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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
The primary goal of this study was to extend previous research on traditional masculinity by examining the longitudinal associations between traditional masculinity, school engagement and attitudes toward school in a sample of middle school students. Following a sample of 338 (Mage = , SDage = , 54% male, 46% Latino) students from the 7th to 8th grades, I examined how students' self-reported endorsement of and adherence to physical toughness and emotional stoicism norms of masculinity were associated with their engagement with school and their attitudes of school liking and school avoidance. I also examined whether the endorsement and adherence to these norms varied by sex and ethnicity, and whether they changed over the one-year period. Results indicated that endorsing and adhering to masculinity norms of emotional stoicism were negatively associated with school engagement, after controlling for school engagement at Time 1. Furthermore, endorsing and adhering to masculinity norms of physical toughness were negatively associated with attitudes of school liking even when controlling for school liking at Time 1. These results were the same boys and girls, and for Latino and White adolescents. Moreover, results indicated sex, but no ethnicity differences in traditional masculinity, such that males generally reported higher levels of endorsement and adherence to norms of physical toughness and emotional stoicism. There were also identifiable developmental patterns in traditional masculinity over a one-year period. The contributions of these findings to the current scholarship on masculinity, along with their implications for future research and practice, are discussed.
ContributorsRogers, Adam A (Author) / Updegraff, Kimberly A. (Thesis advisor) / Martin, Carol L (Committee member) / Santos, Carlos E. (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
Description
Given the major investment young people make in earning and maintaining a peer reputation, our goal in this study was to explore the association between dimensions of negative and positive peer reputation in middle school and adjustment several years later, by the end of high school, among upper middle class youth. Prior research has shown negative reputations such as aggressive-disruptive and sensitive-isolated to be associated with maladjustment later in life, whereas reputations like popular and prosocial-leader have been related to positive future outcomes. However, there are contrary findings that reveal a more complex relationship between peer reputation and adjustment, showing certain “negative” reputations to be tied with better outcomes in some domains and the converse in others. Using a sample of middle school students, a confirmatory factor analysis (CFA) was performed to test a four-factor model of the Revised Class Play, a peer report measure on peer reputations. CFA findings supported the four-factor model with the following reputations: popular, prosocial, aggressive, and isolated. Structural equation models were used to predict 12th grade adjustment outcomes (academic achievement, psychopathology, substance use) from middle school peer reputation. Prosocial reputation in middle school was connected to higher academic achievement and fewer externalizing symptoms in 12th grade. Both prosocial and isolated peer reputation were negatively associated with alcohol, cigarette, and marijuana use, whereas a popular reputation was related to higher levels of alcohol use. Middle school reputation did not predict internalizing symptoms in 12th grade. Findings are discussed in terms of adaptive and maladaptive adjustment outcomes associated with each peer reputation and implications for future research.
ContributorsCurlee, Alexandria (Author) / Luthar, Suniya (Thesis advisor) / Aiken, Leona (Committee member) / Infurna, Frank (Committee member) / Arizona State University (Publisher)
Created2016
Description
The present study was designed to extend previous research on early adolescents' involvement in electronic aggression and victimization. A new measure for electronic victimization and aggression was created for this study in order to better assess this type of peer harassment in early adolescence. The first goal of the study was to describe young adolescents' involvement in electronic aggression and victimization by exploring the links between electronic victimization and aggression and (a) youth demographic characteristics (e.g., gender, ethnicity), (b) involvement in traditional forms of aggression and victimization, and (c) gender of the aggression/victimization context (i.e., same-sex aggressor -victim versus other-sex aggressor- victim dyad). The second goal was to examine how electronic victimization and aggression were associated with self-esteem and relationship efficacy. Participants were 826 (49.9% female) 7th and 8th grade students (M age = 12.5 years old; SD = .67). Students were administered surveys during school hours. Results indicated that girls were more likely to be involved in both electronic aggression and victimization than boys. Further, girls were more likely to be both electronic aggressors and victims simultaneously than boys. Finally, those involved with electronic aggression reported higher levels of relationship efficacy than their peers and involvement as an aggressor/victim was associated with lower self-esteem than any other involvement category.
ContributorsMartin, Melissa (Author) / Updegraff, Kimberly A (Thesis advisor) / Ladd, Becky (Committee member) / Martin, Carol (Committee member) / Arizona State University (Publisher)
Created2013
Description
ABSTRACT Cyberbullying has emerged as one of educators' and researchers' chief concerns as the use of computer mediated communication (CMC) has become ubiquitous among young people. Many undesirable outcomes have been identified as being linked to both traditional and cyberbullying, including depression,truancy, and suicide. America and Japan have both been identified as nations whose youth engage frequently in the use of CMC, and may be at a potentially higher risk to be involved in cyberbullying. Time spent using CMC has been linked to involvement in cyberbullying, and gender and age have, in turn, been linked to CMC use - these may play significant roles in determining who is at risk. In order to assess the effects of nationality, gender, and age on cyberbullying involvement among Japanese and American middle school students, a survey exploring these factors was developed and carried out with 590 American and Japanese middles school students (Japan: n = 433 and America: n = 157). MANOVA results indicated that that Americans tend to both use CMC more and be more involved in cyberbullying. In addition, Japanese involvement increased with age, while American involvement did not. There were minimal differences between Americans and Japanese with regards to traditional bullying.
ContributorsLerner, David (Author) / Nakagawa, Kathryn (Thesis advisor) / Caterino, Linda (Thesis advisor) / Ladd, Becky (Committee member) / Arizona State University (Publisher)
Created2011