A Linearized Cascode CMOS Power Amplifier

In this paper, an RF predistorter linearizer compatible with a CMOS process is proposed. The predistorter uses a diode connected MOSFET as a nonlinearity generation circuit. A negative or positive AM-PM characteristic is obtained from the predistorter by inserting a capacitor or an inductor in parallel with the predistorter. A 5.8 GHz cascode CMOS power amplifier was designed using a 0.18-mum 1P6M mixed-mode CMOS process and a predistorter was customized for the cascode power amplifier and integrated with it. The gain and phase distortion of the power amplifier were compensated and the simulation result of the cascode power amplifier shows a 29.3-dB improvement in the third order inter-modulation distortion when the predistorter is turned on.