This book demonstrates why highly-digital CMOS time-encoding analog-to-digital converters incorporating voltage-controlled oscillators (VCOs) and time-to-digital converters (TDCs) are a good alternative to traditional switched-capacitor S-D modulators for power-efficient sensor, biomedical and communications applications. The authors describe the theoretical foundations and design methodology of such time-based ADCs from the basics to the latest developments. While most analog designers might notice some resemblance to PLL design, the book clearly highlights the differences to standard PLL circuit design and illustrates the design methodology with practical circuit design examples. Describes in detail the design methodology for CMOS time-encoding analog-to-digital converters that can be integrated along with digital logic in a nanometer System on Chip; Assists analog designers with the necessary change in design paradigm, highlighting differences between designing time-based ADCs and traditional analog circuits like switched-capacitor converters and PLLs; Uses a highly-visual, tutorial approach to the topic, including many practical examples of techniques introduced.
This book introduces the concept of voltage-controlled-oscillator (VCO)-based analog-to-digital converters (ADCs). Detailed explanation is given of this promising new class of high resolution and low power ADCs, which use time quantization as opposed to traditional analog-based (i.e. voltage) ADCs.
Today's complex electronic systems with billions of transistors on a single die are enabled by the aggressive scaling down of the device feature size at an exponential rate as predicted by the Moore's law. Digital circuits benefit from technology scaling to become faster, more energy efficient as well as more area efficient as the feature size is scaled down. Moreover, digital design also benefits from mature CAD tools that simplify the design and cross-technology porting of complex systems, leveraging on a cell-based design methodology. On the other hand, the design of analog circuits is getting increasingly difficult as the feature size scales down into the deep nanometer regime due to a variety of reasons like shrinking voltage headroom, reducing intrinsic gain of the devices, increasing noise coupling between circuit nodes due to shorter distances etc. Furthermore, analog circuits are still largely designed with a full custom design ow that makes their design and porting tedious, slow, and expensive. In this context, it is attractive to consider realizing analog/mixed-signal circuits using standard digital components. This leads to scaling-friendly mixed-signal blocks that can be designed and ported using the existing CAD framework available for digital design. The concept is already being applied to mixed-signal components like frequency synthesizers where all-digital architectures are synthesized using standard cells as basic components. This can be extended to other mixed-signal blocks like digital-to-analog and analog to- digital converters as well, where the latter is of particular interest in this thesis. A voltage-controlled oscillator (VCO)-based analog-to-digital converter (ADC) is an attractive architecture to achieve all-digital analog-to digital conversion due to favorable properties like shaping of the quantization error, inherent anti-alias filtering etc. Here a VCO operates as a signal integrator as well as a quantizer. A converter employing a ring oscillator as the VCO lends itself to an all-digital implementation. In this dissertation, we explore the design of VCO-based ADCs synthesized using digital standard cells with the long-term goal of achieving high performance data converters built from low accuracy switch components. In a first step, an ADC is designed using vendor supplied standard cells and fabricated in a 65 nm CMOS process. The converter delivers an 8-bit ENOB over a 25 MHz bandwidth while consuming 3.3 mW of power resulting in an energy efficiency of 235 fJ/step (Walden FoM). Then we utilize standard digital CAD tools to synthesize converter designs that are fully described using a hardware description language. A polynomial-based digital post-processing scheme is proposed to correct for the VCO nonlinearity. In addition, pulse modulation schemes like delta modulation and asynchronous sigma-delta modulation are used as a signal pre-coding scheme, in an attempt to reduce the impact of VCO nonlinearity on converter performance. In order to investigate the scaling benefits of all-digital data conversion, a VCO-based converter is designed in a 28 nm CMOS process. The design delivers a 13.4-bit ENOB over a 5 MHz bandwidth achieving an energy efficiency of 4.3 fJ/step according to post-synthesis schematic simulation, indicating that such converters have the potential of achieving good performance in deeply scaled processes by exploiting scaling benefits. Furthermore, large conversion errors caused by non-ideal sampling of the oscillator phase are studied. An encoding scheme employing ones counters is proposed to code the sampled ring oscillator output into a number, which is resilient to a class of sampling induced errors modeled by temporal reordering of the transitions in the ring. The proposed encoding reduces the largest error caused by random reordering of up to six subsequent bits in the sampled signal from 31 to 2 LSBs. Finally, the impact of process, voltage, and temperature (PVT) variations on the performance while operating the converter from a subthreshold supply is investigated. PVT-adaptive solutions are suggested as a means to achieve energy-efficient operation over a wide range of PVT conditions.
Micro-electronics and so integrated circuit design are heavily driven by technology scaling. The main engine of scaling is an increased system performance at reduced manufacturing cost (per system). In most systems digital circuits dominate with respect to die area and functional complexity. Digital building blocks take full - vantage of reduced device geometries in terms of area, power per functionality, and switching speed. On the other hand, analog circuits rely not on the fast transition speed between a few discrete states but fairly on the actual shape of the trans- tor characteristic. Technology scaling continuously degrades these characteristics with respect to analog performance parameters like output resistance or intrinsic gain. Below the 100 nm technology node the design of analog and mixed-signal circuits becomes perceptibly more dif cult. This is particularly true for low supply voltages near to 1V or below. The result is not only an increased design effort but also a growing power consumption. The area shrinks considerably less than p- dicted by the digital scaling factor. Obviously, both effects are contradictory to the original goal of scaling. However, digital circuits become faster, smaller, and less power hungry. The fast switching transitions reduce the susceptibility to noise, e. g. icker noise in the transistors. There are also a few drawbacks like the generation of power supply noise or the lack of power supply rejection.
This complete update of a classic handbook originally created by Analog Devices and never previously published offers the most complete and up-to-date reference available on data conversion, from the world authority on the subject. It describes in depth the theory behind and the practical design of data conversion circuits. It describes the different architectures used in A/D and D/A converters - including many advances that have been made in this technology in recent years - and provides guidelines on which types are best suited for particular applications. It covers error characterization and testing specifications, essential design information that is difficult to find elsewhere. The book also contains a wealth of practical application circuits for interfacing and supporting A/D and D/A converters within an electronic system. In short, everything an electronics engineer needs to know about data converters can be found in this volume, making it an indispensable reference with broad appeal. The accompanying CD-ROM provides software tools for testing and analyzing data converters as well as a searchable pdf version of the text. * brings together a huge amount of information impossible to locate elsewhere. * many recent advances in converter technology simply aren't covered in any other book. * a must-have design reference for any electronics design engineer or technician
Our understanding of nature is often through nonuniform observations in space or time. In space, one normally observes the important features of an object, such as edges. The less important features are interpolated. History is a collection of important events that are nonuniformly spaced in time. Historians infer between events (interpolation) and politicians and stock market analysts forecast the future from past and present events (extrapolation). The 20 chapters of Nonuniform Sampling: Theory and Practice contain contributions by leading researchers in nonuniform and Shannon sampling, zero crossing, and interpolation theory. Its practical applications include NMR, seismology, speech and image coding, modulation and coding, optimal content, array processing, and digital filter design. It has a tutorial outlook for practising engineers and advanced students in science, engineering, and mathematics. It is also a useful reference for scientists and engineers working in the areas of medical imaging, geophysics, astronomy, biomedical engineering, computer graphics, digital filter design, speech and video processing, and phased array radar.
MOS technology has rapidly become the de facto standard for mixed-signal integrated circuit design due to the high levels of integration possible as device geometries shrink to nanometer scales. The reduction in feature size means that the number of transistor and clock speeds have increased significantly. In fact, current day microprocessors contain hundreds of millions of transistors operating at multiple gigahertz. Furthermore, this reduction in feature size also has a significant impact on mixed-signal circuits. Due to the higher levels of integration, the majority of ASICs possesses some analog components. It has now become nearly mandatory to integrate both analog and digital circuits on the same substrate due to cost and power constraints. This book presents some of the newer problems and opportunities offered by the small device geometries and the high levels of integration that is now possible. The aim of this book is to summarize some of the most critical aspects of high-speed analog/RF communications circuits. Attention is focused on the impact of scaling, substrate noise, data converters, RF and wireless communication circuits and wireline communication circuits, including high-speed I/O. Contents: Achieving Analog Accuracy in Nanometer CMOS (M P Flynn et al.); Self-Induced Noise in Integrated Circuits (R Gharpurey & S Naraghi); High-Speed Oversampling Analog-to-Digital Converters (A Gharbiya et al.); Designing LC VCOs Using Capacitive Degeneration Techniques (B Jung & R Harjani); Fully Integrated Frequency Synthesizers: A Tutorial (S T Moon et al.); Recent Advances and Design Trends in CMOS Radio Frequency Integrated Circuits (D J Allstot et al.); Equalizers for High-Speed Serial Links (P K Hanumolu et al.); Low-Power, Parallel Interface with Continuous-Time Adaptive Passive Equalizer and Crosstalk Cancellation (C P Yue et al.). Readership: Technologists, scientists, and engineers in the field of high-speed communication circuits. It can also be used as a textbook for graduate and advanced undergraduate courses.
This book presents the a scientific discussion of the state-of-the-art techniques and designs for modeling, testing and for the performance analysis of data converters. The focus is put on sustainable data conversion. Sustainability has become a public issue that industries and users can not ignore. Devising environmentally friendly solutions for data conversion designing, modeling and testing is nowadays a requirement that researchers and practitioners must consider in their activities. This book presents the outcome of the IWADC workshop 2011, held in Orvieto, Italy.
This new edition introduces operation and design techniques for Sigma-Delta converters in physical and conceptual terms, and includes chapters which explore developments in the field over the last decade Includes information on MASH architectures, digital-to-analog converter (DAC) mismatch and mismatch shaping Investigates new topics including continuous-time ΔΣ analog-to-digital converters (ADCs) principles and designs, circuit design for both continuous-time and discrete-time ΔΣ ADCs, decimation and interpolation filters, and incremental ADCs Provides emphasis on practical design issues for industry professionals
