Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 335-340).

M.Ing. (Electrical and Electronic Engineering) / This work reports on a study in the fields of "High power pulsed power supplies and electromagnetic pulse compression". A background discussion on the application of pulsed power on lasers is given. Pulse compression and high power pulsed power supply configuration is described. The work concentrates on simultaneous energy transfer electromagnetic pulse compression which is a technique used to achieve a saving of core material in a pulse compressor. An analytical expression for the saving was derived and verified experimentally. This result is applied in different pulse compressors designed for the pulsed power supplies of copper vapour lasers. The test results are provided and discussed. A windfall from the practical work is a design solution for the voltage sharing compensation network needed when switching semiconductors in series.

D.Ing. (Electrical & Electronic Engineering) / 'Ihis thesis considers the application of non-linear, voltage dependent, saturating capacitors as turn-off snubbers for power electronic switches. The concept of using a non-linear turn-off snuJ::ber for the relieving of semiconductor switching devices is shown theoretically and experimentally. As proven by the results, the most outstanding advantage of non-linear snubbers is the much smaller quantity of energy which is being stored, during and after snubbing, in such a non-linear snubber device, compared to normal linear snubber elements. Depending on the saturation level of such a non-linear capacitor, the stored energy can (for existing ceramic capacitors) be an order of magnitude lower than the energy in a comparable linear capacitor. After the profitability of using non-linear saturating capacitors has been demonstrated, the non-linear capacitive snubber is analyzed by means of a computer simulation which uses the exact capacitancevoltage curve, as stored on data file. The circuit is, however, also analyzed analytically by approximating the non-linear capacitor characteristics in two different ways: (L) by an exponential approximation, and (ii) by a two-step piecewise linearization. Most of the results are within about 20 %of those obtained by the exact analysis, and the approximate analyses can therefore be regarded as very useful. Using the analysis of the non-linear snubber, an optimization in terms of minimum energy losses is carried out on a general turn-off snubber circuit which consists of a non-linear saturable capacitor in a regenerative snubber configuration. The equations and results are awlicable to most snubber cases. From the results it is evident that the same performance as obtained with complex linear regenerative snubber circuits can be obtained by a simple non-linear dissipative snubber...

M.Ing. / Power supplies for pulsed laser applications are required to produce high energy pulses of microsecond and sub microsecond duration. Gas phase switches have traditionally been used in these applications. The exorbitant replacement as well as running costs, coupled with the limited lifetime of these switches, has led to the investigation of the implementation of an equivalent semiconductor switch. The semiconductor switch consists of thyristors coupled in series. This switch is connected to a two stage ferrite pulse compressor in order to achieve the required output pulse shape. The use of series coupled thyristors as high voltage switches in fast switching applications has been limited to laser and radar applications. Little has been published about work in this field and it was necessary to investigate the characteristics of the switching elements, under pulsed conditions, in order to optimise the switching and conduction losses of the elements as well as the switch as a whole. This investigation led to the development of an 18 kV switch which produces 750 nanosecond pulses at a repetition rate of 10 kHz. The applicability of similar switches in the radar and laser fields is discussed.

Metal-insulator-semiconductor switches (MISS), in which the T denotes some form of thin semi-insulating layer and the semiconductor part consists of a pn junction, are part of the general class of regenerative switching devices which includes the thyristor. The switching behaviour of the MISS derives from the ability of the MIS junction to exhibit current gain and to exist in two modes, deep depletion and inversion. In this thesis, a general model for the regenerative switching is proposed after investigating the properties of the MIS junction both theoretically and experimentally. Results from MIS diodes with tunnelling-thickness oxide Mayers indicate that interface states play a dominant role in their electrical behaviour and that the uniformity of the oxide is poor, giving rise to a large spread in the current-voltage characteristics. Subsequently, the epitaxial form of the MISS device is investigated and in particular the importance of isolation of the pn junction. It is concluded that spreading effects set a practical lower limit to the device dimensions, making the epitaxial form unsuitable for microelectronic applications. An alternative semi-insulator, 'silicon-rich oxide' (SRO) is introduced as an optional I-layer with possibly greater integrity than tunnel oxide. MIS diodes formed with SRO are shown to have very similar properties to tunnelling diodes. Large area devices fabricated using this material are surprisingly discovered to exhibit stable negative differential resistance (NDR). Although this discovery at first appears to be contrary to normal circuit stability criteria and to the regenerative feedback model itself, both of these points are resolved. It is shown that the frequency of oscillation of an unstable device is controlled by the external circuit. Then it is proposed that if this frequency is greater than the maximum frequency of operation of the regenerative mechanism, stable NDR is observed. In the final chapter, alternative lateral MISS structures which should overcome the geometrical limitations of epitaxial devices are discussed.

M.Ing. / High frequency magnetic components have significant advantages related to cost and physical size compared to their low frequency counterparts. The advent of high frequency power switch technology made the transformer frequency a variable and recent advances in this field have been ever pushing the switching frequency of higher power converters. Although high frequency inductors and transformers have been used and applied extensively to an increasingly broad range of applications over recent decades, analysis and design of these devices involves certain difficulties, related to extra losses due to eddy currents as well as smaller cooling surfaces,..

by Han Dejun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [117]-[129]). / Abstract --- p.ii / Acknowledgment --- p.iv / Table of Contents --- p.v / Chapter 1. --- Introduction --- p.1-1 / Chapter 1.1 --- The Current Situation of Space-division Optical Switches --- p.1-1 / Chapter 1.1.1 --- Digital Optical switches (DOS) --- p.1-2 / Chapter 1.1.2 --- Twin-guide amplifier (TGA) --- p.1-3 / Chapter 1.1.3 --- Direction coupler with amplifiers --- p.1-4 / Chapter 1.1.4 --- Total internal reflection type switch with amplifier --- p.1-5 / Chapter 1.1.5 --- Semiconductor optical amplifier gate switches --- p.1-6 / Chapter 1.2 --- Existing Problems --- p.1-9 / Chapter 1.3 --- New Proposals --- p.1-10 / Chapter 1.3.1 --- New features --- p.1-11 / Chapter 1.3.2 --- New technology for OEIC --- p.1-13 / Chapter 1.3.3 --- Expected improvement in performance --- p.1-14 / Chapter 1.4 --- Organization of thesis --- p.1-17 / Chapter 2. --- Band Lineup And Optical Gain Calculation --- p.2-1 / Chapter 2.1 --- Introduction --- p.2-1 / Chapter 2.2 --- Band Lineup for InGaAsP MQW Structures --- p.2-3 / Chapter 2.2.1 --- Derivation According to Ishikawa et al.'s Scheme --- p.2-3 / Chapter 2.2.2 --- Derivation According to Krijn's scheme --- p.2-5 / Chapter 2.2.3 --- Improved band lineup calculation scheme --- p.2-7 / Chapter 2.3 --- Gain and Spontaneous Emission Rate Expressions --- p.2-13 / Chapter 2.3.1 --- Optical gain expressions --- p.2-13 / Chapter 2.3.2 --- Spontaneous Emission Rate Expressions --- p.2-16 / Chapter 2.3.3 --- Polarization characteristics --- p.2-17 / Chapter 2.4 --- Optical Absorption and Its Polarization Sensitivity --- p.2-18 / Chapter 2.4.1 --- Absorption in an intermixed QW Structure --- p.2-18 / Chapter 2.4.2 --- Electro-optical Absorption --- p.2-19 / Chapter 3. --- Design of the Optical Switches --- p.3-1 / Chapter 3.1 --- Design of Material Layer Structure --- p.3-2 / Chapter 3.2 --- Design of Device Geometrical Structure --- p.3-7 / Chapter 3.3 --- Optical Gain in Polarization Insensitive Gain Medium-- An Example --- p.3-8 / Chapter 3.4 --- Optical Absorption in Polarization Insensitive Gain Medium-- An Example --- p.3-15 / Chapter 4. --- Fabrication Technology --- p.4-1 / Chapter 4.1 --- Passive Waveguide Formation --- p.4-2 / Chapter 4.1.1 --- Impurity-free vacancies diffusion technology --- p.4-3 / Chapter 4.1.2 --- High energy ion implantation enhanced intermixing technology --- p.4-4 / Chapter 4.1.3 --- Elevated temperature O+ HE-IIEI of MQWs --- p.4-6 / Chapter 4.2 --- Oxygen Implant Isolation --- p.4-6 / Chapter 4.3 --- Self Aligned Ridged Waveguide Technology --- p.4-7 / Chapter 4.4 --- Reduction of Effective Facet Reflectivity --- p.4-11 / Chapter 4.5 --- Fabrication Process Flow --- p.4-12 / Chapter 4.5.1 --- Layer structure of the material --- p.4-12 / Chapter 4.5.2 --- Fabrication process flow for the Y-junction optical switches --- p.4-14 / Chapter 4.6 --- Schematic Structure of the Fabricated Switches --- p.4-19 / Chapter 5. --- Experimental Results --- p.5-1 / Chapter 5.1 --- High Energy Ion Implantation Enhanced Intermixing of Quantum Wells --- p.5-2 / Chapter 5.1.1 --- High energy ion implantation --- p.5-2 / Chapter 5.1.2 --- Rapid thermal annealing --- p.5-4 / Chapter 5.2 --- Photoluminescence --- p.5-6 / Chapter 5.3 --- Electroluminescence --- p.5-9 / Chapter 5.4 --- Current-Voltage characteristics --- p.5-12 / Chapter 5.5 --- Guided-Wave Optoelectronic Measurement --- p.5-14 / Chapter 5.5.1 --- Setup of the measurement --- p.5-14 / Chapter 5.5.2 --- Measurement of absorption loss for the blue-shifted QW structure --- p.5-16 / Chapter 5.5.3 --- Optical losses measurement by Fabry-Perot interference method --- p.5-18 / Chapter 5.5.4 --- Electroabsorption peak shift in IIEI wafer --- p.5-21 / Chapter 5.6 --- Oxygen Implant Isolation --- p.5-21 / Chapter 5.7 --- Characteristics of Optical Switches --- p.5-23 / Chapter 5.7.1 --- Current-voltage characteristics --- p.5-23 / Chapter 5.7.2 --- Optical mode and transmission characteristics --- p.5-24 / Chapter 5.7.3 --- Switch characteristics --- p.5-29 / Chapter 5.7.4 --- Discussion --- p.5-32 / Chapter 6. --- Conclusion and Future Studies --- p.6-1 / Chapter 6.1 --- Conclusion --- p.6-1 / Chapter 6.1.1 --- The major contributions to the Y-JOS --- p.6-1 / Chapter 6.1.2 --- The major contribution to the bandgap engineering for InGaAs(p)/InP heterostructure --- p.6-3 / Chapter 6.1.3 --- The major contributions to the HE-IIEI technology --- p.6-4 / Chapter 6.2 --- Topics for Future Studies --- p.6-5 / Chapter 6.2.1 --- Band lineup and optical gain calculation --- p.6-5 / Chapter 6.2.2 --- Optimization of HE-IIEI technology --- p.6-6 / Chapter 6.2.3 --- Optimization of the Fabrication of Y-JOS --- p.6-7 / Reference --- p.R1 / Appendix A Characteristics Of Strained Quantum Wells --- p.A1 / Appendix B Effective Index Change Induced by Quantum Well Intermixing --- p.A3 / Appendix C Abbreviation --- p.A13 / Appendix D List of Publications --- p.A14

prepared by Ling Hok Sun, Lawrence. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Abstract also in Chinese. / Chapter 1. --- Abstract --- p.2 / Chapter 2. --- Introduction --- p.3 / Chapter 3. --- Circuit Description --- p.8 / Chapter 4. --- Technology' --- p.10 / Chapter 5. --- Design --- p.13 / Chapter 5.1 --- TOP LEVEL --- p.13 / Chapter 5.2 --- Logic --- p.14 / Chapter 5.3 --- Tuner --- p.19 / Chapter 5.4 --- Gate Drive and Power Switch --- p.26 / Chapter 5.5 --- Full-Circuit Simulation --- p.43 / Chapter 6. --- Layout --- p.53 / Chapter 7. --- Characterization --- p.55 / Chapter 8. --- Conclusion --- p.65 / Chapter 9. --- Reference --- p.66 / Chapter 10. --- Appendix --- p.67

In this paper, an analysis of the clock-feedthrough effects in switched-current (SI)' circuits will be presented. The clock-feedthrough effects caused by the non-ideal characteristic of MOS switches when they are turned off limit the accuracy of the analog track-and-hold (T/H) circuits. A model to analyze and characterize this effect is established. A current-feedthrough cancellation technique is developed for analog/digital applications. This circuit allows SI filters to be implemented with small transistor sizes and still performs relatively well compared with the existing techniques. A SI lowpass biquadratic filter with a cutoff frequency of 5 KHz and a SI T/H circuit were implemented and fabricated using a two micron P-well CMOS process technology from MOSIS (MOS Integration Service). / Graduation date: 1992

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