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Development of Indium Arsenide Quantum Well Electronic CircuitsBergman, Joshua 09 July 2004 (has links)
This dissertation focuses on the development of integrated circuits that employ InAs quantum well electronic devices. There are two InAs quantum well electronic devices studied in this work, the first being the pseudomorphic InAs/In₀.₅₃Ga₀.₄₇As/AlAs resonant tunneling diode (RTD) grown on an InP substrate, and the second being the InAs/AlSb HEMT. Because of there is no semi-insulating substrate near the InAs lattice constant of 6.06 Å this work develops monolithic and hybrid integration methods to realize integrated circuits. For the case of hybrid RTD circuits, a thin-film integration method was developed to integrate InAs/In₀.₅₃Ga₀.₄₇As/AlAs RTDs to prefabricated CMOS circuits, and this technique was employed to demonstrate a novel RTD-CMOS comparator. To achieve higher speed circuit operation, a next-generation RTD fabrication process was developed to minimize the parasitic capacitance associated with the thin-film hybridization process. This improved fabrication process is detailed and yield and uniformity analysis is included. Similar InP-based tunnel diodes can be integrated with InP-based HEMTs in monolithic RTD-HEMT integrated circuits, and in this work elementary microwave circuit components were characterized that co-integrate InP-based tunnel diodes with HEMTs. In the case of the InAs/AlSb HEMT, the monolithic approach grows the HEMT on a metamorphic buffer on a GaAs substrate. The semiconductor material and process development of the InAs/AlSb HEMT MMIC technology is described. The remarkable microwave and RF noise properties of the InAs/AlSb HEMT were characterized and analyzed, with special attention given to the strong effects of impact ionization in the narrow bandgap InAs channel. Results showed the extent to which impact ionization affects the small-signal gain and noise figure of the HEMT, and that these effects become less prevalent as the frequency of operation increases.
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Front-end considerations for next generation communication receiversRoy, Mousumi January 2011 (has links)
The ever increasing diversity in communication systems has created a demand for constant improvements in receiver components. This thesis describes the design and characterisation of front-end receiver components for various challenging applications, including characterisation of low noise foundry processes, LNA design and multi-band antenna design. It also includes a new theoretical analysis of noise coupling in low noise phased array receivers.In LNA design much depends on the choice of the optimum active devices. A comprehensive survey of the performance of low noise transistors is therefore extremely beneficial. To this end a comparison of the DC, small-signal and noise behaviours of 10 state-of-the-art GaAs and InP based pHEMT and mHEMT low noise processes has been carried out. Their suitability in LNA designs has been determined, with emphasis on the SKA project. This work is part of the first known detailed investigation of this kind. Results indicate the superiority of mature GaAs-based pHEMT processes, and highlight problems associated with the studied mHEMT processes. Two of the more promising processes have then been used to design C-band and UHF-band MMIC LNAs. A new theoretical analysis of coupled noise between antenna elements of a low noise phased array receiver has been carried out. Results of the noise wave analysis, based on fundamental principles of noisy networks, suggest that the coupled noise contribution to system noise temperatures should be smaller than had previously been suggested for systems like the SKA. The principles are applicable to any phased array receiver. Finally, a multi-band antenna has been designed and fabricated for a severe operating environment, covering the three extremely crowded frequency bands, the 2.1 GHz UMTS, the 2.4 GHz ISM and the 5.8 GHz ISM bands. Measurements have demonstrated excellent performance, exceeding that of equivalent commercial antennas aimed at similar applications.
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