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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
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 goal of this study was to examine the correlation between the brain's preconscious processing of relationship events and direct observation of couples' behavior during a videotaped discussion task. Although we know about the interaction dynamics within romantic relationships that portend conflict and dissatisfaction, very little is known about how individuals read interpersonal events within their relationship. Romantic partners participated in a dyadic EEG (electroencephalogram) lab session in which they played a gambling task. The gambling task consisted of three conditions: 1) individual gambling 2) watching their partners gamble and 3) gambling with advice from their partners. Following the gambling tasks, partners were videotaped discussing relationship topics. Neurocognitive reactions to winning and losing a gamble in response to partner's advice were analyzed as an Evoked Response Potential (ERP). The ERP of interest was the P300, which is associated with the brain making sense of unexpected information. Using an actor partner framework, it was found that the females' P300 predicted observed coercive interaction patterns. This finding suggests that for females with an established coercive relationship with their male partners, positive feedback was unexpected compared to losing.
ContributorsChampion, Charlie (Author) / Dishion, Thomas (Thesis advisor) / Ha, Thao (Committee member) / Randall, Ashley (Committee member) / Arizona State University (Publisher)
Created2016
Description
Stress in romantic relationships is an all-too-common phenomenon that has detrimental effects on relationship well-being. Specifically, stress can increase partners’ negative interactions, ultimately decreasing effective communication and overall relationship functioning. Positive dyadic coping (DC) occurs when one partner assists the other in coping with stress (e.g. empathizing or helping the partner problem-solve solutions to their stress), and has been proposed as a method of buffering the deleterious effect of stress on interaction quality. One possible mechanism between the positive associations between DC and interaction quality could be how partners verbally express their support (e.g., more we-talk) during discussions about external stress. Using real-time interaction data from 40 heterosexual couples, this project examined whether observed positive and negative DC was associated with greater (or lesser) levels of perceived interaction quality. Further, language use (i.e., pronouns, emotion words, cognition words) was assessed as mediators in the associations between DC and interaction quality. Overall, results suggested that language did not mediate the effect of DC on interaction quality; however, there were several interesting links between DC, language, and interaction quality. Implications of these findings for relationship researchers and mental health clinicians working with couples are discussed.
ContributorsLau, Kin Hang (Author) / Randall, Ashley K. (Thesis advisor) / Duran, Nicholas (Committee member) / Pereira, Jennifer (Committee member) / Arizona State University (Publisher)
Created2017
Description
Intercultural couples -partners from two different countries- may face increased levels of stress within their relationship (internal stress). Internal stress can negatively impact relationship satisfaction, whereas developing healthy ways to cope (dyadic coping; DC) can lower stress levels and improve relationship satisfaction (e.g., Bodenmann, 2005). Specifically, it may be important for partners to perceive that their partner as supporting them during times of stress through engaging in DC. This study examined whether intercultural couples experience internal stress and what effects, if any, perceived partner engagement in DC had on their reported relationship satisfaction. Cross-sectional data was gathered from 85 couples and was analyzed using Actor-Partner Interdependence Models (APIMs; Kenny & Cook, 1999). Separate APIMs were conducted to examine the association between the independent variables (perceived partner engagement in: positive DC, negative DC, delegated DC, and supportive DC) and the outcome variables of internal stress and relationship satisfaction, while controlling for years each partner lived in their country of birth, average and differences on identification with individualism-collectivism values and behaviors, and if partners did or did not identify as the same race and/or ethnicity. Additionally, APIMs of internal stress on relationship as moderated by perceived partner positive and negative DC were conducted. Results showed significant associations of all independent variables on internal stress and relationship satisfaction. There were no signification interactions between internal stress and DC on relationship satisfaction. Implications for relationship researchers and mental health professionals working with intercultural couples are discussed.
ContributorsHolzapfel, Jennifer L (Author) / Randall, Ashley K. (Thesis advisor) / Tran, Giac-Thao (Committee member) / Spanierman, Lisa (Committee member) / Arizona State University (Publisher)
Created2016