Efficient amplification of signals with high PAPR using a novel multilevel LINC transmitter architecture

This paper presents a novel energy-efficient multi-standard multilevel LINC transmitter architecture. The proposed system is able to provide a large number of reconfigurable multiple levels by arbitrarily controlling the output power of the two efficient power amplifiers. The novelty of the architecture relies in the efficient generation of the arbitrary multilevels. In fact, the system uses only one fixed supply voltage. An algorithm is developed to optimise the different symmetrical levels depending on the actual signal statistics in order to boost average system efficiency. A multilevel LINC transmitter system demonstrator was build to validate the proposed concept. Besides The system employs two identical hybrid power amplifiers designed using GaN HEMTs for a centre frequency of 2.28 GHz and output power of 40 dBm, the system employs only off-the-shelf components or measurement equipment. Measurement results on the demonstrator show that compared with a conventional LINC transmitter, average power efficiency of the proposed system can be improved from 28 % to 41 % for a WCDMA signal with a measured adjacent-channel-power ratio (ACPR) below -45 dBc. For a 10 MHz LTE signal efficiency is improved by nearly 24 percentage-points compared with a regular LINC system.