Thesis (Ph.D.) - Carleton University, 2005. / Includes bibliographical references (p. 170-180). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 75-77). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 130-135). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 106-108). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 150-155).

Thesis (M.S.E.C.E. )--University of Massachusetts Amherst, 2008. / Includes bibliographical references (p. 84-88).

Thesis (MTech (Electrical Engineering)--Cape Peninsula University of Technology, 2011 / Modern technologies have led to extensive digital music reproduction and distribution. It is fitting then that digital audio be amplified directly from its source rather than being converted to an analogue waveform before amplification. The benefits of using a digital controller for audio processing include being able to easily reconfigure the system and to add additional functions at a later stage. Digital audio is primarily stored as Pulse Code Modulation (PCM) while Pulse Width Modulation (PWM) is the most popular scheme used to drive a class-D amplifier. The class-D amplifier is selected in many applications due to its very high energy efficiency. Conventional PCM to PWM conversion is inherently nonlinear. Various interpolation schemes are presented in this research project which help to address the nonlinearity. Digitally generated PWM has a limited resolution which is constrained by the system clock. This thesis presents noise shaping techniques which increase the effective resolution of the PWM process without having to use an excessively high system clock. Noise shaping allows a low resolution modulator to be used to reproduce high resolution audio.

Receiver sensitivity is an important parameter in the design of optical communication systems. Prior results on receiver sensitivity for on-off keying modulated direct detection systems with an optical preamplifier are generalized for the cases of frequency-shift keying and subcarrier modulation. Our results, obtained by using the Gaussian approximation, are compared to those obtained by an 'exact' analysis. The results are also generalized for N-ary modulation schemes and systems having optical amplifiers as linear repeaters. Simple analytic formulae are derived for the maximum system gain of optical amplifiers systems for the following two cases: 1) Constant signal power at each amplifier. 2) Equal amplifier spacing, which ensures constant total power at each amplifier. The functional dependence of system gain on various system parameters, and the effects of optical filtering at the receiver as well as at the intermediate amplifiers, is studied. The analysis is extended to include the effects of random power variations at the output of each amplifier. / Master of Science

The objective of this research is to develop, characterize, and demonstrate novel parametric architectures capable of wideband operation while maintaining high gain and stability. To begin the study, phase-incoherent upconverting parametric amplifiers will be explored by first developing a set of analytical models describing their achievable gain and efficiency. These models will provide a set of design tools to optimize and evaluate prototype circuit boards. The prototype boards will then be used to demonstrate their achievable gain, bandwidth, efficiency, and stability. Further investigation of the analytical models and data collected from the prototype boards will conclude bandwidth and gain limitations and end the investigation into phase-incoherent upconverting parametric amplifiers in lieu of negative-resistance parametric amplifiers. Traditionally, there were two versions of negative-resistance parametric amplifiers available: degenerate and non-degenerate. Both modes of operation are considered single-frequency amplifiers because both the input and output frequencies occur at the source frequency. Degenerate parametric amplifiers offer more power gain than their non-degenerate counterpart and do not require additional circuitry for idler currents. As a result, a phase-coherent degenerate parametric amplifier printed circuit board prototype will be built to investigate achievable gain, bandwidth, and stability. Analytical models will be developed to describe the gain and efficiency of phase-coherent degenerate parametric amplifiers. The presence of a negative resistance suggests the possibility of instability under certain operating conditions, therefore, an in-depth stability study of phase-coherent degenerate parametric amplifiers will be performed. The observation of upconversion gain in phase-coherent degenerate parametric amplifiers will spark investigation into a previously unknown parametric architecture: phase-coherent upconverting parametric amplifiers. Using the phase-coherent degenerate parametric amplifier prototype board, stable phase-coherent upconversion with gain will be demonstrated from the source input frequency to its third harmonic. An analytical model describing the large-signal transducer gain of phase-coherent upconverting parametric amplifiers from the first to the third harmonic of the source input will be derived and validated using the prototype board and simulations.

Thesis (M.Eng.(Electronic Engineering))--University of Pretoria, 2008. / Summaries in Afrikaans and English. Includes bibliographical references (leaves [92]-99).