Linearization of Power Amplifier with Method of the Modified Feed Forward
Subject Areas : electrical and computer engineeringM. R. Motavalli Kasmaie 1 , M. R. Motavalli Kasmaie 2
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Keywords: Feed forward amplifier power amplifier 3IMD signals Voltrra series,
Abstract :
This paper offers a modified circuit for improving linearization of power amplifier with based on the model of the Feed Forward circuit amplifier. With the help of mathematical model for the single power amplifier, the circuit is simulated und a demonstrator is built and measured. it is used a complex Taylor series for modeling the power amplifier by the approximation of the amplitude transfer function and the level-dependence of the transmission-phase of the power amplifier and can be understood as a simplified form of Volterra series. In our proof of concept experiment, we verified the concept but also found that the adjustment of the circuit is critically dependent on the drive conditions and linearization is achieved only for a narrow range of drive power. The simulation of the total circuit is largely determined by the models for the transmission characteristics of the two power amplifiers. The new circuit in compare with the conventional Feed Forward amplifier, in addition a significant increase in efficiency to minimize the power of the distortion signal 3IMD for large driving amplitude (large signals).
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