Temperature compensated digital predistorter for 3G power amplifiers

This paper proposes a new digital baseband predistorter architecture for 3G RF power amplifiers. The proposed architecture compensates for temperature drifts using a simple temperature sensoring feedback path coupled with a temperature dependant predistortion function. The proposed predistorter is composed of a static look-up table in parallel with an adjustment module that implements the temperature compensation function. Measured AM/AM and AM/PM characteristics of 100-W peak envelop power LDMOS power amplifier were used to evaluate the performances of the proposed predistorter. The results show 15dB improvement in the intermodulation distortion level at the power amplifier output under a CDMA2000 SR3 excitation. This improvement was maintained for amplifier's case temperature variations between 25°C and 45°C.