Matching Items (6)
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
The crime of human trafficking has received increased national attention over the past decade. However, the subject of human trafficking is rarely mentioned in criminal justice and criminology curricula in colleges and universities. This study discusses findings from a review of listed courses in 100 criminology and criminal justice bachelor degree programs in colleges and universities in the United States. Implications for further research, including examining criminal justice education programs outside of academe, are discussed. The author advocates adding courses on human trafficking in criminology and criminal justice curricula and makes recommendations for undergraduate criminology and criminal justice education.
ContributorsZhilina, Tatyana (Author) / Stancliff, Michael (Thesis advisor) / Bernat, Francesc (Committee member) / Vaughan, Suzanne (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT Research has shown that the manner in which people are treated in their interactions with agents of the criminal justice system matters. People expect criminal justice officials to treat them fairly and with honesty and respect, which is the basis for procedural justice. When people are treated in a procedurally just and equitable manner they will view the system as legitimate and will be more likely to voluntarily comply and cooperate with legal system directives. People who have personal or vicarious experiences of unfair or unjust interactions with the legal system tend to view the system as less legitimate and are less likely to comply and cooperate when they have contact with representatives of the system. This study examines a random sample of 337 arrestees in Maricopa County, Arizona who have been interviewed as a part of the Arizona Arrestee Reporting Information Network. Descriptive statistics and regression analysis are used to examine views of the procedural justice experienced by arrestees during arrest, perceptions of police legitimacy by arrestees, voluntary compliance to the law, and voluntary cooperation with police. Results of the study show that perceptions of legitimacy work through procedural justice, and that procedurally just interactions with police mediate racial effects on views of legitimacy. Views of procedural justice and legitimacy increase cooperation. No variables in this study were significantly related to compliance.
ContributorsJorgensen, Cody (Author) / Ready, Justin (Thesis advisor) / White, Michael (Committee member) / Katz, 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
Cultivation theory states that consuming television cultivates a social reality in the real world which aligns with the reality present in television. When the television show CSI was released, researchers studied a form of cultivation stemming from the show titled the "CSI Effect." One of the components of the CSI Effect is the tendency of those who watch CSI to be more likely to overestimate the presence of forensic evidence present in a trial and place more trust in such evidence. In recent years, several true crime documentaries that examined controversial cases have been released. In a similar vein of research conducted on CSI, the current study examines true crime documentaries and their possible impacts on viewers’ judgments and beliefs about the criminal justice system. In the current study, participants were provided with a mock case and asked about their perceptions of the case along with their viewership habits. While overall true crime documentary viewership did not influence judgments of evidence manipulation or perceptions of police, findings point to viewership of the targeted documentaries being associated with feelings of mistrust towards the criminal justice system overall, while the lesser-viewed documentaries correlated with judgments of strength and responsibility of the defendant in the case. One possible explanation is that individual characteristics may serve as the driving factor in how individuals choose what to watch when the popularity of the show is not as well-known.
ContributorsDoughty, Kathryn A (Author) / Schweitzer, Nicholas J. (Thesis advisor) / Neal, Tess (Committee member) / Salerno, Jessica (Committee member) / Arizona State University (Publisher)
Created2018
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