Abstract A 10-bit 1MSample/sec successive approximation A/D converter is described in this thesis. First, by a comparator designed with high input impedance is used for the load of the modified wide-swing R-2R D/A converter. The modified wide-swing R-2R D/A converter possesses a high impedance load thus the op-amp is used in the D/A converter can be neglected. Therefore, the usable swing range and the convertible speed are improved and the power consumption is reduced. Secondary, the modified wide-swing R-2R D/A converter that contains modified switch-circuit and matched-component is used to obtain the good voltage division thereby improving the accuracy. Finally, the modified timing skew-insensitive double-sampling S/H circuit is used to sample a high precision signal to the comparator. This modified timing skew-insensitive double-sampling S/H circuit consists of high-gain high-swing op-amp, CMOS dummy switches, and timing skew-insensitive technique for upgrading the precision and swing range. By using these improved circuits the overall speed, accuracy and swing range are improved. The proposed successive approximation A/D converter is designed by TSMC 1P4M 0.35£gm CMOS process, and it operates at 3.3V power supply voltage with 0.8 to 2.9V reference voltage. The simulation results show that DNL is 0.5LSB, INL is 1LSB, and the power consumption is 8mW.

For A/D converters in ultra-wideband (UWB) communication systems, the flash A/D type is commonly used because of its fast speed and simple architecture. However, the number of comparators in a flash A/D converter exponentially increases with an increase in resolution; therefore, an interpolating technique is proposed in this thesis to mitigate the exponential increase of comparators in a flash converter. The proposed structure is designed to improve the system bandwidth degradation by replacing the buffers and resistors of a typical interpolating technique with a pair of transistors. This replacement mitigates the bandwidth degradation problem, which is the main drawback of a typical interpolating A/D converter. With the proposed 4-bit interpolating structure, 3.75 of effective number of bits (ENOB) and 31.52dB of spurious-free dynamic range (SFDR) are achieved at Nyquist frequency of 264MHz with 6.93mW of power consumption. In addition, a 4-bit D/A converter is also designed for the transmitter part of the UWB communication system. The proposed D/A converter is based on the charge division reference generator topology due to its full swing output range, which is attractive for low-voltage operation. To avoid the degradation of system bandwidth, resistors are replaced with capacitors in the charge division topology. With the proposed D/A converter, 0.26 LSB of DNL and 0.06 LSB of INL is obtained for the minimum input data stream width of 1.88ns. A 130 µm ×286 µm chip area is required for the proposed D/A converter with 19.04mW of power consumption. The proposed A/D and D/A converter are realized in a TSMC 0.18 µm CMOS process with a 1.8 supply voltage for the 528MHz system frequency.

<h1>Abstract</h1><p>This thesis has been done in Barcelona, Spain, in cooperation with the University of Gävle (HiG) and the Universitat Politècnica de Catalunya (UPC). At UPC there is a project carried out where the goal is to analyze the characteristics and performance of the wind turbine IT-100, with an intention to optimize it. This is carried out by assignment of Engineers Without Borders and Practical Action. The purpose of the thesis has been to present what power, value of tension and current the turbine will produce in different wind velocities.</p><p> </p><p>The IT-100 is built to generate electricity to the population in the countryside in, among other countries, Peru. The energy the turbine captures from the wind will be used to charge vehicle batteries that are used in the households as a source of electricity. This is an effective, cheap and environmental-friendly way of supplying households with electricity.</p><p> </p><p>The idea of using the energy in the wind has been known for thousands of years. It started with simple windmills for grinding grain and later more complicated machines like wind turbines were created. Wind power is one of the worlds cleanest sources of energy with as good as no emissions at all while in running.</p><p> </p><p>The result of the work with this thesis work is an Excel file where the, by the purpose requested, parameters are presented in relation to different wind velocities. With some conditions set from the start, some known values of reference and the rotor blades rotational speed as a key variable, these parameters were possible to calculate.</p><p> </p><p>During the work, the project came upon some difficulties such as; not enough information about the wind turbine, too little previous knowledge among the students and trouble with the Spanish language. However, on the whole the project has been successful and a good learning experience.</p>

Abstract This thesis has been done in Barcelona, Spain, in cooperation with the University of Gävle (HiG) and the Universitat Politècnica de Catalunya (UPC). At UPC there is a project carried out where the goal is to analyze the characteristics and performance of the wind turbine IT-100, with an intention to optimize it. This is carried out by assignment of Engineers Without Borders and Practical Action. The purpose of the thesis has been to present what power, value of tension and current the turbine will produce in different wind velocities.   The IT-100 is built to generate electricity to the population in the countryside in, among other countries, Peru. The energy the turbine captures from the wind will be used to charge vehicle batteries that are used in the households as a source of electricity. This is an effective, cheap and environmental-friendly way of supplying households with electricity.   The idea of using the energy in the wind has been known for thousands of years. It started with simple windmills for grinding grain and later more complicated machines like wind turbines were created. Wind power is one of the worlds cleanest sources of energy with as good as no emissions at all while in running.   The result of the work with this thesis work is an Excel file where the, by the purpose requested, parameters are presented in relation to different wind velocities. With some conditions set from the start, some known values of reference and the rotor blades rotational speed as a key variable, these parameters were possible to calculate.   During the work, the project came upon some difficulties such as; not enough information about the wind turbine, too little previous knowledge among the students and trouble with the Spanish language. However, on the whole the project has been successful and a good learning experience.

Electroabsorption modulators (EAM) have attract a lot of interests in high-speed optical communication due to low chirp, high-efficiency operation and the capability to be integrated with other semiconductor devices. Enhancing the operation by overcoming the trade-off between RC-limitation and high-speed performance, traveling-wave types of EAMs (TWEAM) have been documented to be a good candidate. In this thesis, a novel type of TWEAMs, namely undercut-etching-the-active-region type (UEAR), have been characterized and analyzed. There are two topics in this thesis, namely (1) one is to compare the performance of the UEAR and conventional ridge-waveguide (RW) types of TWEAM. The regime of D.C. to 40GHz small-signal modulation and 10 Gbits/sec large-signal data transmission are used to characterize and compare the performance of TWEAMs. In comparison with conventional ridge-waveguide (RW) TWEAM, 3dB lower optical-insertion-loss, at least 6dB higher in RF-link (D.C. to 40GHz) and faster electro-optical response (3dB bandwidth of 25GHz at 50£[-termination for UEAW and 15GHz for RW) are obtained in UEAW-TWEAM. Error-free 10Gbits/sec operation with high sensitivity of ¡V36.2 dBm and low swing voltage of 0.6V have been achieved in UEAW-TWEAM, a 3.2dB enhancement over RW-TWEAM, indicating the trade-off in designing electroabsorption modulators can be greatly released by novel type structure (UEAW). (2) The other topic is the application of TWEAM to all-optical wavelength converters. The generating photocurrent by optical absorption is the effect accompanying with the electrical-to-optical modulation in the EAM. Using the properties of cross-absorption and generating photocurrent, high-speed all-optical modulation can be potentially implemented in the application of EAMs. Long -waveguide high-speed TWEAMs can thus have high-extinction ratio performance in all-optical conversion. The conversion efficiency of -26dB and high extinction ration of >20dB are obtained in this experiment, showing the potential in the application of all-optical conversion.

In this paper, we present a low-power low-cost 6-bits, ADC using selective reference voltage technique. Using selective reference voltage technique, the different bit uses different comparator can be achieved. Meanwhile, the outputs from comparators are a binary code which can be used for generating logic condition thereby controlling the switches. Because the conventional n bits flash ADC requires 2n - 1 comparators and its power, area and input capacitance are all proportional to 2n - 1. Whereas, the proposed n bits ADC needs only n comparators which can save more power and area, and its input capacitance are proportional to n only, and keep high speed. Our proposed ADC is design by TSMC 1P6M 0.18£gm process with 6-bits resolution, 1.8V power supply. The signal input range 0.5V~1.1V, sampling rate 256MS/s, DNL +0.46LSB~ -0.49LSB, INL +0.85LSB~ -0.05LSB. In addition, the FOM of the ADC is only 0.26 pJ/Conv and the power consumption is only 4.2mW.It is good for a low-power and low cost customer electronic application.

Semiconductor Electroabosortion Modualtor (EAM) has become an important element in optical fiber communications because of its capability to integrate with other semiconductor devices, high-speed and low driving voltage. However, high optical insertion loss and low tolerance in optical power coupling are main general problems to be solved in order to get high electro-optical (EO) efficiency. Monolithically integrating EAM with optical spot-size converter (SSC) can lead to high-efficiency single-mode fiber coupling, but the price is on the complex fabrication methods. In this paper, based on previous work, the selective undercut etching active region (UEAR) and the whole wet-etching techniques are employed to fabricate the integration of laterally tapered SSC and EAM. Also, by applying the ion-implantation in SSC region, the reliable transfer efficiency and also high-speed performance are obtained based on the high resistance and low parasitic capacitance in SSC. The active region containing 10 strain compensated multiple-quantum-wells (MQWs) sandwiched by n-InP (bottom) and p-InP (top) for the electroabsorption region of EAM and also the top region of lateral tapered SSC. The converted waveguide in SSC consists of alternating InGaAsP and InP layers. An HBr-base etching solution is first used to define the top p-cladding with the widths of from 6um to 8um. An H2O2-base solution is then utilized to selectively undercut-etch the MQWs from InP material. The active waveguide p-cladding in EAM is set as 8um. After defining EAM and SSC, the converted waveguide is fabricated by aligning the top SSC and then wet-etched. By using an e-beam evaporator, Ti/Pt/Au and Ni/AuGe/Ni/Au are deposited as p- and n-type metallization, respectively. PMGI is spun serving as the passivation, planarization and bridging. The microwave coplanar waveguide (CPW) line is finally defined by depositing Ti/Au for microwave load- and feed- lines and connecting EAM. The length of SSC is 350um. The Spot-Size Converter monolithically integrated with Electroabsortion Modulator using whole wet-etching technique is demonstrated. ¡V12.5dB of fiber-to-fiber insertion loss and 10dB (TE) 10dB(TM) extinction ration in 1V(1570nm excitation) is obtained in this device. Using Fabry-Perot method, the average optical transfer loss in SSC is extracted to be 2dB, quite consistent with simulation results. By applying ion-implantation on SSC, the broadband EO performance 45GHz of ¡V3dB bandwidth is achieved for 100um long device due to the low capacitance and the high resistivity in SSC.

We present the fabrication of InGaAsP/InP buried heterostructure spot-size converter lasers. In the lateral conversion, we use photolithography to make tapered ridge waveguides. In the vertical conversion, we use a pair of step-index passive waveguides, namely guard waveguides (GWs), in the two sides of the step-index active waveguide region to increase optical-field profile. In order to decrease leakage current, we use a p-n-p current blocking structure by MOCVD regrowth. From numerical simulations, the far-field divergence is 21x21. The step-index GW structure shows an internal efficiency of 63%. However, the BH lasers did not lase from our fabrication processes. From the I-V characteristics, a large leakage current has bypassed through the blocking structure. The reason may relate to the high background doping concentration of our MOCVD growth.

Abstract Optical spot-size converter (SSC) is an essential element in the opto-electronic integrated circuit because of its direct coupling to single-mode optical fiber, low-cost from the misalignment issue in package. By the tapered waveguide structure, SSC offers a capability to transfer an elliptical optical mode of optical waveguide to single-mode fiber matched mode, allowing the independence of device design from the coupling issue. However, the conversion efficiency of SSC is strongly reliant on tapered waveguide structure, material index, and also excitation wavelengths, restricting design and fabrication of SSC. In order to enhance the reliability on SSC fabrication, a voltage-controllable SSC integrated with electroabsorption modulator (EAM) is designed and fabricated. The tapered waveguide processing is based on the selective undercut wet-etching on InGaAsP-material system. The active waveguide width of EAM is 3.5£gm, where the tapered waveguide widths is ranged from 1.7£gm to 3.5£gm. The transferred optical waveguide (passive waveguide) is 8£gm wide. By adjusting the voltage of tapered waveguide, coupling efficiency is enhanced by 2dB from 1560nm to 1570nm. A reliable SSC-integrated EAM with -12dB of insertion loss, extinction ratio of 22dB is demonstrated. By extracting the index change from Fabry-Perot optical mode of waveguide, index variation from reverse bias is in the order of 10-3, consistent with the calculation based on Kramer-Kronig model.

To enhance the progress of control of switching converters, IP blocks should be identified and be made available. These power technologies can be readily implemented and the pace of progress be enhanced. This article discusses the implementation of bi-lateral switches. From the example presented, it will be clear that control of the switches is a combination of fixed commutation techniques and variable intelligent control.