digital compensation of dynamic acquisition errors at the front-end of ...

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apply the inverse nonlinear function to the digital output of the ADC in order to minimize its error over the desired frequency range. Conceptually, a nonlinear system with memory can be modeled with a Volterra series. However, the inverse Volterra series becomes very complex as the order of nonlinearity and memory in the system increases and it requires intensive computational power that is impractical even in today’s fine-line technology. Our proposed algorithm uses information about the sources of nonlinearity and judicious modeling to simplify the digital post processing scheme. The main sources of dynamic error at the front-end of ADCs are investigated and analyzed in order to find a compact model for frequency-dependent nonlinearities in this stage. This model is then used to build a nonlinear filter in the digital domain for compensating the nonlinearities. The coefficients of the filter are calibrated using training signals in the desired frequency region. The correction scheme can be effectively used for canceling nonlinearities across the whole input bandwidth of the ADC. Measurement results from applying the proposed method to a 14-bit commercially available ADC are presented at different frequency ranges. The experimental results show an improvement in SFDR of the ADC to more than 83 dB up to input frequencies of 470 MHz. Measurement results show that the algorithm is not very sensitive to temperature variations and is also applicable to any sub-sampling ADC that suffers from linearity degradation at high input frequencies. vi
Acknowledgments I wish to acknowledge the many people who made my life at Stanford an enriching and enjoyable experience. First, I would like to thank Professor Boris Murmann for supervising my doctoral research and for his generous support and guidance during my graduate career at Stanford. His great technical vision and continuous encouragement helped me a lot in conducting my research. Every single meeting I had with him motivated me to try new ideas and go one step forward in my research. I am very grateful to Professor Robert Dutton for accepting me into his research group in my first year at Stanford, and for being very understanding and supportive through the problems I had during the past few years at Stanford. I appreciate his patience and guidance during the time I was looking for an interesting Ph.D. project. He has always been a great mentor for me and I enjoyed all the conversations I had with him. I would like to extend my gratitude to Professor Bruce Wooley for serving as a member of my orals and reading committee and for his help and advice throughout my graduate studies at Stanford. I would also like to thank Professor Piero Pianetta who served as the chair of my orals committee. The financial support of Center for Integrated Systems, National Semiconductor and Texas Instruments is greatly appreciated. I am grateful to David Boisvert and Bumha Lee at NSC, and Martin Izzard and Marco Corsi at TI for providing the test chips for our measurements. I would like to thank current and previous members of Professor Murmann’s and Professor Dutton’s group for all the useful discussions I had with them and for their help and support in various aspects of my project. In particular, I would like to thank vii
Page 1 and 2: DIGITAL COMPENSATION OF DYNAMIC ACQ
Page 3: I certify that I have read this dis
Page 8 and 9: Dr. Echere Iroaga, Dr. Yangjin Oh,
Page 10 and 11: Table of Contents Abstract.........
Page 12 and 13: 4.3.3 Algorithm performance on diff
Page 14 and 15: List of Figures Figure 1.1: Block d
Page 16 and 17: Figure 3.1: Block diagram of ADC er
Page 18 and 19: Figure 4.4: Frequency spectrum of t
Page 21 and 22: Chapter 1 Introduction 1.1 Motivati
Page 23 and 24: Chapter 1: Introduction 3 cancel th
Page 25 and 26: Chapter 1: Introduction 5 to correc
Page 27 and 28: Chapter 2 Nonlinearity at the ADC
Page 29 and 30: Chapter 2: Nonlinearity at the ADC
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Chapter 3 Digital Correction of Dyn
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Chapter 3: Digital Correction of Dy
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Chapter 4 Experimental Results In t
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Chapter 4: Experimental Results 67
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Chapter 5 Impact of Substrate Noise
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Chapter 5: Impact of Substrate Nois
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Chapter 6 Conclusion 6.1 Summary IF
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Chapter 6: Conclusion 95 very sensi
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Chapter 6: Conclusion 97 the desire
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Appendix A TCAD Simulation of a Tra
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Appendix A: TCAD Simulation of Trac
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Appendix A: TCAD Simulation of Trac
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Appendix B Modeling Signal Derivati
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Appendix B: Modeling Signal Derivat
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Appendix C Coefficient Calibration
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Appendix C: Coefficient Calibration
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Bibliography [1] A.M.A. Ali et al.,
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Bibliography 115 [23] J. Kuo, R. Du
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Bibliography 117 [46] F. H. Irons,
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Bibliography 119 [68] B. Razavi, B.
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