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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A 1.25GS/s 8-bit Time-interleaved C-2C SAR ADC for Wireline Receiver Applications

Wang, Qiwei 11 December 2013 (has links)
Many wireline communication systems are moving toward a digital based architecture for the receiver that requires a front-end high-speed ADC. This thesis proposes a two-level time-interleaving topology for realizing such an ADC, comprising front-end time-interleaved sub-rate track-and-holds each followed by a sub-ADC which is further time-interleaved to a slower clock frequency. The design, implementation and measurement of the 1.25GS/s sub-ADC fabricated in 65nm CMOS technology is presented. The SAR architecture is chosen for its low power and digital friendly nature along with an unconventional C-2C capacitive DAC implementation for higher bandwidth. The time-interleaved C-2C SAR ADC runs with a 1.0V supply, and it has a full input range of 1.0V\subscript{pp} differential, while consuming 34mW. The SNDR is 39.4dB at low frequency and the FOM is 360fJ/conv-step and 428fJ/conv-step at low and Nyquist input frequencies respectively. The SNDR is 34dB at 4GHz input frequency, which is more than 6 times the Nyquist frequency.
2

Combinational Multiphoton Scanning Microscopy and Multiphoton Surgery of Mouse Arteries

Karimelahi, Samira 30 May 2011 (has links)
Preliminary investigations were carried out in order to explore the potential of laser-stimulated capillary growth in a blood vessel-on-a-chip. To fulfill the project objective, a series of experiments in both directions of two photon fluorescence imaging and laser-semitransparent materials interaction were performed. A purpose-built two-photon fluorescence imaging resolution was tested by imaging 1 micron diameter fluorescent beads. Also, the potential of fluorescence imaging in the waveguide writing eld as well as the biological eld was studied. Further, for laser ablation on the mouse artery loaded in the microfluidic channel, the processing window was found such that the damage induced by femtosecond laser just a effects the artery, not the other interfaces of the microfluidic chip. At the end, the result of laser trepanning on the mouse artery wall combined with two photon fluorescence imaging was shown. These results will be useful for more advanced biological study such as angiogenesis.
3

Combinational Multiphoton Scanning Microscopy and Multiphoton Surgery of Mouse Arteries

Karimelahi, Samira 30 May 2011 (has links)
Preliminary investigations were carried out in order to explore the potential of laser-stimulated capillary growth in a blood vessel-on-a-chip. To fulfill the project objective, a series of experiments in both directions of two photon fluorescence imaging and laser-semitransparent materials interaction were performed. A purpose-built two-photon fluorescence imaging resolution was tested by imaging 1 micron diameter fluorescent beads. Also, the potential of fluorescence imaging in the waveguide writing eld as well as the biological eld was studied. Further, for laser ablation on the mouse artery loaded in the microfluidic channel, the processing window was found such that the damage induced by femtosecond laser just a effects the artery, not the other interfaces of the microfluidic chip. At the end, the result of laser trepanning on the mouse artery wall combined with two photon fluorescence imaging was shown. These results will be useful for more advanced biological study such as angiogenesis.
4

Conducting Nanocrystal Solids for Optoelectronic Devices

Shukla, Harnik 30 July 2008 (has links)
Nanocrystal solids represent an exciting new class of materials. These are often referred to as artificial solids, in which the nanocrystals take the place of atoms in traditional solids. This thesis reports the utility of field-effect transistor measurements to elucidate charge transport parameters, such as charge carrier density and charge carrier mobility in a nanocrystal solid. The evolution of these parameters with chemical treatments is followed and correlated to improved performance in photovoltaic devices. Chemical treatments are demonstrated to simultaneously engineer interparticle spacing, doping and electronic coupling in nanocrystal solids. The nanocrystal solids are then utilized as building blocks for fabricating all nanocrystal heterostructure. A type-I nanocrystal heterostructure is fabricated to demonstrate efficient electroluminescent device in the infrared communications wavelength. The device emits at peak wavelength of 1.58 um with an effciency of 0.5%.
5

Gain-reconfigurable Current-sensing Circuit for High-frequencey Low-power DC-DC Converters

Yiu, Chun-Chee Francis 07 April 2010 (has links)
A novel current-sensing circuit that can operate from 1MHz to 4MHz has been designed and implemented for high-frequency low-power dc-dc power converter applications. The design is based on SenseFET concept with embedded SenseFETs in the main switch (MS) and synchronous rectifier (SR). An intermediate RC filter merges outputs from the MS and SR SenseFETs and supplies a smooth voltage signal to an op-amp. This reduces the need for a very high gain-bandwidth op-amp circuit and improves the efficiency of the power converter. The circuit has configurable feedback gain in order to increase current sensing accuracy when the average inductor current is small.
6

Conducting Nanocrystal Solids for Optoelectronic Devices

Shukla, Harnik 30 July 2008 (has links)
Nanocrystal solids represent an exciting new class of materials. These are often referred to as artificial solids, in which the nanocrystals take the place of atoms in traditional solids. This thesis reports the utility of field-effect transistor measurements to elucidate charge transport parameters, such as charge carrier density and charge carrier mobility in a nanocrystal solid. The evolution of these parameters with chemical treatments is followed and correlated to improved performance in photovoltaic devices. Chemical treatments are demonstrated to simultaneously engineer interparticle spacing, doping and electronic coupling in nanocrystal solids. The nanocrystal solids are then utilized as building blocks for fabricating all nanocrystal heterostructure. A type-I nanocrystal heterostructure is fabricated to demonstrate efficient electroluminescent device in the infrared communications wavelength. The device emits at peak wavelength of 1.58 um with an effciency of 0.5%.
7

Gain-reconfigurable Current-sensing Circuit for High-frequencey Low-power DC-DC Converters

Yiu, Chun-Chee Francis 07 April 2010 (has links)
A novel current-sensing circuit that can operate from 1MHz to 4MHz has been designed and implemented for high-frequency low-power dc-dc power converter applications. The design is based on SenseFET concept with embedded SenseFETs in the main switch (MS) and synchronous rectifier (SR). An intermediate RC filter merges outputs from the MS and SR SenseFETs and supplies a smooth voltage signal to an op-amp. This reduces the need for a very high gain-bandwidth op-amp circuit and improves the efficiency of the power converter. The circuit has configurable feedback gain in order to increase current sensing accuracy when the average inductor current is small.
8

A 1.25GS/s 8-bit Time-interleaved C-2C SAR ADC for Wireline Receiver Applications

Wang, Qiwei 11 December 2013 (has links)
Many wireline communication systems are moving toward a digital based architecture for the receiver that requires a front-end high-speed ADC. This thesis proposes a two-level time-interleaving topology for realizing such an ADC, comprising front-end time-interleaved sub-rate track-and-holds each followed by a sub-ADC which is further time-interleaved to a slower clock frequency. The design, implementation and measurement of the 1.25GS/s sub-ADC fabricated in 65nm CMOS technology is presented. The SAR architecture is chosen for its low power and digital friendly nature along with an unconventional C-2C capacitive DAC implementation for higher bandwidth. The time-interleaved C-2C SAR ADC runs with a 1.0V supply, and it has a full input range of 1.0V\subscript{pp} differential, while consuming 34mW. The SNDR is 39.4dB at low frequency and the FOM is 360fJ/conv-step and 428fJ/conv-step at low and Nyquist input frequencies respectively. The SNDR is 34dB at 4GHz input frequency, which is more than 6 times the Nyquist frequency.
9

Plug-and-play Digital Controllers for Scalable Low-power Switch-mode Power Supplies

Weinstein, Jason 17 February 2010 (has links)
The purpose of this thesis is to present a novel controller structure for scalable switch-mode power supplies targeting low power applications. The design employs masterless control, where each phase is responsible for its own control in a multiphase system. The controller is capable of automatically configuring itself to work with a single phase system or a multiphase system. The configuration process allows each controller to determine the number of phases in the system, as well as to synchronize and sequence the phases. With this architecture, the same controller design can be used in many types of applications requiring different numbers of phases, resulting in a decrease in cost and design effort. The proposed design has been verified experimentally on FPGA and IC implementations.
10

Completion Delay Minimization for Instantly Decodable Network Coding

Sorour, Sameh 31 August 2011 (has links)
Instantly Decodable Network Coding (IDNC) is a subclass of opportunistic network coding that has numerous desirable properties for a wide spectrum of applications, namely its faster decoding delay, simpler coding and decoding processes, and no decoding buffer requirements. Nonetheless, IDNC suffers from two main problems that may limit its attractiveness, as an implementable solution in future wireless networks, against full network coding (FNC), widely studied in the literature. First, it cannot guarantee the decoding of a new packet at each receiver in each transmission, which may severely affect its completion delay. Second, it requires full feedback in order to operate properly, which may be prohibitive for several practical network settings. In this thesis, we aim to reduce the effect of these drawbacks by studying the problems of minimizing the IDNC completion delay in full and limited feedback scenarios. Since completion delay cannot be optimized only through local decisions in each of the transmissions, we first study the evolution of the IDNC coding opportunities and determine the strategies maximizing them, not only for one transmission, but for all future transmissions. We then formulate the completion delay problem as a stochastic shortest path (SSP) problem, which turns out to be of extremely large dimensions that makes its optimal solution intractable. Nonetheless, we exploit the structure of this SSP and the evolution of the coding opportunities to design efficient algorithms, which outperform FNC in most multicast scenarios and achieve a near-optimal performance in broadcast scenarios. However, since FNC still outperforms IDNC in some network scenarios, we design an adaptive selection algorithm that efficiently selects, between these two schemes, the one that achieves the smaller completion delay. To study the effect of feedback reduction, we formulate the completion delay minimization problem, for the cases of intermittent and lossy feedback, as extended SSP and partially observable SSP problems, respectively. We show that these new formulations have the same structure of the original SSP. We thus extend the designed algorithms to operate in intermittent and lossy feedback scenarios, after taking update decisions on the attempted and un-acknowledged packets. These redesigned algorithms are shown to achieve tolerable degradation for relatively low feedback frequencies and high feedback loss rates.

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