The issues associated with multiplexing are analyzed.Finally some less prominent ideas for conversion are briefly highlighted.
Marcel Pelgrom

Chapter 9. Time-Interleaving

Abstract
Time-interleaving allows to push the speed of the conversion to almost flash converter like values. The signal is split and processes a number of slower channels. The data stream is recombined in the digital domain. The problems associated with time-interleaving are the various errors that can occur: offsets, gain mismatches, sampling time differences, bandwidth variations, and for digital-to-analog conversion also reconstruction errors.
Marcel Pelgrom

Chapter 10. Sigma-Delta Modulation

Abstract
The sigma-delta modulator is a specific algorithm to convert low-bandwidth signals into a digital data stream. In the first section the effects of oversampling are described both for the analog-to-digital converter and for the analog-to-digital converter. The next step is the noise shape topology. The feedback mechanism that is applied to the quantization errors allows to free a fraction of the bandwidth of this error energy. The basic mechanisms in the noise shaper are applied to show the effects of increasing the oversample rate and increasing the order of the feedback filter. A similar approach is adopted to deal with the sigma-delta topology. The time-discrete implementation allows to design first and second order modulators. The main extension towards higher orders is found in the cascaded sigma-delta modulator. The time-continuous sigma-delta modulators use simple transconductance-capacitor filters and their properties differ in a number of aspects from the time-discrete variants. Some implementation aspects are given. The discussion on the advantages of multi-bit conversion is summarized.
Marcel Pelgrom

Chapter 11. Characterization and Specification

Abstract
The specification of the converter is a dominant mechanism to align the wishes of the user to the possibilities of the designer. Directly coupled to the specification is the measurement technique that serves to establish a numerical value for a theoretical concept. This chapter discusses the fundamentals of the characterization and measurement techniques, such as histogram testing.
Marcel Pelgrom

Backmatter

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