A feedback predistortion technique for power amplifiers based on amplitude and phase signal processing

This paper presents a feedback predistortion technique for power amplifiers based on amplitude and phase signal processing to correct distortion in RF power amplifiers (PAs). By employing input and output signals of the power amplifier, the changes of the amplitude and phase caused by the nonlinear PA are compared in this technique. Furthermore, adjustable voltage controlled variable attenuator (VVA) and voltage controlled variable phase shifter (VVP) are used to achieve the purpose of predistortion compensation. The simulation results show that the third-order intermodulation distortion (IMD3) suppression of over 20dB may be achieved over bandwidth of 1 MHz at 2.14GHz. The results also show an adjacent channel leakage ratio (ACLR) improvement of about 8dB for realistic wideband code-division multiple access (WCDMA) signal. This method is a promising technique for rectifying the nonlinearity of PAs.