Low-power and small size analog to digital converters (ADCs) are the strategic building blocks in state of the art mobile wireless communication systems. Various techniques have been developed to reduce both power consumption and die area of the ADC. Among these, the opamp-sharing technique shows the most promise. In opamp-sharing, power and die area are saved by sharing one opamp between two successive pipeline stages. However, this technique suffers from the well-known memory effect drawback due to the absence of the reset phase that discharges the opamp's input parasitics. In this dissertation, this drawback is solved by introducing a discharge phase before the opamp is used for the pipeline stages without compromising speed and resolution of the ADC. Further power and area reduction is achieved by using a capacitor-sharing technique. This technique reduces the effective load capacitance of the opamp by reusing the charge on the feedback capacitor for the MDAC operation of the following stage, resulting in faster settling without increasing opamp power. The proposed low input-capacitance variable-gm opamp also helps to reduce the memory effect and improves the settling behavior of the stage output by increasing the bandwidth of the opamp while input parasitics of the opamp are kept small. The prototype designs of a 10-bit 50MSample/s pipelined ADC and a 14-bit 100MSample/s pipelined ADC implemented in 0.18¹m CMOS technology demonstrate the effectiveness of the proposed techniques. The first ADC achieves 56.2dB SNDR and 72.7dB SFDR for a Nyquist input at full sampling rate while consuming 12 mW from a 1.8-V supply. The FOM, defined as, [power/2[superscript ENOB].Fs], is 0.46 pJ/step with Fin = 24.5MHz at 50MS/s. The second ADC achieves 72.4dB SNR and 88.5dB SFDR at 100MS/s with a 46MHz input and consumes 230mW from a 3V supply. The FOM of the second ADC is 0.69 pJ/step with Fin = 46MHz at 100MS/s.

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In the present work, investigations are carried out for the ultimate use of the "Bis table Fluid Amplifier" as an alternator to produce intermittent vertical water slugs. The effect of some geometrical and flow variables on the amplifier characteristics used in a vertical position, is studied experimentally. The minimum control flow required to switch the main power jet from one wall to the other is obtained as a function of the main jet flow rate, the splitter angle and its distance from the main nozzle. The efficiency of the amplifier functioning as a pressure recovery device is determined in relation to the output load. Theoretical and experimental results are compared. Some aspects of downwards air water flow in long vertical tubes are investigated. The formation of a spherical-cap air slug in an overflow pipe, and the behaviour and stability of the air-water interface in the tube are studied with the aid of motion picture films. Finally, a theory is appended concerning the transient polytropic compression of a gas in a vertical tube by a high velocity falling liquid slug from a constant flow supply.

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The combination of the arsenic trisulfide (As2S3) waveguide and titanium diffused lithium niobate (Ti:LiNbO3) waveguide provide us compact and versatile means for transmitting and processing optical signals, which benefits from the high index contrast between these two materials and the electro-optical properties of Ti: LiNbO3. Furthermore, waveguide gain is introduced through selective surface erbium (Er) doping which yields high quality loss-compensated or even amplifying waveguides without disturbing the excellent electrooptical, acoustooptical and nonlinear properties of the waveguide substrate LiNbO3. The integration of these waveguides allows the development of a whole class of new waveguide devices of higher functionality and complexity. As one kind of the hybrid waveguide devices, a new configuration consisting of an As2S3 channel waveguide on top of an Er doped titanium diffused x-cut lithium niobate waveguide has been investigated by simultaneous analytical expressions, numerical simulations, and experimentation. Both simulation and experimental results have shown that this structure can enhance the optical gain, as predicted by the analytical expressions. An As2S3 channel waveguide has been fabricated on top of a conventional Er:Ti:LiNbO3 waveguide, where the higher refractive index As2S3 waveguide is used to pull the optical mode towards the substrate surface where the higher Er concentration yields an improved propagation gain. The relationship between the gain and As2S3 layer thickness has been evaluated and the optimal As2S3 thickness was found by simulation and experimentation. Side integration was applied to reduce the extra propagation loss caused by the titanium diffusion bump. The propagation gain (dB/cm) has been improved from 1.1 to 2 dB/cm. Another hybrid device which combines the As2S3 and LiNbO3 is to make an As2S3 racetrack ring resonator on top of an x-cut y-propagation Er:Ti:LiNbO3 waveguide which is the potential structure for integrated lossless all-path filter. The ring was side-coupled with the Ti:LiNbO3 waveguide and the optical gain was achieved when the 5mm long coupling region where has been diffused with Er in advance pumped by 144mW pump laser. The free spectral range (FSR) of the measured ring response for TM mode is 0.0587nm (7.33GHz) at 1550nm. The roundtrip loss are 4.4dB (2.60dB/cm) when pump on and 5.8dB (3.44dB/cm) when pump off. The optical gain in the Er diffused area is 0.72dB/cm.

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