Design of low power Turbo decoder is one of the key issues in many modern communication systems such as 3 GPP. For the Turbo decoder architecture, the memory for the storage of the branch metric and state metric represents a major part of the entire decoder no matter in silicon area or power dissipation. Therefore, instead of saving the computed branch memory, this thesis adopts an alternative approach by saving the input in order to generate the branch memory on line. Furthermore, a novel design of state metric unit is proposed such that the size of the total state metric can be effectively reduced by a half with slightly overhead of adders/subtractors. For non-recursive systematic encoding applications, the same design methodology can further reduce the number of arithmetic units required in the soft-output calculating module. Our preliminary experimental result shows that the proposed design methodology can achieve 40% and 13% reduction on the gate count and power dissipation respectively.

Two kinds of low distortion switching power amplifiers are presented in this thesis. In the first power amplifier, we use feedback and low voltage low power circuits to improve the distortion and power efficiency. In the second power amplifier, we use ring oscillator and Noise shaping to construct the circuit and filters are added in the feedback loop to reduce the quantization noise. HSPICE simulations and experimental results verify the proposed circuits. Experimental results show that the THDs of both circuits are all lower than 0.27% at 1.5V supply voltage. This result shows that the proposed power amplifiers have superior performance in THD, and these circuits are applicable to low-distortion, high-efficiency, and low-voltage applications, such as the hearing instruments.

Abstract As integrated circuit dimensions continue to shrink, interconnect RC delay becomes an increasingly serious problem. Fabrication of interconnect structures using new materials of low resistivity and low permittivity to replace the traditional Al and SiO2 interconnect technology is in high demand. Specially, copper and low dielectric constant (low-k) polymers show great promise. Among various low-k materials, spin-on glass (SOG) materials have been widely used as an interlayer dielectric in multilevel interconnections because they are applied easily and have relatively low process costs. One class of materials, which offers many of properties of silica (SiO2) hardness, thermal and dimensional stability etc.) are the HOSP (Hybrid Organic-Siloxane-Polymer)and HSQ (Hydrogen Silsesquioxane) represent an important member of this family. HOSP and HSQ exhibits a relatively low dielectric constant (k=2.6-2.8) as compared to SiO2 (k=4.0).It is intrinsically hydrophobic, has reasonable mechanical hardness, and possesses exceptional thermal and dimensional stability (in excess of 400¢J). For these reasons, HOSP and HSQ represent an excellent candidate for applications on the multilevel interconnect architecture. On the other hand, etching and PR removal are key technology during the manufactures of multilevel interconnects. X-ray lithography process is adopted to avoid these issues. As a result, a novel X-ray lithography technology for the low-k interlayer has been proposed for fabrication of IC. And it is a low cost process. In this work, the characteristics of PR removal have been investigated. Experimental results have shown that the dielectric properties of HOSP and HSQ are degraded by PR removal process. The X-ray exposure will solve these problems and it will be a useful tool in advance ICs fabrication. The advantage of the X-ray exposure is the direct patterning, avoids the issues during the etching and photoresist striping processes. The part of film exposed by X-ray will be cured and the other part could be dissolved with the solvent. Strictly speaking, these two issues will be overcome by the X-ray curing.

In this thesis we synthesize Pr1.85Ce0.15CuO4 system by mean of X-ray diffraction, electrical resistivity, magnetic susceptibility and low-temperature specific heat. From these data analysis, we hope to more clearly understand the transition of electron-doped superconductor Pr2-xCexCuO4 (0.14<x<0.7) system. The main results show that the system is d-wave pairing symmetry. This conclusion is consisted with C. C. Tsuei¡¦s result. They present phase-sensitive evidence that the electron-doped cuprates Pr1.85Ce0.15CuO4 have d-wave pairing symmetry.

In this thesis, we present an implementation of a low-power digital signal processor. We design the hardware units and analyze the instruction set for digital signal process applications. Besides, the power consumption issue is considered. We present two solutions to reduce the power consumption. We also discuss the test pattern generations to verify this DSP processor. Finally, the concept of IP design is considered in this design.

Two novel ultra-low-voltage (ULV) low-power (LP) variable gain amplifiers (VGA) are presented in this paper. These amplifiers based on complementary MOS transistors operating in weak inversion region are composed of pseudo-exponential current-to-current converters and analog multipliers. The gain of the amplifiers can be controlled by an exponential function circuit. The proposed circuits have been verified with the 0.25£gm CMOS technology by HSPICE simulations. The simulation results confirm the feasibility of the proposed VGAs.

The Energy Policy Act of 1992 mandated that bathroom plumbing fixtures manufactured in the United States after January 1, 1994 meet standards for maximum water consumption. Manufacturers have developed low-consumption valves to meet these standards. The performance of low-consumption fixtures has become an important issue for facilities managers because the water saving by retrofitting low-consumption fixtures is significant. The fixtures in the Langford Architecture Building A, Texas A&M University were used to conduct this study. An acoustic information retrieval system was utilized to collect the sound signals of each fixture and a speech recognition system was utilized to identify which fixture was in use. The data from this study were analyzed to determine whether location of fixture and type of fixture—manual or automatic—caused a significant difference in frequency of use.

This work presents the validation and enhancement of existing correlations for estimating and predicting the permeability in low permeability gas sands. The "original" problem of predicting the corrected or "liquid equivalent" permeability has been under investigation since the early 1940s — in particular, using the application of "gas slippage" theory to petrophysics by Klinkenberg. In the first part of this work, the viability of the Jones-Owens and Sampath-Keighin correlations for estimating the Klinkenberg-corrected (absolute) permeability from single-point, steady-state measurements were investigated. We also provide an update to these correlations using modern petrophysical data. In the second part of this work we proposed and validated a new "microflow" model for the evaluation of an equivalent liquid permeability from gas flow measurements. This work was based on a more detailed application of similar concepts employed by Klinkenberg. In fact, we obtained the Klinkenberg result as an approximate form of this result. A theoretical "microflow" result was given as a rational polynomial (i.e., a polynomial divided by a polynomial) in terms of the Knudsen number (ratio of the mean free path of the gas molecules to the characteristic flow length (typically the radius of the capillary)), and this result can be applied as an explicit correlation device, or as an implicit prediction model (presuming the model is tuned to a particular data set). The following contributions are derived from this work: ● Validation and extension of the correlations proposed by Jones-Owens and Sampath-Keighin for low permeability samples. ● Development and validation of a new "microflow" model which correctly represents the flow of gases in low permeability core samples. This model is also applied as a correlation for prediction of the equivalent liquid permeability in much the same fashion as the Klinkenberg model, although the new model is substantially more theoretical (and robust) as compared to the Klinkenberg correction model.

With the current trend towards integration and higher data rates, read channel design needs to incorporate significant boost for a wider signal bandwidth. This dissertation explores the analog design problems associated with design of such 'Equalizing Filter' (boost filter) for read channel applications. Specifically, a 330MHz, 5th order Gm-C continuous time lowpass filter with 24dB boost is designed. Existing architectures are found to be unsuitable for low power, wideband and high boost operation. The proposed solution realizes boosting zeros by efficiently combining available transfer functions associated with all nodes of cascaded biquad cells. Further, circuit techniques suitable for high frequency filter design are elaborated such as: application of the Gilbert cell as a variable transconductor and a new Common-Mode-Feedback (CMFB) error amplifier that improves common mode accuracy without compromising on bandwidth or circuit complexity. A prototype is fabricated in a standard 0.35mm CMOS process. Experimental results show -41dB of IM3 for 250mV peak to peak swing with 8.6mW/pole of power dissipation.

Characteristics of emitters under low pressure are essential for designing drip irrigation systems. Low pressure data for drip emitters are not available from manufacturers. A laboratory test was conducted to evaluate the performance of five types of newly manufactured drip tapes, especially under a low pressure distribution system. The five drip products that were tested were (i) Toro Drip in PC (PCS 1810-18- 100), (ii) T-Tape (TT15-1245-0100), (iii) Mister_LS (MLD-HDT100), (iv) Mister_PS (MLD-1PC 25), and (v) Netafim (Techline CV 560 050). Drip tapes tested in this study have design discharge rates of 4.00 L/hr @ 206.84 Kpa (1.06 gph @ 30 psi), 1.02 L/hr @ 55.16 Kpa (0.27 gph @ 8 psi), 3.785 L/hr @ 172.37 Kpa (1.00 gph @ 25 psi), 3.785 L/hr @172.37 Kpa (1.00 gph @ 25 psi), and 0.984 L/hr @ 206.84 Kpa (0.26 gph @ 20psi), respectively. All of them, except T-Tape, were pressure compensating (PC) emitters; the T-Tape was non-pressure compensating (NPC). For all products, except Toro, the emitter spacing was 0.305 m (12 inches) and for Toro, it was 0.46 m (18 inches). Mister_PS (MLD-1PC 25) was the point source (PS) emitter and all others were line source emitters. Drip products were tested with 15 different operating pressures ranging from 5.97 KPa (0.87 psi) to 344.74 KPa (50.00 psi). From an evaluation of 60 emitters from each product, the Toro brand showed an average uniformity coefficient (UC) of 91.24 %, with a coefficient of variation (Cv) of 0.06, T-Tape drip products showed an average UC of 96.63 % with a Cv of 0.04, Mister_ LS showed an average UC of 93.12 % with a Cv of 0.08, Mister_PS showed an average UC of 96.33 % with a Cv of 0.04, and Netafim showed an average UC of 97.92 % with a Cv of 0.02. Flow rate vs. pressure head (Q-H) curves were also developed for each drip emitter tested. From emitter exponent values it was observed that all of the pressure compensating (PC) products behaved like NPC emitters at low pressures, although they behaved like PC emitters under normal operating pressures. From statistical analysis, it was determined that except for Netafim product, all other tested products were effective under low operating pressures as were under high operating or recommended pressures. Netafim product had no emission under low pressures. Using the measured average emission rate and developed Q-H curves, the distribution uniformities of all products except Netafim were calculated under low pressure ranges of 5.97 KPa (0.87 psi) to 23.88 KPa (3.50 psi ) for different lengths of laterals and under 0%, 1%, 2%