Digital Predistortion for Wideband High Efficiency RF Power Amplifiers for High Throughput Satellites

In satellite communications, there is considerable increasing demand to support higher data throughput on necessarily pre-allocated bandwidth channels. In communication payloads, the DC-to-RF power conversion efficiency is crucial and most of the DC power is consumed by the RF Power Amplifier (PA). Thus, maximizing the PA efficiency while maintaining low distortion is key. Both power and bandwidth efficiency could be increased by employing digital pre-distortion (DPD). This paper focuses on state-of-the-art DPD techniques and possible developments to fit in satellite communications. The toleration of effects of temperature, supply voltage, and load mismatch variations, are investigated. This research suggests that there are benefits to be gained; employing spectrally efficient modulation techniques and transmitting a high fidelity signal to result in less expensive space and ground segment transmitters. A proof-of-concept by simulation is presented for ultra-wideband applications. A novel DPD system architecture is proposed where envelope tracking (ET) of the driver amplifier (DA) and load modulation of the PA are used to maximize the overall PAE while high PAPR signals can be used. To the best of the authors’ knowledge, this is the first time that DPD has been proposed for large fractional bandwidth high PAPR signals for satellite communications