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A system-on-chip (SoC) with near-threshold supply voltage (NTV) operation has received a significant amount of attention. Its high energy-efficiency supports a number of low-power emerging applications such as wireless sensor networks and Internet-of-Thing edge devices. Integrating various digital, analog, mixed-signal, and power sub-systems, such SoC designs need to employ tens of voltage domains to push the envelope of energy-efficiency, performance, and robustness. A low-drop-out (LDO) regulator is a key building block for creating voltage domains on a chip thanks to its high power density. In particular, its digital implementation, i.e., digital LDO, recently has emerged as a popular topology since it can support a wide range of input voltage from super-threshold to near-threshold voltage regimes, while conventional analog LDOs become less effective. One of the critical overheads in existing digital LDO designs is a requirement of off-chip output capacitor for stabilizing the output voltage, due to inadequate latency in active control paths. It is possible to employ higher clock frequency in a digital LDO; however such solutions inevitably increase power dissipation. This off-chip capacitor overhead can significantly increase chip pin count and printed circuit board (PCB) space, thus limiting the number of power domains that an SoC can have. This thesis presents my research on fully-integrated digital LDO designs based on event-driven control architecture. My research focuses on scaling down the output capacitor size to the integrable level and improving transient performance such as maximum voltage change and settling time. To shrink the output capacitor size, we introduced the event-driven control and the binary digital PI controller in our first event-driven LDO design. Thanks to the event-driven control, we achieved control loop latency reduction without compromising power consumption, leading to output capacitor size reduction. The first design shows 2.7x improvement over the previous digital LDO designs in Figure-of-Merit with a 400pF of output capacitor. To further reduce output capacitor size and support larger load current, we implemented the second event-driven digital LDO designs with fine-grained parallelism. The parallel structure of its PI controller reduces the latency of the proportional part, which mainly regulates output voltage, so it achieves better transient performance with reduced size of capacitor. Also, the parallel-shift-register-based integration part lowers computation and area overheads. The second design outperforms the state of the arts by over 17x in Figure-of-Merits with only a 100pF of output capacitor. In the last design, we introduced initialization and self-triggering control. The initialization estimates load current change in the beginning of regulation process and sets the controller output close to the desired value. This leads to substantial reduction of settling time. Also, thanks to self-triggering control, the hardware overhead from counting the event interval is removed without the first response time degradation, achieving high current density. The last design with a 100pF of output capacitor improves settling time and current density by 3.8x and 6.7x, respectively, while achieving comparable transient performance in terms of Figure-of-Merit.

Thesis (M.Eng.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 115-120.

Call number: LD2668 .T4 1957 A88 / Master of Science

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A new approach has been introduced to characterize the epidermal growth factor receptors and their relation to the mechanism of cell growth control using hybrid cells made between human EGF responsive cells and mouse A9 cells incapable of EGF binding. BALBc mice were immunized with human carcinoma A431 cells carrying an extraordinary high number of EGF receptors; antisera were used to identify the human nature of EGF receptors in these hybrid cells. One of the hybrid lines, C2B5, that retains only one human chromosome, an X/7 translocation, and a nearly complete mouse parental genome was used to analyze the relationship of the binding ability and certain post-receptor functions to the cellular mitogenic response. It was shown that the ability to bind, internalize and degrade the ligand and/or its receptor is not sufficient for cells to respond to the mitogen. Spleen cells from mice immunized with A431 cells were fused with mouse myeloma P3NP cells. One of the isolated hybridoma lines, B4G7, secreted a monoclonal antibody of the IgG class which inhibits the binding of ¹²⁵I-EGF to A431 and human fibroblasts, but not of mouse 3T3 cells. This inhibition was partial (65-70%) and Scatchard analysis of the binding data suggested that antibody preferentially interacts with a low affinity class of EGf receptors. The antibody specifically precipitated EGF receptor from radiolabeled cells. This monoclonal antibody was crosslinked to subunit A of toxic ricin through a disulfide bond. The resulting conjugate inhibited protein synthesis of A431 cells at 4 x 10⁻¹¹M and exhibited substantial cell killing. Using this conjugate we isolated a variant of A431 cells, designated C1-B7, with approximately 30 times less EGF binding capacity. Contrary to the parental A431, this variant is resistant to EGF-induced suppression of cell growth and appears to have lost most of the low affinity receptors. The high affinity type EGF receptors retained by the variant are 170,000 Mr and susceptible to EGF-induced phosphorylation, presumably on tyrosine residues. In membrane prepared from this variant, besides the EGF receptor, a low molecular weight component of as yet unknown nature is highly phosphorylated in an EGF-independent manner.

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A Dissertation Submitted to the Faculty of SCience University of the Witwatersrand, Johannesburg In fulfilment of the requirements for the Degree of Doctor of Philosophy / Living cells are highly auto-dynamic entities which means that the underlying biochemistry is equally dynamic, a reality which is ignored by most researchers. Theoretical studies indicate that such a state must be due to the existence of oscillatory variations in the levels and activities of key components in the cell. In this study, the dynamic behaviour of four major, interrelated areas of cell biochemistry (phosphorylation, dephosphorylation, the terminal reaction of glycolysis and the amount of soluble protein) were examined and all systems found to oscillate in murine erythroleukaemic cells (MEL) and, where examined, also in the human HL-60 leukaemic cell line. (Abbreviation abstract) / AC 2018