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.

This paper presents a high-level synthesis tool for /spl Sigma//spl Delta/ modulators (/spl Sigma//spl Delta/Ms) that combines an accurate SIMULINK-based time-domain behavioral simulator with a statistical optimization core. Three different circuit techniques for the modulator implementation are considered: switched-capacitor, switched-current and continuous-time. The behavioral models of these circuits, that take into account the most critical limiting factors, have been incorporated into the SIMULINK environment by using S-function blocks, which drastically increase the computational efficiency. The precision of these models has been validated by electrical simulations using HSPICE and experimental measurements from several silicon prototypes. The combination of high accuracy, short CPU time and interoperability of different circuit models together with the efficiency of the optimization engine makes the proposed tool an advantageous alternative for /spl Sigma//spl Delta/M synthesis. The implementation on the well-known MATLAB/SIMULINK platform brings numerous advantages in terms of data manipulation, processing capabilities, flexibility and simulation with other electronic subsystems. Moreover, this is the first tool dealing with the synthesis of /spl Sigma//spl Delta/Ms using both discrete-time and continuous-time circuit techniques.

This paper presents an overview of emerging circuits and systems techniques which are at the forefront of the state of the art in ΔΣ modulators, pushing their performance forward and giving rise to new generations of data converters. Among others, those strategies involving the development of new applications and paradigms-like RF/GHz-range ΔΣ digitisation, digital-assisted embedded loop filters, time-to-digital conversion and hybrid ΔΣ/Nyquist-rate architectures-are discussed, as well as the implications and design challenges derived from their integration in deep nanometer CMOS technologies. The envisioned ΔΣ techniques are presented in a systematic way around the main analog building blocks embedded in a ΔΣ modulator, i.e., the loop filter and the quantizer. Analysing the trends in the design of these blocks allows us to offer perspectives on how ΔΣ converters will evolve in the next years.

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