Power amplifier linearization with adaptive predistorter for stable IMD characteristics

In this paper, an adaptive predistortion linearizer is proposed and fabricated for a power amplifier implementation. In order to compensate for intermodulation distortion (IMD) drift of the predistorted power amplifier, an adaptive algorithm based on the LMS (least mean square) criterion is proposed. Improvement of 12.67 dB in 2-fone test and adjacent channel power ratio (ACPR) reduction of 6 dB is achieved for the IS-95 CDMA cellular system by applying the adaptive predistorter to power amplifier with an average power of 16 W. From the experimental results, the ACPR characteristics is maintained within a constant value less than -45 dBc when the outside temperature changes from -10 /spl deg/C to 50 /spl deg/C.