Holistic Design of Power Amplifiers for Future Wireless Systems

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Power amplifiers are one of the main fundamental building blocks of all modern wireless communications systems. They are used in all base stations and all the mobile units which are currently available. To maintain the required levels of system performance current commercially available amplifiers are designed to operate with extremely poor levels of efficiency which means they consume far more energy than is strictly necessary. For example current base stations in the UK operate at an efficiency level of approximately 12% this results in over 609,000 of CO2 emissions into the atmosphere on an annual basis. If these base stations were to be 50% efficient CO2 emissions could be cut by over 450,000 tons per year. The design of highly efficient and highly linear power amplifiers is an extremely complex process. At present the design of highly linear amplifiers is carried out using a trial-and-error based approach where designs are drawn up, then a prototype is produced and design issues are identified. The whole process is repeated until an optimum solution is reached. This has lead manufacturers to take a very risk adverse approach to amplifier design which has resulted in very inefficient systems. There is an increasing need to develop wireless communications systems with increased digital data throughput. For example, in recent years we have seen the roll out of 3rd generation 3G mobile communication systems and the increasing use of wireless LAN systems. It is highly likely that the future so-called 4th generation systems will contain modulation schemes which also use wireless LAN technology. With the introduction of 3G systems it became clear that the existing design methodologies for the development and optimisation of amplifiers are labour intensive and time consuming. The present approach has become a key hindrance in the evaluation, development, and testing of modern communication systems. This proposal seeks to overcome these fundamental design issues through the establishment of a scientifically robust fully interlinked design methodology for nonlinear circuits. By combining the world-class power amplifier design expertise in Bristol and waveform measurement/engineering expertise /introduced and pioneered in Cardiff/ a scientifically robust nonlinear design methodology will be established in which the measured waveforms and waveform engineering will facilitate new methods of amplifier design and linearisation. The aim being a one pass design process for future communications systems which will result in the exploitation of this technology within a commercial setting.