Matching Items (6)
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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
This paper primarily focuses on the Hopi Tribe of northeastern Arizona and how historical events shaped the current perception and applications of educational systems on the Hopi reservation. This thesis emphasizes the importance of understanding historical contexts of a community in order to understand the current predicament and to devise solutions to contemporary issues in which I primarily focus on education. Education is broken down in regards to the Hopi communities by history, how this history has affected those communities, ideas of sovereignty and power within education and then future probable solutions to integrating language and culture into Hopi schools.
This research is primarily literature and educational reports on the Hopi Tribe and other American Indian communities. The research was then compiled to find commonalities with other Indian communities to depict barriers to educational success as well as effects of western education such as traditional culture and language decline. Solutions and results that other Indian communities had devised were also researched to determine if they could be incorporated into the Hopi educational system and if they supported the language and culture that the Hopi people are trying to retain.
This research is primarily literature and educational reports on the Hopi Tribe and other American Indian communities. The research was then compiled to find commonalities with other Indian communities to depict barriers to educational success as well as effects of western education such as traditional culture and language decline. Solutions and results that other Indian communities had devised were also researched to determine if they could be incorporated into the Hopi educational system and if they supported the language and culture that the Hopi people are trying to retain.
ContributorsHongeva, Justin (Author) / Killsback, Leo (Thesis advisor) / Tippeconnic, John (Committee member) / Romero-Little, Mary Eunice (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
The following study is about the importance of including global art and art history in a bilingual/bicultural art classroom. The study was performed with twelve Navajo art students in a predominately Navajo high school located in a small urban town off the Navajo Reservation. Navajo students selected traditional and contemporary artworks they were curious to learn more about from four global cultures, familiar (Navajo and European) and unfamiliar (Maori and Benin). They also responded to art criticism questions and identified reasons they were curious about the artworks they selected. Students were curious about familiar (Navajo and European) artworks more than unfamiliar artworks (Maori and Benin). Of all student responses, 69% focused on the artwork selected; 16% focused on meaning and expression, and 15% focused on the artist. This study concludes by suggesting that there should be a middle ground about what to teach to Navajo children. I suggest that art education should include other cultural information within the Navajo philosophy of education.
ContributorsBegody, Chrystalee (Author) / Erickson, Mary (Thesis advisor) / Young, Bernard (Committee member) / Stokrocki, Mary (Committee member) / Arizona State University (Publisher)
Created2015
Description
In 2005 the Navajo Nation Tribal Council passed the Navajo Sovereignty in Education Act (NSEA). The NSEA has been herald as a decisive new direction in Diné education with implications for Diné language and cultural revitalization. However, research has assumed the NSEA will lead to decolonizing efforts such as language revitalization and has yet to critically analyze how the NSEA is decolonizing or maintains settler colonial educational structures. In order to critically investigate the NSEA this thesis develops a framework of educational elimination through a literature review on the history of United States settler colonial elimination of Indigeneity through schooling and a framework of decolonizing education through a review of literature on promising practices in Indigenous education and culturally responsive schooling. The NSEA is analyzed through the decolonizing education framework and educational elimination framework. I argue the NSEA provides potential leverage for both decolonizing educational practices and the continuation of educational elimination.
ContributorsPreston, Waquin (Author) / Vicenti Carpio, Myla (Thesis advisor) / Sumida Huaman, Elizabeth (Committee member) / Tippeconnic III, John (Committee member) / Arizona State University (Publisher)
Created2015
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