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- Creators: Chakraborty, Bijeta
- Creators: Rogers, Rodney
- Member of: ASU Electronic Theses and Dissertations
- Status: Published
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
Despite the growth of technology in music composition and performance, professional clarinetists maintain that air microphones are superior to piezoelectric pickups. Pickups offer increased mobility, isolation, and reduced feedback, but air microphones are used simply for the perceived sound quality. In this study a ported barrel pickup and a contact transducer pickup placed at various intervals on the clarinet were sampled and compared to a reference recording to determine how the sound differed for each method. In addition, the history of wind instrument pickups, the acoustics of the clarinet, and the basics of piezoelectricity were discussed to help examine the results. The pickups were examined in three ways: overall level in decibels, frequency cutoff, and overtone displacement. Through these results it was determined that the most accurate methods of clarinet pickup are the ported barrel pickup, contact transducers closer to the vibration of the reed such as the ligature or barrel surface, or a transducer placed at the end of the bell. These findings were consistent with the discussions regarding history, clarinet acoustics, and piezoelectricity. This study also produced a reference for the sounds associated with different pickup methods, as well as possible improvements for clarinet pickup design.
ContributorsEnglert, Patrick William (Author) / Spring, Robert S (Thesis advisor) / Gardner, Joshua T (Thesis advisor) / Caslor, Jason (Committee member) / Rogers, Rodney (Committee member) / Arizona State University (Publisher)
Created2018