Matching Items (8)
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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- 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
A model of the effects of early adolescents' temperament (negative emotionality and inhibitory control) and threat appraisals on resulting status in the bullying dynamic was examined. Specifically, I examined the hypothesis that negative emotionality and passive victim versus bully-victim status would be mediated by threat appraisals, and that mediated effect would be moderated by levels of inhibitory control. The study used a sample of 56 early adolescents ages 7–16. Temperament characteristics were measured using the EATQ–R (Capaldi & Rothbart, 1992). Threat appraisals were assessed using items from Hunter, Boyle, and Warden (2004). Bullying and victimization were measured using items created for this study and additional cyber bullying items (Smith, Mahdavi, Carvalho, & Tippett, 2006). A multinomial logistic regression and test of moderated mediation were analyzed to examine the model (Hayes, 2012). Higher levels of negative emotionality were correlated with being a victim of bullying. The moderated mediation model was not statistically significant, however the direction of the patterns fit the hypotheses. Future directions and limitations are discussed.
ContributorsMintert, Jeffrey (Author) / Miller, Paul A. (Thesis advisor) / Roberts, Nicole A. (Committee member) / Newman, Matt L (Committee member) / Arizona State University (Publisher)
Created2012
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 moderating effects of five characteristics of peers--their effortful control, anger, sadness, aggression, and positive peer behavior--were investigated in two separate series of analyses of preschooler's social behavior: (a) the relation between children's own effortful control and social behavior, and (b) the relation between children's shyness and reticent behavior. Latent variable interactions were conducted in a structural equation framework. Peer context anger and effortful control, albeit with unexpected results, interacted with children's own characteristics to predict their behavior in both the EC and shy model series; these were the only significant interactions obtained for the EC model series. The relation between shyness and reticent behavior, however, showed the greatest impact of peer context and, conversely, the greatest susceptibility to environmental variations; significant interactions were obtained in all five models, despite the limited range of peer context sadness and aggression observed in this study.
ContributorsHuerta, Snježana (Author) / Eisenberg, Nancy (Thesis advisor) / Spinrad, Tracy (Committee member) / Pina, Armando (Committee member) / Geiser, Christian (Committee member) / Arizona State University (Publisher)
Created2012
Description
This longitudinal study examined the relations between self-regulation and reading achievement from kindergarten through second grade. In addition to the broader concept of effortful control, this study looked at various sub-components, including attention focusing and inhibitory control. A series of unconditional latent growth curve models were estimated to assess the initial level and growth of children’s parent- and teacher-reported effortful control and reading skills. In addition, parallel-process latent-growth curve models were estimated to examine the relations between the growth parameters (e.g., how the initial level and growth in self-regulation relates to the initial level and growth in reading). Parent-reported inhibitory control and effortful control displayed linear growth over this time period. Teacher-reported self-regulation did not change significantly. Reading achievement increased across all three time points, but the rate of growth was steeper from kindergarten through first grade than from first to second grade. Results from the parallel-process models showed that the kindergarten scores for parent-reported attention focusing and inhibitory control were negatively related to growth in Letter Word abilities from first through second grade, whereas initial teacher-reported attention focusing, inhibitory control, and effortful control were negatively related to growth in Passage Comprehension abilities from first to second grade. This study illustrates important relations between self-regulation and reading abilities throughout the first few years of elementary school.
ContributorsWall, Carla (Author) / Valiente, Carlos (Thesis advisor) / Jahromi, Laudan (Committee member) / Thompson, Marilyn (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
The following study evaluated the effectiveness of a self-monitoring strategy on independent work behavior. The three subjects were in first grade, seven years old, identified with mild mental retardation (MIMR), and had an Individualized Education Plan (IEP) with targeted functional academic and behavior goals. The purpose of this study was to investigate the effect of a self-monitoring strategy on on-task independent work behavior and task completion. The research sought to determine whether or not a self-monitoring strategy would affect on-task independent work behavior and task completion. A multiple baseline across subjects design was used. Data were collected using a frequency count of off-task behavior. The self-monitoring strategy was found to be successful with all three subjects in the study. Overall, the subjects demonstrated a decrease in off-task behavior during independent work time after the intervention was introduced.
ContributorsCoughlin, Jennifer (Author) / McCoy, Kathleen (Thesis advisor) / Kenzer, Amy (Committee member) / Mathur, Sarup (Committee member) / Zucker, Stanley (Committee member) / Arizona State University (Publisher)
Created2010
Description
The present study examined the relations of children's effortful control (EC), emotion understanding, maladjustment, social competence, and relationship quality with nonparental caregivers in a sample of 30-, 42-, and 54-month olds. EC was measured with mothers' and caregivers' reports, as well as observed behavioral tasks. Emotion understanding was assessed by asking children to identify emotions during a puppet task. Mothers and caregivers also reported on children's problem behaviors and social competence. Caregivers provided reports of the quality of their relationship with children. Results from longitudinal structural equation models indicated that even after controlling for sex, SES, language ability, and previous levels of constructs, emotion understanding predicted EC one year later at 42 and 54 months. In addition, children with higher EC had more positive relationships with caregivers at 42 and 54 months. Although EC and EU were not significantly related to maladjustment and social competence after accounting for within time covariation among constructs and longitudinal stability, marginal findings were in expected directions and suggested that more regulated children with better emotion understanding skills had fewer behavioral problems and were more socially skilled. Findings are discussed in terms of the strengths and limitations of the present study.
ContributorsSilva, Kassondra M (Author) / Spinrad, Tracy L. (Thesis advisor) / Eisenberg, Nancy (Committee member) / Valiente, Carlos (Committee member) / Arizona State University (Publisher)
Created2012