M. Vogels

Bio: M. Vogels is an academic researcher from Katholieke Universiteit Leuven. The author has contributed to research in topics: Delta-sigma modulation & Delta modulation. The author has an hindex of 8, co-authored 18 publications receiving 161 citations.

An analytical integration method for the simulation of continuous-time /spl Delta//spl Sigma/ modulators

Abstract: Circuit-level simulation of /spl Delta//spl Sigma/ modulators is a time-consuming task, taking one or more days for meaningful results. While there are a great variety of techniques and tools that speed up the simulations for discrete-time /spl Delta//spl Sigma/ modulators, there is no rigorous methodology implemented in a tool to efficiently simulate and design the continuous-time counterpart. Nevertheless, in today's low-power, high-accuracy and/or very high-speed demands for A-to-D converters, designers are often forced to resort to the use of continuous-time /spl Delta//spl Sigma/ topologies. In this paper, we present a method for the high-level simulation of continuous-time /spl Delta//spl Sigma/ modulators as needed in top-down design and high-level modulator optimization. The method is based on analytical integration using behavioral models and exhibits the best tradeoff between accuracy, speed, and extensibility in comparison with other possible techniques that are reviewed briefly in this work. This methodology has been implemented in a user-friendly tool. Nonidealities such as finite gain, finite GBW, output impedance, and also nonlinearities, such as clipping, harmonic distortion, and the important effect of jitter are modeled. Finally, the tool was used to carry out some design-relevant experiments, illustrating the straightforward way of obtaining and exploring design tradeoffs at the modulator architectural level.

Architectural selection of A/D converters

Abstract: A method for the architectural selection of analog to digital (A/D) converters based on a generic figure of merit is described. First a figure of merit for the power consumption is introduced. This figure of merit includes both target specifications and technology data and has five generic parameters. The values of these generic parameters can be estimated by analyzing the different converter structures or by means of a fitting procedure using data from published designs. It is shown that the generic parameters have different values for different types of converters. Therefore the trade-off between speed, resolution, power dissipation and technology parameters depends on the type of converter. It is shown that the calculated figures of merit of the published designs, together with the calculated global trade-off comprise a surface in the (5 dimensional) design space. This surface makes it possible to accurately predict the power consumption and select the best converter solution for a certain target application. This can then serve as a first step in data converter synthesis or as a power estimator during high-level system design exploration.

Modeling and Simulation of a Sigma-Delta Digital to Analog Converter Using VHDL-AMS

Abstract: Sigma-Delta digital to analog converters are less vulnerable to circuit imperfections than their A/D counterparts because they have their noise-shaping loop all in the digital domain. Still the analog part of the system (basically a low-pass filter) can degrade the overall performance, especially in the case of multi-bit converters. This paper presents a way of identifying and simulating the major noise and harmonics contributions of the system using VHDL-AMS. The resulting system-level model can be used to explore different architectures in the digital domain and to determine the specifications of the different building blocks.

A behavioral simulation tool for continuous-time ΔΣ modulators

Abstract: Circuit--level simulation of ΔΣ modulators is a time--consuming task (taking one or more days for meaningful results). While there are a great variety of techniques and tools that speed up the simulations for discrete--time (DT) ΔΣ modulators, there is no rigorous methodology implemented in a tool to efficiently simulate and design the continuous--time (CT) counterpart. Yet, in todays low--power, high--accuracy and/or very high--speed demands for A--to--D converters, designers are often forced to resort to the use of CT ΔΣ topologies. In this paper, we present a method for the high--level simulation of continuous--time ΔΣ modulators that is based on behavioral models and which exhibits the best trade--off between accuracy, speed and extensibility compared to other possible techniques that are reviewed briefly in this work. A user--friendly tool, implementing this methodology, is then presented. Nonidealities such as finite gain, finite GBW, output impedance and also nonlinearities such as clipping, harmonic distortion and the important effect of jitter are modeled. Finally, experiments were carried out using the tool, exploring important design trade--offs.

A behavioral simulation tool for continuous-time /spl Delta//spl Sigma/ modulators

Abstract: Circuit-level simulation of /spl Delta//spl Sigma/ modulators is a time-consuming task (taking one or more days for meaningful results). While there are a great variety of techniques and tools that speed up the simulations for discrete-time (DT) /spl Delta//spl Sigma/ modulators, there is no rigorous methodology implemented in a tool to efficiently simulate and design the continuous-time (CT) counterpart. Yet, in todays low-power, high-accuracy and/or very high-speed demands for A-to-D converters, designers are often forced to resort to the use of CT /spl Delta//spl Sigma/ topologies. In this paper, we present a method for the high-level simulation of continuous-time /spl Delta//spl Sigma/ modulators that is based on behavioral models and which exhibits the best trade-off between accuracy, speed and extensibility compared to other possible techniques that are reviewed briefly in this work. A user-friendly tool, implementing this methodology, is then presented. Nonidealities such as finite gain, finite GBW, output impedance and also nonlinearities such as clipping, harmonic distortion and the important effect of jitter are modeled. Finally, experiments were carried out using the tool, exploring important design trade-offs.

Embedded System Design

Abstract: Until the late eighties, information processing was associated with large mainframe computers and huge tape drives. During the nineties, this trend shifted towards information processing with personal computers, or PCs. The trend towards miniaturization continues. In the future, most of the information processing systems will be quite small and embedded into larger products such as transportation and fabrication equipment. Hence, these kinds of systems are called embedded systems. It is expected that the total market volume of embedded systems will be significantly larger than that of traditional information processing systems such as PCs and mainframes. Embedded systems share a number of common characteristics. For example, they must be dependable, efficient, meet real-time constraints and require customized user interfaces (instead of generic keyboard and mouse interfaces). Therefore, it makes sense to consider common principles of embedded system design. Embedded System Design starts with an introduction into the area and a survey of specification languages for embedded systems.A brief overview is provided of hardware devices used for embedded systems and also presents the essentials of software design for embedded systems. Real-time operating systems and real-time scheduling are covered briefly.Techniques for implementing embedded systems are also discussed, using hardware/software codesign. It closes with a survey on validation techniques. Embedded System Designcan be used as a text book for courses on embedded systems and as a source which provides pointers to relevant material in the area for PhD students and teachers. The book assumes a basic knowledge of information processing hardware and software.

Sigma-Delta Modulators: Tutorial Overview, Design Guide, and State-of-the-Art Survey

Abstract: This paper presents a tutorial overview of ΣΔ modulators, their operating principles and architectures, circuit errors and models, design methods, and practical issues. A review of the state of the art on nanometer CMOS implementations is described, giving a survey of cutting-edge ΣΔ architectures, with emphasis on their application to the next generation of wireless telecom systems.

Hierarchical Modeling, Optimization, and Synthesis for System-Level Analog and RF Designs

Abstract: The paper describes the recent state of the art in hierarchical analog synthesis, with a strong emphasis on associated techniques for computer-aided model generation and optimization. Over the past decade, analog design automation has progressed to the point where there are industrially useful and commercially available tools at the cell level-tools for analog components with 10-100 devices. Automated techniques for device sizing, for layout, and for basic statistical centering have been successfully deployed. However, successful component-level tools do not scale trivially to system-level applications. While a typical analog circuit may require only 100 devices, a typical system such as a phase-locked loop, data converter, or RF front-end might assemble a few hundred such circuits, and comprise 10 000 devices or more. And unlike purely digital systems, mixed-signal designs typically need to optimize dozens of competing continuous-valued performance specifications, which depend on the circuit designer's abilities to successfully exploit a range of nonlinear behaviors across levels of abstraction from devices to circuits to systems. For purposes of synthesis or verification, these designs are not tractable when considered "flat." These designs must be approached with hierarchical tools that deal with the system's intrinsic design hierarchy. This paper surveys recent advances in analog design tools that specifically deal with the hierarchical nature of practical analog and RF systems. We begin with a detailed survey of algorithmic techniques for automatically extracting a suitable nonlinear macromodel from a device-level circuit. Such techniques are critical to both verification and synthesis activities for complex systems. We then survey recent ideas in hierarchical synthesis for analog systems and focus in particular on numerical techniques for handling the large number of degrees of freedom in these designs and for exploring the space of performance tradeoffs early in the design process. Finally, we briefly touch on recent ideas for accommodating models of statistical manufacturing variations in these tools and flows

Embedded System Design : Embedded Systems Foundations of Cyber-Physical Systems

Abstract: Until the late 1980s, information processing was associated with large mainframe computers and huge tape drives. During the 1990s, this trend shifted toward information processing with personal computers, or PCs. The trend toward miniaturization continues and in the future the majority of information processing systems will be small mobile computers, many of which will be embedded into larger products and interfaced to the physical environment. Hence, these kinds of systems are called embedded systems. Embedded systems together with their physical environment are called cyber-physical systems. Examples include systems such as transportation and fabrication equipment. It is expected that the total market volume of embedded systems will be significantly larger than that of traditional information processing systems such as PCs and mainframes. Embedded systems share a number of common characteristics. For example, they must be dependable, efficient, meet real-time constraints and require customized user interfaces (instead of generic keyboard and mouse interfaces). Therefore, it makes sense to consider common principles of embedded system design.Embedded System Design starts with an introduction into the area and a survey of specification models and languages for embedded and cyber-physical systems. It provides a brief overview of hardware devices used for such systems and presents the essentials of system software for embedded systems, like real-time operating systems. The book also discusses evaluation and validation techniques for embedded systems. Furthermore, the book presents an overview of techniques for mapping applications to execution platforms. Due to the importance of resource efficiency, the book also contains a selected set of optimization techniques for embedded systems, including special compilation techniques. The book closes with a brief survey on testing.Embedded System Design can be used as a text book for courses on embedded systems and as a source which provides pointers to relevant material in the area for PhD students and teachers. It assumes a basic knowledge of information processing hardware and software. Courseware related to this book is available at http://ls12-www.cs.tu-dortmund.de/~marwedel.