Power Amplifier Linearization Using Six-port Receiver for DVB-S2 Satellite Communications

A digital look-up table adaptive predistortion technique using a six-port receiver for power amplifier linearization is presented. The system is designed in Ka-band for a DVB-S2 satellite link. We use a six port receiver at the linearization loop in place of classic heterodyne receivers. The six-port receiver is implemented by the use of passive microwave circuits and detector diodes. This approach highly reduces cost and complexity of the linearization system. The fabrication results of a five-port receiver operating in 23–29 GHz is presented in this paper. The simulation results confirm suitability of using this architecture in the power amplifier linearization loop. The third order intermodulation products and the fifth order intermodulation products reduce about 43 dB and 25 dB respectively, after linearization ofthe power amplifier. The resulting spectrum of the output signal shows significant reduction of the intra-system interference to the adjacent networks which is mainly due to the nonlinearity effects of the power amplifier.