Bandpass Sigma Delta Modulators

Bandpass Sigma Delta Modulators
Author: Jurgen van Engelen
Publisher: Springer Science & Business Media
Total Pages: 190
Release: 2013-03-09
Genre: Technology & Engineering
ISBN: 1475745869

Sigma delta modulation has become a very useful and widely applied technique for high performance Analog-to-Digital (A/D) conversion of narrow band signals. Through the use of oversampling and negative feedback, the quantization errors of a coarse quantizer are suppressed in a narrow signal band in the output of the modulator. Bandpass sigma delta modulation is well suited for A/D conversion of narrow band signals modulated on a carrier, as occurs in communication systems such as AM/FM receivers and mobile phones. Due to the nonlinearity of the quantizer in the feedback loop, a sigma delta modulator may exhibit input signal dependent stability properties. The same combination of the nonlinearity and the feedback loop complicates the stability analysis. In Bandpass Sigma Delta Modulators, the describing function method is used to analyze the stability of the sigma delta modulator. The linear gain model commonly used for the quantizer fails to predict small signal stability properties and idle patterns accurately. In Bandpass Sigma Delta Modulators an improved model for the quantizer is introduced, extending the linear gain model with a phase shift. Analysis shows that the phase shift of a sampled quantizer is in fact a phase uncertainty. Stability analysis of sigma delta modulators using the extended model allows accurate prediction of idle patterns and calculation of small-signal stability boundaries for loop filter parameters. A simplified rule of thumb is derived and applied to bandpass sigma delta modulators. The stability properties have a considerable impact on the design of single-loop, one-bit, high-order continuous-time bandpass sigma delta modulators. The continuous-time bandpass loop filter structure should have sufficient degrees of freedom to implement the desired (small-signal stable) sigma delta modulator behavior. Bandpass Sigma Delta Modulators will be of interest to practicing engineers and researchers in the areas of mixed-signal and analog integrated circuit design.

Systematic Design of CMOS Switched-Current Bandpass Sigma-Delta Modulators for Digital Communication Chips

Systematic Design of CMOS Switched-Current Bandpass Sigma-Delta Modulators for Digital Communication Chips
Author: José M. de la Rosa
Publisher: Springer Science & Business Media
Total Pages: 478
Release: 2007-05-08
Genre: Technology & Engineering
ISBN: 0306481944

This very detailed book discusses architectures, circuits and procedures for the optimum design of bandpass sigma-delta A/D interfaces for mixed-signal chips in standard CMOS technologies. It provides uniquely in-depth coverage of switched-current errors, which supports the design of high performance SI chips.

Delta-Sigma Modulators

Delta-Sigma Modulators
Author: George I Bourdopoulos
Publisher: World Scientific
Total Pages: 259
Release: 2003
Genre: Technology & Engineering
ISBN: 1860943691

This important book deals with the modeling and design of higher-order single-stage delta-sigma modulators. It provides an overview of the architectures, the quantizer models, the design techniques and the implementation issues encountered in the study of the delta-sigma modulators. A number of applications are discussed, with emphasis on use in the design of analog-to-digital converters and in frequency synthesis. The book is education- rather than research-oriented, containing numerical examples and unsolved problems. It is aimed at introducing the final-year undergraduate, the graduate student or the electronic engineer to this field.

Delta-Sigma Data Converters

Delta-Sigma Data Converters
Author: Steven R. Norsworthy
Publisher: Wiley-IEEE Press
Total Pages: 522
Release: 1997
Genre: Technology & Engineering
ISBN:

This comprehensive guide offers a detailed treatment of the analysis, design, simulation and testing of the full range of today's leading delta-sigma data converters. Written by professionals experienced in all practical aspects of delta-sigma modulator design, Delta-Sigma Data Converters provides comprehensive coverage of low and high-order single-bit, bandpass, continuous-time, multi-stage modulators as well as advanced topics, including idle-channel tones, stability, decimation and interpolation filter design, and simulation.

Sigma-Delta Converters: Practical Design Guide

Sigma-Delta Converters: Practical Design Guide
Author: Jose M. de la Rosa
Publisher: John Wiley & Sons
Total Pages: 581
Release: 2018-11-05
Genre: Technology & Engineering
ISBN: 1119275784

Thoroughly revised and expanded to help readers systematically increase their knowledge and insight about Sigma-Delta Modulators Sigma-Delta Modulators (SDMs) have become one of the best choices for the implementation of analog/digital interfaces of electronic systems integrated in CMOS technologies. Compared to other kinds of Analog-to-Digital Converters (ADCs), Σ∆Ms cover one of the widest conversion regions of the resolution-versus-bandwidth plane, being the most efficient solution to digitize signals in an increasingly number of applications, which span from high-resolution low-bandwidth digital audio, sensor interfaces, and instrumentation, to ultra-low power biomedical systems and medium-resolution broadband wireless communications. Following the spirit of its first edition, Sigma-Delta Converters: Practical Design Guide, 2nd Edition takes a comprehensive look at SDMs, their diverse types of architectures, circuit techniques, analysis synthesis methods, and CAD tools, as well as their practical design considerations. It compiles and updates the current research reported on the topic, and explains the multiple trade-offs involved in the whole design flow of Sigma-Delta Modulators—from specifications to chip implementation and characterization. The book follows a top-down approach in order to provide readers with the necessary understanding about recent advances, trends, and challenges in state-of-the-art Σ∆Ms. It makes more emphasis on two key points, which were not treated so deeply in the first edition: It includes a more detailed explanation of Σ∆Ms implemented using Continuous-Time (CT) circuits, going from system-level synthesis to practical circuit limitations. It provides more practical case studies and applications, as well as a deeper description of the synthesis methodologies and CAD tools employed in the design of Σ∆ converters. Sigma-Delta Converters: Practical Design Guide, 2nd Edition serves as an excellent textbook for undergraduate and graduate students in electrical engineering as well as design engineers working on SD data-converters, who are looking for a uniform and self-contained reference in this hot topic. With this goal in mind, and based on the feedback received from readers, the contents have been revised and structured to make this new edition a unique monograph written in a didactical, pedagogical, and intuitive style.

Design of a 125 Mhz Tunable Continuous-time Bandpass [sigma Delta] Modulator for Wireless IF Applications

Design of a 125 Mhz Tunable Continuous-time Bandpass [sigma Delta] Modulator for Wireless IF Applications
Author: Xuemei Liu
Publisher:
Total Pages:
Release: 2006
Genre:
ISBN:

Bandpass sigma-delta modulators combine oversampling and noise shaping to get very high resolution in a limited bandwidth. They are widely used in applications that require narrowband high-resolution conversion at high frequencies. In recent years interests have been seen in wireless system and software radio using sigma-delta modulators to digitize signals near the front end of radio receivers. Such applications necessitate clocking the modulators at a high frequency (MHz or above). Therefore a loop filter is required in continuous-time circuits (e.g., using transconductors and integrators) rather than discrete-time circuits (e.g., using switched capacitors) where the maximum clocking rate is limited by the bandwidth of Opamp, switch's speed and settling-time of the circuitry. In this work, the design of a CMOS fourth-order bandpass sigma-delta modulator clocking at 500 MHz for direct conversion of narrowband signals at 125 MHz is presented. A new calibration scheme is proposed for the best signal-to-noise-distortion-ratio (SNDR) of the modulator. The continuous-time loop filter is based on Gm-C resonators. A novel transconductance amplifier has been developed with high linearity at high frequency. Q-factor of filter is enhanced by tunable negative impedance which cancels the finite output impendence of OTA. The fourth-order modulator is implemented using 0.35 mm triple-metal standard analog CMOS technology. Postlayout simulation in CADENCE demonstrates that the modulator achieves a SNDR of 50 dB (~8 bit) performance over a 1MHz bandwidth. The modulator's power consumption is 302 mW from supply power of " 1.65V.