Digital predistortion linearizer for compensating frequency-dependent IM distortion

This paper proposes a new digital predistortion linearizer based on power series representation that strongly suppresses intermodulation distortion (IMD). The proposed predistortion linearizer is equipped with distortion generation paths that consist of odd-order distortion generators, vector regulators and frequency characteristics compensators. The proposed linearizer compensates the frequency characteristics of IMD, which limit the performance of current predistortion linearizers. In an experiment, the 3rd- and 5th-order IMD components are successfully suppressed by the proposed predistortion linearizer when a three-tone signal is input. The 3rd- and 5th-order IMD components are less than 4 0 dB at the output back-off of 3 dB from the 1 dB gain compression point as measured with a single-tone.