Predistortion circuit for a power amplifier
 A predistortion circuit for a radio frequency power amplifier which has gain and phase shift characteristics that are non-linear as a function of power level of an RF input signal. The circuit includes a dual gate FET, with a drain coupled to the power amplifier. A modulated RF input signal is applied to an inductive matching network which is coupled to the signal gate of the FET. A modulating envelope detected version of the input signal is applied to a video amplifier which is coupled to the FET control gate. The signal applied to the control gate varies the gain of the FET as a function of input signal to compensate for the non-linear gain characteristic of the power amplifier and in conjunction with the matching network causes a phase change of the signal through the predistortion circuit to compensate for the non-linear phase characteristic of the power amplifier. 
RCA Corporation
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H03F H03F
inventional inventional
Mahesh Ho-Chung Franco N.
Kumar Huang Sechi