High-Performance Data Converters - Steensgaard

1 High-Performance data ConvertersbyJesper thesis submitted in partial fulfillment ofthe requirementments for the degreeThe Technical University of DenmarkDepartment of Information TechnologyDK-2800, Lyngby DenmarkJanuary 20, 1999(Revised March 8, 1999)c by Jesper Steensgaard -Madsen, 1999 Copyrightc by Jesper Steensgaard -Madsen, 1999 All rights reservedAbstractNovel techniques for multi-bit oversampled data conversion are described. State-of-the-art oversam-pled data Converters are analyzed, leading to the conclusion that their performance is limited mainlyby low-resolution signal representation. To increase the resolution, High-Performance , high -resolutioninternal D/A Converters are required.

2 Unit-element mismatch-shaping D/A Converters are analyzed, andthe concept of mismatch-shaping is generalized to include scaled-element D/A Converters . Several typesof scaled-element mismatch-shaping D/A Converters are proposed. Simulations show that, when imple-mented in a standard CMOS technology, they can be designed to yield 100 dB performance at 10 proposed scaled-element mismatch-shaping D/A Converters are well suited for use as the feedbackstage in oversampled delta-sigma quantizers. It is, however, not easy to make full use of their potential,because that requires a high -resolution loop quantizer which introduces only a small delay.

3 Generally, itis not acceptable to design the loop quantizer as a high -resolution flash quantizer because they require alarge chip area and high power consumption. Pipeline techniques are proposed to circumvent this prob-lem. This way, the delta-sigma quantizer s feedback signal is obtained by a multiple-stage quantization,where the loop quantizer (low-resolution and minimum-delay) implements only the last-stage quanti-zation. Hence, high -speed, high -resolution delta-sigma quantization is feasible without using improved version of the MASH topology is also proposed. A delta-sigma quantizer is used to quan-tize the input signal into an oversampled digital representation of low-to-moderate resolution.

4 The delta-iiisigma quantizer s truncation error is estimated either directly, or as the first-order difference of the outputsignal from the loop filter s first integrator stage. This technique avoids the need for accurate matchingof analog and digital filters that characterizes the MASH topology, and it preserves the signal-bandsuppression of quantization errors. Simulations show that quantizers of this type can yield 100 dB per-formance at 10 times oversampling. There are no requirements for high -resolution flash quantizers orother hard-to-implement author wishes to acknowledge several people for their contributions to this a category by himself, Professor Gabor C.

5 Temes has helped me in countless ways during the almosttwo years I have been fortunate enough to work with him. I thank him for his friendship, encouragement,advice, enthusiasm, ideas, feedback, editing, our discussions, and for providing an environment whereelectrical engineering can be practiced in a fun and rewarding way. He truly deserves the IEEE GraduateTeaching Award, which was awarded to him in 1998. He has my highest respect and appreciation inevery Oregon State University I have worked with many wonderful people with whom I have had fruitfuldiscussions. They have included Professor Un-Ku Moon, Professor Richard Schreier, Luis Hernandez,Andreas Wiesbauer, Paul Ferguson, Yunteng Huang, Bo Wang, Tao Sun, and many particularly wish to thank the President of MEAD Microelectronics Inc.

6 Of Switzerland, Vlado Valence,and Gabor and Ibi Temes, from MEAD, for inviting me to participate in the outstanding coursesin electrical engineering which they arrange in Switzerland and in the United States. I believe I haveobtained some of my most useful and practical information from these courses, and I am very gratefulfor that. I need to thank the outstanding course lecturers who teach these courses, many of whom I havebeen fortunate to encounter in private and fruitful discussions. In arbitrary order, I particularly wishto thank Bob Adams, Eric Vittoz, Paul Brokaw, Tim Schmerbeck, Christian Enz, Todd Brooks, PaulFerguson, Bob Blauschild, Ian Galton, Berrie Gilbert, Stephen Jantzi and several also extend my thanks to the design team at MEAD Microelectronics Inc.

7 , particularly Fabien andPhillip making my life pleasant in many ways, I wish to thank my brother, Bjarne, his wife, Tamara, andmy girlfriend, Patrice. Also, I wish to thank Ms. Ibi Temes for her gracious hospitality at the Temes home on several , I wish to thank my supervisor, Erik Bruun, and the Danish educational system for its Class of data Converters Structure of This Property Rights .. 72 Characterization of Representation of Signals .. Signals .. Representation of Signals .. Transformation of Continuous-Time Transformation of Discrete-Time Signals .. of the Signal Band.

8 S Sampling Theorem .. of a Signal s Fourier Based on a Finite-Duration Based on Assumed Discrete Fourier Transformation.. 233 Basic Aspects of data Steps in A/D Conversion .. Caused by the Anti-Aliasing Caused by the Sample-and-Hold Circuit .. of the Ideal Quantizer .. of Quantizer Errors .. Steps in D/A Conversion .. Voltage-Mode Implementation.. Current-Mode Implementation.. Jitter in D/A Converters .. performance of D/A Converters .. Dynamic performance .. Range .. Dynamic Range .. Distortion .. data Quantizers .. data Quantizers.

9 To Signal 714 State-of-the-Art Signal Delta-Sigma Quantizers .. and Preserving Topology .. of the MASH Delta-Sigma Quantizers .. Properties .. DACs .. of the Error Signal .. Unit-Element Mismatch-Shaping DACs .. of First-Order Mismatch-Shaping Mismatch-Shaping DACs .. of Second-Order Mismatch-Shaping DACs .. Encoders in Limitation .. Delta-Sigma Quantizers .. Delta-Sigma Current-Mode Return-to-Zero Current-Mode Current-Mode DAC .. Topology and Operation .. of Mismatch-Shaping Tones in Deterministic UE-MS Encoders .. Tones in ERS UE-MS Encoders.

10 Tones in Complex UE-MS UE-MS Encoders .. Tree-Structure UE-MS ERS UE-MS Dithered ERS Encoder .. Family of Dithering Dithering .. Mismatch-Shaping D/A Mismatch-Shaping Aspect of the Design of Mismatch-Shaping Unit-Element DACs Revisited .. Scaled-Element Mismatch-Shaping Encoders .. Scaled-Element Mismatch-Shaping Dual-Type-Element Mismatch-Shaping DAC .. the Delta-Sigma Modulator .. Work Scaled-Element Mismatch-Shaping DACs .. Tree Structures .. Tree-Structure .. Scaled-Element Mismatch-Shaping Scaled-Element Mismatch-Shaping Encoder .. Filtering Scaled-Element Mismatch-Shaping DACs.