Tang, Xian. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

This thesis proposes a novel fully digital technique for the estimation and correction of the DAC error in multi-bit delta sigma ADCs. The structure of the DAC error is indicated through a simple model for unit-element based DACs. The impact of the DAC error on the performance of ADC is then analyzed. Various techniques dealing with the DAC error are described and their drawbacks are pointed out. Based on the nature of the DAC error and the surrounding signals, a fully digital method to estimate the error from the ADC output and remove it is proposed. Simulation results are shown to support the effectiveness of the method. Simulations also show that the proposed technique can work together with the technique of adaptive compensation for quantization noise leakage in cascaded delta sigma (MASH) ADC cases. These two techniques are the foundation for the design of high speed, high resolution delta sigma ADCs with relaxed requirements on the analog circuits. To verify the proposed technique, an experimental MASH ADC was built, including the design and fabrication of a chip of a second-order multi-bit delta sigma ADC in a 1.6��m CMOS technology. The measured results show that the proposed DAC correction technique is highly effective. / Graduation date: 2004

Delta-sigma modulators are currently a very popular technique for making high-resolution analog-to-digital and digital-to-analog converters (ADCs and DACs). Most delta-sigma modulators in production today employ single-bit quantization because a 1-bit DAC is inherently linear, whereas a multi-bit DAC is not. Were it not for this drawback, the use of multi-bit quantization would improve a delta-sigma modulator's performance by increasing the modulator's resolution or increasing the modulators's bandwidth, while at the same time whitening the quantization noise and improving modulator stability. This thesis explores the element-mismatch-shaping technique, which attenuates the noise caused by static element mismatch in a multi-level DAC by a method similar to delta-sigma modulation. Existing element-matching techniques are reviewed and some analytical and architectural work related to the realization of mismatch-shaping logic is presented. A custom switched-capacitor (SC) DAC is used to verify various element mismatch-shaping algorithms. Experiments show that mismatch-shaping can reduce harmonic distortion by up to 30 dB. / Graduation date: 1998

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, 2010. / Printout. Includes bibliographical references (leaves 74-75). Also available on the World Wide Web.

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Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

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

Thesis (Ph. D.)--Carleton University, 1999. / Also available in electronic format on the Internet.