Matching Items (7)
Filtering by
- 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
Researchers who have previously explored the relation of broad-based temperamental approach constructs, such as surgency/extraversion, exuberance, or behavioral approach sensitivity, to academic competence (AC) in early elementary school have often found conflicting results. Moreover, few researchers have examined the interaction between these approach reactivity constructs and effortful control (EC) in the prediction of AC. The goal of the current study was to examine the fine-tuned relations of different aspects of temperamental approach reactivity in early childhood (42 and 54 months; N=223), such as impulsivity, frustration, and positive affect, as well as EC, to AC during early elementary school (72 and 84 months). Examining the complex relations may clarify the literature using broad-based approach reactivity constructs. Temperament was observed in the laboratory when children were 54 months of age. Mothers and caregivers also reported on children's impulsivity at 42 and 54 months. School-related behavioral adjustment was reported by children, mothers, and teachers, and GPA was reported by teachers at 72 and 84 months. The results of the study indicated that positive affect, EC, and receptive language ability were the only unique direct predictors of school adjustment and/or GPA. Without EC in the model, only positive affect and vocabulary predicted AC. Frustration, positive affect, and impulsivity each interacted with EC to predict AC outcomes, such EC was only related to higher AC for children with high impulsivity or anger, or low positive affect. Additionally, positive affect and impulsivity interacted to predict GPA, such that impulsivity was positively related to GPA for children with high positive affect, but it was negatively, albeit nonsignificantly, associated with GPA for children with low positive affect. These results were found to be similar for boys and girls. Finding are discussed in terms of the developmental importance of early EC for academic competence for children who have high approach reactivity, as well as the interactive effects of dimensions of approach reactivity on academic achievement.
ContributorsVanSchyndel, Sarah (Author) / Eisenberg, Nancy (Thesis advisor) / Spinrad, Tracy L. (Committee member) / Valiente, Carlos (Committee member) / Arizona State University (Publisher)
Created2014
Description
This work analyzed the role of interpersonal problems in interaction with ethnicity to predict psychotherapy outcome. A total of 262 individuals, who underwent psychotherapy at a counseling training facility, completed the Outcome Questionnaire-45 (OQ-45) and the reduced version of the Inventory of Interpersonal Problems (IIP-32). This study posited the following research question: Is the magnitude of the effect of ethnicity on treatment outcome conditional on certain IP dimensions (dominance or affiliation)? The purpose of this research was to determine whether or not ethnicity, represented by 3 ethnic groups (Whites, Hispanics, and Asians), was related to treatment outcome, and if this relationship was moderated by two interpersonal distress dimensions: dominance and affiliation. The results of the hierarchical regression analyses indicated that ethnicity did not predict post-treatment outcome gain, and neither affiliation nor dominance was a moderator of the relationship between outcome and ethnicity.
ContributorsJimenez Arista, Laura E (Thesis advisor) / Tracey, Terence (Committee member) / Kinnier, Richard (Committee member) / Claiborn, Charles (Committee member) / Arizona State University (Publisher)
Created2011
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
This study investigated the relation between Sensory Processing Sensitivity (SPS) temperament and depression, and whether such a relation might be further influenced by the indirect effects of parenting environment and empathic personal distress. A moderated mediation model was proposed to explain the underlying relations among SPS, depression, parenting environment and empathic personal distress. That is, greater levels of SPS temperament might predict higher levels of empathic personal distress, which then leads to increasing likelihood of experiencing depression. Moreover, it was predicted that this mediation relation might be significantly stronger under a less positive parenting context. The present study recruited 661 participants from a U.S. university and implemented questionnaires in an online survey. There was a significant main effect of SPS temperament in predicting empathic personal distress and depression, such that the more sensitive individuals reported higher empathic personal distress and depression. There also was a significant main effect of parenting environment on depression, where more positive parenting was associated with less depression. Empathic personal distress was found to partially mediate the relation between SPS and depression. That is, the association between SPS and depression could be partially explained by empathic personal distress. However, parenting environment did not moderate the main effect of SPS temperament on depression, the main effect of SPS on empathic personal distress, or the mediation model.
ContributorsYang, Wenxi (Author) / Miller, Paul A. (Thesis advisor) / Hall, Deborah L. (Committee member) / Roberts, Nicole A. (Committee member) / Arizona State University (Publisher)
Created2019
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
Previous research used the context-free Big Five model of personality traits to predict social media behaviors. The perspective implicit in this research assumes that expression of the Big Five is free of situational context. This thesis challenges this assumption to address whether people express the same Big Five on social media as offline. In two studies, this thesis addressed three issues: (1) whether there are self-reported differences in the Big Five between social media/online and offline contexts, (2) whether a five-factor structure replicates in the offline and social media context reports, and (3) whether the predictive validity of the Big Five is the same between offline and social media contexts. College students (total N = 2102) reported their offline and social media Big Five. Main findings reveal that, first, all of the Big Five have lower expressions in social media/online than offline, except for those in the lowest quartile of offline trait expressions; possible explanations include regression towards the mean or the environmental impact of social media. Second, a similar factor structure appeared with openness, extraversion, and neuroticism items being the most robust between offline and social media contexts. However, some conscientiousness and agreeableness items did not apply across offline and social media contexts. Third, the Big Five had different predictive patterns of social media behaviors depending on the context. These findings inform that future research may better serve to specify the context of Big Five expression to understand social media behavior.
ContributorsBunker, Cameron James (Author) / Kwan, Virginia S. Y. (Thesis advisor) / Edwards, Michael C. (Committee member) / Kenrick, Douglas T. (Committee member) / Arizona State University (Publisher)
Created2020