Delta-sigma modulators are currently a very popular technique for making high-resolution analog-to-digital and digital-to-analog converters. These oversampled data converters have several advantages over conventional Nyquist-rate converters, including an insensitivity to many analog component imperfections, a simpler antialiasing filter and reduced accuracy requirements in the sample and hold. Though the initial uses of delta-sigma modulators were in the audio field, the development of bandpass modulators opened up the application range to radar systems, digital communication systems and instruments which convert IF, or even RF, analog signals directly to digital form. This thesis presents a method used to analyze and synthesize continuous-time delta-sigma modulators for given specifications. A fourth-order prototype continuous-time bandpass delta-sigma modulator employing g[subscript m]-LC resonator structure is demonstrated on a PCB board and measurement results corroborate the theory. To allow the construction of very high performance delta-sigma modulators, this thesis presents an architecture for a multibit DAC constructed from unit elements which shapes element mismatches. Theoretical analysis and simulation shows that this architecture greatly increases the noise attenuation in the band-of-interest and facilitates the use of multibit quantization in delta-sigma modulators. The methods presented in this thesis will allow high-frequency wideband bandpass delta-sigma modulators to be constructed. / Graduation date: 1996

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 106-110). Also available on the World Wide Web.

With the progress of microfabrication and nanofabrication technologies, there has been a reawakened interest in the possibility of controlling the propagation of light in various materials periodically structured at a scale comparable to, or slightly smaller than the wavelength. We can now engineer materials with periodic structures to implement a great variety of optical phenomena. These include well known effects, such as dispersing a variety of wavelength to form a spectrum and diffracting light and controlling its propagation directions, to new ones such as prohibiting the propagation of light in certain directions at certain wavelengths and localizing light with defects in some artificially synthesized dielectric materials. Advances in this field have had tremendous impact on modern optical and photonic technologies. This doctoral research was aimed at investigating some of the physics and applications of periodic structures for building blocks of the optical communication and interconnection system. Particular research emphasis was placed on the exploitation of innovative periodic structure-based optical and photonic devices featuring better functionality, higher performance, more compact size, and easier fabrication. Research topics extended from one-dimensional periodic-structure-based true-time delay module, to two-dimensional periodic-structure-based silicon photonic-crystal electro-optic modulators. This research was specifically targeted to seek novel and effective solutions to some long-standing technical problems, such as slow switching speed, large device size, and high power consumption of silicon optical modulators, among others. For each subtopic, research challenges were presented and followed by the proposed solutions with extensive theoretical analysis. The proposals were then verified by experimental implementations. Experimental results were carefully interpreted and the future improvements were also discussed. / text

As high precision data acquisition systems continue to improve their performance and power efficiency to migrate into portable devices, increasing demands are placed on the performance and power efficiency of the analog-to-digital conversion modulator. On the other hand, analog-to-digital modulator performance is largely limited by several major noise sources including thermal noise, flicker noise, quantization noise leakage and internal analog and digital coupling noise. Large power consumption and die area are normally required to suppress the above noise energies, which are the major challenges to achieve power efficiency and cost targets for modern day high precision converter design. The main goal of this work is to study various approaches and then propose and validate the most suitable topology to achieve the desired performance and power efficiency specifications, up to 100 kHz bandwidth with 16-21 bits of resolution. This work will first study various analog-to-digital conversion architectures ranging from Nyquist converters such as flash, pipeline, to the delta sigma architecture. Advantages and limitations of each approach will be compared to develop the criteria for the optimal modulator architecture. Second, this work will study analog sub-circuit blocks such as opamp, comparator and reference voltage generator, to compare the advantages and limitations of various design approaches to develop the criteria for the optimal analog sub circuit design. Third, this work will study noise contributions from various sources such as thermal noise, flicker noise and coupling noise, to explore alternative power and die area efficient approaches to suppress the noise. Finally, a new topology will be proposed to meet all above criteria and adopt the new noise suppression concepts, and will be demonstrated to be the optimal approach. The main difference between this work from previous ones is that current work places emphasis on the integration of the modulator architecture design and analog sub-circuit block research efforts. A high performance stereo analog-to-digital modulator is designed based on the new approach and manufactured in silicon. The chip is measured in the lab and the measurement results reported in the dissertation. / text

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Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 65-68). Also available on the World Wide Web.

Thesis (M.S.)--Ohio University, November, 1997. / Title from PDF t.p.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph.D.) - Carleton University, 2007. / Includes bibliographical references (p. 111-116). Also available in electronic format on the Internet.