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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Creators: Peterson, Cory
- Member of: ASU Electronic Theses and Dissertations
Description
Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
La Santa Muerte is a folk saint depicted as a female Grim Reaper in Mexico and the Southwestern United States. The Grim Reaper, as an iconic representation of death, was derived from the Angel of Death found in pseudepigrapha and apocalyptic writings of Jewish and early Christian writers. The Angel of Death arose from images and practices in pre-Christian Europe and throughout the Mediterranean region. Images taken from Revelation were used to console the survivors of the Black Death in Western Europe and produced a material culture that taught the Christian notion of dying well. The combination of the scythe (used in the eschatological harvest), the black cowl (worn by medieval priests and monks officiating at funerals), and the skeleton (as the physical body of the deceased) are a series of apocalyptic Christian referents that form a metonymical composite referred to as the Grim Reaper.
In medieval Iberian Dances of Death, the Grim Reaper was depicted as female, an unyielding social leveler, and an important participant in the Last Judgment. Personalized Death became associated with healing, renewal, magic, and binding, as apocalyptic Christianity blended with the Christian cult of the saints and the Virgin Mary during the Reconquista and the colonization of Mesoamerica. Utilizing secondary historical sources, metonymy, and iconology this Master of Arts thesis posits that the La Santa Muerte image resulted from a long historical interaction of Greek, Roman, Jewish, Visogothic, Islamic, and Christian death imagery leading up to the colonization of Mesoamerica.
In medieval Iberian Dances of Death, the Grim Reaper was depicted as female, an unyielding social leveler, and an important participant in the Last Judgment. Personalized Death became associated with healing, renewal, magic, and binding, as apocalyptic Christianity blended with the Christian cult of the saints and the Virgin Mary during the Reconquista and the colonization of Mesoamerica. Utilizing secondary historical sources, metonymy, and iconology this Master of Arts thesis posits that the La Santa Muerte image resulted from a long historical interaction of Greek, Roman, Jewish, Visogothic, Islamic, and Christian death imagery leading up to the colonization of Mesoamerica.
ContributorsBreault, Eric (Author) / Astor-Aguilera, Miguel A (Thesis advisor) / Gereboff, Joel (Committee member) / Maupin, Jonathan (Committee member) / Arizona State University (Publisher)
Created2014
Description
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description
Sacred apocalyptic texts claim to foretell coming events, warning the faithful of some terrible fate that lies beyond the present. Such texts often derive their power from successfully recasting past events in such a way as they appear to be "predicted" by the text and thus take on additional meanings beyond the superficial. This ex eventu status allows apocalyptic texts to increase the credibility of their future predictions and connect emotionally with the reader by playing on present fears. The fifth-century Daoist apocalyptic text, the Scripture on the Cycles of Heaven and Earth (Tiandi yundu jing, 天地運度經), is no exception. This thesis examines the apocalyptic markers in the poetic sections of the text, attempting to develop a strategy for separating the generic imagery (both to Chinese texts and the apocalyptic literary genre as a whole) from the more significant recoverable references to contemporary events such as the fall of the Jin dynasty and the subsequent founding of the Liu-Song dynasty.
ContributorsBussio, Jennifer Jean (Author) / Bokenkamp, Stephen (Thesis advisor) / Chen, Huaiyu (Committee member) / Cutter, Robert J (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis examines perceptions of climate change in literature through the lens of the environmental humanities, an interdisciplinary field that brings history, ecocriticism, and anthropology together to consider the environmental past, present and future. The project began in Iceland, during the Svartárkot Culture-Nature Program called “Human Ecology and Culture at Lake Mývatn 1700-2000: Dimensions of Environmental and Cultural Change”. Over the course of 10 days, director of the program, Viðar Hreinsson, an acclaimed literary and Icelandic Saga scholar, brought in researchers from different fields of study in Iceland to give students a holistically academic approach to their own environmental research. In this thesis, texts under consideration include the Icelandic Sagas, My Antonia by Willa Cather, Tropic of Orange by Karen Tei Yamashita, and The Water Knife by Paolo Bacigalupi. The thesis is supported by secondary works written by environmental humanists, including Andrew Ross, Steve Hartman, Ignacio Sanchez Cohen, and Joni Adamson, who specialize in archeological research on heritage sites in Iceland and/or study global weather patterns, prairie ecologies in the American Midwest, the history of water in the Southwest, and climate fiction. Chapter One, focusing on the Icelandic Sagas and My Antonia, argues that literature from different centuries, different cultures, and different parts of the world offers evidence that humans have been driving environmental degradation at the regional and planetary scales since at least the 1500s, especially as they have engaged in aggressive forms of settlement and colonization. Chapter Two, focused on Tropic of Orange, this argues that global environmental change leads to extreme weather and drought that is increasing climate migration from the Global South to the Global North. Chapter Three, focused on The Water Knife, argues that climate fiction gives readers the opportunity to think about and better prepare for a viable and sustainable future rather than wait for inevitable apocalypse. By exploring literature that depicts and represents climate change through time, environmental humanists have innovated new methods of analysis for teaching and thinking about what humans must understand about their impacts on ecosystems so that we can better prepare for the future.
ContributorsBurns, Kate S (Author) / Adamson, Joni (Thesis advisor) / Lussier, Mark (Committee member) / Sadowski-Smith, Claudia (Committee member) / Arizona State University (Publisher)
Created2019