Effect of Analog Predistortion Linearizer in Quasi Saturation Region of RF Power Amplifier

摘要

Analog predistorter is a low-cost solution which can moderately compensate for the weak nonlinearity of radio frequency (RF) power amplifier (PA) for mobile communication systems. In this paper, we propose to use an analog predistorter to compensate medium-level nonlinearity of PA in quasi-saturation region. In order to model the complicated nonlinearity in quasi-saturation region, the Rapp model is employed to fit both the ideal clipping device and FET device represented by Curtice FET model. The linearizer we employed is series-diode configured type, which can optimize the linearization performance by controlling the bias voltage of the diode. From simulation results, the third-order inter-modulation distortion ratio (IMD3) can be reduced by -10 dB on average when a two-tone signal is input. It is also concluded that the predistorter can effectively decrease the out of band emission in Orthogonal Frequency Division Multiplexing (OFDM) signal.