An Outphasing Power Amplifier for a Software Defined Radio

An Outphasing Power Amplifier for a Software Defined Radio

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Modern telecommunication systems are increasingly built using compact and cost efficient integrated circuits, which include the family of low-cost low-power transceivers. There has been a colossal migration from high performance processes to CMOS in the interest of cost. While there is a sizable number of CMOS radio transceiver implementations, considerable improvement is needed in flexibility, scalability, programmability, and finally (and most importantly) efficiency. Most published designs lag behind in one or more of these performance indices---in particular efficiency. The importance of designing high performance transmitters at low cost has only recently surfaced. New efficient modulations demand high performance from transmitters, hence the emergence of a new movement to design better and cheaper transmitters. In this thesis, an integrated, high-performance CMOS engine, which takes extensive advantage of DSP, is proposed. A technique known as outphasing is used that achieves the goal of LInear amplification using Nonlinear Components (LINC). First discussed in a 1935 paper by H. Chireix, outphasing is the process of adding two constant amplitude sine waves with a proper phase difference to get a variable amplitude signal. This means two amplifiers with high power efficiency can be, at least in theory, used to generate any arbitrary modulation. Despite the solid mathematics behind the technique, a realistic implementation has is yet to be published at the time of this writing. It will be demonstrated that, in order for an outphasing scheme to function at high efficiency levels, a fair amount of compensation and calibration is required. A careful implementation of such techniques yields unprecedented power amplification efficiencies in a software-defined framework for wireless standards such as GSM, EDGE, and WCDMA.If Cpar is ignored, one can immediately see that, since the power dissipation of the devices is zero and the passive ... is turned ON again to shunt Cpar to ground , no charge will go to waste and the efficiency can theoretically be 100%. This cananbsp;...

Title:An Outphasing Power Amplifier for a Software Defined Radio
Author:Shervin Moloudi
Publisher:ProQuest - 2008


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