In recent year, wireless communications systems require transmission of higher and higher data rates to foster various multimedia services. The multiple-input multiple-output (MIMO) antennas system has been studied to increase wireless channel capacity and reliability. The mutual coupling of MIMO antennas affects the capacity of the wireless channel. Traditionally, the minimal mutual coupling distance between antenna elements needs to be at least one half wavelength. When MIMO antenna system is used in miniature mobile device, the problem of mutual coupling becomes even more serious. In the first part of this thesis we propose a WLAN/WiMAX antenna that can be operated in 2.4 GHz (2.4¡V2.48 GHz) WLAN band; 2.5 GHz (2.5¡V2.7 GHz) and 3.5 GHz (3.4¡V3.7 GHz) WiMAX band. We use the inverted U slot band notch and omega slot band notch to reduce the mutual coupling in MIMO antennas. Our design is able to reduce the mutual coupling to be less than ¡V20 dB in all interested bands. In the second part, we propose a planar WLAN/WiMAX antenna that can be operated in 2.4 GHz (2.4¡V2.48 GHz), 5.2/5.8GHz (5.15-5.35GHz/5.725-5.825GHz) WLAN band; 2.5 GHz (2.5¡V2.7 GHz), 3.5 GHz (3.4¡V3.7 GHz) and 5.5 GHz (5.25-5.85 GHz) WiMAX band and mutual coupling of MIMO antenna is less than ¡V20 dB in all interested bands.

Multiple-input multiple-output (MIMO) is a well-known technique for efficiently increasing bandwidth utilization. However, the implementation of the MIMO receiver with a reasonable hardware cost is a big challenge. Most MIMO receivers exploit minimum mean-square error (MMSE), zero-forcing (ZF) and maximum-likelihood (ML) to detect MIMO signals. Among the detectors, the ZF detector is simple detector with low computational complexity, but lower performance compared to ML decoder, which has huge computational complexity. If the K-Best sphere decoding algorithm (SDA) is adopted, the system complexity can be substantially reduced and the performance can approach that of the ML scheme when the value K is sufficiently large. In this paper, a hard-output MIMO detector is implemented using the K-Best SDA for 4¡Ñ4 64-quadrature amplitude modulation (QAM) MIMO detection. The implementation is realized by using a 0.18-£gm CMOS technology. The implementation chip core area is 3.35mm2 with 229K gates, and the decoding throughput is up to 3.12Mb/s with a 25MHz clock rate.

The new generation wireless broadband access technology-WiMAX¡]Worldwide Interoperability for Microwave Access¡^, possessing advanced features, such as higher transmission rates, longer transmission distances and wider coverage, is considered as one of the key technologies that can affect the future development of wireless telecommunications industry. Taiwan has ranked it a priority developing industry and has integrated the strengths of industries, government agencies, academia and research institutes to aggressively promote it in order to establish a more complete miniature of WiMAX industry chain. For the purposes of attracting information industry to enter this field, encouraging new applied services and development and achieving the goal of bringing services to push forward industry, the National Communication Commission¡]NCC¡^has issued 3 wireless broadband access business licenses in both north and south areas on July 2007. The bid-winners all adopts WiMAX technology to set up broadband mobile network, and provides services. Thus, at present, the wireless broadband access business is equal to WiMAX business. Therefore, the development of WiMAX industry plays a decisive role in Taiwan¡¦s economic development, its effecting level to the whole economic impact deserves analyzing and researching carefully. Based mainly on the Input-Output model, this study uses ex post facto comparison group and domestic concepts to combine the viewpoints of industrial analysis with the categories of 2004 Input-Output Table published by National Statistics, Executive Yuan, R.O.C., and then, adjusts Input-Output Table into 40 departments according to the policy of developing WiMAX that aggressively pushes forward the equipment and applied service fields. After that, defines related industries of network setup area and proceeds industry categorizing. Furthermore, this research does the analysis of Input-Output related effects and of multiplier effect so as to determine the role what it can play in the whole economic system. In the meanwhile, this study predicts the economic benefits of future development in setting up WiMAX and the operating period and the spurring effect of other related industries. The following are the research results¡G 1. In the next 3 years period and 5 years period of developing WiMAX network, the estimated total amount of investments will 21,549 million NT dollars and 37,291 million NT dollars each . It is predicted that there will be a whole output of domestic economic system of 34,489 million NT dollars and 59,685 million NT dollars; the created income effect will be 7,675 million NT dollars and 13,282 million NT dollars; the employment will be 7,588 jobs and 13,131 jobs each. 2. In the next 3 years period and 5 years period of operation, the estimated final demand variation amount will be 18,006 million NT dollars and 101,961 million NT dollars each by WiMAX services to customer. It is predicted that there will be a whole output of economic system of 27,063 million NT dollars and 153,249 million NT dollars; the created income effect will be 11,760 million NT dollars and 66,595 million NT dollars; the employment will be 4,766 jobs, 26,987 jobs. In sum, the promotion of WiMAX network construction will have positive influencing effect on the domestic economic growth and the development of every kind of industry.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 100 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 85-91).

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This thesis presents the design of new integrated charge pumps with high performance. An analysis method is determined to evaluate the voltage gain, the output resistance and the conversion efficiency parameters of integrated charge pumps. An optimization method is developed to improve the performance through capacitor sizing based on area constraints. Several charge pumps structures are optimized and compared including the losses due to devices parasitics. Results show that the Dickson charge pump (voltage doubler) is the best structure for integration. Therefore, techniques to improve per- formance and conversion efficiency of integrated voltage doubler are proposed. Switch bootstrapping technique prevents short-circuit losses, improves driving capability, and enhances the overall efficiency. The application of charge reuse technique reduces the dynamic power losses of integrated voltage doublers and double charge pumps. A pro- totype of the integrated voltage doublers was fabricated in a 0.18-μm CMOS process with the proposed techniques. Measured results have been presented, demonstrating the improvements in performance and conversion efficiency, with a good correlation between measured and predicted results.

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