Efficient Linear Amplification Using Digitally Predistorted Overdriven Power Amplifiers

This paper investigates the effects of crest factor reduction and digital predistortion on the performances of communication and broadcasting systems. The overdrive of digitally predistorted power amplifiers is proposed for power efficient linear amplification of amplitude modulated signals having high peak to average power ratio. This is achieved by adding, at the input of the digital predistortion system, a clipping function to allow for an overdrive of the linearized power amplifier while meeting spectrum emission mask linearity requirements. The proposed technique is experimentally validated using a GaN Doherty power amplifier driven by long-term evolution (LTE) signals. Measurement results show that the overdriven power amplifier can deliver up to 2.5 dB extra output power, up to 80% enhancement in the power utilization factor, and up to 20% relative increase in the power efficiency while being compliant with the linearity requirements of the LTE standard.