Ultra-wideband (UWB) is a revolutionary radio communication system that utilizes a large portion of the frequency spectrum while maintaining low power levels and high data rates. UWB systems can be used both indoors and outdoors within the power-level masks regulated by the Federal Communications Commission, thus making the technology very versatile. One of the main advantages of UWB is its robustness to multi-path diversity. The technology has attracted the interests of research and industry alike, owing to the possibility of implementing low-power, low-complexity, and low-cost devices. A widely recognized method of transmitting UWB signals is the use of Impulse Radio technology to transmit information. Impulse Radio Ultra-Wideband (IR-UWB) uses repetitive pulses of very short duration, low duty cycle, and low power levels within FCC regulations. One implementation of IR-UWB pulses in non-coherent transmission is the use of Differential Code-Shifted Reference (DCSR) pulses. In this technique, one of the main challenges at the receiver is pulse-level synchronization that times the received pulses at the right moments for accurate pulse detection. This thesis will introduce two design proposals in attempt to achieve the pulse synchronization. The first proposal is based on a fast-switch-controlled integrator circuit, while the second focuses on the use of an active low pass filter and phase-locked loop circuits to achieve proper clock timing. Both proposals will be presented, together with schematics, computer-aided simulations, and lab tests results.

No description available.

No description available.

This thesis presents solutions and studies related to the design of reconfigurable and wideband receiver circuits for system-on-chip (SoC) radiometer front-ends within the millimetre-wave (mm-wave) range. Whereas many of today’s mm-wave front-ends are bulky and costly due to having discrete RF components, single-chip receiver modules could potentially result in a wider use for emerging applications such as wireless communication, short range radar and passive imaging security sensors if realised with adequate performances and at a lower cost. Three main topics are considered in this thesis, monolithic integration of low-loss RF-MEMS (Dicke) switch networks and switched LNAs in MMIC/RFIC foundry processes, designs of SiGe wideband (IF) amplifier and broadband power detectors up to W-band (75-110 GHz). Low-loss and high isolation GaAs and SiGe RF-MEMS switch networks were designed and characterised for the 30-110 GHz range. A GaAs MEMS Dicke switch network has a measured minimum loss of 1 dB and maximum isolation of 19 dB at 70-96 GHz, respectively, making it a potential candidate in Dicke switched radiometer receivers. Furthermore, single-chip 30 GHz and W-band MEMS Dicke switched LNA designs have been realised for the first time in SiGe BiCMOS and GaAs mHEMT processes, respectively. For a targeted 94 GHz passive imaging application two different receiver topologies have been investigated based on direct-detection and direct-conversion (heterodyne) architectures. An optimised detector design fabricated in a 0.13 μm SiGe process achieves a more wideband input matching than earlier silicon W-band detectors and is competitive with reported III-V W-band detectors in terms of a higher responsivity and similar NEP. A SiGe 2-37 GHz high-gain differential (IF) amplifier design achieves a more wideband matching and an order of magnitude higher linearity than a recent single-ended SiGe LNA. The SiGe IF amplifier was integrated on-chip with a power detector in a 5-35 GHz IF section. Their broadband properties compared with other IF amplifier/detector RFICs, make them suitable for W-band down-conversion receivers with a larger pre-detection bandwidth and improved sensitivity. The experimental results successfully demonstrate the feasibility of the SiGe 5-35 GHz IF section for high performance SoC W-band radiometers using a more wideband heterodyne receiver architecture.

Ultra-wideband (UWB) wireless systems rely on signals spanning very wide bandwidths, typically several gigahertz, for information transmission. The distinguishing feature of UWB communications technology is the unrivalled data-rates it provides, with other benefits such as fade resistance and spectral reusability. These characteristics render UWB the technology of choice for a gamut of modern wireless communications applications, including multimedia transmission, personal- and body-area networks, imaging devices, and sensor networks. The use of wide bandwidth signals, however, leads to many complications that necessitate specialised design considerations. The propagation channel and system components acquire frequency-selective characteristics, and their nonlinear and dispersive nature, usually innocuous in a conventional setting, causes signal distortion and erroneous detection. This thesis analyses various aspects of the indoor channel and the distortion to a UWB signal propagating through it. The performance of transmitter and receiver sub-systems is evaluated, with an emphasis on the challenges posed by the large operating bandwidth. The significance of incorporating this knowledge into the system design process is demonstrated, and a novel framework for optimising the performance-complexity tradeoff is presented. • The following are the contributions of this thesis to the state of the art in UWB communications. • Experimental characterisation of the indoor UWB channel spanning the FCC band (3.1-10.6 GHz) • Demonstration of the variability of propagation characteristics in the spectral sub-bands • Assessment of frequency-dependent pathless and the consequent signal waveform distortion • Polarimetric analysis of the temporal, spectral and angular channel evolution • Evaluation of rake receiver performance and its dependence on various channel conditions • Investigation of the effect of antenna angular-spectral distortion on signal propagation • A technique for the normalisation of UWB link aberration due to antennas • Performance evaluation of diversity and spatial multiplexing with multiple-antenna systems • Design of gigabit wireless links for high data-rate applications or high user density scenarios • A novel holistic framework for the design of an optimal UWB communications system.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 215-220).

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (p. 59-63). Also available in electronic version.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 129-136). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 100-102). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xvii, 165 p.; also includes graphics (some col.). Includes bibliographical references (p. 158-165).