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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
General Strain Theory (GST) posits that different types of strain lead to different types of negative emotions, some of which increase the likelihood of maladaptive coping. Much research on GST has focused on anger and depression. Far less attention has been directed toward other negative emotions, including anxiety and envy. The current study uses cross-sectional data from surveys administered to a university-based sample (N = 500) to address these voids and explore gender differences in the effects of strain and negative emotions in maladaptive coping. Results indicate that when gender differences existed in levels of strain and negative emotions, females experienced higher levels than males. Strain significantly predicted all four measures of negative emotions examined in this study. Finally, different negative emotions were found to have differing effects on different measures of maladaptive coping. Implications of this study for theory, future research, and policy are discussed.
ContributorsZuniga, Ana Rosa (Author) / Holtfreter, Kristy (Thesis advisor) / Reisig, Michael (Committee member) / Wang, Xia (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 relationship between stress and policing has long been established in literature. What is less clear, however, is what departments are doing to help officers deal with the stress that comes with the job. Looking at a small Southwestern police agency and using a modified version of Speilberger’s (1981) Police Stress Survey, the present study sought to examine stressors inherent to policing, as well as to identify departmental services that may be in place to help officers alleviate those stressors and whether or not police officers would choose to take part in the services that may be offered. The findings suggest that a shift in stress in policing is occurring with operational stressors being reported at higher levels than organizational stressors, contrary to previous research.
ContributorsPadilla, Kathleen (Author) / White, Michael (Thesis advisor) / Telep, Cody (Committee member) / Sweeten, Gary (Committee member) / Arizona State University (Publisher)
Created2016
Description
The link between victimization and offending is well established in the literature, yet an unexplored causal pathway within this relationship is concerned with why some individuals engage in maladaptive coping in response to victimization. In particular, those with low self-control may be attracted to problematic yet immediately gratifying forms of coping post-victimization (e.g., substance use), which may increase their likelihood of violent offending in the future. Using three waves of adolescent panel data from the Gang Resistance Education and Training (GREAT) program, this research examines: (1) whether individuals with low-self control are more likely to engage in substance use coping following violent victimization, and (2) whether victims with low self-control who engage in substance use coping are more likely to commit violent offenses in the future. The results from negative binomial regressions support these hypotheses, even after controlling for prior offending, peer influences, prior substance abuse, and other forms of offending. The implications for integrating general strain and self-control theories, as well as for our understanding of the victimization-offending overlap, are discussed.
ContributorsTuranovic, Jillian (Author) / Pratt, Travis C. (Thesis advisor) / Reisig, Michael D (Committee member) / Fornango, Robert J (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study tested hypotheses derived from general strain theory, including whether the disposition for crime (e.g., trait anger and low self-control) and prosocial
coping moderate the link between state-based negative emotions and maladaptive coping.
A 2x2 factorial vignette was embedded in a survey instrument and administered to a
university-based sample (N = 503). The results from the regression models support
different parts of general strain theory, such as the direct effect of strain on negative
emotions, the effect of negative emotions on aggressive coping, and the mediating effect
of negative emotions. Finally, the effect of some negative emotions on aggressive coping
were moderated by trait anger, low self-control, and prosocial coping. The findings of
this study support the argument that dispositions to maladaptive coping amplify the
effects of negative emotion and underscore the importance of establishing prosocial
coping resources.
Keywords: emotions, general strain theory, low self-control, maladaptive coping
ContributorsWood, Margaret Tynan (Author) / Reisig, Michael D. (Thesis advisor) / Young, Jacob T.N. (Committee member) / Telep, Cody W. (Committee member) / Arizona State University (Publisher)
Created2023