Bandpass Sigma Delta Modulators

Stability Analysis, Performance and Design Aspects
2000
ISBN: 978-0-7923-8698-8
Verlag: Springer US

Buch, Englisch, 188 Seiten, HC runder Rücken kaschiert, Format (B × H): 160 mm x 241 mm, Gewicht: 1050 g

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 , 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 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.
will be of interest to practicing engineers and researchers in the areas of mixed-signal and analog integrated circuit design.

Zielgruppe

Research

Autoren/Hrsg.

Plassche, Rudy J. Van De

Engelen, Jurgen van

Fachgebiete

• Technische Wissenschaften Technik Allgemein Konstruktionslehre und -technik
• Geisteswissenschaften Design Produktdesign, Industriedesign
• Mathematik | Informatik EDV | Informatik Angewandte Informatik Computeranwendungen in Wissenschaft & Technologie
• Technische Wissenschaften Elektronik | Nachrichtentechnik Elektronik Bauelemente, Schaltkreise
• Technische Wissenschaften Technik Allgemein Computeranwendungen in der Technik
• Technische Wissenschaften Elektronik | Nachrichtentechnik Elektronik Mikroprozessoren
• Mathematik | Informatik EDV | Informatik Professionelle Anwendung Computer-Aided Design (CAD)

Inhaltsverzeichnis

1 Introduction.- 2 Quantization and Sampling.- 3 Noise Shaping Concepts.- 4 Performance.- 5 Stability.- 6 Design of Continuous time Bandpass SDMs.- 7 SDM Implementations.- 8 Conclusion and Discussion.- References.- List of Acronyms.- List of Symbols.- A Modulator Response to Input Signals.- B Root Locus Search Method.- C Algorithm for Finding a Stability Boundary.- D Example VHDL description of a digital SDM.- About the Authors.