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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
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
The following thesis tries to rescue the novels Sab and Dos mujeres, written by the XIX century writer Gertrudis Gómez de Avellaneda, from the hegemonic discourse offered by the contemporary critics. This is possible by comparing the Epistolar novel Tu amante ultrajada no puede ser tu amiga with the two novels analyzed. Also, this thesis examines the epistolary novel as a set of documents that creates a literary work on their own. That is to say, it studies how these letters, written to her lovers during the years 1839 to 1854, create an autobiographical fiction, a novel of the romantic period, and a character that makes a myth out of the writer and poet Gertrudis Gómez de Avellaneda.
ContributorsGarcia Varela, Indira Yadira Ariana (Author) / Volek, Emil (Thesis advisor) / Rosales, Jesus (Committee member) / Garcia-Fernandez, Carlos-Javier (Committee member) / Arizona State University (Publisher)
Created2016
Description
During the mid-1930s in Cuba, Ernest Hemingway befriended Cuban artist Antonio Gattorno (1904-1980) during Hemingway's most active period of Gulf Stream fishing trips. Their relationship soon transcended ocean sojourns, and the two exchanged letters, eight of which reside in the Hemingway Collection at the J.F.K. Library in Boston. Written between 1935 and 1937, the Hemingway-Gattorno correspondence showcases the relationship that came to fruition between the American writer and Cuban artist in the 1930s. It also presents a lens through which to examine the cultural contact that occurred between Americans and Cubans during a decade of great political, social, and economic exchange between the two nations. In addition, the Hemingway-Gattorno correspondence elucidates each country's tendency to romanticize the other before the Cuban Revolution and provides a template with which to examine current U.S.-Cuban relationships today. This thesis endeavors to first discuss the Hemingway-Gattorno relationship via a close examination of the correspondence that occurred between them. It then attests that the Hemingway-Gattorno correspondence exemplifies the transatlantic glamorization that characterized pre-revolutionary U.S.-Cuban relations. The thesis explores the replay of this act of romanticizing in real time, arguing that despite governmental injunctions since 1961, Americans and Cubans alike have continued to ingeniously find ways to communicate with one another in much the same way Hemingway and Gattorno did in the 1930s. One mechanism for doing so is remembering Ernest Hemingway's life in Cuba and the home he owned there, Finca Vigía, a performance of memory that often occurs through the conduits of either the Hemingway Archives in Boston or the Finca Vigía Museum in Cuba. American and Cuban longing for the cultural contact enjoyed by Hemingway and Gattorno is expressed and performed through a glorification of Hemingway and the Finca Vigía, despite the severance of diplomatic relations between the two countries in 1961. In addition, for Cubans in particular, Hemingway and the Finca Vigía present an opportunity to imagine the much more unified pre-revolutionary Cuba. Although certainly Hemingway and his home represent different realities for Cubans and Americans, in all, the thesis will show that citizens from both countries continue to find ways to create and imagine themselves in pre-revolutionary contexts like those embodied by Hemingway and Gattorno in the 1930s.
ContributorsDriscoll, Sarah (Author) / Horan, Elizabeth (Thesis advisor) / Sadowski-Smith, Claudia (Committee member) / Tobin, Beth (Committee member) / Arizona State University (Publisher)
Created2011
Description
Magic, divination, and obeah appear in some form in almost all of Jamaica’s near-continuous revolts from the time the British took the island in 1655 to the decades following the abolition of slavery in 1834. Although discussions of African diasporic spiritual systems were very much alive in the early modern centuries, the forms that emerged in early colonial Jamaica have received little scholarly treatment. This study is an attempt to inject culture into the story of African resistance to slavery and colonialism in Jamaica by reconceptualizing three major rebellions as cultural rather than military histories and by highlighting the role of magic and divination in the genesis of these freedom struggles. The First Maroon War, Tacky’s Revolt, and the 1823 Boxing Day Conspiracy illuminate a clear system of supernatural understanding that came to include a definite link to political resistance and rebellion. These understandings were recognized by enslaved or formerly enslaved Africans as well as the British in Jamaica and abroad. Some work must be done to delineate what European settlers were responding to as the idea of obeah—and how it was related to European ideas about witchcraft and illicit magic—from the ideas held among African peoples. This is especially significant following Tacky’s Revolt, when the first anti-obeah laws in the Caribbean made obeah an explicitly political action. Europeans were clearly wrapped up in the politics of obeah to a degree that did not concern Africans. However, Africans also used obeah as a crucial form of political resistance. Thus, these three cases allow both British and African ideas about obeah to be traced over a century to reinject a cultural history of African-derived spirituality into an otherwise political narrative.
ContributorsBussey, Max (Author) / Barnes, Andrew (Thesis advisor) / Alexander, Leslie (Committee member) / Usman, Aribidesi (Committee member) / Arizona State University (Publisher)
Created2021