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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
Prior research looking at procedural justice has largely focused on legal authorities, such as the police. There is a gap in the research regarding the influence of procedurally-just treatment of other criminal justice professionals, including 911 operators. These individuals are often the first contact citizens have when initiating police services, and it is likely that 911 operators set the stage for how police encounters with the public unfold. Using a factorial vignette design, this study tests the causal links between procedural injustice and several outcome measures, including cooperation, satisfaction, callback likelihood, and willingness to testify in court. Data from a university-based sample (n=488) were used to estimate a series of ordinal regression models. The results show that participants who received the injustice stimuli were generally less likely to report they would call 911 in the future, cooperate with the 911 operator if asked additional questions, cooperate with the police once they arrived on the scene, and had lower levels of satisfaction with the how the operator handled the call. These results were significant across two different scenarios (i.e., breaking and entering and traffic accident). Seriousness of the encounter also varied across these outcomes, but the magnitude of the effect was more modest. The results demonstrate the effect non-sworn personnel, such as 911 operators, can have on the outcome of police-citizen encounters.
ContributorsFlippin, Michaela R (Author) / Reisig, Michael D. (Thesis advisor) / Young, Jacob T.N. (Committee member) / Trinkner, Rick (Committee member) / Arizona State University (Publisher)
Created2018
Description
Procedural justice has become a widely researched topic in the criminological field with applicability to multiple arenas, including policing, corrections, and courts. Its main tenents suggest that through fair treatment, respectful dialogue and being given a proper voice, citizens will view their experiences with authority more justly. However, though the literature regarding procedural justice has grown immensely, it is still unclear whether certain characteristics of individuals, such as gender and mental health, play a role in their perceptions of procedural justice. Using secondary data originally collected for Rossman, Roman, Zweig, Rempel and Lindquist’s Multi-Adult Drug Court Evaluation (MADCE), an attempt is made to address the previously neglected association between procedural justice, gender, mental health and the added aspect of specialized drug court participation. Results suggest that both gender and mental health, namely depression, play a significant role in predicting procedural justice. Additionally, being a drug court participant was significantly related to higher levels of perceived procedural justice. Implications for theory, research, and policy are discussed.
ContributorsSomers, Logan J (Author) / Reisig, Kristy (Thesis advisor) / Telep, Cody (Committee member) / Wang, Xia (Committee member) / Arizona State University (Publisher)
Created2016
Description
ABSTRACT
Many studies testing the effects of procedural justice judgments rely on cross-sectional data. The shortcomings of such a strategy are clear and alternative methodologies are needed. Using a factorial vignette design, this study tests a variety of hypotheses derived from the process-based model of regulation, most of which involve the posited outcomes of procedural justice judgments during police-citizen encounters. This technique allows the researcher to manipulate police process during citizen encounters via hypothetical scenarios. Experimental stimuli are used as independent variables in the regression models. The results show that participants who were administered vignettes characterized by procedural injustice had lower levels of encounter satisfaction, decision acceptance, immediate compliance and greater expectations that police handle similar situations in the future differently relative to individuals who did not receive the negative stimulus. These effects are statistically significant across encounters involving traffic stops and noise complaints. As anticipated, the effect of procedural injustice often proved more salient regardless of whether participants were administered vignettes where they received a citation. Given the utility of the vignette design, future researchers are encouraged to apply the design to additional causal questions derived from the process-based model.
Many studies testing the effects of procedural justice judgments rely on cross-sectional data. The shortcomings of such a strategy are clear and alternative methodologies are needed. Using a factorial vignette design, this study tests a variety of hypotheses derived from the process-based model of regulation, most of which involve the posited outcomes of procedural justice judgments during police-citizen encounters. This technique allows the researcher to manipulate police process during citizen encounters via hypothetical scenarios. Experimental stimuli are used as independent variables in the regression models. The results show that participants who were administered vignettes characterized by procedural injustice had lower levels of encounter satisfaction, decision acceptance, immediate compliance and greater expectations that police handle similar situations in the future differently relative to individuals who did not receive the negative stimulus. These effects are statistically significant across encounters involving traffic stops and noise complaints. As anticipated, the effect of procedural injustice often proved more salient regardless of whether participants were administered vignettes where they received a citation. Given the utility of the vignette design, future researchers are encouraged to apply the design to additional causal questions derived from the process-based model.
ContributorsMays, Ryan D (Author) / Reisig, Michael D (Thesis advisor) / Holtfreter Reisig, Kristy (Committee member) / Telep, Cody W. (Committee member) / Arizona State University (Publisher)
Created2016
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