Design and Digital Linearization of a High Efficiency Variable Conduction Angle Doherty Amplifier

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  • Author: By Sami Bousnina
The need for highly efficient, linear microwave power amplifiers has grown rapidly, espewave power amplifiers has grown rapidly, especially as mobile and satellite communication systems have been developed and expanded. These systems employ multilevel digital modulation techniques to achieve higher-data-rate and multimedia services. This results in a band-limited multi-carrier signal, which is spectrally efficient but exhibits time-varying amplitude and phase characteristics. For acceptable linearity in handling such multicarrier signals with high peak-to-average envelope ratios, the amplifier output power must be backed off from its peak value. This has the disadvantages of reducing amplifier efficiency, increasing energy consumption, and reducing the operating time of portable power sources. Such a tradeoff between linearity and efficiency is difficult to achieve with conventional amplifiers. One of the promising techniques for improving efficiency under output power backoff is the load-line modulation technique used in the Doherty amplifier.