Image Number 5 for United States Patent #5838195.
Second harmonic distortion of a traveling wave tube amplifier with a bandwidth exceeding one octave is efficiently minimized by generating a low-power second harmonic signal, modifying it by an adaptive filter, and adding the modified second harmonic signal to the fundamental frequency input signal to the TWT. The adaptive filter is controlled by a feedback loop from the output of the TWT and is arranged to minimize the correlation between the generated second harmonic signal and the second harmonic content of the TWT output. Intermodulation distortion is eliminated in a similar manner.
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